Influence of Testosterone, Estradiol-17β and Dihydrotestosterone on Circulating LH and FSH in Castrate Male Guinea Pigs

Abstract

The influence of testosterone, dihydrotestosterone, estradiol-17β or combinations of these steroids on gonadotropin regulation was examined in castrate male guinea pigs. Physiological replacement therapy with testosterone prevented the postcastration rise in LH. Treatment with dihydrotestosterone and the combination of estradiol-17β plus testosterone was also effective. In contrast, these treatments reduced but did not prevent the postcastration rise of FSH. The negative feedback effects of these steroid treatments was not altered when 3, 6 or more than 8 weeks elapsed between castration and the initiation of steroid replacement therapy. Our data indicate that the guinea pig testosterone and dihydrotestosterone are effective regulators of LH but that other hormones may be important in the regulation of FSH.