Muscle mass maintenance

Clemmons, D.R., 2009. Role of IGF-I in skeletal muscle mass maintenance. Trends Endocrinol Metab. 20, 349-356. Cohen, P., C. Zhao, X. Cai, J.M. Montez, S.C. Rohani, P. Feinstein, P. Mombaerts, and J.M. Friedman, 2001. Selective deletion of leptin receptor in neurons leads to obesity. J Clin Invest. 108, 1113-1121. 

Actions Enhances development and maintenance of male sex organs, sperm production, muscle mass, libido, and other secondary sex characteristics. 

Androgens are a group of Cit, steroids (Figure 53-2) that cause masculinization of the genital tract and the development and maintenance of male secondary sex characteris-tics. They also contribute to muscle bulk, bone mass, libido, and sexual performance in men. Testosterone is the main androgen secreted by the Leydig cells of the testes, and its production increases during puberty. Women produce about 5% to 10% as much testosterone as do men. 

---