Cross-talk between the colon epithelium, colon afferents and sympathetic neurons regulate pain in the normal and inflamed colon

结肠上皮、结肠传入神经和交感神经元之间的串扰调节正常和发炎结肠的疼痛

• 批准号: 10617264
• 负责人: Kathryn Marie Albers
• 金额: $ 46.01万
• 依托单位: UNIVERSITY OF PITTSBURGH AT PITTSBURGH
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-05-05 至 2025-04-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10617264
• 关键词: Acute; Afferent Neurons; Biological Assay; Calcium; Calcium Signaling; Chemicals; Chronic; Colon; Colonic inflammation; Communication; Data; Disease; Dissociation; Electric Stimulation; Epithelial Cells; Epithelium; Fiber; Frequencies; Glutamates; Goals; Hypersensitivity; Image; Immune system; Inflammation; Inflammatory Bowel Diseases; Injury; Limb structure; Measures; Mechanical Stimulation; Modeling; Motor Neurons; Mus; Nature; Neuromodulator; Neurons; Neurotransmitter Receptor; Neurotransmitters; Norepinephrine; Occupations; Opsin; Organism; Pain; Pain management; Peripheral; Peripheral Nervous System; Pharmacology; Phase; Phenocopy; Physiological; Preparation; Process; Proton Pump; Serotonin; Signal Transduction; Sodium Dextran Sulfate; Spinal; Spinal Cord; Stimulus; Stress; Stretching; Sympathetic Ganglia; Symptoms; Synapses; System; Testing; Time; Vertebral column; Visceral; Visceral pain; behavioral response; cell type; chronic pain; colorectal distension; dextran sulfate sodium induced colitis; experimental study; neuronal circuitry; neuronal excitability; novel; patch clamp; response; spinal nerve posterior root; spine bone structure

SUMMARY Visceral pain is notoriously difficult to treat, often persisting long after the precipitating injury/disease is no longer evident. In this application we will explore a novel, multicellular peripheral circuit that we hypothesize explains many of the intractable features of chronic, visceral pain. We now know that epithelial-neuronal communication is widespread, with numerous epithelial cell types releasing neuroactive substances (e.g., ATP, ACh, 5HT, glutamate). This is particularly apparent in the colon where we have found that channelrhodopsin (ChR2) -induced activation of colon epithelial cells produces high frequency bursting of colon extrinsic primary afferent neurons (ExPAN’s), phenocopying physiologic stimuli and inducing robust behavioral responses (visceromotor responses (VMR), a validated assay of hypersensitivity). Building on these findings, new surprising data indicate colon epithelium also receives functional input from sympathetic neurons; activation of sympathetic projections to the colon induces large, phase-locked calcium signals in the epithelium. Closing the loop, we found that activation of ExPAN’s via colorectal distension (CRD) induces calcium signals in the post-ganglionic sympathetic neurons projecting to the colon, and that ChR2- induced activation of ExPAN’s induces cFos expression in these same neurons. That this multicellular circuit plays a role in visceral pain is supported further by preliminary data that shows that inflammation (acute and/or chronic) is correlated with increased signaling in all portions of this circuit. Thus, the goal of the proposed experiments is to test the hypothesis that persistent visceral hypersensitivity is due, at least in part, to amplification in an epithelial-ExPAN-sympathetic circuit such that it is possible to treat pain by breaking any limb of this feed-forward circuit (Fig.1). This hypothesis will be tested in 3 aims: Aim 1: Determine if persistent hypersensitivity induced in a model of IBD (DSS (dextran sulfate sodium)) is due to increased epithelial signaling and/or ExPAN excitability, Aim 2: Determine if DSS-induced inflammation increases the ability of ExPANs to activate sympathetic neurons in prevertebral sympathetic ganglion (PrSG) directly (via synapses in PrSG) or indirectly (via a spinal cord circuit) and, Aim 3 Determine the ability of sympathetic neurons to drive activity in epithelial cells in naïve mice and in the DSS model of IBD.

概括 众所周知，内脏疼痛很难治疗，通常在诱发损伤/疾病消失后仍持续很长时间。 更明显。在此应用中，我们将探索一种新颖的多细胞外围电路，我们假设 解释了慢性内脏疼痛的许多棘手特征。 我们现在知道上皮神经元通讯是广泛存在的，有多种上皮细胞类型 释放神经活性物质（例如 ATP、ACh、5HT、谷氨酸）。这在结肠中尤其明显 我们发现视紫红质通道蛋白 (ChR2) 诱导的结肠上皮细胞激活产生高 结肠外源初级传入神经元（ExPAN）的频率爆发，表型生理刺激和 诱导强烈的行为反应（内脏运动反应（VMR），一种经过验证的超敏反应测定）。 基于这些发现，新的令人惊讶的数据表明结肠上皮也接收来自 交感神经元；激活结肠的交感神经投射会产生大量的锁相钙 上皮细胞中的信号。结束循环，我们发现 ExPAN 通过结直肠扩张 (CRD) 激活 在投射到结肠的节后交感神经元中诱导钙信号，并且 ChR2- ExPAN 的诱导激活会诱导这些相同神经元中的 cFos 表达。这个多细胞电路 初步数据进一步支持在内脏疼痛中发挥作用，该数据表明炎症（急性和/或 慢性）与该回路所有部分的信号传导增加相关。 因此，所提出的实验的目的是检验以下假设：持久的内脏 超敏反应至少部分归因于上皮-ExPAN-交感神经回路的放大，例如 可以通过破坏该前馈电路的任何分支来治疗疼痛（图 1）。这个假设 将在 3 个目标中进行测试： 目标 1：确定 IBD 模型（DSS （右旋糖酐硫酸钠））是由于上皮信号传导和/或 ExPAN 兴奋性增加所致，目标 2：确定是否 DSS 诱导的炎症增加了 ExPAN 激活椎前交感神经元的能力 直接（通过 PrSG 中的突触）或间接（通过脊髓回路）连接交感神经节 (PrSG)，目标 3 确定交感神经元驱动初始小鼠和 DSS 中上皮细胞活动的能力 IBD 模型。