Grant: Master's Award: Canada Graduate Scholarships

The role of vitamin D in regulating maternal bone metabolism During pregnancy, the fetus requires substantial calcium for normal development. The mother meets this need by increasing intestinal absorption of calcium. Breastfeeding (lactation) induces an even greater demand on the mother to provide calcium to the infant. To meet this need, the maternal skeleton resorbs to provide calcium to milk, resulting in 5-10% losses in bone mass in breastfeeding women (25-55% losses in lactating mice). After weaning, however, the maternal skeleton regains this lost mineral and becomes as strong or stronger than prior to pregnancy. Determining the factors that enable the mother's skeleton to regain bone mass so efficiently is important because the adult skeleton normally experiences only partial and slow recovery after other causes of bone loss. Prior work in our lab suggests that calcitriol, the active form of vitamin D, is not required to upregulate intestinal calcium absorption during pregnancy or to restore bone mass after lactation My project directly investigates the role of calcitriol in regulating bone metabolism during reproduction by studying mice that are unable to make calcitriol. My work will determine if the normal adaptations in bone metabolism during the reproductive cycles occur even when calcitriol is completely absent.