The Role of the Central Amygdala and BST in Stress

描述(由申请者提供)：大量证据表明，心理压力会导致或加剧许多疾病，包括精神疾病。一个被认为对应对压力、恐惧和焦虑非常重要的大脑系统是中央延伸的杏仁核。这一建议是基于这样的假设，即了解杏仁核的主要输出核(中央核，CEA)和相关的大脑区域-终纹床核(BST)如何对心理应激做出正常反应，最终将有助于我们理解一些受应激影响的疾病的病因。由于CEA在恐惧和焦虑行为中的作用已被证明，因此先前已有大量研究针对CEA的激活进行了研究。然而，最近的研究表明，暴露在新奇、噪音或束缚等心理应激环境中，苯丙胺诱导的BST椭圆形核(BSTov)和CEA外侧区(CEAI)内含Enkaphalin神经元的c-fos基因表达下降(~50%)，表明心理应激实际上抑制了这些脑区。潜在地，抑制这些神经元，这些神经元也是GABA能的，将导致它们的传出靶点的去抑制。这些靶点包括BST的梭形核、臂旁外侧核和内侧CEA，它们共同调节几个因应激和焦虑而改变的自主神经、内分泌和行为反应。本申请中描述的实验旨在进一步表征心理应激对BSTov和CEA的影响。在目标1中，将通过半定量原位杂交来评估BSTov和CEA中作为心理应激直接结果的基因表达的潜在变化(即时早期基因、脑啡肽、CRH、P物质或谷氨酸脱羧酶65和67)。这些变化可以在随后的实验中作为一种替代的独立衡量标准。此外，还将确定BSTov和CEAI的应激抑制是否概括为条件应激和非条件应激，以及这些区域的促肾上腺皮质激素释放激素(CRH)和含脑啡肽的细胞。Aim 2中的实验旨在评估心理应激对BSTov和CEA的影响所涉及的神经回路。结合逆行和顺行追踪、双重免疫组织化学、神经化学损伤和谷氨酸注射，将确定是否至少有一个大脑区域既投射到CEAI又投射到BSTov，该区域被应激激活，并且对于应激诱导的这些脑区的基因表达变化是必要和充分的。GABA(γ-氨基丁酸)在这些应激诱导的改变中的潜在作用也将通过以下方法来评估：BSTov和CEAI的GABA能输入的测定，应激期间GABA的活体微透析，以及在应激暴露前向BSTov和CEA脑内注射GABAA和GABAC受体拮抗剂。最终，人们希望，在暴露于压力后正常参与的基本神经回路的知识可能有助于识别一些精神障碍的病因学中涉及的一些神经过程。

DESCRIPTION (provided by applicant): A wealth of evidence has suggested that psychological stress can precipitate or exacerbate many medical conditions, including psychiatric illnesses. One brain system that is thought to be very important for responses to stress, fear and anxiety is the central extended amygdala. This proposal is based on the assumption that knowledge of how a major output nucleus of the amygdala (the central nucleus, CEA) and a related brain region, the bed nucleus of the stria terminalis (BST) normally responds to psychological stress will ultimately help us to understand the etiology of some disorders influenced by stress. Because of the demonstrated role in fear and anxiety behaviors, a significant effort has previously been directed at demonstrating activation of the CEA. However, it has recently been shown that exposure to the psychological stress of novelty, loud noise or restraint results in a decrease (~50 percent) in amphetamine-induced c-fos mRNA expression in enkaphalin-containing neurons of the oval nucleus of the BST (BSTov) and lateral division of the CEA (CEAI), suggesting that psychological stress in fact inhibits these brain regions. Potentially, inhibition of these neurons, that are also GABAergic, would result in disinhibition of their efferent targets. These targets include the fusiform nucleus of the BST, the lateral parabrachial nucleus, and the medial CEA that collectively regulate several autonomic, endocrine, and behavioral responses that are altered by stress and anxiety. The experiments described in this application are designed to further characterize the effects of psychological stress on the BSTov and CEA. In Aim 1, potential changes in gene expression (immediate early genes, enkephalin, CRH, substance P or glutamic acid decarboxylase 65 and 67) that occur in the BSTov and CEA as a direct result of exposure to psychological stress will be assessed by semi-quantitative in situ hybridization. These changes could be used as an alternative independent measure in subsequent experiments. In addition, it will be determined if stress inhibition of the BSTov and CEAI generalizes to conditioned versus unconditioned stress and to corticotropin releasing hormone- (CRH) versus enkephalin-containing cells in these regions. Experiments in Aim 2 are designed to assess the neural circuitry involved in psychological stress effects on the BSTov and CEA. A combination of retrograde and anterograde tracing, dual immunohistochemistry, neurochemical lesions and glutamate injections will be used to determine if there is at least one brain region that projects to both the CEAI and the BSTov, that is activated by stress, and that is necessary and sufficient for the stress-induced gene expression changes in these brain regions. The potential role of GABA (y-amino butyric acid) in these stress-induced changes will also be assessed by determination of GABAergic inputs to the BSTov and CEAI, in vivo microdialysis for GABA during stress, and intracranial injection of GABAA and GABAC receptor antagonists into the BSTov and CEA prior to stress exposure. Ultimately, it is hoped that knowledge of the basic neural circuitry normally engaged following exposure to stress might help to identify some of the neural processes involved in the etiology of some psychiatric disorders.