THE EFFECT OF ALTERATIONS IN ADRENOCORTICAL FUNCTION ON THE MOUSE UTERINE WEIGHT RESPONSE TO HUMAN CHORIONIC GONADOTROPHIN

ABSTRACT The activity of human chorionic gonadotrophin (HCG) in the mouse uterus assay depends on the secretion of endogenous gonadotrophin. This source of gonadotrophin is suppressed when the animals are starved or injected with toxic substances, and the response to HCG is therefore inhibited. There is good evidence that this is the mode of action of the urinary gonadotrophin inhibitor (GIM). Since it has been claimed that stress-induced inhibition of gonadotrophin secretion is related to alterations in adrenocortical function, the present investigation is concerned with the response to HCG in animals with experimental hyper- and hypoadrenocorticalism. ACTH gel (300 mU) and a depot form of synthetic ACTH (15 μg) augmented the uterine weight response to HCG (0.5 IU). Normal responses were obtained in animals treated with HCG and either cortisol (300 μg), corticosterone (300 μg) or dehydroepiandrosterone (300 μg). Bilateral adrenalectomy produced similar effects to those previously described for GIM and stressful stimuli, namely, inhibition of HCG activity but no impairment of the responses to follicle-stimulating hormone (FSH), HCG given with FSH, or oestrone. It was thought that these results were produced by the metabolic and traumatic effects of the operation rather than by increased secretion of ACTH per se. Cortisol, corticosterone and ACTH gel did not influence the effect of GIM on HCG activity in the mouse uterus assay. The results suggest that suppression of endogenous gonadotrophin secretion following acute stress is not secondary to increased secretion of ACTH or hyperfunction of the adrenal cortex.