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Journal of Biomedicine and Biotechnology
Volume 2011 (2011), Article ID 729598, 10 pages
http://dx.doi.org/10.1155/2011/729598
Review Article

Muscle Plasticity and -Adrenergic Receptors: Adaptive Responses of -Adrenergic Receptor Expression to Muscle Hypertrophy and Atrophy

1Laboratory of Physiological Sciences, Faculty of Human Sciences, Waseda University, 2-579-15 Mikajima, Tokorozawa, Saitama 359-1192, Japan
2Japan Society for the Promotion of Science, 8 Ichiban-cho, Chiyoda-ku, Tokyo 102-8472, Japan
3Department of Natural and Living Sciences, Graduate School of Education, Joetsu University of Education, 1 Yamayashiki, Joetsu, Niigata 943-8512, Japan
4Global COE Doctoral Program, Graduate School of Sport Sciences, Waseda University, 2-579-15 Mikajima, Tokorozawa, Saitama 359-1192, Japan

Received 1 June 2011; Accepted 23 August 2011

Academic Editor: Guy Benian

Copyright © 2011 Shogo Sato et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

We discuss the functional roles of -adrenergic receptors in skeletal muscle hypertrophy and atrophy as well as the adaptive responses of -adrenergic receptor expression to anabolic and catabolic conditions. -Adrenergic receptor stimulation using anabolic drugs increases muscle mass by promoting muscle protein synthesis and/or attenuating protein degradation. These effects are prevented by the downregulation of the receptor. Endurance training improves oxidative performance partly by increasing -adrenergic receptor density in exercise-recruited slow-twitch muscles. However, excessive stimulation of -adrenergic receptors negates their beneficial effects. Although the preventive effects of -adrenergic receptor stimulation on atrophy induced by muscle disuse and catabolic hormones or drugs are observed, these catabolic conditions decrease -adrenergic receptor expression in slow-twitch muscles. These findings present evidence against the use of -adrenergic agonists in therapy for muscle wasting and weakness. Thus, -adrenergic receptors in the skeletal muscles play an important physiological role in the regulation of protein and energy balance.