Effect of steroid hormones and antihormones on hypothalamic beta-endorphin concentrations in intact and castrated female rats.
The aim of the present study was to evaluate the effects of estrogens and androgens on hypothalamic beta-endorphin (beta-EP) concentrations. Intact or castrated female rats were chronically (2 weeks) treated with estrogen (estradiol benzoate) and/or antiestrogens (clomiphene, cyclophenil or epimestrol), and with androgens (dihydrotestosterone or dehydroepiandrosterone sulphate) and/or antiandrogen (cyproterone acetate). A group of rats treated with vehicle were studied as comparison. The beta-EP concentrations were measured by radioimmunoassay on acidic extracts of rat hypothalami. The administration of clomiphene and cyclophenil significantly reduced hypothalamic beta-EP concentrations in intact rats, while both drugs or estradiol benzoate increased the peptide concentration in castrated rats. Both intact and castrated rats treated with epimestrol showed hypothalamic beta-EP concentrations higher than vehicle treated rats. The estradiol-induced increase of beta-EP was not changed by the concomitant administration of antiestrogens. The administration of dihydrotestosterone significantly decreased beta-EP concentrations in both intact and castrated female rats, while the treatment with dehydroepiandrosterone sulphate only slightly decreased beta-EP levels in intact female rats. The cyproterone acetate-chronically treated rats showed higher beta-EP concentrations than vehicle-treated rats and these changes were reversed by the concomitant addition of dihydrotestosterone or dehydroepiandrosterone sulphate. These results showed that estrogens play a positive role while androgens negatively influence the hypothalamic beta-EP concentrations in female rats, supporting the view that central beta-EP might be a target of gonadal steroid feedback signals.
Genazzani
A R
AR
Istituto Clinica Ostetrica e Ginecologica, Università di Modena, Italy.
Petraglia
F
F
Mercuri
N
N
Brilli
G
G
Genazzani
A D
AD
Bergamaschi
M
M
DeRamundo
B M
BM
Volpe
A
A
D000726:Androgen Antagonists / Q000494:pharmacology*; D000728:Androgens / Q000494:pharmacology*; D000818:Animals; D002996:Clomiphene / Q000494:pharmacology; D003506:Cyclofenil / Q000494:pharmacology; D003534:Cyproterone / Q000031:analogs & derivatives / Q000494:pharmacology; D017373:Cyproterone Acetate; D003687:Dehydroepiandrosterone / Q000031:analogs & derivatives / Q000494:pharmacology; D019314:Dehydroepiandrosterone Sulfate; D013196:Dihydrotestosterone / Q000494:pharmacology; D004836:Epimestrol / Q000494:pharmacology; D004958:Estradiol / Q000494:pharmacology*; D004965:Estrogen Antagonists / Q000494:pharmacology*; D005260:Female; D007031:Hypothalamus / Q000187:drug effects / Q000378:metabolism*; D010052:Ovariectomy; D051381:Rats; D011919:Rats, Inbred Strains; D001615:beta-Endorphin / Q000378:metabolism*
D000726:Androgen Antagonists; D000728:Androgens; D004965:Estrogen Antagonists; D013196:Dihydrotestosterone; D002996:Clomiphene; D003687:Dehydroepiandrosterone; D017373:Cyproterone Acetate; D004958:Estradiol; D019314:Dehydroepiandrosterone Sulfate; D001615:beta-Endorphin; D004836:Epimestrol; D003534:Cyproterone; D003506:Cyclofenil