Zn^(2+)对鸡脑mRNA表达在卵母细胞膜上的GABA及KA受体的调制作用  

Zinc modulation of Oocyte GABA Receptors and KA Receptors through Chicken Brain Expression

作　　者：王钦文[1] 刘智胜[1] 常岚[1] 王凤[1] 

机构地区：[1]武汉市儿童医院儿研所分子生物室

出　　处：《郧阳医学院学报》1998年第3期125-130,共6页Journal of Yunyang Medical College

摘　　要：目的：探讨Ｚｎ２＋和氨基酸类递质之间是否存在内在关系或相互作用。方法：实验以盐酸胍方法抽提鸡脑ｍＲＮＡ，通过微量注射把信使核糖酸（ｍＲＮＡ）导入卵母细胞，利用卵母细胞的基因表达系统进行表达。应用双电极电压钳方法研究所表达的受体。结果：（１）γ－氨基丁酸（ＧＡＢＡ）及红藻氨酸（ＫＡ）受体在卵母细胞膜上表达明显。施加相应的激动剂均能引起一剂量依赖的内向电流，其幅值分别高达２９４±６．４ｎＡ和３０９．５±４．９ｎＡ，相应的拮抗剂荷包牡丹碱（ｂｉｃｕｃｕｌｉｎｅ）和６－氰基－７－硝基喹恶啉土卫四（ＣＮＯＸ）可阻断其电流，而阴性对照无此现象。（２）剂量效应曲线显示Ｚｎ２＋的浓度为３０ｍｍｏｌ／Ｌ时开始抑制３００ｍｍｏｌ／Ｌ的ＫＡ诱导电流。半抑制浓度（ＩＣ５０）为７１０ｍｍｏｌ／Ｌ。（３）Ｚｎ２＋在ｎｍｏｌ／Ｌ级浓度时即对ＧＡＢＡ诱导电流有抑制作用，ＩＣ５０为２５ｍｍｏｌ／Ｌ。（４）Ｚｎ２＋的这种抑制作用是可逆的，即去除灌流液中的Ｚｎ２＋后，ＫＡ及ＧＡＢＡ诱导电流恢复到原来大小。结论：Ｚｎ２＋可能作为一种神经调制物通过非竞争性抑制来调制ＧＡＢＡ及ＫＡ受体。Objective:To decide whether Zn and amino acid transimitters are interrelated.Methods:GABA and KA receptors were expressed in the Xenopus Laevis oocytes and investigated with two electrode voltage-clamp technique after the injection of chicken mRNA which was isolated by guinidine hydrochloride-phenol chloroform extraction.Results:The expressions of the receptors were obvious.The average amplitudes of GABA - and KA -induced current were 194.6±6.4 nA and 309.5±4.9 nA respectively.Zinc began to inhibit GABA - induced current when its concentration reached 10 mmol/L,with a EC 50 of 710 mmol/L.The lowest concentration of its inhibition of KA - induced current was 30 mmol/L and the EC50 was 25 mmol/L.Conclusion:As a neuromodulator,zinc can inhibit GABA and KA receptors in a non-competitive manner.

关 键 词：氨基酸递质 锌离子 GABA受体 KA受体 神经调制 

分 类 号：Q422[生物学—神经生物学] Q581[生物学—生理学]