NO-mediated regulation of the pacemaker function and motility in the murine jejunum and colon

NO敏感鸟苷酸环化酶参与许多生理调节过程，如血压调节、突触可塑性或胃肠运动。这种酶被一氧化氮（NO）激活，并催化第二信使cGMP的形成。我们已经产生了NO-GC被全面删除的小鼠。这些小鼠患有胃肠动力障碍、血压升高和过早死亡。GCKO小鼠胃肠道运动能力的降低是由于NO介导的氮能舒张功能的缺乏。氮能舒张的确切机制至今尚未完全阐明。参与介导NO作用的细胞类型的身份仍不清楚，因为NO-GC在平滑肌细胞（SMC）以及Cajal间质细胞（ICC）、成纤维细胞样细胞（FLC）甚至在某些神经元中表达。在ICC中，两种不同的亚型具有不同的功能：肌间ICC（ICC-MY）产生起搏电位，而肌内ICC（ICC-IM）负责肠道神经传递。本研究旨在探讨NO/cGMP对结肠和空肠不同部位起搏系统节律性和自发性收缩的调节作用。我们将使用在整体上缺乏NO-GC或在SMC、ICC或两者中特异性缺乏NO-GC的KO小鼠。将从这些动物中采集空肠和结肠的不同部分，用于器官浴研究（自发收缩）和微电极研究（慢波）。将使用免疫组织化学研究NO-GC和NO/cGMP信号级联的其他成员的表达。此外，将测量这些KO动物的离体空肠和结肠的离体运动性。在所有子项目中，我们将研究通过新型NO-GC激活剂/刺激剂Bay 41-2272或Bay 58-26678（Cinaciguat）激活NO/cGMP系统是否对肠道运动具有治疗潜力。来自鼠组织的数据最终将与从人组织获得的数据相关联。总之，我们的NO-GC KO小鼠将有助于阐明慢波自发收缩是如何相互关联和调节的氮能系统。

NO-sensitive guanylyl cyclase is involved in many physiological regulatory processes such as regulation of blood pressure, synaptic plasticity or gastrointestinal motility. The enzyme is activated by nitric oxide (NO) and catalyzes the formation of the second messenger cGMP. We have generated mice in which NO-GC is deleted globally. These mice suffer from gastrointestinal dysmotility, elevated blood pressure and premature death. However, the cell/tissue types responsible for the individual phenotypes are not yet clear.The reduced GI motility in global GCKO mice is based on the lack of the nitrergic (NO-mediated) relaxation. The exact mechanism of nitrergic relaxation is still not elucidated thoroughly. The identity of the cell types involved in mediating the effect of NO is still unclear as NO-GC is expressed in smooth muscle cells (SMC) as well as interstitial cells of Cajal (ICC), fibroblast-like cells (FLC) and even in certain neurons. Among ICCs, two different subtypes are of special interest with distinct functions: Myenteric ICC (ICC-MY) generate the pacemaker potential whereas intramuscular ICC (ICC-IM) are held responsible of enteric neurotransmission. The effect of neuronally released NO on these two types of ICC is being intensely discussed.In this project, we want to investigate how NO/cGMP regulate rhythmicity of the pacemaker system and spontaneous contractions in different colon and jejunum sections. We will use KO mice lacking NO-GC globally or specifically in SMC, ICC or both. Different parts of jejunum and colon will be taken from these animals for organ bath studies (spontaneous contractions) and microelectrode studies (slow waves). The expression of NO-GC and other members of the NO/cGMP signaling cascade will be investigated using immunohistochemistry. In addition, the ex vivo motility with isolated jejunum and colon from these KO animals will be measured. In all subprojects, we will investigate whether activation of the NO/cGMP system by the novel NO-GC activators/stimulators Bay 41-2272 or Bay 58-26678 (Cinaciguat) have a therapeutic potential with regards to gut motility. Data from murine tissues will finally be correlated to data obtained from human tissues. In summary, our NO-GC KO mice will help to elucidate how slow waves spontaneous contractions are interconnected and regulated by the nitrergic system.