Dodel R C, Du Y, Bales K R, Ling Z, Carvey P M, Paul S M
Department of Pharmacology and Toxicology, Indiana University School of Medicine, 655 Barnhill Drive, Indianapolis, IN 46202, USA.
Brain Res Mol Brain Res. 1999 Jan 22;64(1):141-8. doi: 10.1016/s0169-328x(98)00318-0.
Neurotoxicity induced by 6-hydroxydopamine (6-OHDA) is believed to be due, in part, to the production of reactive oxygen species (ROS) and/or an inhibition of mitochondrial function. However, little is known about the ensuing intracellular events which ultimately result in cell death. Here we show that exposure to relatively low concentrations of 6-OHDA induces apoptosis of cerebellar granule neurons (CGN). 6-OHDA-induced apoptosis of CGN is associated with activation of a caspase-3-like protease. Western blots of cytosolic extracts from 6-OHDA-treated CGN reveal a translocation of cytochrome c from mitochondria to the cytosol, which precedes activation of the protease detected by Ac-DEVD-pNA. DNA laddering can be blocked by caspase inhibitors zVAD-FMK and Ac-DEVD-CHO, however cell death can only be attenuated for a short time period in the presence of these inhibitors. Our data suggest that 6-OHDA-induced apoptosis of CGN involves activation of a caspase-3-like protease. In contrast to the neurotoxicity induced by MPP+, however, the peptide inhibitors zVAD-FMK and Ac-DEVD-CHO can only attenuate early neuronal death induced by 6-OHDA. At later time points, neuronal death lacking DNA laddering occurs even in the presence of the peptide inhibitor zVAD-FMK or Ac-DEVD-CHO.
6-羟基多巴胺（6-OHDA）诱导的神经毒性被认为部分归因于活性氧（ROS）的产生和/或线粒体功能的抑制。然而，对于最终导致细胞死亡的后续细胞内事件却知之甚少。在此我们表明，暴露于相对低浓度的6-OHDA会诱导小脑颗粒神经元（CGN）凋亡。6-OHDA诱导的CGN凋亡与一种类半胱天冬酶-3蛋白酶的激活有关。对经6-OHDA处理的CGN的胞质提取物进行蛋白质免疫印迹分析显示，细胞色素c从线粒体转位至胞质溶胶，这发生在通过Ac-DEVD-pNA检测到的蛋白酶激活之前。DNA梯状条带可被半胱天冬酶抑制剂zVAD-FMK和Ac-DEVD-CHO阻断，然而在这些抑制剂存在的情况下，细胞死亡只能在短时间内得到缓解。我们的数据表明，6-OHDA诱导的CGN凋亡涉及一种类半胱天冬酶-3蛋白酶的激活。然而，与MPP +诱导的神经毒性不同，肽抑制剂zVAD-FMK和Ac-DEVD-CHO只能减轻6-OHDA诱导的早期神经元死亡。在较晚的时间点，即使在肽抑制剂zVAD-FMK或Ac-DEVD-CHO存在的情况下，也会发生缺乏DNA梯状条带的神经元死亡。
