Role of ovarian steroid hormones in the regulation of adenylate cyclase during early progestation.

The hormonal regulation of uterine adenylate cyclase (AC) was measured in the rat by radiochemical analysis. Animals made pseudopregnant by cervical stimulation were ovariectomized on Day 1 (the first appearance of leukocytes in the vaginal smear) and injected for 6 days with sesame oil, 0.1-10.0 micrograms estrone, 2.0 mg progesterone, or 1.0 microgram estrone + 2.0 mg progesterone. AC activity in ovariectomized controls remained at basal levels (2.8-3.3 pmol cAMP formed/min X mg protein). The injection of progesterone did not alter AC activity significantly, but estrone increased AC activity during Days 3-5, and the response (5-17 pmol) was dose dependent. The action of estrone was not inhibited by progesterone. The present experiments revealed: a) AC from estrone-treated rats was activated 2- to 4-fold by 10 mM NaF; b) following treatment with estrone + progesterone, AC was activated 2- to 3-fold by a trauma to the uterus; c) unlike the response to fluoride, the effect of trauma was temporally limited to Day 4; and d) when AC was activated by trauma, no further increase was elicited by NaF. The data indicated that the transient sensitivity of AC to activation by trauma on Day 4 in E+P-treated rats was identical to that in intact rats and paralleled the normal timing of uterine sensitivity to decidual induction.