Changes in testosterone metabolism by the brain and cloacal gland during sexual maturation in the Japanese quail (Coturnix coturnix japonica).

Testosterone metabolism in the brain and pituitary and cloacal glands of male and female Japanese quail was studied in vitro during sexual maturation (from 1 day to 5 weeks after hatching). The production of 5 alpha-dihydrotestosterone in the hyperstriatum and cloacal gland and that of androstenedione in the cloacal gland of males was highest at 1 day after hatching, which could be related to the peak of plasma androgens previously demonstrated in neonatal quail. 5 beta-Reductase activity was very high in the brain, but not the pituitary or cloacal glands of young chicks and decreased markedly, especially in the hypothalamus, during sexual maturation. As 5 beta-reduced metabolites of testosterone are inactive androgens, it is suggested that the decrease of 5 beta-reductase activity with age corresponds to a potentiation of the effects of testosterone at the level of the brain.