Oestradiol synergizes with 5α-dihydrotestosterone or 3α- but not 3β-androstanediol in inducing sexual behaviour in castrated rats

Abstract

ABSTRACT Castrated male rats were treated with constant-release implants filled with testosterone, oestradiol-17β, 17β-hydroxy-5α-androstan-3-one (5α-dihydrotestosterone; DHT), 5α-androstane-3α,17β-diol (3α-Adiol) or 5α-androstane-3β,17β-diol (3β-Adiol). Only testosterone activated the sexual behaviour of the rats. If combined with oestradiol, DHT or 3α-Adiol induced the behaviour, but 3β-Adiol failed to have this effect. Oestradiol inhibited the in-vitro formation of [14C]Adiols from [14C]DHT by combined preoptic and hypothalamic tissue, but only when given in high doses. No effect on the formation of [14C]Adiols from [14C]DHT was found in rats treated in vivo with DHT or with the combination of DHT and oestradiol which effectively stimulated sexual behaviour. These results do not support the suggestion that oestradiol may synergize with androgens to induce sexual behaviour in castrated rats by inhibiting androgen metabolism. J. Endocr. (1988) 119,461–465