Mammary Gland Development and α-Lactalbumin Production in Hypophysectomized, Pregnant Mice1
- 1 March 1989
- journal article
- research article
- Published by Oxford University Press (OUP) in Biology of Reproduction
- Vol. 40 (3) , 517-524
- https://doi.org/10.1095/biolreprod40.3.517
Abstract
Swiss Webster mice were hypophysectomized on Day 10 of pregnancy and the effect of the ablation on mammary gland development was estimated by measuring the total weight and the DNA, RNA, and .alpha.-lactalbumin contents and concentrations of the mammary gland on Day 14 and 18 of gestation. Although a significant increase in mammary gland weight occurred in the hypophysectomized animals between Days 10 and 18 of pregnancy, the mammary gland weight of the hypophysectomized mice was significantly reduced when compared with intact and sham-operated mice on both days 14 and 18 of pregnancy. The total RNA content of the mammary gland was also reduced in the hypophysectomized mice, although it increased significantly from Day 10 to Day 18. The .alpha.-lactalbumin content of the mammary gland increased only slightly between Days 10 and 14 of gestation in the intact and sham-operated mice, but a large increase was found on Day 18 in both groups. There was, on the other hand, no increment in the .alpha.-lactalbumin content of the mammary gland in the hypophysectomized mice either on Day 14 or 18 of gestation. The DNA content of the mammary gland was not affected by hypophysectomy when estimated on Days 14 and 18 of pregnancy. The effects of hypophysectomy on the concentrations of mouse placental lactogen II (mPL-II), progesterone, corticosterone, and thyroxine in the maternal serum were also assessed. The concentrations of mPL-II was significantly elevated in the hypophysectomized mice, whereas the circulating concentrations of both corticosterone and thyroxine were greatly reduced. The serum progesterone concentration was not significantly altered by hypophysectomy. It is concluded that hormones from the pituitary are not necessary for normal proliferation of mammary gland epithelial cells in the latter half of pregnancy in the mouse, probably because of the presence of mPL-II in high concentration during this period. On the other hand, normal protein synthesis, especially the synthesis of .alpha.-lactalbumin, was not maintained in the hypophysectomized mice despite the high concentration of mPL-II, presumably because of a lack of a synergistic effect of glucocorticoids and thyroid hormones and possibly growth hormone.This publication has 7 references indexed in Scilit:
- Purification and Partial Characterization of Two Prolactin-Like Glycoprotein Hormone Complexes from the Midpregnant Mouse Conceptus*Endocrinology, 1987
- Lactogenic response of cultured mouse mammary epithelial cells to mouse placental lactogenJournal of Endocrinology, 1986
- Immunohistochemical localization of follicle-stimulating hormone, luteinizing hormone, growth hormone, adrenocorticotrophic hormone and prolactin in the human placentaPlacenta, 1986
- Thyroid Hormones Enhance the Synthesis and Secretion ofα-Lactalbumin by Mouse Mammary Tissuein Vitro*Endocrinology, 1984
- Serum Placental Lactogen in Mice in Relation to Day of Gestation and Number of ConceptusesBiology of Reproduction, 1981
- Homologous radioimmunoassay for secreted mouse prolactinLife Sciences, 1981
- Lobulo-Alveolar Development of Mouse Mammary Glands Is Regulated by Thyroid HormonesEndocrinology, 1979