Effects of Gonadal Steroids on the Secretion of LH and FSH in Neonatal Rats1

Castrated neonatal male rats (6–9 days old) were treated with testosterone propionate and estradiol benzoate. Both steroids were capable of suppressing the increases in serum LH and FSH concentrations which normally follow castration. Serum levels of both gonadotropins were decreased by 8–9 hr after the injection of either 3 μg testosterone propionate or 0.2 μg estradiol benzoate. A study was also made of the effects of exogenous steroids in intact female neonates (5–10 days old). FSH levels could be decreased by either androgen or estrogen; however, the large degree of variability in serum LH concentrations observed in control females made it difficult to draw any firm conclusion regarding the effect of steroids on LH secretion in females. (Endocrinology89:112,1971)