Abstract: Objective　To clarify the promotion effect of mouse osteoclast differentiation and osteoporosis by high-salt dietary.　Methods　Bone marrow mononuclear cells of C57 mice were obtained and induced to differentiate into osteoclasts. During this procedure, cells were cultured in each of 3 kinds of medium: no salt addition (control group), addition of 20 mmol/L salt (low-dose group), and addition of 40 mmol/L salt (high-dose group). The quantity of formed osteoclasts was acquired and compared among all 3 groups. In in-vivo study, a total of 24 C57 mice were divided into 3 groups randomly and equally: a normal group (regular feeding), an ovariectomy group (removal of ovary and regular feeding), and a high-salt group (removal of ovary, fed with 8% salt and drinking normal saline). At 6 weeks after administration, in all 3 cohorts, the number of generated osteoclasts in left femurs, as well as indicators associated with bone resorption and protection in serum were acquired. Moreover, bone histomorphometric parameters in right femurs were obtained and compared between each group using micro-CT.　Results　High-salt medium ex vitro enhanced the formation of osteoclasts significantly. Similarly, in vivo study found the largest number of osteoclasts in the high-salt group in comparison with the other 2 cohorts. Also in this group, C-telopeptide of type I collagen and receptor activator of nuclear factor-κ B ligand increased at different levels, while osteoprotegerin decreased remarkably. With respect to bone histomorphometric parameters in the high-salt group,  bone volume/total volume, cortical wall thickness, trabecular number and trabecular thickness were significantly increased whereas bone surface area/ bone volume, trabecular spacing and trabecular pattern factor were increased at various levels.　Conclusions　High-salt dietary enables the occurrence of osteoporosis through activating differentiation of bone marrow mononuclear cells into osteoclasts and strengthening of overall bone-resorption potential.

Key words: High-salt dietary, 　Osteoclast, 　Bone-resorption, 　Osteoporosis