Grant: Operating Grant

During pregnancy and breast-feeding (lactation), women lose calcium from their bodies in order to provide it to their babies. During pregnancy, women meet this demand for calcium by doubling the rate of absorption of calcium by the intestines and breaking down a small amount of bone. During six months of lactation, women provide calcium largely by losing 5 to 10% of the amount of bone in the skeleton (teen moms may lose up to 15%). The rate of bone loss during lactation is extremely fast when it is considered that losses of more than 1% per year are termed "rapid" in women after menopause. After weaning the baby, bone that was lost is completely restored at rates that far exceed what current treatments for osteoporosis can accomplish. This recovery is especially remarkable when it is considered that the skeleton normally has partial and slow recovery after other causes of bone loss. In this work we are trying to understand how the skeleton restores itself so quickly and readily after lactation, because this knowledge might lead to new ways to build bone in people with osteoporosis or other skeletal problems. This work involves mice, which lose up to 55% of bone mass during 3 weeks of lactation, but fully restore the skeleton within 10-14 days after weaning.