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扮演着一种 在精神分裂症病因学中的重要作用。一直以来 假设儿茶酚胺神经元长期暴露于 过量的多巴胺或多巴胺的氧化代谢产物可能 造成神经元损伤，细胞死亡，并对 精神分裂症的一些负面症状。儿茶酚胺一直是 显示对去甲肾上腺素和多巴胺神经元有神经毒性 培养(神经科学杂志26：428,1990；药理实验杂志262：1274， (1992年)。我们正在评估多巴胺的神经毒性效应。 Chikaraishi和他的同事(J Neurosci)建立的克隆细胞系 13：1280,1993)。该细胞系来源于一种酪氨酸羟化酶。 从携带SV的转基因小鼠的中枢神经系统获得阳性肿瘤 大鼠转录调控下的40T抗原癌基因 酪氨酸羟基酶基因。我们发现CATH.a细胞与 多巴胺引起剂量依赖性的细胞死亡，最高 浓度为500 mM的多巴胺可杀死80%的细胞 未经处理的细胞。这种细胞死亡被发现是由于细胞凋亡所致 通过使用凝胶电泳技术进行DNA片段分析和 流式细胞仪分析。细胞凋亡似乎是由多巴胺引起的。 自氧化作用，因为多巴胺后细胞内过氧化物质增加 细胞死亡被过氧化氢酶抑制。BCL-2水平 以剂量依赖的方式减少对多巴胺的反应。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bcl2水平。Bc1-2的调控可能 在阻止脑内多巴胺神经元退行性变中起重要作用 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.