Lotharius J, Dugan L L, O'Malley K L
Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
J Neurosci. 1999 Feb 15;19(4):1284-93. doi: 10.1523/JNEUROSCI.19-04-01284.1999.
Oxidative stress is thought to contribute to dopaminergic cell death in Parkinson's disease (PD). The neurotoxin 6-hydroxydopamine (6-OHDA), which is easily oxidized to reactive oxygen species (ROS), appears to induce neuronal death by a free radical-mediated mechanism, whereas the involvement of free radicals in N-methyl-4-phenylpyridinium (MPP+) toxicity is less clear. Using free radical-sensitive fluorophores and vital dyes with post hoc identification of tyrosine hydroxylase-positive neurons, we monitored markers of apoptosis and the production of ROS in dopaminergic neurons treated with either 6-OHDA or MPP+. Annexin-V staining suggested that 6-OHDA but not MPP+-mediated cell death was apoptotic. In accordance with this assignment, the general caspase inhibitor Boc-(Asp)-fluoromethylketone only blocked 6-OHDA neurotoxicity. Both toxins exhibited an early, sustained rise in ROS, although only 6-OHDA induced a collapse in mitochondrial membrane potential temporally related to the increase in ROS. Recently, derivatives of buckminsterfullerene (C60) molecules have been shown to act as potent antioxidants in several models of oxidative stress (Dugan et al., 1997). Significant, dose-dependent levels of protection were also seen in these in vitro models of PD using the C3 carboxyfullerene derivative. Specifically, C3 was fully protective in the 6-OHDA paradigm, whereas it only partially rescued dopaminergic neurons from MPP+-induced cell death. In either model, it was more effective than glial-derived neurotrophic factor. These data suggest that cell death in response to 6-OHDA and MPP+ may progress through different mechanisms, which can be partially or entirely saved by carboxyfullerenes.
氧化应激被认为与帕金森病（PD）中多巴胺能细胞死亡有关。神经毒素6-羟基多巴胺（6-OHDA）容易氧化为活性氧（ROS），似乎通过自由基介导的机制诱导神经元死亡，而自由基在N-甲基-4-苯基吡啶鎓（MPP +）毒性中的作用尚不清楚。我们使用对自由基敏感的荧光团和活体染料，并在事后鉴定酪氨酸羟化酶阳性神经元，监测了用6-OHDA或MPP +处理的多巴胺能神经元中的凋亡标志物和ROS产生。膜联蛋白V染色表明，6-OHDA介导的细胞死亡是凋亡性的，而MPP +介导的细胞死亡不是。根据这一结果，通用的半胱天冬酶抑制剂Boc-(Asp)-氟甲基酮仅阻断6-OHDA的神经毒性。两种毒素均表现出早期、持续的ROS升高，尽管只有6-OHDA诱导线粒体膜电位崩溃，且这与ROS增加在时间上相关。最近，已证明巴基球（C60）分子的衍生物在几种氧化应激模型中可作为有效的抗氧化剂（Dugan等人，1997年）。在这些PD体外模型中，使用C3羧基富勒烯衍生物也观察到了显著的、剂量依赖性的保护水平。具体而言，C3在6-OHDA模型中具有完全保护作用，而在MPP +诱导的细胞死亡模型中，它只能部分挽救多巴胺能神经元。在任一模型中，它都比胶质细胞源性神经营养因子更有效。这些数据表明，对6-OHDA和MPP +的细胞死亡可能通过不同机制进展，而羧基富勒烯可以部分或完全挽救这些机制。
