title: Neuronal involvement in muscular atrophy.
abstract: The innervation of skeletal myofibers exerts a crucial influence on the maintenance of muscle tone and normal operation. Consequently, denervated myofibers manifest atrophy, which is preceded by an increase in sarcolemma permeability. Recently, de novo expression of hemichannels (HCs) formed by connexins (Cxs) and other none selective channels, including P2X7 receptors (P2X7Rs), and transient receptor potential, sub-family V, member 2 (TRPV2) channels was demonstrated in denervated fast skeletal muscles. The denervation-induced atrophy was drastically reduced in denervated muscles deficient in Cxs 43 and 45. Nonetheless, the transduction mechanism by which the nerve represses the expression of the above mentioned non-selective channels remains unknown. The paracrine action of extracellular signaling molecules including ATP, neurotrophic factors (i.e., brain-derived neurotrophic factor (BDNF)), agrin/LDL receptor-related protein 4 (Lrp4)/muscle-specific receptor kinase (MuSK) and acetylcholine (Ach) are among the possible signals for repression for connexin expression. This review discusses the possible role of relevant factors in maintaining the normal functioning of fast skeletal muscles and suppression of connexin hemichannel expression.
authors.affiliation: Departamento de Fisiología, Pontificia Universidad Católica de Chile Santiago, Chile.
authors.forename: Bruno A
authors.initials: BA
authors.lastname: Cisterna
authors.affiliation: Center of Excellence for the Medical Consequences of Spinal Cord Injury, James J. Peters Veterans Affairs Medical Center Bronx, NY, USA ; Departments of Medicine and Rehabilitation Medicine, Icahn School of Medicine at Mount Sinai New York, NY, USA.
authors.forename: Christopher
authors.initials: C
authors.lastname: Cardozo
authors.affiliation: Departamento de Fisiología, Pontificia Universidad Católica de Chile Santiago, Chile ; Instituto Milenio, Centro Interdisciplinario de Neurociencias de Valparaíso, Universidad de Valparaíso Valparaíso, Chile.
authors.forename: Juan C
authors.initials: JC
authors.lastname: Sáez
keywords: acetylcholine; connexins; electrical activity; hemichannels; trophic factors