PROPHYLAXIS OF SPONTANEOUS MAMMARY TUMORIGENESIS BY TEMPORAL INHIBITION OF PROLACTIN SECRETION IN RATS AT YOUNG AGES

  • 1 January 1981
    • journal article
    • research article
    • Vol. 41  (5) , 1935-1937
Abstract
The effects of temporal prolactin [PRL] 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 PRL secretion, into virgin rats for 7 wk beginning at 4 wk of age resulted in almost complete prevention of mammary tumor appearance by 20 mo. 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 11-18 wk 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 PRL 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.