Abstract
The neuromuscular junction (NMJ) is a specialized synapse that bridges the motor neuron and the skeletal muscle fiber and is crucial for conversion of electrical impulses originating in the motor neuron to action potentials in the muscle fiber. The consideration of contributing factors to skeletal muscle injury, muscular dystrophy and sarcopenia cannot be restricted only to processes intrinsic to the muscle, as data show that these conditions incur denervation-like findings, such as fragmented NMJ morphology and corresponding functional changes in neuromuscular transmission. Primary defects in the NMJ also influence functional loss in motor neuron disease, congenital myasthenic syndromes and myasthenia gravis, resulting in skeletal muscle weakness and heightened fatigue. Such findings underscore the role that the NMJ plays in neuromuscular performance. Regardless of cause or effect, functional denervation is now an accepted consequence of sarcopenia and muscle disease. In this short review, we provide an overview of the pathologic etiology, symptoms, and therapeutic strategies related to the NMJ. In particular, we examine the role of the NMJ as a disease modifier and a potential therapeutic target in neuromuscular injury and disease.
Highlights
Tatiana Kostrominova andThe area of synaptic contact between motor neurons and their target muscle fibers is the neuromuscular junction (NMJ)
When released into the synaptic cleft, ACh binds to acetylcholine receptors (AChRs), causing an endplate potential (EPP), a local depolarization that propagates throughout the muscle fiber as a conducted action potential
In the mdx mouse, muscle weakness has been linked to the NMJ [22,38,39,40,41], and a further loss in muscle function after injury is associated with additional changes in NMJ morphology
Summary
The area of synaptic contact between motor neurons and their target muscle fibers is the neuromuscular junction (NMJ). This synapse occurs at a specialized area of the sarcolemma called the endplate (Figure 1). Interdigitated between post-junctional folds are the perisynaptic Schwann cells (PSCs), which are glial regulators of NMJ structure and function [2]. Representative confocal microscopy image potential in the muscle fiber This release of surplus and consequent excess of fluorescent with an acetylcholine receptor (α-Bungarotoxin, BTX, red). Improper development, phin and its associated glycoprotein complex (DGC), which is present throughout the muscle fiber organization and remodeling at the the NMJ can impair the reliability and efficiency of membrane, accumulate underneath post-synaptic membrane. This review examines several such impacts on NMJ structure and function in the context of muscle disease, motor neuron disease, and aging
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