Role of clock genes in colonic motility

描述（由申请人提供）：人类在白天有排便，经常在醒来后或饭后，但很少在夜间。与这一观察相一致的是动态压力记录，显示白天最大的结肠活动。因此，结肠运动是有节奏的。我们日常生活节奏的中断，如倒班工作或时区旅行，与胃肠道症状有关。这些观察结果表明，我们的日常节律和胃肠道生理之间存在功能相关性。生物节律由生物钟基因控制。大脑中有一个中央时钟。然而，时钟基因也存在于外周器官中。在外周器官内，时钟基因控制着一组组织特异性基因的表达，从而直接影响生理功能。生物钟基因可以与外部时间线索同步，比如光/暗周期和进食。我们的初步数据显示时钟基因在小鼠结肠中的表达。这种表达是有节奏的，在黑暗周期开始时增加。与此同时，参与合成结肠神经递质乙酰胆碱和一氧化氮的酶在黑暗周期开始时增加。此外，我们发现小鼠在夜间排出的粪便颗粒数量增加。这与夜间结肠内压活动增加有关，通过一种新开发的方法对自由活动小鼠进行长时间的结肠内压监测。我们发现结肠时钟基因在肌丛中表达，肌丛是神经递质合成的重要部位。综上所述，这些数据表明结肠可能具有计时能力，允许结肠运动对环境刺激进行生理适应。我们假设光/暗周期和摄食时间表的变化通过时钟基因影响结肠运动。我们研究的总体目标是确定光/暗周期和摄食时间表的变化对野生型和时钟基因（PER1/PER2）敲除小鼠时钟基因表达、神经递质合成酶表达和结肠运动的影响。在这种程度上，我们将使用激光捕获显微镜，实时PCR和结肠运动研究。这一建议将确定时钟基因是否在结肠运动中发挥作用。这一点很重要，因为胃肠功能障碍是时区旅行者和轮班工作者的常见抱怨。我们推测，这些个体的胃肠道症状是由于生物钟基因无法及时调整环境线索的变化。该项目的长期目标是更好地了解时钟基因在结肠运动中的作用，参与结肠时钟基因携带的途径，它们在运动障碍综合征中的作用，并最终开发药物干预措施，以增强时钟基因与环境变化的同步。

DESCRIPTION (provided by applicant): Humans have bowel movements during the day, frequently following awakening or following a meal but rarely during the night. In line with this observation are ambulatory pressure recordings demonstrating maximal colonic activity during the day. Thus colonic motility follows a rhythm. Disruption of our daily rhythm such as occurs with shift work or time zone traveling, is associated with gastrointestinal symptoms. These observations suggest a functional correlation between our daily rhythm and gastrointestinal physiology. Biological rhythms are controlled by clock genes. A central clock is located in the brain. However, clock genes are present in peripheral organs as well. Within peripheral organs, clock genes control the expression of a subset of tissue-specific genes, thereby directly affecting physiological function. Clock genes can synchronize themselves to external time cues such as the light/dark cycle and feeding. Our preliminary data show expression of clock genes in the murine colon. This expression is rhythmic and increases at the start of the dark cycle. Along with this, enzymes involved in the synthesis of the colonic neurotransmitters acetylcholine and nitric oxide increase at the onset of the dark cycle. Moreover, we show that mice pass an increased number of stool pellets at night. This is associated with increased nocturnal intracolonic pressure activity, as assessed by a newly developed method for prolonged intracolonic pressure monitoring in freely moving mice. We show colonic clock gene expression in the myenteric plexus, an important site of neurotransmitter synthesis. Taken together, the data suggest that the colon may have a time-keeping capability that allows for the physiological adaptation of colonic motility to environmental stimuli. We hypothesize that changes in the light/dark cycle and feeding schedule affect colonic motility through clock genes. The overall goal of our studies are to determine the effect of changes in light/dark cycle and feeding schedule on clock gene expression, neurotransmitter synthesizing enzyme expression and colonic motility in wildtype and clock gene (PER1/PER2) knockout mice. To this extent we will use laser capture microscopy, real-time PCR and colonic motility studies. This proposal will establish whether clock genes play a role in colonic motility. This is important, as gastrointestinal dysfunction is a common complaint of time-zone travelers and shift workers. We speculate that the gastrointestinal symptoms of those individuals result from the inability of clock genes to make timely adjustments to changes in environmental cues. The long-term goal for this project is to develop a better understanding of the role of clock genes in colonic motility, the pathways participating in the entrainment of colonic clock genes, their role in dysmotility syndromes and eventually, the development of pharmacological interventions that will enhance the synchronization of clock genes to changes in the environment.