Wang C, Sadovova N, Ali H K, Duhart H M, Fu X, Zou X, Patterson T A, Binienda Z K, Virmani A, Paule M G, Slikker W, Ali S F
Division of Neurotoxicology, HFT-132, National Center for Toxicological Research/U.S. Food and Drug Administration, Jefferson, AR 72079, USA.
Neuroscience. 2007 Jan 5;144(1):46-55. doi: 10.1016/j.neuroscience.2006.08.083. Epub 2006 Nov 2.
1-Methyl-4-phenylpyridinium ion (MPP+), an inhibitor of mitochondrial complex I, has been widely used as a neurotoxin because it elicits a severe Parkinson's disease-like syndrome with an elevation of intracellular reactive oxygen species (ROS) and apoptosis. L-carnitine plays an integral role in attenuating the brain injury associated with mitochondrial neurodegenerative disorders. The present study investigates the effects of L-carnitine against the toxicity of MPP+ in rat forebrain primary cultures. Cells in culture were treated for 24 h with 100, 250, 500 and 1000 microM MPP+ alone or co-incubated with L-carnitine. MPP+ produced a dose-related increase in DNA fragmentation as measured by cell death ELISA (enzyme-linked immunosorbent assay), an increase in the number of TUNEL (terminal dUTP nick-end labeling)-positive cells and a reduction in the mitochondrial metabolism of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). No significant effect was observed with the release of lactate dehydrogenase (LDH), indicating that cell death presumably occurred via apoptotic mechanisms. Co-incubation of MPP+ with L-carnitine significantly reduced MPP+-induced apoptosis. Western blot analyses showed that neurotoxic concentrations of MPP+ decreased the ratio of BCL-X(L) to Bax and decreased the protein levels of polysialic acid neural cell adhesion molecules (PSA-NCAM), a neuron specific marker. L-carnitine blocked these effects of MPP+ suggesting its potential therapeutic utility in degenerative disorders such as Parkinson's disease, Alzheimer's disease, ornithine transcarbamylase deficiency and other mitochondrial diseases.
1-甲基-4-苯基吡啶离子（MPP+）是线粒体复合物I的抑制剂，由于它会引发严重的帕金森病样综合征，导致细胞内活性氧（ROS）水平升高和细胞凋亡，因此已被广泛用作神经毒素。左旋肉碱在减轻与线粒体神经退行性疾病相关的脑损伤方面发挥着不可或缺的作用。本研究调查了左旋肉碱对大鼠前脑原代培养物中MPP+毒性的影响。培养的细胞分别用100、250、500和1000微摩尔的MPP+单独处理24小时，或与左旋肉碱共同孵育。通过细胞死亡ELISA（酶联免疫吸附测定）测量，MPP+导致DNA片段化呈剂量相关增加，TUNEL（末端脱氧核苷酸转移酶介导的dUTP缺口末端标记）阳性细胞数量增加，3-（4,5-二甲基噻唑-2-基）-2,5-二苯基四氮唑溴盐（MTT）的线粒体代谢减少。乳酸脱氢酶（LDH）释放未观察到显著影响，表明细胞死亡可能通过凋亡机制发生。MPP+与左旋肉碱共同孵育显著降低了MPP+诱导的细胞凋亡。蛋白质印迹分析表明，神经毒性浓度的MPP+降低了BCL-X(L)与Bax的比例，并降低了多唾液酸神经细胞粘附分子（PSA-NCAM，一种神经元特异性标志物）的蛋白质水平。左旋肉碱阻断了MPP+的这些作用，表明其在帕金森病、阿尔茨海默病、鸟氨酸转氨甲酰酶缺乏症和其他线粒体疾病等退行性疾病中具有潜在的治疗效用。
