氯化锰对大鼠中脑多巴胺能神经元毒性的研究

本文通过锰诱导多巴胺能神经元凋亡及其可能的神经化学机制的研究 ,进而探讨锰中毒与帕金森病发病的相互关系。分离培养大鼠中脑黑质多巴胺能神经元用不同剂量 Mn Cl2 处理后 ,用荧光染料进行染色 ,观察了凋亡神经元数量。用腹腔注射及脑内单侧注射 Mn Cl2 染毒方法处理大鼠 ,并采用脑内微透析技术和高效液相色谱 -电化学方法 (HPLC-ECD)在活体检测了术后不同时间的纹状体细胞外液中 DA及其代谢产物 DOPAC、HVA以及 5 -HT的代谢产物 5 -HIAA等的含量 ;同时作丙二醛含量和过氧化物歧化酶活性检测。结果发现 ,凋亡神经元的细胞核缩小、不规则、染色质呈块状深染 ,凋亡细胞数量随 Mn Cl2 剂量升高而增多。Mn Cl2 脑内注射侧与注射对侧相比 ,术后 4、7、10、2 0 d的 DA、DOPAC、HVA和 5 -HIAA含量均有不同程度的降低。腹腔染毒高、低剂量组 2 0 d后大鼠整体纹状体匀浆的上述指标也明显降低。此外 ,染毒大鼠纹状体中丙二醛水平随染毒剂量增高而增高 ,过氧化物歧化酶活性随染毒剂量增高却下降。以上结果表明 ,锰中毒可能是引起帕金森病发病的原因之一

THE NEURAL TOXICITY OF MANGANESE CHLORIDE ON DOPAMINERGIC NEURONS OF THE MIDBRAIN IN THE RAT

In order to find a certain relationship between manganism and pathogenesis of Parkinson's disease, Mn-induced apoptosis in dopaminergic neurons and its possible mechanism were investigated. Neurons dissociated from the substantia nigra(SN) of SD rats were treated with different dosage of MnCl 2, the apoptosis of neurons was distinguished by using the staining of fluorescent dye Hoechst 33258. The solution of MnCl 2 was stereotactically injected into the striatum of rats or into i.p. An intracerebral microdialysis coupled with HPLC-ECD, was used to measure the striatal levels of DA and its metabolites(DOPAC, HVA), as well as the metabolite of 5-HT (5-HIAA) in vivo at different time after microinjection. Lipid peroxidant product MDA in striatum, SOD activity in RBC and striatum were also measured 7 days after Mn 2 i.p. injection. It was seen that the dimensions of nuclei in apoptotic cells diminished clearly and their shapes were irregular with fine chromatin aggregates and darkly stained. The number of apoptotic cells increased with dosage of Mn 2 . The extracellular levels of ipsilateral striatal DA, DOPAC, HVA, 5-HIAA decreased to some extent as compared with those of the contralateral striatum at 4, 7, 10, 20 days after injection. DA, DOPAC and HVA levels in striatal homogenate in stereotactically or i.p. injected groups decreased, too, compared with control group. Striatal MDA levels increased and SOD activity decreased significantly, while SOD activity of RBC was not affected. The results in the present study indicate that the toxicity of manganese is probably one of pathogenesis of PD.