Ameliorating Effects and Mechanisms of Intra-Operative Vagal Nerve Stimulation on Postoperative Recovery After Sleeve Gastrectomy in Rats

Purpose: Sleeve gastrectomy is a common bariatric procedure. The aim of this study was to explore the effects and mechanisms of intra-operative vagal nerve stimulation (iVNS) on postoperative recovery after sleeve gastrectomy in rats. Materials and Methods: Rats were randomly divided into groups of sham-iVNS (n = 12) and iVNS (n = 12), and received sleeve gastrectomy, and were implanted electrodes for the electrocardiogram (ECG) and gastric pace-making activity or slow wave (GSW). iVNS or sham-iVNS was performed during surgery. Postoperative animal behaviors, pain, gastrointestinal functions, autonomic functions, inflammatory cytokines, and hormones in plasma were assessed. Results: In comparison with sham-iVNS, (1) iVNS accelerated the first drinking time (P = 0.01) and first defecation time (P = 0.02), increased the weight of stool in postoperative day (POD) 1 (P = 0.01) and POD3 (P = 0.01), and reduced postoperative pain at 24 h after surgery (P = 0.01); (2) physiologically, iVNS improved gastric emptying (P < 0.01) at 72 h after surgery, and increased the dominant frequency (P < 0.01) and the percentage of normal GSW (P = 0.04) at 6 h after surgery; (3) mechanistically, iVNS increased vagal activity and decreased sympathovagal ratio at 6 h (vagal, P < 0.01; sympathovagal ratio, P < 0.01) and 24 h (vagal, P = 0.02; sympathovagal ratio, P = 0.01) after surgery, increased the plasma pancreatic polypeptide (P = 0.03) at 1 h after surgery, and decreased the plasma tumor necrosis factor-α (TNF-α) at 1 h (P = 0.02) and 6 h (P = 0.03) and the plasma interleukin-6 (IL-6) at 1 h (P = 0.02) after surgery. Conclusion: Intra-operative VNS is effective in accelerating post-surgical recovery in rats after sleeve gastrectomy by enhancing gastric pace-making activity and suppressing proinflammatory cytokines mediated via the autonomic mechanisms.