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A major insecticide resistance mechanism in insect pests is knock‐down resistance (kdr) caused by mutations in the voltage‐gated sodium channel (Vgsc) gene. Despite being common in most malaria Anopheles vector species, kdr mutations have never been observed in Anopheles funestus, the principal malaria vector in Eastern and Southern Africa, with resistance mainly being conferred by detoxification enzymes. In a parallel study, we monitored 10 populations of An. funestus in Tanzania for insecticide resistance unexpectedly identified resistance to a banned insecticide, DDT, in the Morogoro region. Through whole‐genome sequencing of 333 An. funestus samples from these populations, we found eight novel amino acid substitutions in the Vgsc gene, including the kdr variant, L976F (equivalent to L995F in An. gambiae), in tight linkage disequilibrium with another (P1842S). The mutants were found only at high frequency in one region and were accompanied by weak signatures of a selective sweep, with a significant decline between 2017 and 2023. Notably, kdr L976F was strongly associated with survivorship to exposure to DDT insecticide, while no clear association was noted with a pyrethroid insecticide (deltamethrin). The WHO prequalifies no DDT products for vector control, and the chemical is banned in Tanzania. Widespread DDT contamination and a legacy of extensive countrywide stockpiles may have selected for this mutation. Continued monitoring is necessary to understand the origin of kdr in An. funestus, and the threat posed to insecticide‐based vector control in Africa. [ABSTRACT FROM AUTHOR]

Mutations in voltage‐gated sodium (Nav) channels, which are essential for generating and propagating action potentials, can lead to serious neurological disorders, such as epilepsy. However, disease‐causing Nav channel mutations do not always result in severe symptoms, suggesting that the disease conditions are significantly affected by other genetic factors and various environmental exposures, collectively known as the "exposome". Notably, recent research emphasizes the pivotal role of commensal bacteria in neural development and function. Although these bacteria typically benefit the nervous system under normal conditions, their impact during pathological states remains largely unknown. Here, we investigated the influence of commensal microbes on seizure‐like phenotypes exhibited by paraShu—a gain‐of‐function mutant of the Drosophila Nav channel gene, paralytic. Remarkably, the elimination of endogenous bacteria considerably ameliorated neurological impairments in paraShu. Consistently, reintroducing bacteria, specifically from the Lactobacillus or Acetobacter genera, heightened the phenotypic severity in the bacteria‐deprived mutants. These findings posit that particular native bacteria contribute to the severity of seizure‐like phenotypes in paraShu. We further uncovered that treating paraShu with antibiotics boosted Nrf2 signaling in the gut, and that global Nrf2 activation mirrored the effects of removing bacteria from paraShu. This raises the possibility that the removal of commensal bacteria suppresses the seizure‐like manifestations through augmented antioxidant responses. Since bacterial removal during development was critical for suppression of adult paraShu phenotypes, our research sets the stage for subsequent studies, aiming to elucidate the interplay between commensal bacteria and the developing nervous system in conditions predisposed to the hyperexcitable nervous system. [ABSTRACT FROM AUTHOR]

BACKGROUND: Dermanyssus gallinae, the poultry red mite (PRM), is a worldwide ectoparasite posing significant economic challenges in poultry farming. The extensive use of pyrethroids for PRM control has led to the emergence of pyrethroid resistance. The objective of this study is to detect the pyrethroid resistance and explore its associated point mutations in the voltage‐gated sodium channel (VGSC) gene among PRM populations in China. RESULTS: Several populations of D. gallinae, namely CJF‐1, CJP‐2, CJP‐3, CSD‐4 and CLD‐5, displayed varying degrees of resistance to beta‐cypermethrin compared to a susceptible field population (CBP‐5). Mutations of VGSC gene in populations of PRMs associated with pyrethroid resistance were identified through sequencing its fragments IIS4–IIS5 and IIIS6. The mutations I917V, M918T/L, A924G and L925V were present in multiple populations, while no mutations were found at positions T929, I936, F1534 and F1538. CONCLUSION: The present study confirmed the presence of extremely high levels of pyrethroid resistance in PRM populations in China, and for the first time detected four pyrethroid resistance mutations in the VGSC gene. Identifying pyrethroid resistance in the field population of PRM in China can be achieved through screening for VGSC gene mutations as an early detection method. Our findings underscore the importance of implementing chemical PRM control strategies based on resistance evidence, while also considering the management of acaricide resistance in the control of PRMs. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Autism spectrum disorder (ASD) is a complex neurological and developmental disorder that affects how a person acts, communicates, learns, and interacts with others. It affects the structure and function of the brain and nervous system. How ASD is caused remains uncertain and there is no effective treatment for this disorder. Searching for new technologies for treatment of this disorder becomes a priority. Genetic alterations have been implicated in the generation of this disorder. One of the most promising genes for potential treatment of ASD is sodium voltage-gated channel alpha subunit 2 gene (SCN2A). SCN2A, encoding the neuronal voltage-gated Na+ channel NaV1.2, is one of the most commonly affected loci linked to ASD. Here, we discuss the implications of loss of function (LOF) mutations in SCN2A and the potential efficacy of gene therapy by highlighting the usage of CRISPR restoration of various Scn2a-insufficiencies. Various therapeutics exist that can be extrapolated to address the needs of Scn2a LOF induced ASD. The current treatment that exists for ASD can be seen as outdated in comparison to the advent of new technologies that build upon CRISPR. Due to complications in treatment of ASD, genetic therapies may induce alterations such as insertion–deletion mutations, which may lead to further complications along with a negative public outlook on CRISPR technologies. Gene therapy can be applied to ASD but much work is yet to be done in order to address both biochemical and ethical considerations.

Tetrodotoxin (TTX) is a potent neurotoxin firstly discovered in the ovary of pufferfish. The genetic basis of voltage-gated sodium channel resistance to TTX has been widely studied, but it remains unclear in the evolution history of voltage-gated sodium channel resistance to TTX in pufferfish with different TTX concentrations. In this study, six scn4aa coding sequences of pufferfish were firstly cloned and sequenced, then used to investigate the adaptive evolution of scn4aa associated with TTX concentration and reconstruct ancestral sequences with seven scn4aa of other fishes. The result of CODEML (codon substitution model) program from the PAML (phylogenetic analysis by maximum likelihood) package shows only in the genus of Takifugu, which contains TTX highly in the liver, under positive selection. The result also indicates that three of four positively selected sites are located in the intracellular regions, which may compensate for normal function. The ancestral sequence reconstruction may suggest that the replacements providing weak toxin resistance might have appeared first in scn4aa, then the genus Takifugu evolved stronger resistance to TTX later. These results contribute to the explanation of the evolutional history of voltage-gated sodium channel resistance to TTX in pufferfish.

This review focuses on the expression and function of voltage-gated sodium channel subtype NaV1.7 in various cancers and explores its impact on the metastasis driving cell functions such as proliferation, migration, and invasiveness. An overview of its structural characteristics, drug binding sites, inhibitors and their likely mechanisms of action are presented. Despite the lack of clarity on the precise mechanism by which NaV1.7 contributes to cancer progression and metastasis; many studies have suggested a connection between NaV1.7 and proteins involved in multiple signaling pathways such as PKA and EGF/EGFR-ERK1/2. Moreover, the functional activity of NaV1.7 appears to elevate the expression levels of MACC1 and NHE-1, which are controlled by p38 MAPK activity, HGF/c-MET signaling and c-Jun activity. This cascade potentially enhances the secretion of extracellular matrix proteases, such as MMPs which play critical roles in cell migration and invasion activities. Furthermore, the NaV1.7 activity may indirectly upregulate Rho GTPases Rac activity, which is critical for cytoskeleton reorganization, cell adhesion, and actin polymerization. The relationship between NaV1.7 and cancer progression has prompted researchers to investigate the therapeutic potential of targeting NaV1.7 using inhibitors. The positive outcome of such studies resulted in the discovery of several inhibitors with the ability to reduce cancer cell migration, invasion, and tumor growth underscoring the significance of NaV1.7 as a promising pharmacological target for attenuating cancer cell proliferation andmetastasis. The research findings summarized in this review suggest that the regulation of NaV1.7 expression and function by small molecules and/or by genetic engineering is a viable approach to discover novel therapeutics for the prevention and treatment of metastasis of cancerswith elevated NaV1.7 expression. [ABSTRACT FROM AUTHOR]

Background: Resistance to insecticides is one of the major problems in successfully controlling of mosquito-borne diseases. The present study explores the role of Voltage-Gated Sodium Channel (VGSC) and their mutation in the development of insecticide resistance in Anopheles mosquito. Materials and Methods: Homology protein modelling of wild-type and mutated VGSC protein was performed using the Swiss-Model server. Model proteins were analyzed using different bioinformatic tools, such as Procheck, Anolea, Errat, to study the overall quality. The binding affinity of insecticide permethrin with VGSC was analyzed using Autodock Tools software. Results and Discussion: The study observed that the model proteins have slight structural deviation between wild-type and mutant proteins. Model proteins docked with permethrin insecticide showed a higher binding affinity with wild-type than mutant channel protein. The present studies suggest that the point mutation in codon 1014 (Leucine→Cysteine) affects the complex stability, plausibly resisting the effect of the insecticide permethrin. Conclusion: The present study proposes the molecular interaction of permethrin with the ion channel leading to the development of insecticide resistance capacity in mosquito vectors. [ABSTRACT FROM AUTHOR]

ABSTRACTSexual dimorphism has been reported in multiple pre-clinical and clinical studies on pain. Previous investigations have suggested that in at least some states, rodent dorsal root ganglion (DRG) neurons display differential sex-dependent regulation and expression patterns of various proteins involved in the pain pathway. Our goal in this study was to determine whether sexual dimorphism in the biophysical properties of voltage-gated sodium (Nav) currents contributes to these observations in rodents. We recently developed a novel method that enables high-throughput, unbiased, and automated functional analysis of native rodent sensory neurons from naïve WT mice profiled simultaneously under uniform experimental conditions. In our previous study, we performed all experiments in neurons that were obtained from mixed populations of adult males or females, which were combined into single (combined male/female) data sets. Here, we have re-analyzed the same previously published data and segregated the cells based on sex. Although the number of cells in our previously published data sets were uneven for some comparisons, our results do not show sex-dependent differences in the biophysical properties of Nav currents in these native DRG neurons.

Pain is a major issue in healthcare throughout the world. It remains one of the major clinical issues of our time because it is a common sequela of numerous conditions, has a tremendous impact on individual quality of life, and is one of the top drivers of cost in medicine, due to its influence on healthcare expenditures and lost productivity in those affected by it. Patients and healthcare providers remain desperate to find new, safer and more effective analgesics. Growing evidence indicates that the voltage-gated sodium channel Nav1.8 plays a critical role in transmission of pain-related signals throughout the body. For that reason, this channel appears to have strong potential to help develop novel, more selective, safer, and efficacious analgesics. However, many questions related to the physiology, function, and clinical utility of Nav1.8 remain to be answered. In this article, we discuss the latest studies evaluating the role of Nav1.8 in pain, with a particular focus on visceral pain, as well as the steps taken thus far to evaluate its potential as an analgesic target. We also review the limitations of currently available studies related to this topic, and describe the next scientific steps that have already been undertaken, or that will need to be pursued, to fully unlock the capabilities of this potential therapeutic target. [ABSTRACT FROM AUTHOR]

Simple Summary: The tiger mosquito, Aedes albopictus, spreads the virus causing dengue fever, notably in Southeast Asian countries. To stop the spread of this disease, the Aedes mosquitoes are killed with chemicals known as pyrethroids. However, despite pyrethroids being highly effective insecticides, tiger mosquitoes are becoming resistant and surviving exposure to these chemicals. We have measured that tiger mosquitoes from two regions in Cambodia (the capital, Phnom Penh, and rural Pailin province) are highly resistant to pyrethroids. To determine what causes resistance, we have implicated unusually high activity of enzymes, known as P450 monooxygenases, which break down pyrethroids and thus render them harmless in the resistant mosquitoes. We have ruled out another common mechanism of pyrethroid resistance, which is changes in the mosquitoes' DNA sequence, which prevents pyrethroids from binding to a protein known as the voltage-gated sodium channel, thereby disrupting signals being sent throughout the nervous system. Overall, our findings describe an important survey monitoring the prevalence of insecticide resistance in disease-spreading mosquitoes in Cambodia, and with the increased understanding of what causes resistance, we are in a strong position to advise that mosquito control methods alternative to pyrethroids should be implemented as soon as possible to ensure continuing management of dengue fever. (1) Background: In Cambodia, Aedes albopictus is an important vector of the dengue virus. Vector control using insecticides is a major strategy implemented in managing mosquito-borne diseases. Resistance, however, threatens to undermine the use of insecticides. In this study, we present the levels of insecticide resistance of Ae. albopictus in Cambodia and the mechanisms involved. (2) Methods: Two Ae. albopictus populations were collected from the capital, Phnom Penh city, and from rural Pailin province. Adults were tested with diagnostic doses of malathion (0.8%), deltamethrin (0.03%), permethrin (0.25%), and DDT (4%) using WHO tube assays. Synergist assays using piperonyl butoxide (PBO) were implemented before the pyrethroid assays to detect the potential involvement of metabolic resistance mechanisms. Adult female mosquitoes collected from Phnom Penh and Pailin were tested for voltage-gated sodium channel (VGSC) kdr (knockdown resistance) mutations commonly found in Aedes sp.-resistant populations throughout Asia (S989P, V1016G, and F1534C), as well as for other mutations (V410L, L982W, A1007G, I1011M, T1520I, and D1763Y). (3) Results: The two populations showed resistance against all the insecticides tested (<90% mortality). The use of PBO (an inhibitor of P450s) strongly restored the efficacy of deltamethrin and permethrin against the two resistant populations. Sequences of regions of the vgsc gene showed a lack of kdr mutations known to be associated with pyrethroid resistance. However, four novel non-synonymous mutations (L412P/S, C983S, Q1554STOP, and R1718L) and twenty-nine synonymous mutations were detected. It remains to be determined whether these mutations contribute to pyrethroid resistance. (4) Conclusions: Pyrethroid resistance is occurring in two Ae. albopictus populations originating from urban and rural areas of Cambodia. The resistance is likely due to metabolic resistance specifically involving P450s monooxygenases. The levels of resistance against different insecticide classes are a cause for concern in Cambodia. Alternative tools and insecticides for controlling dengue vectors should be used to minimize disease prevalence in the country. [ABSTRACT FROM AUTHOR]

There is increasing evidence, mostly from breast cancer, that use of local anaesthetics during surgery can inhibit disease recurrence by suppressing the motility of the cancer cells dependent on inherent voltage-gated sodium channels (VGSCs). Here, the possibility that lidocaine could affect cellular behaviours associated with metastasis was tested using the Dunning cell model of rat prostate cancer. Mostly, the strongly metastatic (VGSC-expressing) Mat-LyLu cells were used under both normoxic and hypoxic conditions. The weakly metastatic AT-2 cells served for comparison in some experiments. Lidocaine (1–500 μM) had no effect on cell viability or growth but suppressed Matrigel invasion dose dependently in both normoxia and hypoxia. Used as a control, tetrodotoxin produced similar effects. Exposure to hypoxia increased Nav1.7 mRNA expression but VGSCα protein level in plasma membrane was reduced. Lidocaine under both normoxia and hypoxia had no effect on Nav1.7 mRNA expression. VGSCα protein expression was suppressed by lidocaine under normoxia but no effect was seen in hypoxia. It is concluded that lidocaine can suppress prostate cancer invasiveness without effecting cellular growth or viability. Extended to the clinic, the results would suggest that use of lidocaine, and possibly other local anaesthetics, during surgery can suppress any tendency for post-operative progression of prostate cancer. [ABSTRACT FROM AUTHOR]

This review focuses on the expression and function of voltage-gated sodium channel subtype NaV1.7 in various cancers and explores its impact on the metastasis driving cell functions such as proliferation, migration, and invasiveness. An overview of its structural characteristics, drug binding sites, inhibitors and their likely mechanisms of action are presented. Despite the lack of clarity on the precise mechanism by which NaV1.7 contributes to cancer progression and metastasis; many studies have suggested a connection between NaV1.7 and proteins involved in multiple signaling pathways such as PKA and EGF/EGFR-ERK1/2. Moreover, the functional activity of NaV1.7 appears to elevate the expression levels of MACC1 and NHE-1, which are controlled by p38 MAPK activity, HGF/c-MET signaling and c-Jun activity. This cascade potentially enhances the secretion of extracellular matrix proteases, such as MMPs which play critical roles in cell migration and invasion activities. Furthermore, the NaV1.7 activity may indirectly upregulate Rho GTPases Rac activity, which is critical for cytoskeleton reorganization, cell adhesion, and actin polymerization. The relationship between NaV1.7 and cancer progression has prompted researchers to investigate the therapeutic potential of targeting NaV1.7 using inhibitors. The positive outcome of such studies resulted in the discovery of several inhibitors with the ability to reduce cancer cell migration, invasion, and tumor growth underscoring the significance of NaV1.7 as a promising pharmacological target for attenuating cancer cell proliferation and metastasis. The research findings summarized in this review suggest that the regulation of NaV1.7 expression and function by small molecules and/or by genetic engineering is a viable approach to discover novel therapeutics for the prevention and treatment of metastasis of cancers with elevated NaV1.7 expression.

Ke Ma,1,&ast; Zhixiang Cheng,2,&ast; Hao Jiang,3,&ast; Zhangya Lin,4,&ast; Chuansheng Liu,5,&ast; Xianguo Liu,6,&ast; Lijuan Lu,7,&ast; Yan Lu,8,&ast; Wei Tao,9,&ast; Suoliang Wang,10,&ast; Xiaoqiu Yang,11,&ast; Qishan Yi,12,&ast; Xiaomei Zhang,13,&ast; Ying Zhang,14,&ast; Yanqing Liu15,&ast; 1Department of Algology, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, People’s Republic of China; 2Department of Algology, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, People’s Republic of China; 3Department of Algology, The First Affiliated Hospital of Fujian Medical University, Fuzhou, People’s Republic of China; 4Department of Neurosurgery, The First Affiliated Hospital of Fujian Medical University, Fuzhou, People’s Republic of China; 5Department of Algology, The Affiliated Hospital of Qingdao University, Qingdao, People’s Republic of China; 6Pain Research Center, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, People’s Republic of China; 7Department of Pain Medicine, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing, People’s Republic of China; 8Department of Algology, Xijing Hospital, The Fourth Military Medical University, Xian, People’s Republic of China; 9Department of Neurosurgery, Shenzhen University General Hospital, Shenzhen, People’s Republic of China; 10Department of Algology, The First Affiliated Hospital, Xi’an Jiaotong University, Xi’an, People’s Republic of China; 11Department of Algology, The First Affiliated Hospital of Chongqing Medical University, Chongqing, People’s Republic of China; 12Department of Algology, The Yibin First People’s Hospital Affiliated Chongqing Medical University, Yibin, People’s Republic of China; 13Department of Algology, The First Affiliated Hospital of Kunming Medical University, Kunming, People’s Republic of China; 14Department of Algology. Hospital (T.C.M) Affiliated to Southwest Medical University, Luzhou, People’s Republic of China; 15Department of Algology, Beijing Tiantan Hospital, Capital Medical University, Beijing, People’s Republic of China&ast;These authors contributed equally to this workCorrespondence: Ke Ma, Department of Algology, Xinhua Hospital Affiliated to Shanghai Jiao Tong University school of medicine, Shanghai, 200092, People’s Republic of China, Tel +86133618792160, Email marke72@163.com Yanqing Liu, Department of Algology, Beijing Tiantan Hospital, Capital Medical University, Beijing, 100070, People’s Republic of China, Tel +8618601203409, Email lyqttyy@126.comAbstract: Ion channel drugs have been increasing used for chronic pain management with progress in the development of selective calcium channel modulators. Although ion channel drugs have been proven safe and effective in clinical practice, uncertainty remains regarding its use to treat chronic pain. To standardize the clinical practice of ion channel drug for the treatment of chronic pain, the National Health Commission Capacity Building and Continuing Education Center for Pain Diagnosis and Treatment Special Ability Training Project established an expert group to form an expert consensus on the use of ion channel drugs for the treatment of chronic pain after repeated discussions on existing medical evidence combined with the well clinical experience of experts. The consensus provided information on the mechanism of action of ion channel drugs and their recommendations, caution use, contraindications, and precautions for their use in special populations to support doctors in their clinical decision-making.Keywords: chronic pain, ion channel drugs, voltage-gated calcium channels, voltage-gated sodium channel

The most promising anticonvulsant phytocompounds were explored in this work using docking, molecular dynamic (MD) simulation, and Molecular Mechanics-Poisson–Boltzmann Surface Area (MM-PBSA) approaches. A total of 70 phytochemicals were screened against α-amino-3-hydroxyl-5-methyl-4-isoxazole propionic acid (AMPA), N-methyl-d-aspartate (NMDA), voltage-gated sodium ion channels (VGSC), and carbonic anhydrase enzyme II (CA II) receptors, and the docking results were compared to the reference drug phenytoin. Amentoflavone displayed the highest affinity for AMPA and VGSC receptors, with docking scores of − 10.4 and − 10.1 kcal/mol, respectively. Oliganthin H-NMDA and epigallocatechin-3-gallate-CA II complexes showed docking scores of − 10.9 and − 6.9 kcal/mol, respectively. All four complexes depicted a high dock score compared to the phenytoin complex at the binding site of the corresponding proteins. The MD simulation investigated the stabilities and favorable conformation of apoproteins and ligand/reference-bound complexes. The results revealed that proteins AMPA, VGSC, and CA II were more efficiently stabilized by lead phytochemicals than phenytoin binding. Additionally, principal component analysis and MM-PBSA results suggested that these lead phytocompounds have good compactness and strong binding free energy. Further, physicochemical and pharmacokinetic studies revealed that these final lead phytochemicals would be suitable for oral intake, have sufficient intestinal permeability, and have the ability to cross the blood–brain barrier (BBB). Comprehensively, this study predicted amentoflavone as the best lead phytochemical out of the 70 anticonvulsant phytocompounds that can be used to treat epilepsy. [ABSTRACT FROM AUTHOR]

In order to investigate the tetrodotoxin（TTX） content in the tissues of Takifugu obscurus and the expression characteristics of voltage gated sodium channel genes in toxic tissues, this study used enzymelinked immunosorbent assay（ ELISA） to determine the TTX content in 8 tissues, including the liver and heart of Takifugu obscurus. Real time fluorescence quantification （RT-qPCR） was used to detect the relative expression of voltage gated sodium channels α subunit gene family, including scn1aa, scn1ab, scn4aa, scn4ab, scn5aa, scn5ab, scn8aa, and scn8ab in various tissues. The results showed that the TTX content in various tissues ranged from high to low, including brain （9. 521 ± 2. 816） μg/g, heart （4. 271 ± 1. 129） μg/g, gills（ 1. 586 ± 0. 527） μg/g, muscle（ 1. 494 ± 0. 938） μg/g, liver（ 0. 913 ± 0. 206） μg/g, skin（ 0. 902 ± 0. 235） μg/g, intestine （0. 894 ± 0. 215） μg/g, and eye （0. 864 ± 0. 287） μg/g. Brain and heart tissues were weakly toxic, while liver, skin, muscle, eye, intestine, and gill tissues were slightly toxic. The RTqPCR results showed that the relative expression levels of scn1aa, scn1ab, scn4ab, scn5aa, scn5ab, scn8aa, and scn8ab genes were the highest in liver tissue. The scn4aa gene was only expressed in muscle tissue, and only the scn4ab gene was expressed in skin tissue. Moreover, the scn4ab gene was expressed in all detected tissue types, indicating widespread expression. It is discovered that there are differences in the expression characteristics of sodium channel genes between zebrafish and Takifugu obscurus tissues. [ABSTRACT FROM AUTHOR]

Voltage-gated sodium channels (Nav) undergo conformational shifts in response to membrane potential changes, a mechanism known as the electromechanical coupling. To delineate the structure-function relationship of human Nav channels, we have performed systematic structural analysis using human Nav1.7 as a prototype. Guided by the structural differences between wild-type (WT) Nav1.7 and an eleven mutation-containing variant, designated Nav1.7-M11, we generated three additional intermediate mutants and solved their structures at overall resolutions of 2.9-3.4 Å. The mutant with nine-point mutations in the pore domain (PD), named Nav1.7-M9, has a reduced cavity volume and a sealed gate, with all voltage-sensing domains (VSDs) remaining up. Structural comparison of WT and Nav1.7-M9 pinpoints two residues that may be critical to the tightening of the PD. However, the variant containing these two mutations, Nav1.7-M2, or even in combination with two additional mutations in the VSDs, named Nav1.7-M4, failed to tighten the PD. Our structural analysis reveals a tendency of PD contraction correlated with the right shift of the static inactivation I-V curves. We predict that the channel in the resting state should have a "tight" PD with down VSDs. [ABSTRACT FROM AUTHOR]

Purpose: Guanfacine is an α2A-adrenergic receptor agonist, FDA-approved to treat attention-deficit hyperactivity disorder and high blood pressure, typically as an extended-release formulation up to 7 mg/day. In our dysautonomia clinic, we observed that off-label use of short-acting guanfacine at 1 mg/day facilitated symptom relief in two families with multiple members presenting with severe generalized anxiety. We also noted anecdotal improvements in associated dysautonomia symptoms such as hyperhidrosis, cognitive impairment, and palpitations. We postulated that a genetic deficit existed in these patients that might augment guanfacine susceptibility. Methods: We used whole-exome sequencing to identify mutations in patients with shared generalized anxiety and dysautonomia symptoms. Guanfacine-induced changes in the function of voltage-gated Na+ channels were investigated using voltage-clamp electrophysiology. Results: Whole-exome sequencing uncovered the p.I739V mutation in SCN9A in the proband of two nonrelated families. Moreover, guanfacine inhibited ionic currents evoked by wild-type and mutant NaV1.7 encoded by SCN9A, as well as other NaV channel subtypes to a varying degree. Conclusion: Our study provides further evidence for a possible pathophysiological role of NaV1.7 in anxiety and dysautonomia. Combined with off-target effects on NaV channel function, daily administration of 1 mg short-acting guanfacine may be sufficient to normalize NaV channel mutation-induced changes in sympathetic activity, perhaps aided by partial inhibition of NaV1.7 or other channel subtypes. In a broader context, expanding genetic and functional data about ion channel aberrations may enable the prospect of stratifying patients in which mutation-induced increased sympathetic tone normalization by guanfacine can support treatment strategies for anxiety and dysautonomia symptoms. [ABSTRACT FROM AUTHOR]

BACKGROUND: The larvae of Drosophila suzukii Matsumura feed directly inside the fruit, causing catastrophic damage to orchards. The misuse of pyrethroid insecticides during the control period has led to increasing resistance of D. suzukii to pyrethroids acting on the voltage‐gated sodium channel (VGSC). RESULTS: In this study, the sodium channel of D. suzukii was cloned (DsNav5 GenBank number: OQ871532). The results of multiple‐sequence alignment showed that the homology of sodium channel between D. suzukii and Drosophila melanogaster was as high as 95.3%. Analysis of transcripts from 62 variants of D. suzukii VGSC revealed a total of six alternative splicing sites (exons u, j, a, b, e, and h) and 33 RNA editing. Exons j, a, b, e, and h are conserved in D. melanogaster and other insects, whereas exon u has never been reported before. The number of A‐to‐I was distinctly more than that of U‐to‐C for RNA editing. All D. suzukii VGSC variants were expressed in Xenopus oocytes, but only one (type 5) was able to produce robust currents and nine produce weak currents. DsNav5 with TipE of D. melanogaster co‐expresses current better than its own TipE. Subsequently, tetrodotoxin was verified to be a blocker of VGSC, and the gating properties of DsNav5 were investigated. CONCLUSION: These findings proved that the VGSC of D. suzukii has not only the basic gating properties, but also the diversity of gating properties. This study also laid a foundation for the study of pyrethroid resistance mechanism of VGSC in D. suzukii. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Pain is a major issue in healthcare throughout the world. It remains one of the major clinical issues of our time because it is a common sequela of numerous conditions, has a tremendous impact on individual quality of life, and is one of the top drivers of cost in medicine, due to its influence on healthcare expenditures and lost productivity in those affected by it. Patients and healthcare providers remain desperate to find new, safer and more effective analgesics. Growing evidence indicates that the voltage-gated sodium channel Nav1.8 plays a critical role in transmission of pain-related signals throughout the body. For that reason, this channel appears to have strong potential to help develop novel, more selective, safer, and efficacious analgesics. However, many questions related to the physiology, function, and clinical utility of Nav1.8 remain to be answered. In this article, we discuss the latest studies evaluating the role of Nav1.8 in pain, with a particular focus on visceral pain, as well as the steps taken thus far to evaluate its potential as an analgesic target. We also review the limitations of currently available studies related to this topic, and describe the next scientific steps that have already been undertaken, or that will need to be pursued, to fully unlock the capabilities of this potential therapeutic target.

Abstract Background Since 2014, dengue epidemics have occurred almost annually in Nouakchott, the capital city of Mauritania, coinciding with the recent establishment of Aedes aegypti, the primary vector of dengue, in the city. Anopheles arabiensis, the primary vector of malaria, is also abundant not only in Nouakchott but also in most areas of the country. Resistance to insecticides has been studied in An. arabiensis but not in Ae. aegypti in Mauritania. The objective of the present study was to establish the baseline data on the frequencies of knockdown resistance (kdr) mutations in the voltage-gated sodium channel (vgsc) gene in Ae. aegypti collected in Nouakchott to improve vector control. Methods Resting Ae. aegypti mosquitoes were collected in 2017 and 2018 in Teyarett and Dar Naim districts in Nouakchott using a battery-powered aspirator. Polymerase chain reaction (PCR) and DNA sequencing were performed to detect the presence of five kdr mutations known to be associated with pyrethroid resistance: L982W, S989P, I1011M/G, V1016G/I, and F1534C. Results A total of 100 female Ae. aegypti mosquitoes were identified among collected resting culicid fauna, of which 60% (60/100) were unfed, 12% (12/100) freshly blood-fed, and 28% (28/100) gravid. Among the mutations investigated in this study, 989P, 1016G, and 1534C were found to be widespread, with the frequencies of 0.43, 0.44, and 0.55, respectively. Mutations were not found in codons 982 and 1011. No other mutations were detected within the fragments analyzed in this study. Genotype distribution did not deviate from Hardy–Weinberg equilibrium. The most frequent co-occurring point mutation patterns among Ae. aegypti mosquitoes were the heterozygous individuals 989SP/1016VG/1534FC detected in 45.1% of mosquitoes. In addition, homozygous mutant 1534CC co-occurred simultaneously with homozygous wild type 989SS and 1016VV in 30.5% of mosquito specimens. Inversely, homozygous wild-type 1534FF co-occurred simultaneously with homozygous mutant 989PP and 1016GG in 19.5% of the mosquitoes. Conclusions To our knowledge, this is the first study reporting the presence of three point mutations in the vgsc gene of Ae. aegypti in Mauritania. The findings of the present study are alarming because they predict a high level of resistance to pyrethroid insecticides which are commonly used in vector control in the country. Therefore, further studies are urgently needed, in particular phenotypic characterization of insecticide resistance using the standardized test. Graphical Abstract

The voltage-gated sodium channel (NaV), NaV1.1, is well-studied in the central nervous system; conversely, its contribution to peripheral sensory neuron function is more enigmatic. Here, we identify a new role for NaV1.1 in mammalian proprioception. RNAscope analysis and in vitro patch-clamp recordings in genetically identified mouse proprioceptors show ubiquitous channel expression and significant contributions to intrinsic excitability. Notably, genetic deletion of NaV1.1 in sensory neurons caused profound and visible motor coordination deficits in conditional knockout mice of both sexes, similar to conditional Piezo2-knockout animals, suggesting that this channel is a major contributor to sensory proprioceptive transmission. Ex vivo muscle afferent recordings from conditional knockout mice found that loss of NaV1.1 leads to inconsistent and unreliable proprioceptor firing characterized by action potential failures during static muscle stretch; conversely, afferent responses to dynamic vibrations were unaffected. This suggests that while a combination of Piezo2 and other NaV isoforms is sufficient to elicit activity in response to transient stimuli, NaV1.1 is required for transmission of receptor potentials generated during sustained muscle stretch. Impressively, recordings from afferents of heterozygous conditional knockout animals were similarly impaired, and heterozygous conditional knockout mice also exhibited motor behavioral deficits. Thus, NaV1.1 haploinsufficiency in sensory neurons impairs both proprioceptor function and motor behaviors. Importantly, human patients harboring NaV1.1 loss-of-function mutations often present with motor delays and ataxia; therefore, our data suggest that sensory neuron dysfunction contributes to the clinical manifestations of neurological disorders in which NaV1.1 function is compromised. Collectively, we present the first evidence that NaV1.1 is essential for mammalian proprioceptive signaling and behaviors.

Voltage-gated sodium channel NaV1.8 regulates transmission of pain signals to the brain. While NaV1.8 has the potential to serve as a drug target, the molecular mechanisms that shape NaV1.8 gating are not completely understood, particularly mechanisms that couple activation to inactivation. Interactions between toxin producing animals and their predators provide a novel approach for investigating NaV structure-function relationships. Arizona bark scorpions produce Na+ channel toxins that initiate pain signaling. However, in predatory grasshopper mice, toxins inhibit NaV1.8 currents and block pain signals. A screen of synthetic peptide toxins predicted from bark scorpion venom showed that peptide NaTx36 inhibited Na+ current recorded from a recombinant grasshopper mouse NaV1.8 channel (OtNaV1.8). Toxin NaTx36 hyperpolarized OtNaV1.8 activation, steady-state fast inactivation, and slow inactivation. Mutagenesis revealed that the first gating charge in the domain I (DI) S4 voltage sensor and an acidic amino acid (E) in the DII SS2 - S6 pore loop are critical for the inhibitory effects of NaTx36. Computational modeling showed that a DI S1 - S2 asparagine (N) stabilizes the NaTx36 - OtNaV1.8 complex while residues in the DI S3 - S4 linker and S4 voltage sensor form electrostatic interactions that allow a toxin glutamine (Q) to contact the first S4 gating charge. Surprisingly, the models predicted that NaTx36 contacts amino acids in the DII S5 - SS1 pore loop instead of the SS2 - S6 loop; the DII SS2 - S6 loop motif (QVSE) alters the conformation of the DII S5 - SS1 pore loop, enhancing allosteric interactions between toxin and the DII S5 - SS1 pore loop. Few toxins have been identified that modify NaV1.8 gating. Moreover, few toxins have been described that modify sodium channel gating via the DI S4 voltage sensor. Thus, NaTx36 and OtNaV1.8 provide tools for investigating the structure-activity relationship between channel activation and inactivation gating, and the connection to alternative pain phenotypes.

BackgroundGenetic variants in the voltage-gated sodium channels SCN1A, SCN2A, SCN3A, and SCN8A are leading causes of epilepsy, developmental delay, and autism spectrum disorder. The mRNA splicing patterns of all four genes vary across development in the rodent brain, including mutually exclusive copies of the fifth protein-coding exon detected in the neonate (5N) and adult (5A). A second pair of mutually exclusive exons is reported in SCN8A only (18N and 18A). We aimed to quantify the expression of individual exons in the developing human brain.MethodsRNA-seq data from 783 human brain samples across development were analyzed to estimate exon-level expression. Developmental changes in exon utilization were validated by assessing intron splicing. Exon expression was also estimated in RNA-seq data from 58 developing mouse neocortical samples.ResultsIn the mature human neocortex, exon 5A is consistently expressed at least 4-fold higher than exon 5N in all four genes. For SCN2A, SCN3A, and SCN8A, a brain-wide synchronized 5N to 5A transition occurs between 24 post-conceptual weeks (2nd trimester) and 6 years of age. In mice, the equivalent 5N to 5A transition begins at or before embryonic day 15.5. In SCN8A, over 90% of transcripts in the mature human cortex include exon 18A. Early in fetal development, most transcripts include 18N or skip both 18N and 18A, with a transition to 18A inclusion occurring from 13 post-conceptual weeks to 6 months of age. No other protein-coding exons showed comparably dynamic developmental trajectories.ConclusionsExon usage in SCN1A, SCN2A, SCN3A, and SCN8A changes dramatically during human brain development. These splice isoforms, which alter the biophysical properties of the encoded channels, may account for some of the observed phenotypic differences across development and between specific variants. Manipulation of the proportion of splicing isoforms at appropriate stages of development may act as a therapeutic strategy for specific mutations or even epilepsy in general.

Background: Since 2014, dengue epidemics have occurred almost annually in Nouakchott, the capital city of Mauritania, coinciding with the recent establishment of Aedes aegypti, the primary vector of dengue, in the city. Anopheles arabiensis, the primary vector of malaria, is also abundant not only in Nouakchott but also in most areas of the country. Resistance to insecticides has been studied in An. arabiensis but not in Ae. aegypti in Mauritania. The objective of the present study was to establish the baseline data on the frequencies of knockdown resistance (kdr) mutations in the voltage-gated sodium channel (vgsc) gene in Ae. aegypti collected in Nouakchott to improve vector control. Methods: Resting Ae. aegypti mosquitoes were collected in 2017 and 2018 in Teyarett and Dar Naim districts in Nouakchott using a battery-powered aspirator. Polymerase chain reaction (PCR) and DNA sequencing were performed to detect the presence of five kdr mutations known to be associated with pyrethroid resistance: L982W, S989P, I1011M/G, V1016G/I, and F1534C. Results: A total of 100 female Ae. aegypti mosquitoes were identified among collected resting culicid fauna, of which 60% (60/100) were unfed, 12% (12/100) freshly blood-fed, and 28% (28/100) gravid. Among the mutations investigated in this study, 989P, 1016G, and 1534C were found to be widespread, with the frequencies of 0.43, 0.44, and 0.55, respectively. Mutations were not found in codons 982 and 1011. No other mutations were detected within the fragments analyzed in this study. Genotype distribution did not deviate from Hardy–Weinberg equilibrium. The most frequent co-occurring point mutation patterns among Ae. aegypti mosquitoes were the heterozygous individuals 989SP/1016VG/1534FC detected in 45.1% of mosquitoes. In addition, homozygous mutant 1534CC co-occurred simultaneously with homozygous wild type 989SS and 1016VV in 30.5% of mosquito specimens. Inversely, homozygous wild-type 1534FF co-occurred simultaneously with homozygous mutant 989PP and 1016GG in 19.5% of the mosquitoes. Conclusions: To our knowledge, this is the first study reporting the presence of three point mutations in the vgsc gene of Ae. aegypti in Mauritania. The findings of the present study are alarming because they predict a high level of resistance to pyrethroid insecticides which are commonly used in vector control in the country. Therefore, further studies are urgently needed, in particular phenotypic characterization of insecticide resistance using the standardized test. [ABSTRACT FROM AUTHOR]

Brugada Syndrome (BrS) is a genetic heart condition linked to sudden cardiac death. Though the SCN5A gene is primarily associated with BrS, there is a lack of comprehensive studies exploring the connection between SCN5A mutation locations and the clinical presentations of the syndrome. This study aimed to address this gap and gain further understanding of the syndrome. The investigation classified 36 high-risk BrS patients based on SCN5A mutations within the transmembrane/structured (TD) and intra-domain loops (IDLs) lacking a 3D structure. We characterized the intrinsically disordered regions (IDRs) abundant in IDLs, using bioinformatics tools to predict IDRs and post-translational modifications (PTMs) in NaV1.5. Interestingly, it was found that current predictive tools often underestimate the impacts of mutations in IDLs and disordered regions. Moreover, patients with SCN5A mutations confined to IDL regions—previously deemed 'benign'—displayed clinical symptoms similar to those carrying 'damaging' variants. Our research illuminates the difficulty in stratifying patients based on SCN5A mutation locations, emphasizing the vital role of IDLs in the NaV1.5 channel's functioning and protein interactions. We advocate for caution when using predictive tools for mutation evaluation in these regions and call for the development of improved strategies in accurately assessing BrS risk [ABSTRACT FROM AUTHOR]

The voltage-gated sodium channel (Nav) is widely present in mammals and can generate cell action potentials, which are related to many diseases. The μ-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 Nav channel subtypes. In this study, the effects of eight μ-CTx on different Nav channel isoforms were reviewed, and sequence alignment and protein homologous modeling were used to predict their biological activities, and the structure-activity relationship between μ-CTx and mutagenesis strategies. [ABSTRACT FROM AUTHOR]

Voltage-gated sodium (NaV) channels are transmembrane proteins that play a critical role in electrical signaling in the nervous system and other excitable tissues. µ-Conotoxins are peptide toxins from the venoms of marine cone snails (genus Conus) that block NaV channels with nanomolar potency. Most species of the subgenera Textilia and Afonsoconus are difficult to acquire; therefore, their venoms have yet to be comprehensively interrogated for µ-conotoxins. The goal of this study was to find new µ-conotoxins from species of the subgenera Textilia and Afonsoconus and investigate their selectivity at human NaV channels. Using RNA-seq of the venom gland of Conus (Textilia) bullatus, we identified 12 µ-conotoxin (or µ-conotoxin-like) sequences. Based on these sequences we designed primers which we used to identify additional µ-conotoxin sequences from DNA extracted from historical specimens of species from Textilia and Afonsoconus. We synthesized six of these µ-conotoxins and tested their activity on human NaV1.1–NaV1.8. Five of the six synthetic peptides were potent blockers of human NaV channels. Of these, two peptides (BuIIIB and BuIIIE) were potent blockers of hNaV1.3. Three of the peptides (BuIIIB, BuIIIE and AdIIIA) had submicromolar activity at hNaV1.7. This study serves as an example of the identification of new peptide toxins from historical DNA and provides new insights into structure–activity relationships of µ-conotoxins with activity at hNaV1.3 and hNaV1.7. [ABSTRACT FROM AUTHOR]

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BACKGROUND: Transcranial magneto-acousto-electrical stimulation (TMAES) is a new non-invasive neuromodulation technique, which uses the induced field generated by the coupling of ultrasound and static magnetic fields to regulate the firing activity of the nervous system, but the mechanism of its neuromodulatory effect is not yet clear. OBJECTIVE: To explore the intrinsic mediating mechanism of TMAES regulating the changes of neural excitability in aged mice. METHODS: Twenty aged mice were equally and randomly divided into aged control group (receiving pseudo-stimulation), magnetic field group (receiving 0.3 T static magnetic field stimulation), ultrasound group (receiving 2.6 W/cm2 ultrasound stimulation), and magneto-acoustical group (receiving 0.3 T and 2.6 W/cm2 coupling stimulation), with five mice in each group. Simulation in each group was done 2 minutes per day for 14 continuous days. Another five young mice (2 months of age) served as the young group (receiving pseudo-stimulation). Then, patch-clamp technique was used to record the ionic currents of relevant channels during cell activation, inactivation, and reactivation in brain slices of mice. RESULTS AND CONCLUSION: Compared with the aged control group, TMAES significantly increased the current peak value of sodium channels (P < 0.05), shifted the activation curve of voltage-gated sodium channel currents to the left, shifted the inactivation curve to the right, and shortened the reactivation time (P < 0.05). However, there was a significant difference between magneto-acoustical and young groups (P < 0.05). Compared with the aged control group, TMAES suppressed the current peaks of potassium channels, shifted the activation curves of both transient outward potassium currents and delayed rectifier potassium currents to the right, shifted the inactivation curves of transient outward potassium currents to the left, and extended the reactivation time of transient outward potassium currents. However, there was still a significant difference between magneto-acoustical and young groups (P < 0.05). All these findings indicate that TMAES can activate sodium currents and inhibit potassium currents through altering the dynamic characteristics of relevant ion channels, thereby improving the neural excitability of aged mice, but not up to the level of young mice. This neuromodulation technique is expected to provide potential possibilities for delaying aging. Key words: transcranial magnet [ABSTRACT FROM AUTHOR]

Scorpion α‐toxins (α‐NaTx) inhibiting the inactivation of voltage‐gated sodium channels (Nav) are a well‐studied family of small proteins. We previously showed that the structure of α‐NaTx specificity module responsible for selective Nav binding is governed by an interplay between the nest and niche protein motifs. Here, we report the solution structure of the toxin Lqq4 from the venom of the scorpion Leiurus quinquestriatus. Unexpectedly, we find that this toxin presents an ensemble of long‐lived structurally distinct states. We unequivocally assign these states to the alternative configurations (cis–trans isomers) of two peptide bonds: V56–P57 and C17–G18; neither of the cis isomers has been described in α‐NaTx so far. We argue that the native conformational space of α‐NaTx is wider than assumed previously. [ABSTRACT FROM AUTHOR]

The voltage-gated sodium channel subtype Nav1.6 is involved in the electrophysiological changes of primary sensory neurons that occur in oxaliplatin-induced neuropathic pain, but its regulatory mechanism remains unclear. In this study, Western blot, RT-qPCR, immunofluorescence staining, chromatin immunoprecipitation were used to prove the mechanism of MAPK-ERK-CREB signaling pathway participating in oxaliplatin-induced neuropathic pain by regulating Nav1.6. The results showed that p-Raf1 and p-ERK, key molecules in MAPK/ERK pathway, and Nav1.6 were significantly increased in DRGs of oxaliplatin-induced neuropathic pain rats. Inhibition of p-Raf1 and p-ERK respectively not only reduced the expression of Nav1.6 protein in DRGs of OXA rats, but also caused a decrease in Nav1.6 mRNA, which led us to further explore the transcription factor CREB regulated by MAPK/ERK pathway. Results showed that CREB was co-distributed with Nav1.6. Inhibition of CREB resulted in decreased mRNA and protein expression of Nav1.6, and alleviated oxaliplatin-induced neuropathic pain. A chromatin immunoprecipitation experiment proved that OXA caused p-CREB to directly bind to the promoter region of Scn8A, which is the encoding gene for Nav1.6, and promote the transcription of Scn8A. In summary, in this study, we found that oxaliplatin can activate the MAPK/ERK pathway, which promotes the expression and activation of CREB and leads to an increase in Scn8A transcription, and then leads to an increase in Nav1.6 protein expression to enhance neuronal excitability and cause pain. This study provides an experimental basis for the molecular mechanism of sodium channel regulation in oxaliplatin-induced neuropathic pain. [Display omitted] • The MAPK-ERK-CREB signaling pathway is activated in the DRGs of rats with oxaliplatin-induced neuropathologic pain. • The MAPK-ERK pathway transcriptionally regulates Nav1.6 through activation of CREB in oxaliplatin-induced neuropathic pain. • p-CREB promotes transcription by binding to the Scn8A promoter region, which ultimately leads to increased Nav1.6 protein expression. [ABSTRACT FROM AUTHOR]

Venom‐derived peptides targeting ion channels involved in pain are regarded as a promising alternative to current, and often ineffective, chronic pain treatments. Many peptide toxins are known to specifically and potently block established therapeutic targets, among which the voltage‐gated sodium and calcium channels are major contributors. Here, we report on the discovery and characterization of a novel spider toxin isolated from the crude venom of Pterinochilus murinus that shows inhibitory activity at both hNaV1.7 and hCaV3.2 channels, two therapeutic targets implicated in pain pathways. Bioassay‐guided HPLC fractionation revealed a 36‐amino acid peptide with three disulfide bridges named μ/ω‐theraphotoxin‐Pmu1a (Pmu1a). Following isolation and characterization, the toxin was chemically synthesized and its biological activity was further assessed using electrophysiology, revealing Pmu1a to be a toxin that potently blocks both hNaV1.7 and hCaV3. Nuclear magnetic resonance structure determination of Pmu1a shows an inhibitor cystine knot fold that is the characteristic of many spider peptides. Combined, these data show the potential of Pmu1a as a basis for the design of compounds with dual activity at the therapeutically relevant hCaV3.2 and hNaV1.7 voltage‐gated channels. [ABSTRACT FROM AUTHOR]

Diseases spread by mosquitoes lead to the death of 700,000 people each year. The main way to reduce transmission is vector control by biting prevention with chemicals. However, the most commonly used insecticides lose efficacy due to the growing resistance. Voltage-gated sodium channels (VGSCs), membrane proteins responsible for the depolarizing phase of an action potential, are targeted by a broad range of neurotoxins, including pyrethroids and sodium channel blocker insecticides (SCBIs). Reduced sensitivity of the target protein due to the point mutations threatened malaria control with pyrethroids. Although SCBIs—indoxacarb (a pre-insecticide bioactivated to DCJW in insects) and metaflumizone—are used in agriculture only, they emerge as promising candidates in mosquito control. Therefore, a thorough understanding of molecular mechanisms of SCBIs action is urgently needed to break the resistance and stop disease transmission. In this study, by performing an extensive combination of equilibrium and enhanced sampling molecular dynamics simulations (3.2 μs in total), we found the DIII-DIV fenestration to be the most probable entry route of DCJW to the central cavity of mosquito VGSC. Our study revealed that F1852 is crucial in limiting SCBI access to their binding site. Our results explain the role of the F1852T mutation found in resistant insects and the increased toxicity of DCJW compared to its bulkier parent compound, indoxacarb. We also delineated residues that contribute to both SCBIs and non-ester pyrethroid etofenprox binding and thus could be involved in the target site cross-resistance. [ABSTRACT FROM AUTHOR]

• Feeding Drosophila mutants a small amount of milk lipids can suppress seizures. • Part of the seizure-suppressing effects of milk lipids is due to α-linolenic acid. • Feeding lipids during larval stages effectively suppresses adult seizures. • Feeding lipids rescues neurodevelopmental defects in seizure mutants. Dietary modifications often have a profound impact on the penetrance and expressivity of neurological phenotypes that are caused by genetic defects. Our previous studies in Drosophila melanogaster revealed that seizure-like phenotypes of gain-of-function voltage-gated sodium (Na v) channel mutants (paraShu , parabss1 , and paraGEFS+), as well as other seizure-prone "bang-sensitive" mutants (eas and sda), were drastically suppressed by supplementation of a standard diet with milk whey. In the current study we sought to determine which components of milk whey are responsible for the diet-dependent suppression of their hyperexcitable phenotypes. Our systematic analysis reveals that supplementing the diet with a modest amount of milk lipids (0.26% w/v) mimics the effects of milk whey. We further found that a minor milk lipid component, α-linolenic acid, contributed to the diet-dependent suppression of adult paraShu phenotypes. Given that lipid supplementation during the larval stages effectively suppressed adult paraShu phenotypes, dietary lipids likely modify neural development to compensate for the defects caused by the mutations. Consistent with this notion, lipid feeding fully rescued abnormal dendrite development of class IV sensory neurons in paraShu larvae. Overall, our findings demonstrate that milk lipids are sufficient to ameliorate hyperexcitable phenotypes in Drosophila mutants, providing a foundation for future investigation of the molecular and cellular mechanisms by which dietary lipids modify genetically induced abnormalities in neural development, physiology, and behavior. [ABSTRACT FROM AUTHOR]

The voltage‐gated sodium channel NaV1.7 is involved in various pain phenotypes and is physiologically regulated by the NaV‐β3‐subunit. Venom toxins ProTx‐II and OD1 modulate NaV1.7 channel function and may be useful as therapeutic agents and/or research tools. Here, we use patch‐clamp recordings to investigate how the β3‐subunit can influence and modulate the toxin‐mediated effects on NaV1.7 function, and we propose a putative binding mode of OD1 on NaV1.7 to rationalise its activating effects. The inhibitor ProTx‐II slowed the rate of NaV1.7 activation, whilst the activator OD1 reduced the rate of fast inactivation and accelerated recovery from inactivation. The β3‐subunit partially abrogated these effects. OD1 induced a hyperpolarising shift in the V1/2 of steady‐state activation, which was not observed in the presence of β3. Consequently, OD1‐treated NaV1.7 exhibited an enhanced window current compared with OD1‐treated NaV1.7‐β3 complex. We identify candidate OD1 residues that are likely to prevent the upward movement of the DIV S4 helix and thus impede fast inactivation. The binding sites for each of the toxins and the predicted location of the β3‐subunit on the NaV1.7 channel are distinct. Therefore, we infer that the β3‐subunit influences the interaction of toxins with NaV1.7 via indirect allosteric mechanisms. The enhanced window current shown by OD1‐treated NaV1.7 compared with OD1‐treated NaV1.7‐β3 is discussed in the context of differing cellular expressions of NaV1.7 and the β3‐subunit in dorsal root ganglion (DRG) neurons. We propose that β3, as the native binding partner for NaV1.7 in DRG neurons, should be included during screening of molecules against NaV1.7 in relevant analgesic discovery campaigns. [ABSTRACT FROM AUTHOR]

There are at least three known knockdown resistance (kdr) mutations reported globally in the human head louse Pediculus humanus capitis De Geer (Phthiraptera: Anoplura) that are associated with reduced sensitivity to pyrethroids. However, the prevalence of kdr mutation in head lice is not known in the Indian subcontinent. To identify kdr mutations in the Indian head lice population, the genomic region of the voltage‐gated sodium channel gene encompassing IIS1‐2 linker to IIS6 segments was PCR‐amplified and sequenced from P. humanus capitis samples collected from different geographic localities of India. DNA sequencing revealed the presence of four kdr mutations: M827I, T929I, L932F and L1014F. The presence of a classical kdr mutation L1014F, the most widely reported mutation across insect‐taxa associated with the kdr‐trait, is being reported for the first time in P. humanus capitis. [ABSTRACT FROM AUTHOR]

Epilepsy is a common chronic neurological disease. The International League Against Epilepsy (ILAE) defines seizures as: the transient occurrence of signs or symptoms due to abnormally excessive or synchronous neuronal activity in the brain. About 70% of patients achieve seizure⁃free with appropriate medical treatment, but nearly one⁃third of patients still do not respond to current antiepileptic drugs (AED). The alpha subunits of voltage⁃gated sodium channels (VGSC) are encoded by a highly conserved gene family, of which mutations in SCN1A, SCN2A, and SCN8A genes are important causes of central nervous system diseases. Previous studies have shown that voltage⁃gated sodium channels play an important role in the pathological process of treatment⁃resistant epilepsy (TRE). In this review, the concept, pathogenesis and drug resistance mechanism of TRE were introduced in detail, meanwhile the role and mechanisms of VGSC in TRE were reviewed. [ABSTRACT FROM AUTHOR]

Objective: Loss‐of‐function variants in SCN1A cause Dravet syndrome, the most common genetic developmental and epileptic encephalopathy (DEE). However, emerging evidence suggests separate entities of SCN1A‐related disorders due to gain‐of‐function variants. Here, we aim to refine the clinical, genetic, and functional electrophysiological features of a recurrent p.R1636Q gain‐of‐function variant, identified in four individuals at a single center. Methods: Individuals carrying the recurrent SCN1A p.R1636Q variant were identified through diagnostic testing. Whole cell voltage‐clamp electrophysiological recording in HEK‐293 T cells was performed to compare the properties of sodium channels containing wild‐type Nav1.1 or Nav1.1‐R1636Q along with both Navβ1 and Navβ2 subunits, including response to oxcarbazepine. To delineate differences from other SCN1A‐related epilepsies, we analyzed electronic medical records. Results: All four individuals had an early onset DEE characterized by focal tonic seizures and additional seizure types starting in the first few weeks of life. Electrophysiological analysis showed a mixed gain‐of‐function effect with normal current density, a leftward (hyperpolarized) shift of steady‐state inactivation, and slower inactivation kinetics leading to a prominent late sodium current. The observed functional changes closely paralleled effects of pathogenic variants in SCN3A and SCN8A at corresponding positions. Both wild type and variant exhibited sensitivity to block by oxcarbazepine, partially correcting electrophysiological abnormalities of the SCN1A p.R1636Q variant. Clinically, a single individual responded to treatment with oxcarbazepine. Across 51 individuals with SCN1A‐related epilepsies, those with the recurrent p.R1636Q variants had the earliest ages at onset. Significance: The recurrent SCN1A p.R1636Q variant causes a clinical entity with a wider clinical spectrum than previously reported, characterized by neonatal onset epilepsy and absence of prominent movement disorder. Functional consequences of this variant lead to mixed loss and gain of function that is partially corrected by oxcarbazepine. The recurrent p.R1636Q variant represents one of the most common causes of early onset SCN1A‐related epilepsies with separate treatment and prognosis implications. [ABSTRACT FROM AUTHOR]

Cycloxaprid is a novel cis-neonicotinoid, mainly acting on the nicotinic acetylcholine receptor; however, it is not clear whether cycloxaprid can act on voltage-gated ion channels. In this study, the effects of cycloxaprid on the sodium, calcium and potassium channels in central neurons acutely dissociated from Helicoverpa armigera Hübner (Lepidoptera: Noctuidae) were investigated by the whole-cell patch clamp technique. With the application of cycloxaprid, the half voltage (V0.5) of activation and inactivation of sodium channels exhibited an obvious hyperpolarizing shift around 4–16 mV and 4–14 mV, respectively. The window currents of sodium channels increased by 35.04–88.89%. The time course of recovery from inactivation was also significantly prolonged by 0.25–0.43 ms. The V0.5 of activation and inactivation of calcium channels exhibited a marked hyperpolarizing shift around 6–9 mV and 13–19 mV, respectively. The window currents of calcium channels increased by 13.82–28.97%. The time course of recovery from inactivation for calcium channels was prolonged by 0.76–16.85 ms, although not significantly. Comparatively, the peak currents and the V0.5 of activation of potassium channels showed no significant change. These results indicate that sodium and calcium channels of H. armigera are potential target sites of cycloxaprid. [ABSTRACT FROM AUTHOR]

Background: Irritable bowel syndrome (IBS) is a common functional gastrointestinal disorder, and its specific pathogenesis is still unclear. We have previously reported that TTX-resistant (TTX-R) sodium channels in colon-specific dorsal root ganglion (DRG) neurons were sensitized in a rat model of visceral hypersensitivity induced by neonatal colonic inflammation (NCI). However, the detailed molecular mechanism for activation of sodium channels remains unknown. This study was designed to examine roles for melatonin (MT) in sensitization of sodium channels in NCI rats. Methods: Colorectal distention (CRD) in adult male rats as a measure of visceral hypersensitivity. Colon-specific dorsal root ganglion (DRG) neurons were labeled with DiI and acutely dissociated for measuring excitability and sodium channel current under whole-cell patch clamp configurations. Western blot and Immunofluorescence were employed to detect changes in expression of Nav1.8 and MT2. Results: The results showed that rats exhibited visceral hypersensitivity after NCI treatment. Intrathecal application of melatonin significantly increased the threshold of CRD in NCI rats with a dose-dependent manner, but has no role in the control group. Whole-cell patch clamp recording showed that melatonin remarkably decreased the excitability and the density of TTX-R sodium channel in DRG neurons from NCI rats. The expression of MT2 receptor at the protein level was markedly lower in NCI rats. 8MP, an agonist of MT2 receptor, enhanced the distention threshold in NCI rats. Application of 8MP reversed the enhanced hypersensitivity of DRG neurons from NCI rats. 8MP also reduced TTX-R sodium current density and modulated dynamics of TTX-R sodium current activation. Conclusions: These data suggest that sensitization of sodium channels of colon DRG neurons in NCI rats is most likely mediated by MT2 receptor, thus identifying a potential target for treatment for chronic visceral pain in patients with IBS. [ABSTRACT FROM AUTHOR]

Simple Summary: Megalurothrips usitatus is the main pest of cowpea in China, mainly by feeding on plant leaves and spreading plant viruses. In this study, a new mutation putative site, I873S, was correlated with pyrethroid resistance. According to the results of the bioassay, an I873S mutation may be associated with the resistance of M. usitatus to pyrethroids. The results of this study will promote the development of research on the resistance of M. usitatus to pyrethroids and provide guidance for improving the management system of M. usitatus in the future. Pyrethroid resistance of thrips has been reported in many countries, and knockdown resistance (kdr) has been identified as a main mechanism against pyrethroids in many insects. To characterize pyrethroid resistance in Megalurothrips usitatus from the Hainan Province of China, we conducted a biological assay and sequenced the voltage-gated sodium channel gene domain II from M. usitatus field populations. It showed high resistance to the pyrethroids for 2019 and 2020, in which LC50 to lambda-cyhalothrin of M. usitatus was 1683.521 mg/L from Sanya in 2020. The LC50 value of deltamethrin was lower in Haikou than in other locations, which mean the south of Hainan has higher resistance than the north of Hainan. Two mutations of I873S and V1015M were detected in the domain II region of the sodium channel in M. usitatus; however, the mutation frequency of V1015M was only 3.33% and that of I873S was 100%. One is homozygous and the other is a heterozygous mutant type. The three thrips-sensitive strains of sodium channel 873 are highly conserved in amino acids (isoleucine), while the M. usitatus pyrethroid-resistant strains are all serine, so I873S may be related to the resistance of M. usitatus to pyrethroids. The present study will contribute to the understanding of the evolution of pyrethroids resistance and contribute to the development of resistance management of M. usitatus in Hainan. [ABSTRACT FROM AUTHOR]

Yu Shen,1 Yilei Zheng,1 Daojun Hong1,2 1Department of Neurology, The First Affiliated Hospital of Nanchang University, Nanchang, 330006, People’s Republic of China; 2Department of Medical Genetics, The First Affiliated Hospital of Nanchang University, Nanchang, 330006, People’s Republic of ChinaCorrespondence: Daojun Hong, Department of Neurology, The First Affiliated Hospital of Nanchang University, 17# Yongwaizheng St, Nanchang, 330006, People’s Republic of China, Tel/Fax +86-791-8869-2511, Email hongdaojun@hotmail.comAbstract: Over the past decades, advances in genetic sequencing have opened a new world of discovery of causative genes associated with numerous pain-related syndromes. Familial episodic pain syndromes (FEPS) are one of the distinctive syndromes characterized by early-childhood onset of severe episodic pain mainly affecting the distal extremities and tend to attenuate or diminish with age. According to the phenotypic and genetic properties, FEPS at least includes four subtypes of FEPS1, FEPS2, FEPS3, and FEPS4, which are caused by mutations in the TRPA1, SCN10A, SCN11A, and SCN9A genes, respectively. Functional studies have revealed that all missense mutations in these genes are closely associated with the gain-of-function of cation channels. Because some FEPS patients may show a relative treatability and favorable prognosis, it is worth paying attention to the diagnosis and management of FEPS as early as possible. In this review, we state the common clinical manifestations, pathogenic mechanisms, and potential therapies of the disease, and provide preliminary opinions about future research for FEPS.Keywords: familial episodic pain syndromes, voltage-gated sodium channel, transient receptor potential A1, dorsal root ganglia, nociceptive pain