Molecular mechanisms of excessive alcohol consumption and relapse-like behavior

过度饮酒行为和复发的行为和分子机制尚未完全了解，对于绘制酒精中毒/依赖的病理过程至关重要。最近的证据表明，长期饮酒会导致大脑边缘系统关键区域的兴奋性突触加强，这些区域介导奖励和饮酒行为。突触的这种强化高度依赖于α-氨基-3-羟基-5-甲基-4-异恶唑丙酸受体（AMPAR）的作用和突触掺入; AMPAR是由兴奋性神经递质谷氨酸激活的快速作用离子通道受体。然而，增强的AMPAR信号在酒精强化和酒精寻求行为中的机制作用仍不清楚。因此，在本申请中提出的实验试图阐明的行为和分子机制的基础上，AMPAR介导的增加操作性酒精自我管理和增强复发样行为使用临床前模型的高酒精消费，酒精偏好（P-）大鼠。初步数据表明，增强的AMPAR信号预处理与阿尼西坦（正变构调节剂的AMPAR），增加操作性酒精自我管理和增强线索诱导的恢复酒精寻求P-大鼠，这表明增强的AMPAR活性可能是至关重要的，在促进增加饮酒和易感性复发。实验将进一步表征增强的AMPAR信号传导在调节操作性自我给药和复发样行为中的作用。AMPAR活性可通过翻译后修饰（例如AMPAR GluR 1亚基氨基酸残基831的磷酸化; pGluR 1 {831}）增强。使用免疫组织化学技术，实验将映射神经适应性变化的pGluR 1 {831}亚基在边缘脑区的历史后，酒精自我管理或暴露于酒精相关的线索在线索诱导的恢复，以确定大脑区域，可能会影响增强AMPAR介导的增加自我管理和酒精寻求。我们预测在丘脑核（自我给药研究）或杏仁核（恢复研究）中看到pGluR 1 {831}的变化，这些区域将被靶向研究增强的AMPAR活性介导的促进酒精自我给药和使用阿尼西坦寻求行为的功能神经解剖学控制。对照实验将解决神经解剖学和神经特异性和非特异性运动效应。最后，我们将通过在自我给药和使用KN 93（CamKII抑制剂）恢复期间阻断茴香拉西坦诱导的效应，确定茴香拉西坦诱导的酒精自我给药和寻找行为增加是否依赖于Ca 2 +/钙调蛋白依赖性蛋白激酶II（CamKII;已知磷酸化GluR 1并增强AMPAR活性）。这些研究的关键发现将为过量饮酒行为和复发脆弱性的AMPAR相关机制提供新的见解。

The behavioral and molecular mechanisms underlying excessive alcohol drinking behavior and relapse are not fully understood and are vital for mapping the pathological course of alcoholism/dependence. Recent evidence indicates that chronic alcohol consumption leads to strengthening of excitatory synapses in key limbic brain regions that mediate reward and drinking behavior. This strengthening of synapses is highly dependent on the actions and synaptic incorporation of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs); fast action ion channel receptors that are activated by the excitatory neurotransmitter glutamate. However, the mechanistic role of enhanced AMPAR signaling in alcohol reinforcement and alcohol-seeking behavior remains unclear. Thus, the proposed experiments in this application seek to elucidate the behavioral and molecular mechanisms that underlie AMPAR-mediated increases in operant alcohol-self-administration and potentiated relapse-like behavior using a preclinical model of high alcohol consumption, the alcoholpreferring (P-) rat. Preliminary data indicate that enhancement of AMPAR signaling by pretreatment with aniracetam (positive allosteric modulator of AMPARs), increases operant alcohol self-administration and potentiates cue-induced reinstatement to alcohol seeking in P-rats, suggesting that enhanced AMPAR activity may be critical in facilitating increased drinking and susceptibility to relapse. Experiments will further characterize the role of enhanced AMPAR signaling in modulating operant self-administration and relapse-like behavior. AMPAR activity can be potentiated by post-translational modification (e.g. phosphorylation of the AMPAR GluR1 subunit amino acid residue 831;pGluR1{831}). Using immunohistochemistry techniques, experiments will map neuroadaptive changes in pGluR1{831} subunits in limbic brain regions after a history of alcohol self-administration or exposure to an alcohol-related cue during cue-induced reinstatement to determine brain regions that may influence enhanced AMPAR-mediated increases in self-administration and alcohol-seeking. We predict to see changes in pGluR1{831} in the nucleus accumbens (self-administration studies) or amygdala (reinstatement studies), and these regions will be targeted to investigate functional neuroanatomical control of enhanced AMPAR activity-mediated facilitation of alcohol self-administration and seeking behavior using aniracetam. Control experiments will address neuroanatomical and reinforcer specificity and non-specific locomotor effects. Lastly we will determine if aniracetam-induced increases in alcohol self-administration and seeking behavior are dependent on Ca2+/calmodulin-dependent protein kinase II (CamKII; known to phosphorylate GluR1 and enhance AMPAR activity) by blocking aniracetam-induced effects during self administration and reinstatement sessions with KN93 (CamKII inhibitor). Key findings from these studies will provide novel insight into AMPAR-related mechanisms in excessive alcohol drinking behavior and vulnerability to relapse.