Inhibitory Effect of Charcoal-Treated Aqueous Porcine Corpus Luteum Extract upon Ovulation in the Rabbit 1

Abstract

Administration of charcoal-treated aqueous extract of porcine corpus luteum on Days 0, 1, and 2 after mating inhibited coitus-induced ovulation in the rabbit. Inhibition of ovulation was evidenced by a significant (P < 0.01) inhibition of the coitus-induced rise in serum progesterone and lack of formation of corpora lutea. Administration of charcoal-treated heart or lung extract had no significant effect upon the formation of corpora lutea or on the coitus-induced rise in serum progesterone. Administration of the same extract 3 and 4 days after coitus-induced ovulation had no significant effect upon serum progesterone and further formation of corpora lutea. These data are consistent with the existence of an LH binding inhibitor in porcine corpus luteum extract which acts to inhibit the ovulatory response to the coitus-induced LH surge.