Effects of nitric oxide and nitric oxide synthase inhibitors on mitochondrial function of nucleus pulposus cells / 中国组织工程研究

ABSTRACT

BACKGROUND:Nitric oxide can interfere with the function of mitochondria, and accelerate the intervertebral disc damage and degeneration by interfering with the release of inflammatory cytokines. Nitric oxide is an important inflammatory cel medium leading to degeneration of intervertebral disc induced by pressure and other external factors. OBJECTIVE:To investigate the regulatory effect of nitric oxide and nitric oxide synthase inhibitor niacinamide on mitochondrial function and its association with biological behavior of rabbit nucleus pulposus. METHODS:Cultured nucleus pulposus cel s of rabbit lumbar intervertebral disc were randomly divided into six groupsnormal blank control group, 10μmol/L sodium nitroprusside group, 100μmol/L sodium nitroprusside group, 200μmol/L sodium nitroprusside group, 0.05 g/L nicotinamide group (100μmol/L sodium nitroprusside+0.05g/L nicotinamide), and 0.5 g/L nicotinamide group (100μmol/L sodium nitroprusside and 0.5 g/L nicotinamide). Different doses of nitric oxide donor sodium nitroprusside and nicotinamide were added in the medium of each group. Three days after intervention, cel proliferation activity, intracel ular ATP concentration, cel nitric oxide synthase activity, cel ular reactive oxygen species level, and mitochondrial membrane potential were detected respectively. RESULTS AND CONCLUSION:(1) After 3 days of rabbit nucleus pulposus cel s intervened by different concentrations of sodium nitroprusside, intracel ular nitric oxide synthase content increased with sodium nitroprusside volume increase, and ATP concentration decreased along with sodium nitroprusside volume increase;there were significantly differences between the normal control group and sodium nitroprusside groups (P<0.01). (2) Reactive oxygen species could be increased in the sodium nitroprusside group. Niacinamide groups indicated a dose-dependent manner to improve the increase of cel ular reactive oxygen species levels with sodium nitroprusside intervention (P<0.01). (3) In the sodium nitroprusside groups, nucleus pulposus cel membrane potential decreased. In the niacinamide groups, sodium nitroprusside-induced decline in mitochondrial membrane potential was reduced (P<0.01). (4) Niacinamide groups also indicated a dose-dependent manner to improve the proliferative activity of nucleus pulposus cel s as compared with sodium nitroprusside groups (P<0.01). Significant differences were determined between the two groups (P<0.01). (5) Results suggest that the excess nitric oxide can damage mitochondrial metabolic function of rabbit nucleus pulposus cel s and cause cel energy metabolism. Niacinamide can reverse these damages by inhibiting nitric oxide synthesis, thereby contributing to the prevention against intervertebral disc degeneration.