Binding and metabolism of testosterone in the rat brain during sexual maturation—II. Testosterone metabolism

Abstract

Slices of cerebral cortex, hypothalamus, hypophysis and prostate of three- to nine-week-old male rats castrated for 24–48 h, were incubated with tritiated testosterone. Steroids were identified in the incubation medium, and in the total protein fraction from the cytosol and nuclear fluid of the incubated tissues. With the four tissues, the metabolites found in the incubation medium presented no appreciable differences in relation to age. In the hypothalamus, more 17β-hydroxy-5α-androstane-3-one bound to the cytosol proteins was found in the immature than in the adult animals, but a small quantity of this compound bound to the nuclear proteins was always present regardless of age. In the hypophysis, less testosterone and more 17β-hydroxy-5α-androstane-3-one bound to the cytosolic and nuclear proteins were found during puberty, with more nuclear than cytosolic bound 17β-hydroxy-5α-androstane-3-one. These two series of results suggest a role of this compound as the active form of testosterone in the hypophysis.