Numerous pathological states of the nervous system involve alterations in neuronal excitability and synaptic dysfunction,which depend on the function of ion channels.Due to their critical involvement in health and dis...Numerous pathological states of the nervous system involve alterations in neuronal excitability and synaptic dysfunction,which depend on the function of ion channels.Due to their critical involvement in health and disease,the search for new compounds that modulate these proteins is still relevant.Traditional medicine has long been a rich source of neuroactive compounds.For example,the indigenous Mapuche people have used the leaves and bark of the Drimys winteri tree for centuries to treat various diseases.Consequently,several studies have investigated the biological effects of compounds in Drimys winteri,highlighting sesquiterpenes such asα-humulene,drimenin,polygodial,andα-,β-,γ-eudesmol.However,there is currently no literature review focusing on the ability of these sesquiterpenes to modulate ion channels.This review summarizes the current knowledge about neuroactive compounds found in Drimys winteri,with special emphasis on their direct actions on neuronal ion channels.Several Drimys winteri sesquiterpenes modulate a diverse array of neuronal ion channels,including transient receptor potential channels,gamma-aminobutyric acid A receptors,nicotinic acetylcholine receptors,and voltage-dependent Ca^(2+)and Na^(+)channels.Interestingly,the modulation of these molecular targets by Drimys winteri sesquiterpenes correlates with their therapeutic actions.The promiscuous pharmacological profile of Drimys winteri sesquiterpenes suggests they modulate multiple protein targets in vivo,making them potentially useful for treating complex,multifactorial diseases.Further studies at the molecular level may aid in developing multitargeted drugs with enhanced therapeutic effects.展开更多
In the clinical reports, the E1784K mutation in SCN5A is recognized as a phenotypic overlap between the long QT syndrome （LQT3） and the Brugada syndrome （BrS） in the characteristics of electrocardiograms （ECGs） ...In the clinical reports, the E1784K mutation in SCN5A is recognized as a phenotypic overlap between the long QT syndrome （LQT3） and the Brugada syndrome （BrS） in the characteristics of electrocardiograms （ECGs） since the mutation can influence sodium channel functions. However it is still unclear if the E1784K mutation-induced sodium ionic channel alterations account for the overlap at tissue level. Thsu, a detailed computational model is developed to underpin the functional impacts of the E1784K mutation on the action potential （AP）, the effective refractory period （ERP） and the abnormal ECG. Simulation results stlggest＇that the E1784K mutation-induced sodium channel alterations are insufficient to produce the phenotypic overlap between LQT3 and BrS, and the overlap may arise from the complicated effects of the E1784K mutation-induced changes in sodium channel currents with an increase of the transient outward current ITo or a decrease of the L-type calcium current ICaL .展开更多
Isoflavones are widely consumed by people around the world in the form of soy products, dietary supplements and drugs. Many isoflavones or related crude extracts have been reported to exert pain-relief activities, but...Isoflavones are widely consumed by people around the world in the form of soy products, dietary supplements and drugs. Many isoflavones or related crude extracts have been reported to exert pain-relief activities, but the mechanism remains unclear. Voltage-gated sodium channels(VGSCs) play important roles in excitability of pain sensing neurons and many of them are important nociceptors. Here, we report that several isoflavones including 3’-methoxydaidzein(3 MOD), genistein(GEN) and daidzein(DAI) show abilities to block VGSCs and thus to attenuate chemicals and heat induced acute pain or chronic constriction injury(CCI) induced pain hypersensitivity in mice. Especially, 3 MOD shows strong analgesic potential without inducing addiction through inhibiting subtypes NaV1.7, NaV1.8 and NaV1.3 with the IC50 of 181 ± 14, 397 ± 26, and 505 ± 46 nmol·L–1, respectively, providing a promising compound or parent structure for the treatment of pain pathologies. This study reveals a pain-alleviating mechanism of dietary isoflavones and may provide a convenient avenue to alleviate pain.展开更多
Voltage-gated sodium channels （Navs） play an important role in human pain sensation. However, the expression and role of Nav subtypes in native human sensory neurons are unclear. To address this issue, we obtained h...Voltage-gated sodium channels （Navs） play an important role in human pain sensation. However, the expression and role of Nav subtypes in native human sensory neurons are unclear. To address this issue, we obtained human dorsal root ganglion （hDRG） tissues from healthy donors. PCR analysis of seven DRG-expressed Nav subtypes revealed that the hDRG has higher expression of Navl.7 （,-~ 50% of total Nav expression） and lower expres- sion of Navl.8 （~ 12%）, whereas the mouse DRG has higher expression of Nav 1.8 （- 45%） and lower expression of Navl.7 （- 18%）. To mimic Nav regulation in chronic pain, we treated hDRG neurons in primary cultures with paclitaxel （0.1-1 μmol/L） for 24 h. Paclitaxel increased the Navl.7 but not Navl.8 expression and also increased the transient Na＋ currents and action potential firing frequency in small-diameter （〈50 ~tm） hDRG neurons. Thus, the hDRG provides a translational model in which to study ＂human pain in a dish＂ and test new pain therapeutics.展开更多
Objective To examine the effect of deglycosylation on gating properties of rNav1.3. Methods rNav1.3 was expressed in Xenopus oocyte, with glycosylation inhibition by using tunicamycin. Two-electrode voltage clamp was ...Objective To examine the effect of deglycosylation on gating properties of rNav1.3. Methods rNav1.3 was expressed in Xenopus oocyte, with glycosylation inhibition by using tunicamycin. Two-electrode voltage clamp was employed to record the whole-cell sodium current and data were analyzed by Origin software. Those of glycosylated rNav1.3 were kept as control. Results Compared with glycosylated ones, the steady-state activation curve of deglycosylated rNav1.3 was positively shifted by about 10 mV, while inactivation curve was negatively shifted by about 8 mV. Conclusion Glycosylation altered the gating properties of rNav 1.3 and contributed to the functional diversity.展开更多
Objective Ligustrazine, also named as tetramethylpyrazine, is a compound purified from Ligusticum chuanxiong hort and has ever been testified to be a calcium antagonist. The present investigation was to determine the ...Objective Ligustrazine, also named as tetramethylpyrazine, is a compound purified from Ligusticum chuanxiong hort and has ever been testified to be a calcium antagonist. The present investigation was to determine the antinociceptive effect of ligustrazine and, if any, the peripheral ionic mechanism involved. Methods Paw withdrawal Latency （PWL） to noxious heating was measured in vivo and whole-cell patch recording was performed on small dorsal root ganglion （DRG） neurons. Results Intraplantar injection of ligustrazine （0.5 mg in 25 μl） significantly prolonged the withdrawal latency of ipsilateral hindpaw to noxious heating in the rat. Ligustrazine not only reversibly inhibited high-voltage gated calcium current of dorsal root ganglion （DRG） neuron in dose-dependent manner with IC50 of 1.89 mmol/L, but also decreased tetrodotoxin （TTX） -resistant sodium current in relatively selective and dose-dependent manner with IC50 of 2.49 mmol/L. Conclusion The results suggested that ligustrazine could elevate the threshold of thermal nociception through inhibiting the high-voltage gated calcium current and TTX-resistant sodium current of DRG neuron .in the rat.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
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
Atrial fibrillation(AF)is the most common cardiac arrhythmia worldwide.The prevalence of the disease increases with age,strongly implying an age-related process underlying the pathology.At a time when people are livin...Atrial fibrillation(AF)is the most common cardiac arrhythmia worldwide.The prevalence of the disease increases with age,strongly implying an age-related process underlying the pathology.At a time when people are living longer than ever before,an exponential increase in disease prevalence is predicted worldwide.Hence unraveling the underlying mechanics of the disease is paramount for the development of innovative treatment and prevention strategies.The role of voltage-gated sodium channels is fundamental in cardiac electrophysiology and may provide novel insights into the arrhythmogenesis of AF.Na_v1.5 is the predominant cardiac isoform,responsible for the action potential upstroke.Recent studies have demonstrated that Na_v1.8(an isoform predominantly expressed within the peripheral nervous system)is responsible for cellular arrhythmogenesis through the enhancement of pro-arrhythmogenic currents.Animal studies have shown a decline in Na_v1.5 leading to a diminished action potential upstroke during phase 0.Furthermore,the study of human tissue demonstrates an inverse expression of sodium channel isoforms;reduction of Na_v1.5 and increase of Na_v1.8 in both heart failure and ventricular hypertrophy.This strongly suggests that the expression of voltage-gated sodium channels play a crucial role in the development of arrhythmias in the diseased heart.Targeting aberrant sodium currents has led to novel therapeutic approaches in tackling AF and continues to be an area of emerging research.This review will explore how voltage-gated sodium channels may predispose the elderly heart to AF through the examination of laboratory and clinical based evidence.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
The epithelial Na^＋ channel （ENaC） consists of α, β, γ subunits. Its expression and function are regulated by aldosterone at multiple levels including transcription. ENaC plays a key role in Na^＋ homeostasis a...The epithelial Na^＋ channel （ENaC） consists of α, β, γ subunits. Its expression and function are regulated by aldosterone at multiple levels including transcription. ENaC plays a key role in Na^＋ homeostasis and blood pressure. Mutations in ENaC subunit genes result in hypertension or hypotension, depending on the nature of the mutations. Transcription of αENaC is considered as the rate-limiting step in the formation of functional ENaC. As an aldosterone target gene, αENaC is activated upon aldosterone- mineralocorticoid receptor binding to the cis-elements in the αENaC promoter, which is packed into chromatin. However, how aldosterone alters chromatin structure to induce changes in transcription is poorly understood. Studies by others and us suggest that Dot1a-Af9 complex represses αENaC by directly binding and regulating targeted histone H3 K79 hypermethylation at the specific subregions of αENaC promoter. Aldosterone decreases Dot1a-Af9 formation by impairing expression of Dot1a and Af9 and by inducing Sgk1, which, in turn, phosphorylates Af9 at S435 to weaken Dot1a-Af9 interaction. MR attenuates Dot1a-Af9 effect by competing with Dot1a for binding Af9. Af17 relieves repression by interfering with Dot1a-Af9 interaction and promoting Dot1a nuclear export. Af17^-/- mice exhibit defects in ENaC expression, renal Na^＋ retention, and blood pressure control. This review gives a brief summary of these novel fndings.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
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
Selenocosmia huwena and Selenocosmia hainana are two tarantula species found in southern China.Their venoms contain abundant peptide toxins.Two new neurotoxic peptides,huwentoxin-Ⅲ(HWTX-Ⅲ) and hainantoxin-VI(HNTX-VI...Selenocosmia huwena and Selenocosmia hainana are two tarantula species found in southern China.Their venoms contain abundant peptide toxins.Two new neurotoxic peptides,huwentoxin-Ⅲ(HWTX-Ⅲ) and hainantoxin-VI(HNTX-VI),were obtained from the venom using ion-exchange chromatography and reverse-phase high performance liquid chromatography(RP-HPLC).The mechanism of action of HWTX-Ⅲ and HNTX-VI on insect neuronal voltage-gated sodium channels(VGSCs) was studied via whole-cell patch clamp techniques.In a fashion similar to δ-atracotoxins,HNTX-VI can induce a slowdown of current inactivation of the VGSC and reduction in the peak of Na+ current in cockroach dorsal unpaired median(DUM) neurons.Meanwhile,10 μmol/L HNTX-IV caused a positive shift of steady-state inactivation of sodium channel.HWTX-ⅡI inhibited VGSCs on DUM neurons(concentration of toxin at half-maximal inhibition(IC50)≈1.106 μmol/L) in a way much similar to tetrodotoxin(TTX).HWTX-Ⅲ had no effect on the kinetics of activation and inactivation.The shift in the steady-state inactivation curve was distinct from other depressant spider toxins.The diverse effect and the mechanism of action of the two insect toxins illustrate the diverse biological activities of spider toxins and provide a fresh theoretical foundation to design and develop novel insecticides.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
With the acceleration of population aging,heart disease has been a high priority,and cardiac ion channel research has been one of the hot spots in the field,Sodium ion channels,as the most important class,have been wi...With the acceleration of population aging,heart disease has been a high priority,and cardiac ion channel research has been one of the hot spots in the field,Sodium ion channels,as the most important class,have been widely concerned.Therefore,this paper briefly introduces and discusses three aspects of the structure and function of sodium ion channels and the development of drug research.展开更多
OBJECTIVE: To investigate whether the effect of loureirin B plus capsaicin on tetrodotoxin-resistant(TTX-R) sodium channel.METHODS: By using whole-cell patch-clamp recordings, in acutely isolated dorsal root ganglion(...OBJECTIVE: To investigate whether the effect of loureirin B plus capsaicin on tetrodotoxin-resistant(TTX-R) sodium channel.METHODS: By using whole-cell patch-clamp recordings, in acutely isolated dorsal root ganglion(DRG) neurons, the combined effects of loureirin B and capsaicin on TTX-R sodium channel were observed. Based on the data, the interaction between loureirin B and capsaicin in their modulation on TTX-R sodium channel was assessed.RESULTS: Loureirin B could not induce transient inward TRPV1 current. Capsazepine, a transient receptor potential vanilloid l(TRPV1) antagonist, could not attenuate the block of 0.64 mmol/L loureirin B on TTX-R sodium channel. There was no significant difference(P > 0.05) between IC_(50) of loureirin B(0.37 mmol/L) on TTX-R sodium channel in capsaicin-sensitive DRG neurons and that(0.38 mmol/L)in capsaicin-insensitive DRG neurons. However,there was a significant difference(P < 0.05) between the IC_(50) of capsaicin(0.28 μmol/L) on TTX-R sodium channel in capsaicin-sensitive DRG neurons and that(52.24 μmol/L) in capsaicin-insensitive DRG neurons. Four combinations composed of various concentrations of loureirin B and capsaicin could all inhibit TTX-R sodium currents but have different interactions between loureirin B and capsaicin.CONCLUSION: Loureirin B plus capsaicin could produce double blockage on TRPV1 and modulation on TTX-R sodium channel. The action of loureirin B onTTX-R sodium channel was independent ofTRPV1 but similar with that of capsaicin on TTX-R sodium channel in capsaicin-insensitive DRG neurons.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...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 LabmasterTLlwere 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
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
The velocity field of liquid sodium in a toroidal channel is studied.Velocity measurements are made using the magnetic induction method.The proposed technique involves two steps:an external alternating magnetic field ...The velocity field of liquid sodium in a toroidal channel is studied.Velocity measurements are made using the magnetic induction method.The proposed technique involves two steps:an external alternating magnetic field of certain frequency is induced in the channel;then the measurements of the resulting magnetic field are used to reconstruct the velocity profile.展开更多
基金supported by ANID-FONDECYT 1200908(to JF),ANID-FONDECYT 1211082 and 1250856(to GEY)by the Millennium Nucleus for the Study of Pain NCN19_038(Mi Nu SPain)(to GEY)funded by the ANID scholarship 21201176。
文摘Numerous pathological states of the nervous system involve alterations in neuronal excitability and synaptic dysfunction,which depend on the function of ion channels.Due to their critical involvement in health and disease,the search for new compounds that modulate these proteins is still relevant.Traditional medicine has long been a rich source of neuroactive compounds.For example,the indigenous Mapuche people have used the leaves and bark of the Drimys winteri tree for centuries to treat various diseases.Consequently,several studies have investigated the biological effects of compounds in Drimys winteri,highlighting sesquiterpenes such asα-humulene,drimenin,polygodial,andα-,β-,γ-eudesmol.However,there is currently no literature review focusing on the ability of these sesquiterpenes to modulate ion channels.This review summarizes the current knowledge about neuroactive compounds found in Drimys winteri,with special emphasis on their direct actions on neuronal ion channels.Several Drimys winteri sesquiterpenes modulate a diverse array of neuronal ion channels,including transient receptor potential channels,gamma-aminobutyric acid A receptors,nicotinic acetylcholine receptors,and voltage-dependent Ca^(2+)and Na^(+)channels.Interestingly,the modulation of these molecular targets by Drimys winteri sesquiterpenes correlates with their therapeutic actions.The promiscuous pharmacological profile of Drimys winteri sesquiterpenes suggests they modulate multiple protein targets in vivo,making them potentially useful for treating complex,multifactorial diseases.Further studies at the molecular level may aid in developing multitargeted drugs with enhanced therapeutic effects.
基金Supported by the National Natural Science Foundation of China(61001167,61172149)~~
文摘In the clinical reports, the E1784K mutation in SCN5A is recognized as a phenotypic overlap between the long QT syndrome （LQT3） and the Brugada syndrome （BrS） in the characteristics of electrocardiograms （ECGs） since the mutation can influence sodium channel functions. However it is still unclear if the E1784K mutation-induced sodium ionic channel alterations account for the overlap at tissue level. Thsu, a detailed computational model is developed to underpin the functional impacts of the E1784K mutation on the action potential （AP）, the effective refractory period （ERP） and the abnormal ECG. Simulation results stlggest＇that the E1784K mutation-induced sodium channel alterations are insufficient to produce the phenotypic overlap between LQT3 and BrS, and the overlap may arise from the complicated effects of the E1784K mutation-induced changes in sodium channel currents with an increase of the transient outward current ITo or a decrease of the L-type calcium current ICaL .
基金supported by Ministry of Science and Technology of China(Nos.2013CB911304 and 2014ZX0800949B-002)the National Natural Science Foundation of China(Nos.U1302221,31372208 and 31630075)+3 种基金Innovation Programe of Chinese Academy of Sciences(Nos.XDA12020340 and 2015CASEABRI002)Biological Resources Programme of Chinese Academy of Sciences(No.KFJ-BRP-008)the Natural Science Foundation of Yunnan Province(Nos.2015BC005,2016FA006 and 2015HA023)the Natural Science Foundation of Jiangsu Province(Nos.Q0201600440,BE2016742)
文摘Isoflavones are widely consumed by people around the world in the form of soy products, dietary supplements and drugs. Many isoflavones or related crude extracts have been reported to exert pain-relief activities, but the mechanism remains unclear. Voltage-gated sodium channels(VGSCs) play important roles in excitability of pain sensing neurons and many of them are important nociceptors. Here, we report that several isoflavones including 3’-methoxydaidzein(3 MOD), genistein(GEN) and daidzein(DAI) show abilities to block VGSCs and thus to attenuate chemicals and heat induced acute pain or chronic constriction injury(CCI) induced pain hypersensitivity in mice. Especially, 3 MOD shows strong analgesic potential without inducing addiction through inhibiting subtypes NaV1.7, NaV1.8 and NaV1.3 with the IC50 of 181 ± 14, 397 ± 26, and 505 ± 46 nmol·L–1, respectively, providing a promising compound or parent structure for the treatment of pain pathologies. This study reveals a pain-alleviating mechanism of dietary isoflavones and may provide a convenient avenue to alleviate pain.
基金supported in part by NIH RO1Grants NS87988,DE17794,and DE22743 to R.R.J and NS89479 to S.Y.L and R.R.J
文摘Voltage-gated sodium channels （Navs） play an important role in human pain sensation. However, the expression and role of Nav subtypes in native human sensory neurons are unclear. To address this issue, we obtained human dorsal root ganglion （hDRG） tissues from healthy donors. PCR analysis of seven DRG-expressed Nav subtypes revealed that the hDRG has higher expression of Navl.7 （,-~ 50% of total Nav expression） and lower expres- sion of Navl.8 （~ 12%）, whereas the mouse DRG has higher expression of Nav 1.8 （- 45%） and lower expression of Navl.7 （- 18%）. To mimic Nav regulation in chronic pain, we treated hDRG neurons in primary cultures with paclitaxel （0.1-1 μmol/L） for 24 h. Paclitaxel increased the Navl.7 but not Navl.8 expression and also increased the transient Na＋ currents and action potential firing frequency in small-diameter （〈50 ~tm） hDRG neurons. Thus, the hDRG provides a translational model in which to study ＂human pain in a dish＂ and test new pain therapeutics.
基金the National Basic Research Development Program of China (No. 2006CB500801).
文摘Objective To examine the effect of deglycosylation on gating properties of rNav1.3. Methods rNav1.3 was expressed in Xenopus oocyte, with glycosylation inhibition by using tunicamycin. Two-electrode voltage clamp was employed to record the whole-cell sodium current and data were analyzed by Origin software. Those of glycosylated rNav1.3 were kept as control. Results Compared with glycosylated ones, the steady-state activation curve of deglycosylated rNav1.3 was positively shifted by about 10 mV, while inactivation curve was negatively shifted by about 8 mV. Conclusion Glycosylation altered the gating properties of rNav 1.3 and contributed to the functional diversity.
文摘Objective Ligustrazine, also named as tetramethylpyrazine, is a compound purified from Ligusticum chuanxiong hort and has ever been testified to be a calcium antagonist. The present investigation was to determine the antinociceptive effect of ligustrazine and, if any, the peripheral ionic mechanism involved. Methods Paw withdrawal Latency （PWL） to noxious heating was measured in vivo and whole-cell patch recording was performed on small dorsal root ganglion （DRG） neurons. Results Intraplantar injection of ligustrazine （0.5 mg in 25 μl） significantly prolonged the withdrawal latency of ipsilateral hindpaw to noxious heating in the rat. Ligustrazine not only reversibly inhibited high-voltage gated calcium current of dorsal root ganglion （DRG） neuron in dose-dependent manner with IC50 of 1.89 mmol/L, but also decreased tetrodotoxin （TTX） -resistant sodium current in relatively selective and dose-dependent manner with IC50 of 2.49 mmol/L. Conclusion The results suggested that ligustrazine could elevate the threshold of thermal nociception through inhibiting the high-voltage gated calcium current and TTX-resistant sodium current of DRG neuron .in the rat.
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.
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.
文摘Atrial fibrillation(AF)is the most common cardiac arrhythmia worldwide.The prevalence of the disease increases with age,strongly implying an age-related process underlying the pathology.At a time when people are living longer than ever before,an exponential increase in disease prevalence is predicted worldwide.Hence unraveling the underlying mechanics of the disease is paramount for the development of innovative treatment and prevention strategies.The role of voltage-gated sodium channels is fundamental in cardiac electrophysiology and may provide novel insights into the arrhythmogenesis of AF.Na_v1.5 is the predominant cardiac isoform,responsible for the action potential upstroke.Recent studies have demonstrated that Na_v1.8(an isoform predominantly expressed within the peripheral nervous system)is responsible for cellular arrhythmogenesis through the enhancement of pro-arrhythmogenic currents.Animal studies have shown a decline in Na_v1.5 leading to a diminished action potential upstroke during phase 0.Furthermore,the study of human tissue demonstrates an inverse expression of sodium channel isoforms;reduction of Na_v1.5 and increase of Na_v1.8 in both heart failure and ventricular hypertrophy.This strongly suggests that the expression of voltage-gated sodium channels play a crucial role in the development of arrhythmias in the diseased heart.Targeting aberrant sodium currents has led to novel therapeutic approaches in tackling AF and continues to be an area of emerging research.This review will explore how voltage-gated sodium channels may predispose the elderly heart to AF through the examination of laboratory and clinical based evidence.
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.
基金Supported by National Institutes of Health Grant 2R01 DK080236 06A1
文摘The epithelial Na^＋ channel （ENaC） consists of α, β, γ subunits. Its expression and function are regulated by aldosterone at multiple levels including transcription. ENaC plays a key role in Na^＋ homeostasis and blood pressure. Mutations in ENaC subunit genes result in hypertension or hypotension, depending on the nature of the mutations. Transcription of αENaC is considered as the rate-limiting step in the formation of functional ENaC. As an aldosterone target gene, αENaC is activated upon aldosterone- mineralocorticoid receptor binding to the cis-elements in the αENaC promoter, which is packed into chromatin. However, how aldosterone alters chromatin structure to induce changes in transcription is poorly understood. Studies by others and us suggest that Dot1a-Af9 complex represses αENaC by directly binding and regulating targeted histone H3 K79 hypermethylation at the specific subregions of αENaC promoter. Aldosterone decreases Dot1a-Af9 formation by impairing expression of Dot1a and Af9 and by inducing Sgk1, which, in turn, phosphorylates Af9 at S435 to weaken Dot1a-Af9 interaction. MR attenuates Dot1a-Af9 effect by competing with Dot1a for binding Af9. Af17 relieves repression by interfering with Dot1a-Af9 interaction and promoting Dot1a nuclear export. Af17^-/- mice exhibit defects in ENaC expression, renal Na^＋ retention, and blood pressure control. This review gives a brief summary of these novel fndings.
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.
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.
基金supported by the National Natural Science Foundation of China (No.30500146)the National Basic Research Program (973) of China (No.2006CB708508)
文摘Selenocosmia huwena and Selenocosmia hainana are two tarantula species found in southern China.Their venoms contain abundant peptide toxins.Two new neurotoxic peptides,huwentoxin-Ⅲ(HWTX-Ⅲ) and hainantoxin-VI(HNTX-VI),were obtained from the venom using ion-exchange chromatography and reverse-phase high performance liquid chromatography(RP-HPLC).The mechanism of action of HWTX-Ⅲ and HNTX-VI on insect neuronal voltage-gated sodium channels(VGSCs) was studied via whole-cell patch clamp techniques.In a fashion similar to δ-atracotoxins,HNTX-VI can induce a slowdown of current inactivation of the VGSC and reduction in the peak of Na+ current in cockroach dorsal unpaired median(DUM) neurons.Meanwhile,10 μmol/L HNTX-IV caused a positive shift of steady-state inactivation of sodium channel.HWTX-ⅡI inhibited VGSCs on DUM neurons(concentration of toxin at half-maximal inhibition(IC50)≈1.106 μmol/L) in a way much similar to tetrodotoxin(TTX).HWTX-Ⅲ had no effect on the kinetics of activation and inactivation.The shift in the steady-state inactivation curve was distinct from other depressant spider toxins.The diverse effect and the mechanism of action of the two insect toxins illustrate the diverse biological activities of spider toxins and provide a fresh theoretical foundation to design and develop novel insecticides.
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.
文摘With the acceleration of population aging,heart disease has been a high priority,and cardiac ion channel research has been one of the hot spots in the field,Sodium ion channels,as the most important class,have been widely concerned.Therefore,this paper briefly introduces and discusses three aspects of the structure and function of sodium ion channels and the development of drug research.
基金Supported by the National Natural Science Foundation of China(No.81403186)National Science Foundation of Hubei Grants(No.2014CFB455)
文摘OBJECTIVE: To investigate whether the effect of loureirin B plus capsaicin on tetrodotoxin-resistant(TTX-R) sodium channel.METHODS: By using whole-cell patch-clamp recordings, in acutely isolated dorsal root ganglion(DRG) neurons, the combined effects of loureirin B and capsaicin on TTX-R sodium channel were observed. Based on the data, the interaction between loureirin B and capsaicin in their modulation on TTX-R sodium channel was assessed.RESULTS: Loureirin B could not induce transient inward TRPV1 current. Capsazepine, a transient receptor potential vanilloid l(TRPV1) antagonist, could not attenuate the block of 0.64 mmol/L loureirin B on TTX-R sodium channel. There was no significant difference(P > 0.05) between IC_(50) of loureirin B(0.37 mmol/L) on TTX-R sodium channel in capsaicin-sensitive DRG neurons and that(0.38 mmol/L)in capsaicin-insensitive DRG neurons. However,there was a significant difference(P < 0.05) between the IC_(50) of capsaicin(0.28 μmol/L) on TTX-R sodium channel in capsaicin-sensitive DRG neurons and that(52.24 μmol/L) in capsaicin-insensitive DRG neurons. Four combinations composed of various concentrations of loureirin B and capsaicin could all inhibit TTX-R sodium currents but have different interactions between loureirin B and capsaicin.CONCLUSION: Loureirin B plus capsaicin could produce double blockage on TRPV1 and modulation on TTX-R sodium channel. The action of loureirin B onTTX-R sodium channel was independent ofTRPV1 but similar with that of capsaicin on TTX-R sodium channel in capsaicin-insensitive DRG neurons.
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 LabmasterTLlwere 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Item Sponsored by RFBR Grant No.11-01-00423-aby Ministry of Education of Perm Region in the Frame of the Project"Creating and Laboratory Testing of the Software Package for Computer Simulation of Convective and Magnetohydrodynamic Processes in Rotating Systems"
文摘The velocity field of liquid sodium in a toroidal channel is studied.Velocity measurements are made using the magnetic induction method.The proposed technique involves two steps:an external alternating magnetic field of certain frequency is induced in the channel;then the measurements of the resulting magnetic field are used to reconstruct the velocity profile.
