ETHANOL SENSITIVITY OF HETEROMERIC NMDA RECEPTORS - EFFECTS OF SUBUNIT ASSEMBLY, GLYCINE AND NMDAR1 MG2+-INSENSITIVE MUTANTS
ETHANOL SENSITIVITY OF HETEROMERIC NMDA RECEPTORS - EFFECTS OF SUBUNIT ASSEMBLY, GLYCINE AND NMDAR1 MG2+-INSENSITIVE MUTANTS
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DOI：
10.1016/0028-3908(94)00155-l
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发表时间：
1995-03-01
影响因子：
4.7
通讯作者：
WOODWARD, JJ
中科院分区：
文献类型：
--
作者：
MIRSHAHI, T;WOODWARD, JJ
在目前的研究中，N-甲基-D-天冬氨酸（NMDA）受体亚基的二聚体和三聚体的组合在非洲爪蟾卵母细胞中表达，并使用传统的双电极电压钳方法检查其对乙醇的敏感性。在表达NR 1/2A亚基的卵母细胞中，乙醇（25，50和100 mM）分别抑制NMDA（100 μ M）/甘氨酸（10 μ M）诱导的电流21，31和47%。在表达NR 1/2B电流的卵母细胞中，NMDA刺激的电流被抑制13%、25%和45%，而NR 1/NR 2C电流被抑制6%、11%和24%。在注射NR 1/2A/2B或NR 1/2A/2C的卵母细胞中，乙醇对NMDA刺激电流的抑制与在注射NR 1/2B或NR 1/2C的卵母细胞中观察到的分别没有显著差异。对于所有受体组合，乙醇抑制是快速的、可逆的，并且不受预孵育的影响。在没有乙醇的情况下，甘氨酸增强NMDA诱导的电流与EC（50）为1.42 μ M的NR 1/NR 2A组合和0.51 μ M的NR 1/NR 2C组合。乙醇抑制NMDA诱导的电流在所有甘氨酸浓度测试（1-100 μ M），并没有显着改变EC（50）值甘氨酸表明乙醇不竞争的甘氨酸网站上的NMDA受体。最后，当与NR 2A亚基组合表达时，测试了先前已被其他人证明具有降低的Mg 2+敏感性和Ca 2+渗透性（N616 Q和N616 R）或降低的电流幅度（F609 L）的三种NR 1突变体的乙醇敏感性。用F609 L取代野生型NR 1并没有改变受体对乙醇的敏感性。然而，NR 1（N616 Q）/NR 2A和NR 1（N616 R）/NR 2A注射的卵母细胞表现出降低的敏感性，乙醇表明，在重组NMDA受体的离子渗透特性的改变可能会影响其敏感性乙醇。
In the current study, dimeric and trimeric combinations of N-methyl-D-aspartate (NMDA) receptor subunits were expressed in Xenopus oocytes and their sensitivity to ethanol was examined using conventional two electrode voltage clamp methods. In oocytes expressing the NR1/2A subunits, ethanol (25, 50 and 100 mM) inhibited NMDA (100 mu M)/glycine (10 mu M) induced currents by 21, 31 and 47%; respectively. NMDA-stimulated currents in oocytes expressing NR1/2B currents were inhibited by 13, 25 and 45% while NR1/NR2C currents were inhibited by 6, 11 and 24%. Ethanol inhibition of NMDA-stimulated currents in oocytes injected with NR1/2A/2B or NR1/2A/2C was not significantly different from that observed in NR1/2B or NR1/2C injected oocytes, respectively. With all receptor combinations, ethanol inhibition was rapid, reversible and not altered by pre-incubation. In the absence of ethanol, glycine enhanced NMDA-induced currents with an EC(50) of 1.42 mu M for the NR1/NR2A combination and 0.51 mu M for the NR1/NR2C combination. Ethanol inhibited NMDA-induced currents at all glycine concentrations tested (1-100-mu M) and did not significantly alter the EC(50) value for glycine suggesting that ethanol does not compete for the glycine site on the NMDA receptor. Finally, three NR1 mutants which have been previously shown by others to possess either decreased Mg2+ sensitivity and Ca2+ permeability (N616Q and N616R) or reduced current amplitude (F609L) were tested for their ethanol sensitivity when expressed in combination with the NR2A subunit. Substitution of the wild-type NR1 with F609L did not alter the sensitivity of the receptor to ethanol. However NR1(N616Q)/NR2A and NR1 (N616R)/NR2A injected oocytes showed a reduced sensitivity to ethanol suggesting that alterations in the ion permeation characteristics of recombinant NMDA receptors may influence their sensitivity to ethanol.