Effects of a calcium/vitamin D/Zinc combination on anti-osteoporosis in ovariectomized rats

Osteoporosis is a major health problem in postmenopausal women, and characterized by deteriorated bone mass and micro-architecture. There have been some clinical trials demonstrating the beneficial effects of vitamin-D and some trace elements on calcium absorption and attenuation of osteoporosis development. However, effects of the combination of vitamin-D and zinc on calcium absorption and osteoporosis have not been adequately investigated.

Network pharmacology was first performed to explore possible correlations between calcium/vitamin D/zinc and osteoporosis. Forty-nine female Sprague-Dawley rats (6 months old, 250 ± 20 g) were randomized into 7 experimental groups with 7 animals per group for the in vivo study, including one sham surgery control group, one ovariectomizing (OVX) group, and 5 OVX plus treatment groups. At the end of animal experiment, animal tibia and femur leg bones and blood were collected for H&E staining, bone microstructure analysis by a micro-CT, measurement of bone and serum Ca, P and Zn concentrations, and immunohistochemical detection of macrophage-colony stimulating factor receptor (M-CSFR) and receptor activator of nuclear factor-kappa B ligand (RANKL).

The network pharmacology analysis identified 57 candidate targets that were related to the osteoporosis-Ca/VitD/Zn interconnections. Further pathway analysis suggested that the combined treatment of Ca, VitD and Zn attenuated osteoporosis via modulation of metabolic pathways. We found that a therapy with Ca/VitD-M/Zn-M (73 mg/kg/day Ca, 0.6 g/kg/day VitD3 and 0.6 mg/kg/day zinc citrate) could significantly suppress the progression of osteoporosis in rats. After the Ca/VitD-M/Zn-M treatment, the ratio of bone volume/tissue volume, trabecular number and the trabecular thickness were all significantly elevated while the extent of trabecular separation was significantly reduced. Additionally, both serum calcium and bone calcium levels were significantly upregulated by the Ca/VitD/Zn treatment in a dose-dependent manner. The combination of Ca/VitD-M/Zn-M was superiou to either Ca/VitD-L/Zn-L or Ca/VitD-H/Zn-H treatment for such an effect. Moreover, the osteoporosis-associated M-CSFR and RANKL factors were both significantly downregulated by the Ca/VitD-M/Zn-M treatment in bone tissues of OVX rats.

The combined supplement of VitD and Zn facilitates the Ca(2 +) absorption and attenuates the development of osteoporosis via down-regulation of osteoporosis-associated factors M-CSFR and RANKL, thus potentially constitutes an alternative therapy for the postmenopausal osteoporosis.