title: Prophylaxis of spontaneous mammary tumorigenesis by temporal inhibition of prolactin secretion in rats at young ages.
abstract: The effects of temporal prolactin suppression during the limited periods of early age on spontaneous mammary tumorigenesis at advanced ages were examined in rats. Daily s.c. injections of 0.5 mg 2-bromo-alpha-ergocryptine mesylate, a potent suppressor of pituitary prolactin secretion, into virgin rats for 7 weeks beginning at 4 weeks of age resulted in almost complete prevention of mammary tumor appearance by 20 months of age. The incidence of tumors in this group (Group 1) was 3.3% (1 of 30), significantly smaller than that of the control [Group 2, 47.6% (10 of 21)]. Treatment given between 11 and 18 weeks of age inhibited mammary tumor incidence to a lesser extent [Group 3, 20% (6 of 30)], although tumor incidence was still significantly smaller than that in the corresponding control [Group 4, 41.2% (7 of 17)]. Serum prolactin level was decreased significantly by 2-bromo-alpha-ergocryptine mesylate; the levels on the evening of proestrus in the last week of injection were 18 +/- 3 (S.E.), 326 +/- 37, 15 +/- 2, and 460 +/- 55 ng/ml in Groups 1, 2, 3, and 4, respectively. Body weight change and pattern of estrous cycles were not affected by the treatment.
mesh_terms: D000367:Age Factors; D000818:Animals; D001971:Bromocriptine / Q000494:pharmacology*; D005260:Female; D008325:Mammary Neoplasms, Experimental / Q000453:epidemiology / Q000473:pathology / Q000517:prevention & control*; D011388:Prolactin / Q000378:metabolism*; D051381:Rats
chemical_list: D001971:Bromocriptine; D011388:Prolactin