Relationships among Progesterone, Androgen, and 0Estradiol in Corpora Lutea and Nonluteal Ovarian Compartments of Pseudopregnant Rats: Effects of Decidual Tissue*

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Abstract
Rats (200–275 g) were rendered pseudopregnant on the morning of estrus (day 1) by cervical stimulation. On day 5 of pseudopregnancy (PS), the rats (8–12/group) were subjected to either hysterectomy (HX) or unilateral or bilateral decidual cell reactions (uni- or bi-DCR). Control pseudopregnant (C-PS) rats were sham operated on day 5. On days 8 and 12, the rats were killed by decapitation. Blood was collected, and serum was saved for RIA of estradiol (E2), progesterone (P), androgen (A), and gonadotropins. Corpora lutea (CL) and the nonluteal ovarian compartment (NLO) were incubated separately in vitro for 2 h in Krebs-Ringer bicarbonate buffer, and steroid concentrations were determined in CL and NLO (before and after incubation) and in incubation media. On day 8 of PS, P and A levels in the serum in bi-DCR rats were higher than those in C-PS but not in uni-DCR and HX-PSP rats; however, on day 12, serum P and A levels in bi-DCR rats were higher than the levels of other PS groups, with the exception of C-PS rats whose serum A levels were the same as those in bi-DCR rats. No differences were observed in serum E2 levels throughout the experimental period. On days 8 and 12, the luteal P concentration of bi-DCR rats was higher than that of any other PS group, i.e. uni-DCR, HX-PS, and C-PS rats. The higher concentrations of luteal P in bi-DCR rats were associated with neither concomitant increases of luteal A and E2 nor higher serum levels of FSH, LH, and PRL, and they are therefore attributed to the large amount of decidual tissue (DT) in bi-DCR rats. In bi-DCR, uni-DCR, and HX-PS rats, no differences were observed in the luteal concentration of A on day 8 or 12; however, E2 levels in CL of all PS groups were higher on day 12 than on day 8. The reasons for that difference is unclear, but it may be related to the onset of LH dependency of these CL and, therefore, causally related to luteal maintenance. Collectively, these results indicate the possibility that DT selectively stimulates luteal P production in vivo without altering luteal A and E2, and that this effect of DT may be quantitatively related to the amount of DT. in vitro, CL of bi-DCR rats produced P, A, and E2 in quantities similar to other PS groups, with the exception of C-PS rats on day 12 whose CL were regressed and synthesized less P and more E2 than bi-DCR rats; therefore, a DCR effect on steroidogenesis in vitro was not observed. On day 12 of PS, a significant increase in in vitro A and E2 production by NLO was observed, indicating that antral follicles may become highly competent to produce A and E2 during the latter portion of PS. (Endocrinology106: 758, 1980)