The Inhibition by Denervation of the Effect of Testosterone on Glycogen Metabolism in the Levator Ani Muscle

Findings cannot be explained with the effects of denervation per se on glycogen metabolism, but denervation shows some specificity in its interaction with testosterone effects.

Abstract

When testosterone (5 mg/day, subcutaneously) is given to castrated rats, a marked increase of the glycogen content of the levator ani muscle ensues. The rate of the glycogen synthesis is enhanced because of increase i) of the rates of sugar transport and phosphorylation, ii) of the soluble hexokinase activity, and iii) of the glycogen synthetase I activity. Also, total glycogen phosphorylase is increased. When testosterone is given to rats submitted to destruction of the spinal cord immediately before the injection of the hormone, the increase of the glycogen content is much smaller; the increase of the rate of the sugar uptake is no more apparent; the increase of sugar phosphorylation and that of the rate of glycogen synthesis are delayed; the increase of glycogen phosphorylase activity is not changed. All these findings cannot be explained with the effects of denervation per se on glycogen metabolism. Also, denervation shows some specificity in its interaction with testosterone effects. Possibly, levator ani muscle is affected by testosterone by 2 mechanisms, one of which requires involvement of the nerves. This might be a clue to explain the much higher sensitivity to androgens levator ani muscle shows in comparison to other skeletal muscles. (Endocrinology92: 667, 1973)