EFFECTS OF STRONTIUM ON CALCIUM-METABOLISM IN RATS .2. STRONTIUM PREVENTS THE INCREASED RATE OF BONE TURNOVER IN OVARIECTOMIZED RATS

The effects of stable strontium were investigated in ovariectomized (OVX) rats by calcium balance and calcium kinetic studies, histomorphometric analysis and measurements of calcium levels in bone. After 10 days of pair-feeding with a control diet, 71-day-old female Wistar rats were either sham-operated (Sham group) or ovariectomized. The OVX rats were divided into two subgroups: those that were treated with strontium (OVX+Sr group, strontium intake; 87.5 mu mol/day/rat) and those that were not (OVX group). Both groups were pair-fed their respective control or strontium diets for 2 weeks. Calcein and tetracycline were injected every 2 weeks from 1 week before ovariectomy to calculate the rate of bone formation in the diaphyseal femora cortex (% BFFC). In the OVX group, urinary calcium and % BFFC decreased, while bone resorption, bone formation and femora length increased at the end of the experiment, as compared with those in the Sham group. No such changes were observed in rats in the OVX + Sr group. The calcium balance, calcium levels in bone and trabecular bone volume in the metaphysis did not change in any of the three groups. These results suggest that strontium may be able to prevent the changes in bone turnover induced by estrogen deficiency.