Effect of ergocornine on prolactin secretion by hypophysial homografts

Hypophysial homografts equivalent to ½ or ½ of a pituitary gland were transplanted to the kidney of female rats 7 days after hypophysectomy. When examined 7 days after transplantation, the persistent nonfunctional corpora lutea (CL) had undergone structural luteolysis, presumably due to endogenous prolactin. Both ovarian weight and the weight of dissected CL were reduced by the secretions of the hypophysial homograft. Administration of ergocornine to hypophysectomized rats with sham homografts did not affect the nonfunctional CL, nor did the compound affect the ability of injected prolactin to cause structural luteolysis. Continuous ergocornine treatment (0.5 mg/day) of hypophysectomized rats bearing hypophysial homografts prevented the usual structural luteolysis, presumably by inhibiting prolactin release. These results indicate that ergocornine acts directly on pituitary cells to prevent prolactin release. This action is compatible with the proven ability of the compound to inhibit functional CL and pregnancy. (Endocrinology88: 445, 1971)