蛋白酶体抑制剂对中脑脑片的毒性作用及其机制研究

The toxic effects of proteasomal inhibitor on slices of midbrain of rat

目的:观察蛋白酶体抑制剂对体外培养的大鼠中脑脑片黑质多巴胺(DA)能神经元的早期毒性作用,利用这种新型的组织模型探讨蛋白酶体功能异常在帕金森(PD)发病中的作用。方法:制备Wistar大鼠体外中脑黑质脑片的长期培养体系,加入蛋白酶体抑制剂lactacystin(0.1,0.5,1.0,5.0μmol/L)作用24 h后,测定培养基中乳酸脱氢酶(LDH)活力水平观察脑片活力。TH免疫组化观察黑质细胞变性缺失,α-synuclein免疫组化观察α-synuclein的表达,TUNEL法检测多巴胺能神经元凋亡。结果:经0.1,0.5,1.0和5.0μmol/L浓度的lactacystin作用24 h后,脑片黑质部位TH阳性神经元数量减少,α-synu-clein表达率增加,凋亡检测显示,5.0μmol/L的lactacystin组部分黑质细胞出现TUNEL染色阳性。结论:蛋白酶体抑制剂lactacystin对脑片中DA能神经元具有毒性作用,能诱导黑质细胞凋亡,其作用具有浓度依赖性。蛋白酶体功能缺陷在帕金森病发病机制中可能发挥重要作用。

Objective： To observe the early neurotoxicity of proteasomal inhibitor on dopaminergic neurons in cultured slices of the midbrain and to explore the role of proteasome dysfunction in the pathogenesis of Parkinson＇s disease. Methods： A long-term midbrain slice culture system of Wistar rats was established, after proteasomal inhibitor, lactacystin （0.1 μmol/L,0.5 μmol/L, 1.0 μmol/L,5.0 μmol/L） was added into the culture system for 24h, the vitality of the slices were identified by measurement of lactate dehydrogenase （LDH） released into the medium from the slices. The loss and degeneration of nigral neurons were investigated by tyrosine hydroxylase immunohistochemistry, α-synuclein expression was observed by α-synuclein immunohistochemistry. The apoptosis of dopaminergic neurons was examined by TUNEL stain. Results： After cultured with proteasomal inhibitor lactacystin （0.1 μmol/L,0.5 μmol/L, 1.0 μmol/L and 5.0 μmol/L） for 24 hours, the numbers of tyrosine hydroxylase positive cells in substantia nigra decreased and the expression of α - synuclein increased. The measurement of apoptosis showed that some nigra neurons revealed positive TUNEL staining in 5.0 μmol/L lactacystin group. Conclusion： Proteasomal inhibitor lactacystin has toxic effect to dopaminergic neurons on midbrain slices and may induce apoptosis of nigral neurons, which has close relationship with the concentration of lactacystin. Proteasome dysfunction may play an important role in the pathogenesis of Parkinson＇s disease.