Department of Neurosciences, School of Medicine, University of New Mexico, Albuquerque, New Mexico, USA.
Alcohol Clin Exp Res. 2010 Feb;34(2):342-53. doi: 10.1111/j.1530-0277.2009.01096.x. Epub 2009 Nov 24.
Although several reports have been published showing prenatal ethanol exposure is associated with alterations in N-methyl-D-aspartate (NMDA) receptor subunit levels and, in a few cases, subcellular distribution, results of these studies are conflicting.
We used semi-quantitative immunoblotting techniques to analyze NMDA receptor NR1, NR2A, and NR2B subunit levels in the adult mouse hippocampal formation isolated from offspring of dams who consumed moderate amounts of ethanol throughout pregnancy. We employed subcellular fractionation and immunoprecipitation techniques to isolate synaptosomal membrane- and postsynaptic density protein-95 (PSD-95)-associated pools of receptor subunits.
We found that, compared to control animals, fetal alcohol-exposed (FAE) adult mice had: (i) increased synaptosomal membrane NR1 levels with no change in association of this subunit with PSD-95 and no difference in total NR1 expression in tissue homogenates; (ii) decreased NR2A subunit levels in hippocampal homogenates, but no alterations in synaptosomal membrane NR2A levels and no change in NR2A-PSD-95 association; and (iii) no change in tissue homogenate or synaptosomal membrane NR2B levels but a reduction in PSD-95-associated NR2B subunits. No alterations were found in mRNA levels of NMDA receptor subunits suggesting that prenatal alcohol-associated differences in subunit protein levels are the result of differences in post-transcriptional regulation of subunit localization.
Our results demonstrate that prenatal alcohol exposure induces selective changes in NMDA receptor subunit levels in specific subcellular locations in the adult mouse hippocampal formation. Of particular interest is the finding of decreased PSD-95-associated NR2B levels, suggesting that synaptic NR2B-containing NMDA receptor concentrations are reduced in FAE animals. This result is consistent with various biochemical, physiological, and behavioral findings that have been linked with prenatal alcohol exposure.
尽管已有数篇报道表明，产前乙醇暴露与 N-甲基-D-天冬氨酸（NMDA）受体亚单位水平的改变有关，在某些情况下还与亚细胞分布有关，但这些研究的结果存在争议。
我们使用半定量免疫印迹技术分析了从妊娠期间大量摄入乙醇的母鼠后代的成年小鼠海马区中 NMDA 受体 NR1、NR2A 和 NR2B 亚单位的水平。我们采用亚细胞分离和免疫沉淀技术来分离突触体膜和突触后密度蛋白 95（PSD-95）相关的受体亚单位。
与对照组动物相比，胎儿酒精暴露（FAE）的成年小鼠有：（i）突触体膜 NR1 水平升高，而与该亚单位与 PSD-95 的结合无变化，组织匀浆中总 NR1 表达无差异；（ii）海马组织匀浆中 NR2A 亚单位水平降低，但突触体膜 NR2A 水平无变化，NR2A-PSD-95 结合无变化；（iii）组织匀浆或突触体膜 NR2B 水平无变化，但 PSD-95 相关 NR2B 亚单位减少。NMDA 受体亚单位的 mRNA 水平没有改变，这表明产前酒精相关的亚单位蛋白水平差异是亚单位定位的转录后调控差异的结果。
我们的结果表明，产前酒精暴露会导致成年小鼠海马区特定亚细胞位置的 NMDA 受体亚单位水平发生选择性变化。特别值得注意的是 PSD-95 相关 NR2B 亚单位水平降低，这表明 FAE 动物的突触 NR2B 含有 NMDA 受体浓度降低。这一结果与各种与产前酒精暴露相关的生化、生理和行为发现一致。
