In the last decade,a new neurological disease concept known as anti-myelin oligodendrocyte glycoprotein antibody(MOG-IgG)-associated disease(MOGAD)has emerged and is currently one of the most focused research areas in...In the last decade,a new neurological disease concept known as anti-myelin oligodendrocyte glycoprotein antibody(MOG-IgG)-associated disease(MOGAD)has emerged and is currently one of the most focused research areas in the field of neuroimmunology.MOG is a membrane protein mainly expressed on the surface of oligodendrocytes(Zhou et al.,2006).The exact pathogenic role of MOG-IgG in patients with MOGAD remains unclear;however,MOG-IgG has been suggested to cause tissue alterations and damage MOG-expressing cells(Zhou et al.,2006).The pathogenicity of MOG-IgG is further supported by the observation that only a few patients with acquired central nervous system(CNS)demyelinating syndromes exhibit both anti-aquaporin-4 antibody(AQP4-IgG)and MOG-IgG simultaneously,particularly with clear positivity levels of these antibodies as indicated by a cell-based assay result with a titer≥1:100(Sechi et al.,2021;Banwell et al.,2023).展开更多
BACKGROUND A case of neuromyelitis optica spectrum disorder(NMOSD)with positive cerebrospinal fluid(CSF)anti-aquaporin-4 antibody(AQP4-IgG)and anti-glial fibrillary acidic protein IgG(GFAP-IgG)at the time of relapse w...BACKGROUND A case of neuromyelitis optica spectrum disorder(NMOSD)with positive cerebrospinal fluid(CSF)anti-aquaporin-4 antibody(AQP4-IgG)and anti-glial fibrillary acidic protein IgG(GFAP-IgG)at the time of relapse was reported.The exact roles of GFAP-IgG in NMOSD are not fully understood and are the subject of ongoing research.This study revealed the possible connection between GFAPIgG and the occurrence or development of diseases.CASE SUMMARY A 19-year-old woman was admitted to the hospital due to a constellation of symptoms,including dizziness,nausea,and vomiting that commenced 1 year prior,reoccurred 2 mo ago,and were accompanied by visual blurring that also began 2 mo ago.Additionally,she presented with slurred speech and ptosis,both of which emerged 1 mo ago.Notably,her symptoms deteriorated 10 d prior to admission,leading to the onset of arm and leg weakness.During hospitalization,magnetic resonance imaging showed high T2-fluid attenuated inversion recovery signals,and slightly high and equal diffusion-weighted imaging signals.The serum antibody of AQP4-IgG tested positive at a dilution of 1:100.CSF antibody testing showed positive results for GFAP-IgG at a dilution of 1:10 and AQP4-IgG at a dilution of 1:32.Based on these findings,the patient was diagnosed with NMOSD.She received intravenous methylprednisolone at a daily dose of 500 mg for 5 d,followed by a tapering-off period.Afterward,the rate of reduction was gradually slowed down and the timely use of immunosuppressants was implemented.CONCLUSION The CFS was slightly GFAP-IgG-positive during the relapse period,which can aid in the diagnosis and treatment of the disease.展开更多
BACKGROUND: Aquaporin-4 (AQP-4), which is able to rapidly transport water within the brain, is highly expressed in brain tissue. It also plays an important role in the formation of cerebral edema following brain injur...BACKGROUND: Aquaporin-4 (AQP-4), which is able to rapidly transport water within the brain, is highly expressed in brain tissue. It also plays an important role in the formation of cerebral edema following brain injury. However, the role of AQP-4 in the formation of cerebral edema following severe burns remains unknown. OBJECTIVE: To study changes in AQP-4 protein and mRNA expression during formation of cerebral edema following severe burns, and to explore the correlation between AQP-4 protein and mRNA expression with plasma levels of arginine vasopressin (AVP). DESIGN, TIME AND SETTING: A randomized, controlled, animal experiment was performed at the Research Center of Neuroscience, Chongqing Medical University from 2007 to 2008. MATERIALS: Biotin-labeled goat anti-rabbit antibody was provided by Beijing Zhongshan Biotechnology, China; in situ hybridization kit was provided by Wuhan Boster Biotechnology, China; rabbit anti-AQP-4 polyclonal antibody and horseradish peroxidase-labeled goat anti-rabbit IgG were provided by Chemicon, USA; AVP radioimmunoassay kit was provided by the Research Department of Neurobiology, the Second Military Medical University of Shanghai, China. METHODS: A total of 180 adult, healthy, Wistar rats were randomly assigned to control and burn groups with 30 rats in each group. The burn group was observed at five different time points: 2, 6, 12, 24, and 48 hours after burn. Hair on the mouse back was removed to expose skin on the back. After 1 day, skin with the hair removed was dipped into 100 °C water for 15 seconds to induce grade III burn injury that measures 30% of total burn surface area. MAIN OUTCOME MEASURES: Brain water content was measured using the dry-wet weight method. AQP-4 protein and mRNA expressions were detected using immunohistochemistry, in situ hybridization, Western blot, and reverse transcription-polymerase chain reaction; dynamic changes in plasma AVP were detected using radioimmunoassay. RESULTS: Brain water content gradually increased following severe burn injury. AQP-4 protein and mRNA expressions were upregulated in the supraoptic nucleus, suprachiasmatic nucleus, paraventricular nucleus, hippocampus, choroid plexus, and cerebral cortex. Plasma AVP levels increased following burn injury. AQP-4 protein and mRNA expressions positively correlated with brain water content and AVP levels during formation of cerebral edema (r = 0.870, 0.848, P < 0.01). CONCLUSION: AQP-4 participated in the formation of cerebral edema following burn injury. Plasma AVP upregulated AQP-4 expression in brain tissue, thereby promoting formation of cerebral edema.展开更多
Objective: To characterize the expression of aquaporin-4 (AQP4), one of the aquaporins (AQPs), in human brain specimens from patients with traumatic brain injury or brain tumors. Methods: Nineteen human brain specimen...Objective: To characterize the expression of aquaporin-4 (AQP4), one of the aquaporins (AQPs), in human brain specimens from patients with traumatic brain injury or brain tumors. Methods: Nineteen human brain specimens were obtained from the patients with traumatic brain injury, brain tumors, benign meningioma or early stage hemorrhagic stroke. MRI or CT imaging was used to assess brain edema. Hematoxylin and eosin staining were used to evaluate cell damage. Immunohistochemistry was used to detect the AQP4 expression. Results: AQP4 expression was increased from 15h to at least 8 d after injury. AQP4immunoreactivity was strong around astrocytomas, ganglioglioma and metastatic adenocarcinoma. However, AQP4 immunoreactivity was only found in the centers of astrocytomas and ganglioglioma, but not in metastatic adenocarcinoma derived from lung.Conclusion: AQP4 expression increases in human brains after traumatic brain injury, within brain-derived tumors, and around brain tumors.展开更多
BACKGROUND:Aquaporin-4 (AQP-4) over-expression following cerebral ischemia results in cerebral edema. Picroside Ⅱ has been shown to exhibit a neuroprotective effect on neuronal apoptosis. However,few reports have add...BACKGROUND:Aquaporin-4 (AQP-4) over-expression following cerebral ischemia results in cerebral edema. Picroside Ⅱ has been shown to exhibit a neuroprotective effect on neuronal apoptosis. However,few reports have addressed the neuroprotective mechanisms and therapeutic times following cerebral ischemic reperfusion injury. OBJECTIVE:To explore the neuroprotective effects and ideal treatment window for picroside II treatment of middle cerebral artery occlusion and reperfusion injury in rats. DESIGN,TIME AND SETTING:A randomized,controlled,animal experiment was performed at Institute of Cerebrovascular Diseases,Qingdao University Medical College from September 2008 to May 2009. MATERIALS:Picroside Ⅱ was purchased from Tianjin Kuiqing Medical Technology,China. METHODS:A total of 165 adult,healthy,male,Wistar rats were randomly assigned to sham-surgery (n = 15),model (n = 75),and treatment groups (n = 75). Rats in the model and treatment groups underwent middle cerebral artery occlusion and reperfusion through the use of an intraluminal monofilament suture on the left external-internal carotid artery. The treatment group was injected with 1.0% picroside Ⅱ (10 mg/kg) into the tail vein,and the model and sham-surgery groups were injected with 0.1 mol/L phosphate buffered saline (250 μL). MAIN OUTCOME MEASURES:Neurological functional scores were evaluated using the Longa's method; cerebral infarction volume was detected through the use of tetrazolium chloride staining; cellular apoptosis was determined through the use of the in situ end-labeling method; aquaporin-4 expression was measured using fluorescence labeling analysis and reverse transcription polymerase chain reaction technique. RESULTS:At 0.5 hour following cerebral ischemic injury,neurological functional scores were low,and a small infarction focus was detected in the ischemic cortex of the model group. Along with prolonged ischemia and an increased number of apoptosis-positive cells,AQP-4 mRNA and protein expression was increased. At 1-2 hours after ischemia,neurological scores and infarction sizes were significantly increased in the model group. Apoptotic-positive cells were widespread in the ipsilateral cortex and striatum. In addition,AQP-4 mRNA and protein expression levels were increased. Picroside Ⅱ treatment significantly decreased neurological scores and infarction volume,and reduced AQP-4 mRNA and protein expression levels compared with the model group (P < 0.05 or P < 0.01). At 1 hour after ischemia,the therapeutic effect of picroside Ⅱ was notable (P < 0.01). CONCLUSION:Picroside Ⅱ played a protective role in cerebral ischemic reperfusion injury by inhibiting apoptosis and regulating AQP-4 expression. The best therapeutic time window was 1 hour after cerebral ischemic reperfusion.展开更多
Edema formation is a major problem following traumatic spinal cord injury(SCI) that acts to exacerbate secondary damage.Severity of edema correlates with reduced neurological outcome in human patients.To date, there a...Edema formation is a major problem following traumatic spinal cord injury(SCI) that acts to exacerbate secondary damage.Severity of edema correlates with reduced neurological outcome in human patients.To date, there are no effective treatments to directly resolve edema within the spinal cord.The aquaporin-4(AQP4) water channel is found on membranes of astrocytic endfeet in direct contact with blood vessels, the glia limitans in contact with the cerebrospinal fluid and ependyma around the central canal.Being so locally expressed at the interface between fluid and tissue allow AQP4 channels to play an important role in the bidirectional regulation of water homeostasis under normal conditions and following trauma.With the need to better understand the pathophysiology underlying the devastating cellular events in SCI, animal models have become an integral part of exploration.Inevitably, several injury models have been developed(contusion, compression, transection) resulting in difficult interpretation between studies with conflicting results.This is true in the case of understanding the role of AQP4 in the progression and resolution of edema following SCI, whose role is still not completely understood and is highly dependent on the type of edema present(vasogenic vs cytotoxic).Here, we discuss regulation of AQP4 in varying injury models and the effects of potential therapeutic interventions on expression, edema formation and functional recovery.Better understanding of the precise role of AQP4 following a wide range of injuries will help to understand optimal treatment timing following human SCI for prime therapeutic benefit and enhanced neurological outcome.展开更多
BACKGROUND:Previous studies have demonstrated that aquaporin-4 (AQP4) plays a key role in the formation and resolution of brain edema.However,the molecular mechanisms and role of AQP4 in hypoxia-ischemia-induced brain...BACKGROUND:Previous studies have demonstrated that aquaporin-4 (AQP4) plays a key role in the formation and resolution of brain edema.However,the molecular mechanisms and role of AQP4 in hypoxia-ischemia-induced brain edema remain poorly understood.OBJECTIVE:To establish a newborn animal model of astrocytic oxygen-glucose deprivation and reintroduction,to observe the correlation between AQP4 and cellular volume,and to investigate the role of AQP4 in the development of brain edema following oxygen deprivation and reintroduction.DESIGN,TIME AND SETTING:A comparative experiment was performed at the Experimental Center of West China Second University Hospital between October 2007 and April 2009.MATERIALS:Astrocytes were derived from the neocortex of Sprague Dawley rats aged 3 days.METHODS:Astrocytes were incubated in glucose/serum-free Dulbecco's modified Eagle's medium,followed by 1% oxygen for 6 hours.Finally,oxygen-glucose deprivation and reintroduction models were successfully established.MAIN OUTCOME MEASURES:Real-time polymerase chain reaction and Western blot analysis were used to measure expression of AQP4 mRNA and protein in cultured rat astrocytes following oxygen-glucose deprivation and reintroduction.Astrocytic cellular volume,as determined by [3H]-3-O-methyl-D-glucose,was used to represent the extent of astrocytic swelling.RESULTS:During oxygen-glucose deprivation,AQP4 mRNA and protein expression gradually decreased in astrocytes,whereas cellular volume increased in a time-dependent manner (P < 0.01).Following oxygen-glucose reintroduction,AQP4 mRNA and protein expression was upregulated,peaked at day 7,and then gradually decreased,but still higher than normal levels (P < 0.05).However,cellular volume gradually decreased (P < 0.01),and then reached normal levels at day 7.CONCLUSION:AQP4 expression highly correlated with cellular volume changes,suggesting that AQP4 played an important role in modulating brain water transport in an astrocytic oxygen-glucose deprivation and reintroduction model.展开更多
BACKGROUND: Aquaporin-4 (AQP-4) is closely related to the formation of brain edema. Neuronal apoptosis plays an important part in the conversion of swelled neuron following traumatic brain injury. At present, the stud...BACKGROUND: Aquaporin-4 (AQP-4) is closely related to the formation of brain edema. Neuronal apoptosis plays an important part in the conversion of swelled neuron following traumatic brain injury. At present, the studies on the protective effect of ketamine on brain have involved in its effect on aquaporin-4 expression and neuronal apoptosis in the brain tissues following brain injury in rats. OBJECTIVE: To observe the effect of ketamine on AQP-4 expression and neuronal apoptosis in the brain tissue following rat brain injury, and analyze the time-dependence of ketamine in the treatment of brain injury. DESIGN: Randomized grouping design, controlled animal trial.SETTING: Department of Anesthesiology, the Medical School Hospital of Qingdao University.MATERIALS: Totally 150 rats of clean grade, aged 3 months, were involved and randomized into control group and ketamine-treated group, with 75 rats in each. Each group was divided into 5 subgroups separately at 6,12, 24, 48 and 72 hours after injury, with 15 rats at each time point. Main instruments and reagents: homemade beat machine, ketamine hydrochloride (Hengrui Pharmaceutical Factory, Jiangsu), rabbit anti-rat AQP-4 polyclonal antibody, SABC immunohistochemical reagent kit and TUNEL reagent kit (Boster Co.,Ltd., Wuhan). METHODS: This trial was carried out in the Institute of Cerebrovascular Disease, Medical College of Qingdao University during March 2005 to February 2006. A weight-dropping rat model of brain injury was created with Feeney method. The rats in the ketamine-treated group were intraperitoneally administered with 50 g/L ketamine (120 mg/kg) one hour after injury, but ketamine was replaced by normal saline in the control group. In each subgroup, the water content of cerebral hemisphere was measured in 5 rats chosen randomly. The left 10 rats in each subgroup were transcardiacally perfused with ketamine, then the brain tissue was made into paraffin sections and stained by haematoxylin and eosin. Neuronal morphology was observed. AQP-4 expression and neuronal apoptosis were measured with immunohistochemical method and TUNEL method respectively. MAIN OUTCOME MEASURES: Water content in brain tissue, neuronal morphology, the number of AQP-4 positive neurons and TUNEL positive neurons in rats of two groups at each time point after injury.RESULTS: Totally 150 rats entered the stage of result analysis. ① Water content of brain tissue: The water content of brain tissue at each time point after injury in the ketamine-treated group was lower than that in the control group. There were very significant differences in water content at 12 and 24 hours after injury respectively between ketamine-treated group and control group [(77.34±2.35)% vs.(82.31±1.48)%;(78.01±2.21)%vs.(83.86±2.37)%,t=4.001 6,4.036 7,both P < 0.01]. ② Neuronal morphology: Pathological changes in traumatic region and peripheral region of injury in the ketamine-treated group were significantly lessened, and necrotic and apoptotic cells in the ketamine-treated group were also significantly reduced as compared with control group. ③ AQP-4 expression: AQP-4 positive neurons at each time point in the ketamine-treated group were significantly less than those in the control group. There were very significant differences in AQP-4 expression at 12 and 24 hours after injury between ketamine-treated group and control group [(34.17±4.74) /visual field vs. (43.42±5.65) /visual field;(40.83±3.17) /visual field vs. (58.88±6.23) /visual field,t =3.966 3,8.165 7, both P < 0.01]. ④ Neuronal apoptosis: TUNEL positive neurons at each time point in the ketamine-treated group were less than those in the control group. There were very significant differences in the neuronal apoptosis at 12 and 24 hours after injury between ketamine-treated group and control group [(26.25±3.04) /visual field vs. (32.75±4.39) /visual field;(29.33±4.02) /visual field vs. (39.83±5.61) /visual field,t=3.849 3,5.169 2,both P < 0.01].CONCLUSION: Ketamine can reduce brain edema, AQP-4 expression and neuronal apoptosis following brain injury in rats, and has obvious therapeutic effect on brain injury, especially at 12 and 24 hours after injury.展开更多
To investigate the effects of mRNA interference on aquaporin-4 expression in swollen tissue of rats with ischemic cerebral edema, and diagnose the significance of diffusion-weighted MRI, we injected 5 μL shRNA- aquap...To investigate the effects of mRNA interference on aquaporin-4 expression in swollen tissue of rats with ischemic cerebral edema, and diagnose the significance of diffusion-weighted MRI, we injected 5 μL shRNA- aquaporin-4 (control group) or siRNA- aquaporin-4 solution (1:800) (RNA interference group) into the rat right basal ganglia immediately before occlusion of the middle cerebral artery. At 0.25 hours after occlusion of the middle cerebral artery, diffusion-weighted MRI displayed a high signal; within 2 hours, the relative apparent diffusion coefficient decreased markedly, aquaporin-4 expression increased rapidly, and intracellular edema was obviously aggravated; at 4 and 6 hours, the relative apparent diffusion coefficient slowly returned to control levels, aquaporin-4 expression slightly increased, and angioedema was observed. In the RNA interference group, during 0.25- 6 hours after injection of siRNA- aquaporin-4 solution, the relative apparent diffusion coefficient slightly fluctuated and aquaporin-4 expression was upregulated; during 0.5-4 hours, the relative apparent diffusion coefficient was significantly higher, while aquaporin-4 expression was significantly lower when compared with the control group, and intracellular edema was markedly reduced; at 0.25 and 6 hours, the relative apparent diffusion coefficient and aquaporin-4 expression were similar when compared with the control group; obvious angioedema remained at 6 hours. Pearson's correlation test results showed that aquaporin-4 expression was negatively correlated with the apparent diffusion coefficient (r = -0.806, P < 0.01). These findings suggest that upregulated aquaporin-4 expression is likely to be the main molecular mechanism of intracellular edema and may be the molecular basis for decreased relative apparent diffusion coefficient. Aquaporin-4 gene interference can effectively inhibit the upregulation of aquaporin-4 expression during the stage of intracellular edema with time-effectiveness. Moreover, diffusion-weighted MRI can accurately detect intracellular edema.展开更多
Aquaporin-4 regulates water molecule channels and is important in tissue regulation and water transportation in the brain. Upregulation of aquaporin-4 expression is closely related to cellular edema after early cerebr...Aquaporin-4 regulates water molecule channels and is important in tissue regulation and water transportation in the brain. Upregulation of aquaporin-4 expression is closely related to cellular edema after early cerebral infarction. Cellular edema and aquaporin-4 expression can be determined by measuring cerebral infarct area and apparent diffusion coefficient using diffusion-weighted imaging(DWI). We examined the effects of silencing aquaporin-4 on cerebral infarction. Rat models of cerebral infarction were established by occlusion of the right middle cerebral artery and si RNA-aquaporin-4 was immediately injected via the right basal ganglia. In control animals, the area of high signal intensity and relative apparent diffusion coefficient value on T2-weighted imaging(T2WI) and DWI gradually increased within 0.5–6 hours after cerebral infarction. After aquaporin-4 gene silencing, the area of high signal intensity on T2 WI and DWI reduced, relative apparent diffusion coefficient value was increased, and cellular edema was obviously alleviated. At 6 hours after cerebral infarction, the apparent diffusion coefficient value was similar between treatment and model groups, but angioedema was still obvious in the treatment group. These results indicate that aquaporin-4 gene silencing can effectively relieve cellular edema after early cerebral infarction; and when conducted accurately and on time, the diffusion coefficient value and the area of high signal intensity on T2 WI and DWI can reflect therapeutic effects of aquaporin-4 gene silencing on cellular edema.展开更多
Ammonia induces astrocyte swelling, which is strongly associated with overexpression of aquaporin-4. However, the mechanisms by which ammonia induces astrocyte swelling, and subsequently upregulating aquaporin-4 expre...Ammonia induces astrocyte swelling, which is strongly associated with overexpression of aquaporin-4. However, the mechanisms by which ammonia induces astrocyte swelling, and subsequently upregulating aquaporin-4 expression, remain unknown. In the present study, astrocytes were cultured in vitro and exposed to ammonium chloride (NH4Cl), followed by propofol, protein kinase C agonist, or antagonist, respectively. Astrocyte morphology was observed by light microscopy, and aquaporin-4 expression was detected by western blot analysis. Results showed that propofol or protein kinase C agonist significantly attenuated the degree of NH4Cl-induced astrocyte swelling and inhibited increased aquaporin-4 expression. Propofol treatment inhibited aquaporin-4 overexpression in cultured astrocyte induced by NH4Cl; protein kinase C pathway activation is potentially involved.展开更多
BACKGROUND: Aquaporin-4 (AQP4) is abundant in astrocytes, ependymal cells, and the choroid plexus, and is associated with cerebrospinal fluid formation and osmoregulation. AQP4 is speculated to be the hypothalamic osm...BACKGROUND: Aquaporin-4 (AQP4) is abundant in astrocytes, ependymal cells, and the choroid plexus, and is associated with cerebrospinal fluid formation and osmoregulation. AQP4 is speculated to be the hypothalamic osmoreceptor and regulator of water balance. OBJECTIVE: To examine AQP4 expression and its role in cultured rat astrocytes after exposure to hypotonic medium. DESIGN, TIME AND SETTING: Randomized control experiment. This experiment was carried out in the Research Room of Neurobiology, Chongqing University of Medical Science, China, between April and October 2003. MATERIALS: Two-day-old newborn Wistar rats (n =20), weighing 10-15 g, were purchased from the Experimental Animal Center of Chongqing University of Medical Science, China. METHODS: Purified rat cerebral cortical astrocytes were isolated from Wistar rats for in vitro cell culture experiments. The cells were randomly divided into control and hypotonic groups. The in vitro cell edema model was established by exposing astrocytes to hypotonic medium (268, 254, or 240 mmol/L). Cells in the control group were cultured in normal culture medium. MAIN OUTCOME MEASURES: Morphological changes in astrocytes were observed under an inverted microscope and a transmission electron microscope after cells were cultured for 3, 6, 12, or 24 hours with hypotonic medium or normal culture medium. In each group, AQP4 protein and mRNA expression were assessed by immunocytochemistry, in situ hybridization, and reverse transcription polymerase chain reaction at the different time points. RESULTS: After astrocytes were cultured for 3, 6, 12, or 24 hours with hypotonic medium (268, 254, 240 mmol/L), they showed typical features of cell edema. In the control group, no astrocytes developed pathological changes. There were no significant changes in the AQP4 mRNA and protein expression in the control group at any of the time points after astrocytes were cultured with normal culture medium (P > 0.05). Compared with the control group, AQP4 mRNA and protein expression in the hypotonic group were remarkably increased at all time points after astrocytes cultured with hypotonic medium (268, 254, 240 mmol/L; P < 0.05). AQP4 mRNA and protein expression increased with increasing exposure time and with decreasing concentration of the hypotonic medium. CONCLUSION: Hypotonic medium induced cell edema and increased AQP4 mRNA and protein expression. Up-regulated expression of AQP4 was correlated with hypotonic medium concentration in a time dependent manner.展开更多
Recurrent epileptic seizures can lead to brain edema, indicating that water regulation may be perturbed by seizures. We hypothesized that the expression of the brain water channel aq-uaporin-4 (AQP-4) may be upregulat...Recurrent epileptic seizures can lead to brain edema, indicating that water regulation may be perturbed by seizures. We hypothesized that the expression of the brain water channel aq-uaporin-4 (AQP-4) may be upregulated in the epileptic brain. In the present study, we estab-lished the amygdala kindling model of epilepsy, and quantified AQP-4 protein and mRNA levels, using reverse transcription-PCR, immunohistochemistry and western blotting, in epileptic and control rats. We found that AQP-4 was overexpressed in the cerebral cortex of rats with epi-lepsy compared with controls. These findings show that AQP-4 is highly expressed in the brain of amygdala-kindled rats, suggesting that repeated seizures affect water homeostasis in the brain.展开更多
Taurine is concentrated in glial cells in the hypothalamus and released in an osmo-dependent manner through volume-sensitive anion channels. Released taurine acts on glycine receptors on vasopressin neurons to control...Taurine is concentrated in glial cells in the hypothalamus and released in an osmo-dependent manner through volume-sensitive anion channels. Released taurine acts on glycine receptors on vasopressin neurons to control vasopressin secretion. Water channel AQP4 is abundant in astrocytes in osmosensory areas such as the supraoptic nucleus of hypothalamus. An HPLC-based method was established to quantify taurine release from isolated hypothalamus tissues in wildtype and AQP4 knockout mice. Under the basal condition, there was no difference in taurine release from AQP4+/+ and AQP4–/– hypothalamuses. Taurine release from AQP4–/– hypothalamus under hypoosmotic stimulation was significantly lower than that from AQP4+/+ mice. AQP4 expression in the glial cells of the hypothalamus may play an important role in osmoregulation of taurine release and subsequent vasopressin secretion.展开更多
Cromakalim,an adenosine triphosphate-sensitive potassium channel opener,exhibits protective effects on cerebral ischemia/reperfusion injury.However,there is controversy as to whether this effect is associated with aqu...Cromakalim,an adenosine triphosphate-sensitive potassium channel opener,exhibits protective effects on cerebral ischemia/reperfusion injury.However,there is controversy as to whether this effect is associated with aquaporin-4 and blood-brain barrier permeability.Immunohistochemistry results show that preventive administration of cromakalim decreased aquaporin-4 and IgG protein expression in rats with ischemia/reperfusion injury;it also reduced blood-brain barrier permeability,and alleviated brain edema,ultimately providing neuroprotection.展开更多
BACKGROUND: Several studies have demonstrated that high doses of lidocaine can reduce edema in rats with brain injury by down-regulating aquaporin-4 (AQP4) expression. The hypothesis for the present study is that lido...BACKGROUND: Several studies have demonstrated that high doses of lidocaine can reduce edema in rats with brain injury by down-regulating aquaporin-4 (AQP4) expression. The hypothesis for the present study is that lidocaine could retinal edema that is associated with AQP4 expression. OBJECTIVE: This study was designed to investigate the interventional effects of lidocaine on retinal AQP4 expression and retinal edema following ischemia/reperfusion injury in the rat. DESIGN, TIME AND SETTING: This study, a randomized, controlled, animal experiment, was performed at the Basic Research Institute, Chongqing Medical University from September 2006 to May 2007. MATERIALS: Seventy-five, healthy, adult, female, Sprague-Dawley rats were included. A total of 50 rats were used to establish a retinal ischemia/reperfusion injury model using an anterior chamber enhancing perfusion unit. Rabbit anti-rat AQP4 antibody was purchased from Santa Cruz Biotechnology, USA. METHODS: All 75 rats were randomly divided into three groups, with 25 rats in each: control, model, and lidocaine. At each time point (1, 6, 12, 24, and 48 hours after modeling, five rats for each time point), each rat in the lidocaine group was intraperitoneally administered lidocaine with an initial dose of 30 mg/kg, followed by subsequent doses of 15 mg/kg every six hours. The entire treatment process lasted three days for each rat. At each above-mentioned time point, rats in the model group were modeled, but not administered any substances. Rats in the control group received the same treatments as in the lidocaine group except that lidocaine was replaceld by physiological saline. MAIN OUTCOME MEASURES: Following hematoxylin-eosin staining, rat retinal tissue was observed to investigate retinal edema degree through the use of an optical microscope and transmission electron microscope. Retinal AQP4 expression was determined by immunohistochemistry. RESULTS: At each above-mentioned time point, AQP4 expression was significantly increased in the model group compared to the control group (P < 0.05); this change was consistent with the degree of retinal edema. In the lidocaine group, retinal AQP4 expression was significantly decreased (P < 0.05), and retinal edema was reduced, compared with the model group. CONCLUSION: Lidocaine inhibits rat retinal AQP4 expression following ischemia/reperfusion injury, leading to a reduction of retinal edema.展开更多
BACKGROUND:Several studies have demonstrated that propofol exhibits protective effects in the central nervous system.OBJECTIVE:To observe the effects of propofol on neuronal apoptosis and aquaporin-4(AQP-4) expression...BACKGROUND:Several studies have demonstrated that propofol exhibits protective effects in the central nervous system.OBJECTIVE:To observe the effects of propofol on neuronal apoptosis and aquaporin-4(AQP-4) expression in a rat model of traumatic brain injury and to further investigate the mechanisms of action.DESIGN,TIME AND SETTING:The present neuronal,pathomorphological experiment was performed at the Institute of Cerebrovascular Disease,Qingdao University Medical College between April 2007 and March 2008.MATERIALS:Traumatic brain injury was induced by free falling objects in 150 healthy,male,Wistar rats.Propofol was produced by AstraZeneca,China.Rabbit anti-rat AQP-4 polyclonal antibody,SABC immunohistochemistry kit,and terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick-end labeling(TUNEL) kit were purchased from Wuhan Boster Bioengineering Co.,Ltd.,China.METHODS:All 150 rats were randomly and evenly divided into lesion-only and propofol-treated groups.One hour after traumatic brain injury,propofol-treated animals received 1% propofol(10 mg/kg) through the caudal vein,followed by a sustained perfusion of 30 mg/kg propofol per hour for 2 hours,while the lesion-only group received equal volumes of physiological saline in parallel.MAIN OUTCOME MEASURES:At 6,12,24,48,and 72 hours after traumatic brain injury,morphological changes in the peritraumatic and adjacent brain areas were analyzed in all rats by hematoxylin-eosin(HE) staining.In addition,cellular apoptosis was detected by TUNEL assay and the number of AQP-4-positive cells was determined by immunohistochemistry techniques.Brain water content was calculated as the ratio of dry to wet tissue weight.RESULTS:HE staining results demonstrated that,in the lesion-only group,the peritraumatic area exhibited neuronal and glial cell necrosis and disintegration.The adjacent area displayed swollen neuronal perikarya and vascular endothelial cells,cellular edema,and a small amount of proliferating glial cells.In contrast,these pathological changes were noticeably alleviated in the peritraumatic and adjacent areas of propofol-treated animals.Compared with the lesion-only group,the number of apoptotic cells was significantly decreased in the propofol-treated group at each time point after traumatic brain injury,in particular at 24 and 48 hours(P < 0.05-0.01).In the lesion-only group,AQP-4 expression began to increase at 6 hours after traumatic brain injury,reached a peak level at 24-48 hours,and began to decrease by 72 hours.In the propofol-treated group,the number of AQP-4 positive cells was significantly less than the lesion-only group.This was the case at all time points,in particular at 12 and 24 hours(P < 0.01-0.05).CONCLUSION:Propofol can downregulate neuronal apoptosis and AQP-4 expression in rats following traumatic brain injury,in particular at 24-48 hours.展开更多
BACKGROUND: Ischemic cerebrovascular disease causes injury to the blood-brain barrier. The occurrence of brain edema is associated with aquaporin expression following cerebral ischemia/reperfusion. OBJECTIVE: To analy...BACKGROUND: Ischemic cerebrovascular disease causes injury to the blood-brain barrier. The occurrence of brain edema is associated with aquaporin expression following cerebral ischemia/reperfusion. OBJECTIVE: To analyze the correlation of aquaporin-4 expression to brain edema and blood-brain barrier permeability in brain tissues of rat models of ischemia/reperfusion. DESIGN, TIME AND SETTING: The randomized control experiment was performed at the Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical College, China from December 2006 to October 2007. MATERIALS: A total of 112 adult, male, Sprague-Dawley rats, weighing 220-250 g, were used to establish rat models of middle cerebral artery occlusion and reperfusion by the suture method. Rabbit anti-aquaporin-4 (Santa Cruz, USA) and Evans blue (Sigma, USA) were used to analyze the tissue. METHODS: The rats were randomized into sham-operated (n = 16) and ischemia/reperfusion (n = 96) groups. There were 6 time points in the ischemia/reperfusion group, comprising 4, 6, 12, 24, 48, and 72 hours after reperfusion, with 16 rats for each time point. Rat models in the sham-operated group at 4 hours after surgery and rat models in the ischemia/reperfusion group at different time points were equally and randomly assigned into 4 different subgroups. MAIN OUTCOME MEASURES: Brain water content on the ischemic side and the control side was measured using the dry-wet weight method. Blood-brain barrier function was determined by Evans Blue. Aquaporin-4 expression surrounding the ischemic focus, as well as the correlation of aquaporin-4 expression with brain water content and Evans blue staining, were measured using immunohistochemistry and Western blot analysis. RESULTS: Brain water content on the ischemic side significantly increased at 12 hours after reperfusion, reached a peak at 48 hours, and was still high at 72 hours. Brain water content was greater on the ischemic hemispheres, compared with the control hemispheres at 6, 12, 24, 48, and 72 hours after reperfusion, as well as both hemispheres in the sham-operated group (P < 0.05). Evans blue content significantly increased on the ischemic side at 4 hours after ischemia/reperfusion, and reached a peak at 48 hours. Evans blue content was greater on the ischemic hemispheres, compared with the control hemispheres at various time points, as well as both hemispheres in the sham-operated group (P < 0.05). Aquaporin-4-positive cells were detected in the cortex and hippocampus, surrounding the ischemic penumbra focus, at 4-6 hours after ischemia/reperfusion. The number of positive cells significantly increased at 12 hours and reached a peak at 48-72 hours. Aquaporin-4 was, however, weakly expressed in the control hemispheres and the sham-operated group. The absorbance ratio of aquaporin-4 to β-actin was greater at 12, 24, 48, and 72 hours following cerebral ischemia/reperfusion, compared with the sham-operated group (P < 0.05). Aquaporin-4 expression positively correlated to brain water content and Evans blue staining following cerebral ischemia/reperfusion (r1 = 0.68, r2 = 0.81, P < 0.05). CONCLUSION: Aquaporin-4 is highly expressed in brain tissues, participates in the occurrence of ischemic brain edema, and is positively correlated to blood-brain barrier permeability following cerebral ischemia/reperfusion.展开更多
In this study,we recruited 10 neuromyelitis optica patients,two multiple sclerosis patients and two myelitis patients.Chinese hamster lung fibroblast (V79) cells transfected with a human aquaporin-4-mCherry fusion pro...In this study,we recruited 10 neuromyelitis optica patients,two multiple sclerosis patients and two myelitis patients.Chinese hamster lung fibroblast (V79) cells transfected with a human aquaporin-4-mCherry fusion protein gene were used to detect anti-aquaporin-4 antibody in neuromyelitis optica patient sera by immunofluorescence.Anti-aquaporin-4 autoantibody was stably detected by immunofluorescence in neuromyelitis optica patient sera exclusively.The sensitivity of the assay for neuromyelitis optica was 90% and the specificity for neuromyelitis optica was 100%.The anti-aquaporin-4 antibody titers in sera were tested with serial dilutions until the signal disappeared.A positive correlation was detected between Expanded Disability Status Scale scores and serum anti-aquaporin-4 antibody titers.The anti-aquaporin-4 antibody assay is highly sensitive and specific in the sera of Chinese neuromyelitis optica patients.Detection of aquaporin-4 autoantibody is important for the diagnosis and treatment of neuromyelitis optica.展开更多
文摘In the last decade,a new neurological disease concept known as anti-myelin oligodendrocyte glycoprotein antibody(MOG-IgG)-associated disease(MOGAD)has emerged and is currently one of the most focused research areas in the field of neuroimmunology.MOG is a membrane protein mainly expressed on the surface of oligodendrocytes(Zhou et al.,2006).The exact pathogenic role of MOG-IgG in patients with MOGAD remains unclear;however,MOG-IgG has been suggested to cause tissue alterations and damage MOG-expressing cells(Zhou et al.,2006).The pathogenicity of MOG-IgG is further supported by the observation that only a few patients with acquired central nervous system(CNS)demyelinating syndromes exhibit both anti-aquaporin-4 antibody(AQP4-IgG)and MOG-IgG simultaneously,particularly with clear positivity levels of these antibodies as indicated by a cell-based assay result with a titer≥1:100(Sechi et al.,2021;Banwell et al.,2023).
基金Hospital Level Project of Jiaxing First Hospital,No.2022-YB-034.
文摘BACKGROUND A case of neuromyelitis optica spectrum disorder(NMOSD)with positive cerebrospinal fluid(CSF)anti-aquaporin-4 antibody(AQP4-IgG)and anti-glial fibrillary acidic protein IgG(GFAP-IgG)at the time of relapse was reported.The exact roles of GFAP-IgG in NMOSD are not fully understood and are the subject of ongoing research.This study revealed the possible connection between GFAPIgG and the occurrence or development of diseases.CASE SUMMARY A 19-year-old woman was admitted to the hospital due to a constellation of symptoms,including dizziness,nausea,and vomiting that commenced 1 year prior,reoccurred 2 mo ago,and were accompanied by visual blurring that also began 2 mo ago.Additionally,she presented with slurred speech and ptosis,both of which emerged 1 mo ago.Notably,her symptoms deteriorated 10 d prior to admission,leading to the onset of arm and leg weakness.During hospitalization,magnetic resonance imaging showed high T2-fluid attenuated inversion recovery signals,and slightly high and equal diffusion-weighted imaging signals.The serum antibody of AQP4-IgG tested positive at a dilution of 1:100.CSF antibody testing showed positive results for GFAP-IgG at a dilution of 1:10 and AQP4-IgG at a dilution of 1:32.Based on these findings,the patient was diagnosed with NMOSD.She received intravenous methylprednisolone at a daily dose of 500 mg for 5 d,followed by a tapering-off period.Afterward,the rate of reduction was gradually slowed down and the timely use of immunosuppressants was implemented.CONCLUSION The CFS was slightly GFAP-IgG-positive during the relapse period,which can aid in the diagnosis and treatment of the disease.
基金the National Natural Science Foundation of China, No. 30470608, 30500171
文摘BACKGROUND: Aquaporin-4 (AQP-4), which is able to rapidly transport water within the brain, is highly expressed in brain tissue. It also plays an important role in the formation of cerebral edema following brain injury. However, the role of AQP-4 in the formation of cerebral edema following severe burns remains unknown. OBJECTIVE: To study changes in AQP-4 protein and mRNA expression during formation of cerebral edema following severe burns, and to explore the correlation between AQP-4 protein and mRNA expression with plasma levels of arginine vasopressin (AVP). DESIGN, TIME AND SETTING: A randomized, controlled, animal experiment was performed at the Research Center of Neuroscience, Chongqing Medical University from 2007 to 2008. MATERIALS: Biotin-labeled goat anti-rabbit antibody was provided by Beijing Zhongshan Biotechnology, China; in situ hybridization kit was provided by Wuhan Boster Biotechnology, China; rabbit anti-AQP-4 polyclonal antibody and horseradish peroxidase-labeled goat anti-rabbit IgG were provided by Chemicon, USA; AVP radioimmunoassay kit was provided by the Research Department of Neurobiology, the Second Military Medical University of Shanghai, China. METHODS: A total of 180 adult, healthy, Wistar rats were randomly assigned to control and burn groups with 30 rats in each group. The burn group was observed at five different time points: 2, 6, 12, 24, and 48 hours after burn. Hair on the mouse back was removed to expose skin on the back. After 1 day, skin with the hair removed was dipped into 100 °C water for 15 seconds to induce grade III burn injury that measures 30% of total burn surface area. MAIN OUTCOME MEASURES: Brain water content was measured using the dry-wet weight method. AQP-4 protein and mRNA expressions were detected using immunohistochemistry, in situ hybridization, Western blot, and reverse transcription-polymerase chain reaction; dynamic changes in plasma AVP were detected using radioimmunoassay. RESULTS: Brain water content gradually increased following severe burn injury. AQP-4 protein and mRNA expressions were upregulated in the supraoptic nucleus, suprachiasmatic nucleus, paraventricular nucleus, hippocampus, choroid plexus, and cerebral cortex. Plasma AVP levels increased following burn injury. AQP-4 protein and mRNA expressions positively correlated with brain water content and AVP levels during formation of cerebral edema (r = 0.870, 0.848, P < 0.01). CONCLUSION: AQP-4 participated in the formation of cerebral edema following burn injury. Plasma AVP upregulated AQP-4 expression in brain tissue, thereby promoting formation of cerebral edema.
文摘Objective: To characterize the expression of aquaporin-4 (AQP4), one of the aquaporins (AQPs), in human brain specimens from patients with traumatic brain injury or brain tumors. Methods: Nineteen human brain specimens were obtained from the patients with traumatic brain injury, brain tumors, benign meningioma or early stage hemorrhagic stroke. MRI or CT imaging was used to assess brain edema. Hematoxylin and eosin staining were used to evaluate cell damage. Immunohistochemistry was used to detect the AQP4 expression. Results: AQP4 expression was increased from 15h to at least 8 d after injury. AQP4immunoreactivity was strong around astrocytomas, ganglioglioma and metastatic adenocarcinoma. However, AQP4 immunoreactivity was only found in the centers of astrocytomas and ganglioglioma, but not in metastatic adenocarcinoma derived from lung.Conclusion: AQP4 expression increases in human brains after traumatic brain injury, within brain-derived tumors, and around brain tumors.
基金the National Natural Science Foundation of China,No. 30873391
文摘BACKGROUND:Aquaporin-4 (AQP-4) over-expression following cerebral ischemia results in cerebral edema. Picroside Ⅱ has been shown to exhibit a neuroprotective effect on neuronal apoptosis. However,few reports have addressed the neuroprotective mechanisms and therapeutic times following cerebral ischemic reperfusion injury. OBJECTIVE:To explore the neuroprotective effects and ideal treatment window for picroside II treatment of middle cerebral artery occlusion and reperfusion injury in rats. DESIGN,TIME AND SETTING:A randomized,controlled,animal experiment was performed at Institute of Cerebrovascular Diseases,Qingdao University Medical College from September 2008 to May 2009. MATERIALS:Picroside Ⅱ was purchased from Tianjin Kuiqing Medical Technology,China. METHODS:A total of 165 adult,healthy,male,Wistar rats were randomly assigned to sham-surgery (n = 15),model (n = 75),and treatment groups (n = 75). Rats in the model and treatment groups underwent middle cerebral artery occlusion and reperfusion through the use of an intraluminal monofilament suture on the left external-internal carotid artery. The treatment group was injected with 1.0% picroside Ⅱ (10 mg/kg) into the tail vein,and the model and sham-surgery groups were injected with 0.1 mol/L phosphate buffered saline (250 μL). MAIN OUTCOME MEASURES:Neurological functional scores were evaluated using the Longa's method; cerebral infarction volume was detected through the use of tetrazolium chloride staining; cellular apoptosis was determined through the use of the in situ end-labeling method; aquaporin-4 expression was measured using fluorescence labeling analysis and reverse transcription polymerase chain reaction technique. RESULTS:At 0.5 hour following cerebral ischemic injury,neurological functional scores were low,and a small infarction focus was detected in the ischemic cortex of the model group. Along with prolonged ischemia and an increased number of apoptosis-positive cells,AQP-4 mRNA and protein expression was increased. At 1-2 hours after ischemia,neurological scores and infarction sizes were significantly increased in the model group. Apoptotic-positive cells were widespread in the ipsilateral cortex and striatum. In addition,AQP-4 mRNA and protein expression levels were increased. Picroside Ⅱ treatment significantly decreased neurological scores and infarction volume,and reduced AQP-4 mRNA and protein expression levels compared with the model group (P < 0.05 or P < 0.01). At 1 hour after ischemia,the therapeutic effect of picroside Ⅱ was notable (P < 0.01). CONCLUSION:Picroside Ⅱ played a protective role in cerebral ischemic reperfusion injury by inhibiting apoptosis and regulating AQP-4 expression. The best therapeutic time window was 1 hour after cerebral ischemic reperfusion.
文摘Edema formation is a major problem following traumatic spinal cord injury(SCI) that acts to exacerbate secondary damage.Severity of edema correlates with reduced neurological outcome in human patients.To date, there are no effective treatments to directly resolve edema within the spinal cord.The aquaporin-4(AQP4) water channel is found on membranes of astrocytic endfeet in direct contact with blood vessels, the glia limitans in contact with the cerebrospinal fluid and ependyma around the central canal.Being so locally expressed at the interface between fluid and tissue allow AQP4 channels to play an important role in the bidirectional regulation of water homeostasis under normal conditions and following trauma.With the need to better understand the pathophysiology underlying the devastating cellular events in SCI, animal models have become an integral part of exploration.Inevitably, several injury models have been developed(contusion, compression, transection) resulting in difficult interpretation between studies with conflicting results.This is true in the case of understanding the role of AQP4 in the progression and resolution of edema following SCI, whose role is still not completely understood and is highly dependent on the type of edema present(vasogenic vs cytotoxic).Here, we discuss regulation of AQP4 in varying injury models and the effects of potential therapeutic interventions on expression, edema formation and functional recovery.Better understanding of the precise role of AQP4 following a wide range of injuries will help to understand optimal treatment timing following human SCI for prime therapeutic benefit and enhanced neurological outcome.
基金the National Natural Science Foundation of China,No.30825039,30973236,30872346,30770748Chinese Postdoctoral Training Grant,No. 20070420575+1 种基金Application Basic Research Foundation of Sichuan Province,No. 2008JY0131Youth Science and Technology Foundation of Sichuan Province,No. 07zq026-135
文摘BACKGROUND:Previous studies have demonstrated that aquaporin-4 (AQP4) plays a key role in the formation and resolution of brain edema.However,the molecular mechanisms and role of AQP4 in hypoxia-ischemia-induced brain edema remain poorly understood.OBJECTIVE:To establish a newborn animal model of astrocytic oxygen-glucose deprivation and reintroduction,to observe the correlation between AQP4 and cellular volume,and to investigate the role of AQP4 in the development of brain edema following oxygen deprivation and reintroduction.DESIGN,TIME AND SETTING:A comparative experiment was performed at the Experimental Center of West China Second University Hospital between October 2007 and April 2009.MATERIALS:Astrocytes were derived from the neocortex of Sprague Dawley rats aged 3 days.METHODS:Astrocytes were incubated in glucose/serum-free Dulbecco's modified Eagle's medium,followed by 1% oxygen for 6 hours.Finally,oxygen-glucose deprivation and reintroduction models were successfully established.MAIN OUTCOME MEASURES:Real-time polymerase chain reaction and Western blot analysis were used to measure expression of AQP4 mRNA and protein in cultured rat astrocytes following oxygen-glucose deprivation and reintroduction.Astrocytic cellular volume,as determined by [3H]-3-O-methyl-D-glucose,was used to represent the extent of astrocytic swelling.RESULTS:During oxygen-glucose deprivation,AQP4 mRNA and protein expression gradually decreased in astrocytes,whereas cellular volume increased in a time-dependent manner (P < 0.01).Following oxygen-glucose reintroduction,AQP4 mRNA and protein expression was upregulated,peaked at day 7,and then gradually decreased,but still higher than normal levels (P < 0.05).However,cellular volume gradually decreased (P < 0.01),and then reached normal levels at day 7.CONCLUSION:AQP4 expression highly correlated with cellular volume changes,suggesting that AQP4 played an important role in modulating brain water transport in an astrocytic oxygen-glucose deprivation and reintroduction model.
基金the Topic of Science and Technology Department of Qingdao City, No.2005kzd-22
文摘BACKGROUND: Aquaporin-4 (AQP-4) is closely related to the formation of brain edema. Neuronal apoptosis plays an important part in the conversion of swelled neuron following traumatic brain injury. At present, the studies on the protective effect of ketamine on brain have involved in its effect on aquaporin-4 expression and neuronal apoptosis in the brain tissues following brain injury in rats. OBJECTIVE: To observe the effect of ketamine on AQP-4 expression and neuronal apoptosis in the brain tissue following rat brain injury, and analyze the time-dependence of ketamine in the treatment of brain injury. DESIGN: Randomized grouping design, controlled animal trial.SETTING: Department of Anesthesiology, the Medical School Hospital of Qingdao University.MATERIALS: Totally 150 rats of clean grade, aged 3 months, were involved and randomized into control group and ketamine-treated group, with 75 rats in each. Each group was divided into 5 subgroups separately at 6,12, 24, 48 and 72 hours after injury, with 15 rats at each time point. Main instruments and reagents: homemade beat machine, ketamine hydrochloride (Hengrui Pharmaceutical Factory, Jiangsu), rabbit anti-rat AQP-4 polyclonal antibody, SABC immunohistochemical reagent kit and TUNEL reagent kit (Boster Co.,Ltd., Wuhan). METHODS: This trial was carried out in the Institute of Cerebrovascular Disease, Medical College of Qingdao University during March 2005 to February 2006. A weight-dropping rat model of brain injury was created with Feeney method. The rats in the ketamine-treated group were intraperitoneally administered with 50 g/L ketamine (120 mg/kg) one hour after injury, but ketamine was replaced by normal saline in the control group. In each subgroup, the water content of cerebral hemisphere was measured in 5 rats chosen randomly. The left 10 rats in each subgroup were transcardiacally perfused with ketamine, then the brain tissue was made into paraffin sections and stained by haematoxylin and eosin. Neuronal morphology was observed. AQP-4 expression and neuronal apoptosis were measured with immunohistochemical method and TUNEL method respectively. MAIN OUTCOME MEASURES: Water content in brain tissue, neuronal morphology, the number of AQP-4 positive neurons and TUNEL positive neurons in rats of two groups at each time point after injury.RESULTS: Totally 150 rats entered the stage of result analysis. ① Water content of brain tissue: The water content of brain tissue at each time point after injury in the ketamine-treated group was lower than that in the control group. There were very significant differences in water content at 12 and 24 hours after injury respectively between ketamine-treated group and control group [(77.34±2.35)% vs.(82.31±1.48)%;(78.01±2.21)%vs.(83.86±2.37)%,t=4.001 6,4.036 7,both P < 0.01]. ② Neuronal morphology: Pathological changes in traumatic region and peripheral region of injury in the ketamine-treated group were significantly lessened, and necrotic and apoptotic cells in the ketamine-treated group were also significantly reduced as compared with control group. ③ AQP-4 expression: AQP-4 positive neurons at each time point in the ketamine-treated group were significantly less than those in the control group. There were very significant differences in AQP-4 expression at 12 and 24 hours after injury between ketamine-treated group and control group [(34.17±4.74) /visual field vs. (43.42±5.65) /visual field;(40.83±3.17) /visual field vs. (58.88±6.23) /visual field,t =3.966 3,8.165 7, both P < 0.01]. ④ Neuronal apoptosis: TUNEL positive neurons at each time point in the ketamine-treated group were less than those in the control group. There were very significant differences in the neuronal apoptosis at 12 and 24 hours after injury between ketamine-treated group and control group [(26.25±3.04) /visual field vs. (32.75±4.39) /visual field;(29.33±4.02) /visual field vs. (39.83±5.61) /visual field,t=3.849 3,5.169 2,both P < 0.01].CONCLUSION: Ketamine can reduce brain edema, AQP-4 expression and neuronal apoptosis following brain injury in rats, and has obvious therapeutic effect on brain injury, especially at 12 and 24 hours after injury.
基金supported by the National Natural Science Foundation of China, No. 30960399, 81160181
文摘To investigate the effects of mRNA interference on aquaporin-4 expression in swollen tissue of rats with ischemic cerebral edema, and diagnose the significance of diffusion-weighted MRI, we injected 5 μL shRNA- aquaporin-4 (control group) or siRNA- aquaporin-4 solution (1:800) (RNA interference group) into the rat right basal ganglia immediately before occlusion of the middle cerebral artery. At 0.25 hours after occlusion of the middle cerebral artery, diffusion-weighted MRI displayed a high signal; within 2 hours, the relative apparent diffusion coefficient decreased markedly, aquaporin-4 expression increased rapidly, and intracellular edema was obviously aggravated; at 4 and 6 hours, the relative apparent diffusion coefficient slowly returned to control levels, aquaporin-4 expression slightly increased, and angioedema was observed. In the RNA interference group, during 0.25- 6 hours after injection of siRNA- aquaporin-4 solution, the relative apparent diffusion coefficient slightly fluctuated and aquaporin-4 expression was upregulated; during 0.5-4 hours, the relative apparent diffusion coefficient was significantly higher, while aquaporin-4 expression was significantly lower when compared with the control group, and intracellular edema was markedly reduced; at 0.25 and 6 hours, the relative apparent diffusion coefficient and aquaporin-4 expression were similar when compared with the control group; obvious angioedema remained at 6 hours. Pearson's correlation test results showed that aquaporin-4 expression was negatively correlated with the apparent diffusion coefficient (r = -0.806, P < 0.01). These findings suggest that upregulated aquaporin-4 expression is likely to be the main molecular mechanism of intracellular edema and may be the molecular basis for decreased relative apparent diffusion coefficient. Aquaporin-4 gene interference can effectively inhibit the upregulation of aquaporin-4 expression during the stage of intracellular edema with time-effectiveness. Moreover, diffusion-weighted MRI can accurately detect intracellular edema.
基金supported by the National Natural Science Foundation of China,No.30960399a grant from Hainan Provincial International Cooperation Project of China,No.Qiongke(2012)65a grant from Hainan Provincial Health Department Project of China,No.2011-SWK-10-136/Qiongwei2011-65
文摘Aquaporin-4 regulates water molecule channels and is important in tissue regulation and water transportation in the brain. Upregulation of aquaporin-4 expression is closely related to cellular edema after early cerebral infarction. Cellular edema and aquaporin-4 expression can be determined by measuring cerebral infarct area and apparent diffusion coefficient using diffusion-weighted imaging(DWI). We examined the effects of silencing aquaporin-4 on cerebral infarction. Rat models of cerebral infarction were established by occlusion of the right middle cerebral artery and si RNA-aquaporin-4 was immediately injected via the right basal ganglia. In control animals, the area of high signal intensity and relative apparent diffusion coefficient value on T2-weighted imaging(T2WI) and DWI gradually increased within 0.5–6 hours after cerebral infarction. After aquaporin-4 gene silencing, the area of high signal intensity on T2 WI and DWI reduced, relative apparent diffusion coefficient value was increased, and cellular edema was obviously alleviated. At 6 hours after cerebral infarction, the apparent diffusion coefficient value was similar between treatment and model groups, but angioedema was still obvious in the treatment group. These results indicate that aquaporin-4 gene silencing can effectively relieve cellular edema after early cerebral infarction; and when conducted accurately and on time, the diffusion coefficient value and the area of high signal intensity on T2 WI and DWI can reflect therapeutic effects of aquaporin-4 gene silencing on cellular edema.
基金Supported by a Grant from Zhejiang Provincial Health Department, No. 2007A057
文摘Ammonia induces astrocyte swelling, which is strongly associated with overexpression of aquaporin-4. However, the mechanisms by which ammonia induces astrocyte swelling, and subsequently upregulating aquaporin-4 expression, remain unknown. In the present study, astrocytes were cultured in vitro and exposed to ammonium chloride (NH4Cl), followed by propofol, protein kinase C agonist, or antagonist, respectively. Astrocyte morphology was observed by light microscopy, and aquaporin-4 expression was detected by western blot analysis. Results showed that propofol or protein kinase C agonist significantly attenuated the degree of NH4Cl-induced astrocyte swelling and inhibited increased aquaporin-4 expression. Propofol treatment inhibited aquaporin-4 overexpression in cultured astrocyte induced by NH4Cl; protein kinase C pathway activation is potentially involved.
基金the National Natural Science Foundation of China, No.30070247
文摘BACKGROUND: Aquaporin-4 (AQP4) is abundant in astrocytes, ependymal cells, and the choroid plexus, and is associated with cerebrospinal fluid formation and osmoregulation. AQP4 is speculated to be the hypothalamic osmoreceptor and regulator of water balance. OBJECTIVE: To examine AQP4 expression and its role in cultured rat astrocytes after exposure to hypotonic medium. DESIGN, TIME AND SETTING: Randomized control experiment. This experiment was carried out in the Research Room of Neurobiology, Chongqing University of Medical Science, China, between April and October 2003. MATERIALS: Two-day-old newborn Wistar rats (n =20), weighing 10-15 g, were purchased from the Experimental Animal Center of Chongqing University of Medical Science, China. METHODS: Purified rat cerebral cortical astrocytes were isolated from Wistar rats for in vitro cell culture experiments. The cells were randomly divided into control and hypotonic groups. The in vitro cell edema model was established by exposing astrocytes to hypotonic medium (268, 254, or 240 mmol/L). Cells in the control group were cultured in normal culture medium. MAIN OUTCOME MEASURES: Morphological changes in astrocytes were observed under an inverted microscope and a transmission electron microscope after cells were cultured for 3, 6, 12, or 24 hours with hypotonic medium or normal culture medium. In each group, AQP4 protein and mRNA expression were assessed by immunocytochemistry, in situ hybridization, and reverse transcription polymerase chain reaction at the different time points. RESULTS: After astrocytes were cultured for 3, 6, 12, or 24 hours with hypotonic medium (268, 254, 240 mmol/L), they showed typical features of cell edema. In the control group, no astrocytes developed pathological changes. There were no significant changes in the AQP4 mRNA and protein expression in the control group at any of the time points after astrocytes were cultured with normal culture medium (P > 0.05). Compared with the control group, AQP4 mRNA and protein expression in the hypotonic group were remarkably increased at all time points after astrocytes cultured with hypotonic medium (268, 254, 240 mmol/L; P < 0.05). AQP4 mRNA and protein expression increased with increasing exposure time and with decreasing concentration of the hypotonic medium. CONCLUSION: Hypotonic medium induced cell edema and increased AQP4 mRNA and protein expression. Up-regulated expression of AQP4 was correlated with hypotonic medium concentration in a time dependent manner.
基金the Natural Science Foundation of Shanghai, No. 09ZR1405500the Research Projects of Shanghai Municipal Health Bureau, No. 2008-08
文摘Recurrent epileptic seizures can lead to brain edema, indicating that water regulation may be perturbed by seizures. We hypothesized that the expression of the brain water channel aq-uaporin-4 (AQP-4) may be upregulated in the epileptic brain. In the present study, we estab-lished the amygdala kindling model of epilepsy, and quantified AQP-4 protein and mRNA levels, using reverse transcription-PCR, immunohistochemistry and western blotting, in epileptic and control rats. We found that AQP-4 was overexpressed in the cerebral cortex of rats with epi-lepsy compared with controls. These findings show that AQP-4 is highly expressed in the brain of amygdala-kindled rats, suggesting that repeated seizures affect water homeostasis in the brain.
基金Supported by the National Natural Science Foundation of China(Nos.30670477 and 30770493)
文摘Taurine is concentrated in glial cells in the hypothalamus and released in an osmo-dependent manner through volume-sensitive anion channels. Released taurine acts on glycine receptors on vasopressin neurons to control vasopressin secretion. Water channel AQP4 is abundant in astrocytes in osmosensory areas such as the supraoptic nucleus of hypothalamus. An HPLC-based method was established to quantify taurine release from isolated hypothalamus tissues in wildtype and AQP4 knockout mice. Under the basal condition, there was no difference in taurine release from AQP4+/+ and AQP4–/– hypothalamuses. Taurine release from AQP4–/– hypothalamus under hypoosmotic stimulation was significantly lower than that from AQP4+/+ mice. AQP4 expression in the glial cells of the hypothalamus may play an important role in osmoregulation of taurine release and subsequent vasopressin secretion.
基金the Shandong Provincial Science and Technology Program,No. 2006GG202004
文摘Cromakalim,an adenosine triphosphate-sensitive potassium channel opener,exhibits protective effects on cerebral ischemia/reperfusion injury.However,there is controversy as to whether this effect is associated with aquaporin-4 and blood-brain barrier permeability.Immunohistochemistry results show that preventive administration of cromakalim decreased aquaporin-4 and IgG protein expression in rats with ischemia/reperfusion injury;it also reduced blood-brain barrier permeability,and alleviated brain edema,ultimately providing neuroprotection.
文摘BACKGROUND: Several studies have demonstrated that high doses of lidocaine can reduce edema in rats with brain injury by down-regulating aquaporin-4 (AQP4) expression. The hypothesis for the present study is that lidocaine could retinal edema that is associated with AQP4 expression. OBJECTIVE: This study was designed to investigate the interventional effects of lidocaine on retinal AQP4 expression and retinal edema following ischemia/reperfusion injury in the rat. DESIGN, TIME AND SETTING: This study, a randomized, controlled, animal experiment, was performed at the Basic Research Institute, Chongqing Medical University from September 2006 to May 2007. MATERIALS: Seventy-five, healthy, adult, female, Sprague-Dawley rats were included. A total of 50 rats were used to establish a retinal ischemia/reperfusion injury model using an anterior chamber enhancing perfusion unit. Rabbit anti-rat AQP4 antibody was purchased from Santa Cruz Biotechnology, USA. METHODS: All 75 rats were randomly divided into three groups, with 25 rats in each: control, model, and lidocaine. At each time point (1, 6, 12, 24, and 48 hours after modeling, five rats for each time point), each rat in the lidocaine group was intraperitoneally administered lidocaine with an initial dose of 30 mg/kg, followed by subsequent doses of 15 mg/kg every six hours. The entire treatment process lasted three days for each rat. At each above-mentioned time point, rats in the model group were modeled, but not administered any substances. Rats in the control group received the same treatments as in the lidocaine group except that lidocaine was replaceld by physiological saline. MAIN OUTCOME MEASURES: Following hematoxylin-eosin staining, rat retinal tissue was observed to investigate retinal edema degree through the use of an optical microscope and transmission electron microscope. Retinal AQP4 expression was determined by immunohistochemistry. RESULTS: At each above-mentioned time point, AQP4 expression was significantly increased in the model group compared to the control group (P < 0.05); this change was consistent with the degree of retinal edema. In the lidocaine group, retinal AQP4 expression was significantly decreased (P < 0.05), and retinal edema was reduced, compared with the model group. CONCLUSION: Lidocaine inhibits rat retinal AQP4 expression following ischemia/reperfusion injury, leading to a reduction of retinal edema.
文摘BACKGROUND:Several studies have demonstrated that propofol exhibits protective effects in the central nervous system.OBJECTIVE:To observe the effects of propofol on neuronal apoptosis and aquaporin-4(AQP-4) expression in a rat model of traumatic brain injury and to further investigate the mechanisms of action.DESIGN,TIME AND SETTING:The present neuronal,pathomorphological experiment was performed at the Institute of Cerebrovascular Disease,Qingdao University Medical College between April 2007 and March 2008.MATERIALS:Traumatic brain injury was induced by free falling objects in 150 healthy,male,Wistar rats.Propofol was produced by AstraZeneca,China.Rabbit anti-rat AQP-4 polyclonal antibody,SABC immunohistochemistry kit,and terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick-end labeling(TUNEL) kit were purchased from Wuhan Boster Bioengineering Co.,Ltd.,China.METHODS:All 150 rats were randomly and evenly divided into lesion-only and propofol-treated groups.One hour after traumatic brain injury,propofol-treated animals received 1% propofol(10 mg/kg) through the caudal vein,followed by a sustained perfusion of 30 mg/kg propofol per hour for 2 hours,while the lesion-only group received equal volumes of physiological saline in parallel.MAIN OUTCOME MEASURES:At 6,12,24,48,and 72 hours after traumatic brain injury,morphological changes in the peritraumatic and adjacent brain areas were analyzed in all rats by hematoxylin-eosin(HE) staining.In addition,cellular apoptosis was detected by TUNEL assay and the number of AQP-4-positive cells was determined by immunohistochemistry techniques.Brain water content was calculated as the ratio of dry to wet tissue weight.RESULTS:HE staining results demonstrated that,in the lesion-only group,the peritraumatic area exhibited neuronal and glial cell necrosis and disintegration.The adjacent area displayed swollen neuronal perikarya and vascular endothelial cells,cellular edema,and a small amount of proliferating glial cells.In contrast,these pathological changes were noticeably alleviated in the peritraumatic and adjacent areas of propofol-treated animals.Compared with the lesion-only group,the number of apoptotic cells was significantly decreased in the propofol-treated group at each time point after traumatic brain injury,in particular at 24 and 48 hours(P < 0.05-0.01).In the lesion-only group,AQP-4 expression began to increase at 6 hours after traumatic brain injury,reached a peak level at 24-48 hours,and began to decrease by 72 hours.In the propofol-treated group,the number of AQP-4 positive cells was significantly less than the lesion-only group.This was the case at all time points,in particular at 12 and 24 hours(P < 0.01-0.05).CONCLUSION:Propofol can downregulate neuronal apoptosis and AQP-4 expression in rats following traumatic brain injury,in particular at 24-48 hours.
基金the Scientific Research Foundation of Health Department of Jiangsu Province of China, No. H9908the International Communication Program of Education Department of Jiangsu Province of China in 2007
文摘BACKGROUND: Ischemic cerebrovascular disease causes injury to the blood-brain barrier. The occurrence of brain edema is associated with aquaporin expression following cerebral ischemia/reperfusion. OBJECTIVE: To analyze the correlation of aquaporin-4 expression to brain edema and blood-brain barrier permeability in brain tissues of rat models of ischemia/reperfusion. DESIGN, TIME AND SETTING: The randomized control experiment was performed at the Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical College, China from December 2006 to October 2007. MATERIALS: A total of 112 adult, male, Sprague-Dawley rats, weighing 220-250 g, were used to establish rat models of middle cerebral artery occlusion and reperfusion by the suture method. Rabbit anti-aquaporin-4 (Santa Cruz, USA) and Evans blue (Sigma, USA) were used to analyze the tissue. METHODS: The rats were randomized into sham-operated (n = 16) and ischemia/reperfusion (n = 96) groups. There were 6 time points in the ischemia/reperfusion group, comprising 4, 6, 12, 24, 48, and 72 hours after reperfusion, with 16 rats for each time point. Rat models in the sham-operated group at 4 hours after surgery and rat models in the ischemia/reperfusion group at different time points were equally and randomly assigned into 4 different subgroups. MAIN OUTCOME MEASURES: Brain water content on the ischemic side and the control side was measured using the dry-wet weight method. Blood-brain barrier function was determined by Evans Blue. Aquaporin-4 expression surrounding the ischemic focus, as well as the correlation of aquaporin-4 expression with brain water content and Evans blue staining, were measured using immunohistochemistry and Western blot analysis. RESULTS: Brain water content on the ischemic side significantly increased at 12 hours after reperfusion, reached a peak at 48 hours, and was still high at 72 hours. Brain water content was greater on the ischemic hemispheres, compared with the control hemispheres at 6, 12, 24, 48, and 72 hours after reperfusion, as well as both hemispheres in the sham-operated group (P < 0.05). Evans blue content significantly increased on the ischemic side at 4 hours after ischemia/reperfusion, and reached a peak at 48 hours. Evans blue content was greater on the ischemic hemispheres, compared with the control hemispheres at various time points, as well as both hemispheres in the sham-operated group (P < 0.05). Aquaporin-4-positive cells were detected in the cortex and hippocampus, surrounding the ischemic penumbra focus, at 4-6 hours after ischemia/reperfusion. The number of positive cells significantly increased at 12 hours and reached a peak at 48-72 hours. Aquaporin-4 was, however, weakly expressed in the control hemispheres and the sham-operated group. The absorbance ratio of aquaporin-4 to β-actin was greater at 12, 24, 48, and 72 hours following cerebral ischemia/reperfusion, compared with the sham-operated group (P < 0.05). Aquaporin-4 expression positively correlated to brain water content and Evans blue staining following cerebral ischemia/reperfusion (r1 = 0.68, r2 = 0.81, P < 0.05). CONCLUSION: Aquaporin-4 is highly expressed in brain tissues, participates in the occurrence of ischemic brain edema, and is positively correlated to blood-brain barrier permeability following cerebral ischemia/reperfusion.
基金supported by a grant from the China-Italy Bilateral Cooperation in Science and Technology Committee,No.PGR00011
文摘In this study,we recruited 10 neuromyelitis optica patients,two multiple sclerosis patients and two myelitis patients.Chinese hamster lung fibroblast (V79) cells transfected with a human aquaporin-4-mCherry fusion protein gene were used to detect anti-aquaporin-4 antibody in neuromyelitis optica patient sera by immunofluorescence.Anti-aquaporin-4 autoantibody was stably detected by immunofluorescence in neuromyelitis optica patient sera exclusively.The sensitivity of the assay for neuromyelitis optica was 90% and the specificity for neuromyelitis optica was 100%.The anti-aquaporin-4 antibody titers in sera were tested with serial dilutions until the signal disappeared.A positive correlation was detected between Expanded Disability Status Scale scores and serum anti-aquaporin-4 antibody titers.The anti-aquaporin-4 antibody assay is highly sensitive and specific in the sera of Chinese neuromyelitis optica patients.Detection of aquaporin-4 autoantibody is important for the diagnosis and treatment of neuromyelitis optica.
