茶多酚对6-OHDA诱导的SH-SY5Y细胞凋亡的保护作用

茶多酚在体内具有广泛的生物活性和药理作用，有助于预防与氧化应激相关的疾病，比如癌症，心血管疾病，神经退行性疾病和衰老. 氧化应激参与了帕金森病（PD）的病理进程. 活性氧在PD的发病机制中发挥了重要的作用，氧自由基直接损伤细胞膜引起脂质过氧化，损伤蛋白质和各种功能酶引起蛋白质沉淀，诱导促凋亡因子的表达，损伤DNA，最终导致了细胞的凋亡. 然而，关于茶多酚对PD的预防和治疗作用目前还不清楚. 本文应用氧化应激诱导的PD病理细胞模型，评价了茶多酚的神经保护作用. 结果表明茶多酚这类植物天然抗氧化剂对氧化应激诱导的细胞凋亡具有明确的抑制作用. 实验中我们选择了6-OHDA诱导的SH-SY5Y细胞作为细胞模型, 运用了MTT、流式细胞术、荧光显微成相, 竞争性ELISA和蛋白质杂交等方法研究了SH-SY5Y细胞的凋亡特性. 结果表明，6-OHDA对SH-SY5Y有时间-浓度依赖性细胞毒性，100 μmol/L 6-OHDA处理24 h，细胞活力减少50 %，同时伴随着活性氧增加（用ＥＳR），线粒体膜电位降低，细胞内钙离子和一氧化氮增加，nNOS和iNOS表达量上升及蛋白结合的硝基酪氨酸水平升高. 单独茶多酚处理对细胞没有太大的影响，而茶多酚预处理可显著降低6-OHDA所产生的细胞毒性. 溶液实验证明，茶多酚对6-OHDA的自氧化有浓度-时间依赖性抑制作用（用ＥＳＲ）. 本研究表明茶多酚可能是通过活性氧-一氧化氮途径，减少过氧亚硝基的生成来对6-OHDA诱导的细胞凋亡表现保护作用的. 本文的实验结果提示茶多酚在治疗PD等慢性神经退行性疾病上可能是一种有着潜在疗效的药物.

Protective Effect of Green Tea Polyphenols against 6-OHDA Induced Apoptosis in SH-SY5Y Cells through ROS-NO Pathway

Green tea polyphenols(GTP) are thought to be effective in preventing oxidative stress-related diseases,including cancer,cardiovascular disease,neurodegenerative disease and aging.In this study,the protective mechanisms of GTP against pro-parkinsonian neurotoxin 6-hydroxydopamine(6-OHDA) induced apoptosis in SH-SY5Y cells were investigated.The results show that GTP treatment rescued the changes in condensed nuclear and apoptotic bodies,attenuated 6-OHDA-induced early apoptosis,prevented the decrease in mitochondrial membrane potential,and suppressed accumulation of reactive oxygen species(ROS)(measured with ESR) and of intracellular free Ca~(2 ).It was found that GTP treatment also counteracted 6-OHDA-induced nitric oxide increase and overexpression of nNOS and iNOS,and decreased the level of protein-bound 3-nitrotyrosine(3-NT).In addition,GTP treatment inhibited the auto-oxidation of 6-OHDA and scavenged oxygen free radicals in a dose-and time-dependent manner.Our results show that the protective effects of GTP against 6-OHDA Induced apoptosis in SH-SY5Y cells are mediated,at least in part,by controlling the ROS-NO pathway.