Abstract：
The mechanisms of diabetes-related gastrointestinal dysmotility remains unclear. This study aimed to investigate the effect and mechanisms of proinflammatory adipokine visfatin (VF) in the contractile dysfunction of diabetic rat colonic smooth muscle. Twenty Sprague-Dawley rats were randomly divided into control and type 2 diabetes mellitus groups. VF levels in the serum and colonic muscle tissues were tested, the time of the bead ejection and contractility of colonic smooth muscle strips were measured, and the expression of ATP-sensitive potassium (KATP) channels in the colonic muscle tissues was analyzed. In vitro, we tested VF\'s effects on intracellular reactive oxygen species (ROS) levels, NF-κB\'s nuclear transcription, KATP channel expression, intracellular Ca2+ concentrations, and myosin light chain (MLC) phosphorylation in colonic smooth muscle cells (CSMCs). The effects of NAC (ROS inhibitor) and BAY 11-7082 (NF-κB inhibitor) on KATP expression were also tested. Diabetic rats showed elevated VF levels in serum and colonic muscle tissues, a delayed distal colon ejection response time, weakened contractility of colonic smooth muscle strips, and increased KATP channel expression in colonic muscle tissues. VF significantly inhibited the contractility of colonic smooth muscle strips from normal rats. In cultured CSMCs, VF caused ROS overload, increased NF-κB nuclear transcription activity and increased expression of Kir6.1, eventually reducing intracellular Ca2+ levels and MLC phosphorylation. NAC and BAY 11-7082 inhibited the VF-induced Kir6.1 upregulation. In conclusion, VF may cause contractile dysfunction of CSMCs by upregulating the expression of the Kir6.1 subunit of KATP channels via the ROS/NF-κB pathway and interfering with Ca2+ signaling.
摘要：
与糖尿病相关的胃肠动力障碍的机制尚不清楚。本研究旨在探讨促炎症脂肪因子内脂素(VF)在糖尿病大鼠结肠平滑肌收缩功能障碍中的作用及其机制。将20只Sprague-Dawley大鼠随机分为对照组和2型糖尿病组。检测血清和结肠肌肉组织中的VF水平，测量结肠平滑肌条的珠弹出时间和收缩力，并分析了结肠肌肉组织中ATP敏感性钾（KATP）通道的表达。体外，我们测试了VF对细胞内活性氧（ROS）水平的影响，NF-κB核转录,KATP通道表达，细胞内Ca2+浓度，和结肠平滑肌细胞（CSMC）中的肌球蛋白轻链（MLC）磷酸化。还测试了NAC(ROS抑制剂)和BAY11-7082(NF-κB抑制剂)对KATP表达的影响。糖尿病大鼠血清和结肠肌肉组织中VF水平升高，远端结肠射血反应时间延迟，结肠平滑肌条收缩性减弱，结肠肌肉组织中KATP通道表达增加。VF显著抑制正常大鼠结肠平滑肌条的收缩力。在培养的CSMC中，VF导致ROS过载，NF-κB核转录活性增加，Kir6.1表达增加，最终降低细胞内Ca2+水平和MLC磷酸化。NAC和BAY11-7082抑制VF诱导的Kir6.1上调。总之,VF可能通过ROS/NF-κB途径上调KATP通道Kir6.1亚基的表达并干扰Ca2信号传导，从而导致CSMC的收缩功能障碍。
