Adrenergic control of protein metabolism in skeletal muscle

This review summarizes evidence indicating that the sympathetic nervous system, through hormonal and neurotransmitter actions, produces anabolic, protein-sparing effects on skeletal muscle protein metabolism. Studies are reviewed which indicate that catecholamines secreted by the adrenal medulla have an inhibitory effect on muscle Ca2+-dependent protein degradation independently of other hormones. In addition, norepinephrine released from adrenergic terminals may increase the rate of protein synthesis in oxidative muscles, leading to increased protein accretion. Evidence is also presented that these effects seem to be mediated by beta(2)-adrenoceptors and cyclic adenosine monophosphate-dependent pathways, The understanding of the precise mechanisms by which endogenous catecholamines promote muscle anabolic effects may bring new perspectives for efficient treatment of muscle-wasting conditions and enhancement of growth efficacy in farm species. (C) 2002 Lippincott Williams Wilkins.