Regression of Spontaneous Mammary Tumors in Rats by Ergot Drugs 1

Summary Daily injection of ergocornine or ergokryptine for 4 weeks induced marked regression in growth of spontaneous mammary tumors in old female rats. After termination of drug treatment, prompt resumption of mammary tumor growth was observed. Both drugs are believed to inhibit mammary tumor growth by depressing secretion of pituitary prolactin.