3-硝基丙酸多次化学预处理对多巴胺能神经元的保护作用

目的探讨3-硝基丙酸（3-NP）多次化学预处理对多巴胺能神经元的保护作用及可能机制。方法应用MPTP（30mg／kg）在C57BL小鼠上复制帕金森病模型，以3-NP（20mg／kg）行预处理，检测小鼠中脑黑质凋亡率和转录因子c-Jun的阳性细胞数量及c-Jun的蛋白水平；应用MPP^＋（0．25mmol／L）在SH—SY5Y细胞制作帕金森病模型，以3-NP（0．2mmol／L）进行预处理，并将携带显性突变体c—JuncDNA片段的真核表达载体质粒pcDNA3（HA）-Jun—dn转染SH—SY5Y细胞，检测各组细胞的c-Jun表达水平及凋亡率。结果小鼠中脑黑质凋亡率：MPTP组较对照组明显升高（P〈0.01），3-NP单次、多次预处理后均明显降低（P〈0．05，P〈0．01）；c—Jun阳性细胞数：MPTP组较对照组明显增加（P〈0．05），3-NP单次预处理组与MPTP组比较无明显差异，3-NP多次预处理后明显降低（P〈0．05）；c—Jun蛋白水平：与其阳性细胞数变化一致；细胞凋亡率：MPP^＋组较对照组明显升高，3-NP单次、多次预处理组细胞凋亡率明显降低（P〈0.05，P〈0．01）；c-Jun蛋白水平变化与中脑黑质一致；经pcDNA3（HA）-Jundn转染的细胞，其c-Jun的表达较未转染细胞明显降低（P〈0．01），其凋亡率也下降（P〈0．01）。结论3-NP单次、多次预处理对多巴胺能神经元确有保护作用，多次预处理保护效果更强，其机制与抑制转录因子c-Jun的表达，降低其蛋白水平有关。

Protective effect of 3-NP repetitive preconditioning on dopaminergic neurons

Objective To investigate the protective effect of 3-NP repetitive preconditioning on dopaminergic neurons. Methods Parkinson' s disease model were made on C57BL mouse with MPTP (30 mg/kg) . 3-NP were administered to produce preconditioning before MPTP used. The apoptosis ratio and expression of c-Jun in the substantia nigra were assayed. MPP+ were used to made parkinson' s disease model in vitro. 3-NP were incubated to produce preconditioning;The fragment of dominant mutant c-JuncDNA carried by eukaryon plasmid pcDNA3 (HA) -jun-dn was transfected into SH-SY5Y cells. The expression of c-Jun and the apoptosis ratio of SH-SY5Y cells were assayed. Results In MPTP group, the ratio of apoptosis was increased significantly. After 3-NP preconditioning,apoptosis was decreased significantly and the effect of repetitive preconditioning was better than that of single preconditioning. The expression of c-Jun was increased in MPTP group and no obviously changes were observed after 3 -NP single preconditioning, but decreased after 3 -NP repetitive preconditioning. In the transfection group, the expression of c-Jun was decreased and the apoptosis ratio was lower than that without transfection group. 3-NP repetitive preconditioning could decrease the expression of c-Jun and apoptosis ratio. Conclusion 3-NP preconditioning exerts protective effect on dopaminergic neurons and the effect of repetitive preconditioning was better than single preconditioning.