Grabauskas Gintautas, Wu Xiaoyin, Song Il, Zhou Shi-Yi, Lanigan Thomas, Owyang Chung
Division of Gastroenterology, Department of Internal Medicine, Ann Arbor, Michigan.
Department of Internal Medicine, Center for Gene Therapy, Ann Arbor, Michigan.
Gastroenterology. 2016 Nov;151(5):910-922.e7. doi: 10.1053/j.gastro.2016.07.029. Epub 2016 Jul 27.
BACKGROUND & AIMS: Patients with diabetes have defects in the vagal afferent pathway that result in abnormal gastrointestinal function. We investigated whether selective increased activation of the 2-pore domain potassium channel TRESK (2-pore-domain weak inward-rectifying potassium channel-related spinal cord potassium channel) contributes to nodose ganglia (NG) malfunction, disrupting gastrointestinal function in diabetic rats.
We conducted whole-cell current-clamp and single-unit recordings in NG neurons from diabetes-prone BioBreeding/Worcester rats and streptozotocin-induced diabetic (STZ-D) rats and compared them with control rats. NG neurons in rats or cultured NG neurons were exposed to pharmacologic antagonists and/or transfected with short hairpin or small interfering RNAs that reduced expression of TRESK. We then made electrophysiologic recordings and studied gastrointestinal functions.
We observed reduced input resistance, hyperpolarized membrane potential, and increased current threshold to elicit action potentiation in NG neurons of STZ-D rats compared with controls. NG neuron excitability was similarly altered in diabetes-prone rats. In vivo single-unit NG neuronal discharges in response to 30 and 60 pmol cholecystokinin octapeptide were significantly lower in STZ-D rats compared with controls. Reducing expression of the TRESK K channel restored NG excitability in vitro and in vivo, as well as cholecystokinin 8-stimulated secretion of pancreatic enzymes and secretin-induced gastrointestinal motility, which are mediated by vago-vagal reflexes. These abnormalities resulted from increased intracellular Ca in the NG, activating calcineurin, which, in turn, bound to an nuclear factor of activated T cell-like docking site on the TRESK protein, resulting in neuronal membrane hyperpolarization.
In 2 rate models of diabetes, we found that activation of the TRESK K channel reduced NG excitability and disrupted gastrointestinal functions.
糖尿病患者存在迷走神经传入通路缺陷，导致胃肠功能异常。我们研究了选择性增强双孔结构域钾通道TRESK（双孔结构域弱内向整流钾通道相关脊髓钾通道）的激活是否会导致结状神经节（NG）功能障碍，从而扰乱糖尿病大鼠的胃肠功能。
我们对易患糖尿病的BioBreeding/Worcester大鼠和链脲佐菌素诱导的糖尿病（STZ-D）大鼠的NG神经元进行了全细胞电流钳和单单位记录，并与对照大鼠进行比较。将大鼠的NG神经元或培养的NG神经元暴露于药理学拮抗剂和/或用短发夹或小干扰RNA转染，以降低TRESK的表达。然后我们进行电生理记录并研究胃肠功能。
与对照组相比，我们观察到STZ-D大鼠的NG神经元输入电阻降低、膜电位超极化以及引发动作电位增强的电流阈值增加。易患糖尿病的大鼠的NG神经元兴奋性也有类似改变。与对照组相比，STZ-D大鼠体内对30和60 pmol八肽胆囊收缩素产生反应的单单位NG神经元放电明显减少。降低TRESK钾通道的表达可在体外和体内恢复NG兴奋性，以及胆囊收缩素8刺激的胰酶分泌和促胰液素诱导的胃肠蠕动，这些都是由迷走-迷走反射介导的。这些异常是由于NG中细胞内钙增加，激活钙调神经磷酸酶，进而与TRESK蛋白上活化T细胞核因子样对接位点结合，导致神经元膜超极化。
在两种糖尿病大鼠模型中，我们发现TRESK钾通道的激活降低了NG兴奋性并扰乱了胃肠功能。
