Objective: To investigate the effect of crocin carotenoid on BNDF and CREB gene expression in the brain ventral tegmental area(VTA) and the serum level of BDNF in morphine-treated rats compared to control. Methods: In...Objective: To investigate the effect of crocin carotenoid on BNDF and CREB gene expression in the brain ventral tegmental area(VTA) and the serum level of BDNF in morphine-treated rats compared to control. Methods: In this study, 40 male Wistar rats(200-250 g) were used in 5 experimental groups: 1) non morphine treat rats(control); 2) non morphine-treated rats with 25 mg/kg crocin carotenoid(i.p., for 21 d); 3) morphine treated rats(10 mg/kg twice a day, s.c., 21 d); 4 and 5) morphine-treated rats with 12.5 and 25 mg/kg crocin carotenoid, respectively. By the end of research, BDNF and CREB expression was determined by real-time-PCR method. ELISA analysis was also applied for assessing the serum BDNF level. Results: The data indicated that morphine treatment could cause a significant decrease in BDNF and CREB gene expression(P<0.01 and P<0.001, respectively) in brain VTA as well as serum level of BDNF(P<0.01) in comparison to control group. Treatment with 25 mg/kg crocin carotenoid caused a significant enhancement in BDNF and CREF gene expression(P<0.01 and P<0.05, respectively) and serum level of BDNF(P<0.01) in morphine-treated rats in comparison to morphine-treated group. Conclusions: Regarding to obtained results, crocin carotenoid can inhibit unfavorable effects of morphine on the neural system to some extent through enhancing BDNF and CREB gene expression in brain VTA and serum level of BDNF.展开更多
Neurons in the laterodorsal tegmentum (LDTg) and pedunculopontine tegmental nucleus (PPTg) play important roles in central autonomic circuits of the kidney. In this study, we used a combination of retrograde tracers p...Neurons in the laterodorsal tegmentum (LDTg) and pedunculopontine tegmental nucleus (PPTg) play important roles in central autonomic circuits of the kidney. In this study, we used a combination of retrograde tracers pseudorabies virus (PRV)-614 and fluorescence immunohistochemistry to characterize the neuroanatomic substrate of PPTg and LDTg innervating the kidney in the mouse. PRV-614-infected neurons were retrogradely labeled in the rostral and middle parts of LDTg, and the middle and caudal parts of PPTg after tracer injection in the kidney. PRV-614/TPH double-labeled neurons were mainly localized in the rostral of LDTg, whereas PRV-614/TH neurons were scattered within the three parts of LDTg. PRV-614/TPH and PRV-614/TH neurons were located predominantly in the caudal of PPTg (cPPTg). These data provided direct neuroanatomical foundation for the identification of serotonergic and catecholaminergic projections from the mid-brain tegmentum to the kidney.展开更多
Prior work has shown that systemic cocaine pretreatment augments cocaine conditioned place preference (CPP) in rats. In contrast, ghrelin receptor antagonism attenuates cocaine and amphetamine-induced CPP. In order to...Prior work has shown that systemic cocaine pretreatment augments cocaine conditioned place preference (CPP) in rats. In contrast, ghrelin receptor antagonism attenuates cocaine and amphetamine-induced CPP. In order to further investigate ghrelin’s role in dopamine-mediated reward, the present report examined whether pretreament with ghrelin, administered directly into the ventral tegmental area (VTA) of the midbrain, would potentiate the rewarding properties of cocaine as measured by CPP. Adult male Sprague-Dawley rats were given access to either side of the CPP chamber in order to determine initial side preferences. The rats were then restricted to either their non-preferred or preferred side over the course of conditioning which lasted for a total of 16 consecutive days. This was followed by a final test day to then reassess preference. On days where rats were confined to their non-preferred side, ghrelin (30-300 pmol) and cocaine (0.625-10 mg/kg IP) were administered immediately prior to the conditioning trial. On alternate days rats were treated with vehicle and placed into what was initially determined to be their preferred side. CPP was calculated as the difference in percentage of total time spent in the treatment-paired compartment during the post-conditioning session and the pre-conditioning session. Our results indicated that both cocaine and ghrelin elicited CPP and that ghrelin pretreatment potentiated the effect of cocaine on place preference. Overall, these findings provide additional support for the argument that ghrelin signaling within the VTA enhances the rewarding effects of psychostimulant compounds.展开更多
Rapid eye movement(REM)sleep behavior disorder(RBD)is a parasomnia that is featured by elevated motor behaviors and dream enactments during REM sleep.Clinical observations show that RBD bears significant relevance wit...Rapid eye movement(REM)sleep behavior disorder(RBD)is a parasomnia that is featured by elevated motor behaviors and dream enactments during REM sleep.Clinical observations show that RBD bears significant relevance with several synucleinopathies such as Lewy body dementia and Parkinson disease(PD),and often develops prior to their diagnosis.Being a potential biomarker of PD,investigating the relationship of RBD symptoms and their emergence in developing PD would provide insight intoits pathogenesis.Here,in a chronic model of PD,rats with daily rotenone treatment exhibited key RBD features,including elevated sleep muscle tone,sleep fragmentation and EEG slowing at different time points.Based on detectedearly alpha synuclein aggregation and neural apoptosis in the sublaterodorsal tegmental nucleus(SLD),an area known to promote REM sleep and maintain sleep muscle atonia,the possible involvement of SLD glutamatergic neurons was interrogated.Via chemogenetic activation of SLD glutamatergic neurons,key RBD symptoms and EEG slowing in REM sleep were alleviated.These results are consistent with a progressive degeneration in REM sleep promoting pathways.Our findings provide a foundation for further studies into RBD and its relationship to neurodegenerative diseases.展开更多
Methylphenidate (MPD) is considered as the first-line pharmacotherapy to treat ADHD. More recently, MPD has also been used as a cognitive enhancement recreationally. Its therapeutic effects are not fully understood, n...Methylphenidate (MPD) is considered as the first-line pharmacotherapy to treat ADHD. More recently, MPD has also been used as a cognitive enhancement recreationally. Its therapeutic effects are not fully understood, nor are the long term effects of the drug on brain development. The ventral tegmental area (VTA) neuronal activity was recorded from freely behaving adolescent rats using a wireless recording system. Five groups were used: saline, 0.6, 2.5, 5.0 and 10.0 mg/kg MPD. The experiment lasted for 10 days. This study demonstrated that VTA neurons respond to MPD in a dose response characteristic and the same dose of MPD can cause both behavioral sensitization and behavioral tolerance. The neuronal unit activity was evaluated based on the animals’ behavioral activity following chronic MPD administration. The study showed that the animals’ behavioral response to different acute MPD of 0.6, 2.5 and 10.0 mg/kg doses responded in a dose response characteristics. Moreover, the same chronic dose of 0.6, 2.5, and 10.0 mg/kg MPD elicits in some animals’ behavioral sensitization and in some others behavioral tolerance. Therefore, the neuronal activity recorded from animals expressing behavioral sensitization was analyzed separately from the neuronal activity recorded from of behaviorally tolerant animals and it was found that the VTA units of the behaviorally sensitization animals responded significantly different to the drug than those VTA units recorded from animals expressing behavioral tolerance.展开更多
The mesolimbic dopamine system consisting of dopaminergic neurons projecting from the ventral tegmental area (VTA) to the nucleus accumbens (N.Acc.) mediates the reinforcing effects of addictive drugs including alcoho...The mesolimbic dopamine system consisting of dopaminergic neurons projecting from the ventral tegmental area (VTA) to the nucleus accumbens (N.Acc.) mediates the reinforcing effects of addictive drugs including alcohol. Given that VTA is a heterogeneous area and that alcohol, in rather low doses, interacts directly with ligand-gated ion channels, we hypothesised that low, rather than high, doses of alcohol into the VTA activate the mesolimbic dopamine system and that alcohol may have different effects in the anterior and posterior parts of the VTA. The present study was undertaken to investigate this hypothesis. The present series of experiment show that infusion of a low dose of alcohol (20 mM) into the anterior, but not posterior, part of the VTA increases accumbal dopamine release in rats. In addition, higher doses of alcohol (100 or 300 mM) into the anterior or posterior part of the VTA do not affect the release of dopamine in the N.Acc., suggesting that low doses of alcohol can activate the mesolimbic dopamine system via mechanisms in the VTA. These data contribute to understanding the neuronal mechanisms underlying the dependence-producing properties of alcohol and could tentatively contribute to that new treatment strategies for alcohol use disorder can be developed.展开更多
Chronic pain often develops severe mood changes such as depression.However,how chronic pain leads to depression remains elusive and the mechanisms determining individuals’responses to depression are largely unexplore...Chronic pain often develops severe mood changes such as depression.However,how chronic pain leads to depression remains elusive and the mechanisms determining individuals’responses to depression are largely unexplored.Here we found that depression-like behaviors could only be observed in 67.9%of mice with chronic neuropathic pain,leaving 32.1%of mice with depression resilience.We determined that the spike discharges of the ventral tegmental area(VTA)-projecting lateral habenula(LHb)glutamatergic(Glu)neurons were sequentially increased in sham,resilient and susceptible mice,which consequently inhibited VTA dopaminergic(DA)neurons through a LHbGlu-VTAGABA-VTADA circuit.Furthermore,the LHbGlu-VTADA excitatory inputs were dampened via GABAB receptors in a pre-synaptic manner.Regulation of LHb-VTA pathway largely affected the development of depressive symptoms caused by chronic pain.Our study thus identifies a pivotal role of the LHb-VTA pathway in coupling chronic pain with depression and highlights the activity-dependent contribution of LHbGlu-to-VTADA inhibition in depressive behavioral regulation.展开更多
Brain-derived neurotrophic factor is a key factor in stress adaptation and avoidance of a social stress behavioral response.Recent studies have shown that brain-derived neurotrophic factor expression in stressed mice ...Brain-derived neurotrophic factor is a key factor in stress adaptation and avoidance of a social stress behavioral response.Recent studies have shown that brain-derived neurotrophic factor expression in stressed mice is brain region–specific,particularly involving the corticolimbic system,including the ventral tegmental area,nucleus accumbens,prefrontal cortex,amygdala,and hippocampus.Determining how brain-derived neurotrophic factor participates in stress processing in different brain regions will deepen our understanding of social stress psychopathology.In this review,we discuss the expression and regulation of brain-derived neurotrophic factor in stress-sensitive brain regions closely related to the pathophysiology of depression.We focused on associated molecular pathways and neural circuits,with special attention to the brain-derived neurotrophic factor–tropomyosin receptor kinase B signaling pathway and the ventral tegmental area–nucleus accumbens dopamine circuit.We determined that stress-induced alterations in brain-derived neurotrophic factor levels are likely related to the nature,severity,and duration of stress,especially in the above-mentioned brain regions of the corticolimbic system.Therefore,BDNF might be a biological indicator regulating stress-related processes in various brain regions.展开更多
Dopaminergic neurons in the ventral tegmental area(VTA)play an important role in cognition,emergence from anesthesia,reward,and aversion,and their projection to the cortex is a crucial part of the"bottom-up"...Dopaminergic neurons in the ventral tegmental area(VTA)play an important role in cognition,emergence from anesthesia,reward,and aversion,and their projection to the cortex is a crucial part of the"bottom-up"ascending activating system.The prelimbic cortex(PrL)is one of the important projection regions of the VTA.However,the roles of dopaminergic neurons in the VTA and the VTADA–PrL pathway under sevoflurane anesthesia in rats remain unclear.In this study,we found that intraperitoneal injection and local microinjection of a dopamine D1 receptor agonist(Chloro-APB)into the PrL had an emergence-promoting effect on sevoflurane anesthesia in rats,while injection of a dopamine D1 receptor antagonist(SCH23390)deepened anesthesia.The results of chemogenetics combined with microinjection and optogenetics showed that activating the VTADA–PrL pathway prolonged the induction time and shortened the emergence time of anesthesia.These results demonstrate that the dopaminergic system in the VTA has an emergence-promoting effect and that the bottom-up VTADA–PrL pathway facilitates emergence from sevoflurane anesthesia.展开更多
Anxiety is a common disease in the modern society which significantly affects people’s daily lives and function,thus it has become an increasingly highlighted issue.Anxiety is regulated by neural circuits in the brai...Anxiety is a common disease in the modern society which significantly affects people’s daily lives and function,thus it has become an increasingly highlighted issue.Anxiety is regulated by neural circuits in the brain.Therefore,the basal mechanism of anxiety has been studied,especially research based on the related neural circuits.For a long time,due to the limitations of science and technology,there was no breakthrough in research regarding anxiety.However,in recent years,due to the progress of technology,the research on anxiety neural circuits has made great progress.For example,the interaction among various brain regions,such as the central nucleus of the amygdala(CeA),the ventral tegmental area(VTA),the ventral hippocampus(vHPC),and so on.This article focuses on three brain regions:including BLA,BNST,and VTA,and illustrate their different roles and mechanisms in regulating anxiety.On this basis,this intensive study of anxiety will further promote the progress of anxiety research and provide therapeutic targets for the related treatment.展开更多
Objective The aim of the present study was not only to assess the retrograde degenerative changes in the dopaminergic neurons of the substantia nigra （SN） and ventral tegmental area （VTA） after injection of 6-hydr...Objective The aim of the present study was not only to assess the retrograde degenerative changes in the dopaminergic neurons of the substantia nigra （SN） and ventral tegmental area （VTA） after injection of 6-hydroxydopamine （6-OHDA） into the striatum, but also to use this 6-OHDA model of Parkinson＇s disease to explore the possible neuroprotective effect of R-apomorphine （R-APt）. Methods The partial lesion was obtained by intrastriatal administration of 6-OHDA. R- APt administration （10 mg/kg, s.c.） started 15 min prior to lesioning and continued daily for another 22 days post surgery. Testing was carried out 5 weeks after lesioning. We investigated the histology and associated behavior and neurochemical changes. Structural and functional deficits were quantified by tyrosine hydroxylase （TH） / Nissl-staining cell number counting, striatal dopamine （DA） content determination and amphetamine-induced rotation analysis. Results R-APt- treatment attenuated the amphetamine-induced ipsiversive rotation 5 weeks after the lesion induction. R-APt administra- tion for 22 days significantly reduced the size of the lesion at the level of the SN from 50% （control group） to 69%. Moreover, the cell shape resembled that observed in the intact animals. R-APt treatment significantly increased the number of cells in both the lesion and the intact sides of VTA by 60%, suggesting selective neurotrophic effect of R-APt in this area. Finally, R-APt-treatment significantly attenuated the 6-OHDA-induced striatal DA depletion and normalized dihydroxyphenylacetic acid （DOPAC）/DA ratios. Conclusion We conclude that R-APt has neuroprotective and pos- sible neurotrophic effect on a striatal lesion with 6-OHDA, suggesting that this drug may have rescuing properties in patients with early stage Parkinson＇s disease. These effects are more pronounced in VTA and enhance with duration of treatment.展开更多
Up to 20%of women experience stress-related disorders during the postpartum period;however,little is known about the specific neural circuitry by which maternal stress exerts its negative impacts on mental health and ...Up to 20%of women experience stress-related disorders during the postpartum period;however,little is known about the specific neural circuitry by which maternal stress exerts its negative impacts on mental health and maternal caregiving behavior.Theoretically,such a circuitry should serve as an interface between the stress response system and maternal neural network,transmitting stress signals to the neural circuitry that mediates maternal behavior.In this paper,I propose that the lateral habenula(LHb)serves this interface function.Evidence shows that the LHb plays a key role in encoding stress-induced effects and in the pathophysiology of major depression and stressrelated anxiety,and thus may play a role in maternal behavior as part of the maternal brain network.I hypothesize that maternal stress acts upon the LHb and two of its major downstream targets,i.e.,ventral tegmental area(VTA)and dorsal raphe nucleus(DRN),compromising the maternal care and contributing to postpartum mental disorders.This hypothesis makes three predictions:(1)maternal stress enhances LHb neuronal activity;(2)activation of DRN-and VTA-projecting neurons in the LHb mimics the detrimental effects of maternal stress on maternal behavior;and(3)suppression of DRN-and VTA-projecting neurons in the LHb attenuates the detrimental effects of maternal stress on maternal care in stressed mothers.Confirmation of this hypothesis is expected to enhance our understanding of the neurocircuit mechanisms mediating stress effects on maternal behavior.展开更多
In the present article, the author proposes a new “D-cell hypothesis” for mesolimbic dopamine (DA) hyperactivity of schizophrenia, of which relevant molecular mechanism has not yet been known. The “D-cell” is defi...In the present article, the author proposes a new “D-cell hypothesis” for mesolimbic dopamine (DA) hyperactivity of schizophrenia, of which relevant molecular mechanism has not yet been known. The “D-cell” is defined as “the non-monoaminergic aromatic L-amino acid decarboxylase (AADC)-containing cell”. The D-cell contains AADC but not dopaminergic nor serotonergic. D-cells produce trace amines, and also take up amine precursors and convert them to amines by decarboxylation. The author reported “dopa-decarboxylating neurons specific to the human striatum”, that is, “D-neurons” in the human striatum, and preliminarily the number reduction of D-neurons in the striatum and nucleus accumbens of postmortem brains of patients with schizophrenia. Trace amine-associated receptor, type 1 (TAAR1), a subtype of trace amine receptors, having a large number of ligands, including tyramine, β-phenylethylamine (PEA), and methamphetamine, is a target receptor for the latest neuroleptic discovery. Recent studies have shown that the decreased stimulation of TAAR1 on cell membranes or nerve terminals of DA neurons in the midbrain ventral tegmental area (VTA) increased firing frequency of VTA DA neurons. In brains of schizophrenia, dysfunction of neural stem cells in the subventricular zone of lateral ventricle may cause reduction of the number of D-neurons in the striatum and nucleus accumbens, and may result in decrease of trace amine synthesis. The decrease of stimulation of TAAR1 on terminals of VTA DA neurons caused by trace amine reduction may increase firing frequency of VTA DA neurons, and may finally cause mesolimbic DA hyperactivity. This innovative theory, “D-cell hypothesis” might explain mesolimbic DA hyperactivity in pathogenesis of schizophrenia.展开更多
The author proposes a new “D-cell hypothesis” for mesolimbic dopamine (DA) hyperactivity of schizophrenia. The “D-cell” is defined as “non-monoaminergic aromatic L-amino acid decarboxylase (AADC)-containing cell...The author proposes a new “D-cell hypothesis” for mesolimbic dopamine (DA) hyperactivity of schizophrenia. The “D-cell” is defined as “non-monoaminergic aromatic L-amino acid decarboxylase (AADC)-containing cell”. D-cells produce trace amines, such as tyramine and β-phenylethylamine, and may also take up amine precursors and convert them to amines by decarboxylation. Trace amine-associated receptor, type 1 (TAAR1), a subtype of trace amine receptors, has a large number of ligands, including tyramine, β-phenylethylamine and methamphetamine, that influence on human mental states, and is now regarded to be a target receptor for novel neuroleptics. Recent studies revealed that the reduced stimulation of TAAR1 on DA neurons in the midbrain ventral tegmental area (VTA) increased firing frequency of VTA DA neurons. The author and her colleagues reported the decrease of D-neurons in the striatum and nucleus accumbens of postmortem brains of patients with schizophrenia. This may imply the decrease of trace amine synthesis, resulting the reduced stimulation of TAAR1 on terminals of midbrain VTA DA neurons, and may lead to mesolimbic DA hyperactivity in schizophrenia. The decrease of striatal D-neurons of postmortem brains of schizophrenia is supposed to be due to neural stem cell dysfunction in the subventricular zone of lateral ventricle. The decrease of striatal D-neurons and acts of TAAR1 signals on DA neurons-might explain mesolimbic DA hyperactivity of schizophrenia.展开更多
Neural stem cell (NSC) hypofunction is an etiological hypothesis of schizophrenia. Although dopamine (DA) dysfunction is also a widely accepted hypothesis, molecular background of mesolimbic DA hyperactivity has not y...Neural stem cell (NSC) hypofunction is an etiological hypothesis of schizophrenia. Although dopamine (DA) dysfunction is also a widely accepted hypothesis, molecular background of mesolimbic DA hyperactivity has not yet been well known. Here, the author proposes “D-cell hypothesis”, accounting for molecular basis of mesolimbic DA hyperactivity of schizophrenia, by NSC hypofunction and decrease of putative NSC-induced D-cells. The “D-cell” is defined as “non-monoaminergic aromatic L-amino acid decarboxylase (AADC)-containing cell”. D-cells produce trace amines, and also take up amine precursors and convert them to amines by decarboxylation. The author reported “dopa-decarboxylating neurons specific to the human striatum”, that is, “D-neurons” in the human striatum, and decrease of striatal D-neurons in patients with schizophrenia. Trace amine-associated receptor, type 1 (TAAR1), a subtype of trace amine receptors, having a quite number of ligands such as tyramine, β-phenylethylamine (PEA) and methamphetamine, has modulating functions on monoamine neurons. It has been known that reduced binding of ligands to TAAR1 receptors on DA terminal of DA neurons of the midbrain ventral tegmental area (VTA) increased firing frequency of VTA DA neurons. In brains of schizophrenia, NSC hypofunction in the subventricular zone of lateral ventricle may cause decrease of D-neurons in the striatum and nucleus accumbens, and may result in decrease of trace amine signals. Decrease of trace amine signals to TAAR1 on VTA DA neurons may increase firing frequency of VTA DA neurons, and may finally cause mesolimbic DA hyperactivity. Increased stimulation to DA D2 receptors of NSCs might suppress NSC proliferation, and may induce additional mesolimbic DA hyperactivity as well as D-cell decrease. This novel theory, “D-cell hypothesis”, possibly explains mesolimbic DA hyperactivity in pathogenesis of schizophrenia.展开更多
OBJECTIVE Dopamine(DA)plays important roles in Pavlovian conditioning by mediating reward,learning and motivation.While the conditioning stimulation(CS) is the most important inducement for reinstatement in addiction....OBJECTIVE Dopamine(DA)plays important roles in Pavlovian conditioning by mediating reward,learning and motivation.While the conditioning stimulation(CS) is the most important inducement for reinstatement in addiction.The present study investigated the specific role of the DA projections to nucleus accumbens(NAc) and medial prefrontal cortices(mPFC) from ventral tegmental area(VTA) in reinstatement induced by cue.METHODS(1)Optogenetic intracranial self-stimulation and reinstatement.DAT-Cre transgenic mice received an injection of adeno-associated viral vectors encoding channelrhodopsin2(ChR2) or control vector into the VTA resulting in the selective expression of these opsins in DA neurons.Then,we stimulated the VTA,NAc(core and shel) or mP FC [prelimbic cortex(PL) and infralimbic cortex(IL)] via an optical fiber.In the reinforcement test,the mice with ChR2 learned instrumental responses corresponding to the delivery of photostimulation into the VTA with multiple frequencies and during time;in the reinstatement phase,stimulation of the DA projections to NAc(core or shell) or mPFC(IL and PL) from VTA to induce reinstatement after 2 weeks of extinction of self-stimulation.(2)Reinstatement in cocaine self-administration.Virus encoding ChR2 or hM4 Di were injected into VTA of DAT-Cre transgenic mice.The mice with ChR2 and hM4 Di in DA neurons were trained to establish self-administration of cocaine.After 2 weeks of extinction,laser stimulation of the DA projections to NAc(core or shel) or mP FC(IL and PL) was conducted to induce reinstatement.After that,Clozapine was injected in NAc core to test the impacts of VTA-NAc core depression on the reinstatement induced by cue.(3) Photometry of VTA DA neurons in reinstatement.DAT-Cre transgenic mice were received an injection of AAV-DIO-Gcamp6 m into VTA.After cocaine self-administration and extinction,mice with Gcamp6 m were challenged by cue(paired with cocaine previously) and the photometry of VTA DA neurons was conducted during the reinstatement.RESULTS(1)The enhanced self-stimulation behavior was positive correlation with the stimulation of DA neurons in VTA according to the increasing frequency of stimulation and extent stimulation duration time.Furthermore,DA receptor antagonists significantly depressed the frequency curve.(2) Only stimulation of the projections to the NAc core from the VTA significantly induced reinstatement after extinction of self-stimulation,neither shell nor mPFC(PL or IL).(3) Depression of VTA-NAc core projection significantly inhibited the reinstatement induced by cue.(4) DA neurons in VTA were activated when the cue appeared during the period of reinstatement test.CONCLUSION Mesocorticolimbic DA system directly modulate the reinforcement dependant on DA receptor.The activity of DA neurons in VTA is necessary for cue induced relapse.Importantly,projections to NAc core from VTA perform the unique effects in reinstatement.展开更多
BACKGROUND： Drug addiction involves two main central nervous systems, namely the dopamine and noradrenaline systems. These systems are primarily distributed in five brain regions： the ventral tegmental area, the nuc...BACKGROUND： Drug addiction involves two main central nervous systems, namely the dopamine and noradrenaline systems. These systems are primarily distributed in five brain regions： the ventral tegmental area, the nucleus accumbens, the prefrontal cortex, the hippocampus, and the locus coeruleus. OBJECTIVE： To investigate regional changes of guanine nucleotide binding protein-inhabitant 2 （Gi2） in dopaminergic and noradrenergic neurons in brains of morphine-tolerant and -dependent rats. DESIGN, TIME, AND SETTING： A randomized control study was performed at the Department of Neurobiology in the Second Military Medical University of Chinese PLA （Shanghai, China） between September 2002 and March 2004. MATERIALS： Thirty-six, healthy, male, Sprague-Dawley （SD） rats were used to establish morphine-dependent models. Morphine hydrochloride was a product of Shenyang First Pharmaceutical Factory （China）; naloxone hydrochloride was a product of Beijing Four-Ring Pharmaceutical Factory （China）; and α subunit of Gi2 antibody was offered by Santa Cruz Biotechnology, lnc （USA）. METHODS： Thirty-six SD rats were randomly divided into six groups （n = 6）： （1） acute morphine-dependent group, （2） acute abstinent group, （3） acute control group, （4） chronic morphine-dependent group, （5） chronic abstinent group, and （6） chronic control group. Rats in the acute morphine-dependent and the acute groups were injected with morphine （5 mg/kg）, one injection every two hours, for a total of eight injections. In the acute and chronic morphine-dependent rat models, morphine withdrawal syndrome was precipitated by an injection of naloxone （5 mg/kg）. Rats in the acute control group were given a peritoneal injection of physiological saline at the same administration time as the above two groups. Rats in the chronic morphine-dependent and chronic abstinent groups were injected with morphine three times per day. The administration dose on day 1 was initially 5 mg/kg at 20：00, which increased by 5 mg/kg at 8：00, 12：00, and 20：00 until day 7. On day 13, the dose continuously increased by 10 mg/kg until a chronic morphine-dependent rat model was successfully induced. Afterwards, the rats presented with withdrawal syndromes on naloxone （5 mg/kg） at 8：00 on the same day. Rats in the chronic control group were injected with physiological saline at the same time of the two chronic groups. MAIN OUTCOME MEASURES： The concentration of Gi2 protein in the five brain regions （ventral tegmental area, nucleus accumbens, prefrontal cortex, locus coeruleus, and hippocampus） was detected by immunohistochemistry. RESULTS： In the acute morphine-dependent and acute abstinent groups, Gi2 protein concentration was significantly decreased in the nucleus accumbens, compared to the acute control group （P 〈 0.01）, while no obvious changes were detected in other brain regions. In the chronic morphine-dependent and chronic abstinent groups, Gi2 protein concentration was significantly decreased in the nucleus accumbens, but significantly increased in the locus coeruleus （P 〈 0.01 ） compared to the chronic control group. CONCLUSION： Morphine dependence and tolerance may induce obvious reductions of Gi2 protein levels in the nucleus accumbens of rats. Chronic morphine dependence desensitizes the homologous neurons.展开更多
Recent pharmacological discovery on trace amine-associated receptor, type 1(TAAR1) has emphasized importance of trace amines in pathogenesis of psychoses, such as schizophrenia. TAAR1 has many ligands, including tyram...Recent pharmacological discovery on trace amine-associated receptor, type 1(TAAR1) has emphasized importance of trace amines in pathogenesis of psychoses, such as schizophrenia. TAAR1 has many ligands, including tyramine, β-phenylethylamine (PEA), amphetamines, and 3’-iodothyronamine. So-called D-neurons are putative producer of trace amines, endogenous ligands of TAAR1. The D-neuron is defined “the aromatic L-amino acid decarboxylase (AADC)-containing neuron, but not dopaminergic nor serotonergic”, i.e. not containing tyrosine hydroxylase nor tryptophan hydroxylase. AADC is an enzyme, also called dopa decarboxylase (DDC). The localization of D-neurons in the central nervous system has been specified into 15 groups, from the spinal cord (D1) to striatum (D15). We showed the decrease of D-neurons in D15 in postmortem brains of schizophrenia, where midbrain dopamine (DA) neurons are heavily innervated. Decrease of D-neurons may cause reduction of trace amines in the striatum, and may also decrease stimulation of TAAR1 on striatal terminals of ventral tegmental area (VTA) DA neurons. This might increase firing frequency of VTA DA neurons, and causes DA hyperactivity in the striatum and nucleus accumbens. In the present article, the author introduces the novel theory, “D-cell hypothesis”, for mesolimbic DA hyperactivity of schizophrenia. Some clinical and/or experimental evidences that support this hypothesis are mentioned. The D-neuron, as a trace amine producer, is a clue for elucidating pathogenesis of psychoses, as well as human mental functions. Thus, signal transduction of D-neurons should be investigated.展开更多
Itch is an unpleasant sensation that provokes the desire to scratch.While acute itch serves as a protec-tive system to warn the body of external irritating agents,chronic itch is a debilitating but poorly-treated clin...Itch is an unpleasant sensation that provokes the desire to scratch.While acute itch serves as a protec-tive system to warn the body of external irritating agents,chronic itch is a debilitating but poorly-treated clinical dis-ease leading to repetitive scratching and skin lesions.How-ever,the neural mechanisms underlying the pathophysiol-ogy of chronic itch remain mysterious.Here,we identified a cell type-dependent role of the anterior cingulate cortex(ACC)in controlling chronic itch-related excessive scratch-ing behaviors in mice.Moreover,we delineated a neural circuit originating from excitatory neurons of the ACC to the ventral tegmental area(VTA)that was critically involved in chronic itch.Furthermore,we demonstrate that the ACC→VTA circuit also selectively modulated histaminergic acute itch.Finally,the ACC neurons were shown to predomi-nantly innervate the non-dopaminergic neurons of the VTA.Taken together,our findings uncover a cortex-midbrain cir-cuit for chronic itch-evoked scratching behaviors and shed novel insights on therapeutic intervention.展开更多
Objective To observe the effect of acupuncture stimulation of the sacral segment on the excitability of the cerebral cortex and the activity of the urinary bladder and the involvement of the cholinergic neurons in the...Objective To observe the effect of acupuncture stimulation of the sacral segment on the excitability of the cerebral cortex and the activity of the urinary bladder and the involvement of the cholinergic neurons in the laterodorsal tegmental （LDT） nucleus of the brainstem in acupuncture-induced electroencephalogram （EEG） changes. Methods A total of 109 SD rats were used in the present study. Under anesthesia （urethane）, a pair of stainless steel electrodes was separately implanted into the frontal and parietal bony sutures to record EEG. Glass microelectrodes were used to record extracellular discharges of single neuron of the LDT nucleus in the brainstem. Urinary bladder pressure was recorded through a catheter inserted in the bladder and the contraction was induced by infusion of normal saline. A filiform acupuncture needle was inserted into the sacral segment Ecorresponding to Zhongliao （中髎BL 33）] and rotated manually for 1 min. Results In 27 rats whose bladder was full of normal saline, acupuncture stimulation of the sacral region suppressed the contraction activity of the bladder, the fast EEG with lower amplitude and higher frequency tuned into slow EEG with higher amplitude and lower frequency in 6 cases （22.2%）. The inhibitory effect occurred from 45 s to 12 min after acupuncture manipulation. In 82 rats whose bladder was empty, acupuncture stimulation caused the fast EEG to turn into slow EEG in 71 cases （86.6%）. Simultaneously, LDT cholinergic neurons reduced their firing rates from （2.9±1.5） Hz to （1.2±0.6） Hz （n = 12, P〈0.05）, and the reduction of LDT neuronal discharge was earlier in time than the change of EEG. Conclusion Acupuncture stimulation of the sacral region can lower the excitability of the cerebral cortex and suppress bladder activity, which is closely associated with its resultant inhibitory effect on the electrical activity of LDT cholinergic neurons.展开更多
基金supported by a grant from the Rafsanjan University of Medical Sciences(20/341/1395)
文摘Objective: To investigate the effect of crocin carotenoid on BNDF and CREB gene expression in the brain ventral tegmental area(VTA) and the serum level of BDNF in morphine-treated rats compared to control. Methods: In this study, 40 male Wistar rats(200-250 g) were used in 5 experimental groups: 1) non morphine treat rats(control); 2) non morphine-treated rats with 25 mg/kg crocin carotenoid(i.p., for 21 d); 3) morphine treated rats(10 mg/kg twice a day, s.c., 21 d); 4 and 5) morphine-treated rats with 12.5 and 25 mg/kg crocin carotenoid, respectively. By the end of research, BDNF and CREB expression was determined by real-time-PCR method. ELISA analysis was also applied for assessing the serum BDNF level. Results: The data indicated that morphine treatment could cause a significant decrease in BDNF and CREB gene expression(P<0.01 and P<0.001, respectively) in brain VTA as well as serum level of BDNF(P<0.01) in comparison to control group. Treatment with 25 mg/kg crocin carotenoid caused a significant enhancement in BDNF and CREF gene expression(P<0.01 and P<0.05, respectively) and serum level of BDNF(P<0.01) in morphine-treated rats in comparison to morphine-treated group. Conclusions: Regarding to obtained results, crocin carotenoid can inhibit unfavorable effects of morphine on the neural system to some extent through enhancing BDNF and CREB gene expression in brain VTA and serum level of BDNF.
基金supported by grants from National Natural Science Foundation of China(No.81071307,No.30872440,No.81171259)
文摘Neurons in the laterodorsal tegmentum (LDTg) and pedunculopontine tegmental nucleus (PPTg) play important roles in central autonomic circuits of the kidney. In this study, we used a combination of retrograde tracers pseudorabies virus (PRV)-614 and fluorescence immunohistochemistry to characterize the neuroanatomic substrate of PPTg and LDTg innervating the kidney in the mouse. PRV-614-infected neurons were retrogradely labeled in the rostral and middle parts of LDTg, and the middle and caudal parts of PPTg after tracer injection in the kidney. PRV-614/TPH double-labeled neurons were mainly localized in the rostral of LDTg, whereas PRV-614/TH neurons were scattered within the three parts of LDTg. PRV-614/TPH and PRV-614/TH neurons were located predominantly in the caudal of PPTg (cPPTg). These data provided direct neuroanatomical foundation for the identification of serotonergic and catecholaminergic projections from the mid-brain tegmentum to the kidney.
文摘Prior work has shown that systemic cocaine pretreatment augments cocaine conditioned place preference (CPP) in rats. In contrast, ghrelin receptor antagonism attenuates cocaine and amphetamine-induced CPP. In order to further investigate ghrelin’s role in dopamine-mediated reward, the present report examined whether pretreament with ghrelin, administered directly into the ventral tegmental area (VTA) of the midbrain, would potentiate the rewarding properties of cocaine as measured by CPP. Adult male Sprague-Dawley rats were given access to either side of the CPP chamber in order to determine initial side preferences. The rats were then restricted to either their non-preferred or preferred side over the course of conditioning which lasted for a total of 16 consecutive days. This was followed by a final test day to then reassess preference. On days where rats were confined to their non-preferred side, ghrelin (30-300 pmol) and cocaine (0.625-10 mg/kg IP) were administered immediately prior to the conditioning trial. On alternate days rats were treated with vehicle and placed into what was initially determined to be their preferred side. CPP was calculated as the difference in percentage of total time spent in the treatment-paired compartment during the post-conditioning session and the pre-conditioning session. Our results indicated that both cocaine and ghrelin elicited CPP and that ghrelin pretreatment potentiated the effect of cocaine on place preference. Overall, these findings provide additional support for the argument that ghrelin signaling within the VTA enhances the rewarding effects of psychostimulant compounds.
基金The project supported by the HKGRCGRF gran(t14111715)
文摘Rapid eye movement(REM)sleep behavior disorder(RBD)is a parasomnia that is featured by elevated motor behaviors and dream enactments during REM sleep.Clinical observations show that RBD bears significant relevance with several synucleinopathies such as Lewy body dementia and Parkinson disease(PD),and often develops prior to their diagnosis.Being a potential biomarker of PD,investigating the relationship of RBD symptoms and their emergence in developing PD would provide insight intoits pathogenesis.Here,in a chronic model of PD,rats with daily rotenone treatment exhibited key RBD features,including elevated sleep muscle tone,sleep fragmentation and EEG slowing at different time points.Based on detectedearly alpha synuclein aggregation and neural apoptosis in the sublaterodorsal tegmental nucleus(SLD),an area known to promote REM sleep and maintain sleep muscle atonia,the possible involvement of SLD glutamatergic neurons was interrogated.Via chemogenetic activation of SLD glutamatergic neurons,key RBD symptoms and EEG slowing in REM sleep were alleviated.These results are consistent with a progressive degeneration in REM sleep promoting pathways.Our findings provide a foundation for further studies into RBD and its relationship to neurodegenerative diseases.
文摘Methylphenidate (MPD) is considered as the first-line pharmacotherapy to treat ADHD. More recently, MPD has also been used as a cognitive enhancement recreationally. Its therapeutic effects are not fully understood, nor are the long term effects of the drug on brain development. The ventral tegmental area (VTA) neuronal activity was recorded from freely behaving adolescent rats using a wireless recording system. Five groups were used: saline, 0.6, 2.5, 5.0 and 10.0 mg/kg MPD. The experiment lasted for 10 days. This study demonstrated that VTA neurons respond to MPD in a dose response characteristic and the same dose of MPD can cause both behavioral sensitization and behavioral tolerance. The neuronal unit activity was evaluated based on the animals’ behavioral activity following chronic MPD administration. The study showed that the animals’ behavioral response to different acute MPD of 0.6, 2.5 and 10.0 mg/kg doses responded in a dose response characteristics. Moreover, the same chronic dose of 0.6, 2.5, and 10.0 mg/kg MPD elicits in some animals’ behavioral sensitization and in some others behavioral tolerance. Therefore, the neuronal activity recorded from animals expressing behavioral sensitization was analyzed separately from the neuronal activity recorded from of behaviorally tolerant animals and it was found that the VTA units of the behaviorally sensitization animals responded significantly different to the drug than those VTA units recorded from animals expressing behavioral tolerance.
基金grants from the Swedish Research Council (grant no. K2006-21X-04247-33-3 and 2009-2782)The Swedish brain foundation, LUA/ALF (grant no. 148251)
文摘The mesolimbic dopamine system consisting of dopaminergic neurons projecting from the ventral tegmental area (VTA) to the nucleus accumbens (N.Acc.) mediates the reinforcing effects of addictive drugs including alcohol. Given that VTA is a heterogeneous area and that alcohol, in rather low doses, interacts directly with ligand-gated ion channels, we hypothesised that low, rather than high, doses of alcohol into the VTA activate the mesolimbic dopamine system and that alcohol may have different effects in the anterior and posterior parts of the VTA. The present study was undertaken to investigate this hypothesis. The present series of experiment show that infusion of a low dose of alcohol (20 mM) into the anterior, but not posterior, part of the VTA increases accumbal dopamine release in rats. In addition, higher doses of alcohol (100 or 300 mM) into the anterior or posterior part of the VTA do not affect the release of dopamine in the N.Acc., suggesting that low doses of alcohol can activate the mesolimbic dopamine system via mechanisms in the VTA. These data contribute to understanding the neuronal mechanisms underlying the dependence-producing properties of alcohol and could tentatively contribute to that new treatment strategies for alcohol use disorder can be developed.
基金This work was supported by the National Natural Science Foundation of China(32192410,32071000,81870866,81571074,82230037,81971226,81620108008,82130034)the Foundation for Distinguished Young Scholars of ShaanXi(2019JC-21,2021JC-33)+1 种基金Young Scholar Project of the First Affiliated Hospital of Nanchang University(YFYPY202109)the Boost Plan of Xijing Hospital(XJZT21J01).
文摘Chronic pain often develops severe mood changes such as depression.However,how chronic pain leads to depression remains elusive and the mechanisms determining individuals’responses to depression are largely unexplored.Here we found that depression-like behaviors could only be observed in 67.9%of mice with chronic neuropathic pain,leaving 32.1%of mice with depression resilience.We determined that the spike discharges of the ventral tegmental area(VTA)-projecting lateral habenula(LHb)glutamatergic(Glu)neurons were sequentially increased in sham,resilient and susceptible mice,which consequently inhibited VTA dopaminergic(DA)neurons through a LHbGlu-VTAGABA-VTADA circuit.Furthermore,the LHbGlu-VTADA excitatory inputs were dampened via GABAB receptors in a pre-synaptic manner.Regulation of LHb-VTA pathway largely affected the development of depressive symptoms caused by chronic pain.Our study thus identifies a pivotal role of the LHb-VTA pathway in coupling chronic pain with depression and highlights the activity-dependent contribution of LHbGlu-to-VTADA inhibition in depressive behavioral regulation.
基金supported financially by the National Natural Science Foundation of China,No.82071272(to YZ).
文摘Brain-derived neurotrophic factor is a key factor in stress adaptation and avoidance of a social stress behavioral response.Recent studies have shown that brain-derived neurotrophic factor expression in stressed mice is brain region–specific,particularly involving the corticolimbic system,including the ventral tegmental area,nucleus accumbens,prefrontal cortex,amygdala,and hippocampus.Determining how brain-derived neurotrophic factor participates in stress processing in different brain regions will deepen our understanding of social stress psychopathology.In this review,we discuss the expression and regulation of brain-derived neurotrophic factor in stress-sensitive brain regions closely related to the pathophysiology of depression.We focused on associated molecular pathways and neural circuits,with special attention to the brain-derived neurotrophic factor–tropomyosin receptor kinase B signaling pathway and the ventral tegmental area–nucleus accumbens dopamine circuit.We determined that stress-induced alterations in brain-derived neurotrophic factor levels are likely related to the nature,severity,and duration of stress,especially in the above-mentioned brain regions of the corticolimbic system.Therefore,BDNF might be a biological indicator regulating stress-related processes in various brain regions.
基金supported by the National Natural Science Foundation of China(81801366 and 82001453)and the National Key R&D Program of China(2018YFC2001901).
文摘Dopaminergic neurons in the ventral tegmental area(VTA)play an important role in cognition,emergence from anesthesia,reward,and aversion,and their projection to the cortex is a crucial part of the"bottom-up"ascending activating system.The prelimbic cortex(PrL)is one of the important projection regions of the VTA.However,the roles of dopaminergic neurons in the VTA and the VTADA–PrL pathway under sevoflurane anesthesia in rats remain unclear.In this study,we found that intraperitoneal injection and local microinjection of a dopamine D1 receptor agonist(Chloro-APB)into the PrL had an emergence-promoting effect on sevoflurane anesthesia in rats,while injection of a dopamine D1 receptor antagonist(SCH23390)deepened anesthesia.The results of chemogenetics combined with microinjection and optogenetics showed that activating the VTADA–PrL pathway prolonged the induction time and shortened the emergence time of anesthesia.These results demonstrate that the dopaminergic system in the VTA has an emergence-promoting effect and that the bottom-up VTADA–PrL pathway facilitates emergence from sevoflurane anesthesia.
文摘Anxiety is a common disease in the modern society which significantly affects people’s daily lives and function,thus it has become an increasingly highlighted issue.Anxiety is regulated by neural circuits in the brain.Therefore,the basal mechanism of anxiety has been studied,especially research based on the related neural circuits.For a long time,due to the limitations of science and technology,there was no breakthrough in research regarding anxiety.However,in recent years,due to the progress of technology,the research on anxiety neural circuits has made great progress.For example,the interaction among various brain regions,such as the central nucleus of the amygdala(CeA),the ventral tegmental area(VTA),the ventral hippocampus(vHPC),and so on.This article focuses on three brain regions:including BLA,BNST,and VTA,and illustrate their different roles and mechanisms in regulating anxiety.On this basis,this intensive study of anxiety will further promote the progress of anxiety research and provide therapeutic targets for the related treatment.
文摘Objective The aim of the present study was not only to assess the retrograde degenerative changes in the dopaminergic neurons of the substantia nigra （SN） and ventral tegmental area （VTA） after injection of 6-hydroxydopamine （6-OHDA） into the striatum, but also to use this 6-OHDA model of Parkinson＇s disease to explore the possible neuroprotective effect of R-apomorphine （R-APt）. Methods The partial lesion was obtained by intrastriatal administration of 6-OHDA. R- APt administration （10 mg/kg, s.c.） started 15 min prior to lesioning and continued daily for another 22 days post surgery. Testing was carried out 5 weeks after lesioning. We investigated the histology and associated behavior and neurochemical changes. Structural and functional deficits were quantified by tyrosine hydroxylase （TH） / Nissl-staining cell number counting, striatal dopamine （DA） content determination and amphetamine-induced rotation analysis. Results R-APt- treatment attenuated the amphetamine-induced ipsiversive rotation 5 weeks after the lesion induction. R-APt administra- tion for 22 days significantly reduced the size of the lesion at the level of the SN from 50% （control group） to 69%. Moreover, the cell shape resembled that observed in the intact animals. R-APt treatment significantly increased the number of cells in both the lesion and the intact sides of VTA by 60%, suggesting selective neurotrophic effect of R-APt in this area. Finally, R-APt-treatment significantly attenuated the 6-OHDA-induced striatal DA depletion and normalized dihydroxyphenylacetic acid （DOPAC）/DA ratios. Conclusion We conclude that R-APt has neuroprotective and pos- sible neurotrophic effect on a striatal lesion with 6-OHDA, suggesting that this drug may have rescuing properties in patients with early stage Parkinson＇s disease. These effects are more pronounced in VTA and enhance with duration of treatment.
文摘Up to 20%of women experience stress-related disorders during the postpartum period;however,little is known about the specific neural circuitry by which maternal stress exerts its negative impacts on mental health and maternal caregiving behavior.Theoretically,such a circuitry should serve as an interface between the stress response system and maternal neural network,transmitting stress signals to the neural circuitry that mediates maternal behavior.In this paper,I propose that the lateral habenula(LHb)serves this interface function.Evidence shows that the LHb plays a key role in encoding stress-induced effects and in the pathophysiology of major depression and stressrelated anxiety,and thus may play a role in maternal behavior as part of the maternal brain network.I hypothesize that maternal stress acts upon the LHb and two of its major downstream targets,i.e.,ventral tegmental area(VTA)and dorsal raphe nucleus(DRN),compromising the maternal care and contributing to postpartum mental disorders.This hypothesis makes three predictions:(1)maternal stress enhances LHb neuronal activity;(2)activation of DRN-and VTA-projecting neurons in the LHb mimics the detrimental effects of maternal stress on maternal behavior;and(3)suppression of DRN-and VTA-projecting neurons in the LHb attenuates the detrimental effects of maternal stress on maternal care in stressed mothers.Confirmation of this hypothesis is expected to enhance our understanding of the neurocircuit mechanisms mediating stress effects on maternal behavior.
文摘In the present article, the author proposes a new “D-cell hypothesis” for mesolimbic dopamine (DA) hyperactivity of schizophrenia, of which relevant molecular mechanism has not yet been known. The “D-cell” is defined as “the non-monoaminergic aromatic L-amino acid decarboxylase (AADC)-containing cell”. The D-cell contains AADC but not dopaminergic nor serotonergic. D-cells produce trace amines, and also take up amine precursors and convert them to amines by decarboxylation. The author reported “dopa-decarboxylating neurons specific to the human striatum”, that is, “D-neurons” in the human striatum, and preliminarily the number reduction of D-neurons in the striatum and nucleus accumbens of postmortem brains of patients with schizophrenia. Trace amine-associated receptor, type 1 (TAAR1), a subtype of trace amine receptors, having a large number of ligands, including tyramine, β-phenylethylamine (PEA), and methamphetamine, is a target receptor for the latest neuroleptic discovery. Recent studies have shown that the decreased stimulation of TAAR1 on cell membranes or nerve terminals of DA neurons in the midbrain ventral tegmental area (VTA) increased firing frequency of VTA DA neurons. In brains of schizophrenia, dysfunction of neural stem cells in the subventricular zone of lateral ventricle may cause reduction of the number of D-neurons in the striatum and nucleus accumbens, and may result in decrease of trace amine synthesis. The decrease of stimulation of TAAR1 on terminals of VTA DA neurons caused by trace amine reduction may increase firing frequency of VTA DA neurons, and may finally cause mesolimbic DA hyperactivity. This innovative theory, “D-cell hypothesis” might explain mesolimbic DA hyperactivity in pathogenesis of schizophrenia.
文摘The author proposes a new “D-cell hypothesis” for mesolimbic dopamine (DA) hyperactivity of schizophrenia. The “D-cell” is defined as “non-monoaminergic aromatic L-amino acid decarboxylase (AADC)-containing cell”. D-cells produce trace amines, such as tyramine and β-phenylethylamine, and may also take up amine precursors and convert them to amines by decarboxylation. Trace amine-associated receptor, type 1 (TAAR1), a subtype of trace amine receptors, has a large number of ligands, including tyramine, β-phenylethylamine and methamphetamine, that influence on human mental states, and is now regarded to be a target receptor for novel neuroleptics. Recent studies revealed that the reduced stimulation of TAAR1 on DA neurons in the midbrain ventral tegmental area (VTA) increased firing frequency of VTA DA neurons. The author and her colleagues reported the decrease of D-neurons in the striatum and nucleus accumbens of postmortem brains of patients with schizophrenia. This may imply the decrease of trace amine synthesis, resulting the reduced stimulation of TAAR1 on terminals of midbrain VTA DA neurons, and may lead to mesolimbic DA hyperactivity in schizophrenia. The decrease of striatal D-neurons of postmortem brains of schizophrenia is supposed to be due to neural stem cell dysfunction in the subventricular zone of lateral ventricle. The decrease of striatal D-neurons and acts of TAAR1 signals on DA neurons-might explain mesolimbic DA hyperactivity of schizophrenia.
文摘Neural stem cell (NSC) hypofunction is an etiological hypothesis of schizophrenia. Although dopamine (DA) dysfunction is also a widely accepted hypothesis, molecular background of mesolimbic DA hyperactivity has not yet been well known. Here, the author proposes “D-cell hypothesis”, accounting for molecular basis of mesolimbic DA hyperactivity of schizophrenia, by NSC hypofunction and decrease of putative NSC-induced D-cells. The “D-cell” is defined as “non-monoaminergic aromatic L-amino acid decarboxylase (AADC)-containing cell”. D-cells produce trace amines, and also take up amine precursors and convert them to amines by decarboxylation. The author reported “dopa-decarboxylating neurons specific to the human striatum”, that is, “D-neurons” in the human striatum, and decrease of striatal D-neurons in patients with schizophrenia. Trace amine-associated receptor, type 1 (TAAR1), a subtype of trace amine receptors, having a quite number of ligands such as tyramine, β-phenylethylamine (PEA) and methamphetamine, has modulating functions on monoamine neurons. It has been known that reduced binding of ligands to TAAR1 receptors on DA terminal of DA neurons of the midbrain ventral tegmental area (VTA) increased firing frequency of VTA DA neurons. In brains of schizophrenia, NSC hypofunction in the subventricular zone of lateral ventricle may cause decrease of D-neurons in the striatum and nucleus accumbens, and may result in decrease of trace amine signals. Decrease of trace amine signals to TAAR1 on VTA DA neurons may increase firing frequency of VTA DA neurons, and may finally cause mesolimbic DA hyperactivity. Increased stimulation to DA D2 receptors of NSCs might suppress NSC proliferation, and may induce additional mesolimbic DA hyperactivity as well as D-cell decrease. This novel theory, “D-cell hypothesis”, possibly explains mesolimbic DA hyperactivity in pathogenesis of schizophrenia.
基金National Key Research and Development (2016YFC0800907)Project 973 (2015CB553504)+1 种基金National Natural Science Foundation of China(81573405)Beijing Nova Program(xx2014A014).
文摘OBJECTIVE Dopamine(DA)plays important roles in Pavlovian conditioning by mediating reward,learning and motivation.While the conditioning stimulation(CS) is the most important inducement for reinstatement in addiction.The present study investigated the specific role of the DA projections to nucleus accumbens(NAc) and medial prefrontal cortices(mPFC) from ventral tegmental area(VTA) in reinstatement induced by cue.METHODS(1)Optogenetic intracranial self-stimulation and reinstatement.DAT-Cre transgenic mice received an injection of adeno-associated viral vectors encoding channelrhodopsin2(ChR2) or control vector into the VTA resulting in the selective expression of these opsins in DA neurons.Then,we stimulated the VTA,NAc(core and shel) or mP FC [prelimbic cortex(PL) and infralimbic cortex(IL)] via an optical fiber.In the reinforcement test,the mice with ChR2 learned instrumental responses corresponding to the delivery of photostimulation into the VTA with multiple frequencies and during time;in the reinstatement phase,stimulation of the DA projections to NAc(core or shell) or mPFC(IL and PL) from VTA to induce reinstatement after 2 weeks of extinction of self-stimulation.(2)Reinstatement in cocaine self-administration.Virus encoding ChR2 or hM4 Di were injected into VTA of DAT-Cre transgenic mice.The mice with ChR2 and hM4 Di in DA neurons were trained to establish self-administration of cocaine.After 2 weeks of extinction,laser stimulation of the DA projections to NAc(core or shel) or mP FC(IL and PL) was conducted to induce reinstatement.After that,Clozapine was injected in NAc core to test the impacts of VTA-NAc core depression on the reinstatement induced by cue.(3) Photometry of VTA DA neurons in reinstatement.DAT-Cre transgenic mice were received an injection of AAV-DIO-Gcamp6 m into VTA.After cocaine self-administration and extinction,mice with Gcamp6 m were challenged by cue(paired with cocaine previously) and the photometry of VTA DA neurons was conducted during the reinstatement.RESULTS(1)The enhanced self-stimulation behavior was positive correlation with the stimulation of DA neurons in VTA according to the increasing frequency of stimulation and extent stimulation duration time.Furthermore,DA receptor antagonists significantly depressed the frequency curve.(2) Only stimulation of the projections to the NAc core from the VTA significantly induced reinstatement after extinction of self-stimulation,neither shell nor mPFC(PL or IL).(3) Depression of VTA-NAc core projection significantly inhibited the reinstatement induced by cue.(4) DA neurons in VTA were activated when the cue appeared during the period of reinstatement test.CONCLUSION Mesocorticolimbic DA system directly modulate the reinforcement dependant on DA receptor.The activity of DA neurons in VTA is necessary for cue induced relapse.Importantly,projections to NAc core from VTA perform the unique effects in reinstatement.
文摘BACKGROUND： Drug addiction involves two main central nervous systems, namely the dopamine and noradrenaline systems. These systems are primarily distributed in five brain regions： the ventral tegmental area, the nucleus accumbens, the prefrontal cortex, the hippocampus, and the locus coeruleus. OBJECTIVE： To investigate regional changes of guanine nucleotide binding protein-inhabitant 2 （Gi2） in dopaminergic and noradrenergic neurons in brains of morphine-tolerant and -dependent rats. DESIGN, TIME, AND SETTING： A randomized control study was performed at the Department of Neurobiology in the Second Military Medical University of Chinese PLA （Shanghai, China） between September 2002 and March 2004. MATERIALS： Thirty-six, healthy, male, Sprague-Dawley （SD） rats were used to establish morphine-dependent models. Morphine hydrochloride was a product of Shenyang First Pharmaceutical Factory （China）; naloxone hydrochloride was a product of Beijing Four-Ring Pharmaceutical Factory （China）; and α subunit of Gi2 antibody was offered by Santa Cruz Biotechnology, lnc （USA）. METHODS： Thirty-six SD rats were randomly divided into six groups （n = 6）： （1） acute morphine-dependent group, （2） acute abstinent group, （3） acute control group, （4） chronic morphine-dependent group, （5） chronic abstinent group, and （6） chronic control group. Rats in the acute morphine-dependent and the acute groups were injected with morphine （5 mg/kg）, one injection every two hours, for a total of eight injections. In the acute and chronic morphine-dependent rat models, morphine withdrawal syndrome was precipitated by an injection of naloxone （5 mg/kg）. Rats in the acute control group were given a peritoneal injection of physiological saline at the same administration time as the above two groups. Rats in the chronic morphine-dependent and chronic abstinent groups were injected with morphine three times per day. The administration dose on day 1 was initially 5 mg/kg at 20：00, which increased by 5 mg/kg at 8：00, 12：00, and 20：00 until day 7. On day 13, the dose continuously increased by 10 mg/kg until a chronic morphine-dependent rat model was successfully induced. Afterwards, the rats presented with withdrawal syndromes on naloxone （5 mg/kg） at 8：00 on the same day. Rats in the chronic control group were injected with physiological saline at the same time of the two chronic groups. MAIN OUTCOME MEASURES： The concentration of Gi2 protein in the five brain regions （ventral tegmental area, nucleus accumbens, prefrontal cortex, locus coeruleus, and hippocampus） was detected by immunohistochemistry. RESULTS： In the acute morphine-dependent and acute abstinent groups, Gi2 protein concentration was significantly decreased in the nucleus accumbens, compared to the acute control group （P 〈 0.01）, while no obvious changes were detected in other brain regions. In the chronic morphine-dependent and chronic abstinent groups, Gi2 protein concentration was significantly decreased in the nucleus accumbens, but significantly increased in the locus coeruleus （P 〈 0.01 ） compared to the chronic control group. CONCLUSION： Morphine dependence and tolerance may induce obvious reductions of Gi2 protein levels in the nucleus accumbens of rats. Chronic morphine dependence desensitizes the homologous neurons.
文摘Recent pharmacological discovery on trace amine-associated receptor, type 1(TAAR1) has emphasized importance of trace amines in pathogenesis of psychoses, such as schizophrenia. TAAR1 has many ligands, including tyramine, β-phenylethylamine (PEA), amphetamines, and 3’-iodothyronamine. So-called D-neurons are putative producer of trace amines, endogenous ligands of TAAR1. The D-neuron is defined “the aromatic L-amino acid decarboxylase (AADC)-containing neuron, but not dopaminergic nor serotonergic”, i.e. not containing tyrosine hydroxylase nor tryptophan hydroxylase. AADC is an enzyme, also called dopa decarboxylase (DDC). The localization of D-neurons in the central nervous system has been specified into 15 groups, from the spinal cord (D1) to striatum (D15). We showed the decrease of D-neurons in D15 in postmortem brains of schizophrenia, where midbrain dopamine (DA) neurons are heavily innervated. Decrease of D-neurons may cause reduction of trace amines in the striatum, and may also decrease stimulation of TAAR1 on striatal terminals of ventral tegmental area (VTA) DA neurons. This might increase firing frequency of VTA DA neurons, and causes DA hyperactivity in the striatum and nucleus accumbens. In the present article, the author introduces the novel theory, “D-cell hypothesis”, for mesolimbic DA hyperactivity of schizophrenia. Some clinical and/or experimental evidences that support this hypothesis are mentioned. The D-neuron, as a trace amine producer, is a clue for elucidating pathogenesis of psychoses, as well as human mental functions. Thus, signal transduction of D-neurons should be investigated.
基金supported by grants from the National Natural Science Foundation of China(81873787,81961128024,32170994,and 82201362)Shanghai Natural Science Foundation(18ZR1424800 and 20ZR1430000)+1 种基金a Shanghai Municipal Science and Technology Major Project(2018SHZDZX05)the innovative research team of high-level local universities in Shanghai.
文摘Itch is an unpleasant sensation that provokes the desire to scratch.While acute itch serves as a protec-tive system to warn the body of external irritating agents,chronic itch is a debilitating but poorly-treated clinical dis-ease leading to repetitive scratching and skin lesions.How-ever,the neural mechanisms underlying the pathophysiol-ogy of chronic itch remain mysterious.Here,we identified a cell type-dependent role of the anterior cingulate cortex(ACC)in controlling chronic itch-related excessive scratch-ing behaviors in mice.Moreover,we delineated a neural circuit originating from excitatory neurons of the ACC to the ventral tegmental area(VTA)that was critically involved in chronic itch.Furthermore,we demonstrate that the ACC→VTA circuit also selectively modulated histaminergic acute itch.Finally,the ACC neurons were shown to predomi-nantly innervate the non-dopaminergic neurons of the VTA.Taken together,our findings uncover a cortex-midbrain cir-cuit for chronic itch-evoked scratching behaviors and shed novel insights on therapeutic intervention.
文摘Objective To observe the effect of acupuncture stimulation of the sacral segment on the excitability of the cerebral cortex and the activity of the urinary bladder and the involvement of the cholinergic neurons in the laterodorsal tegmental （LDT） nucleus of the brainstem in acupuncture-induced electroencephalogram （EEG） changes. Methods A total of 109 SD rats were used in the present study. Under anesthesia （urethane）, a pair of stainless steel electrodes was separately implanted into the frontal and parietal bony sutures to record EEG. Glass microelectrodes were used to record extracellular discharges of single neuron of the LDT nucleus in the brainstem. Urinary bladder pressure was recorded through a catheter inserted in the bladder and the contraction was induced by infusion of normal saline. A filiform acupuncture needle was inserted into the sacral segment Ecorresponding to Zhongliao （中髎BL 33）] and rotated manually for 1 min. Results In 27 rats whose bladder was full of normal saline, acupuncture stimulation of the sacral region suppressed the contraction activity of the bladder, the fast EEG with lower amplitude and higher frequency tuned into slow EEG with higher amplitude and lower frequency in 6 cases （22.2%）. The inhibitory effect occurred from 45 s to 12 min after acupuncture manipulation. In 82 rats whose bladder was empty, acupuncture stimulation caused the fast EEG to turn into slow EEG in 71 cases （86.6%）. Simultaneously, LDT cholinergic neurons reduced their firing rates from （2.9±1.5） Hz to （1.2±0.6） Hz （n = 12, P〈0.05）, and the reduction of LDT neuronal discharge was earlier in time than the change of EEG. Conclusion Acupuncture stimulation of the sacral region can lower the excitability of the cerebral cortex and suppress bladder activity, which is closely associated with its resultant inhibitory effect on the electrical activity of LDT cholinergic neurons.
