Saravanan Karuppagounder S, Sindhu Kizhakke M, Mohanakumar Kochupurackal P
Division of Clinical and Experimental Neuroscience, Indian Institute of Chemical Biology, 4, Raja S. C. Mullick Road, Calcutta 700 032, India.
Brain Res. 2005 Jul 12;1049(2):147-55. doi: 10.1016/j.brainres.2005.04.051.
We examined in Sprague-Dawley rats whether intranigral administration of complex-I inhibitor, rotenone, produces biochemical lesions in the striatum similar to those observed in Parkinson's disease (PD). Unilateral stereotaxic infusion of rotenone (2-12 mug in 1 mul) into substantia nigra (SN) pars compacta caused significant inhibition of complex-I activity and increased production of hydroxyl radicals in vivo as measured employing spectrophotometric and HPLC-electrochemical procedures, respectively. It also caused a significant time- and dose-dependent reduction of dopamine level, but not serotonin, in the ipsilateral striatum when assayed using an HPLC electrochemical method. This effect was found to be progressive for 90 days. A dose-dependent decrease in nigral glutathione level, as measured fluorimetrically, was also observed to be progressive till 90th day. A significant decrease in tyrosine hydroxylase immunoreactivity in the striatum (73 +/- 8.4% as assessed by densitometric studies) or in SN ipsilateral to the side of infusion suggested nigrostriatal neuronal degeneration. A dose of rotenone (6 microg in 1 microl) that caused 55% striatal dopamine depletion when infused into the SN failed to affect serotonin levels in the terminal regions when infused into the nucleus raphe dorsalis, indicating rotenone's specificity of action towards dopaminergic neurons. Our findings suggest that unilateral infusion of rotenone reproduces neurochemical and neuropathological features of hemiparkinsonism in rats and indicate an active involvement of oxidative stress in rotenone-induced nigrostriatal neurodegeneration. The present study also demonstrates more sensitivity of dopaminergic neurons towards rotenone and establishes mitochondrial complex-I damage as one of the major contributory components of neurodegeneration in PD. The progressive nature of pathology in this model closely mimics idiopathic PD, and absence of mortality warrants the use of this model in drug discovery programs.
我们在斯普拉格-道利大鼠中研究了向黑质内注射复合物I抑制剂鱼藤酮是否会在纹状体中产生类似于帕金森病（PD）中观察到的生化损伤。通过立体定位向黑质致密部单侧注入鱼藤酮（1微升中含2 - 12微克），分别采用分光光度法和高效液相色谱 - 电化学方法测定，结果显示其在体内显著抑制了复合物I的活性并增加了羟自由基的产生。当使用高效液相色谱电化学方法检测时，它还导致同侧纹状体中多巴胺水平出现显著的时间和剂量依赖性降低，但血清素水平未受影响。这种效应在90天内呈进行性发展。通过荧光法测定发现，黑质中谷胱甘肽水平的剂量依赖性降低在第90天前也呈进行性发展。纹状体中酪氨酸羟化酶免疫反应性显著降低（通过光密度研究评估为73±8.4%），或者在注入侧同侧的黑质中降低，提示黑质纹状体神经元变性。当向黑质注入一剂鱼藤酮（1微升中含6微克）导致纹状体多巴胺耗竭55%时，向背侧中缝核注入该剂量却未能影响终末区域的血清素水平，这表明鱼藤酮对多巴胺能神经元具有作用特异性。我们的研究结果表明，单侧注入鱼藤酮可重现大鼠偏侧帕金森病的神经化学和神经病理学特征，并表明氧化应激积极参与了鱼藤酮诱导的黑质纹状体神经变性。本研究还证明了多巴胺能神经元对鱼藤酮更敏感，并确定线粒体复合物I损伤是PD神经变性的主要促成因素之一。该模型中病理学的进行性特征与特发性PD非常相似，且无死亡率，这保证了该模型可用于药物发现项目。
