Nitric oxide induces osteoblast apoptosis through a mitochondria-dependent pathway.
Osteoblasts contribute to bone remodeling. Nitric oxide can regulate osteoblast activities. In this study, we attempted to evaluate the pathophysiological effects of nitric oxide on osteoblasts and its possible mechanism using neonatal rat calvarial osteoblasts as the experimental model. Exposure of osteoblasts to sodium nitroprusside, a nitric oxide donor, decreased alkaline phosphatase activities and cell viability in a concentration- and time-dependent manner. Apoptotic analysis revealed that sodium nitroprusside time-dependently increased the percentages of osteoblasts undergoing apoptosis. Administration of sodium nitroprusside reduced the mitochondrial membrane potential of osteoblasts. In parallel with the mitochondrial dysfunction, levels of intracellular reactive oxygen species and cytochrome c were significantly elevated following sodium nitroprusside administration. Exposure of osteoblasts to sodium nitroprusside significantly increased caspase-3 activity. Results of this study show that nitric oxide, decomposed from sodium nitroprusside, can induce osteoblast apoptosis through a mitochondrion-dependent cascade that causes mitochondrial dysfunction, release of intracellular reactive oxygen species and cytochrome c from mitochondria to cytoplasm, and activation of caspase-3.
Ho
Wei-Pin
WP
Department of Orthopedics, Wan-Fang Hospital, College of Medicine, Taipei Medical University, Taipei 110, Taiwan.
Chen
Ta-Liang
TL
Chiu
Wen-Ta
WT
Tai
Yu-Ting
YT
Chen
Ruei-Ming
RM
D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002478:Cells, Cultured; D045304:Cytochromes c / Q000096:biosynthesis; D008564:Membrane Potentials / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D051336:Mitochondrial Membranes / Q000187:drug effects / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D009599:Nitroprusside / Q000494:pharmacology; D010006:Osteoblasts / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000378:metabolism
D017382:Reactive Oxygen Species; D009599:Nitroprusside; D009569:Nitric Oxide; D045304:Cytochromes c; D000469:Alkaline Phosphatase; C505410:Casp3 protein, rat; D053148:Caspase 3; D020169:Caspases