The effects of ergocornine and ergocryptine on growth of 7,12-dimethylbenzanthracene-induced mammary tumors were investigated in female Sprague-Dawley rats. Sixty-eight rats with tumors were divided into 5 groups, and 3 groups were given s.c. injections every day for 4 weeks with ergocornine or ergocryptine; 1 intact and 1 ovariectomized group served as controls. The intact controls showed a significant increase in number and size of tumors throughout the treatment period, whereas ergocornine produced a significant reduction in number and size of tumors, paralleling the effects seen in the ovariectomized controls. Ergocryptine suppressed mammary tumor growth throughout the treatment period but produced no significant decrease in number and size of tumors. When ergocornine treatment was terminated at the end of 4 weeks, prompt renewal of mammary tumor growth was observed. Inhibition of mammary tumor growth in rats by these drugs is believed to be due to their demonstrated suppression of pituitary prolactin secretion.

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Reported at the annual meeting of the American Association for Cancer Research, Chicago, Ill., April 1971.

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