Effects of ACTH on the uterine weight response to HCG in mice

The effects of ACTH and dexamethasone on the uterine weight of immature mice treated with HCG or oestradiol-17 beta were studied. The animals were treated daily for 3 days and wet and dry uterine weights were measured on the 4th day. Low doses of ACTH (1-25 mug/day) raised the sensitivity of the uterine weight response to threshold doses of HCG (0-05 to 0-1 i.u.). By increasing the doses of ACTH or HCG, the stimulation gradually turned into inhibition. By itself, ACTH was ineffective and it had no influence on the increase in uterine weight induced by oestradiol-17 beta. Dexamethasone failed to stimulate the effect of HCG.