淀粉样β蛋白对表达的鼠脑乙酰胆碱受体功能的影响

Studies on the effects of nanomolar amyloid β protein on the expressed acetylcholine receptors in Xenopus oocytes

目的 观察淀粉样 β蛋白 (Aβ)对表达的鼠脑乙酰胆碱 (ACh)受体功能的影响 ,探讨Aβ和乙酰胆碱受体介导的阿尔茨海默病 (AD)发病机理。方法 将提取的 3个月龄鼠的脑乙酰胆碱受体mRNA注射到非洲爪蟾卵母细胞进行受体表达 ,采用双电极电压钳位技术记录表达的神经递质受体通道电流 ,了解其电流特性并观察淀粉样 β蛋白 1 40 (Aβ1 4 0 )对其的影响。结果 表达到爪蟾卵母细胞膜上的ACh受体为M型ACh受体 ,其激活电流为内向震荡型电流 ,平衡电位为 - 2 2 7mV ,载流离子为氯离子。 2 0nmol/LAβ1 4 0 作用 12h后ACh受体峰电流由 (138± 2 9)nA降低为 (12 5± 2 3)nA ,差异有显著性 (P <0 0 5 ) ;作用 96h后峰电流由 (12 5± 2 3)nA降低为 (94± 2 3)nA ,差异有非常显著性 (P <0 0 1)。 6 0nmol/LAβ1 4 0 的作用更明显 ,作用 12h后电流峰值由 (138± 2 9)nA降为 (90± 2 3)nA ,差异有非常显著性 (P <0 0 1)。同时还观察到 10 -4 mmol/L维生素E能对抗Aβ1 4 0 的效应。结论 纳摩尔级的淀粉样 β蛋白对乙酰胆碱受体功能的影响表现为抑制效应 ,提示AD脑胆碱能功能障碍与淀粉样 β蛋白有关。

Objective It was designed to investigate the effect of β amyloid protein on the functions of expressed acetylcholine receptors in Xenopus oocytes Methods Messenger RNA was taken from 3 month old Wistar rats brains with promega kits and microinjected into Xenopus oocytes for receptor expression The currents of expressed receptors and the effect of Aβ 1 40 on them were detected with double electrode voltage clamp technique Results ACh receptors were successively expressed in Xenopus oocytes Its activating currents detected with voltage clamp were characterized by an inward oscillating current, which was carried by chloride ions Aβ 1 40 with both 20 nmol/L and 60 nmol/L had inhibitory effects on the expressed ACh receptors, which showed a significantly decreased peak current ( P <0 05) without any changes of current characteristics Vitamin E (10 -4 mmol/L) had an antagonistic effect on Aβ′s effect Conclusion Nanomolar grade of amyloid β protein has inhibitory effect on the functions of ACh receptors, which has significant meaning in the pathophysiology of Alzheimer′s disease