Pathogenic Cav3.2 channel mutation in a child with primary generalized epilepsy.

Two paternally-inherited missense variants in CACNA1H were identified and characterized in a 6-year-old child with generalized epilepsy. Febrile and unprovoked seizures were present in this child. Both variants were expressed in cis or isolation using human recombinant Cav3.2 calcium channels in tsA-201 cells. Whole-cell patch-clamp recordings indicated that one variant (c.3844C > T; p.R1282W) caused a significant increase in current density consistent with a pathogenic gain-of-function phenotype; while the other cis-related variant (c.5294C > T; p.A1765V) had a benign profile

Lack of Dystrophin Affects Bronchial Epithelium in mdx Mice

Mild exercise training may positively affect the course of Duchenne Muscular Dystrophy (DMD). Training causes mild bronchial epithelial injury in both humans and mice, but no study assessed the effects of exercise in mdx mice, a well known model of DMD. The airway epithelium was examined in mdx (C57BL/10ScSn-Dmdmdx) mice, and in wild type (WT, C57BL/10ScSc) mice either under sedentary conditions (mdx-SD, WT-SD) or during mild exercise training (mdx-EX, WT-EX). At baseline, and after 30 and 45 days of training (5 d/wk for 6 weeks), epithelial morphology and markers of regeneration, apoptosis, and cellular stress were assessed. The number of goblet cells in bronchial epithelium was much lower in mdx than in WT mice under all conditions. At 30 days, epithelial regeneration (PCNA positive cells) was higher in EX than SD animals in both groups; however, at 45 days, epithelial regeneration decreased in mdx mice irrespective of training, and the percentage of apoptotic (TUNEL positive) cells was higher in mdx-EX than in WT-EX mice. Epithelial expression of HSP60 (marker of stress) progressively decreased, and inversely correlated with epithelial apoptosis (r=-0.66, P=0.01) only in mdx mice. Lack of dystrophin in mdx mice appears associated with defective epithelial differentiation, and transient epithelial regeneration during mild exercise training. Hence, lack of dystrophin might impair repair in bronchial epithelium, with potential clinical consequences in DMD patients

Mechanisms Responsible for omega-Pore Currents in Ca-v Calcium Channel Voltage-Sensing Domains

Mutations of positively charged amino acids in the S4 transmembrane segment of a voltage-gated ion channel form ion-conducting pathways through the voltage-sensing domain, named ω-current. Here, we used structure modeling and MD simulations to predict pathogenic ω-currents in CaV1.1 and CaV1.3 Ca2+ channels bearing several S4 charge mutations. Our modeling predicts that mutations of CaV1.1-R1 (R528H/G, R897S) or CaV1.1-R2 (R900S, R1239H) linked to hypokalemic periodic paralysis type 1 and of CaV1.3-R3 (R990H) identified in aldosterone-producing adenomas conducts ω-currents in resting state, but not during voltage-sensing domain activation. The mechanism responsible for the ω-current and its amplitude depend on the number of charges in S4, the position of the mutated S4 charge and countercharges, and the nature of the replacing amino acid. Functional characterization validates the modeling prediction showing that CaV1.3-R990H channels conduct ω-currents at hyperpolarizing potentials, but not upon membrane depolarization compared with wild-type channels

Analgesic effects of antidepressants alone and after their local co-administration with morphine in a rat model of neuropathic pain

Background The therapy of neuropathic pain may include the use of co-analgesics, such as antidepressants, however, their desired analgesic effect is associated with significant side effects. An alternative approach to this is their local administration which has been proposed, but there is little data regarding their local co-administration with morphine and the nature of the interaction between morphine and either doxepin or venlafaxine, two antidepressant drugs that have been recently used in neuropathic pain therapies. Methods This study was performed on rats after chronic constriction injury (CCI) to the sciatic nerve. The von Frey and Hargreaves’ tests were used to assess mechanical allodynia and thermal hyperalgesia, respectively, after intraplantar (ipl) or subcutaneous (sc) administration of amitriptyline, doxepin, or venlafaxine, or their ipl co-administration with morphine on day 12–16 after injury. Results The ipl administration of amitriptyline (3, 15 mg), doxepin (1, 5, 10, 15 mg), or venlafaxine (2, 7 mg) was effective in antagonizing CCI-induced allodynia. Their sc injection at a site distal to the injured side, did not induce alterations in pain thresholds, which supports the local mode of action. Of the three antidepressants used in this study, only ipl co-administration of amitriptyline with morphine significantly enhanced its effect in contrast to doxepin and venlafaxine, both of which weakened the analgesic effect of morphine. Conclusions In summary, the results suggest that when amitriptyline (but not doxepin or venlafaxine) is locally co-administered with morphine the effectiveness under neuropathic pain is enhanced, although additional studies are necessary to explain differential mechanisms of interaction of antidepressant drugs with morphine after local administration

The mechanism of functional up-regulation of P2X3 receptors of trigeminal sensory neurons in a genetic mouse model of Familial Hemiplegic Migraine type 1 (FHM-1)

A knock-in (KI) mouse model of FHM-1 expressing the R192Q missense mutation of the Cacna1a gene coding for the \u3b11 subunit of CaV2.1 channels shows, at the level of the trigeminal ganglion, selective functional up-regulation of ATP -gated P2X3 receptors of sensory neurons that convey nociceptive signals to the brainstem. Why P2X3 receptors are constitutively more responsive, however, remains unclear as their membrane expression and TRPV1 nociceptor activity are the same as in wildtype (WT) neurons. Using primary cultures of WT or KI trigeminal ganglia, we investigated whether soluble compounds that may contribute to initiating (or maintaining) migraine attacks, such as TNF\u3b1, CGRP, and BDNF, might be responsible for increasing P2X3 receptor responses. Exogenous application of TNF\u3b1 potentiated P2X3 receptor-mediated currents of WT but not of KI neurons, most of which expressed both the P2X3 receptor and the TNF\u3b1 receptor TNFR2. However, sustained TNF\u3b1 neutralization failed to change WT or KI P2X3 receptor currents. This suggests that endogenous TNF\u3b1 does not regulate P2X3 receptor responses. Nonetheless, on cultures made from both genotypes, exogenous TNF\u3b1 enhanced TRPV1 receptor-mediated currents expressed by a few neurons, suggesting transient amplification of TRPV1 nociceptor responses. CGRP increased P2X3 receptor currents only in WT cultures, although prolonged CGRP receptor antagonism or BDNF neutralization reduced KI currents to WT levels. Our data suggest that, in KI trigeminal ganglion cultures, constitutive up-regulation of P2X3 receptors probably is already maximal and is apparently contributed by basal CGRP and BDNF levels, thereby rendering these neurons more responsive to extracellular ATP. \ua9 2013 Hullugundi et al

Differential Requirement for Utrophin in the Induced Pluripotent Stem Cell Correction of Muscle versus Fat in Muscular Dystrophy Mice

Duchenne muscular dystrophy (DMD) is an incurable degenerative muscle disorder. We injected WT mouse induced pluripotent stem cells (iPSCs) into mdx and mdx∶utrophin mutant blastocysts, which are predisposed to develop DMD with an increasing degree of severity (mdx <<< mdx∶utrophin). In mdx chimeras, iPSC-dystrophin was supplied to the muscle sarcolemma to effect corrections at morphological and functional levels. Dystrobrevin was observed in dystrophin-positive and, at a lesser extent, utrophin-positive areas. In the mdx∶utrophin mutant chimeras, although iPSC-dystrophin was also supplied to the muscle sarcolemma, mice still displayed poor skeletal muscle histopathology, and negligible levels of dystrobrevin in dystrophin- and utrophin-negative areas. Not only dystrophin-expressing tissues are affected by iPSCs. Mdx and mdx∶utrophin mice have reduced fat/body weight ratio, but iPSC injection normalized this parameter in both mdx and mdx∶utrophin chimeras, despite the fact that utrophin was compromised in the mdx∶utrophin chimeric fat. The results suggest that the presence of utrophin is required for the iPSC-corrections in skeletal muscle. Furthermore, the results highlight a potential (utrophin-independent) non-cell autonomous role for iPSC-dystrophin in the corrections of non-muscle tissue like fat, which is intimately related to the muscle