Androgens regulate mitochondrial cytochrome c oxidase and lysosomal hydrolases in mouse skeletal muscle

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Abstract
The gastrocnemius, a fast-twitch white muscle, and the soleus, a slow-twitch red muscle, were studied in A/J mice. The specific activities of the lysosomal hydrolases, .beta.-D-glucuronidase, hexosaminidase, .beta.-D-galactosidase and arylsulfatase, the inner-mitochondrial-membrane enzyme cytochrome c oxidase and the outer- mitochondrial-membrane enzyme monoamine oxidase, were greater in the soleus than in the gastrocnemius. The specific activities of the lysosomal hydrolase and cytochrome c oxidase in the gastrocnemius and soleus were substantially higher in male mice than in female mice. Orchiectomy abolished this sex difference. Testosterone increased the activities of the lysosomal hydrolases and cytochrome c oxidase, and coincidentally induced muscle hypertrophy and an accretion of protein and RNA; total DNA remained constant. Monoamine oxidase was unaffected by sex, orchiectomy and testosterone. Endogenous androgens evidently regulate the activity of enzymes associated with lysosomes and the inner mitochondrial membrane, and muscle fiber growth in mouse skeletal muscle.