17beta-oestradiol and Enovid mammary tumorigenesis in C3H/HeJ female mice: counteraction by concurrent 2-bromo-alpha-ergocryptine.
Chronic administration of 17beta-oestradiol (via drinking water) or the oral contraceptive Enovid (norethynodrel and mestranol) (0-1 mg injected s.c. twice weekly) to nulliparous C3H/HeJ female mice, beginning at one month of age and terminating at 20 months (17beta-oestradiol) or 22 months (Enovid), significantly increased the incidence of mammary tumours over solvent-treated controls. Concurrent treatment of the steroid-treated mice with 2-bromo-alpha-ergocryptine (CB-154) (0-1 mg s.c. injected daily) significantly reduced mammary tumour incidence and mammary hyperplastic nodule development to the control level. CB-154 is an efficacious inhibitor of pituitary prolactin secretion. These results demonstrate that steroid-induced mammary gland dysplasias can be sharply reduced by chronic CB-154 treatment, and suggest that some of the mammary tumorigenic activities of oestrogenic steroids in C3H mice are mediated via an increased secretion of pituitary prolactin.
D000818:Animals; D001971:Bromocriptine / Q000494:pharmacology*; D003276:Contraceptives, Oral / Q000633:toxicity*; D003277:Contraceptives, Oral, Combined / Q000037:antagonists & inhibitors / Q000633:toxicity*; D004873:Ergolines / Q000494:pharmacology*; D004958:Estradiol / Q000633:toxicity*; D004965:Estrogen Antagonists; D005260:Female; D008325:Mammary Neoplasms, Experimental / Q000139:chemically induced* / Q000517:prevention & control; D008656:Mestranol / Q000633:toxicity; D051379:Mice; D009641:Norethynodrel / Q000633:toxicity
D003276:Contraceptives, Oral; D003277:Contraceptives, Oral, Combined; D004873:Ergolines; D004965:Estrogen Antagonists; D001971:Bromocriptine; D004958:Estradiol; D009641:Norethynodrel; D008656:Mestranol