Implantable Colonic Electrical Stimulation Improves Gastrointestinal Transit and Defecation in a Canine Constipation Model

Objectives: Colonic electrical stimulation (CES) may have a therapeutic potential for slow transit constipation (STC). This study aimed to evaluate the effects of implantable CES on gastrointestinal transit and defecation, and explore its mechanisms in a canine STC model. Methods: Two pairs of electrodes were implanted in each of the proximal colon and rectosigmoid junction (RSJ). Parameters were individualized according to the symptoms of the stimulated dogs. In the STC model, gastrointestinal transit and defecation were assessed to evaluate the effects of double-site CES, and of double-site CES combined with atropine or N-nitro-L-arginine (L-NNA) in a crossover design. Results: Individualized parameters varied among the animals. The CES significantly shortened gastrointestinal transit time (GITT) and colonic transit time (CTT) compared with sham CES (p = 0.001 and p < 0.001, respectively). Compared with sham CES, the CES also exhibited significantly higher stool frequency and stool consistency score (p = 0.018 and p = 0.001, respectively). Co-treatment with atropine or L-NNA blocked the effects of CES on GITT, CTT, and stool consistency. The stool frequency increased by CES, however, only reduced by co-treatment with L-NNA. Conclusions: This double-site implantable CES can improve the gastrointestinal transit and defecation in a canine STC model, possibly by activating the cholinergic and nitrergic pathways. The CES mode used in this study may be proven feasible in treating STC.