Ren Chao, He Kai-Jie, Hu Hua, Zhang Jin-Bao, Dong Li-Guo, Li Dan, Chen Jing, Mao Cheng-Jie, Wang Fen, Liu Chun-Feng
Department of Neurology and Clinical Research Center of Neurological Disease, the Second Affiliated Hospital of Soochow University, Suzhou, China.
Jiangsu Key Laboratory of Neuropsychiatric Diseases and Institute of Neuroscience, Soochow University, Suzhou, China.
J Parkinsons Dis. 2022;12(1):295-314. doi: 10.3233/JPD-212640.
Previous investigations have suggested that decreased expression of glutamate transporter-1 (GLT-1) is involved in glutamate excitotoxicity and contribute to the development of Parkinson's disease (PD), GLT-1 is decreased in animal models of PD. GLT-1 is mainly expressed in astrocytes, and the striatum is a GLT-1-rich brain area.
The aim was to explore the function and mechanism of astrocytic GLT-1 in PD-like changes.
In the study, PD-like changes and their molecular mechanism in rodents were tested by a behavioral assessment, micro-positron emission tomography/computed tomography (PET/CT), western blotting, immunohistochemical and immunofluorescence staining, and high performance liquid chromatography pre-column derivatization with O-pthaldialdehida after downregulating astrocytic GLT-1 in vivo and in vitro.
In vivo, after 6 weeks of brain stereotactic injection of adeno-associated virus into the striatum, rats in the astrocytic GLT-1 knockdown group showed poorer motor performance, abnormal gait, and depression-like feature; but no olfactory disorders. The results of micro-PET/CT and western blotting indicated that the dopaminergic system was impaired in astrocytic GLT-1 knockdown rats. Similarly, tyrosine hydroxylase (TH) positive immune-staining in neurons of astrocytic GLT-1 knockdown rats showed deficit in cell count. In vitro, knockdown of astrocytic GLT-1 via RNA interference led to morphological injury of TH-positive neurons, which may be related to the abnormal calcium signal induced by glutamate accumulation after GLT-1 knockdown. Furthermore, the GLT-1 agonist ceftriaxone showed a protective effect on TH-positive neuron impairment.
The present findings may shed new light in the future prevention and treatment of PD based on blocking glutamate excitotoxicity.
先前的研究表明，谷氨酸转运体-1（GLT-1）表达降低与谷氨酸兴奋性毒性有关，并促成帕金森病（PD）的发展，在PD动物模型中GLT-1表达降低。GLT-1主要在星形胶质细胞中表达，而纹状体是富含GLT-1的脑区。
探讨星形胶质细胞GLT-1在帕金森病样改变中的作用及机制。
在本研究中，通过行为学评估、微型正电子发射断层扫描/计算机断层扫描（PET/CT）、蛋白质免疫印迹法、免疫组织化学和免疫荧光染色，以及在体内和体外下调星形胶质细胞GLT-1后采用邻苯二甲醛柱前衍生高效液相色谱法，检测啮齿动物的帕金森病样改变及其分子机制。
在体内，脑立体定向注射腺相关病毒至纹状体6周后，星形胶质细胞GLT-1基因敲低组大鼠运动性能较差，步态异常，有抑郁样特征；但无嗅觉障碍。微型PET/CT和蛋白质免疫印迹法结果表明，星形胶质细胞GLT-1基因敲低大鼠的多巴胺能系统受损。同样，星形胶质细胞GLT-1基因敲低大鼠神经元中酪氨酸羟化酶（TH）阳性免疫染色显示细胞计数减少。在体外，通过RNA干扰敲低星形胶质细胞GLT-1导致TH阳性神经元形态损伤，这可能与GLT-1敲低后谷氨酸积累诱导的钙信号异常有关。此外，GLT-1激动剂头孢曲松对TH阳性神经元损伤有保护作用。
本研究结果可能为未来基于阻断谷氨酸兴奋性毒性防治帕金森病提供新的思路。
