EXCITOTOXIC MECHANISMS OF ETOH--NMDA RECEPTOR FUNCTION

描述：几个独立实验室使用不同的证据 实验方法表明，急性乙醇选择性地抑制 N-甲基-D-天冬氨酸受体(NR)的药理作用 浓度，而慢性乙醇会产生NR超敏反应，在 至少在一定程度上，与受体上调有关。其结果是，过度 戒酒过程中NRs的激活被认为是导致 相关的癫痫发作、自主神经不稳定和神经毒性。药理学 由于全身性的原因，使用可用的NR拮抗剂治疗是不可取的 抑制这些无处不在的受体。然而，NR在功能上是 由于亚基组成和相关信号的差异而产生的多样性 转导系统。这种多样性可能是选择性效应的原因。 乙醇对不同脑区和不同神经元NRs的影响 特定地区内的人口。通过对其机理基础的探讨 对于这种区域选择性，应该可以设计和利用 在酗酒患者中，有更多的选择性拮抗剂 脆弱的神经细胞群体。为了进一步确定国家安全委员会在 慢性乙醇诱导的海马神经毒性，如下 假说将在成年大鼠身上进行测试：(I)特定水平的增加 将在海马亚区观察到NR亚单位，可能还有mRNAs (CA1，CA3，DG)，与配对喂养的对照组大鼠相比， 以一种与酒精依赖发展相对应的方式。 此外，NR亚基水平的增加将与 II型钙/钙调素依赖性蛋白表达或活性增加 兴奋性与NRS共定位的蛋白激酶(CaM KII) 突触，并与其他形式的兴奋毒性有关；(Ii) 慢性酒精摄入会使CA1、CA3和DG不同程度地敏感 与配对喂养对照相比，神经元对NR介导的兴奋性毒性的影响 可逆方式。这一效应将由Cam Kii介导。为了测试这些 假设，酒精将被给予大鼠1-12周，在某些情况下 在这种情况下，将包括提款期。在ai-m1区，海马区 从酒精处理的大鼠和对照大鼠将使用NRI，NR2和 CaM KII免疫印迹和RT-PCR检测。在Aim 2中，海马片将 比较谷氨酸易感性的地区差异-或 NMDA介导的兴奋性毒性损伤联合“活体-死亡”实验 进行共聚焦成像分析。

DESCRIPTION: Evidence from several independent laboratories using different experimental approaches indicates that acute ethanol selectively inhibits N-methyl-D-aspartate receptor (NR) function at pharmacologically relevant concentrations, whereas chronic ethanol produces NR supersensitivity due, at least in part, to receptor upregulation. As a consequence, excessive activation of NRs during alcohol withdrawal is thought to contribute to the associated seizures, autonomic instability and neurotoxicity. Pharmacologic treatment with available NR antagonists is undesirable due to generalized inhibition of these ubiquitous receptors. However, NRs are functionally diverse due to differences in subunit composition and associated signal transduction systems. This diversity may account for the selective effects of ethanol on NRs in different brain regions, and in different neuronal populations within a particular region. By exploring the mechanistic basis for this regional selectivity, it should be possible to design and utilize in the alcoholic patient more selective antagonists that are targeted to vulnerable neuronal populations. To further define the role of NRs in chronic ethanol-induced neurotoxicity in hippocampus, the following hypotheses will be tested in adult rats: (I) increased levels of specific NR subunits, and possibly mRNAs, will be observed in hippocampal subfields (CA1, CA3, DG) of ethanol-treated rats, relative to pair-fed control rats, in a manner that corresponds to development of ethanol dependence. Moreover, increased levels of NR subunits will be positively correlated with increased expression or activity of a type II Ca2+/calmodulin-dependent protein kinase (CaM KII) that is co-localized with NRs at excitatory synapses and has been implicated in other forms of excitotoxicity; (ii) chronic ethanol ingestion will differentially sensitize CA1, CA3 and DG neurons to NR-mediated excitotoxicity, relative to pair-fed controls, in a reversible manner. This effect will be mediated by CaM KII. To test these hypotheses, ethanol will be administered to rats for 1-12 weeks and, in some cases, will include a withdrawal period. In ai-m 1, hippocampal subfields from ethanol-treated and control rats will be compared using NRI, NR2 and CaM KII immunoblotting and RT-PCR assays. In aim 2, hippocampal slices will be compared for regional differences in vulnerability to glutamate- or NMDA-mediated excitotoxic damage using a "live-dead" assay in conjunction with confocal imaging analysis.