EFFECT OF THE URINARY INHIBITOR ON THE UTERINE WEIGHT RESPONSE TO GONADOTROPHINS

Abstract

ABSTRACT A boiled kaolin acetone extract of urine inhibited the activity of small doses of chorionic gonadotrophin (HCG), pregnant mares' serum gonadotrophin (PMS) and urinary pituitary gonadotrophin in the immature mouse uterus assay. Bigger doses of these gonadotrophins were not affected. The gonadotrophin inhibitory material (GIM) did not affect the uterine weight response to pituitary follicle-stimulating hormone (FSH) or oestrone. It was noted that the gonadotrophin inhibitory effects of GIM were very similar to the reports of inhibition of gonadotrophins in hypophysectomised animals. It was therefore postulated that GIM inhibits the endogenous gonadotrophin secretion which is necessary for the activity of certain gonadotrophins at low doses. In support of this hypothesis it was found that HCG was not inhibited by GIM if the animals were also given FSH. The conclusion that GIM acts by inhibiting endogenous gonadotrophin is contrary to the normally accepted view that GIM inhibits exogenous HCG or luteinising hormone directly.