Impact of testosterone and oestradiol on region specificity of skeletal muscle-ATP, creatine phosphokinase and myokinase in male and female Wistar rats

The main aim of the present study was to test the hypothesis that skeletal muscle ATP concentration, creatine phosphokinase and myokinase enzyme activ ities are stimulated by the sex steroids in both male and female rats (anim als were nor subjected to any kind of exercise or any training). To test th e hypothesis healthy mature (90-120 days old, weighing about 160-180 g) mal e and female rats were gonadectomized. Gonadectomized male and female rats were administered with testosterone (Sigma Chemical, St Louis, MO, USA) at a dose of 100 mu g (100 g body weight)(-1) day(-1) for males and 5 mu g (10 0 g body weight)(-1) day(-1) for females for 30 days from day 31 post-castr ation onwards; and oestradiol at a dose of 5 mu g (100 g body weight)(-1) d ay(-1) for 30 days from day 31 post-castration onwards for both males and f emales (17 beta oestradiol, Sigma Chemical Company, St Louis, MO, USA). The ATP content, creatine phosphokinase and myokinase enzyme activities of ske letal muscles were significantly higher than that of skeletal muscles of fe male control rats. Gonadectomy resulted in a significant decrease in ATP co ntent and creatine phosphokinase myokinase enzyme activities in both male a nd female rats. Testosterone treatment to gonadectomized male rats brought back the parameters to normalcy whereas the same to the female rats enhance d the enzyme activities and ATP contents to the level of control male rats. Oestradiol treatment to castrated male rats did nor bring about any signif icant alterations whereas the same in gonadectomized female rats brought th em back to normalcy. Therefore from the present study it is concluded that testosterone is effective in both males and females whereas oestradiol was effective only in the females in enhancing skeletal muscle energy metabolis m.