Due to the great deal of effort that has gone into the study of osteoclastic differentiation and activation over the last few decades, the mechanisms of these two events have been discovered gradually. Nitric oxide(NO-), which is produced from arginine by a nitric oxide synthase, opened up a new area of biological research. Recently, it has been reported that NO- is produced by osteoblasts stimulated by lipopolysaccharide and several other cytokines. In this study, the effect of sodium nitroprusside(SNP), a donor of nitric oxide(NO-), on osteoclast-like cell formation and on mature osteoclast function was examined. To determine the mechanism of the inhibitory effects of SNP decreased not only the basal 45Ca release but also thee bone resorption induced by PTH and l,25-dihydroxyvitamin D3 (I ,25[OH]2D3). The inhibitory effect of SNP on bone resorption induced by PTH appeared 2 days after treatment, whereas SNP effect on inhibiting bone resorption induced by l,25[OH]2D3 appeared at the third days. When chicken and rat osteoclasts were cultured on dentin slices, treatment of 300µM SNP resulted in a significant decrease in dentin resorption by osteoclasts in terms of total resorption area and average individual area. We also examined the effect of SNP on formation of osteoclast-like cells that is TRAP-positive multinucleated cells from chicken and rat bone marrow cells in the presence or absence of 10-8M l,25[OH]2D3. The addition of 300 µM SNP inhibited the formation of TRAP-positive multinucleated cells. The present data suggest that SNP, possibly as a NO- donor, inhibits the osteoclastic differentiation and osteoclastic activity.
Due to the great deal of effort that has gone into the study of osteoclastic differentiation and activation over the last few decades, the mechanisms of these two events have been discovered gradually. Nitric oxide(NO-), which is produced from arginine by a nitric oxide synthase, opened up a new area of biological research. Recently, it has been reported that NO- is produced by osteoblasts stimulated by lipopolysaccharide and several other cytokines. In this study, the effect of sodium nitroprusside(SNP), a donor of nitric oxide(NO-), on osteoclast-like cell formation and on mature osteoclast function was examined. To determine the mechanism of the inhibitory effects of SNP decreased not only the basal 45Ca release but also thee bone resorption induced by PTH and l,25-dihydroxyvitamin D3 (I ,25[OH]2D3). The inhibitory effect of SNP on bone resorption induced by PTH appeared 2 days after treatment, whereas SNP effect on inhibiting bone resorption induced by l,25[OH]2D3 appeared at the third days. When chicken and rat osteoclasts were cultured on dentin slices, treatment of 300µM SNP resulted in a significant decrease in dentin resorption by osteoclasts in terms of total resorption area and average individual area. We also examined the effect of SNP on formation of osteoclast-like cells that is TRAP-positive multinucleated cells from chicken and rat bone marrow cells in the presence or absence of 10-8M l,25[OH]2D3. The addition of 300 µM SNP inhibited the formation of TRAP-positive multinucleated cells. The present data suggest that SNP, possibly as a NO- donor, inhibits the osteoclastic differentiation and osteoclastic activity.
