Department of Anatomy, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China.
Institute of Medicine, College of Medicine, Jishou University, Jishou, China.
Neurochem Res. 2019 May;44(5):1079-1089. doi: 10.1007/s11064-019-02739-y. Epub 2019 Feb 4.
Dopaminergic neuron degeneration is known to give rise to dendrite injury and spine loss of striatal neurons, however, changes of intrastriatal glutamatergic terminals and their synapses after 6-hydroxydopamine (6OHDA)-induced dopamine (DA)-depletion remains controversial. To confirm the effect of striatal DA-depletion on the morphology and protein levels of corticostriatal and thalamostriatal glutamatergic terminals and synapses, immunohistochemistry, immuno-electron microscope (EM), western blotting techniques were performed on Parkinson's disease rat models in this study. The experimental results of this study showed that: (1) 6OHDA-induced DA-depletion resulted in a remarkable increase of Vesicular glutamate transporter 1 (VGlut1) + and Vesicular glutamate transporter 2 (VGlut2)+ terminal densities at both the light microscope (LM) and EM levels, and VGlut1+ and VGlut2+ terminal sizes were shown to be enlarged by immuno-EM; (2) Striatal DA-depletion resulted in a decrease in both the total and axospinous terminal fractions of VGlut1+ terminals, but the axodendritic terminal fraction was not significantly different from the control group. However, total, axospinous and axodendritic terminal fractions for VGlut2+ terminals declined significantly after striatal DA-depletion. (3) Western blotting data showed that striatal DA-depletion up-regulated the expression levels of the VGlut1 and VGlut2 proteins. These results suggest that 6OHDA-induced DA-depletion affects corticostriatal and thalamostriatal glutamatergic synaptic inputs, which are involved in the pathological process of striatal neuron injury induced by DA-depletion.
多巴胺能神经元退化已知会导致纹状体神经元的树突损伤和棘突丢失，然而，6-羟多巴胺（6OHDA）诱导的多巴胺（DA）耗竭后纹状体谷氨酸能末梢及其突触的变化仍存在争议。为了确认纹状体 DA 耗竭对皮质纹状体和丘脑纹状体谷氨酸能末梢和突触的形态和蛋白水平的影响，本研究在帕金森病大鼠模型中进行了免疫组织化学、免疫电镜（EM）和 Western 印迹技术。本研究的实验结果表明：（1）6OHDA 诱导的 DA 耗竭导致 VGlut1+和 VGlut2+末梢密度在光镜（LM）和 EM 水平上显著增加，并且 VGlut1+和 VGlut2+末梢大小通过免疫 EM 显示增大；（2）纹状体 DA 耗竭导致 VGlut1+末梢的总和棘突末梢分数减少，但轴树突末梢分数与对照组无显著差异。然而，VGlut2+末梢的总、棘突和轴树突末梢分数在纹状体 DA 耗竭后显著下降。（3）Western 印迹数据显示纹状体 DA 耗竭上调了 VGlut1 和 VGlut2 蛋白的表达水平。这些结果表明，6OHDA 诱导的 DA 耗竭影响皮质纹状体和丘脑纹状体谷氨酸能突触输入，这与 DA 耗竭诱导的纹状体神经元损伤的病理过程有关。
