Molecular Regulation of GABA(A) Receptor Function in Amygdala

杏仁核 GABA(A) 受体功能的分子调控

• 批准号: 7141576
• 负责人: Kerry J Ressler
• 金额: $ 37.09万
• 依托单位: EMORY UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-09-01 至 2011-08-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7141576
• 关键词: amygdala; anxiety; benzodiazepines; conditioning; fear; receptor; role; stress

DESCRIPTION (provided by applicant): Comorbid anxiety may predispose addicts to relapse secondary to the biological effects of stress and anxiety on the brain. Furthermore 'hyperexcitability' of the amygdala, as repeatedly seen during stress or fear and substance withdrawal, may contribute to anxiety responses and drug craving. Such increased excitability within the basolateral amygdala (BLA) may be due in part to decreased GABAA activation following stress or substance use. These studies will examine the molecular mechanisms of activity- dependent regulation of GABAA receptors by focusing on fear conditioning and benzodiazepine (BZD) dependence. Both of these manipulations lead to downregulation of GABAA receptors in the BLA. We will compare the molecular mechanisms of GABAA regulation following the stress of fear conditioning with acute, chronic, and withdrawal phases of BZD administration. We hypothesize that: 1) activity-dependent modulation of GABAA within the basolateral amygdala is a common mechanism of both substance dependence and stress response; and 2) GABAergic manipulations that affect BZD response will also affect acquisition and expression of conditioned fear. In this proposal, we will compare the molecular, behavioral, and electrophysiological mechanisms of GABAA regulation following conditioned fear stress with acute, chronic, and withdrawal phases of benzodiazepine administration. We propose that these pharmacological and behavioral events share similar mechanisms involving activity-dependent downregulation of the GABAA complex. A variety of molecular genetic approaches in mice will be used to test this hypothesis including: 1) examination of GABAA complex genes and proteins with in situ hybridization and immunoblotting; 2) manipulation of GABAA receptor expression via amygdala-specific deletion of the GABAA alpha1 gene using the Cre/lox system; 3) manipulation of post-synaptic GABAA alpha2 gene using Lentiviral-mediated gene silencing; 4) manipulation of receptor clustering through silencing of the Gephyrin gene. These studies have direct implications for mechanisms of benzodiazepine dependence, withdrawal, and relapse. Given the role of amygdala GABAergic systems in modulating dopaminergic tone within the nucleus accumbens, amygdala GABAA regulation may have a more general role in addictive disorders. In fact, recent studies have suggested that morphine, alcohol, cocaine and nicotine may also alter GABAA functioning in amygdala, and acutely enhancing GABA levels blocks reinstatement by drug-associated cues or self-administration. This proposal represents a novel approach to understanding shared molecular and cellular mechanisms that may mediate comorbid anxiety and substance abuse disorders. Understanding the mechanisms shared by stress and drug response is critical for understanding pathophysiology and proposing new treatments for these highly comorbid disorders.

描述（由申请人提供）：合并症焦虑可能会倾向于瘾君子，是压力和焦虑对大脑的生物学作用继发的复发。此外，杏仁核的“过度兴奋性”，正如在压力，恐惧和戒断期间反复看到的那样，可能会导致焦虑反应和渴望。这种基底外侧杏仁核（BLA）内的兴奋性增加可能部分归因于压力或药物使用后的GABAA激活降低。这些研究将通过专注于恐惧调节和苯二氮卓（BZD）依赖性来检查GABAA受体的活性依赖性调节的分子机制。这两种操作都导致BLA中GABAA受体的下调。我们将在BZD给药的急性，慢性和戒断阶段进行恐惧调节的压力后，比较GABAA调节的分子机制。我们假设：1）基底外侧杏仁核内GABAA的活性依赖性调节是物质依赖和应激反应的常见机制； 2）影响BZD反应的GABA能操作也会影响条件恐惧的获取和表达。在此提案中，我们将比较加巴调节的分子，行为和电生理机制，随着条件恐惧应激与苯二氮卓类药物的急性，慢性和戒断阶段。我们建议这些药理学和行为事件具有相似的机制，涉及GABAA复合物的活动依赖性下调。小鼠中的多种分子遗传方法将用于检验该假设，包括：1）与原位杂交和免疫印迹一起检查GABAA复杂基因和蛋白质； 2）通过使用CRE/LOX系统对GABAA Alpha1基因的杏仁核特异性缺失操纵GABAA受体表达； 3）使用慢病毒介导的基因沉默来操纵后突触后GABAAα2基因； 4）通过沉默的Gephyrin基因来操纵受体聚类。这些研究对苯二氮卓依赖，戒断和复发的机制有直接的影响。鉴于杏仁核GABA能系统在调节伏伏核中多巴胺能张力中的作用，杏仁核GABAA调节可能在成瘾性疾病中具有更一般的作用。实际上，最近的研究表明，吗啡，酒精，可卡因和尼古丁也可能改变杏仁核中的GABAA功能，并且急性增强的GABA水平会通过药物相关的提示或自我管理来阻止恢复原状。该提案代表了一种新的方法，用于理解共享的分子和细胞机制，可以介导合并焦虑和药物滥用障碍。了解压力和药物反应所共有的机制对于理解病理生理学并为这些高度合并症提出新的治疗方法至关重要。