乙醛在酒精性NMDA受体功能变化中的作用及机制的研究

“Prodrug” theory proposes that the effects of alcohol actions in the central nervous system are mainly mediated by alcohol metabolite—acetaldehyde. But, studies using electrophysiological patch clamp shows that NMDA receptor is one of important targets of alcohol action. However, the ongoing clinical treatment for alcohol-induced neurological and psychiatric disorders does not appear to have satisfactory effect by purely affecting the metabolism of acetaldehyde or purely regulating the function of the NMDA receptor. Our recent studies have found corresponding residues in the GluN2A and GluN2B subunits of the NMDA receptor have shown different effect on regulation of ethanol sensitivity and the NMDA receptor function. Also, acetaldehyde may influence the function of the NMDA receptor subtypes. In light of these findings, we will use brain slice cultures, western blot, metabolic enzyme inhibitors,phosphorylation inhibitors and electrophysiological patch clamp techniques et.al., to focus on investigating the interactions between acetaldehyde and ethanol in functional change of the NMDA receptor subtypes. This proposed studies would systematically illustrate the relationship among acetaldehyde, alcohol, and the NMDA receptor.   Therefore, it will clarify the feasibility of the development of a novel pharmacotherapies molecular target between acetaldehyde and the NMDA receptor for the specific treatment of alcohol-induced neurological and psychiatric disorders.   Based on the information obtained from these studies, it is further expected to provide evidence to break through the limitations of current clinical treatment for alcohol abuse and alcoholism by purely affecting the metabolism of acetaldehyde or purely regulating the function of the NMDA receptor.

“前药”理论认为酒精在中枢神经系统的作用主要是由其代谢产物乙醛介导；但电生理膜 片钳研究显示中枢NMDA受体是酒精直接作用的一个重要靶点。目前临床上单纯通过影响乙醛的代谢或者单纯调控NMDA受体功能治疗酒精性神经精神疾病的效果均不理想。申请人近期研究发现：NMDA受体GluN2A、GluN2B亚单位上的等位点残基对酒精的敏感性及功能调节亦不相同，而且乙醛可能影响NMDA受体亚型的功能变化。基于此，本项目拟通过神经元、免疫印迹、代谢酶抑制剂、磷酸酶抑制剂、电生理膜片钳等方法，重点研究乙醛和酒精在NMDA受体亚型功能变化中的相互作用，系统阐明乙醛、酒精、NMDA受体三者之间的关系。明确在乙醛和NMDA受体两者之间探寻开发一种新的特异性的治疗酒精性神经精神疾病的药物分子靶点的可行性，为有望突破目前临床上单纯通过影响乙醛的代谢或者单纯通过调控NMDA受体功能而存在的治疗上的局限性提供理论依据。

“前药”理论认为酒精在中枢神经系统的作用主要是由其代谢产物乙醛介导；但电生理膜片钳研究显示NMDA受体是酒精直接作用的一个重要靶点。NNDA受体不仅存在于中枢神经系统，而且也在外周表达；NMDA受体拮抗剂可有效延缓或防止急性肝衰竭；肝脏作为酒精代谢的主要器官，其NMDA受体亚单位的表达有可能作为肝癌前病变的新生物标志物。FDA批准的戒酒硫是通过抑制乙醛脱氢酶（ALDH）的活性，使乙醛在体内聚集，通过其毒性作用使患者产生焦虑恶心等厌恶反射而达到治疗目的，存在严重毒副作用；批准的阿坎酸尚缺乏一致的临床治疗结果且疗效有限；探寻开发新的治疗酒精性相关疾病的有效药物仍是药理学界的一个方向和难点，而涉及的酒精代谢、乙醛对NMDA受体亚型表达影响以及KD的作用和相关机制的研究是本课题重点。通过动物实验、细胞培养、免疫印迹、蛋白组学、共聚焦等方法，发现：1.乙醛影响神经细胞NMDA受体亚单位GluN1表达。2.金线莲中提取的金线莲苷（KD）5-80μM浓度范围对AML12细胞无毒性作用，3.KD抑制ADH活性，但增加ADH1B蛋白表达量，激活ALDH活性，促进体内乙醛清除。4.KD逆转酒精破坏的SOD活性，恢复GSH/GGSG和NAD+/NADH比例，减轻氧化应激，增强机体抗氧化能力。5.KD抑制BIP蛋白表达和eIF2α蛋白的磷酸化，抑制CHOP蛋白表达和JNK蛋白磷酸化，缓解慢性酒精引起的持续内质网应激。6.KD缓解酒精引起的炎症和凋亡。7.KD通过激活AMPK信号通路，激活被酒精抑制的自噬，减轻细胞损伤。结果显示：乙醛影响NMDA受体亚单位表达，而KD不同于戒酒硫，可增加乙醛脱氢酶的活性，加快乙醛向无毒乙酸的转化，具较好的临床开发潜力，可用于预防和治疗酒精性疾病潜在药物，相关机制的系列研究为将KD推向临床用于治疗酒精性相关疾病提供了一定的理论依据。

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