Wang J-Y, Lee C-T, Wang J-Y
Graduate Institute of Medical Sciences and Department of Physiology, College of Medicine, Taipei Medical University, Taipei, Taiwan.
Department of Nursing, Hsin-Sheng College of Medical Care and Management, Taoyuan, Taiwan.
Neuroscience. 2014 Dec 5;281:164-77. doi: 10.1016/j.neuroscience.2014.09.048. Epub 2014 Oct 2.
Nitric oxide (NO) and oxidative stress caused by reactive oxygen species (ROS) accumulation are two important factors that lead to the progression of human neurological diseases. NO can be detrimental or protective to neurons under oxidative toxicity; however, in the case of brain exposure to oxidative stress, in addition to neurons, the existence of glia may also be disturbed by toxic ROS. The influence NO will have on ROS-mediated glial injury remains unclear. Here, we examined the effects of NO on cell viability under oxidative stress induced by hydrogen peroxide (H2O2) in rat primary mixed glia cultures, as well as pure astroglia and microglia cultures. We found that in mixed glia cultures, both H2O2 and NO donor S-nitroso-N-acetyl-d,l-penicillamine (SNAP) elicited cell death in a concentration-dependent manner. Combinations of H2O2 and SNAP at sublytic concentrations were sufficient to damage mixed glia, and sublytic concentrations of SNAP could reduce the insults that resulted from toxic H2O2. Furthermore, in microglia or astroglia, sublytic concentrations of H2O2 were toxic when combined with SNAP, and the potency was increased with an increased SNAP concentration. In microglia but not astroglia, a toxic H2O2-induced apoptotic injury was attenuated by a sublytic level of SNAP. H2O2 at toxic levels activated p38 mitogen-activated protein kinases (MAPK) and p53 pathways and increased DNA double strand breaks (DSBs) in microglia, whereas the rescue exerted by sublytic SNAP against toxic H2O2 occurred via the activation of both Akt and extracellular-signal-regulated kinase (ERK) cascades and decreased DNA DSBs. Moreover, a sublytic concentration of SNAP induced both heat shock protein 70 and heme oxygenase-1, which may be involved in decreasing the susceptibility of microglia to H2O2 toxicity. These results suggest that NO exhibits a concentration-dependent dual action of weakening or enhancing oxidative injury in mixed glia, particularly microglia.
一氧化氮（NO）和由活性氧（ROS）积累引起的氧化应激是导致人类神经疾病进展的两个重要因素。在氧化毒性下，NO对神经元可能有害或具有保护作用；然而，在大脑暴露于氧化应激的情况下，除了神经元外，神经胶质细胞的存在也可能受到有毒ROS的干扰。NO对ROS介导的神经胶质细胞损伤的影响尚不清楚。在此，我们研究了NO对大鼠原代混合神经胶质细胞培养物以及纯星形胶质细胞和小胶质细胞培养物中过氧化氢（H2O2）诱导的氧化应激下细胞活力的影响。我们发现，在混合神经胶质细胞培养物中，H2O2和NO供体S-亚硝基-N-乙酰-d，l-青霉胺（SNAP）均以浓度依赖性方式引发细胞死亡。亚裂解浓度的H2O2和SNAP组合足以损伤混合神经胶质细胞，亚裂解浓度的SNAP可减少有毒H2O2造成的损伤。此外，在小胶质细胞或星形胶质细胞中，亚裂解浓度的H2O2与SNAP联合时具有毒性，且毒性随SNAP浓度增加而增强。在小胶质细胞而非星形胶质细胞中，亚裂解水平的SNAP减轻了有毒H2O2诱导的凋亡损伤。有毒水平的H2O2激活了小胶质细胞中的p38丝裂原活化蛋白激酶（MAPK）和p53途径，并增加了DNA双链断裂（DSB），而亚裂解SNAP对有毒H2O2的挽救作用是通过激活Akt和细胞外信号调节激酶（ERK）级联反应并减少DNA DSB来实现的。此外，亚裂解浓度的SNAP诱导了热休克蛋白70和血红素加氧酶-1，这可能参与降低小胶质细胞对H2O2毒性的敏感性。这些结果表明，NO在混合神经胶质细胞，尤其是小胶质细胞中表现出浓度依赖性的双重作用，即减弱或增强氧化损伤。
