DOPAMINE-INDUCED NEUROTOXICITY IN A CATECHOLAMINERGIC CELL LINE

大脑中过度活跃的多巴胺能神经元被认为是 在精神分裂症病因学中的重要作用。 已经 假设，长期暴露于儿茶酚胺神经元， 过量的多巴胺或多巴胺的氧化代谢物可 产生神经元损伤，细胞死亡，并部分负责 精神分裂症的一些负面症状 儿茶酚胺已经被 显示对原发性肾上腺素和多巴胺神经元具有神经毒性 培养（J Neurosci Res 26：428，1990; J Pharmacol Exp Ther 262：1274， 1992年）。 我们正在评估多巴胺的神经毒性作用， Chikaraishi及其同事开发的克隆细胞系（J Neurosci 13：1280，1993）。 该细胞系来源于酪氨酸羟化酶 从携带SV的转基因小鼠的CNS获得的阳性肿瘤 大鼠转录控制下的40 T抗原癌基因 酪氨酸羟化酶基因 我们发现，将CATH. a细胞与 多巴胺产生剂量依赖性细胞死亡， 浓度的多巴胺（500 mM）杀死80%的细胞，相对于 未经处理的细胞 发现这种细胞死亡是由于细胞凋亡， 使用凝胶电泳技术通过DNA片段化进行评价， 流式细胞术分析。 细胞凋亡似乎是由多巴胺引起的 自氧化，因为多巴胺后细胞内过氧化物增加 处理，过氧化氢酶抑制细胞死亡。 Bcl-2水平 以剂量依赖性方式减少，以响应多巴胺。这些 研究结果表明，多巴胺的氧化产物导致 神经毒性，并可调节bcl-2水平。bcl-2的调节可能 在阻止多巴胺神经元的神经变性方面很重要， 帕金森氏症。

Overactive dopaminergic neurons in the brain are thought to play an important role in the etiology of schizophrenia. It has been hypothesized that prolonged exposure of catecholamine neurons to excessive levels of dopamine or the oxidative metabolites of dopamine may produce neuronal damage, cell death, and be partially responsible for some of the negative symptoms of schizophrenia. Catecholamines have been shown to be neurotoxic to norepinephrine and dopamine neurons in primary culture (J Neurosci Res 26:428, 1990; J Pharmacol Exp Ther 262:1274, 1992). We are evaluating the neurotoxic effects of dopamine by using a clonal cell line developed by Chikaraishi and co-workers (J Neurosci 13:1280, 1993). This cell line was derived from a tyrosine hydroxylase positive tumor obtained from the CNS of transgenic mice carrying the SV 40 T antigen oncogene under the transcriptional control of the rat tyrosine hydroxylase gene. We found that incubation of CATH.a cells with dopamine produced dose-dependent cell death, with the highest concentration of dopamine (500 mM) killing 80% of the cells relative to untreated cells. This cell death was found to be due to apoptosis as evaluated by DNA fragmentation using gel-electrophoresis techniques and flow cytometry analysis. Apoptosis appeared to be produced by dopamine autoxidation, since intracellular peroxides increase after dopamine treatment, and cell death was inhibited by catalase. Bcl-2 levels decrease in a dose dependent manner in response to dopamine. These findings suggest that the oxidative products of dopamine cause neurotoxicity and can regulate bcl-2 levels. The regulation of bcl-2 may be important in deterring the neurodegeneration of dopamine neurons in Parkinson's disease.