Luteinization of Transplanted Ovarian Follicles in the Rat Induced by Dibutyryl Cyclic AMP1

Abstract
The ability of dibutyryl cyclic AMP (DBC) to induce luteinization of ovarian follicles was tested using a combined in vitro—in vivo approach. Follicles from normally—cycling rats in diestrus were incubated with 7 mM DBC ± theophylline, with 10 M—g/ml luteinizing hormone (LH), or alone in Krebs—Ringer bicarbonate buffer plus glucose for 2 or 2I/2 hr. Follicles were then transplanted to hypophysectomized recipients, with DBC—exposed follicles placed under one kidney capsule and those incubated with LH or buffer only under the other capsule. As determined at autopsy 5 days after transplantation, follicles exposed to DBC or LH formed corpora lutea, but control follicles regressed; these findings were confirmed by histological examination. Progesterone secretion was assessed by testing the ability of grafts to inhibit accumulation of uterine lumen fluid in response to 17β–estradiol administration. Grafts exposed to DBC showed a significant decrease in fluid accumulation, indicative of progesterone secretion, only in rats receiving in vivo prolactin injections; other control groups showed fluid retention. Analysis of progestin contents of grafts showed that prolactin administration increased the progesterone content of DBC– and LH–exposed transplants but did not affect the content of 20a—hydroxy—pregn–4–en–3–one. These results demonstrate that dibutyryl cyclic AMP can act directly on follicles to initiate luteinization in rats and suggest that cyclic AMP may be involved in the luteinizing action of LH. (Endocrinology92: 840, 1973)

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