Stimulation of Mammary Tumorigenesis and Suppression of Uterine Adenomyosis by Temporary Inhibition of Pituitary Prolactin Secretion during Youth in Mice 1

Abstract

Abstract

The effects of daily subcutaneous injections of 0.2 mg CB-154 (bromocriptine-mesilate), a potent suppressor of pituitary prolactin secretion, between 4 and 11 weeks of age on the occurrence of spontaneous mammary tumors and adenomyosis, a hyperplasia of endometrial tissue, were studied in the SHN strain of virgin mice. While there was little difference in mammary tumor incidence between experimental and control mice until 9 months of age, mammary tumor incidence in the experimental mice given CB-154 was significantly enhanced and surpassed that in the control after 10 months; 25 (53.2%), 31 (66.0%), and 36 (75.5%) of 47 experimental mice and 20 (27.5%), 23 (33.3%), and 34 (49.3%) of 69 control mice developed mammary tumors at 10, 11, and 12 months of age, respectively. In contrast, no adenomyosis appeared in 39 experimental mice at necropsy at 12 months of age, while 15 (46.9%) of 32 control mice developed it. Furthermore, five mice (15.6%) of the control had numerous subserosal nodules, an advanced state of adenomyosis. No significant correlation was observed in the control mice between the occurrence of mammary tumors and that of adenomyosis.