Regulation of spinal NK1R expression by chronic stress

描述（由申请人提供）：越来越多的证据支持持续压力与肠易激综合征症状的发作或恶化之间的相关性。一些研究表明，强烈的应激与内脏敏感性的持续改变之间存在相关性。更好地了解应激可导致持续内脏痛觉过敏的机制可能对功能性肠病的治疗方法具有重要意义。我们之前的研究表明，大鼠的慢性心理应激导致内脏伤害感觉的持续增加，这涉及脊髓中NK1受体（NK1R）的激活。目前的建议是基于一般的假设，即在该模型中观察到的NK1Rs的脊髓上调是由外周免疫激活和通过初级传入纤维、脊髓小胶质细胞和下行脊髓通路增加的脊髓背角（DH）神经元信号的相互作用介导的。我们将重点关注来自初级传入纤维的信号分子在脊柱DH神经元中调控NK1R基因表达的作用。我们将结合实时定量PCR、免疫组织化学、电泳迁移量测定、Western blot和体内药理学方法来确定参与这种调节的介质。在目的1中，我们将评估应激诱导的结肠免疫激活、原代传入纤维刺激和随后DH神经元中nk1表达增加之间的时间过程相关性。在目标2中，我们将探讨应激诱导的脊髓NK1R上调与同一神经元中转录因子CREB和NFkappaB激活之间的潜在相关性。在目标3中，我们将通过药物治疗评估初级传入神经元在应激诱导的CREB和NFkappaB激活以及NK1R表达增加中的功能贡献。CGRP和脊髓TNFalpha在这种调节作用中的具体作用将被评估。这一建议有望为应激影响内脏伤害感觉加工的机制提供新的见解。

DESCRIPTION (provided by applicant): Converging evidence supports a correlation between sustained stress and the onset or exacerbation of symptoms for Irritable Bowel Syndrome. Some studies indicate a correlation between intense stress and persistent alteration of visceral sensitivity. A better understanding of the mechanisms by which stress can lead to sustained visceral hyperalgesia may have important implications for therapeutic approach of functional bowel disorders. We previously showed that chronic psychological stress in rat leads to sustained increase of visceral nociception that involves NK1 receptors (NK1R) activation in the spinal cord. The current proposal is based on the general hypothesis that spinal up-regulation of NK1Rs observed in this model is mediated by the interplay of peripheral immune activation and increased signaling to spinal dorsal horn (DH) neurons via primary afferent fibers, spinal microglia and descending spinal pathways. We will focus on the role of signaling molecules derived from primary afferent fibers in the regulation of NK1R gene expression in spinal DH neurons. We will use a combination of quantitative real time PCR, immunohistochemistry, electrophoretic mobility shift assay, Western blot and in vivo pharmacological approach to identify the mediators involved in this regulation. In aim 1, we will evaluate the time course correlation between stress-induced colonic immune activation, primary afferent fibers stimulation and subsequent increase of NK1Rexpression in DH neurons. In aim 2, we will address the potential correlation between stress-induced up-regulation of spinal NK1R and activation of the transcription factors CREB and NFkappaB in the same neurons. In aim 3, we will evaluate, through pharmacological treatment, the functional contribution of primary afferent neurons in stress-induced activation of CREB and NFkappaB, and increased expression of NK1R. The specific role of CGRP and spinal TNFalpha in this modulatory effect will be assessed. This proposal is expected to provide new insights into the mechanisms by which stress affects the processing of visceral nociception.