THE USE OF NON-CASTRATE PARABIOTIC RATS FOR THE EVALUATION OF PLASMA GONADOTROPHINS

Abstract

ABSTRACT The gonads and accessory sex organs of hypophysectomized male or female rats were used to evaluate the gonadotrophin content of the plasma from a non-castrate parabiotic partner. Ovarian follicular development and the human chorionic gonadotrophin augmentation reaction indicated the presence of FSH in the plasma of immature males. LH was apparent by androgen production from testes in hypophysectomized male partners. The amount of LH was reduced by 2 mg progesterone or 20 μg testosterone propionate (TP) and increased by administration of hypothalamic extract daily to the intact male. Bilateral cryptorchidism also quickly elevated the plasma LH level. FSH output, as measured by follicular development in females, was not significantly affected by 50 μg TP or 2 μg oestradiol daily for 10 days. Females had little gonadotrophin in their plasma since hypophysectomized female partners showed only slight ovarian and no uterine stimulation. The increased gonadotrophins associated with unilateral compensatory hypertrophy, however, was quickly manifested in follicular hypertrophy and abundant oestrogen production in the hypophysectomized partner.