Effect of testosterone, its 5α-reduced metabolites and the corresponding propionates on testosterone metabolism. I—in the hypothalamus and in the anterior pituitary

Abstract

The effect of a 6-day treatment with testosterone, dihydrotestosterone, 5α-androstan-3α,17β-diol, and 5α-androstan-3β,17β-diol on testosterone metabolism measured in vitro in the hypothalamus and anterior pituitary of adult castrated male rats has been investigated. The steroids have been injected both in the free alcohol and in the propionate form at the daily dose of 2 mg/rat. In the hypothalamus the 5α-reductase and the 3-hydroxysteroid dehydrogenase are not modified by any steroid treatment. In contrast, the 17β-ol-dehydrogenase is either stimulated or inhibited, depending on the steroid administered. In the anterior pituitary both the 5α-reductase and the 3-hydroxysteroid dehydrogenase are generally inhibited by the androgen treatment. The 17β-ol-dehydrogenase is either stimulated or left unmodified, depending again on the steroid administered. In conclusion, it appears that in the two structures considered the different enzymes involved in testosterone metabolism are under separate control mechanisms.