Gut Mechanisms of Stress-Induced Comorbid Visceral Pain

项目摘要/摘要 慢性并存疼痛或重叠疼痛状况(COPC)可能从个人和 社会立场。患者--主要是女性--目前有两种或两种以上的慢性疼痛障碍。 COPC的病因知之甚少，但与情绪压力有很强的联系，这是一个促成因素。 在存在神经病理性三叉神经痛(CCI)的雌性大鼠中，3天强迫游泳(FS)。 压力会导致持久的内脏高敏感，指的是下背部。在有这种共病内脏的大鼠身上 疼痛，5-HT3R蛋白在腰椎(L6-S1)脊髓和相应的 背根节(DRG)。一致地，鞘内阻断5-HT3R可瞬时减弱所述 痛觉过敏。这些观察结果表明，5-HT3R介导的初级致敏作用参与了 应激性内脏痛的肠道传入。然而，潜在的肠道机制 人们对此仍然知之甚少。越来越多的最新证据支持肠道微生物的重要性 应激性内脏痛发病机制中的调节失调。但目前尚不清楚应激诱导的肠道 生物失调是内脏痛发生的细胞和分子机制的中介。我们 检测FS应激前后神经病理性三叉神经痛大鼠的粪便微生物区系组成。我们的 初步数据显示，被引用的雌性大鼠肠道微生物组发生了广泛的成分变化 痛觉过敏。此外，CCI FS供体的粪便微生物区系转移(FMT)会引起牵涉性痛觉过敏 持续口腔面部疼痛的CCI接受者。这种治疗对幼稚的接受者没有太大影响， 强调CCI诱导的5-羟色胺能下行易化的重要性。另一方面，FMT来自 天真的供者减轻CCI FS受者的牵涉性痛觉过敏。我们假设CCI FS诱导肠道 肠道初级传入细胞中5-HT3R调节失调的生物失调。这种监管失调 只有在蛋白质水平上才明显，这意味着转录后机制，特别是microRNAs。近期 文献支持肠道微生物区系在调节宿主microRNA表达中的作用。因此，我们进一步 假设在CCI FS大鼠中，肠道生物失调导致5-HT3R靶向microRNAs表达减少 来自肠道的初级传入神经。这导致5-HT3R蛋白表达增加，而不影响其mRNA 级别。我们将使用多学科方法来测试我们的假设，如三个目标中所述。在目标1中，我们 将研究5-HT3R在持续性下腰痛发病机制中的作用。在目标2中，我们将 解决肠道微生物失调在相关下腰痛发展中的作用。在《目标3》中，我们将 研究肠道微生物区系与5-HT3R表达改变的转录后机制。我们的研究 旨在梳理出外周肠道机制和分子基础之间可能的因果关系 合并内脏疼痛的症状。这一奖项将帮助申请者在研究综合体方面建立一个成功的职业生涯。 慢性疼痛障碍的机制及其更复杂的共病。

Project Summary/Abstract Chronic comorbid pain or overlapping pain conditions (COPCs) can be devastating from both personal and societal standpoints. Sufferers – predominantly women – present with two or more chronic pain disorders. Etiology of COPCs is poorly understood but there is a strong link to emotional stress as a contributing factor. We showed that in female rats with existing neuropathic trigeminal pain (CCI), 3-day forced swimming (FS) stress induces lasting visceral hypersensitivity referred to the lower back. In rats with such comorbid visceral pain, 5-HT3R protein expression is upregulated in the lumbosacral (L6-S1) spinal cord and corresponding dorsal root ganglia (DRG). Consistently, intrathecal blockade of 5-HT3R transiently attenuates referred hyperalgesia. These observations suggest the involvement of 5-HT3R-mediated sensitization of primary afferents from the gut in stress-induced comorbid visceral pain. However, the underlying gut mechanisms remain poorly understood. Accumulating recent evidence supports the importance of gut microbial dysregulation in the pathogenesis of stress-induced visceral pain. But it is unclear whether stress-induced gut dysbiosis mediates cellular and molecular mechanisms underlying the development of visceral pain. We examined fecal microbiota composition of rats with neuropathic trigeminal pain before and after FS stress. Our preliminary data show extensive compositional changes in the gut microbiome of female rats with referred hyperalgesia. Furthermore, fecal microbiota transfer (FMT) from CCI+FS donors induces referred hyperalgesia in CCI recipients with ongoing orofacial pain. This treatment does not much affect naïve recipients, which underscores the importance of CCI-induced descending serotonergic facilitation. On the other hand, FMT from naïve donors attenuates referred hyperalgesia in CCI+FS recipients. We hypothesize that CCI+FS induces gut dysbiosis that contributes to dysregulation of 5-HT3R in the primary afferents from the gut. This dysregulation is evident only at the protein level implicating a posttranscriptional mechanism, particularly microRNAs. Recent literature supports the role of gut microbiota in regulating host microRNA expression. Therefore, we further hypothesize that in CCI+FS rats, gut dysbiosis leads to reduced expression of 5-HT3R-targeting microRNAs in primary afferents from the gut. This results in increased 5-HT3R protein expression without affecting its mRNA levels. We will use multidisciplinary approaches to test our hypotheses as described in three aims. In aim 1, we will examine the role of 5-HT3R in the pathogenesis of persistent referred low back pain. In aim 2, we will address the role of gut microbial dysbiosis in the development of referred low back pain. In aim 3, we will investigate gut microbiota-associated posttranscriptional mechanisms of altered 5-HT3R expression. Our study is designed to tease out possible causality between peripheral gut mechanisms and molecular underpinnings of comorbid visceral pain. This award will help the applicant build a successful career in studying complex mechanisms of chronic pain disorders and their ever more complex comorbidities.