Nakai Masami, Mori Atsushi, Watanabe Akihito, Mitsumoto Yasuhide
Research Unit for Neurological Diseases, Second Institute of New Drug Discovery, Otsuka Pharmaceutical Co., Ltd. Tokushima 771-0192, Japan.
Exp Neurol. 2003 Jan;179(1):103-10. doi: 10.1006/exnr.2002.8056.
Mitochondrial dysfunction has long been implicated in the death of nigrostriatal dopaminergic neurons in Parkinson's disease (PD) and its experimental models. Here we further analyzed changes in the mitochondrial oxidation-reduction (REDOX) activity and membrane potential (Deltapsi(m)) of striatal synaptosomes after the infusion of 1-methyl-4-phenylpyridinium (MPP+) into rat striatum. MPP+ (40 nmol) treatment produced decreases in mitochondrial REDOX activity and Deltapsi(m) at 18 h, as measured by fluorometric analysis with both Alamar blue and JC-1 (5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolyl-carbocyanine iodide) dyes. At this time point, tyrosine hydroxylase (TH) and dopamine transporter (DAT) protein levels were not altered, but both decreased at 7 days after MPP+ (40 nmol) infusion. Both measures of mitochondrial dysfunction induced by MPP+ (40 nmol) at 18 h were attenuated, at least in part, by pretreatment with a selective dopamine uptake inhibitor GBR-12909 (1-(2-(bis(4-fluorophenyl)methoxy)ethyl)-4-(3-phenylpropyl) piperazine). In addition, GBR-12909 partially attenuated MPP+ (40 nmol)-caused a loss of striatal nerve terminal as indicated by decreases in TH and DAT immunoreactivities as well as dopamine and its metabolites levels. The present study indicates that decreases in mitochondrial REDOX activity and Deltapsi(m) may play a role in MPP+ -induced dopaminergic neurotoxicity, and further provides that improvement of mitochondrial dysfunction may be a better way to slow progressive dopaminergic neurodegeneration commonly associated with PD.
线粒体功能障碍长期以来一直被认为与帕金森病（PD）及其实验模型中黑质纹状体多巴胺能神经元的死亡有关。在此，我们进一步分析了向大鼠纹状体注射1-甲基-4-苯基吡啶离子（MPP+）后，纹状体突触体中线粒体氧化还原（REDOX）活性和膜电位（Δψm）的变化。通过使用阿拉玛蓝和JC-1（5,5',6,6'-四氯-1,1',3,3'-四乙基苯并咪唑基碳氰碘化物）染料进行荧光分析测定，MPP+（40 nmol）处理在18小时时导致线粒体REDOX活性和Δψm降低。在这个时间点，酪氨酸羟化酶（TH）和多巴胺转运体（DAT）蛋白水平没有改变，但在MPP+（40 nmol）注射后7天两者均降低。MPP+（40 nmol）在18小时时诱导的线粒体功能障碍的两种测量指标至少部分地被选择性多巴胺摄取抑制剂GBR-12909（1-(2-(双(4-氟苯基)甲氧基)乙基)-4-(3-苯基丙基)哌嗪）预处理所减弱。此外，GBR-12909部分减弱了MPP+（40 nmol）导致的纹状体神经末梢损失，这表现为TH和DAT免疫反应性以及多巴胺及其代谢物水平的降低。本研究表明，线粒体REDOX活性和Δψm的降低可能在MPP+诱导的多巴胺能神经毒性中起作用，并进一步表明改善线粒体功能障碍可能是减缓通常与PD相关的进行性多巴胺能神经退行性变的更好方法。
