Format

Send to

Choose Destination
J Neuroendocrinol. 1991 Apr 1;3(2):221-6. doi: 10.1111/j.1365-2826.1991.tb00266.x.

Inhibition of hypothalamic aromatase activity by 5 Beta-dihydrotestosterone.

Author information

1
MRC Neuroendocrine Development and Behaviour Group, Institute of Animal Physiology, Babraham, Cambridge CB24AT, UK.

Abstract

A variable amount of circulating testosterone that reaches brain cells is converted to biologically inactive 5beta-reduced metabolites, namely, 5beta-dihydrotestosterone (5beta-DHT) and 5beta-androstane-3alpha,17beta-diol (5beta,3alpha-diol). In avian species, the production of inactive 5beta-DHT and 5beta,3alpha-diol is highest during embryonic and post-hatching life. In the present study, we have investigated the possibility that 5beta-reduction may not only correspond to a steroid inactivation pathway, but that 5beta-reduced metabolites of testosterone may exert direct inhibitory effects on enzymatic pathways producing biologically active steroids. When added to hypothalamic homogen-ates prepared from adult male doves, 5beta-DHT but not 5beta,3alpha-diol inhibits the activity of the aromatase enzyme, which converts testosterone to 17beta-oestradiol. During the first days after hatching, when the production of 5beta-reduced metabolites is high, the hypothalamic aromatase is also inhibited by 5beta-DHT. We conclude that a high 5beta-reductase activity during sensitive periods for sexual differentiation may protect the avian brain from the differentiating effects of circulating androgens by inhibiting the production of oestrogen.

Supplemental Content

Full text links

Icon for Wiley
Loading ...
Support Center