The ability of
testosterone,
androsterone, 5alpha-androstane-3alpha,17beta-diol, and 5alpha-androstane-3beta,17beta-diol to prevent the
castration-induced rise in serum
gonadotropin levels was investigated in immature male rats. Rats castrated at 30 days of age were treated once per day by
subcutaneous injection of 12.5-100 mug of the
steroid per 100 g
body weight per day for 3 days, beginning on the day of
castration. The animals were sacrificed 24 h after the last injection.
Testosterone propionate,
androsterone propionate, and
5alpha-androstane-3alpha,17beta-diol dipropionate were also tested at the approximate molar equivalent of 100 mug of the free alcohol form per 100 g
body weight per day.
Testosterone propionate and 5alpha-androstane-3alpha,17beta-diol were the only compounds tested that prevented the
castration induced rise in
luteinizing hormone (LH) concentrations.
Testosterone propionate also inhibited the rise in
follicle stimulating hormone (FSH) concentrations whereas 5alpha-androstane-3alpha,17beta-diol inhibited the rise in FSH in one but not in another experiment. These were the only compounds tested that affected serum FSH concentrations. The lower doses of
testosterone tested significantly increased serum LH, but not FSH concentrations compared to castrate control animals. The highest dose tested partially inhibited the rise in serum LH concentrations. Both
androsterone and
androsterone propionate maintained ventral prostate weights. Although neither compound prevented the
castration induced rise in serum LH, two groups receiving
androsterone had serum LH concentrations significantly lower than the castrate control group. 5alpha-Androstane-3beta,17beta-diol and
5alpha-androstane-3alpha,17beta-diol dipropionate failed to maintain ventral prostate weights or prevent the rise in serum
gonadotropin levels. These results indicate that 5alpha-androstane-3alpha,17beta-diol is capable of preventing the
castration induced rise in serum LH concentrations in the immature male rat and thus may participate in the regulation of LH secretion in these animals.