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）：由于压力和焦虑对大脑的生物影响，共病焦虑可能会使成瘾者容易复发。此外，在压力或恐惧和物质戒断过程中反复出现的杏仁核“过度兴奋”可能会导致焦虑反应和药物渴望。基底外侧杏仁核 (BLA) 内兴奋性的增加可能部分是由于压力或物质使用后 GABAA 激活减少所致。这些研究将通过关注恐惧调节和苯二氮卓类（BZD）依赖性来研究 GABAA 受体活性依赖性调节的分子机制。这两种操作都会导致 BLA 中 GABAA 受体的下调。我们将比较恐惧调节应激后 GABAA 调节的分子机制与 BZD 给药的急性期、慢性期和戒断期。我们假设：1）基底外侧杏仁核内 GABAA 的活动依赖性调节是物质依赖性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性恐惧的获得和表达。在本提案中，我们将比较条件性恐惧应激后 GABAA 调节的分子、行为和电生理机制与苯二氮卓类药物给药的急性、慢性和戒断阶段。我们认为这些药理学和行为事件具有相似的机制，涉及 GABAA 复合物的活性依赖性下调。将在小鼠中使用多种分子遗传学方法来检验这一假设，包括：1）通过原位杂交和免疫印迹检查 GABAA 复杂基因和蛋白质； 2) 使用 Cre/lox 系统通过杏仁核特异性删除 GABAA α1 基因来操纵 GABAA 受体表达； 3) 使用慢病毒介导的基因沉默操作突触后GABAA α2基因； 4）通过Gephyrin基因的沉默来操纵受体簇。这些研究对苯二氮卓类药物依赖、戒断和复发的机制有直接影响。鉴于杏仁核 GABA 能系统在调节伏隔核内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普遍的作用。事实上，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 GABAA 的功能，并且急剧提高 GABA 水平会阻止药物相关线索或自我给药的恢复。该提案代表了一种了解可能介导共病焦虑和药物滥用障碍的共同分子和细胞机制的新方法。了解压力和药物反应所共有的机制对于了解病理生理学并为这些高度共存疾病提出新的治疗方法至关重要。