Irreversible Neonatal Differentiation of Corticosterone Metabolism in Rats in vivo

The excretion of corticosterone metabolities in bile from gonadectomized male and female rats was studied; the effects of testosterone propionate treatment on steroid excretion in intact and castrated female rats were also studied. Postpubertal ovariectomy did not change the female biliary corticosteroid pattern (mainly characterized by excretion of mono and disulphurylated 3α,11β,15α,21 tetrahydroxy 5α pregnan 20 one); likewise postpubertal testectomy or even testectomy of rats 14 days of age did not change the male biliary corticosteroid pattern (mainly characterized by disulphurylated 3β,11β,21 trihydroxy 5α pregnan 20 one and 5α pregnane 3β,11β,20β,21 tetrol). On the other hand neonatal testectomy led to a feminized biliary corticosteroid pattern in the adult rats. The results indicate an irreversible suppression of the hepatic 15α hydroxylase activity by testicular secretion products, presumably androgen(s), in the neonatal period. When adult intact or gonadectomized female rats were treated with testosterone propionate the female biliary corticosteroid pattern changed to a male pattern but reverted to a female pattern some time after the therapy was stopped. These results indicate that the 15α hydroxylase activity in female rats may be reversibly suppressed by androgen treatment postpubertally.