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

Abstract

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