EFFECT OF TESTOSTERONE ON GLYCOGEN METABOLISM IN RAT LEVATOR ANI MUSCLE

Levator ani muscle glycogen levels fal rapidly after castration. Levels increase rapidly and considerably following the administration of testosterone, as a result of increased glycogen synthesis. This latter increase is a accompanied by increase in 2-deoxyglucose penetration and phosphorylation, and in xylose penetration. Testosterone also rapidly normalize the post-castration drop in Glc-6-P and Glc-1-P concentration levels. Investigation of enzyme activities involved in glycogen synthesis (hexokinase (EC 2.7.1.1.), phosphoglucomutase (EC 2.7.5.1.), UDPG pyrophosphorylae (EC 2.7.7.9) and Glc-6-P-dependent and -independent glycogen synthetase (EC 2.4.1.11)) revealed increased hexokinase and Glc-6-P-independent glycogen synthetase activity. Muscle glycogen synthesis response to testosterone occurs after an irreducible time lag of 6 h. The administration of actinomycin D and puromycin indicated that increased glycogen synthesis is dependent upon protein synthesis. Our data suggest that increased glycogen synthesis can be attributed to the greater penetration and more rapid phosphorylation of glucose, and also to increased Glc-6-P0independent glycogen-synthetase activity. © 1969.