损毁丘脑底核阻止6-OHDA对大鼠多巴胺能神经元的损伤作用

Prevention of neurotoxin damage of 6－OHDA to dopaminergic nigral neuron by subthalamic nucleus lesions

目的 观察不同时期毁损丘脑底核对大鼠中脑黑质多巴胺神经元6－羟基多巴胺（6－OHDA）损伤的保护作用。方法 将60只Wistar大鼠随机分为6组，每组10只。对照组采用6－OHDA立体定向注入大鼠右侧前脑内侧束（MFB）和中脑被盖腹侧区（VTA），制成偏侧帕金森病（PD）模型。实验组分为第Ⅰ、Ⅱ、Ⅲ、Ⅳ和Ⅴ组，分别于6－OHDA注射前7d、注射后1h、2h、3d、7d 5个不同时间点，局部注射海藻氨酸（KA）破坏STN。4周后处死大鼠，采用免疫组化染色方法，定量测量各组大鼠黑质致密区（SNc）区TH免疫阳性反应神经元数目。实验数据采用方差分析和t检验统计学处理。结果 第Ⅰ、Ⅱ、Ⅲ、Ⅳ、Ⅴ实验组以及对照组的注射侧TH神经元存活数目分别为71．46±6．84、57．07±5．54、51．09±4．85、12．68±2．67、4．15±1．60和3．40±1．54个每张切片，为对侧的96．7％、72．9％、69．8％、17．2％、5．6％及4．4％。各实验组注射侧TH神经元均比对照组同侧数目多（P ＜ 0．05），但Ⅴ组无显著性差异（P ＞0．05）。各实验组之间比较，均有明显差异，其中以Ⅰ组TH神经元存活的数量最多（P ＜0．01）。结论 早期毁损丘脑底核（STN）可减轻6－OHDA对黑质致密部多巴胺（DA）能神经元的损伤和细胞数量的缺失；

Objective To investigate whether lesioning STN could prevent the toxicity of the selective dopaminergic neurotoxin 6－hydroxydopamine （6－OHDA）． Methods A total of 60 adult male Wistar rats were divided in to 6 groups （each of the 6 groups consisting of 10 rats）． Control group received a unilateral microinjection of 6－hydroxydopamine into the right ventral tegmental area （VTA） and the right median forebrain bundle （MFP）． Group Ⅰ received an administration of kainic acid （KA） into the right subthalamic nucleus and 1－week later an injection of 6－OHDA in the right VTA and MFP． Group Ⅱ, Ⅲ、Ⅳ、Ⅴ received an injection of 6－OHDA in the right VTA and MFP, 1h, 2h, 3d, and 7d before KA in the right STN respectively． Four weeks later, the changes of tyrosine hydroxylase－like （dopaminergic） neurons in the SNc were investigated with immunocytochemical and morphometrical methods． Data were reported as mean±SD． Statistical significance levels were analysed using a one－way ANOVA and paired－samples T－test． Results The number of tyrosine hydroxylase－immunoreactive cells in the SNc on the injected side of treated groups （group Ⅰ、Ⅱ、Ⅲ、Ⅳ and Ⅴ） and control group were 71．46±6．84, 57．07±5．54, 51．09±4．85, 12．68±2．67, 4．15±1．60 and 3．40±1．54slice, which decreased to the level of 96．7％, 72．9％, 69．8％, 17．2％, 5．6％ and 4．4％ of the non－injected side respectively． The number of TH positive in Group Ⅰ、Ⅱ、Ⅲ and Ⅳ significantly increase in comparison with the controls （P ＜0．05）． In group Ⅴ, there were no remarkable difference in contrast to the number of TH positive neurons of the controls （P ＞0．05）． The difference of the number of TH positive between group Ⅰ、Ⅱ、Ⅲ、Ⅳ and Ⅴwere statistically significant（P ＜0．01）．Conclusion The results indicated that early STN ablation could provide antiglutamate－based neuroprotection of the dopaminergic nigrostriatal pathway against 6－OHDA toxicity and open a new way for slowing or halting the progression of neurodegeneration in Parkinson＇s disease．