Lee So Yeon, Moon Younghye, Hee Choi Dong, Jin Choi Hyun, Hwang Onyou
Department of Biochemistry and Molecular Biology, University of Ulsan College of Medicine, 388-1 Pungnap-dong, Songpa-ku, Seoul, 138-736, Korea.
Neurobiol Dis. 2007 Jan;25(1):112-20. doi: 10.1016/j.nbd.2006.08.024. Epub 2006 Oct 16.
We determined whether tetrahydrobiopterin(BH4), an endogenous cofactor for dopamine(DA) synthesis, causes preferential damage to DArgic neurons among primary cultured rat mesencephalic neurons and whether the death mechanism has relevance to Parkinson's disease (PD). DArgic neurons were more vulnerable to BH4 than non-DArgic neurons, exhibiting sensitivity at lower concentrations, evident by morphological and neurotransmitter uptake studies. BH4-exposed DArgic neurons showed (1) increased TUNEL staining and activated caspase-3 immunoreactivity, indicative of apoptotic death; (2) mitochondrial membrane potential loss and increased cytosolic cytochrome c, suggesting mitochondrial dysfunction; (3) increased level of oxidized proteins and protection by antioxidants, indicative of oxidative stress; and (4) increased ubiquitin immunoreactivity, suggesting alteration of protein degradation pattern. Percent of cells positive for these parameters were much higher for DArgic neurons, demonstrating preferential vulnerability. Therefore, the DArgic neuronal damage induced by BH4, the molecule synthesized and readily upregulated in DArgic neurons and activated microglia, suggests physiological relevance to the pathogenesis of PD.
我们确定了多巴胺（DA）合成的内源性辅助因子四氢生物蝶呤（BH4）是否会对原代培养的大鼠中脑神经元中的多巴胺能神经元造成选择性损伤，以及死亡机制是否与帕金森病（PD）相关。多巴胺能神经元比非多巴胺能神经元对BH4更敏感，在较低浓度下即表现出敏感性，这在形态学和神经递质摄取研究中很明显。暴露于BH4的多巴胺能神经元表现出：（1）TUNEL染色增加和活化的半胱天冬酶-3免疫反应性，表明细胞凋亡死亡；（2）线粒体膜电位丧失和胞质细胞色素c增加，提示线粒体功能障碍；（3）氧化蛋白水平升高以及抗氧化剂的保护作用，表明存在氧化应激；（4）泛素免疫反应性增加，提示蛋白质降解模式改变。多巴胺能神经元中这些参数阳性细胞的百分比要高得多，表明存在选择性易损性。因此，由BH4诱导的多巴胺能神经元损伤，这种在多巴胺能神经元和活化的小胶质细胞中合成并易于上调的分子，提示其与PD发病机制具有生理相关性。
