A potential and novel therapy for obesity: Appendix electrical stimulation in dogs

Background Intestinal electrical stimulation (IES) has been introduced as a potential therapy for obesity. However, it is unknown whether the effects of IES on gastrointestinal motility and food intake are location-specific. The aim of this study was to assess the effects of "appendix" (cecum in dog) electrical stimulation (AES) on gastric tone, gastric emptying, and food intake in dogs. Methods Twelve healthy dogs were used in three experiments. In experiments 1 and 2, gastric tone and food intake were studied in six dogs implanted with a gastric cannula and one pair of stimulation electrodes in the "appendix." Experiment 3 was performed to study gastric emptying in six dogs with a duodenal cannula and one pair of stimulation electrodes in the "appendix." Results (1) AES resulted in proximal gastric distention, with gastric volume increased from 114.9±10.7 mL at baseline to 301.7±37.1 mL during AES (p=0.001), and the effect was completely blocked by a nitric oxide synthase inhibitor. (2) Gastric emptying was delayed at 90 min from 69.8±9.5% in the control session to 15.2±3.6% in the AES session (p=0.002). 3) AES reduced food intake (average daily intake over a 1-week period) by 55.4%(550.4±17.6 g at control vs. 245.7±17.1 g with AES, p<0.001). Conclusions AES reduces gastric tone via the nitrergic pathway, delays gastric emptying, and inhibits food intake in healthy dogs. These data suggest the therapeutic potential of AES for obesity. Additionally, AES is technically more feasible than electrical stimulation of the stomach or duodenum because a stimulator with electrodes may be placed into the appendix via colonoscopy.