Neurotropin拮抗6-OHDA诱导大鼠早期黑质多巴胺能神经元的凋亡

Antagonistic Effect of Neurotropin on Apoptosis of Dopaminergic Cells in Substantia Nigra in Rats Induced by 6-Hydroxydopamine

【目的】探讨神经托平(neurotropin)对6-OHDA诱导的SD(Sprague-Dawley)大鼠黑质多巴胺能神经元极早期凋亡的拮抗作用。【方法】实验组SD大鼠,按完全随机设计分3组,每组16只,分别用神经托平15、30、45U·kg-1·d-1腹腔内注射,对照组(32只)用等体积的生理盐水腹腔内注射。2周后用6-OHDA立体定向注射于大鼠纹状体区。在6h、12h、24h、48h、72h、96h、1周及2周时采用原位末端标记法(TUNEL)检测黑质细胞的凋亡,用流式细胞仪检测凋亡率,用免疫组化法检测纹状体区多巴胺能神经纤维的含量的变化。【结果】对照组在6-OHDA作用后的6h即可检测到黑质细胞凋亡,在48h达到高峰,凋亡率6.4%±0.2%;神经托平30、45U·kg-1·d-1预处理后则可降低细胞凋亡(P<0.05),其中45U·kg-1·d-1预处理组在48h仅为2.3%±0.1%,与实验组比有统计学意义,同时纹状体区多巴胺能神经纤维含量的减少较对照组亦有统计学意义(P<0.05);而15U·kg-1·d-1组则无明显效果。【结论】大剂量神经托平可拮抗神经毒性物质对黑质神经元的凋亡作用,避免了投射至纹状体区多巴胺能神经递质的减少,为今后探讨帕金森病的防治提供了重要的理论依据。

ObjectiveTo observe the antagonistic effect of neurotropin to the acute apoptosis in nigral dopaminergic neurons following a 6-hydroxydopamine lesion in Sprague-Dawley (SD) rats. MethodsThe experimental group of SD rats were intra-abdominally injected neurotropin previously in the dosages of 15,30,45 U·kg-1·d-1, the control group was given the isovolumic normal sodium in the same way. Two weeks later, the rats were intracerebral stereotaxically injected of 6-hydroxydopamine (6-OHDA), then the apoptosis of nigral dopaminergic neurons were examined at 6 h, 12 h, 24 h, 48 h, 72 h, 96 h, 1 week, and 2 weeks after lesioning, using terminal deoxynucleotidyl transferase-mediated DUTP nick end labeling (TUNEL) method. Flow cytometry was used to examine the percentage of apoptosis. Furthermore, content of dopaminergic fibers in corpus striatum were detected using tyrosine hydroxylase immunohistochemistry. ResultsThe apoptosis of dopaminergic neurons in substantia nigra was detected 6 h immediately after 6-OHDA injection in control group, and the percentage of apoptosis reached the highest level (6.4%±0.2%) at 48 h, while lower apoptosis was detected in the group treated previously by neurotropin in the dosages of 30 and 45 U·kg-1·d-1 (P< 0.05), and the apoptosis in the group of 45 U·kg-1·d-1 treated group was only 2.3%±0.1%at 48 h, there was a significant difference in the content of dopaminergic fibers in striatum decreased compared with the control group as well. But no effect in the group of 15 U·kg-1·d-1 was observed. ConclusionsLarge dosage of neurotropin is against the apoptosis of nigral dopaminergic neurons in acute time course suffered by neurotoxocity, avoiding the decrease of dopaminergic neurotransmitters in corpus striatum, which provided important theoretical evidences for searching an effective way to prevent and cure Parkinson′s disease.