About this Research Topic
Muscular dystrophies are a heterogeneous group of genetic muscle diseases characterized by muscle weakness and atrophy. Myocardial disease, manifesting predominantly as cardiomyopathy and congestive heart failure or conduction system abnormalities that cause arrhythmias, heart block, and sudden cardiac death have been observed in limb girdle type 1B, myotonic, Emery-Dreifuss, and X-linked muscular dystrophies. Experimental evidence of an association between vulnerability to lethal arrhythmias and signs of either increased sympathetic or reduced parasympathetic tone has initiated efforts to determine quantitative markers of autonomic activity in neuromuscular diseases.
Aberrant autonomic signaling is being increasingly recognized as an important symptom in a variety of clinically defined neuromuscular disorders. Heart rate variability, as a quantitative marker of parasympathetic tone, is attenuated in patients with Duchenne, Becker and myotonic muscular dystrophies. The importance of sympathovagal balance has been emphasized in various cardiovascular diseases. Treatment with a combination therapy of angiotensin-converting enzyme inhibitor and beta-blockers has been shown to be effective in reducing symptoms of congestive heart failure in patients with duchenne muscular dystrophy. However, cardiac involvement can often develop without obvious clinical symptoms in some neuromuscular diseases. Therefore, early detection and management of cardiac dysfunction is crucial because earlier treatment may be more effective for preventing later development of cardiac fibrosis. Recent animal studies have demonstrated evidence of autonomic dysregulation of cardiac rhythm in neonatal hamsters (model of muscular dystrophy), with implications that adult dystrophic phenotype could originate in utero. Therefore, autonomic dysfunction might be a causative factor in the etiology of skeletal and cardiac muscle disease. To what extent unabated sympathetic overdrive commencing early in life contributes to the eventual demise of skeletal and cardiac muscle remains to be determined. Pharmacological interventions in animal models, e.g. corticosteroids, angiotensin II type 1 receptor antagonist losartan and anti-fibrotic drugs have yielded promising results in muscular dystrophy. Abnormalities in plasma levels of atrial natriuretic peptide and norepinephrine have been demonstrated in muscular dystrophy and spinal muscular atrophy.
This research topic in Frontiers in Integrative Physiology calls for papers in any aspect of autonomic and neurohumoral regulatory mechanisms involved in muscular dystrophy – including blood pressure regulation, sensors and sensorimotor signaling, exercise pressor reflexes and molecular pathways. Studies performed in a variety of experimental models including animals and humans, cell culture, electrophysiology, molecular and genetic approaches etc will be considered. Our aim is to review, discuss, and identify autonomic regulatory mechanisms and translational approaches that are involved in the pathogenesis of muscular dystrophy.
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