[Specific regulation by steroid hormones of adenylate cyclase in the endometrium]

Adenylate cyclase was studied in human endometrium during the menstrual cycle and in rabbit endometrium after various hormonal treatments to clarify the effects of steroid hormones on this activity. Human endometrial adenylate cyclase was more stimulated by catecholamines (L-isoproterenol and L-epinephrine) and prostaglandins (PGE2 and PGF2 alpha), than the myometrium, corpus luteum and fallopian tube. Catecholamine-stimulated adenylate cyclase activity reached a peak in the late proliferative phase and significantly decreased thereafter. Prostaglandin-stimulated activity was low during the proliferative phase and reached significantly high levels in the late secretory phase. Adenylate cyclase activity was studied in rabbit endometrium before and after the administration of hCG. Catecholamine-stimulated activity was significantly low and prostaglandin-stimulated activity was significantly high in rabbit endometrium after hCG treatment. Further, changes in adenylate cyclase activity was studied in the endometrium of ovariectomized rabbits treated with estrogen, progesterone and/or cycloheximide. The administration of estrogen caused a significant increase in catecholamine-stimulated activity but this effect was inhibited by cycloheximide. The administration of progesterone caused a significant increase in prostaglandin-stimulated activity but this effect was inhibited by cycloheximide. The results demonstrate specific changes in endometrial adenylate cyclase activity during the menstrual cycle and that these changes are regulated by estrogen and progesterone via de novo synthesis of proteins.