A phorbol ester and calcium ionophore regulate sex steroid and prostaglandin release by follicles of the anuran Rana esculenta and the urodele Triturus carnifex.

The aim of this work was to study the relationships among protein kinase C (PKC), calcium, prostaglandins (PGs), and sex steroids in follicles of Rana esculenta and Triturus carnifex. Follicles, oocytes, and wall cells of follicle (theca and granulosa cells) were incubated in vitro with an activator of PKC, phorbol-12-myristate-13-acetate (PMA), a calcium ionophore (A23187), an antagonist of calcium channel, verapamil, PMA + A23187, prostaglandin F2 alpha (PGF2 alpha), and prostaglandin E2 (PGE2). Progesterone, androgens, and 17 beta-estradiol were assessed in incubation media of follicles and wall cells and PGs in incubation media of follicles, oocytes, and wall cells. In both species, PMA increased progesterone; A23187 increased progesterone, 17 beta-estradiol, and PGs; verapamil decreased progesterone and PGs; PMA + A23187 increased progesterone, 17 beta-estradiol, and PGs; PGF2 alpha increased 17 beta-estradiol; PGE2 increased progesterone. These data suggest that PKC and calcium intervene in the regulation of steroidogenesis and PG synthesis by follicles of both R. esculenta and T. carnifex; in particular, calcium seems to regulate PGs synthesis, activating an enzymatic pathway which does not include PKC.