When pregnant rats are given a single subcutaneous injection of ergocornine methanesulphonate on the 4th day of gestation, physiological indications of changes in the ovary are manifold.
Activities of a number of histochemically demonstrable enzymes were investigated in the ovaries of ergot-treated pregnant rats. The enzymes included Δ5-3β-hydroxysteroid dehydrogenase, succinic dehydrogenase, alkaline and acid phosphatase and adenosine-triphosphatase.
The ovaries were examined at 2-, 4-, 8- and 24-hr intervals after administration of the drug. Macroscopic and microscopic vascular dilatation and engorgement were seen in the ovaries at 2, 4 and 8 hr and had decreased by 24 hr. Activities of Δ5-3β-hydroxysteroid dehydrogenase and succinic dehydrogenase were histochemically demonstrable in the corpora lutea of gestation as well as other sites in the ovary at 2, 4 and 8 hr after ergocornine. At 24 hr, portions of the corpora lutea of gestation showed necrosis and dissolution of cells and many healthy vesicular follicles had developed. These changes in the ovary (luteolysis in the corpora lutea of gestation and development of follicles to the ovulation stage) form the basis for the physiological effects—interruption of gestation and appearance of oestrus—which occur 2 to 3 days after administration of ergocornine to pregnant rats during progestation.