Division of Gastroenterology, Department of Internal Medicine, University of Michigan, 3912 Taubman Center, SPC 5362, 1500 East Medical Center Drive, Ann Arbor, MI 48109, USA.
Endocrinology. 2013 Jan;154(1):296-307. doi: 10.1210/en.2012-1382. Epub 2012 Dec 4.
Glucosensing nodose ganglia neurons mediate the effects of hyperglycemia on gastrointestinal motility. We hypothesized that the glucose-sensing mechanisms in the nodose ganglia are similar to those of hypothalamic glucose excited neurons, which sense glucose through glycolysis. Glucose metabolism leads to ATP-sensitive potassium channel (K(ATP)) channel closure and membrane depolarization. We identified glucosensing elements in the form of glucose transporters (GLUTs), glucokinase (GK), and K(ATP) channels in rat nodose ganglia and evaluated their physiological significance. In vitro stomach-vagus nerve preparations demonstrated the gastric vagal afferent response to elevated glucose. Western blots and RT-PCR revealed the presence of GLUT1, GLUT3, GLUT4, GK, and Kir6.2 in nodose ganglia neurons and gastric branches of the vagus nerve. Immunocytochemistry confirmed the expression of GLUT3, GK, and Kir6.2 in nodose ganglia neurons (46.3 ± 3%). Patch-clamp studies detected glucose excitation in 30% (25 of 83) of gastric-projecting nodose ganglia neurons, which was abolished by GLUT3 or GK short hairpin RNA transfections. Silencing GLUT1 or GLUT4 in nodose ganglia neurons did not prevent the excitatory response to glucose. Elevated glucose elicited a response from 43% of in vitro nerve preparations. A dose-dependent response was observed, reaching maximum at a glucose level of 250 mg/dl. The gastric vagal afferent responses to glucose were inhibited by diazoxide, a K(ATP) channel opener. In conclusion, a subset of neurons in the nodose ganglia and gastric vagal afferents are glucoresponsive. Glucosensing requires a GLUT, GK, and K(ATP) channels. These elements are transported axonally to the gastric vagal afferents, which can be activated by elevated glucose through modulation of K(ATP) channels.
葡萄糖感应性迷走神经节神经元介导高血糖对胃肠动力的影响。我们假设迷走神经节中的葡萄糖感应机制与下丘脑葡萄糖兴奋神经元相似,后者通过糖酵解感应葡萄糖。葡萄糖代谢导致 ATP 敏感性钾通道(KATP)通道关闭和膜去极化。我们在大鼠迷走神经节中鉴定了葡萄糖感应元件,形式为葡萄糖转运体(GLUTs)、葡萄糖激酶(GK)和 KATP 通道,并评估了它们的生理意义。在离体胃-迷走神经标本中,我们证明了升高葡萄糖对胃迷走传入的反应。Western blot 和 RT-PCR 显示 GLUT1、GLUT3、GLUT4、GK 和 Kir6.2 存在于迷走神经节神经元和迷走神经胃支中。免疫细胞化学证实 GLUT3、GK 和 Kir6.2 在迷走神经节神经元中表达(46.3±3%)。膜片钳研究检测到 30%(83 个中的 25 个)胃投射性迷走神经节神经元对葡萄糖的兴奋,该兴奋可被 GLUT3 或 GK 短发夹 RNA 转染消除。在迷走神经节神经元中沉默 GLUT1 或 GLUT4 并不能阻止对葡萄糖的兴奋反应。升高的葡萄糖引起 43%的离体神经标本产生反应。观察到剂量依赖性反应,在葡萄糖水平为 250mg/dl 时达到最大值。葡萄糖对胃迷走传入的反应被 KATP 通道开放剂二氮嗪抑制。总之,迷走神经节和胃迷走传入中的一部分神经元对葡萄糖有反应。葡萄糖感应需要 GLUT、GK 和 KATP 通道。这些元件被轴突运输到胃迷走传入,通过调节 KATP 通道,它们可以被升高的葡萄糖激活。