AJP - Endocrinology and Metabolism, Vol 263, Issue 6 E1077-E1085, Copyright © 1992 by American Physiological Society
Production of parathyroid hormone-related protein by the rat mammary gland in pregnancy and lactation
M. Rakopoulos, S. J. Vargas, M. T. Gillespie, P. W. Ho, H. Diefenbach-Jagger, D. D. Leaver, V. Grill, J. M. Moseley, J. A. Danks and T. J. Martin
St. Vincent's Institute of Medical Research, Fitzroy, Victoria, Australia.
Production of parathyroid hormone-related protein by the rat mammary gland
in pregnancy and lactation. Am. J. Physiol. 263 (Endocrinol. Metab. 26):
E1077-E1085, 1992.--Production of parathyroid hormone-related protein
(PTHrP) by the mammary gland of Sprague-Dawley rats has been examined using
immunohistochemistry and in situ hybridization to detect PTHrP and PTHrP
mRNA, respectively. PTHrP and PTHrP mRNA could be demonstrated in nests of
epithelial cells of the developing mammary gland at day 14 of pregnancy and
in the epithelial secretory cells lining the alveoli during the latter
stages of pregnancy and during lactation. A specific radioimmunoassay was
also used to measure the concentration of PTHrP secreted in the milk
throughout lactation. The concentration of PTHrP in milk was relatively low
initially but increased during the latter stages of lactation, whereas
calcium concentrations remained virtually constant throughout lactation. No
correlation was found between the concentrations of calcium and PTHrP in
rat milk. These results show that PTHrP is present in rat milk and also in
mammary tissue before parturition, and therefore it may assist in the
development of the mammary gland during pregnancy.
