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

NO敏感的鸟苷酸环化酶参与多种生理调节过程，如血压调节、突触可塑性和胃肠运动等。该酶被一氧化氮(NO)激活，催化第二信使cGMP的形成。我们已经产生了NO-GC被全局删除的小鼠。这些小鼠患有胃肠动力障碍、血压升高和过早死亡。然而，导致个体表型的细胞/组织类型尚不清楚。全球GCKO小鼠胃肠道动力下降的基础是缺乏氮能(NO介导的)松弛。硝酸能松弛的确切机制仍未完全阐明。由于NO-GC表达于平滑肌细胞(SMC)、Cajal间质细胞(ICC)、成纤维细胞样细胞(FLC)，甚至某些神经元，参与介导NO作用的细胞类型尚不清楚。在ICCs中，有两种不同的亚型具有不同的功能：肌内ICC(ICC-My)负责起搏电位，而肌内ICC(ICC-IM)负责肠道神经传递。神经元释放的NO对这两种ICC的影响正在被广泛讨论。在这个项目中，我们想要研究NO/cGMP如何调节起搏系统的节律性和结肠和空肠不同部分的自发收缩。我们将在全球范围内或专门在SMC、ICC或两者中使用缺乏NO-GC的KO小鼠。这些动物的空肠和结肠的不同部分将被用于器官浴研究(自发收缩)和微电极研究(慢波)。NO-GC和NO/cGMP信号级联的其他成员的表达将用免疫组织化学方法进行研究。此外，还将测量这些KO动物的空肠和结肠的体外运动。在所有子项目中，我们将调查新型NO-GC激活剂/刺激剂BAY 41-2272或BAY 58-26678(Cinaciguat)激活NO/cGMP系统是否在肠道运动方面具有治疗潜力。来自老鼠组织的数据最终将与从人类组织获得的数据相关联。综上所述，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联系并受硝能系统调节的。

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.