Alteration of [3H]MK-801 binding associated with the N-methyl-D-Aspartate receptor complex by acute ethanol in rat cortex and hippocampus in vitro.
Alteration of [3H]MK-801 binding associated with the N-methyl-D-Aspartate receptor complex by acute ethanol in rat cortex and hippocampus in vitro.
复制标题
体外大鼠皮层和海马中急性乙醇改变 [3H]MK-801 与 N-甲基-D-天冬氨酸受体复合物的结合。
DOI：
10.1111/j.1530-0277.1995.tb01507.x
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发表时间：
1995
期刊：
影响因子：
--
通讯作者：
Leslie,SW
中科院分区：
文献类型：
--
作者：
Spuhler-Phillips,K;Gonzalez,J;Randall,PK;Leslie,SW
我们研究了乙醇对[3 H]MK-801与通道内苯环己哌啶（PCP）受体位点特异性结合的影响，作为N-甲基-d-天冬氨酸（NMDA）相关离子通道功能反应变化的指标。对成年大鼠皮层和海马的突触膜匀浆进行饱和结合实验。在基础、10 μm谷氨酸或10 μm谷氨酸+ 30 μ m丝氨酸（含和不含50或100 mm乙醇）条件下进行[3 H]MK-801结合试验。在0或10 μ m谷氨酸盐、不同浓度甘氨酸（0.01、0.10和10 μm）（含和不含100 m甲醇）条件下，进行[3 H]MK-801结合（5 nm）的缔合实验。乙醇（50和100 mm）显著降低了高亲和力（开放通道状态）MK-801受体的百分比，同时降低了低亲和力受体的百分比，但未改变两种结合状态的高亲和力和低亲和力常数。饱和实验表明，在基础和活化条件下，乙醇诱导的闭合通道受体密度增加。缔合实验进一步解释了这一发现，因为乙醇（100 mm）在仅甘氨酸（0.01-10 μm）条件下和谷氨酸+甘氨酸（0.01-0.10 μ m）活化条件下显著降低了快速组分（开放通道）[3 H]MK-801结合。然而，观察到的[3 H]MK-801结合的快和慢动力学速率常数以及总特异性结合（快+慢组分）没有改变。因此，乙醇似乎是NMDA偶联离子通道门控机制和配体进入的非竞争性拮抗剂。这些发现支持先前在电生理学研究中观察到的乙醇选择性减少NMDA激活的钙内流，并减少离子通道开放的频率和持续时间。与先前关于NMDA刺激的钙内流和[3 H]MK-801结合的报告相似，发现在存在10 μ m谷氨酸的情况下，甘氨酸（最大浓度为10 μm）可逆转乙醇对快速组分结合的抑制。
We investigated the effect of ethanol on specific binding of [3H]MK‐801 to the intrachannel phencyclidine (PCP) receptor site, as an index of change in the functional response of theN‐methyl‐d‐Aspartate (NMDA)‐associated ion channel. Saturation binding experiments were performed on synaptic membrane homogenates from adult rat cortex and hippocampus. [3H]MK‐801 binding assays were conducted under conditions of basal, 10 μm glutamate, or 10 μm glutamate + 30 μmd‐serine, with and without 50 or 100 mm ethanol. Association experiments of [3H]MK‐801 binding (5 nm) were conducted under conditions of 0 or 10 μmglutamate, with varying concentrations of glycine (0.01, 0.10, and 10 μm) with and without 100 mmethanol. Ethanol (50 and 100 mm) significantly decreased the percentage of high‐affinity (open‐channel state) MK‐801 receptors with a concomitant increase in percentage of low‐affinity receptors, but did not change high‐ and low‐affinity constants of the two binding states. An ethanol‐induced increase in the closed‐channel receptor density in basal and activated conditions was suggested by the saturation experiments. Association experiments further explained this finding, in that ethanol (100 mm) significantly decreased fast component (open‐channel) [3H]MK‐801 binding in conditions of glycine (0.01–10 μm) only and activated conditions of glutamate + glycine (0.01–0.10 μm). However, the observed fast and slow kinetic rate constants of [3H]MK‐801 binding, as well as total specific binding (fast + slow components), were not altered. Thus, ethanol seems to act as a noncompetitive antagonist upon the gating mechanism of, and ligand access to, the NMDA‐coupled ion channel. These findings support previous observations of ethanol selectively reducing NMDA‐activated calcium influx, and reducing the frequency and duration of ion channel opening in electrophysiological studies. Similar to previous reports on NMDA‐stimulated calcium influx and [3H]MK‐801 binding, glycine (at the maximal concentration of 10 μm), in the presence of 10 μmglutamate, was found to reverse ethanol inhibition of fast component binding.