Institute of Psychopharmacology, Central Institute of Mental Health, Medical Faculty Mannheim, University of Heidelberg, Square J5, 68159, Mannheim, Germany.
Translational Neuroscience Facility and Department of Physiology, School of Medical Sciences, UNSW Sydney, Sydney, NSW, Australia.
Psychopharmacology (Berl). 2018 Jun;235(6):1821-1833. doi: 10.1007/s00213-018-4908-6. Epub 2018 Apr 26.
The corticotropin-releasing hormone (CRH) system is a key mediator of stress-induced responses in alcohol-seeking behavior. Recent research has identified the central nucleus of the amygdala (CeA), a brain region involved in the regulation of fear and stress-induced responses that is especially rich in CRH-positive neurons, as a key player in mediating excessive alcohol seeking. However, detailed characterization of the specific influences that local neuronal populations exert in mediating alcohol responses is hampered by current limitations in pharmacological and immunohistochemical tools for targeting CRH receptor subtype 1 (CRHR1).
In this study, we investigated the effect of cell- and region-specific overexpression of CRHR1 in the CeA using a novel transgenic tool.
Co-expression of CRHR1 in calcium-calmodulin-dependent kinase II (αCaMKII) neurons of the amygdala was demonstrated by double immunohistochemistry using a Crhr1-GFP reporter mouse line. A Cre-inducible Crhr1-expressing adeno-associated virus (AAV) was site-specifically injected into the CeA of αCaMKII-Cre transgenic rats to analyze the role of CRHR1 in αCaMKII neurons on alcohol self-administration and reinstatement behavior.
Forty-eight percent of CRHR1-containing cells showed co-expression of αCaMKII in the CeA. AAV-mediated gene transfer in αCaMKII neurons induced a 24-fold increase of Crhr1 mRNA in the CeA which had no effect on locomotor activity, alcohol self-administration, or cue-induced reinstatement. However, rats overexpressing Crhr1 in the CeA increased responding in the stress-induced reinstatement task with yohimbine serving as a pharmacological stressor.
We demonstrate that CRHR1 overexpression in CeA-αCaMKII neurons is sufficient to mediate increased vulnerability to stress-triggered relapse into alcohol seeking.
促肾上腺皮质激素释放激素（CRH）系统是酒精觅药行为中应激反应的关键介质。最近的研究已经确定了杏仁核中央核（CeA），这是一个参与调节恐惧和应激反应的大脑区域，特别富含 CRH 阳性神经元，是介导过度酒精觅药的关键部位。然而，由于目前针对 CRH 受体亚型 1（CRHR1）的药理学和免疫组织化学工具存在局限性，对调节酒精反应的特定神经元群体的具体影响进行详细描述受到了阻碍。
本研究使用新型转基因工具研究 CeA 中 CRHR1 的细胞和区域特异性过表达的影响。
使用 Crhr1-GFP 报告小鼠系通过双重免疫组织化学证明了 CeA 中钙调蛋白依赖性激酶 II（αCaMKII）神经元中的 CRHR1 共表达。Cre 诱导型 Crhr1 表达的腺相关病毒（AAV）被特异性注射到 αCaMKII-Cre 转基因大鼠的 CeA 中，以分析 CRHR1 在 αCaMKII 神经元上对酒精自我给药和复吸行为的作用。
CeA 中 48%的 CRHR1 包含细胞显示与 αCaMKII 的共表达。αCaMKII 神经元中的 AAV 介导的基因转移导致 CeA 中 Crhr1 mRNA 的 24 倍增加，但对运动活性、酒精自我给药或线索诱导的复吸没有影响。然而，在 CeA 中过表达 Crhr1 的大鼠在应激诱导的复吸任务中增加了反应，而育亨宾作为一种药理学应激源。
我们证明了 CeA-αCaMKII 神经元中 CRHR1 的过表达足以介导对应激引发的酒精觅药复发的易感性增加。
