多巴胺对PC12细胞的双重影响

本实验运用PC12细胞，研究不同浓度多巴胺（dopamine,DA)对细胞的影响，同时利用兼具促进多巴胺释放和抑制多巴胺摄取双重作用的安排它命（amphetamine,AMP)观察胞内外多巴胺对细胞的不同作用。结果显示；胞外高浓度DA能引起细胞抗氧化能力下降，胞内游离Ca^2 浓度上升。细胞存活率大幅度降低，部分细胞出现凋亡；低浓度DA对细胞存活率无明显影响，而使细胞抗氧化能力有一定提高，长时间安非它命单独作用也可引起细胞存活率下降，并伴随胞内GSH水平降低；安非它命与多巴胺共同作用在一定程度上可导致细胞内抗氧化物质水平低于多巴胺单独作用，表明细胞内一定浓度DA可以维持或提高细胞抗氧化物质水平。结果提示，脑内同样存在的多巴胺神经元对DA重摄取功能下降，胞外氧化应激增强，可能是引起脑内多巴胺神经元退行性病变的重要原因之一。

Double action of dopamine on PC12 cells]

PC12 cell line was used to examine the cytotoxicity of dopamine (DA). The higher dose of DA (400micromol/L) greatly reduced cell survival rate and induced apoptosis,meanwhile the lower dose (100micromol/L) had less cytotoxicity. Further studies showed that AMP (100micromol/L) were not cytotoxic at 24h, but decreased cell survival rae to 78% at 72h compared to control, and also exacerbate the cytotoxicity of DA (100micromol/L) at 72h. By determine the action of GSH level and SOD activity, we found that appropriate intracellular DA may be advantageous to protect cells from the toxicity of higher dose DA. The intracellular calcium concentration showed that DA's toxicity increased intracellular concentration of calcium. The results suggest that it was the extracellular DA that made cytotoxicity by decreasing cell's possibility of antioxide and increasing intracellular free calcium.