The purpose of this study was to evaluate the efficacy of
zinc (Zn)-containing
beta-tricalcium phosphate (Zn-TCP) in correcting the bone
mineral deficiency noted in
osteoporosis using ovariectomized rat model. Four rats were used for each of the four experimental groups: D0, D10, D20, and N10. The rats in D0, D10, and D20 groups were ovariectomized, and fed a
vitamin D-, Ca-, and Zn-deficient diet, and induced Zn-deficient
osteoporoses for 9 weeks. In contrast, the N10 group was the normal rats fed normal healthy diet for 9 weeks. D0 group was injected with pure
beta-TCP suspension, D10 and D20 groups were injected with
suspensions containing 10 mg of 10 mol % (6.17 wt % Zn) and 20 mol % (12.05 wt % Zn) Zn-TCP, respectively, and the healthy group, N10 were injected with 10 mol %. Zn-TCP
suspensions.
Injections were administered intramuscularly in the left thigh once a week in all rats, and fed a
vitamin D- and Zn-deficient diet for 9 weeks. The plasma
calcium (Ca) and Zn levels, plasma
alkaline phosphatase activity (ALP) and bone mineral density (BMD) of the lumbar vertebra and femora were measured. The plasma Zn levels in all the rats were between 1.1 and 2.8 microg/mL. The areas under the curves for the Ca, Zn, and ALP (Ca-AUC, Zn-AUC, and ALP-AUC) levels between 0 and 63 days were calculated. Results for the AUCs were as follows: (1) the Zn-AUCs were in the order of N10 = D20 > D10 > D0; (2) the Ca-AUCs for D0, D10 groups were significantly lower than that for the N10 group; (3) the ALP-AUCs for the D10 and D20 groups were significantly higher than that for the N10 group, and that of the D0 group was in between those. The
body weight of D10 and D20 groups significantly increased with time, that of the D0 group increased slightly, and that of the N10 group remained unchanged for the entire experimental period. The BMD of the lumbar vertebrae of the D10 and D20 groups (about 100 mg/cm(2)) was significantly higher than that of the D0 group but lower than that of the N10 group. The BMD of the left femur increased more than that of the right femur with the increase in the amount of Zn in the
suspension. The results of this study suggest that the local effect on BMD was more pronounced than the effect on the whole body.