The voltage-gated sodium channel(Na v)is widely present in mammals and can generate cell action potentials,which are related to many diseases.Theμ-Conotoxins(μ-CTx)isolated from the venom of cone snails can specific...The voltage-gated sodium channel(Na v)is widely present in mammals and can generate cell action potentials,which are related to many diseases.Theμ-Conotoxins(μ-CTx)isolated from the venom of cone snails can specifically block the voltage-gated sodium channel;it can be widely used as a necessary probe to distinguish the Na v channel subtypes.In this study,the effects of eightμ-CTx on different Na v channel isoforms were reviewed,and sequence alignment and protein homologous modeling were used to predict their biological activities,and the structure-activity relationship betweenμ-CTx and mutagenesis strategies.展开更多
OBJECTIVE Toad venom(Venenum Bufonis)isalways used for analgesia in China from ancient to modern times,but the effective component of it remains unclear.METHODS In the present study,we investigated the anti-nociceptiv...OBJECTIVE Toad venom(Venenum Bufonis)isalways used for analgesia in China from ancient to modern times,but the effective component of it remains unclear.METHODS In the present study,we investigated the anti-nociceptive effect and the underlying mechanism ofbufalin,an active ingredient fromtoad venom by animal behavior,patch clamp and calcium imaging.RESULTS Bufalin could significantly relieve formalin-induced spontaneous flinching and licking response as well as carrageenan-induced mechanical and thermal hyperalgesia.Using the whole-cel patch-clamp recording,bufalincaused remarkable suppressive effect on the peak currents of Na+channels in dorsal root ganglion neuroblastoma ND7-23 cel line in a U-shaped dependent manner.In addition,bufalinprompted the voltage-dependent activationand caused a negative shift of the fast-state inactivation of Na+channels.However,bufalin produced insignificant effect not onlyon voltage-dependent Kv4.2,Kv4.3 and BK channels,but also on the capsaicin induced Ca2+influx.CONCLUSION The present results indicate bufalin is capable of producing remarkable anti-nociceptive effects whichis probably ascribed to its specific modulation of voltage-gated Na+channels.展开更多
Voltage-gated sodium(Nav)channels are critical players in the generation and propagation of action potentials by triggering membrane depolarization.Mutations in Nav channels are associated with a variety of channelopa...Voltage-gated sodium(Nav)channels are critical players in the generation and propagation of action potentials by triggering membrane depolarization.Mutations in Nav channels are associated with a variety of channelopathies,which makes them relevant targets for pharmaceutical intervention.Sofar,the cryoelectron microscopic structure of the human Nav 1.2,Nav 1.4,and Nav 1.7 has been reported,which sheds light on the molecular basis of functional mechanism of Nav channels and provides a path toward structure-based drug discovery.In this review,we focus on the recent advances in the structure,molecular mechanism and modulation of Nav channels,and state updated sodium channel blockers for the treatment of pathophysiology disorders and briefly discuss where the blockers may be developed in the future.展开更多
Voltage-gated sodium channels(VGSCs) are transmembrane proteins responsible for generation and conduction of action potentials in excitable cells.Physiological and pharmacological studies have demonstrated that VGSCs ...Voltage-gated sodium channels(VGSCs) are transmembrane proteins responsible for generation and conduction of action potentials in excitable cells.Physiological and pharmacological studies have demonstrated that VGSCs play a critical role in chronic pain associated with tissue or nerve injury.Many long-chain peptide toxins(60-76 amino acid residues) purified from the venom of Asian scorpion Buthus martensii Karsch(BmK) are investigated to be sodium channel-specific modulators.The α-like neurotoxins that can bind to receptor site 3 of sodium channels,named as BmK I and BmK abT,could induce nociceptive effects in rats.On the contrast,the β-like neurotoxins that can bind to receptor site 4 of sodium channels,named as BmK AS,BmK AS-1 and BmK IT2,could produce potent anti-nociceptive effects in animal pain models.BmK I could strongly prolong the fast inactivation of tetrodotoxin(TTX)-sensitive Na+ currents on the rat dorsal root ganglia(DRG) neurons together with the augmentation of peak current amplitude.However,BmK IT2 and BmK ASs,potently suppressed both the peak TTX-resistant and TTX-sensitive Na+ currents on rat small DRG neurons.Moreover,BmK ASs could decrease the excitability of small DRG neurons.Thus,the nociception/anti-nociception induced by scorpion neurotoxins may attribute to their distinct modulation on sodium channels in primary afferent sensory neurons.Therefore,the sodium channel-specific modulators from BmK venom could be used as not only pharmacological tools for better understanding the roles of VGSCs in pain signal conduction,but also lead molecules in the development of ideal analgesics targeting VGSCs.展开更多
Voltage-gated sodium channels (VGSCs) play a fundamental role in controlling cellular excitability,and their abnormal activity is related to several pathological processes,including cardiac arrhythmias,epilepsy,neurod...Voltage-gated sodium channels (VGSCs) play a fundamental role in controlling cellular excitability,and their abnormal activity is related to several pathological processes,including cardiac arrhythmias,epilepsy,neurodegenerative diseases,spasticity and chronic pain.In particular,chronic visceral pain,the central symptom of functional gastrointestinal disorders such as irritable bowel syndrome,is a serious clinical problem that affects a high percentage of the world population.In spite of intense research efforts and after the dedicated decade of pain control and research,there are not many options to treat chronic pain conditions.However,there is a wealth of evidence emerging to give hope that a more refined approach may be achievable.By using electronic databases,available data on structural and functional properties of VGSCs in chronic pain,particularly functional gastrointestinal hypersensitivity,were reviewed.We summarize the involvement and molecular bases of action of VGSCs in the pathophysiology of several organic and functionalgastrointestinal disorders.We also describe the efficacy of VGSC blockers in the treatment of these neurological diseases,and outline future developments that may extend the therapeutic use of compounds that target VGSCs.Overall,clinical and experimental data indicate that isoform-specific blockers of these channels or targeting of their modulators may provide effective and novel approaches for visceral pain therapy.展开更多
Neuropathic pain has been hypothesized to be the result of aberrant expression and function of sodium channels at the site of injury. To investigate the effects of NaV1.8 antisense oligonucleotide on the expression of...Neuropathic pain has been hypothesized to be the result of aberrant expression and function of sodium channels at the site of injury. To investigate the effects of NaV1.8 antisense oligonucleotide on the expression of sodium channel mRNA in dorsal root ganglion (DRG) neurons in chronic neuropathic pain. 24 Sprague-Dawley rats weighing 200-260 g were anesthetized with the intraperitoneal injection of 300 mg·kg -1 choral hydrate. The CCI model was made by loose ligation of sciatic nerve trunk by 4-0 chromic gut. The mechanical and thermal pain threshold were measured before operation and 1, 3, 5, 7, 9, 11, 13 days after operation. A PE-10 catheter was implanted in subarachnoid space at lumbar region. On the 7th postoperative day the animals were randomly divided into 4 groups. The drugs were injected intrathecally twice a day for 5 consecutive days in group 2-4. The animals were decapitated 14 days after the surgery. The L4-L6 DRG of the operated side was removed and crushed, and total RNA was extracted with Trizol reagent. The contralateral side was used as control. The change of NaV1.8 sodium channel transcripts was determined by RT-PCR. Pain threshold was significantly lowered after CCI as compared with that in control group and was elevated 3 days after antisense oligonucleotide injection. Sensory neuron specific TTX-R sodium channel NaV1.8 transcript was down-regulated after antisense oligonucleotide injection at the dosage of 45 μg as compared with that in CCI group (P<0.01), and it was even greater at the dosage of 90 μg. The intrathecally injected NaV1.8 antisense oligonucleotide can reduce the mechanical allodynia and thermal hyperalgesia partially by downregulating the SNS transcript expression.展开更多
BACKGROUND:Some experiments have demonstrated that injecting orphanin FQ (OFQ) into lateral ventricle, which can obviously decrease the pain threshold. It is indicated that OFQ is an anti-opiate substance. However, wh...BACKGROUND:Some experiments have demonstrated that injecting orphanin FQ (OFQ) into lateral ventricle, which can obviously decrease the pain threshold. It is indicated that OFQ is an anti-opiate substance. However, whether OFQ has effects on sensory neuron ion channel in cerebral cortex needs to be further studied. OBJECTIVE:To investigate the effects of OFQ, morphine or their combination on sodium channel current of somatosensory neurons in rat cerebral cortex. DESIGN:Repeated measurement trial. SETTING:Department of Physiology, Harbin Medical University. MATERIALS:Fifty healthy Wistar rats, aged 12-16 days, of either gender, were provided by the Experimental Animal Center, Second Hospital Affiliated to Harbin Medical University. OFQ was purchased from Sigma-Aldrich Company, and morphine was provided by the Shenyang First Pharmaceutical Factory. PC2C patch clamp amplifier and LabmasterTL1were purchased from Yibo Life Science Instrument Co.,Ltd. of Huazhong University of Science and Techgnology. METHODS:This experiment was carried out in the Department of Physiology (provincial laboratory), Harbin Medical University between January 2005 and May 2006. Cortical neurons were acutely isolated from rats, and prepared into cell suspension following culture. ①Sodium channel current of somatosensory neurons in rat cerebral cortex was recorded before and after administration by whole-cell Patch clamp technique after 50 nmol/L OFQ being added to extracellular fluid. ②The amplitude of sodium channel current of somatosensory neurons in rat cerebral cortex was recorded before and after administration by the same method after 20 μmol/L morphine being added to extracellular fluid, and then the change of sodium channel current was recorded after 50 nmol/L OFQ being added. MAIN OUTCOME MEASURES:The amplitude of sodium channel current of somatosensory neurons in rat cerebral cortex following the administration of OFQ, morphine separately or their combination.. RESULTS:①The amplitude of sodium channel current of somatosensory neurons in rat cerebral cortex was significantly lower after administration of 50 nmol/L OFQ than before at the clampe of the voltage of -30 mV (P < 0.05). ②The amplitude of sodium channel current of somatosensory neurons in rat cerebral cortex was significantly lower after administration of 20 μmol/L morphine than before at the clampe of the voltage of -30 mV (P < 0.05). The sodium channel current recovered to -(2 345.24±174.18)pA after 50 nmol/L OFQ was administrated. There were significant differences in the amplitude of Na+ channel current between two interventions (P < 0.05). CONCLUSION:Morphine and OFQ can respectively reduce the amplitude of sodium channel current of somatosensory neurons in rat cerebral cortex, and OFQ can reverse the effect of morphine partly. It is indicated that OFQ can produce antiopioid activity in the central nervous system by influencing sodium channel current.展开更多
The strain of fenvalerate-resistant cotton aphids was selected using fenvalerate insecticide in the laboratory, the resistance factor of the strain was 199.54. Three degenerate primers were designed and used to perfor...The strain of fenvalerate-resistant cotton aphids was selected using fenvalerate insecticide in the laboratory, the resistance factor of the strain was 199.54. Three degenerate primers were designed and used to perform PCR amplification. A cDNA encoding partial sodium channel gene was cloned from the fenvalerate-resistant and -susceptible strains. There were two nucleotide acid differences between fenvalerate-resistant strain and -susceptible strain, resulting in an amino acid mutation, Met→Leu. It is predicted that the mutation is related to the cotton aphid resistance to fenvalerate.展开更多
Objective. To investigate the properties of voltage-gated sodium (Na+) channels in developing auditoryneurons during early postnatal stages in the mammalian central nervous system.Methods. Using the whole-cell voltage...Objective. To investigate the properties of voltage-gated sodium (Na+) channels in developing auditoryneurons during early postnatal stages in the mammalian central nervous system.Methods. Using the whole-cell voltage-clamp technique, we have studied changes in the electrophysi-ological properties of Na+ channels in the principal neurons of the medial nucleus of the trapezoid body (MNTB).Results. We found that MNTB neurons already express functional Na+ channels at postnatal day 1 (P1),and that channel density begins to increase at P5 when the neurons receive synaptic innervation andreach its maximum (～3 fold) at P11 when functional hearing onsets. These changes were paralleled byan age-dependent acceleration in both inactivation and recovery from inactivation. In contrast, there wasvery little alteration in the voltage-dependence of inactivation.Conclusion. These profound changes in the properties of voltage-gated Na+ channels may increase theexcitability of MNTB neurons and enhance their phase-locking fidelity and capacity during high-frequencysynaptic transmission.展开更多
Objective: To explore the pathogenesis of trigeminal neuralgia (TN) and to provide a new target for the drug treatment of TN by studying the expression of tetrodotoxin-resistant hNavl. 8 sodium channel protein in affe...Objective: To explore the pathogenesis of trigeminal neuralgia (TN) and to provide a new target for the drug treatment of TN by studying the expression of tetrodotoxin-resistant hNavl. 8 sodium channel protein in affected nerves of patients with TN. Methods: Twelve affected inferior alveolar nerves were obtained from patients with idiopathic TN, to whom the drug therapy was not effective. As negative control, one normal inferior alveolar nerve was obtained from patients who accepted the combined radical neck dissection with glossectomy and mandibulectomy. One muscle sample was obtained as normal control. One dorsal root ganglion from rat was as positive control. These tissues and prepared hNav1.8 antibody were conducted immunohistochemistry response. Results: hNavl. 8 channel protein was expresses in all the 12 specimens of the affected nerves of patients with TN, but not in the muscle sample and the normal inferior alveolar nerve. Conclusion:The abnormal expression of hNavl. 8 channel protein in the affected nerves of patients with TN may play an impo^nt role in the pathogenesis of TN.展开更多
Dravet syndrome is a rare epileptic encephalopathy characterized by frequent seizures beginning in the first year of life and behavioral disorders. Mutations in the sodium channel α1 subunit gene are the main cause o...Dravet syndrome is a rare epileptic encephalopathy characterized by frequent seizures beginning in the first year of life and behavioral disorders. Mutations in the sodium channel α1 subunit gene are the main cause of this disease. We report two patients with refractory seizures and psychomotor retardation in whom the final diagnosis was Dravet syndrome with confirmed mutations in the sodium channel α1 subunit gene. The mutation identified in the second patient was a novel frame shift mutation, which resulted from the deletion of five nucleotides in exon 24.展开更多
Epilepsy is described as the most common chronic brain disorder. A typical symptom of epilepsy results in uncontrolled convulsions caused by temporary excessive neuronal discharges. Although several new anticon-vulsan...Epilepsy is described as the most common chronic brain disorder. A typical symptom of epilepsy results in uncontrolled convulsions caused by temporary excessive neuronal discharges. Although several new anticon-vulsants have been introduced, some types of seizures have still not been adequately controlled with these new and current therapies. There is an urgent need to develop new anticonvulsant drugs to control the many different types of seizures. Many studies have shown that the epilepsies involve more than one mechanism and therefore may be responsible for the various types of observed seizures. Recently reported studies have shown that a group of newly synthesized 6 Hz active anticonvulsant fluorinated N-benzamide enaminones exhibited selective inhibitions of voltage-gated sodium (Nav) channels. Nav channels are responsible for the initial inward currents during the depolarization phases of the action potential in excitable cells. The activation and opening of Nav channels result in the initial phases of action potentials. We hypothesize that there is an essential pharmacophore model for the interactions between these enaminones and the active sites of Nav channels. The research reported here is focused on molecular docking studies of the interactions that occur between the fluorinated N-benzamide enaminones and the Nav channels. These studies may open an avenue for designing anticonvulsant drugs by inhibiting Nav channels.展开更多
Two point mutations(F1845Y and V1848I)in the voltage-gated sodium channel gene of Plutella xylostella are involved in the target-site resistance to sodium channel blocker insecticides(SCBIs).The contribution of the in...Two point mutations(F1845Y and V1848I)in the voltage-gated sodium channel gene of Plutella xylostella are involved in the target-site resistance to sodium channel blocker insecticides(SCBIs).The contribution of the individual mutations to the SCBI resistance and the associated inheritance modes is as yet unclear.Through 2 rounds of single-pair crossing and marker-assisted selection,2 P xylostella strains(1845Y and 18481)bearing homozygous F1845Y or V18481 mutant alleles were successfully established from a field-collected population,and the contribution of each mutation to SCBI resistance,as well as associated inheritance patterns,was determined.When compared with the susceptible SZPS strain,each of the mutations individually conferred equally high-level resistance to indoxacarb(378 and 313 fold)and metaflumizone(734 and 674 fold),respectively.However,dominance levels of resistance to SCBIs were significantly different between the 2 resistant strains.Resistance of the 1845Y strain to indoxacarb and metaflumizone was inherited as an autosomal and incompletely dominant trait(D values ranged from 0.43 to 0.76).In contrast,that of the 1848I strain followed an autosomal but incompletely recessive to semidominant mode(D values:-0.24 to 0.09).Our findings enriched the current understanding of inheritance and mechanisms of SCBI resistance in P.xylostella,and will help develop resistance management programs for P:xylostella and othereconomic pests.展开更多
Epilepsy is a neurological disease characterized by excessive and abnormal hyper-synchrony of electrical discharges of the brain and a predisposition to generate epileptic seizures resulting in a broad spectrum of neu...Epilepsy is a neurological disease characterized by excessive and abnormal hyper-synchrony of electrical discharges of the brain and a predisposition to generate epileptic seizures resulting in a broad spectrum of neurobiological insults,imposing psychological,cognitive,social and also economic burdens to the sufferer.Voltage-gated sodium channels(VGSCs)are essential for the generation and propagation of action potentials throughout the central nervous system.Dysfunction of these channels has been implicated in the pathogenesis of epilepsy.VGSC inhibitors have been demonstrated to act as anticonvulsants to suppress the abnormal neuronal firing underlying epileptic seizures,and are used for the management and treatment of both genetic-idiopathic and acquired epilepsies.We discuss the forms of idiopathic and acquired epilepsies caused by VGSC mutations and the therapeutic efficacy of VGSC blockers in idiopathic,acquired and pharmacoresistant forms of epilepsy in this review.We conclude that there is a need for better alternative therapies that can be used alone or in combination with VGSC inhibitors in the management of epilepsies.The current anti-seizure medications(ASMs)especially for pharmacoresistant epilepsies and some other types of epilepsy have not yielded expected therapeutic efficacy partly because they do not show subtype-selectivity in blocking sodium channels while also bringing side effects.Therefore,there is a need to develop novel drug cocktails with enhanced selectivity for specific VGSC isoforms,to achieve better treatment of pharmacoresistant epilepsies and other types of epileptic seizures.展开更多
Diverse subtypes of voltage-gated sodium channels(VGSCs)have been found throughout tissues of the brain,muscles and the heart.Neurotoxins extracted from the venom of the Asian scorpion Buthus martensi Karsch(BmK)act a...Diverse subtypes of voltage-gated sodium channels(VGSCs)have been found throughout tissues of the brain,muscles and the heart.Neurotoxins extracted from the venom of the Asian scorpion Buthus martensi Karsch(BmK)act as sodium channel-specific modulators and have therefore been widely used to study VGSCs.α-type neurotoxins,named BmK I,BmKαIV and BmK abT,bind to receptor site-3 on VGSCs and can strongly prolong the inactivation phase of VGSCs.In contrast,β-type neurotoxins,named BmK AS,BmK AS-1,BmK IT and BmK IT2,occupy receptor site-4 on VGSCs and can suppress peak currents and hyperpolarize the activation kinetics of sodium channels.Accumulating evidence from binding assays of scorpion neurotoxins on VGSCs,however,indicate that pharmacological sensitivity of VGSC subtypes to different modulators is much more complex than that suggested by the simpleα-type and β-type neurotoxin distinction.Exploring the mechanisms of possible dynamic interactions between site 3-/4-specific modulators and region-and/or speciesspecific subtypes of VGSCs would therefore greatly expand our understanding of the physiological and pharmacological properties of diverse VGSCs.In this review,we discuss the pharmacological and structural diversity of VGSCs as revealed by studies exploring the binding properties and cross-competitive binding of site 3-or site 4-specific modulators in VGSC subtypes in synaptosomes from distinct tissues of diverse species.展开更多
The present study was designed to search for compounds with analgesic activity from the Schizophyllum commune(SC), which is widely consumed as edible and medicinal mushroom world. Thin layer chromatography(TLC), tosil...The present study was designed to search for compounds with analgesic activity from the Schizophyllum commune(SC), which is widely consumed as edible and medicinal mushroom world. Thin layer chromatography(TLC), tosilica gel column chromatography, sephadex LH 20, and reverse-phase high performance liquid chromatography(RP-HPLC) were used to isolate and purify compounds from SC. Structural analysis of the isolated compounds was based on nuclear magnetic resonance(NMR). The effects of these compounds on voltage-gated sodium(NaV) channels were evaluated using patch clamp. The analgesic activity of these compounds was tested in two types of mouse pain models induced by noxious chemicals. Five phenolic acids identified from SC extracts in the present study included vanillic acid, m-hydroxybenzoic acid, o-hydroxybenzeneacetic acid, 3-hydroxy-5-methybenzoic acid, and p-hydroxybenzoic acid. They inhibited the activity of both tetrodotoxin-resistant(TTX-r) and tetrodotoxin-sensitive(TTX-s) NaV channels. All the compounds showed low selectivity on NaV channel subtypes. After intraperitoneal injection, three compounds of these compounds exerted analgesic activity in mice. In conclusion, phenolic acids identified in SC demonstrated analgesic activity, facilitating the mechanistic studies of SC in the treatment of neurasthenia.展开更多
Growth differentiation factor 15(GDF-15)is a member of the transforming growth factor-βsuperfamily.It is widely distributed in the central and peripheral nervous systems.Whether and how GDF-15 modulates nociceptive s...Growth differentiation factor 15(GDF-15)is a member of the transforming growth factor-βsuperfamily.It is widely distributed in the central and peripheral nervous systems.Whether and how GDF-15 modulates nociceptive signaling remains unclear.Behaviorally,we found that peripheral GDF-15 significantly elevated nociceptive response thresholds to mechanical and thermal stimuli in naïve and arthritic rats.Electrophysiologically,we demonstrated that GDF-15 decreased the excitability of small-diameter dorsal root ganglia(DRG)neurons.Furthermore,GDF-15 concentration-dependently suppressed tetrodotoxin-resistant sodium channel Nav1.8 currents,and shifted the steady-state inactivation curves of Nav1.8 in a hyperpolarizing direction.GDF-15 also reduced window currents and slowed down the recovery rate of Nav1.8 channels,suggesting that GDF-15 accelerated inactivation and slowed recovery of the channel.Immunohistochemistry results showed that activin receptor-like kinase-2(ALK2)was widely expressed in DRG medium-and small-diameter neurons,and some of them were Nav1.8-positive.Blockade of ALK2 prevented the GDF-15-induced inhibition of Nav1.8 currents and nociceptive behaviors.Inhibition of PKA and ERK,but not PKC,blocked the inhibitory effect of GDF-15 on Nav1.8 currents.These results suggest a functional link between GDF-15 and Nav1.8 in DRG neurons via ALK2 receptors and PKA associated with MEK/ERK,which mediate the peripheral analgesia of GDF-15.展开更多
Objective To observe the effects of glutamate on sodium channel in acutely dissociated hippocampal CA1 pyramidal neurons of rats.Methods Voltage-dependent sodium currents (INa) in acutely dissociated hippocampal CA1 p...Objective To observe the effects of glutamate on sodium channel in acutely dissociated hippocampal CA1 pyramidal neurons of rats.Methods Voltage-dependent sodium currents (INa) in acutely dissociated hippocampal CA1 pyramidal neurons of neonate rats were recorded by whole-cell patchclamp of the brain slice technique when a series of doses of glutamate (100-1000μmol/L) were applied.Results Different concentrations of glutamate could inhibit INa,and higher concentration of glutamate affected greater inhibition.In same concentration on INa at different times,longer time glutamate affected greater inhibition.And glutamate could significantly shift activation curve of INa to the right and make inactivation curve of INa negative drift.Conclusion Glutamate can inhibit voltage-dependent sodium channel.Its blockage on INa has voltage-dependent,time-dependent,and dose-dependent characteristics.展开更多
基金Supported by Special Scientific Research Project of the Hainan Academician Innovation Platform,China(YSPTZX202132)Hainan Provincial Natural Science Foundation,China(820RC636)Hainan Provincial Key Point Research and Invention Program,China(ZDYF2022SHFZ309).
文摘The voltage-gated sodium channel(Na v)is widely present in mammals and can generate cell action potentials,which are related to many diseases.Theμ-Conotoxins(μ-CTx)isolated from the venom of cone snails can specifically block the voltage-gated sodium channel;it can be widely used as a necessary probe to distinguish the Na v channel subtypes.In this study,the effects of eightμ-CTx on different Na v channel isoforms were reviewed,and sequence alignment and protein homologous modeling were used to predict their biological activities,and the structure-activity relationship betweenμ-CTx and mutagenesis strategies.
基金The project supported by Innovation Program of Shanghai Municipal Education Commission(15ZZ063)by Research Project of Putuo Hospital,Shanghai University of Traditional Chinese Medicine(2014YJ002)
文摘OBJECTIVE Toad venom(Venenum Bufonis)isalways used for analgesia in China from ancient to modern times,but the effective component of it remains unclear.METHODS In the present study,we investigated the anti-nociceptive effect and the underlying mechanism ofbufalin,an active ingredient fromtoad venom by animal behavior,patch clamp and calcium imaging.RESULTS Bufalin could significantly relieve formalin-induced spontaneous flinching and licking response as well as carrageenan-induced mechanical and thermal hyperalgesia.Using the whole-cel patch-clamp recording,bufalincaused remarkable suppressive effect on the peak currents of Na+channels in dorsal root ganglion neuroblastoma ND7-23 cel line in a U-shaped dependent manner.In addition,bufalinprompted the voltage-dependent activationand caused a negative shift of the fast-state inactivation of Na+channels.However,bufalin produced insignificant effect not onlyon voltage-dependent Kv4.2,Kv4.3 and BK channels,but also on the capsaicin induced Ca2+influx.CONCLUSION The present results indicate bufalin is capable of producing remarkable anti-nociceptive effects whichis probably ascribed to its specific modulation of voltage-gated Na+channels.
基金the National Natural Science Foundation of China(Nos.81473254,81773637,81773594,U1703111)the Fundamental Research Fund for the Central Universities(No.2017KFYXJJ151).
文摘Voltage-gated sodium(Nav)channels are critical players in the generation and propagation of action potentials by triggering membrane depolarization.Mutations in Nav channels are associated with a variety of channelopathies,which makes them relevant targets for pharmaceutical intervention.Sofar,the cryoelectron microscopic structure of the human Nav 1.2,Nav 1.4,and Nav 1.7 has been reported,which sheds light on the molecular basis of functional mechanism of Nav channels and provides a path toward structure-based drug discovery.In this review,we focus on the recent advances in the structure,molecular mechanism and modulation of Nav channels,and state updated sodium channel blockers for the treatment of pathophysiology disorders and briefly discuss where the blockers may be developed in the future.
基金grants from National Basic Research Development Program of China(No.2006CB500801)National Natural Sciences Foundation of China(No.30370446)
文摘Voltage-gated sodium channels(VGSCs) are transmembrane proteins responsible for generation and conduction of action potentials in excitable cells.Physiological and pharmacological studies have demonstrated that VGSCs play a critical role in chronic pain associated with tissue or nerve injury.Many long-chain peptide toxins(60-76 amino acid residues) purified from the venom of Asian scorpion Buthus martensii Karsch(BmK) are investigated to be sodium channel-specific modulators.The α-like neurotoxins that can bind to receptor site 3 of sodium channels,named as BmK I and BmK abT,could induce nociceptive effects in rats.On the contrast,the β-like neurotoxins that can bind to receptor site 4 of sodium channels,named as BmK AS,BmK AS-1 and BmK IT2,could produce potent anti-nociceptive effects in animal pain models.BmK I could strongly prolong the fast inactivation of tetrodotoxin(TTX)-sensitive Na+ currents on the rat dorsal root ganglia(DRG) neurons together with the augmentation of peak current amplitude.However,BmK IT2 and BmK ASs,potently suppressed both the peak TTX-resistant and TTX-sensitive Na+ currents on rat small DRG neurons.Moreover,BmK ASs could decrease the excitability of small DRG neurons.Thus,the nociception/anti-nociception induced by scorpion neurotoxins may attribute to their distinct modulation on sodium channels in primary afferent sensory neurons.Therefore,the sodium channel-specific modulators from BmK venom could be used as not only pharmacological tools for better understanding the roles of VGSCs in pain signal conduction,but also lead molecules in the development of ideal analgesics targeting VGSCs.
文摘Voltage-gated sodium channels (VGSCs) play a fundamental role in controlling cellular excitability,and their abnormal activity is related to several pathological processes,including cardiac arrhythmias,epilepsy,neurodegenerative diseases,spasticity and chronic pain.In particular,chronic visceral pain,the central symptom of functional gastrointestinal disorders such as irritable bowel syndrome,is a serious clinical problem that affects a high percentage of the world population.In spite of intense research efforts and after the dedicated decade of pain control and research,there are not many options to treat chronic pain conditions.However,there is a wealth of evidence emerging to give hope that a more refined approach may be achievable.By using electronic databases,available data on structural and functional properties of VGSCs in chronic pain,particularly functional gastrointestinal hypersensitivity,were reviewed.We summarize the involvement and molecular bases of action of VGSCs in the pathophysiology of several organic and functionalgastrointestinal disorders.We also describe the efficacy of VGSC blockers in the treatment of these neurological diseases,and outline future developments that may extend the therapeutic use of compounds that target VGSCs.Overall,clinical and experimental data indicate that isoform-specific blockers of these channels or targeting of their modulators may provide effective and novel approaches for visceral pain therapy.
文摘Neuropathic pain has been hypothesized to be the result of aberrant expression and function of sodium channels at the site of injury. To investigate the effects of NaV1.8 antisense oligonucleotide on the expression of sodium channel mRNA in dorsal root ganglion (DRG) neurons in chronic neuropathic pain. 24 Sprague-Dawley rats weighing 200-260 g were anesthetized with the intraperitoneal injection of 300 mg·kg -1 choral hydrate. The CCI model was made by loose ligation of sciatic nerve trunk by 4-0 chromic gut. The mechanical and thermal pain threshold were measured before operation and 1, 3, 5, 7, 9, 11, 13 days after operation. A PE-10 catheter was implanted in subarachnoid space at lumbar region. On the 7th postoperative day the animals were randomly divided into 4 groups. The drugs were injected intrathecally twice a day for 5 consecutive days in group 2-4. The animals were decapitated 14 days after the surgery. The L4-L6 DRG of the operated side was removed and crushed, and total RNA was extracted with Trizol reagent. The contralateral side was used as control. The change of NaV1.8 sodium channel transcripts was determined by RT-PCR. Pain threshold was significantly lowered after CCI as compared with that in control group and was elevated 3 days after antisense oligonucleotide injection. Sensory neuron specific TTX-R sodium channel NaV1.8 transcript was down-regulated after antisense oligonucleotide injection at the dosage of 45 μg as compared with that in CCI group (P<0.01), and it was even greater at the dosage of 90 μg. The intrathecally injected NaV1.8 antisense oligonucleotide can reduce the mechanical allodynia and thermal hyperalgesia partially by downregulating the SNS transcript expression.
基金Department of Health of Heilongjiang Province, No. 2003-097Youth Science Foundation of Medical Basic Subjects of Harbin Medical University,No. 060035
文摘BACKGROUND:Some experiments have demonstrated that injecting orphanin FQ (OFQ) into lateral ventricle, which can obviously decrease the pain threshold. It is indicated that OFQ is an anti-opiate substance. However, whether OFQ has effects on sensory neuron ion channel in cerebral cortex needs to be further studied. OBJECTIVE:To investigate the effects of OFQ, morphine or their combination on sodium channel current of somatosensory neurons in rat cerebral cortex. DESIGN:Repeated measurement trial. SETTING:Department of Physiology, Harbin Medical University. MATERIALS:Fifty healthy Wistar rats, aged 12-16 days, of either gender, were provided by the Experimental Animal Center, Second Hospital Affiliated to Harbin Medical University. OFQ was purchased from Sigma-Aldrich Company, and morphine was provided by the Shenyang First Pharmaceutical Factory. PC2C patch clamp amplifier and LabmasterTL1were purchased from Yibo Life Science Instrument Co.,Ltd. of Huazhong University of Science and Techgnology. METHODS:This experiment was carried out in the Department of Physiology (provincial laboratory), Harbin Medical University between January 2005 and May 2006. Cortical neurons were acutely isolated from rats, and prepared into cell suspension following culture. ①Sodium channel current of somatosensory neurons in rat cerebral cortex was recorded before and after administration by whole-cell Patch clamp technique after 50 nmol/L OFQ being added to extracellular fluid. ②The amplitude of sodium channel current of somatosensory neurons in rat cerebral cortex was recorded before and after administration by the same method after 20 μmol/L morphine being added to extracellular fluid, and then the change of sodium channel current was recorded after 50 nmol/L OFQ being added. MAIN OUTCOME MEASURES:The amplitude of sodium channel current of somatosensory neurons in rat cerebral cortex following the administration of OFQ, morphine separately or their combination.. RESULTS:①The amplitude of sodium channel current of somatosensory neurons in rat cerebral cortex was significantly lower after administration of 50 nmol/L OFQ than before at the clampe of the voltage of -30 mV (P < 0.05). ②The amplitude of sodium channel current of somatosensory neurons in rat cerebral cortex was significantly lower after administration of 20 μmol/L morphine than before at the clampe of the voltage of -30 mV (P < 0.05). The sodium channel current recovered to -(2 345.24±174.18)pA after 50 nmol/L OFQ was administrated. There were significant differences in the amplitude of Na+ channel current between two interventions (P < 0.05). CONCLUSION:Morphine and OFQ can respectively reduce the amplitude of sodium channel current of somatosensory neurons in rat cerebral cortex, and OFQ can reverse the effect of morphine partly. It is indicated that OFQ can produce antiopioid activity in the central nervous system by influencing sodium channel current.
基金supported by the National 973 Program(G2000016207)National 863 Program,China(2001AA249041).
文摘The strain of fenvalerate-resistant cotton aphids was selected using fenvalerate insecticide in the laboratory, the resistance factor of the strain was 199.54. Three degenerate primers were designed and used to perform PCR amplification. A cDNA encoding partial sodium channel gene was cloned from the fenvalerate-resistant and -susceptible strains. There were two nucleotide acid differences between fenvalerate-resistant strain and -susceptible strain, resulting in an amino acid mutation, Met→Leu. It is predicted that the mutation is related to the cotton aphid resistance to fenvalerate.
基金This work was supported by an operaing grant and a scholarship from the Medical Research Council of Canada(MRC)and by a start-up fund from the Hospital for Sick Children Research Institute to L,Y.W.
文摘Objective. To investigate the properties of voltage-gated sodium (Na+) channels in developing auditoryneurons during early postnatal stages in the mammalian central nervous system.Methods. Using the whole-cell voltage-clamp technique, we have studied changes in the electrophysi-ological properties of Na+ channels in the principal neurons of the medial nucleus of the trapezoid body (MNTB).Results. We found that MNTB neurons already express functional Na+ channels at postnatal day 1 (P1),and that channel density begins to increase at P5 when the neurons receive synaptic innervation andreach its maximum (～3 fold) at P11 when functional hearing onsets. These changes were paralleled byan age-dependent acceleration in both inactivation and recovery from inactivation. In contrast, there wasvery little alteration in the voltage-dependence of inactivation.Conclusion. These profound changes in the properties of voltage-gated Na+ channels may increase theexcitability of MNTB neurons and enhance their phase-locking fidelity and capacity during high-frequencysynaptic transmission.
文摘Objective: To explore the pathogenesis of trigeminal neuralgia (TN) and to provide a new target for the drug treatment of TN by studying the expression of tetrodotoxin-resistant hNavl. 8 sodium channel protein in affected nerves of patients with TN. Methods: Twelve affected inferior alveolar nerves were obtained from patients with idiopathic TN, to whom the drug therapy was not effective. As negative control, one normal inferior alveolar nerve was obtained from patients who accepted the combined radical neck dissection with glossectomy and mandibulectomy. One muscle sample was obtained as normal control. One dorsal root ganglion from rat was as positive control. These tissues and prepared hNav1.8 antibody were conducted immunohistochemistry response. Results: hNavl. 8 channel protein was expresses in all the 12 specimens of the affected nerves of patients with TN, but not in the muscle sample and the normal inferior alveolar nerve. Conclusion:The abnormal expression of hNavl. 8 channel protein in the affected nerves of patients with TN may play an impo^nt role in the pathogenesis of TN.
文摘Dravet syndrome is a rare epileptic encephalopathy characterized by frequent seizures beginning in the first year of life and behavioral disorders. Mutations in the sodium channel α1 subunit gene are the main cause of this disease. We report two patients with refractory seizures and psychomotor retardation in whom the final diagnosis was Dravet syndrome with confirmed mutations in the sodium channel α1 subunit gene. The mutation identified in the second patient was a novel frame shift mutation, which resulted from the deletion of five nucleotides in exon 24.
文摘Epilepsy is described as the most common chronic brain disorder. A typical symptom of epilepsy results in uncontrolled convulsions caused by temporary excessive neuronal discharges. Although several new anticon-vulsants have been introduced, some types of seizures have still not been adequately controlled with these new and current therapies. There is an urgent need to develop new anticonvulsant drugs to control the many different types of seizures. Many studies have shown that the epilepsies involve more than one mechanism and therefore may be responsible for the various types of observed seizures. Recently reported studies have shown that a group of newly synthesized 6 Hz active anticonvulsant fluorinated N-benzamide enaminones exhibited selective inhibitions of voltage-gated sodium (Nav) channels. Nav channels are responsible for the initial inward currents during the depolarization phases of the action potential in excitable cells. The activation and opening of Nav channels result in the initial phases of action potentials. We hypothesize that there is an essential pharmacophore model for the interactions between these enaminones and the active sites of Nav channels. The research reported here is focused on molecular docking studies of the interactions that occur between the fluorinated N-benzamide enaminones and the Nav channels. These studies may open an avenue for designing anticonvulsant drugs by inhibiting Nav channels.
基金supported by grants from National Natural Science Foundation of China(No.32072454)the Sanya Institute of Nanjing Agricultural University(No.NAUSY-MSO9).
文摘Two point mutations(F1845Y and V1848I)in the voltage-gated sodium channel gene of Plutella xylostella are involved in the target-site resistance to sodium channel blocker insecticides(SCBIs).The contribution of the individual mutations to the SCBI resistance and the associated inheritance modes is as yet unclear.Through 2 rounds of single-pair crossing and marker-assisted selection,2 P xylostella strains(1845Y and 18481)bearing homozygous F1845Y or V18481 mutant alleles were successfully established from a field-collected population,and the contribution of each mutation to SCBI resistance,as well as associated inheritance patterns,was determined.When compared with the susceptible SZPS strain,each of the mutations individually conferred equally high-level resistance to indoxacarb(378 and 313 fold)and metaflumizone(734 and 674 fold),respectively.However,dominance levels of resistance to SCBIs were significantly different between the 2 resistant strains.Resistance of the 1845Y strain to indoxacarb and metaflumizone was inherited as an autosomal and incompletely dominant trait(D values ranged from 0.43 to 0.76).In contrast,that of the 1848I strain followed an autosomal but incompletely recessive to semidominant mode(D values:-0.24 to 0.09).Our findings enriched the current understanding of inheritance and mechanisms of SCBI resistance in P.xylostella,and will help develop resistance management programs for P:xylostella and othereconomic pests.
文摘Epilepsy is a neurological disease characterized by excessive and abnormal hyper-synchrony of electrical discharges of the brain and a predisposition to generate epileptic seizures resulting in a broad spectrum of neurobiological insults,imposing psychological,cognitive,social and also economic burdens to the sufferer.Voltage-gated sodium channels(VGSCs)are essential for the generation and propagation of action potentials throughout the central nervous system.Dysfunction of these channels has been implicated in the pathogenesis of epilepsy.VGSC inhibitors have been demonstrated to act as anticonvulsants to suppress the abnormal neuronal firing underlying epileptic seizures,and are used for the management and treatment of both genetic-idiopathic and acquired epilepsies.We discuss the forms of idiopathic and acquired epilepsies caused by VGSC mutations and the therapeutic efficacy of VGSC blockers in idiopathic,acquired and pharmacoresistant forms of epilepsy in this review.We conclude that there is a need for better alternative therapies that can be used alone or in combination with VGSC inhibitors in the management of epilepsies.The current anti-seizure medications(ASMs)especially for pharmacoresistant epilepsies and some other types of epilepsy have not yielded expected therapeutic efficacy partly because they do not show subtype-selectivity in blocking sodium channels while also bringing side effects.Therefore,there is a need to develop novel drug cocktails with enhanced selectivity for specific VGSC isoforms,to achieve better treatment of pharmacoresistant epilepsies and other types of epileptic seizures.
基金supported by the National Basic Research Program of China(Grant Nos.1999054001,2006CB500801,and 2010CB529806)partially by grants from Key discipline“Molecular Physiology”of Shanghai Education Committee.
文摘Diverse subtypes of voltage-gated sodium channels(VGSCs)have been found throughout tissues of the brain,muscles and the heart.Neurotoxins extracted from the venom of the Asian scorpion Buthus martensi Karsch(BmK)act as sodium channel-specific modulators and have therefore been widely used to study VGSCs.α-type neurotoxins,named BmK I,BmKαIV and BmK abT,bind to receptor site-3 on VGSCs and can strongly prolong the inactivation phase of VGSCs.In contrast,β-type neurotoxins,named BmK AS,BmK AS-1,BmK IT and BmK IT2,occupy receptor site-4 on VGSCs and can suppress peak currents and hyperpolarize the activation kinetics of sodium channels.Accumulating evidence from binding assays of scorpion neurotoxins on VGSCs,however,indicate that pharmacological sensitivity of VGSC subtypes to different modulators is much more complex than that suggested by the simpleα-type and β-type neurotoxin distinction.Exploring the mechanisms of possible dynamic interactions between site 3-/4-specific modulators and region-and/or speciesspecific subtypes of VGSCs would therefore greatly expand our understanding of the physiological and pharmacological properties of diverse VGSCs.In this review,we discuss the pharmacological and structural diversity of VGSCs as revealed by studies exploring the binding properties and cross-competitive binding of site 3-or site 4-specific modulators in VGSC subtypes in synaptosomes from distinct tissues of diverse species.
基金partly supported by Ministry of Science and Technology of China(No.2013CB911300)National Natural Science Foundation of China(Nos.81225024,31025025,31260208,and U1132601)
文摘The present study was designed to search for compounds with analgesic activity from the Schizophyllum commune(SC), which is widely consumed as edible and medicinal mushroom world. Thin layer chromatography(TLC), tosilica gel column chromatography, sephadex LH 20, and reverse-phase high performance liquid chromatography(RP-HPLC) were used to isolate and purify compounds from SC. Structural analysis of the isolated compounds was based on nuclear magnetic resonance(NMR). The effects of these compounds on voltage-gated sodium(NaV) channels were evaluated using patch clamp. The analgesic activity of these compounds was tested in two types of mouse pain models induced by noxious chemicals. Five phenolic acids identified from SC extracts in the present study included vanillic acid, m-hydroxybenzoic acid, o-hydroxybenzeneacetic acid, 3-hydroxy-5-methybenzoic acid, and p-hydroxybenzoic acid. They inhibited the activity of both tetrodotoxin-resistant(TTX-r) and tetrodotoxin-sensitive(TTX-s) NaV channels. All the compounds showed low selectivity on NaV channel subtypes. After intraperitoneal injection, three compounds of these compounds exerted analgesic activity in mice. In conclusion, phenolic acids identified in SC demonstrated analgesic activity, facilitating the mechanistic studies of SC in the treatment of neurasthenia.
基金This work was supported by the National Natural Science Foundation of China(82021002,31771164,and 31930042)the National Key R&D Program of China(2017YFB0403803)+1 种基金the Innovative Research Team of High-level Local Universities in Shanghai,Shanghai Municipal Science and Technology Major Project(2018SHZDZX01)Zhang Jiang Laboratory.
文摘Growth differentiation factor 15(GDF-15)is a member of the transforming growth factor-βsuperfamily.It is widely distributed in the central and peripheral nervous systems.Whether and how GDF-15 modulates nociceptive signaling remains unclear.Behaviorally,we found that peripheral GDF-15 significantly elevated nociceptive response thresholds to mechanical and thermal stimuli in naïve and arthritic rats.Electrophysiologically,we demonstrated that GDF-15 decreased the excitability of small-diameter dorsal root ganglia(DRG)neurons.Furthermore,GDF-15 concentration-dependently suppressed tetrodotoxin-resistant sodium channel Nav1.8 currents,and shifted the steady-state inactivation curves of Nav1.8 in a hyperpolarizing direction.GDF-15 also reduced window currents and slowed down the recovery rate of Nav1.8 channels,suggesting that GDF-15 accelerated inactivation and slowed recovery of the channel.Immunohistochemistry results showed that activin receptor-like kinase-2(ALK2)was widely expressed in DRG medium-and small-diameter neurons,and some of them were Nav1.8-positive.Blockade of ALK2 prevented the GDF-15-induced inhibition of Nav1.8 currents and nociceptive behaviors.Inhibition of PKA and ERK,but not PKC,blocked the inhibitory effect of GDF-15 on Nav1.8 currents.These results suggest a functional link between GDF-15 and Nav1.8 in DRG neurons via ALK2 receptors and PKA associated with MEK/ERK,which mediate the peripheral analgesia of GDF-15.
文摘Objective To observe the effects of glutamate on sodium channel in acutely dissociated hippocampal CA1 pyramidal neurons of rats.Methods Voltage-dependent sodium currents (INa) in acutely dissociated hippocampal CA1 pyramidal neurons of neonate rats were recorded by whole-cell patchclamp of the brain slice technique when a series of doses of glutamate (100-1000μmol/L) were applied.Results Different concentrations of glutamate could inhibit INa,and higher concentration of glutamate affected greater inhibition.In same concentration on INa at different times,longer time glutamate affected greater inhibition.And glutamate could significantly shift activation curve of INa to the right and make inactivation curve of INa negative drift.Conclusion Glutamate can inhibit voltage-dependent sodium channel.Its blockage on INa has voltage-dependent,time-dependent,and dose-dependent characteristics.
