RELEASE OF A PROLACTIN-LIKE SUBSTANCE BY BOVINE GRANULOSA-CELLS IN-VITRO - EFFECTS OF OVARIAN-STEROIDS

The time-dependant accumulation of prolactin (PRL) immunoreactivity in serum-free and in serum-supplemented cultures of bovine granulosa cel ls was observed. Blockade of endogenous progesterone by specific antis erum had no significant influence an PRL immunoreactivity, but progest erone addition (10-10.000 ng/ml) lead to a dose-dependent decrease. An tisera against testosterone and against estradiol-17 beta were inhibit ors, and additions of these hormones (100-10 000 ng/ml) stimulated the release of PRL immunoreactivity. The results obtained suggest the sec retion of a PRL-like peptide by bovine ovarian cells. Growth hormone, testosterone and estradiol may be stimulators, and progesterone a poss ible inhibitor of this process.