尼古丁对PD大鼠黑质多巴胺能神经元变性的影响

目的 探讨尼古丁对帕金森病(PD)大鼠黑质多巴胺能神经元变性的影响及其机制. 方法 45只大鼠随机分为PBS对照组(CON)、生理盐水+ 脂多糖(NS)组、尼古丁+脂多糖(NIC)组,每组15只.黑质内立体定向注射脂多糖(LPS)或PBS后24h,免疫印迹法检测黑质诱导性一氧化氮合酶(iNOS)蛋白表达变化;黑质注射药物后14d,采用免疫组织化学法观察大鼠黑质酪氨酸羟化酶(TH)阳性神经元数量及OX-42阳性细胞形态学变化,RT-PCR及免疫印迹检测黑质TH mRNA及TH蛋白的表达水平. 结果 与CON组相比,NS组大鼠黑质iNOS表达明显增多,TH阳性神经元、TH mRNA及TH蛋白明显减少,小胶质细胞大多呈胞体大突起短粗的形态;NIC组黑质iNOS表达明显少于NS组,黑质TH阳性神经元、TH mRNA及TH蛋白表达较NS组明显增多,大部分小胶质细胞呈胞体小,突起细长的形态. 结论 尼古丁可以减轻LPS介导的多巴胺能神经元变性,对多巴胺能神经元有保护作用,其保护机制与抑制小胶质细胞激活、减少iNOS的表达有关.

Effect of nicotine on the degeneration of dopaminergic neurons in the substantia nigra of PD rats

Objective To explore the effect of nicotine on the degeneration of dopaminergic neurons in PD rats. Methods Forty-five SD rats were randomly divided into three groups: PBS group (CON), normal saline + LPS ( NS ) group and nicotine +LPS ( NIC ) group. On 24 hours after LPS or PBS injection, inducible nitric oxide synthase ( iNOS ) protein expression was examined by immunoblotting. ON 14d after LPS or PBS injection, the numbers of tyrosine hydroxylase ( TH ) positive neurons and morphological changes of OX-42 positive cells in the substantia nigra(SN) were observed by immunohistochemistry. TH mRNA and TH protein expressions were examined by RT-PCR or immunoblotting. Results Compared with CON group, iNOS protein increased markedly 24 hours after LPS injection in NS group. TH positive neurons, TH mRNA and TH protein in the SN decreased remarkably 14 days after nigrainjiection. Most of microlglial showed big cell body with thicker and shorter processes. However, nicotine reversed the above changes, Compared with NS group, TH positive neurons, TH mRNA and TH protein in the SN increased remarkably in NIC. Besides, most microglia showed small cell body with slim and long processes. Conclusion Nicotine could prevent LPS-induced degeneration of DA neurons, probably because of that the pretreatment with nicotine blocks the activation of microglia and the expression iNOS protein.