GDNF激活星形胶质细胞保护PD模型大鼠黑质多巴胺能神经元

探索在胶质细胞源性神经营养因子(GDNF)保护受损多巴胺(DA)能神经元过程中,星形胶质细胞的可能作用。成年大鼠右侧纹状体内注射6-羟多巴胺(6-OHDA)制备Parkinson病(PD)模型。动物模型右侧黑质内注射GDNF,于注射后第7、14和21d进行动物行为学分析,行黑质节段连续冠状石蜡切片,以抗酪氨酸羟化酶(TH)、胶质原纤维酸性蛋白(GFAP)抗体免疫组化染色,分别显示DA能神经元和激活的星形胶质细胞,光镜观察并进行细胞计数。用免疫印迹法分析注射后第21d黑质内TH、GFAP蛋白表达量,蛋白条带用图像处理仪扫描,LabWorks软件分析处理。结果显示:动物在注射GDNF后第21d,行为学功能出现显著性恢复;TH阳性神经元数量显著增加;在检测的各时间点均可观察到大量的GFAP阳性细胞;TH、GFAP的蛋白表达量显著高于对照组。以上结果提示,黑质内注射GDNF可能通过激活了的星形胶质细胞保护PD模型大鼠黑质DA能神经元。

GDNF PROTECTS THE DA NEURONS IN THE SUBSTANTIA NIGRA OF PD MODEL RATS BY ACTIVATING ASTROCYTES

This study is to explore the possible role of astrocytes in the process for the glial cell line-derived neurotrophic factor (GDNF) to protect the dopaminergic neurons (DA neurons) in Parkinson’s disease (PD) model rats. The PD rats were prepared by steriotaxic injection of 6-OHDA into right striatum, with the qualified models screened by behavioral analysis. Having survived for 7 days after the injection of 6-OHDA, GDNF was injected into the ipsilateral substantia nigra (SN). 7, 14 and 21 days after GDNF injection, following behavioral test, rats were sacrificed in groups to get the segment of SN fixed, embedded and coronally sectioned continuously. The sections were processed by immunohistochemistry to label the DA neurons with anti-tyrosine hydroxylase (TH) monoclonal antibody and the activated astrocytes with anti-glial fibrillary acidic protein (GFAP) monoclonal antibody. The labeled cells were counted under microscope and the data were analyzed statistically. Western blot assay was used to examine the protein expressions of TH and GFAP in SN of rats on the 21st day, of which the bands on the filter were scanned and analyzed with an image analyzer of LabWorks. The results indicated that the lesion-induced behavioral asymmetries recovered rapidly and the TH positive neurons increased in number in the SN 21 days after intranigra GDNF injection. It was also found that the GFAP-positive cells were markedly increased in the GDNF-treated model rats, with the protein expressions of TH and GFAP being significantly higher than that in the control model groups. It is suggested that intranigral infusion of GDNF can activate astrocytes to protect the DA neurons from subsequent 6-hydroxydopamine neurotoxicity.