Treatment of ewes with a combination of CB-154 and anti-prolactin serum did not influence either blood flow to the luteal ovary or systemic levels of progesterone. It was demonstrated in this study that CB-154 treatment was followed by a dramatic decline in serum levels of prolactin. In addition, an excess of antibodies against prolactin was demonstrated in sera collected from treated ewes. It was also demonstrated that the antibodies in serum were capable of binding prolactin. Treatment of ewes during mid-cycle with anti-LH serum resulted in a rapid decline in blood flow to the luteal ovary and in circulating levels of progesterone. Infusion of exogenous LH resulted in a dramatic increase in serum levels of progesterone associated with a less dramatic increase in blood flow to the luteal ovary.
When ewes were administered PGF2α or analogs of PGF2α serum levels of progesterone and blood flow to the luteal ovary declined to basal levels within 6 h. The hemodynamic changes associated with luteal regression in PGF2α-treated ewes were similar to those observed in cycling ewes.