Subunit Of Voltage-gated Calcium Channels Research Articles

Ca2+ channel and active zone protein abundance intersects with input-specific synapse organization to shape functional synaptic diversity.

Synaptic heterogeneity is a hallmark of nervous systems that enables complex and adaptable communication in neural circuits. To understand circuit function, it is thus critical to determine the factors that contribute to the functional diversity of synapses. We investigated the contributions of voltage-gated calcium channel (VGCC) abundance, spatial organization, and subunit composition to synapse diversity among and between synapses formed by two closely related Drosophila glutamatergic motor neurons with distinct neurotransmitter release probabilities (Pr). Surprisingly, VGCC levels are highly predictive of heterogeneous Pr among individual synapses of either low- or high-Pr inputs, but not between inputs. We find that the same number of VGCCs are more densely organized at high-Pr synapses, consistent with tighter VGCC-synaptic vesicle coupling. We generated endogenously tagged lines to investigate VGCC subunits in vivo and found that the α2δ-3 subunit Straightjacket along with the CAST/ELKS active zone (AZ) protein Bruchpilot, both key regulators of VGCCs, are less abundant at high-Pr inputs, yet positively correlate with Pr among synapses formed by either input. Consistently, both Straightjacket and Bruchpilot levels are dynamically increased across AZs of both inputs when neurotransmitter release is potentiated to maintain stable communication following glutamate receptor inhibition. Together, these findings suggest a model in which VGCC and AZ protein abundance intersects with input-specific spatial and molecular organization to shape the functional diversity of synapses.

HYPERTROPHIC CARDIOMYOPATHY AND MYBPC3 VARIANT - A CLINICAL CASE

Abstract Introduction Hypertrophic cardiomyopathy is a primary pathology of the cardiac muscle. Sarcomeric forms of hypertrophic cardiomyopathy (HCM) often have autosomal dominant transmission. A pathogenetic or likely pathogenetic mutation affecting genes encoding sarcomeric proteins is present in 30-60% of cases. In this study, we present a case of a family affected by hypertrophic cardiomyopathy with a mutation classified as of uncertain significance in the MYBPC3 gene. Clinical Case Mr. AA, 74 years old, attended the cardiomyopathy outpatient clinic of our hospital in June 2021 due to worsening heart failure with an hypertrophic phenotype. His medical history reported an increase in the thickness of the interventricular septum (IVS) since 1985. In 2015, the patient underwent pacemaker implantation for symptomatic 2:1 atrioventricular block associated with syncope and complete left bundle branch block. Since 2016, he had paroxysmal atrial fibrillation complicated by an ischemic stroke in 2019 with subtherapeutic INR. Cardiac magnetic resonance imaging (MRI) or genetic evaluation had never been performed. During the visit, the patient reported that his sister (AG, 73 years old) had undergone tests due to diffuse negative T waves findings in a previous ECG, revealing the presence of a long myocardial bridge of the left anterior descending artery (LAD). No family history of sudden cardiac death was reported. The echocardiogram of AA showed LV hypertrophy (septal wall thickness/posterior wall thickness 18/15 mm, respectively) with an ejection fraction of 36%. Suspecting sarcomeric HCM, a genetic test (TruSight One Expanded Illumina) was performed, revealing two variants of uncertain significance in heterozygosity in the CACNA1C - Calcium Voltage-Gated Channel Subunit Alpha1 C gene (c.2460G>C p.(Lys820Asn)) and MYBPC3 gene (c.2030C>T p.(Pro677Leu)). After a few months, AG presented MRI results suggestive of HCM apical variant (Figure 1). The genetic consultant recommended family screening, and the pedigree is shown in Figure 2. All carriers of the CACNA1C mutation had a negative phenotype. AG's son, IF, 56 years old, carriers of MYBPC3 mutation, presented an MRI compatible with early-stage HCM (Figure 3). His son, carriers of MYBPC3 mutation as well, is now awaiting a cardiac MRI. Conclusions In the family presented here, the MYBPC3 variant (c.2030C>T p.(Pro677Leu)) appears to be correlated with the development of sarcomeric hypertrophic cardiomyopathy. Registry studies with a large sample size are desirable to accurately classify variants of uncertain significance, which are becoming more common due to the widespread use of genetic tests.

Molecular Mechanisms and Therapeutic Potential of Gabapentin with a Focus on Topical Formulations to Treat Ocular Surface Diseases.

Gabapentin (GBP) was originally developed as a potential agonist for Gamma-Amino-Butyric-Acid (GABA) receptors, aiming to inhibit the activation of pain-signaling neurons. Contrary to initial expectations, it does not bind to GABA receptors. Instead, it exhibits several distinct pharmacological activities, including: (1) binding to the alpha-2-delta protein subunit of voltage-gated calcium channels in the central nervous system, thereby blocking the excitatory influx of calcium; (2) reducing the expression and phosphorylation of CaMKII via modulation of ERK1/2 phosphorylation; (3) inhibiting glutamate release and interfering with the activation of NMDA receptors; (4) enhancing GABA synthesis; (5) increasing cell-surface expression of δGABA_A receptors, contributing to its antinociceptive, anticonvulsant, and anxiolytic-like effects. Additionally, GBP displays (6) inhibition of NF-kB activation and subsequent production of inflammatory cytokines, and (7) stimulation of the purinergic adenosine A1 receptor, which supports its anti-inflammatory and wound-healing properties. Initially approved for treating seizures and postherpetic neuralgia, GBP is now broadly used for various conditions, including psychiatric disorders, acute and chronic neuropathic pain, and sleep disturbances. Recently, as an eye drop formulation, it has also been explored as a therapeutic option for ocular surface discomfort in conditions such as dry eye, neurotrophic keratitis, corneal ulcers, and neuropathic ocular pain. This review aims to summarize the evidence supporting the molecular effects of GBP, with a special emphasis on its applications in ocular surface diseases.

NRN1 epistasis with BDNF and CACNA1C: mediation effects on symptom severity through neuroanatomical changes in schizophrenia

The expression of Neuritin-1 (NRN1), a neurotrophic factor crucial for neurodevelopment and synaptic plasticity, is enhanced by the Brain Derived Neurotrophic Factor (BDNF). Although the receptor of NRN1 remains unclear, it is suggested that NRN1’s activation of the insulin receptor (IR) pathway promotes the transcription of the calcium voltage-gated channel subunit alpha1 C (CACNA1C). These three genes have been independently associated with schizophrenia (SZ) risk, symptomatology, and brain differences. However, research on how they synergistically modulate these phenotypes is scarce. We aimed to study whether the genetic epistasis between these genes affects the risk and clinical presentation of the disorder via its effect on brain structure. First, we tested the epistatic effect of NRN1 and BDNF or CACNA1C on (i) the risk for SZ, (ii) clinical symptoms severity and functionality (onset, PANSS, CGI and GAF), and (iii) brain cortical structure (thickness, surface area and volume measures estimated using FreeSurfer) in a sample of 86 SZ patients and 89 healthy subjects. Second, we explored whether those brain clusters influenced by epistatic effects mediate the clinical profiles. Although we did not find a direct epistatic impact on the risk, our data unveiled significant effects on the disorder’s clinical presentation. Specifically, the NRN1-rs10484320 x BDNF-rs6265 interplay influenced PANSS general psychopathology, and the NRN1-rs4960155 x CACNA1C-rs1006737 interaction affected GAF scores. Moreover, several interactions between NRN1 SNPs and BDNF-rs6265 significantly influenced the surface area and cortical volume of the frontal, parietal, and temporal brain regions within patients. The NRN1-rs10484320 x BDNF-rs6265 epistasis in the left lateral orbitofrontal cortex fully mediated the effect on PANSS general psychopathology. Our study not only adds clinical significance to the well-described molecular relationship between NRN1 and BDNF but also underscores the utility of deconstructing SZ into biologically validated brain-imaging markers to explore their mediation role in the path from genetics to complex clinical manifestation.

Altered Hippocampal Activation in Seizure-Prone CACNA2D2 Knock-out Mice.

The voltage-gated calcium channel subunit α2δ-2 controls calcium-dependent signaling in neurons, and loss of this subunit causes epilepsy in both mice and humans. To determine whether mice without α2δ-2 demonstrate hippocampal activation or histopathological changes associated with seizure activity, we measured expression of the activity-dependent gene c-fos and various histopathological correlates of temporal lobe epilepsy (TLE) in hippocampal tissue from wild-type (WT) and α2δ-2 knock-out (CACNA2D2 KO) mice using immunohistochemical staining and confocal microscopy. Both genotypes demonstrated similarly sparse c-fos and ΔFosB expressions within the hippocampal dentate granule cell layer (GCL) at baseline, consistent with no difference in basal activity of granule cells between genotypes. Surprisingly, when mice were assayed 1 h after handling-associated convulsions, KO mice had fewer c-fos-positive cells but dramatically increased ΔFosB expression in the dentate gyrus compared with WT mice. After administration of a subthreshold pentylenetetrazol dose, however, KO mice dentate had significantly more c-fos expression compared with WT mice. Other histopathological markers of TLE in these mice, including markers of neurogenesis, glial activation, and mossy fiber sprouting, were similar between WT and KO mice, apart from a small but statistically significant increase in hilar mossy cell density, opposite to what is typically found in mice with TLE. This suggests that the differences in seizure-associated dentate gyrus function in the absence of α2δ-2 protein are likely due to altered functional properties of the network without associated structural changes in the hippocampus at the typical age of seizure onset.

α2δ1-mediated maladaptive sensory plasticity disrupts adipose tissue homeostasis following spinal cord injury

Spinal cord injury (SCI) increases the risk of cardiometabolic disorders, including hypertension, dyslipidemia, and insulin resistance. Not only does SCI lead to pathological expansion of adipose tissue, but it also leads to ectopic lipid accumulation in organs integral to glucose and insulin metabolism. The pathophysiological changes that underlie adipose tissue dysfunction after SCI are unknown. Here, we find that SCI exacerbates lipolysis in epididymal white adipose tissue (eWAT). Whereas expression of the α2δ1 subunit of voltage-gated calcium channels increases in calcitonin gene-related peptide-positive dorsal root ganglia neurons that project to eWAT, conditional deletion of the gene encoding α2δ1 in these neurons normalizes eWAT lipolysis after SCI. Furthermore, α2δ1 pharmacological blockade through systemic administration of gabapentin also normalizes eWAT lipolysis after SCI, preventing ectopic lipid accumulation in the liver. Thus, our study provides insight into molecular causes of maladaptive sensory processing in eWAT, facilitating the development of strategies to reduce metabolic and cardiovascular complications after SCI.

Quercetin alleviates chronic unpredictable mild stress-induced depression-like behavior by inhibiting NMDAR1 with α2δ-1 in rats.

Depression is a serious mental disorder and the most prevalent cause of disability and suicide worldwide. Chronic unpredictable mild stress (CUMS) can lead to a significant acceleration of depression development. Quercetin (Que) is a flavonoid compound with a wide range of pharmacological effects. Recent studies have shown that quercetin can improve CUMS-induced depression-like behavior, but the mechanism of its improvement is still unclear. α2δ-1 is a regulatory subunit of voltage-gated calcium channel, which can interact with N-methyl-D-aspartate receptor (NMDAR) to form a complex. In this study, we found that Que could inhibit the increase of α2δ-1 and NMDAR expression in rat hypothalamus induced by CUMS. In pain, chronic hypertension and other studies have shown that α2δ-1 interacts with the NMDAR to form a complex, which subsequently affects the expression level of NMDAR. Consequently, the present study aimed to investigate the antidepressant effect of Que invivo and invitro and to explore its mechanism of action in terms of the interaction between α2δ-1 and NMDAR. Rats were randomly exposed to two stressors every day for 4 weeks to establish a CUMS rat model, then sucrose preference test (SPT), forced swimming test (FST), tail suspension test (TST), and open field test (OFT) were performed to detect the behavior of CUMS rats, so as to evaluate whether the CUMS rat model was successfully established and the improvement effect of Que on CUMS-induced depression-like behavior in rats. Experimental techniques such as serum enzyme-linked immunosorbent assay (ELISA), immunofluorescence, Western blot, and co-immunoprecipitation, as well as invitro experiments, were used to investigate the mechanisms by which Que exerts its antidepressant effects. Behavioral and ELISA test results showed that Que could produce a reduction in the excitability of the hypothalamic-pituitary-adrenal (HPA) axis in CUMS rats and lead to significant improvements in their depressive behavior. Western blot, immunofluorescence, and co-immunoprecipitation experiments showed that Que produced a decrease in NMDAR1 and α2δ-1 expression levels and interfered with α2δ-1 and NMDAR1 binding. In addition, the neural regulation mechanism of Que on antidepressant effect in PC12 cells knocked out α2δ-1 gene was further verified. Cellular experiments demonstrated that Que led to a reversal of up-regulation of NMDAR1 and α2δ-1 expression levels in corticosterone-injured PC12 cells, while Que had no effects on NMDAR1 expression in PC12 cells with the α2δ-1 gene knockout. Que has a good antidepressant effect and can significantly improve the depression-like behavior caused by CUMS. It exerts antidepressant effects by inhibiting the expression level of α2δ-1, interfering with the interaction between α2δ-1 and NMDAR, and then reducing the excitability of the HPA axis.

Molecular docking analysis of marine compounds with voltage gated calcium channel for potential anti-epileptic molecules.

Epileptic seizures are directly linked with an anomalous influx of extracellular calcium or sodium anions through voltage-gated channels disturb the chemical and electrical gradients, resulting in seizures or jerking moments. Voltage-gated calcium channel (VGCC) subunit α2δ-1 is the binding site for gabapentinoids used to treat epilepsy and neuropathic pain. However, this class of drugs showed severe side effects associated with CNS and respiratory depression. Hence, we screened a total of 2583 phytochemicals from the Comprehensive Marine Natural Products Database for their drug likeliness and pharmacokinetics (ADME/T) properties. The selected phytochemicals were docked with the VGCC α2δ-1 protein target and the marketed AED Pregabalin is used as standard. The docking results helped to select 45 docked compounds with better binding affinity, among which Acanthiline A showed the maximum binding affinity with the binding energy of -11.9 kcal/mol, thus reflecting its potential anti-epileptic activity.

Towards Multitargeted Ligands as Pain Therapeutics: Dual Ligands of the Cavα2δ-1 Subunit of Voltage-Gated Calcium Channel and the μ-Opioid Receptor.

The synthesis and pharmacological activity of a new series of dual ligands combining activities towards the α2δ-1 subunit of voltage-gated calcium channels (Cavα2δ-1) and the μ-opioid receptor (MOR) as novel pain therapeutics are reported. A careful exploration of the pharmacophores related to both targets, which in principle had few common characteristics, led to the design of novel compounds exhibiting both activities. The construction of the dual ligands started from published Cavα2δ-1 ligands, onto which MOR ligand pharmacophoric elements were added. This exercise led to new amino-acidic substances with good affinities on both targets as well as good metabolic and physicochemical profiles and low potential for drug-drug interactions. A representative compound, (2S,4S)-4-(4-chloro-3-(((cis)-4-(dimethylamino)-4-phenylcyclohexyl)methyl)-5-fluorophenoxy)pyrrolidine-2-carboxylic acid, displayed promising analgesic activities in several in vivo pain models as well as a reduced side-effect profile in relation to morphine.

The PTB and PRR domains of numb regulate neurite outgrowth by influencing voltage-gated calcium channel expression and kinetics

Numb is an evolutionarily conserved protein that regulates the differentiation of neuronal progenitor cells through unknown mechanisms. Numb has four alternative splice variants with different lengths of phosphotyrosine-binding (PTB) and proline-rich regions (PRR) domains. In this study, we demonstrated that Numb expression was increased in the primary cultures of rat cortical and hippocampal neurons over time in vitro, and Numb antisense inhibited neurite outgrowth. We verified that cells overexpressing short PTB (SPTB) or long PTB (LPTB) domains exhibited differentiation or proliferation, respectively. SPTB-mediated differentiation was related to the PRR domains, as cells expressing SPTB/LPRR had longer dendrites and more branched dendrites than cells expressing SPTB/SPRR. The differentiation of both cell types was completely blocked by the Ca2+ chelator. Western blot analysis revealed the increased total protein expression of voltage-gated calcium channel (VGCC) subunit α1C and α1D in cells expressing SPTB and LPTB Numb. The increased expression of the VGCC β3 subunit was only observed in cells expressing SPTB Numb. Immunocytochemistry further showed that SPTB-mediated cell differentiation was associated with increased membrane expression of VGCC subunits α1C, α1D and β3, which corresponded to the higher Ca2+ current (ICa) densities. Furthermore, we found that VGCC of cells transfected with SPTB/SPRR or SPTB/LPRR Numb isoforms exhibit steady-state inactivation (SSI) in both differentiated and undifferentiated phenotypes. A similar SSI of VGCC was observed in the differentiated cells transfected with SPTB/SPRR or SPTB/LPRR Numb isoforms, whereas a left shift SSI of VGCC in cells expressing SPTB/LPRR was detected in the undifferentiated cells. Collectively, these data indicate that SPTB domain is essential for neurite outgrowth involving in membrane expression of VGCC subunits, and LPRR plays a role in neuronal branching and the regulation of VGCC inactivation kinetics.

Association Study of CACNA1E Gene Polymorphisms and Sudden Sensorineural Hearing Loss

Background and Objectives The present study aimed to investigate whether single nucleotide polymorphisms (SNPs) in calcium voltage-gated channel subunit alpha1E (CACNA1E) are associated with sudden sensorineural hearing loss (SSNHL).Subjects and Method Eighty-one Korean SSNHL patients and 455 healthy subjects were selected from a single tertiary hospital. Human genomic DNA extracted from the peripheral blood samples and five exon regions of SNPs in CACNA1E were genotyped by direct sequencing.Results In rs357737760, the A/T genotype was present with significantly higher frequency among the SSNHL patients than the T/T (<i>p</i>=0.0003) genotype. In rs34488539, the C/T genotype was present with significantly higher frequency among SSNHL patients than the C/C genotype (<i>p</i>=0.0003). In rs4652678, the C/T genotype was present with significantly higher frequency among the SSNHL patients than the T/T genotype (codominant model, <i>p</i>=0.0079) (dominant model, <i>p</i>=0.0027) (overdominant model, <i>p</i>=0.0021). In rs199930, the C/T genotype was present with significantly higher frequency among the SSNHL patients than the C/C genotype (codominant model, <i>p</i>=0.0081) (dominant model, <i>p</i>=0.0028) (overdominant model, <i>p</i>=0.0022). In rs704326, the A/A genotype was present with significantly lower frequency among the SSNHL patients than the G/G genotype (codominant model, <i>p</i>=0.0003) (recessive model, <i>p</i>=0.0001).Conclusion We found rs35737760, rs344488539, rs4652678 and rs199930 SNPs of CACNA1E to be highly associated with SSNHL. Only rs704326 SNP of CACNA1E is found with low association with SSNHL.

Mild Intermittent Cold Stimulation Affects Cardiac Substance Metabolism via the Neuroendocrine Pathway in Broilers.

This study aimed to investigate the impact of cold adaptation on the neuroendocrine and cardiac substance metabolism pathways in broilers. The broilers were divided into the control group (CC), cold adaptation group (C3), and cold-stressed group (C9), and experimental period was divided into the training period (d 1-35), recovery period (d 36-43), and cold stress period (d 43-44). During the training period, the CC group was reared at ambient temperature, while C3 and C9 groups were reared at 3 °C and 9 °C lower than the ambient temperature, respectively, for 5 h/d at 1 d intervals. During the recovery period, all the groups were maintained at 20 °C. Lastly, during the cold stress period, the groups were divided into two sub-groups, and each sub-group was placed at 10 °C for 12 h (Y12) or 24 h (Y24) for acute cold stimulation. The blood, hypothalamic, and cardiac tissues samples were obtained from all the groups during the training, recovery, and acute stress periods. The results revealed that the transcription of calcium voltage-gated channel subunit alpha 1 C (CACNAIC) was increased in the hypothalamic tissues of the C3 group (p < 0.05). Moreover, compared to the CC group, the serum norepinephrine (NE) was increased in the C9 group (p < 0.05), but insulin (INS) was decreased in the C9 group (p < 0.05). In addition, the transcription of the phosphoinositide-3 kinase (PI3K), protein kinase B (Akt), mammalian target of rapamycin (mTOR), SREBP1c, FASN, ACC1, and SCD genes was down-regulated in the C3 and C9 groups (p < 0.05); however, their expression increased in the C3 and C9 groups after acute cold stimulation (p < 0.05). Compared to the CC group, the transcription of forkhead box O1 (FoxO1), PEPCK, G6Pase, GLUT1, HK1, PFK, and LDHB genes was up-regulated in the C3 and C9 groups (p < 0.05. Furthermore, compared to the CC and C9 groups, the protein and mRNA expressions of heat shock protein (HSP) 70 and HSP90 were significantly increased in the C3 group (p < 0.05). These results indicate that intermittent cold training can enhance cold stress tolerance in broilers by regulating their neuroendocrine and cardiac substance metabolism pathways.

Role of α2δ-3 in regulating calcium channel localization at presynaptic active zones during homeostatic plasticity.

The homeostatic modulation of synaptic transmission is an evolutionarily conserved mechanism that is critical for stabilizing the nervous system. At the Drosophila neuromuscular junction (NMJ), presynaptic homeostatic potentiation (PHP) compensates for impairments in postsynaptic glutamate receptors due to pharmacological blockade or genetic deletion. During PHP, there is an increase in presynaptic neurotransmitter release, counteracting postsynaptic changes and restoring excitation to baseline levels. Previous studies have shown that α2δ-3, an auxiliary subunit of voltage-gated calcium channels (VGCCs), is essential for both the rapid induction and sustained expression of PHP at the Drosophila NMJ. However, the molecular mechanisms by which α2δ-3 regulates neurotransmitter release during PHP remain to be elucidated. In this study, we utilized electrophysiological, confocal imaging, and super-resolution imaging approaches to explore how α2δ-3 regulates synaptic transmission during PHP. Our findings suggest that α2δ-3 governs PHP by controlling the localization of the calcium channel pore-forming α1 subunit at presynaptic release sites, or active zones. Moreover, we examined the role of two structural domains within α2δ-3 in regulating neurotransmitter release and calcium channel localization. Our results highlight that these domains in α2δ-3 serve distinct functions in controlling synaptic transmission and presynaptic calcium channel abundance, at baseline in the absence of perturbations and during PHP. In summary, our research offers compelling evidence that α2δ-3 is an indispensable signaling component for controlling calcium channel trafficking and stabilization in homeostatic plasticity.

Drug clustering to anticipate new aspects of drug safety profile: Application to gabapentinoids and other voltage-gated calcium channel ligand drugs.

Gabapentin and pregabalin bind to α2-δ subunit of voltage-gated calcium channels (Cav ). Other drugs targeting Cav include cardiovascular calcium channel blockers (CCBs) and anticonvulsants (levetiracetam, ethosuximide and zonisamide). In addition to pharmacodynamics, the safety profile of gabapentinoids seems to overlap with the one of cardiovascular CCBs (oedema) and Cav -blocking anticonvulsants (suicide and ataxia). The objective of this study was to cluster the safety profile of different Cav -ligand drugs by focusing on whether gabapentinoids present a distinct adverse drug reaction (ADR) signature from cardiovascular CCBs and anticonvulsants. We extracted all ADRs with at least one significant disproportionate reporting (reporting odds ratio) related to gabapentinoids, CCBs or anticonvulsants in VigiBase. After principal component analysis preprocessing, a hierarchical ascendent classification was performed to cluster gabapentinoids and other Cav -ligand drugs that share a similar ADR signature. The robustness of the results was determined through four sensitivity analyses, varying on the dataset or the clustering method. A total of 16 drugs and 65 ADRs were included. Gabapentinoids were in Cluster #1, which included eight other drugs (isradipine, nicardipine, lacidipine, lercanidipine, ethosuximide, levetiracetam, zonisamide and nimodipine). Cluster #2 contained two drugs (diltiazem and verapamil) and Cluster #3 contained four drugs (amlodipine, felodipine, nifedipine and nitrendipine). The clustering results were consistent in all sensitivity analyses. The safety profile of gabapentinoids overlaps with those of some dihydropyridine CCBs and Cav -blocking anticonvulsants. These results could be used to anticipate some unidentified ADRs of gabapentinoids from information accumulated with older drugs and sharing a common molecular target and ADR signature.

Mechanism of Analgesia by Gabapentinoid Drugs: Involvement of Modulation of Synaptogenesis and Trafficking of Glutamate-Gated Ion Channels.

Gabapentinoids have clinically been used for treating epilepsy, neuropathic pain, and several other neurologic disorders for >30 years; however, the definitive molecular mechanism responsible for their therapeutic actions remained uncertain. The conventional pharmacological observation regarding their efficacy in chronic pain modulation is the weakening of glutamate release at presynaptic terminals in the spinal cord. While the α2/δ-1 subunit of voltage-gated calcium channels (VGCCs) has been identified as the primary drug receptor for gabapentinoids, the lack of consistent effect of this drug class on VGCC function is indicative of a minor role in regulating this ion channel's activity. The current review targets the efficacy and mechanism of gabapentinoids in treating chronic pain. The discovery of interaction of α2/δ-1 with thrombospondins established this protein as a major synaptogenic neuronal receptor for thrombospondins. Other findings identified α2/δ-1 as a powerful regulator of N-methyl-D-aspartate receptor (NMDA) and alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor (AMPAR) by potentiating the synaptic expression, a putative pathophysiological mechanism of neuropathic pain. Further, the interdependent interactions between thrombospondin and α2/δ-1 contribute to chronic pain states, while gabapentinoid ligands efficaciously reverse such pain conditions. Gabapentin normalizes and even blocks NMDAR and AMPAR synaptic targeting and activity elicited by nerve injury. SIGNIFICANCE STATEMENT: Gabapentinoid drugs are used to treat various neurological conditions including chronic pain. In chronic pain states, gene expression of cacnα2/δ-1 and thrombospondins are upregulated and promote aberrant excitatory synaptogenesis. The complex trait of protein associations that involve interdependent interactions between α2/δ-1 and thrombospondins, further, association of N-methyl-D-aspartate receptor and alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor with the C-tail of α2/δ-1, constitutes a macromolecular signaling complex that forms the crucial elements for the pharmacological mode of action of gabapentinoids.

Effects of Remimazolam on Intracellular Calcium Dynamics in Myotubes Derived from Patients with Malignant Hyperthermia and Functional Analysis of Type 1 Ryanodine Receptor Gene Variants.

Remimazolam is a novel general anesthetic and its safety in patients with malignant hyperthermia (MH) is unknown. We used myotubes derived from the skeletal muscle of patients with MH to examine the response to ryanodine receptor 1 (RYR1) agonist and remimazolam in MH-susceptible patients. Patients underwent muscle biopsy for the Ca2+-induced Ca2+ release (CICR) rate test, a diagnostic tool for MH in Japan. Ten patients had myotubes obtained from skeletal muscle cultures, and the genes associated with malignant hyperthermia in these patients were analyzed. The EC50 of caffeine, cresol, and remimazolam to induce intracellular calcium concentration change were compared between myotubes from CICR-negative genetic test patients and myotubes from other patients. Eight of the ten were CICR-positive, five of whom had RYR1 causative gene mutations or variants. Two patients had CICR-negative genetic tests, and as expected had the highest EC50 (the concentration of a drug that gives a half-maximal response) in response to caffeine, 4CmC and remimazolam. Three patients had a positive CICR but no known variants in RYR1 or CACNA1S (voltage-gated calcium channel subunit alpha1S). Myotubes in these patients had significantly lower EC50s for all agents than myotubes in CICR-negative patients. When myotubes from a patient who was CICR-negative and had no gene variant were used as a control, myotubes from CICR-positive patients were more hyper-responsive than controls to all stimulants used. The EC50 for remimazolam was lowest for myotubes from CICR-positive, RYR1-mutant patients, at 206 µM (corresponding to 123 µg/mL). The concentration was more than 80-times higher than the clinical concentration. RYR1 gene variants in R4645Q and W5020G were shown to be causative gene mutations for MH. Intracellular calcium in myotubes from MH patients are elevated at high concentrations of remimazolam but not at clinically used concentrations of remimazolam. Remimazolam appears to be safe to use in patients with MH.

An Overview of Schizotypal Personality Disorder: Etiology Treatment

The article summarizes and analyzes some of the previous studies on schizotypal personality disorder to explain the etiology, genetic aspect such as Catechol-O-methyltransferase (COMT which is situated on chromosome 22q11) and calcium voltage-gated channel subunit alpha1 C (CACNA1C rs1006737); environmental aspect such as risky factors affecting an unnormal brain development like and psychological trauma, and chronic stress, and the treatment (Metacognitive treatment; RuminationFocused Cognitive Behavioral Therapy; Medication treatment) of schizotypal personality disorder are also discussed. Both methods, Metacognitive treatment, and RuminationFocused Cognitive Behavioral Therapy, in their respective cases, improved symptoms in schizotypal personality disorder patients. However, although research on medication treatment shows that although some medicines, like Risperidone and Haloperidol, can also improve schizotypal personality disorder symptoms, they are also accompanied by the side effects. Moreover, the analysis shows that the present research on managing schizotypal personality disorder encounters issues such as insufficient sample size and absence of repeated experiments. These results of prior studies still need further verification before they can be used in practice.

Mechanism of Lingbao Huxin Dan in the treatment of bradyarrhythmia complicated with coronary heart disease: a network pharmacology analysis.

To investigate the mechanism of action of the Lingbao Huxin Dan in treating bradycardia arrhythmia with coronary heart disease (BA-CHD) by network pharmacology. The active ingredients of the Lingbao Huxin Dan were screened on the Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform and Bioinformatics tools designed for the analysis of molecular mechanisms of Chinese medicine platform; target prediction was conducted with the SwissTargetPrediction database, and Cytoscape 3.8 was used to construct a drug ingredient-target network. The Genecards, Online Mendelian Inheritance in Man, and DrugBank databases were searched for disease targets. Venn plots were used to display the common targets of BA-CHD and active ingredients. The STRING platform was used to construct a protein-protein interaction network. The Metascape data platform was used for Gene Ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis to construct a signaling pathway network of the active ingredients of the Lingbao Huxin Dan. There were 121 active ingredients, 899 related targets, 39 targets important in BA-CHD and 14 targets which intersected between the active ingredients and BA-CHD. There were 27 core therapeutic ingredients, 153 biological processes, 18 cell ingredients and 20 molecular functions obtained by GO enrichment analysis. The KEGG pathway analysis yielded 19 signaling pathways. RBA-CHD may treat BA-CHD by regulating adrenergic receptor beta-1, alpha 1-α adrenergic receptor, calcium voltage-gated channel subunit alpha1 C, alpha-1β-adrenergic receptor, nitric oxide synthase 2, beta-2 adrenergic receptor, voltage-dependent calcium channel subunit alpha-2/delta-1, an- giotensin-converting enzyme, Raf-1 proto-oncogene serine/threonine-protein kinase, and other targets, potentially by affecting adrenergic receptor binding and calcium channel opening, to regulate the activity of cardiomyocytes.

Calcium channel β3 subunit regulates ATP-dependent migration of dendritic cells.

Migratory dendritic cells (migDCs) continuously patrol tissues and are activated by injury and inflammation. Extracellular adenosine triphosphate (ATP) is released by damaged cells or actively secreted during inflammation and increases migDC motility. However, the underlying molecular mechanisms by which ATP accelerates migDC migration is not understood. Here, we show that migDCs can be distinguished from other DC subsets and immune cells by their expression of the voltage-gated calcium channel subunit β3 (Cavβ3; CACNB3), which exclusively facilitates ATP-dependent migration in vitro and during tissue damage in vivo. By contrast, CACNB3 does not regulate lipopolysaccharide-dependent migration. Mechanistically, CACNB3 regulates ATP-dependent inositol 1,4,5-trisphophate receptor-controlled calcium release from the endoplasmic reticulum. This, in turn, is required for ATP-mediated suppression of adhesion molecules, their detachment, and initiation of migDC migration. Thus, Cacnb3-deficient migDCs have an impaired migration after ATP exposure. In summary, we identified CACNB3 as a master regulator of ATP-dependent migDC migration that controls tissue-specific immunological responses during injury and inflammation.

Peptides derived from high voltage-gated calcium channel β subunit reduce blood pressure in rats.

The β subunits of high voltage-gated calcium channels (HGCCs) are essential for optimal channel functions such as channel gating, activation-inactivation kinetics, and trafficking to the membrane. In this study, we report for the first time the potent blood pressure-reducing effects of peptide fragments derived from the β subunits in anesthetized and non-anesthetized rats. Intravenous administration of 16-mer peptide fragments derived from the interacting regions of the β1 [cacb1(344-359)], β2 [cacb2(392-407)], β3 [cacb3(292-307)], and β4 [cacb4(333-348)] subunits with the main α-subunit of HGCC decreased arterial blood pressure in a dose-dependent manner for 5-8 min in anesthetized rats. In contrast, the peptides had no effect on the peak amplitudes of voltage-activated Ca2+ current upon their intracellular application into the acutely isolated trigeminal ganglion neurons. Further, a single mutated peptide of cacb1(344-359)-cacb1(344-359)K357R-showed consistent and potent effects and was crippled by a two-amino acid-truncation at the N-terminal or C-terminal end. By conjugating palmitic acid with the second amino acid (lysine) of cacb1(344-359)K357R (named K2-palm), we extended the blood pressure reduction to several hours without losing potency. This prolonged effect on the arterial blood pressure was also observed in non-anesthetized rats. On the other hand, the intrathecal administration of acetylated and amidated cacb1(344-359)K357R peptide did not change acute nociceptive responses induced by the intradermal formalin injection in the plantar surface of rat hindpaw. Overall, these findings will be useful for developing antihypertensives.