Activation of CRH Neurons by the Neuropeptide PACAP

下丘脑室旁核（PVN）的小细胞促肾上腺皮质激素释放激素（CRH）神经元整合了神经内分泌、自主神经和行为对应激的反应。 拟进行的实验的主要目的是阐明神经肽垂体腺苷酸环化酶激活多肽（PACAP）在小细胞CRH神经元的中枢激活中的作用，并将PACAPergic机制整合到特定的神经解剖学通路中，从而使应激反应得以实现。 基于我们的初步数据，我们假设PACAP是小细胞CRH神经元的内源性激活剂，其作用是由含有神经支配的PACAP施加的，并参与通过磷酸化激活转录因子CREB的细胞内信号通路。 目的1：利用PVN内局部注射的体内药理学方法，研究PACAP在CRH神经元转录激活中的作用及其与肾上腺素能机制的相互作用。 目的2将确定内源性PACAP在PVN的CRH神经元的激活的意义，以下系统和心理应激，使用选择性PACAP受体拮抗剂微量注射到PVN。 目的3：通过神经解剖学追踪结合免疫荧光技术，研究PVN中PACAP神经支配对CRH神经元的脑区特异性作用。 目的4将直接检验这一假设，即在向PVN发送神经支配的脑区域中，PACAP神经元是否被应激激活。因此，这些目标的综合结果将揭示急性应激时PACAP对下丘脑-垂体-肾上腺轴中枢神经内分泌效应系统的生理作用。 从拟议的实验信息的合成可能成为适用于更好地理解某些压力相关疾病的病理生理。

Fundamental aspects of the neuroendocrine, autonomic and behavioral responses to stress are integrated by parvocellular corticotropin releasing hormone (CRH) neurons in the hypothalamic paraventricular nucleus (PVN). The main goal of the proposed experiments is to elucidate the role of the neuropeptide pituitary adenylate cyclase-activating polypeptide (PACAP) in the central activation of parvocellular CRH neurons and to integrate the PACAPergic mechanisms into specific neuroanatomical pathways subserving the stress response. Based on our preliminary data, we hypothesize that PACAP is an endogenous activator of parvocellular CRH neurons and its actions are exerted by PACAP containing innervation, with the involvement of intracellular signaling pathways that activate the transcription factor CREB by phosphorylation. Aim 1, using in vivo pharmacologic approaches with local intra-PVN microinjections, will investigate the role of PACAP in transcriptional activation of CRH neurons as well as its interactions with adrenergic mechanisms. Aim 2 will determine the significance of endogenous PACAP in the PVN for the activation of CRH neurons, following systemic and psychological stressors, using selective PACAP receptor antagonist microinjections into the PVN. Aim 3 will identify the brain region-specific contribution of PACAP innervation to CRH neurons in the PVN from neuroanatomical tract-tracing experiments combined with multiple-labeling immunofluorescence. Aim 4 will directly test the hypothesis whether PACAP neurons are activated by stress in brain regions that send innervation to the PVN. Thus, combined results from these aims will reveal the physiological role of PACAP for the central neuroendocrine effector system of the hypothalamic-pituitary-adrenal axis in acute stress. Synthesis of information from the proposed experiments may become applicable toward a better understanding of the pathophysiology of certain stress-related illnesses.