Endocrinology, Vol 115, 1078-1081, Copyright © 1984 by Endocrine Society

ARTICLES

Mammary fat pad may be a potential site for initiation of estrogen action in normal mouse mammary glands

G Shyamala and A Ferenczy

The effect of estradiol (E2) on mammary and uterine DNA synthesis has been examined in castrated virgin mice. In both these target tissues for E2, in vitro incorporation of thymidine into DNA begins 12 h after E2 treatment, and by 24 h there is approximately a 3-fold increase in the mammary glands and a 9-fold increase in the uterus. Whereas in the uterus by 48 h after E2 the rate of DNA synthesis has basically returned to control values, in the mammary gland a maximal stimulation of DNA synthesis is observed at this time, and even at 72 h after E2 there is still approximately a 2-fold increase in DNA synthesis. In vivo histoautoradiography reveals that, unlike in the uterus, 24 h after E2 there is virtually no uptake of labeled thymidine in the mammary epithelium; the increase in the uptake of thymidine is now mostly confined to the mammary adipose and connective tissues. However, 48 and 72 h after E2 there is extensive labeling of the mammary epithelium in addition to the adipose and connective tissues. These data lead us to suggest that both the mammary fat pad and epithelium are responsive to E2, and that, at least with respect to mammary cell proliferation, the mammary fat pad may be the site of initiation of estrogen action.

This article has been cited by other articles:

				M J Meyer, R P Rhoads, A V Capuco, E E Connor, A Hummel, Y R Boisclair, and M E Van Amburgh Ontogenic and nutritional regulation of steroid receptor and IGF-I transcript abundance in the prepubertal heifer mammary gland J. Endocrinol., October 1, 2007; 195(1): 59 - 66. [Abstract] [Full Text] [PDF]

				E. H. Wall, H. M. Crawford, S. E. Ellis, G. E. Dahl, and T. B. McFadden Mammary Response to Exogenous Prolactin or Frequent Milking During Early Lactation in Dairy Cows J Dairy Sci, December 1, 2006; 89(12): 4640 - 4648. [Abstract] [Full Text] [PDF]

				R. C. Humphreys, J. Lydon, B. W. O’Malley, and J. M. Rosen Mammary Gland Development Is Mediated by Both Stromal and Epithelial Progesterone Receptors Mol. Endocrinol., June 1, 1997; 11(6): 801 - 811. [Abstract] [Full Text]

				J P Lydon, F J DeMayo, C R Funk, S K Mani, A R Hughes, C A Montgomery, G Shyamala, O M Conneely, and B W O'Malley Mice lacking progesterone receptor exhibit pleiotropic reproductive abnormalities. Genes & Dev., September 15, 1995; 9(18): 2266 - 2278. [Abstract] [PDF]