脂多糖对多巴胺能神经元的损毁作用及其机制研究

目的观察脂多糖(1ipopolysaccharide．LPs)对黑质多巴胺(dopamine，DA)能神经元的损毁作用，探讨免疫机制与帕金森病(Parkinsondisease，PD)发病的相关性。方法采用立体定向术将LPS注人大鼠单侧黑质后分别于注射后2、3、4周经腹腔注射阿朴吗啡诱发动物旋转行为；采用高效液相色谱一电化学法(high performanee liquid chromatography，HPLC)测定纹状体和黑质部位DA等单胺类递质含量；采用免疫组化法检测黑质酪氨酸羟化酶(tyrosine hydroxylase，TH)阳性细胞数；采用尼(氏)染色(Nissl)观察小胶质细胞的活化和以双重免疫酶染色法观察小胶质细胞活化和诱导型一氧化氮合酶(inducible nitric oxide，iNOS)合成。结果大鼠单侧黑质注人LPS后2、3、4周，以阿朴吗啡诱发大鼠均出现旋转行为，其损伤侧纹状体和黑质DA及其代谢物含量降低了30%～70%，注射侧的黑质TH阳性细胞数减少，尤以3周和4周为甚．尼(氏)染色和双重免疫酶染色法也分别显示LPS注射侧小胶质细胞活化，同时伴有iNOS合成的增加。结论LPS对DA能神经元具有一定的损毁作用，小胶质细胞的活化及其释放的NO有可能参与该细胞死亡，提示免疫机制与PD的发病可能存在相关性。

Study on Lipopolysaccharide Injury of Dopaminergic Neurons and Its Relevant Mechanism

Objective To study lipopolysaccharide (LPS)-induced injury of dopaminergic neurons and the relevant immunity and the pathogenesis of Parkinson disease (PD).Methods Lipopolysaccharide was stereostatically injected into unilateral substantia nigra of rats.The circling behavior was observed by intraperitoneal-injection of apomorphine during the intervals of 2,3 and 4 weeks after injection.The contents of monoamine in the nigrostriatal system were measured by high performance liquid chromatography (HPLC).Tyrosine hydroxylase (TH)immunohistochemistry was used to detect midbrain dopaminergic neurons. Nissl staining indirectly indicated the activation of microglia, and at the same time the synthesis of inducible nitric oxide (iNOS) were identified by double immunity enzyme staining. Results The circling behavior ipsilateral to LPS injected-side was induced in some rats 3 and 4 weeks following injection, but not in 2 weeks. Compared with the control rats, the 30%-70% reduction of dopamine and its metabolite (DOPAC) in the lesion of striatum and substantia nigra was found at 2 ,3 and 4 weeks time groups.The marked loss of TH-positive cells in the injured substantia nigra was identified,especially 3 and 4 weeks after LPS treatment. The activation of microglia and synthesis of iNOS were also observed by Nissl staining and double immunity enzyme staining.Conclusions LPS intranigral injection could injure the dopaminergic neurons in the substantia nigra.Both activation of microglia and release of NO played an important role in the death of the neurons. Thus, it suggests that immunity may be involved in the pathogenesis of PD.