尼古丁抑制脂多糖诱导的原代多巴胺能神经元变性及相关机制

Nicotine suppresses lipopolysaccharide-induced microglia activation and degeneration of dopaminergic neurons

目的： 观察尼古丁对脂多糖（LPS）诱导的胎鼠中脑小胶质细胞激活的影响及对其白介素6（IL-6）分泌的影响,以探讨尼古丁对中脑多巴胺（DA）能神经元的保护机制.方法： 取孕14d SD大鼠,胎鼠中脑腹侧区组织,混合培养中脑神经元-胶质细胞,Elisa检测细胞不同时间点分泌IL-6的水平;免疫细胞化学术检测小胶质细胞特异的钙结合蛋白（Iba1）和标记DA能细胞的酪氨酸羟化酶（TH）的阳性细胞数.结果： 经LPS激活的小胶质细胞胞体增大,活化标记物Ibal表达上调;DA能细胞的数目减少,突起受损.Elisa方法测定显示10ng/ml LPS致小胶质细胞在8、24和72h分泌IL-6的量均增高;在尼古丁（100μmol/L）预处理组,小胶质细胞的激活被抑制,TH免疫阳性的多巴胺能神经元的数量增加,LPS＋尼古丁组分泌IL-6的量减少,在不同时间点（8、24和72h）与LPS组比较差异均有统计学意义.结论： 尼古丁可抑制小胶质细胞的激活,保护多巴胺能神经元,抑制小胶质细胞炎性因子的释放可能是其主要保护机制.

Objective： To observe nicotine on lipopolysaccharide （LPS）-induced microglia activation in primary neuron-gila cultures and cytokine IL-6 secretion and to explore the possible mechanism of nicotine＇s neuroprotective effect in Parkinson＇s disease. Methods： The ventral mesencephalic tissues from embryonic day 14 Sprague-Dawley rats were dissected and the mixed neuron-glial cells were cultured, and then treated with or without nicotine and/or LPS for 8 h, 24 h and 72 h for measuring IL-6 and immunocytochemical detection Ibal, TH positive cells. Results.. LPS induced activation of microglia, activated microglia increased the expression of activation marker Ibal; reduced the number of TH-positive neurons and damaged its processes. 10 ng/ml LPS induced the amount of IL-6 secretion of microglia at 8 h, 24 h and 72 h, which was significantly higher than those of the control group. However, nicotine significantly attenuated these changes induced by LPS. Nicotine significantly inhibited microglia activation and IL-6 production, and increased the humber of TH neurons. Conclusion： Nicotine can protect dopaminergic neurons, which may be due to nicotine blocked activation of microglia and reduced IL-6 release of microglia.