Prophylaxis of spontaneous mammary tumorigenesis by temporal inhibition of prolactin secretion in rats at young ages.
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.
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
D001971:Bromocriptine; D011388:Prolactin