Abstract
Summary
Mammary tumors were induced in Sprague-Dawley rats by a single intravenous injection of 7,12-dimethylbenz (a)anthracene. After these tumors reached about 1 cm in diameter, the rats were injected for 15 days with ergocornine or for 25 days with iproniazid or dopamine. Erogocornine and iproniazid completely suppressed mammary tumor growth and prevented development of new tumors, whereas in the control and dopamine-treated rats, growth of initial tumors increased by about 59-102% and total number of tumors about doubled. Radioimmunoassays revealed that ergocornine significantly reduced serum and pituitary prolactin levels, whereas iproniazid and dopamine had little or no effect on prolactin levels. Ergocornine is believed to inhibit mammary tumor growth by depressing secretion of pituitary prolactin, but the mechanism(s) by which iproniazid inhibited mammary tumor growth is not clear.
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