Modulation Of Sodium Channels Research Articles

Importance of Zinc Homeostasis for Normal Cardiac Rhythm

<p>Current arrhythmia therapies such as ion channel blockers, catheter ablation, or implantable cardioverter defibrillators have limitations and side effects, and given the proarrhythmic risk associated with conventional, ion channel-targeted anti-arrhythmic drug therapies, a new approach to arrhythmias may be warranted. Measuring and adjusting the level of particular ions that impact heart rhythm can be a simple and low-complication strategy for preventing or treating specific arrhythmias. In addition, new medicines targeting these ions may effectively treat arrhythmias. Numerous studies have shown that intracellular and extracellular zinc concentrations impact the heart's electrical activity. Zinc has been observed to affect cardiac rhythm through a range of mechanisms. These mechanisms encompass the modulation of sodium, calcium, and potassium ion channels, as well as the influence on beta-adrenergic receptors and the enzyme adenylate cyclase. </p><p> Moreover, zinc can either counteract or induce oxidative stress, hinder calmodulin or the enzyme Ca (2+)/calmodulin-dependent protein kinase II (CaMKII), regulate cellular ATP levels, affect the processes of aging and autophagy, influence calcium ryanodine receptors, and control cellular inflammation. Additionally, zinc has been implicated in the modulation of circadian rhythm. Additionally, zinc has been implicated in the modulation of circadian rhythm. In all the above cases, the effect of zinc largely depends on the normal or increased cellular level of zinc, which shows the importance of maintaining the serum and intracellular levels of zinc within the normal range.</p>

Fibroblast growth factor homologous factors: canonical and non-canonical mechanisms of action.

Since their discovery nearly 30years ago, fibroblast growth factor homologous factors (FHFs) are now known to control the functionality of excitable tissues through a range of mechanisms. Nervous and cardiac system dysfunctions are caused by loss- or gain-of-function mutations in FHF genes. The best understood 'canonical' targets for FHF action are voltage-gated sodium channels, and recent studies have expanded the repertoire of ways that FHFs modulate sodium channel gating. Additional 'non-canonical' functions of FHFs in excitable and non-excitable cells, including cancer cells, have been reported over the past dozen years. This review summarizes and evaluates reported canonical and non-canonical FHF functions.

Sustainable Dynamic Wrinkle Efficacy: Non-Invasive Peptides as the Future of Botox Alternatives

Dynamic wrinkle reduction continues to challenge aesthetic dermatology, predominantly addressed through Botulinumtoxin (Botox) injections. Despite Botox’s robust efficacy with up to an 80% reduction in wrinkle visibility within just one week, its invasive administration and specific mechanism of soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complex inhibition prompt the exploration of safer, non-invasive alternatives. This review critically assesses recent innovations in non-invasive effects, with a focus on peptides and botanical extracts that exhibit a diverse array of mechanisms including SNARE complex inhibition, modulation of calcium and sodium channels, and interactions with acetylcholine receptors, contributing to their effectiveness in muscle relaxation on dynamic wrinkle approaches. Noteworthy peptides such as Argireline and SYN-Ake replicate the neuromodulatory effects of Botox, achieving up to a 52% reduction in wrinkles within four weeks without injections. Moreover, botanical extracts meet the rising demand for clean beauty solutions by enhancing skin elasticity and health through gentle yet potent mechanisms. However, the main concern with peptides is their low absorption rate, with only six clinical validations regarding Botox-like peptide anti-wrinkle efficacy available. These advancements not only deepen our understanding of cosmetic dermatology but also significantly influence market dynamics and consumer behavior, underscoring their pivotal role in redefining the future landscape of anti-aging effects.

Pulpitis pain relief by modulating sodium channels in trigeminal ganglia

Objectives: The pulp is the center of the tooth containing nerves and blood vessels. The condition in which the pulp becomes inflamed due to caries or periodontitis is called pulpitis. Pulpitis is a difficult-to-treat disease and causes peripheral nerve tissue changes and severe pain; however, the relationship between neuronal activity and voltage-gated sodium channel 1.7 (Nav1.7) expression in the trigeminal ganglion (TG) during pulpitis has not been well studied. In this study, we found that experimentally induced pulpitis activates Nav1.7 expression in the periphery, leading to neuronal overexpression in the TG. Thus, we sought to identify ways to regulate this process. Methods: Acute pulpitis was induced in rat maxillary molars by treating the pulp with allyl isothiocyanate (AITC). Three days later, in vivo optical imaging was used to record and compare neural activities in the TG. Western blotting was used to identify molecular changes in terms of the expression of extracellular signal-regulated kinase (ERK), c-Fos, transient receptor potential ankyrin 1 (TRPA1), and collapsin response mediator protein-2 (CRMP2) in the brain stem. Results: The results confirmed the neurological changes in the TGs of the pulpitis model, and histological and molecular biological evidence confirmed that increased Nav1.7 expression induced by pulpitis leads to pain. Furthermore, selective inhibition of Nav1.7 resulted in changes in neural activity, suggesting that pulpitis induces increased Nav1.7 expression, and that effective control of Nav1.7 could potentially reduce pain. Conclusions: The inhibition of overexpressed Nav1.7 channels may modulate nociceptive signal processing in the brain and effectively control pain associated with pulpitis.

Nanomedicine and voltage-gated sodium channel blockers in pain management: a game changer or a lost cause?

Pain, a complex and debilitating condition affecting millions globally, is a significant concern, especially in the context of post-operative recovery. This comprehensive review explores the complexity of pain and its global impact, emphasizing the modulation of voltage-gated sodium channels (VGSC or NaV channels) as a promising avenue for pain management with the aim of reducing reliance on opioids. The article delves into the role of specific NaV isoforms, particularly NaV 1.7, NaV 1.8, and NaV 1.9, in pain process and discusses the development of sodium channel blockers to target these isoforms precisely. Traditional local anesthetics and selective NaV isoform inhibitors, despite showing varying efficacy in pain management, face challenges in systemic distribution and potential side effects. The review highlights the potential of nanomedicine in improving the delivery of local anesthetics, toxins and selectiveNaV isoform inhibitors for a targeted and sustained release at the site of pain. This innovative strategy seeks to improve drug bioavailability, minimize systemic exposure, and optimize therapeutic outcomes, holding significant promise for secure pain management and enhancing the quality of life for individuals recovering from surgical procedures or suffering from chronic pain.

A binding site for phosphoinositides described by multiscale simulations explains their modulation of voltage-gated sodium channels

Voltage-gated sodium channels (Naᵥ) are membrane proteins which open to facilitate the inward flux of sodium ions into excitable cells. In response to stimuli, Naᵥ channels transition from the resting, closed state to an open, conductive state, before rapidly inactivating. Dysregulation of this functional cycle due to mutations causes diseases including epilepsy, pain conditions, and cardiac disorders, making Naᵥ channels a significant pharmacological target. Phosphoinositides are important lipid cofactors for ion channel function. The phosphoinositide PI(4,5)P2 decreases Naᵥ1.4 activity by increasing the difficulty of channel opening, accelerating fast inactivation and slowing recovery from fast inactivation. Using multiscale molecular dynamics simulations, we show that PI(4,5)P2 binds stably to inactivated Naᵥ at a conserved site within the DIV S4–S5 linker, which couples the voltage-sensing domain (VSD) to the pore. As the Naᵥ C-terminal domain is proposed to also bind here during recovery from inactivation, we hypothesize that PI(4,5)P2 prolongs inactivation by competitively binding to this site. In atomistic simulations, PI(4,5)P2 reduces the mobility of both the DIV S4–S5 linker and the DIII–IV linker, responsible for fast inactivation, slowing the conformational changes required for the channel to recover to the resting state. We further show that in a resting state Naᵥ model, phosphoinositides bind to VSD gating charges, which may anchor them and impede VSD activation. Our results provide a mechanism by which phosphoinositides alter the voltage dependence of activation and the rate of recovery from inactivation, an important step for the development of novel therapies to treat Naᵥ-related diseases.

A binding site for phosphoinositides described by multiscale simulations explains their modulation of voltage-gated sodium channels.

Voltage-gated sodium channels (Naᵥ) are membrane proteins which open to facilitate the inward flux of sodium ions into excitable cells. In response to stimuli, Naᵥ channels transition from the resting, closed state to an open, conductive state, before rapidly inactivating. Dysregulation of this functional cycle due to mutations causes diseases including epilepsy, pain conditions, and cardiac disorders, making Naᵥ channels a significant pharmacological target. Phosphoinositides are important lipid cofactors for ion channel function. The phosphoinositide PI(4,5)P2 decreases Naᵥ1.4 activity by increasing the difficulty of channel opening, accelerating fast inactivation and slowing recovery from fast inactivation. Using multiscale molecular dynamics simulations, we show that PI(4,5)P2 binds stably to inactivated Naᵥ at a conserved site within the DIV S4-S5 linker, which couples the voltage-sensing domain (VSD) to the pore. As the Naᵥ C-terminal domain is proposed to also bind here during recovery from inactivation, we hypothesize that PI(4,5)P2 prolongs inactivation by competitively binding to this site. In atomistic simulations, PI(4,5)P2 reduces the mobility of both the DIV S4-S5 linker and the DIII-IV linker, responsible for fast inactivation, slowing the conformational changes required for the channel to recover to the resting state. We further show that in a resting state Naᵥ model, phosphoinositides bind to VSD gating charges, which may anchor them and impede VSD activation. Our results provide a mechanism by which phosphoinositides alter the voltage dependence of activation and the rate of recovery from inactivation, an important step for the development of novel therapies to treat Naᵥ-related diseases.

Evolutionary origin and distribution of amino acid mutations associated with resistance to sodium channel modulators in onion thrips, Thrips tabaci

In onion thrips Thrips tabaci, reduced sensitivity of the sodium channel caused by several sodium channel mutations have been correlated with pyrethroid resistance. For this study, using mitochondrial cytochrome c oxidase subunit I gene sequences, we examined the phylogenetic relation among a total of 52 thelytokous and arrhenotokous strains with different genotypes of the sodium channel mutations. Then, we used flow cytometry to estimate their ploidy. Results showed that the strains are divisible into three groups: diploid thelytoky, triploid thelytoky, and diploid arrhenotoky. Using 23 whole genome resequencing data obtained from 20 strains out of 52, we examined their genetic relation further using principal component analysis, admixture analysis, and a fixation index. Results showed that diploid and triploid thelytokous groups are further classifiable into two based on the sodium channel mutations harbored by the respective group members (strains). The greatest genetic divergence was observed between thelytokous and arrhenotokous groups with a pair of T929I and K1774N. Nevertheless, they shared a genomic region with virtually no polymorphism around the sodium channel gene loci, suggesting a hard selective sweep. Based on these findings, we discuss the evolutionary origin and distribution of the sodium channel mutations in T. tabaci.

A binding site for phosphoinositide modulation of voltage-gated sodium channels described by multiscale simulations

A binding site for phosphoinositide modulation of voltage-gated sodium channels described by multiscale simulations

DEEPENING THEORETICAL KNOWLEDGE AND EXPLORING THE PROPERTIES OF LOCAL ANESTHETICS

Local anesthetics are indispensable agents in medical practice, offering targeted pain relief while maintaining patient consciousness. Their applications span a wide range of medical fields, including anesthesiology, surgery, and dentistry. Despite their widespread use, the complex pharmacology and potential for adverse effects necessitate a comprehensive understanding of these agents. This narrative review aims to provide an in-depth analysis of the physiology, pharmacology, and clinical applications of local anesthetics. A systematic search was conducted on PubMed, focusing on articles published in English between 2018 and 2023. Local anesthetics have evolved significantly since the first use of cocaine in the late 19th century, with newer derivatives like Lidocaine and Bupivacaine offering improved safety and efficacy. These agents are categorized into aminoesters and aminoamides based on their molecular structure, which also influences their pharmacokinetics and pharmacodynamics. The primary mechanism of action involves the modulation of voltage-gated sodium channels, although the complete mechanism remains an area of active research. Various factors, including lipid solubility, plasma pH, and pKa, influence the drug's onset, duration, and potential for toxicity. Adjuvants like adrenaline can enhance the drug's properties. Local anesthetics are a cornerstone in modern medicine, offering targeted anesthesia with a relatively favorable safety profile. Understanding their complex pharmacology is crucial for optimizing their clinical use. Future research should focus on elucidating the complete mechanisms of action and exploring the potential for new adjuvants to improve efficacy and safety.

Insights on the mechanism of flecainide in catecholaminergic polymorphic ventricular tachycardia.

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an inherited arrhythmia syndrome characterized by defective cardiac ryanodine receptor (RyR2) calcium release during times of adrenergic stimulation, resulting in bidirectional or polymorphic ventricular tachycardia. Flecainide is a class 1c anti-arrhythmic drug that has demonstrated therapeutic efficacy in treating CPVT. However, its mechanism of action remains disputed. One group proposes a direct effect of flecainide on RyR2-mediated calcium release, while another proposes an indirect effect via sodium channel blockade and modulation of intracellular calcium dynamics. In light of recent studies, this commentary aims to explore and discuss the evidence base for these potential mechanisms.

Microtubule plus-end tracking proteins: novel modulators of cardiac sodium channels and arrhythmogenesis.

The cardiac sodium channel NaV1.5 is an essential modulator of cardiac excitability, with decreased NaV1.5 levels at the plasma membrane and consequent reduction in sodium current (INa) leading to potentially lethal cardiac arrhythmias. NaV1.5 is distributed in a specific pattern at the plasma membrane of cardiomyocytes, with localization at the crests, grooves, and T-tubules of the lateral membrane and particularly high levels at the intercalated disc region. NaV1.5 forms a large macromolecular complex with and is regulated by interacting proteins, some of which are specifically localized at either the lateral membrane or intercalated disc. One of the NaV1.5 trafficking routes is via microtubules (MTs), which are regulated by MT plus-end tracking proteins (+TIPs). In our search for mechanisms involved in targeted delivery of NaV1.5, we here provide an overview of previously demonstrated interactions between NaV1.5 interacting proteins and +TIPs, which potentially (in)directly impact on NaV1.5 trafficking. Strikingly, +TIPs interact extensively with several intercalated disc- and lateral membrane-specific NaV1.5 interacting proteins. Recent work indicates that this interplay of +TIPs and NaV1.5 interacting proteins mediates the targeted delivery of NaV1.5 at specific cardiomyocyte subcellular domains, while also being potentially relevant for the trafficking of other ion channels. These observations are especially relevant for diseases associated with loss of NaV1.5 specifically at the lateral membrane (such as Duchenne muscular dystrophy), or at the intercalated disc (for example, arrhythmogenic cardiomyopathy), and open up potential avenues for development of new anti-arrhythmic therapies.

Peptide Sodium Channels Modulator Mu-Agatoxin-Aa1a Prevents Ischemia-Reperfusion Injury of Cells

Ischemia-reperfusion injury (IRI) is an irreversible functional and structural injury. Restoration of normal oxygen concentration exacerbates the emergence and development of deadly cells. One of the possible moments of reperfusion damage to cells is an increase in the intracellular concentration of sodium ions. In this article, we study the mu-agatoxin-Aa1a, a modulator of sodium channels, on the processes of IRI cells damage. The toxin was synthesized using an automatic peptide synthesizer. Hypoxia was induced by reducing the content of serum and oxygen in the CHO-K1 culture. The influence of the toxin on the level of apoptosis; intracellular concentration of sodium, calcium, and potassium ions; intracellular pH; totality of reactive oxygen species (ROS), nitric oxide (NO), and ATP; and changes in the mitochondrial potential were studied. The experiments performed show that mu-agatoxin-Aa1a effectively prevents IRI of cells. Toxin reduces the level of apoptosis and prevents a decrease in the intracellular concentration of sodium and calcium ions during IRI. Mu-agatoxin-Aa1a contributes to the maintenance of elevated intracellular pH, reduces the intracellular concentration of ROS, and prevents the decrease in intracellular NO concentration and mitochondrial potential under conditions of reoxygenation/reperfusion. An analysis of experimental data shows that the mu-agatoxin-Aa1a peptide has adaptogenic properties. In the future, this peptide can be used to prevent ischemia/reperfusion tissue damage different genesis.

The Sea Anemone Neurotoxins Modulating Sodium Channels: An Insight at Structure and Functional Activity after Four Decades of Investigation.

Many human cardiovascular and neurological disorders (such as ischemia, epileptic seizures, traumatic brain injury, neuropathic pain, etc.) are associated with the abnormal functional activity of voltage-gated sodium channels (VGSCs/NaVs). Many natural toxins, including the sea anemone toxins (called neurotoxins), are an indispensable and promising tool in pharmacological researches. They have widely been carried out over the past three decades, in particular, in establishing different NaV subtypes functional properties and a specific role in various pathologies. Therefore, a large number of publications are currently dedicated to the search and study of the structure-functional relationships of new sea anemone natural neurotoxins-potential pharmacologically active compounds that specifically interact with various subtypes of voltage gated sodium channels as drug discovery targets. This review presents and summarizes some updated data on the structure-functional relationships of known sea anemone neurotoxins belonging to four structural types. The review also emphasizes the study of type 2 neurotoxins, produced by the tropical sea anemone Heteractis crispa, five structurally homologous and one unique double-stranded peptide that, due to the absence of a functionally significant Arg14 residue, loses toxicity but retains the ability to modulate several VGSCs subtypes.

The Modulation of Ubiquinone, a Lipid Antioxidant, on Neuronal Voltage-Gated Sodium Current.

Ubiquinone, composed of a 1,4-benzoquinone and naturally produced in the body, actively participates in the mitochondrial redox reaction and functions as an endogenous lipid antioxidant, protecting against peroxidation in the pituitary-dependent hormonal system. However, the questions of if and how ubiquinone directly affects neuronal ionic currents remain largely unsettled. We investigated its effects on ionic currents in pituitary neurons (GH3 and MMQ cells) with the aid of patch-clamp technology. Ubiquinone decreased the peak amplitude of the voltage-gated Na+ current (INa) with a slowing of the inactivation rate. Neither menadione nor superoxide dismutase modified the ubiquinone-induced INa inhibition. In response to an isosceles-triangular ramp pulse, the persistent INa (INa(P)) at high- and low- threshold potentials occurred concurrently with a figure-eight hysteresis loop. With ubiquinone, the INa(P) increased with no change in the intersection voltage, and the magnitude of the voltage-dependent hysteresis of the current was enhanced. Ubiquinone was ineffective in modifying the gating of hyperpolarization-activated cation currents. In MMQ lactotrophs, ubiquinone effectively decreased the amplitude of the INa and the current inactivation rate. In sum, the effects of ubiquinone demonstrated herein occur upstream of its effects on mitochondrial redox processes, involved in its modulation of sodium channels and neuronal excitability.

Abstract P1086: Lrrc10 Is A Multifaceted Modulator Of Cardiac Calcium And Sodium Channels

L-type calcium channels (LTCC) are vital for heart physiology as they allow entry of calcium to the cardiomyocyte, ultimately leading to contraction. These channels are exquisitely modulated by auxiliary subunits and a vast array of regulatory proteins. Heart-specific leucine-rich repeat-containing protein 10 (Lrrc10) plays a key role as a regulator of LTCC. Previous work has shown that Lrrc10 knockdown in zebrafish disrupts development of the cardiac tube, while ablation of Lrrc10 in mice results in heart dysfunction and maladaptation to increased cardiac afterload. Moreover, human mutations in Lrrc10 gene have been linked to dilated cardiomyopathy, and sudden unexplained nocturnal death syndrome (SUNDS). Still, the molecular mechanisms underlying Lrrc10 regulation of LTCC is not fully established. Beyond this, it is unknown whether Lrrc10 modulates other cardiac ion channels. Here, we hypothesized that Lrrc10 serves as a versatile regulator of four-domain voltage-gated ion channels, while mutations in Lrrc10 differentially disrupt channel regulation. Using whole-cell and single-channel electrophysiology, we found that Lrrc10: 1) upregulates LTCC currents by increasing peak open probability; 2) accelerates calcium-dependent inactivation; and 3) evokes a hyperpolarizing-shift in voltage-dependence of activation. Flow cytometric FRET 2-hybrid assay showed that Lrrc10 interacts with LTCC cytoplasmic subunits, specifically the N- and C-termini. We further used FRET 2-hybrid analysis to evaluate the interaction of Lrrc10 with related cardiac ion channels. We observed robust Lrrc10 interaction with Na V 1.5 channels. Multi-channel electrophysiology recordings revealed increased late sodium currents, suggesting that Lrrc10 also modulates Na V 1.5 activity. Additionally, electrophysiological studies showed that Lrrc10 variants linked to dilated cardiomyopathy and SUNDS disparately alter modulation of calcium and sodium channels. In conclusion, Lrrc10 is a multifaceted regulator of four-domain, voltage-gated cardiac ion channels, a finding that will lend critical insights into heart function and disease.

Neurotoxic and cytotoxic peptides underlie the painful stings of the tree nettle Urtica ferox

The stinging hairs of plants from the family Urticaceae inject compounds that inflict pain to deter herbivores. The sting of the New Zealand tree nettle (Urtica ferox) is among the most painful of these and can cause systemic symptoms that can even be life-threatening; however, the molecular species effecting this response have not been elucidated. Here we reveal that two classes of peptide toxin are responsible for the symptoms of U. ferox stings: Δ-Uf1a is a cytotoxic thionin that causes pain via disruption of cell membranes, while β/δ-Uf2a defines a new class of neurotoxin that causes pain and systemic symptoms via modulation of voltage-gated sodium (NaV) channels. We demonstrate using whole-cell patch-clamp electrophysiology experiments that β/δ-Uf2a is a potent modulator of human NaV1.5 (EC50: 55 nM), NaV1.6 (EC50: 0.86 nM), and NaV1.7 (EC50: 208 nM), where it shifts the activation threshold to more negative potentials and slows fast inactivation. We further found that both toxin classes are widespread among members of the Urticeae tribe within Urticaceae, suggesting that they are likely to be pain-causing agents underlying the stings of other Urtica species. Comparative analysis of nettles of Urtica, and the recently described pain-causing peptides from nettles of another genus, Dendrocnide, indicates that members of tribe Urticeae have developed a diverse arsenal of pain-causing peptides.

Medicinal Plants Used to Treat Epilepsy

Epilepsy is a neuropsychological disorder, in which occurs due to over release of neurotransmitter substance. Epilepsy is different from the seizures, a seizure occurs due to abnormal and excessive hyper synchronous release from an aggregate CNS. There are lot of drugs available in market to treat epilepsy. But the major problem behind these drugs is patient faces chronic side effects. There are number of patients who faces resistant to antiepileptic drugs. Since from the ancient time, plants are used by the people to treat epileptic seizures. Different herbs plays vital role in prevention and treatment of convulsions. Convulsion is the second most common neurological disorder which is present among the world’s population. Approx. 1% of the world’s population suffers from this neurological disorder. Most of the patient requires polytherapy to cure from convulsions with minimum resistant and disadvantages, but somehow still this therapy does not show 100% cured effect. Hence, this review represents some of the herbal plants which can cure this condition and motivates researchers and patients to turn towards herbal remedies. Herbal drugs shows same action on their target side as that of synthetic drugs. Plants with certain active constituents shows pharmacological action on various organs in human body. Various herbal drugs can combined together to show antiepileptic effect through various mechanisms such as ant oxidation, anti-inflammation, modulation of NMDA channels and sodium channel, GABAergic effect enhancement and neuroprotection.

A Two-Sequence, Four-Period, Crossover, Full-Replicate Study to Demonstrate Bioequivalence of Carbamazepine Extended-Release Tablets in Healthy Subjects under Fasting and Fed Conditions

Carbamazepine is a first-line antiepileptic drug (AED) used for the treatment of partial and tonic-clonic seizures. We conducted an open label, balanced, randomized, two-treatment, two-sequence, four-period, single oral dose, full-replicate crossover study to assess and compare the bioequivalence of test product Carbamazepine extended release tablets USP 400 mg with reference product Tegretol®-XR 400 mg (Carbamazepine extended release tablets), respectively in healthy subjects under fasting and fed conditions. Blood samples were collected pre-dose and at regular intervals post-dose up to 240.00 hours. The plasma concentration was analyzed by a validated LC-MS/MS method and the reference-scaled and the unscaled procedure was used to determine bioequivalence for the pharmacokinetics parameters, Cmax, AUC0–t, AUC0-inf, Tmax, T½, Kel and AUC extrapolated was calculated. The results showed that the geometric mean ratios of Cmax, AUC0–t and AUC0-inf were 113.04%, 108.33% and 108.15% respectively, in the fasting conditions and 113.99%, 110.13% and 111.41%, respectively, in the fed conditions and the 90% confidence intervals were all within the range of 80.00% to 125.00%. It can be concluded from the result that the test product Carbamazepine extended release tablets based on osmotic release system (OROS) are bioequivalent to the reference product Tegretol®-XR tablets.
 Keywords: Bioequivalence, Carbamazepine, Sodium Channel Modulators and Epilepsy

Generation of Human Nociceptor-Enriched Sensory Neurons for the Study of Pain-Related Dysfunctions.

In vitro models of the peripheral nervous system would benefit from further refinements to better support studies on neuropathies. In particular, the assessment of pain-related signals is still difficult in human cell cultures. Here, we harnessed induced pluripotent stem cells (iPSCs) to generate peripheral sensory neurons enriched in nociceptors. The objective was to generate a culture system with signaling endpoints suitable for pharmacological and toxicological studies. Neurons generated by conventional differentiation protocols expressed moderate levels of P2X3 purinergic receptors and only low levels of TRPV1 capsaicin receptors, when maturation time was kept to the upper practically useful limit of 6 weeks. As alternative approach, we generated cells with an inducible NGN1 transgene. Ectopic expression of this transcription factor during a defined time window of differentiation resulted in highly enriched nociceptor cultures, as determined by functional (P2X3 and TRPV1 receptors) and immunocytochemical phenotyping, complemented by extensive transcriptome profiling. Single cell recordings of Ca2+-indicator fluorescence from >9000 cells were used to establish the “fraction of reactive cells” in a stimulated population as experimental endpoint, that appeared robust, transparent and quantifiable. To provide an example of application to biomedical studies, functional consequences of prolonged exposure to the chemotherapeutic drug oxaliplatin were examined at non-cytotoxic concentrations. We found (i) neuronal (allodynia-like) hypersensitivity to otherwise non-activating mechanical stimulation that could be blocked by modulators of voltage-gated sodium channels; (ii) hyper-responsiveness to TRPV1 receptor stimulation. These findings and several other measured functional alterations indicate that the model is suitable for pharmacological and toxicological studies related to peripheral neuropathies.