The transformation of testosterone into dihydrotestosterone by the brain and the anterior pituitary

The ability to transform testosterone into DHT is much higher in all structures examined (with the exception of the prostate) in prepuberal than in adult rats.

Abstract

Slices of rat pituitary gland, hypothalamus, amygdala, cerebral cortex and prostate have been incubated in vitro with labelled testosterone; the metabolites formed have been identified. Testosterone is convened into 17β-hydroxy-5α-androstan-3-one (androstanolone, dihydrotestosterone, DHT) by all tissues examined. The prostate is the structure which effects such a conversion to the greatest extent; the pituitary gland and the hypothalamus are also very active; the cerebral cortex and the amygdala are also able to transform testosterone into DHT, but the rate of conversion is not as great as that found in the tissues previously mentioned. Androstenedione, 5α-androstan-3, 17-dione and 5α-androstan-3α, 17β-diol are also formed by some of the tissues. Castration increases and treatment with exogenous testosterone decreases the transformation of testosterone into DHT at the pituitary and the hypothalamic level. Both at the hypothalamic and the pituitary level, the addition in vitro of progesterone, 11-deoxycorticosterone, 11-deoxycortisol and corticosterone reduces the transformation of testosterone into DHT; on the contrary, the addition of pituitary FSH increases the conversion of testosterone into its ‘active’ metabolite. The ability to transform testosterone into DHT is much higher in all structures examined (with the exception of the prostate) in prepuberal than in adult rats.