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Testosterone-induce changes in muscle mass and signaling in sedentary and voluntary-running mice

Ibebunjo, Chikwendu, Eash, John, Li, Christine, Ma, Qicheng and Glass, David (2010) Testosterone-induce changes in muscle mass and signaling in sedentary and voluntary-running mice. American Journal of Physiology Endocrinology and Metabolism, 300 (2). E327-E340. ISSN 0193-1849

Abstract

Declines in skeletal muscle size and strength, often seen with chronic wasting diseases, prolonged or high-dose glucocorticoid therapy, and the natural aging process in
mammals, are usually associated with reduced physical activity and testosterone levels. However, it is not clear whether the decline in testosterone and activity are causally related. Using a mouse model, we found that removal of endogenous testosterone by orchidectomy
results in an almost complete cessation in voluntary wheel running but only a small decline in muscle mass. Testosterone replacement restored running behavior and muscle mass to normal levels. Orchidectomy also suppressed the IGF-I/Akt pathway, activated the atrophy inducing E3 ligases MuRF1 and MAFBx, and suppressed several energy metabolism pathways, and all of these effects were reversed by testosterone replacement. The study also delineated a distinct, previously unidentified set of genes that is inversely regulated by orchidectomy and testosterone treatment. These data demonstrate the necessity of testosterone for both speed and endurance of voluntary wheel running in mice and suggest a potential mechanism for declined activity in humans where androgens are deficient.

Item Type: Article
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Date Deposited: 13 Oct 2015 13:16
Last Modified: 13 Oct 2015 13:16
URI: https://oak.novartis.com/id/eprint/2495

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