title: Activation of sexual behaviour in castrated rats: the role of oestradiol.
abstract: Sexual behaviour was induced in castrated male rats with oestradiol-17 beta- or testosterone-filled constant-release implants. Testosterone-induced sexual behaviour was unaffected by treatment with the 5 alpha-reductase inhibitor 17 beta-N,N-diethylcarbamoyl-4-aza-5 alpha-androstan-3-one (4-MA; 16.7 mg/day) but treatment with the aromatization inhibitor 1,4,6-androstatriene-3,17-dione (ATD; 10 mg/day) prevented testosterone from inducing the behaviour. Sexual behaviour could be activated in castrated rats treated with testosterone plus ATD by treatment with 4-MA or with implants filled with a low dose of oestradiol. Lordosis behaviour induced in ovariectomized rats with testosterone-filled implants and progesterone was blocked by ATD treatment and could not be activated with 4-MA but oestradiol implants restored the display of lordosis in the testosterone plus ATD-treated females. 4-MA inhibited the in-vitro formation of [14C]5 alpha-dihydrotestosterone from [14C]testosterone by combined preoptic and hypothalamic tissue at all doses tested and a high dose of oestradiol exerted a similar effect. The results suggest that androgen aromatization is required for testosterone-activated female sexual behaviour but not for testosterone-activated male sexual behaviour. It is suggested that oestradiol normally acts to control the sexual behaviour of male rats by modifying neural androgen metabolism.
mesh_terms: D000728:Androgens / Q000097:blood; D000733:Androstatrienes / Q000494:pharmacology; D000818:Animals; D001378:Azasteroids / Q000494:pharmacology; D013196:Dihydrotestosterone / Q000031:analogs & derivatives / Q000494:pharmacology; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D007031:Hypothalamus / Q000187:drug effects; D008297:Male; D009919:Orchiectomy; D010052:Ovariectomy; D011187:Posture; D051381:Rats; D011919:Rats, Inbred Strains; D012726:Sexual Behavior, Animal / Q000187:drug effects*; D013739:Testosterone / Q000378:metabolism / Q000494:pharmacology
chemical_list: D000728:Androgens; D000733:Androstatrienes; D001378:Azasteroids; D013196:Dihydrotestosterone; C011658:androsta-1,4,6-triene-3,17-dione; D013739:Testosterone; D004958:Estradiol; C031563:17-N,N-diethylcarbamoyl-4-methyl-4-azaandrostane-3-one