Abstract
The mechanism by which large doses of estrogen inhibit mammary tumor growth was studied. Whether estrogen-induced inhibition of growth of established mammary adenocarcinoma in rats could be overcome by giving prolactin was tested. 55-day-old Sprague-Dawley female rats were given a single iv injection of lipid emulsion containing 5 mg of 712-dimethylbenzanthracene. About 3 months later when most of the rats had mammary tumors the tumor-bearing rats were separated into 3 groups. Controls (Group 1) were injected once daily with .2 ml of corn oil. Group 2 was injected sc with 20 mcg of estradiol benzoate (EB) daily in .2 ml of corn oil. Group 3 was injected with 20 mcg of EB and 1 mg of ovine prolactin daily. The prolactin was injected sc in .2 ml of .9% saline. After 20 days of these treatments the control rats showed a gain in number of tumors and an increase in mean tumor diameter. Rats injected with 20 mcg of EB daily showed fewer tumors per rat and some reduction in average tumor diameter. Rats given both EB and prolactin showed a slight gain in average number of tumors per rat and a significant increase in mean total tumor diameters. Results show that injections of prolactin partially overcame the effects of estrogen.
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Schedule a callMore From: Proceedings of the Society for Experimental Biology and Medicine. Society for Experimental Biology and Medicine (New York, N.Y.)
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