Effects of estrogen-depletion on rat casein gene expression.
Mammary tissue from rats that had been ovariectomized and adrenalectomized 4 weeks previously was compared to that from intact rats in terms of epithelial content and hormone-responsiveness in vitro. The endocrinectomy resulted in about a 30% enlargement of the gland, but led to a loss of only about 12% of the epithelium. This estrogen-depleted epithelium was able to acquire full responsiveness in vitro to insulin in terms of the accumulation of alpha-aminoisobutyric acid, and induction of glucose-6-phosphate and gluconate-6-phosphate dehydrogenases. It was also fully responsive to cortisol in relation to the induction of NADH-cytochrome C reductase, and to prolactin in terms of total RNA synthesis. However, estrogen-depletion led to an 82% loss in the ability of a unit amount of the epithelium to synthesize casein in response to these 3 hormones, and to a similar loss in relation to the accumulation of 25K casein mRNA. Estrogen administration in vivo could prevent and reverse the casein lesion. The disparity between constitutive and casein hormone-responsiveness in the absence of estrogen is discussed in relation to cell commitment.
D000315:Adrenalectomy; D000818:Animals; D002364:Caseins / Q000235:genetics*; D002369:Castration; D004247:DNA / Q000032:analysis; D004958:Estradiol / Q000494:pharmacology; D004967:Estrogens / Q000502:physiology*; D005260:Female; D005796:Genes / Q000187:drug effects; D006854:Hydrocortisone / Q000494:pharmacology; D008321:Mammary Glands, Animal / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009924:Organ Culture Techniques; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D011919:Rats, Inbred Strains; D014158:Transcription, Genetic / Q000187:drug effects
D002364:Caseins; D004967:Estrogens; D012333:RNA, Messenger; D004958:Estradiol; D004247:DNA; D006854:Hydrocortisone