Xu Z, Cawthon D, McCastlain K A, Slikker W, Ali S F
Neurochemistry Laboratory, Division of Neurotoxicology, National Center for Toxicological Research, Food and Drug Administration, Jefferson, Arkansas 72079, USA.
Synapse. 2005 Jan;55(1):45-51. doi: 10.1002/syn.20089.
1-methyl-4-phenyl-1,2,4,6,-tetrahydropyridine (MPTP) is a selective neurotoxin that produces striatal dopamine depletion resulting in parkinsonism like symptoms in humans and is, therefore, used to generate animal models for Parkinson's disease (PD). In this study, C57BL/6N mice were treated with MPTP acutely (3x20 mg/kg, 2-hour interval, one day injection). Mice were then sacrificed 24 hours after the last injection and brain tissue was collected for analysis. Significant decrease of striatal dopamine (DA) and the metabolites (DOPAC, HVA) was observed after MPTP treatment. MPTP also reduced protein expression of tyrosine hydroxylase (TH) in the striatum. Real time RT-PCR was used to examine selective genes of the dopaminergic system in the substantia nigra. Our data demonstrated that MPTP significantly decreased gene expression of TH, dopamine transporter (DAT), and vesicle monoamine transporter (VMAT), coinciding with the pattern of dopamine concentration changes and protein expression after MPTP treatment. Although a significant decrease of DA metabolites was observed in striatum, there was no change in the expression of monoamine oxidases (MAO-A, MAO-B) or catechol O-methyltransferase (COMT), indicating that these changes might be simply a consequence of reduced monoamine levels. In addition, gene expression of alpha-synuclein was also decreased with MPTP treatment, but there was no change in beta-synuclein and parkin. This is the first study using real-time PCR to indicate that MPTP selectively alters gene expression and provides information for clinical studies in PD. Future studies will focus on gene expression of other pathways that may be affected by MPTP treatment and investigation of gene expression in specific cell types in vivo using LCM technology.
1-甲基-4-苯基-1,2,4,6-四氢吡啶（MPTP）是一种选择性神经毒素，可导致纹状体多巴胺耗竭，从而在人类中产生类似帕金森病的症状，因此被用于建立帕金森病（PD）的动物模型。在本研究中，对C57BL/6N小鼠进行急性MPTP处理（3×20mg/kg，间隔2小时，注射一天）。然后在最后一次注射后24小时处死小鼠，并收集脑组织进行分析。MPTP处理后，观察到纹状体多巴胺（DA）及其代谢产物（DOPAC、HVA）显著减少。MPTP还降低了纹状体中酪氨酸羟化酶（TH）的蛋白表达。采用实时RT-PCR检测黑质中多巴胺能系统的选择性基因。我们的数据表明，MPTP显著降低了TH、多巴胺转运体（DAT）和囊泡单胺转运体（VMAT）的基因表达，这与MPTP处理后多巴胺浓度变化和蛋白表达模式一致。尽管在纹状体中观察到DA代谢产物显著减少，但单胺氧化酶（MAO-A、MAO-B）或儿茶酚-O-甲基转移酶（COMT）的表达没有变化，这表明这些变化可能仅仅是单胺水平降低的结果。此外，MPTP处理后α-突触核蛋白的基因表达也降低，但β-突触核蛋白和帕金森蛋白没有变化。这是第一项使用实时PCR表明MPTP选择性改变基因表达并为PD临床研究提供信息的研究。未来的研究将集中于MPTP处理可能影响的其他途径的基因表达，以及使用激光捕获显微切割技术在体内特定细胞类型中研究基因表达。
