REGULATION OF CORPUS-LUTEUM FUNCTION IN EARLY HUMAN-PREGNANCY

Objective: To investigate the capacity of the human corpus luteum (CL) of pregnancy to form cyclic adenosine-3',5'-monophosphate (cAMP) and P in vitro in response to hCG and prostaglandin (PG) E(2). Design: Six women undergoing sterilization concomitant with legal abortion and ei ght women undergoing surgery for ectopic pregnancy were included. Huma n chorionic gonadotropin was analyzed preoperatively in two serum samp les. The CL were excised and luteal specimens were incubated for 2 hou rs in the presence or absence of hCG or PGE(2). The tissue concentrati ons of cAMP and P concentrations in the incubation media were measured . The in vitro results were correlated to the preoperative daily chang e in serum hCG. Results: In CL from pregnancies with normally rising s erum hCG levels, the addition of hCG in vitro did not affect luteal cA MP or P production. In pregnancies with plateauing and/or decreasing s erum hCG levels, the addition of hCG in vitro significantly stimulated cAMP and P formation, and this stimulatory effect correlated signific antly with the preoperative daily change in serum hCG. In contrast to hCG;, PGE(2) had the same stimulatory effect in vitro on CL specimens from both normal and pathological pregnancies. This effect did not cor relate with the preoperative daily change in serum hCG. Conclusions: P rostaglandin E(2) stimulates all CL, irrespective of any changes in pr eoperative serum hCG levels. In contrast, the stimulatory effect of hC G in vitro does correlate with changes in serum hCG, and thus CL from pregnancies with normally rising serum hCG levels are refractory to hC G in vitro.