Standardized Centella asiatica extract ECa 233 alleviates pain hypersensitivity by modulating P2X3 in trigeminal neuropathic pain

Abstract During oral surgery and temporomandibular joint repositioning, pain hypersensitivity often occurs due to irritation or inflammation of the nerve endings in the orofacial region. Objective: This study aimed to investigate the effects of ECa 233, a Centella asiatica-standardized extract, on the development of mechanical hyperalgesia and allodynia induced by chronic constriction injury of the infraorbital nerve in mice. Methodology: The right infraorbital nerves of the mice were ligated. Oral carbamazepine (20 mg/kg) or ECa 233 (30, 100, or 300 mg/kg) was administered daily for 21 days. Von Frey and air-puff tests were performed on both sides of the whisker pad on days 0, 7, 14, and 21. Thereafter, the expression of purinergic receptor subtype 3 (P2X3) and voltage-gated sodium channel 1.7 (NaV1.7), a transmembrane protein, in the trigeminal ganglion and c-fos immunoreactivity-positive neurons in the trigeminal nucleus caudalis was assessed. Results: After 21 days of infraorbital nerve ligation, the mice showed allodynia- and hyperalgesia-like behavior, P2X3 and NaV1.7 were upregulated in the trigeminal ganglion, and nociceptive activity increased in the trigeminal nucleus caudalis. However, the oral administration of carbamazepine (20 mg/kg), ECa 233 (100 mg/kg), or ECa 233 (300 mg/kg) mitigated these effects. Nevertheless, ECa 233 failed to affect NaV1.7 protein expression. Conclusion: Carbamazepine and ECa 233 can prevent pain hypersensitivity in mice. Considering the side effects of the long-term use of carbamazepine, ECa 233 monotherapy or combined ECa 233 and carbamazepine therapy can be used as an alternative for regulating the development of hypersensitivity in trigeminal pain. However, further detailed clinical studies should be conducted to provide comprehensive information on the use of ECa 233.

PTPRN mediates endocytosis of NaV1.2 sodium chan-nels and suppresses epileptogenesis in mice / 中国药理学与毒理学杂志

Epilepsy is a disorder of the brain charac-terized by abnormal neuron excitability.However,the underlying molecular mechanism of neuron excitability modulation remains elusive.With the help of bioinformatic methods,we have identified receptor-type tyrosine-pro-tein phosphatase-like N(PTPRN)as a critical gene dur-ing epileptogenesis.PTPRN recruits NEDD4L ubiquitin E3 ligase to NaV1.2 sodium channels,facilitating NEDD4L-mediated ubiquitination and endocytosis.Knockout of PTPRN endows hippocampal granule cells with augmented depolarization currents and higher intrinsic excitability,which is reflected by increased seizure susceptibility of transgenic mice.On the contrary,reduced neuron excit-ability and decreased seizure susceptibility are observed after PTPRN overexpression.Meanwhile,we find that a 133 aa fragment recaptures modulation effect of PTPRN full-length,and this fragment shows therapeutic potential towards epilepsy caused by NaV1.2 gain of function vari-ants.In brief,our results demonstrate PTPRN playsa criti-calroleinregulatingneuronexcitability,providing a poten-tial therapeutic approach for epilepsy.

nNav1.5 expression is associated with glutamate level in breast cancer cells

Abstract Background: Glutamate and voltage-gated sodium channels, both have been the target of intense investigation for its involvement in carcinogenesis and progression of malignant disease. Breast cancer with increased level of glutamate often metastasize to other organs (especially bone), whilst re-expression of 'neonatal' Nav1.5, nNav1.5 in breast cancer is known to promote cell invasion in vitro, metastasis in vivo and positive lymph node metastasis in patients. Methods: In this study, the role of nNav1.5 in regulating glutamate level in human breast cancer cells was examined using pharmacological approach (VGSCs specific blocker, TTX, glutamate release inhibitor, riluzole and siRNA-nNav1.5). Effect of these agents were evaluated based on endogenous and exogenous glutamate concentration using glutamate fluorometric assay, mRNA expression of nNav1.5 using qPCR and finally, invasion using 3D culture assay. Results: Endogenous and exogenous glutamate levels were significantly higher in aggressive human breast cancer cells, MDA-MB-231 cells compared to less aggressive human breast cancer cells, MCF-7 and non-cancerous human breast epithelial cells, MCF-10A. Treatment with TTX to MDA-MB-231 cells resulted in significant reduction of endogenous and exogenous glutamate levels corresponded with significant suppression of cell invasion. Subsequently, downregulation of nNav1.5 gene was observed in TTX-treated cells. Conclusions: An interesting link between nNav1.5 expression and glutamate level in aggressive breast cancer cells was detected and requires further investigation.

Sodium Channel NaV1. 7 and Neuropathic Pain / 中国生物化学与分子生物学报

Sodium channel Nav1. 7 is one of the subtypes of voltage-gated sodium channel. Most of it is expressed on the nociceptors of small C fibers in dorsal root ganglion (DRG). It has the characteristics of slow opening and slow closing of inactivation. It can produce a large amount of ramp current, reduce the threshold of action potential in sensory neurons, and amplify the external small and slow depolarization ramp current. Thus, it can increase the excitability of neurons and play a key role in the generation, transmission and regulation of pain. With the deepening of genetic research, Nav1. 7 channel has become a particularly attractive drug target in new analgesic therapy due to its function acquired mutation and function deletion mutation. However, the study found that Nav1. 7 channel improves neuronal excitability and participates in neuropathic pain through different ways in neuropathic pain caused by different factors, which has brought great obstacles to the research and development of Nav1. 7 selective inhibitors. Although the existing Nav1. 7 selective inhibitors have effective analgesic effects without obvious side effects or addiction problems, it is extremely difficult to find Nav1. 7 selective ligands. In addition, the existing Nav1. 7 selective inhibitors also differ in inhibitory efficacy, targeting, safety and feasibility due to different types of neuropathic pain. It is suggested that finding the general mechanism of Nav1. 7 channel acting on different neuropathic pain or the specific receptor binding site of Nav1. 7 channel may be the main direction of the research and development of Nav1. 7 selective inhibitors in the future. This paper briefly reviews the main role of Nav1. 7 channel in neuropathic pain caused by different factors.

Isolation, identification and electrophysiological activity of BmK M2 from Buthus martensii Karsch venom / 中国药科大学学报

@#This study aimed to isolate and identify novel toxin peptides targeting voltage-gated sodium channels (VGSGs) from the venom of the Buthus martensii Karsch (BmK) scorpion. Using G50-gel filtration, HPLC, peptide fingerprinting and amino acid sequencing, a novel sodium channel modulator, BmK M2, was identified from BMK scorpion. BmK M2 is a relatively abundant long chain polypeptide toxin in BmK scorpion venom with a molecular weight of 7 235.59, consisting of 64 amino acids and 4 pairs of disulfide bonds.Sequence alignment showed that the amino acid sequence of BmK M2 had high sequence and structural similarity to that of the discovered sodium channel toxins of BmK M1, BmK M3 and BmK M9, etc.BmK M2 is a potential new sodium channel modulator.Electrophysiological results revealed that BmK M2 can significantly enhance the activation, delay the steady-state inactivation and closed-state inactivation of Nav1.7, but has no activity on Nav1.8.BmK M2 can be used as a novel peptide probe for the study of the structure and function of Nav1.7 and the development of drugs targeting Nav1.7.

Growth Differentiation Factor-15 Produces Analgesia by Inhibiting Tetrodotoxin-Resistant Nav1.8 Sodium Channel Activity in Rat Primary Sensory Neurons / 神经科学通报·英文版

Growth differentiation factor 15 (GDF-15) is a member of the transforming growth factor-β superfamily. 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.

Growth Differentiation Factor-15 Produces Analgesia by Inhibiting Tetrodotoxin-Resistant Nav1.8 Sodium Channel Activity in Rat Primary Sensory Neurons / 神经科学通报·英文版

Growth differentiation factor 15 (GDF-15) is a member of the transforming growth factor-β superfamily. 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.

Epilepsia refractaria con convulsiones febriles plus en niños con mutaciones de la subunidad alfa de canales de sodio (SCN1A): un reporte de caso / Refractory epilepsy with febrile seizures in a child with sodium channel alpha subunit mutation (SCN1A): A case report

RESUMEN Se presenta caso de una niña de 10 años con cuadro de epilepsia mioclónica juvenil severa en la infancia, que a los 6 meses de edad debutó con crisis tónico-clónicas generalizadas (TCG) luego de la administración de una dosis de vacuna DPT, con posteriores crisis TCG, mioclónicas y múltiples episodios de estado epiléptico refractarios a fármacos antiepilépticos (FAE) de primera y segunda línea durante los primeros 5 años. Las crisis se asociaron a retraso global en el desarrollo luego del primer episodio. Durante la evolución se realizaron estudios que incluyen resonancia magnética cerebral que fue normal y tomografía por emisión de positrones (PET-CT) que evidenció alteraciones en el metabolismo en región temporal izquierda, además de estudios para inmunodeficiencias y trombofilias sin alteraciones. Los electroencefalogramas iniciales fueron normales, pero video electroencefalograma de 12 horas mostró actividad irritativa en la región central con diseminación bilateral. Los estudios genéticos identificaron una mutación en el marco de lectura de tipo "frameshift" del gen SCN1A mediante secuenciación de la región codificante. Luego de los primeros años de vida, la paciente presenta, atípicamente, remisión progresiva de las crisis con posterior desmonte de FAE y mejoría del neuro-desarrollo en el proceso interdisciplinario de rehabilitación.

SUMMARY We report the case of a 10-year-old female with a history of severe myoclonic epilepsy of infancy who presents with generalized tonic-clonic (GTC) seizures at 6 months of age after administration of a DPT vaccine, who then begins to present frequent and severe GTC seizures, myoclonic seizures and multiple refractory status epilepticus poorly controlled with first and second line anti-epileptic drugs (AEDs). This was accompanied by development delay. Studies performed on the patient included brain MRI which was normal, immunodeficiency and trombophilic studies which were normal and electroencephalographs: studies (EEG) that were at first mostly normal. The most significant findings were seen during a 12-hour video-EEG which reported epileptogenic activity in central region with bilateral dissemination and a PET-CT that showed metabolism alterations in the left temporal region. Due to this presentation a channelopathy was suspected and a coding region sequentiation study was performed which identified a frameshift mutation of the SCN1A gene confirming the diagnosis. Atipically, after 5 years the patient begins to present a favorable evolution with significant seizure remission even allowing the progressive weaning of AEDs and a remarkable stalemate of developmental delay after interdisciplinary rehabilitation process was started.

Design, synthesis and biological evaluation of novel α-aminoamide derivatives / 国际药学研究杂志

Objective: To design and synthesize novel α-aminoamide derivatives for the treatment of neuropathic pain. Methods: Ralfinamide was used as a lead compound, and it's ring A was replaced by a benzoheterocyclic moiety(2, 3-dihydrobenzofuran or 2, 3-dihydrobenzo[b][1, 4]dioxin)to obtain the new compounds 5a-5f. The in vivo and in vitro analgesic activities of the new compounds were evaluated by the formalin test and the whole-cell patch clamp assay, respectively. Results: In the formalin test in vivo, compound 5e exhibited higher analgesic activities(60% higher)than ralfinamide(P<0.05). The whole-cell patch clamp assay showed that the inhibitory effect of all tested compounds, except for 5d, on sodium channel Nav1.7 was much weaker than ralfinamide (P<0.05 or P<0.01). Conclusion: A set of new compounds with better analgesic activities than ralfinamide were obtained via optimizing the structure of ring A of ralfinamide. The reults of this study can provide useful references for relative research.

Role of Nav1.3 in control of excitability of RIN-14B cells / 上海交通大学学报（医学版）

Objective: To provide electrophysiological evidence for RIN-14B cells as an useful model of enterochromaffin cells (EC) and to study the role of Nav1. 3 channel in the control of its excitability. Methods: Resting membrane potential was recorded and the effects of TTX and ICA-121431 were examined by current-clamp in cultured RIN-14B cells. The effects of TTX and ICA-121431 on Na+ current of RIN-14B cells were examined by voltage-clamp. Results: RIN-14B cells had a resting potential around -60 mV and fired action potentials when stimulated with depolarizing current pulses. The action potential was completely blocked by TTX and inhibited by ICA-121431 in a dose-dependent manner. TTX blocked activation and inactivation of sodium current. In addition ICA-121431 dose-dependently inhibited activation of Na+ current. Conclusion: The action potential of RIN-14B cells is induced by TTX-sensitive sodium channel and the excitability is controlled by Nav1.3. These results suggest RIN-14B cells are similar to EC and it may be a good model of EC.

Mechanism of dexmedetomidine-induced reduction of acute visceral pain in rats: relationship be-tween α2 adrenergic receptors and expression of Nav1. 8 in dorsal root ganglion neurons / 中华麻醉学杂志

Objective To evaluate the relationship betweenα2 adrenergic receptors and expression of Nav1. 8 in dorsal root ganglion (DRG) neurons, and to illuminate the mechanism of dexmedetomidine-induced reduction of acute visceral pain in rats. Methods Thirty-two clean-grade healthy adult male Spra-gue-Dawley rats, aged 6-8 weeks, weighing 180-220 g, were divided into 4 groups ( n=8 each) using a random number table method: control group ( group C ) , acute visceral pain group ( group VP ) , dexmedetomidine group (group D), and dexmedetomidine plus atipamezole group (group DA). In VP, D and DA groups, 10-3 mmol∕L capsaicin 1. 3 ml was injected into the rectum at a dose of 10-3 mmol∕L to establish the acute visceral pain model, while the equal volume of normal saline was given instead in group C. Atipamezole 1 mg∕kg was subcutaneously injected through the back of the neck at 20 min before establishing the model in group DA. Dexmedetomidine 10μg∕kg was injected through the tail vein at 15 min before establishing the model in D and DA groups, while the equal volume of normal saline was given instead at the correspording time points in C and VP groups. The visceral pain behavior score was recorded at 1 h after establishing the model. The animals were then sacrificed, and DRGs of the lumbar segment (L3-6) were removed for determination of the number of Nav1. 8 positive DRG neurons (by immunohisto-chemistry) and expression of Nav1. 8 mRNA (by quantitative real-time polymerase chain reaction). Results Compared with group C, the visceral behavior scores and the number of Nav 1. 8 positive DRG neurons were significantly increased, and the expression of Nav 1. 8 mRNA was up-regulated in VP, D and DA groups (P<0. 05). Compared with group VP, the visceral behavior score and the number of Nav1. 8 positive DRG neurons were significantly decreased, and the expression of Nav 1. 8 mRNA was down-regulated in D and DA groups (P<0. 05). Compared with group D, the visceral behavior scores and the number of Nav1. 8 positive DRG neurons were significantly increased, and the expression of Nav1. 8 mRNA was up-regulated in group DA ( P<0. 05) . Conclusion The mechanism by which dexmedetomidine reduces acute visceral pain is related to activatingα2 adrenergic receptors and to down-regulating the expression of Nav1. 8 in DRG neu-rons of rats.

Effect of miR-145 on diabetic neuropathic pain by down-regulating Nav1.8 / 临床麻醉学杂志

Objective To observe the effect of miR-145 on pain threshold and explore the pos-sible underlying positive role of miR-145 in rats with diabetic neuropathic pain.Methods The total of 36 rats with diabetic neuropathic pain were randomly divided into three groups respectively with nor-mal control group (group N)(n=12 for each group):diabetic neuropathic pain(DNP)group (group D),DNP-NC group (group DN)and DNP-agomiR-145 group (group agomiR-145).The rats received agomiR-145 intrathecal injection in group agomiR-145 (10 μl,1×106TU/ml),or the negative control virus in group DN (10 μl,1×106TU/ml),or equal volume of normal saline in other two groups. Paw mechanical withdrawal threshold(MWT)and paw withdrawal latency(TWL)were measured on the day before intrathecal injection and day 1,days 3,7 and 14 after intrathecal injection.On the days 14 after pain-related behavioral test,the RNA expression of miR-145 in the dorsal root ganglion (DRG)was detected using reverse transcription-quantitative polymerase chain reaction(RT-PCR)as-say and the expression of Nav 1.8 in DRG were detected by fluorescent immunofluorescence.In addi-tion,a dual luciferase activity assay was used to testify the target genes of miR-145.Results MWT and TWL were decreased at 1 d before intrathecal injectionin groups D,DN and agomiR-145 than that in group N (P<0.05).The significant increase of MWT was observed in group agomiR-145 on day 3,7,14 than those in group D and group DN (P<0.05).TWL in group agomiR-145 was increased significantly on day 7 and day 14 compared with those in groups D and DN (P<0.05).Compared with group N,miR-145 expression level in DRG in groups D and DN were significantly lower (P<0.05).In addition,the protein expression of Nav1.8 was significantly increased in group D and DN compared with that in group N (P<0.05).Compared with groups D and DN,miR-145 expression was increased significantly and the expression of Nav1.8 in DRG was decreased significantly in group agomiR-145 (P<0.05).In addition,a dual luciferase reporter assay demonstrated that miR-145 can bind with the 3'-UTR region of Nav1.8 and regulate its expression.Conclusion Intrathecal agomiR-145 can effectively attenuate neuropathic pain of DNP rats,which may be related with down-regulation of Nav1.8 in DRG..

An experimental research on the analgesic effect and underlying mechanism of BTX-A for rat knee osteoarthritis / 中国康复医学杂志

Objective:To evaluate the analgesic effect of botulinum toxin type A (BTX-A) in osteoarthritis model and the changes of Nav1.8 protein expression in spinal ganglia changes.Method:Animal model of knee osteoarthritis (KOA) was established by intra-articular injection of 4％ papain solution 0.3ml into SD rat right knee.After the formation of arthritis,they were randomly divided into two groups at the 2nd day:BTX-A group (n=10):intra-articular injection of 5μl BTX-A 0.1IU;WFI group (n=10):intra-articular injection of 5μl water.No papain or BXT-A was given to the sham group (n=10).At the 1st,3rd,5th day after injection,we tested the pain behavior,thermal pain threshold,and sodium channel 1.8 (Nav1.8) protein expression in spinal ganglion by using immunohistochemistry.Result:Analysis of spontaneous pain behavior showed abnormal gait caused by rat osteoarthritis.Comparing with the WFI group,abnormal gait caused by osteoarthritis improved significantly in BTX-A group.At day 5 it improved more significantly than day 1 and day 3.Thermal pain threshold of BTX-A group increased more than that of WFI group (P＜0.05) at any time point.Abnormal high Nav1.8 protein in model rats decreased in spinal ganglia for BTX-A group.Conclusion:The intra-articular injection of BTX-A may play the analgesic effect in the model of KOA by down-regulating of the expression of Nav1.8 protein in spinal ganglia and reduction in the central sensitization to pain stimulation.

Structure-based assessment of disease-related mutations in human voltage-gated sodium channels

Voltage-gated sodium (Na) channels are essential for the rapid upstroke of action potentials and the propagation of electrical signals in nerves and muscles. Defects of Na channels are associated with a variety of channelopathies. More than 1000 disease-related mutations have been identified in Na channels, with Na1.1 and Na1.5 each harboring more than 400 mutations. Na channels represent major targets for a wide array of neurotoxins and drugs. Atomic structures of Na channels are required to understand their function and disease mechanisms. The recently determined atomic structure of the rabbit voltage-gated calcium (Ca) channel Ca1.1 provides a template for homology-based structural modeling of the evolutionarily related Na channels. In this Resource article, we summarized all the reported disease-related mutations in human Na channels, generated a homologous model of human Na1.7, and structurally mapped disease-associated mutations. Before the determination of structures of human Na channels, the analysis presented here serves as the base framework for mechanistic investigation of Na channelopathies and for potential structure-based drug discovery.

Is there a role for voltage-gated Na+ channels in the aggressiveness of breast cancer?

Breast cancer is the most common cancer among women and its metastatic potential is responsible for numerous deaths. Thus, the need to find new targets for improving treatment, and even finding the cure, becomes increasingly greater. Ion channels are known to participate in several physiological functions, such as muscle contraction, cell volume regulation, immune response and cell proliferation. In breast cancer, different types of ion channels have been associated with tumorigenesis. Recently, voltage-gated Na+ channels (VGSC) have been implicated in the processes that lead to increased tumor aggressiveness. To explain this relationship, different theories, associated with pH changes, gene expression and intracellular Ca2+, have been proposed in an attempt to better understand the role of these ion channels in breast cancer. However, these theories are having difficulty being accepted because most of the findings are contrary to the present scientific knowledge. Several studies have shown that VGSC are related to different types of cancer, making them a promising pharmacological target against this debilitating disease. Molecular biology and cell electrophysiology have been used to look for new forms of treatment aiming to reduce aggressiveness and the disease progress.

Expression of Nav1.6 in oral leukoplakia and oral squamous cell carcinoma / 实用口腔医学杂志

Objective:To study the expression and significance of sodium channel Nav1.6 in oral leukoplakia and squamous cell carcinoma.Methods:Immunohistochemistry and Western blot were used to detect the expression of Nav1.6 in 21 case of normal oral mucosa,32 of oral leukoplakia and 63 of oral squamous cell carcinoma(OSCC).Results:Immunohistochemical results showed that the positive rate of Nay1.6 in normal group,oral leukoplakia group and OSCC group was 6.25％,40％ and 76.74％ respectively.The expression of Nav1.6 was related to the differentiation of oral squamous cell carcinoma.Western blot results revealed that the content of Nav1.6 in normal oral mucosa,oral leukoplakia and OSCC was 0.469 ±0.015,0.545 ±0.016 and 0.848 ±0.020(P ＜0.05) respectively.Conclusion:Nay1.6 may play a role in the development of OSCC.

Mutation (Thr704Met) of the SCN4A gene causes severe familial hypokalemic periodic paralysis / 中华神经科杂志

Objective To investigate the clinical features and pathogenic genes of a familial hypokalemic periodic paralysis ( HOKPP).Methods PCR amplification and DNA sequencing were used to screen candidate genes of the HOKPP family members (CACNA1S, SCN4A, KCNE3), and the clinical features were carefully analyzed at the same time.Results The sequencing analyses of the SCN4A gene in the proband identified three nucleotide sequence mutations, which influenced the amino acid sequence of the skeletal sodium channel.One of the mutations was identified as a C/T heterozygous pattern at the 2111th nucleotide position in exon 13, resulting in a change from Thr to Met at the 704th amino acid position of the sodium channel protein.All affected patients carried the Thr704Met mutation, whereas unaffected family members did not.Clinical symptoms in this family followed an autosomal dominant inheritance pattern.Muscles weakness, pain and hypokalemia in the period between attacks were seen in all patients.Paralytic symptoms occurred early, lasted longer and recurred frequently, while cold was the main predisposing factor.With the progress of the disease, patients represented persistent weakness and atrophy in proximal muscles.Conclusions Mutation (Thr704Met) in the SCN4A gene should be responsible for this family.This mutation causes severe HOKPP and progressive muscle atrophy.

Research progress in voltage-gated sodium channels and tumor / 肿瘤

Voltage-gated sodium channels (VGSCs) are heteromeric protein complexes containing one core subunit α and one or more auxiliary subunit β. VGSCs are widely expressed in various forms of tumor cells and tissues. Importantly, subunit α can regulate the invasive capacity of tumor cells, and subunit β is related to the adhesion and migration capacities of tumor cells. The function of subunit β in different types of tumor is different. Emerging studies have revealed that VGSCs have certain effects on tumor invasion and metastasis, which indicates that VGSCs may become the target for tumor diagnosis and targeted therapy. Therefore, this paper summarizes the effects of VGSCs on tumor invasion and migration, as well as the research progress in VGSCs used as tumor therapeutic target.

Expression of Adult and Neonatal Nav1.5 Isoforms in the Dorsal Root Ganglia Neurons of Rats with Spared Nerve Injury / 沈阳医学院学报

Objective:To study the expression of adult and neonatal Nav1.5 isoforms in the dorsal root ganglia (DRG) neurons of rats with spared nerve injury (SNI) . Methods:The expression of adult and neonatal Nav1.5 isoforms in the DRG neurons of rats with SNI was detected by RT-PCR, DNA sequencing, restriction enzyme digestion, immunohistochemistry and immunofluo-rescence methods. The expression of PKC-γwas detected by Western blot. Results:Both adult and neonatal Nav1.5 isoforms were expressed in the DRG neurons, but their expression ratio was approximately 2.5∶1. In SNI rat models, the expression of both adult and neonatal Nav1.5 isoforms decreased by approximately a half in both mRNA and protein levels. In contrast, the expression of PKC-γincreased by approximately one-fold. Conclusions:Both adult and neonatal Nav1.5 isoforms expressed in the DRG neurons of rat,but their expression levels decrease in pain models. The up-regulation of PKC-γmay directly or indirectly down-regulate the expression of Nav1.5 isoforms in SNI rat models,which may further involve in the pathological process of neuropathic pain.

Inhibitory effects of neferine on Nav1.5 channels expressed in HEK293 cells / 华中科技大学学报（医学）（英德文版）

Neferine, a bisbenzylisoquinoline alkaloid in Lotus Plumule, was proved to have a wide range of biological activities. In the present study, using whole-cell patch-clamp technique, we investigated the effects of neferine on Nav1.5 channels that are stably expressed in HEK 293 cells. We found that neferine potently and reversibly inhibited Nav1.5 currents in a concentration dependent manner with a half-maximal inhibition (IC50) being 26.15 μmol/L. The inhibitory effects of neferine on Nav1.5 currents were weaker than those of quinidine at the same concentration. The steady-state inactivation curve was significantly shifted towards hyperpolarizing direction in the presence of 30 μmol/L neferine, while the voltage-dependent activation was unaltered. Neferine prolonged the time to peak of activation, increased the inactivation time constants of Nav1.5 currents and markedly slowed the recovery from inactivation. The inhibitory effect of neferine could be potentiated in a frequency-dependent manner. These results suggested that neferine can block Nav1.5 channels under the open state and inactivating state and it is an open channel blocker of Nav1.5 channels.