Stress-Induced Activation of Colonic Motor Function

摘要肠易激综合征（IBS）是一种应激敏感性疾病，腹痛是其主要症状，比其他运动症状更严重。早期生活事件和女性性别是大多数IBS患者发病和症状加重的危险因素。在躯体疼痛领域，有大量的文献将这种现象称为“应激性镇痛”。这与缺乏应激性内脏镇痛（SIVA）的实验数据和知识形成鲜明对比，其中有越来越多的证据表明IBS患者已经损害了这种与应激相关的抑制性降痛调节的参与。我们已经验证了一种新的非侵入性技术来监测啮齿动物的内脏疼痛，并发现心理应激源在雌性部分依赖阿片类药物而雄性不依赖阿片类药物的幼稚啮齿动物中诱发SIVA。我们还获得了初步数据，揭示了结肠中局部crf - propropiomelanocortin (POMC)- β -内啡肽系统受应激上调的影响。基于这些新发现，本研究的总体目标是揭示SIVA在大脑和结肠中的神经化学和分子生理机制，并验证以新生儿母亲反复分离（MS）形式出现的早期生活事件会损害成年期SIVA反应的假设。这将通过针对具体途径的三个目标来实现。AIM 1将描述成年雄性和雌性大鼠的SIVA，在我们的重复避水应激模型中，幼稚和暴露于MS，描述SIVA在大脑和脊髓中的神经元底物。安全系数?表达作为适应性变化的长期标记，通过双标记来识别激活神经元的化学编码，并描绘受体亚型和配体介导纳洛酮依赖成分SIVA。AIM 2将描述应激反应的关键组成部分，脑促肾上腺皮质激素释放因子（CRF）和催产素信号通路的作用。AIM 3，我们将在结肠中揭示功能性crf -POMC衍生肽与垂体的同源系统，其在应激条件下的调节，以及其在心理条件下作为内脏疼痛的潜在调节剂的功能（AIM 1）与局部免疫应激源相比，使用iRNA沉默结肠中的POMC。这些目标将通过药理学、神经解剖学、分子和遗传学方法来实现，这些方法针对阿片类药物、CRF和催产素信号通路，并在大鼠和基因靶向小鼠中进行功能研究。对慢性应激（MS）模型中SIVA的神经元基质和生化编码及其改变的全面了解，对于促进对SIVA生理机制的理解至关重要。在躯体疼痛领域建立的SIVA机制的性别差异的证明将强调性别特异性干预对调节内脏疼痛的重要性，这可能对IBS女性患者具有治疗意义。

DESCRIPTION (provided by applicant): Abstract Irritable bowel syndrome (IBS) is a stress-sensitive disorder for which abdominal pain is a cardinal symptom that drives illness severity more than other motor symptoms. Early life events and female sex are risk factors for the onset and symptom exacerbation of IBS in most patients. In the somatic pain field, there is vast literature on the phenomenon named "stress-induced analgesia". This contrasts with the paucity of experimental data and knowledge on stress-induced visceral analgesia (SIVA), where there is mounting evidence that IBS patients have compromised engagement of this stress-related inhibitory descending pain modulation. We have validated a novel non-invasive technique to monitor visceral pain in rodents and uncovered that psychological stressors induces SIVA in naive rodents which is partly opiate dependent in female and opiate-independent in male rats. We also obtained preliminary data that uncovered in the colon a local CRF-proopiomelanocortin (POMC)-beta-endorphin system that is subject to upregulation by stress. Based on these novel findings, the overall objective of the proposal is to unravel the neurochemical and molecular physiological mechanisms in the brain and the colon underlying SIVA and to test the hypothesis that an early life event in the form of repeated neonatal maternal separation (MS) impairs SIVA response in adulthood. This will be achieved in three aims targeting specific pathways. AIM 1 will characterize SIVA in adult male and female rats, naive and exposed to MS in our model of repeated water avoidance stress, delineate the neuronal substrates of SIVA in the brain and spinal cord using ?Fos? expression as long-term markers of adaptive changes with double labeling to identify chemical coding of activated neurons, and delineate the receptor subtypes and ligand mediating the naloxone-dependent component SIVA in female rats. AIM 2 will delineate the role of key components of the stress response, the brain corticotropin releasing factor (CRF) and oxytocin signaling pathways. AIM 3 we will unravel in the colon the functional CRF-POMC-derived peptides homolog system to the pituitary, its regulation under stress conditions, and its functionality as potential modulator of visceral pain under conditions of psychological (aim 1) vs. local immune stressors using iRNA silencing of POMC in the colon. These aims will be achieved using pharmacological, neuroanatomical, molecular, and genetic approaches targeting the opiate, CRF and oxytocin signaling pathways along with functional studies in rats and genetically targeted mice. Overall advances in the understanding of neuronal substrata and biochemical coding of SIVA and their alterations in a model of chronic stress (MS) is of prime importance to advance understanding of physiological mechanisms underpinning SIVA. The demonstration of sex-differences in these mechanisms underlying SIVA as established in somatic pain field will highlight the importance of sex- specific interventions to modulate visceral pain that may have therapeutic significance in IBS woman patients.