AJP - Endocrinology and Metabolism, Vol 259, Issue 6 E792-E796, Copyright © 1990 by American Physiological Society
Parathyroid hormone-related protein and calcium homeostasis in lactating mice
M. E. Melton, J. J. D'Anza, S. A. Wimbiscus, V. Grill, T. J. Martin and S. C. Kukreja
Departmen of Medicine, Department of Veterans Affairs West Side, Chicago, Illinois.
Parathyroid hormone (PTH)-related protein has been shown to be a factor
responsible for hypercalcemia of malignancy. Recent studies have shown the
presence of mRNA for PTH-related protein in lactating breast tissue,
suggesting a physiological role for this peptide during lactation. In the
present study, we evaluated the effect of neutralization of PTH-related
protein activity in lactating mice (by passive immunization) on various
parameters of maternal and neonatal calcium homeostasis. PTH-related
protein bioactivity, as tested in the adenylate cyclase assay, was present
in mouse milk, and this activity was completely neutralized by the antisera
used in the present study. In lactating mice, the effects of injection of
PTH-related protein antisera on maternal serum calcium concentrations, milk
calcium and phosphorus concentration, pup growth, dam femur calcium
content, and pup calcium content were similar to those of the injection of
normal rabbit serum. Therefore, maternal PTH-related protein does not
appear to have a role in calcium homeostasis during lactation.
