Modification of body composition by clenbuterol in normal and dystrophic (mdx) mice.

Female dystrophic mice (mdx on C57 Black background) gained weight more rapidly than age-matched controls and had a higher body fat content (% body weight), a slightly lower protein content and a reduced mass of muscle. Chronic treatment (21 d) of the mice with the beta 2-agonist clenbuterol stimulated weight gain in both genotypes without affecting energy intake. Clenbuterol increased the mass of the gastrocnemius and soleus muscle by 13% and 29% in normal and dystrophic mice, respectively, and raised body protein but depressed body fat. Body water and energy content were unaffected by clenbuterol, but the ratio of protein to fat in the carcasses was enhanced by 17% in normal and 56% in dystrophic mice following clenbuterol treatment. Thus, the beta 2-agonist restored the body composition of dystrophic mice to normal and enhanced the protein to fat ratio in both these and normal mice.