Activation of CRH Neurons by the Neuropeptide PACAP

神经内分泌、自主神经和行为反应的基本方面由下丘脑室旁核(PVN)中的小细胞促肾上腺皮质激素释放激素(CRH)神经元整合。本实验的主要目的是阐明神经肽垂体腺苷环化酶激活多肽(PACAP)在小细胞CRH神经元中枢激活中的作用，并将PACAP能机制整合到辅助应激反应的特定神经解剖通路中。根据我们的初步数据，我们假设PACAP是微小细胞CRH神经元的内源性激活剂，其作用是由含有PACAP的神经支配所发挥的，参与了通过磷酸化激活转录因子CREB的细胞内信号通路。目的1采用体内药理学方法，结合PVN内局部微量注射，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应用选择性PACAP受体拮抗剂向PVN内微量注射PACAP受体拮抗剂，探讨PVN内源性PACAP在全身和心理应激后激活CRH神经元中的意义。Aim 4将直接测试PACAP神经元是否被应激激活的假设，该脑区是向PVN发送神经支配的脑区。从拟议的实验中综合信息可能会变得适用于更好地理解某些应激相关疾病的病理生理学。

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.