Inhibitory effects and mechanisms of intestinal electrical stimulation on gastric tone, antral contractions, pyloric tone, and gastric emptying in dogs

Abstract

The aim of this study was to investigate the effects and mechanisms of intestinal electrical stimulation (IES) on gastric tone, antral and pyloric contractions, and gastric emptying in dogs. Female hound dogs were equipped with a duodenal or gastric cannula, and one pair of serosal electrodes was implanted in the small intestine. The study consisted of five different experiments. Liquid gastric emptying was assessed by collection of chyme from the duodenal cannula in a number of sessions with and without IES and with and without N-nitro-L-arginine (L-NNA). Postprandial antral and pyloric contractions were measured with and without IES and in the absence and presence of L-NNA or phentolamine by placement of a manometric catheter into the antrum and pylorus via the duodenal cannula. Gastric tone was assessed by measurement of gastric volume at a constant pressure. Gastric emptying was substantially and significantly delayed by IES or L-NNA compared with the control session. IES-induced delay of gastric emptying became normal with addition of L-NNA. IES reduced gastric tone, which was blocked by L-NNA. IES also inhibited antral contractions (frequency and amplitude), and this inhibitory effect was not blocked by L-NNA but was blocked by phentolamine. IES alone did not affect pyloric tone or resistance, but IES ϩ L-NNA decreased pyloric tone. In conclusion, IES reduces gastric tone via the nitrergic pathway, inhibits antral contractions via the adrenergic pathway, does not affect pyloric tone, and delays liquid gastric emptying. IES-induced delay of gastric emptying is attributed to its inhibitory effects on gastric motility. gastrointestinal motility; gastric pacing ELECTRICAL STIMULATION as a potential modality for treatment of morbid obesity is gaining more and more attention (15, 16), since the conventional behavior modifications and pharmacotherapies have not been effective in the long term (11, 29) and surgical interventions result in a high rate of mortality and morbidity (4,9,21,42,46). Gastric electrical stimulation (GES) has been under clinical investigation for the treatment of morbid obesity, and preliminary data from studies of the effects of GES on food intake and weight loss have been encouraging but inconclusive (15, 16).The proximal small intestine plays an important role in regulating gastric emptying (30), optimizing nutrient absorption (26), and signaling satiety in the central nervous system (20). Because intestinal electrical stimulation (IES) may have multiple effects on gastrointestinal functions, including gastric emptying, small bowel transit, nutrient absorption, and feedback signaling of satiety to the central nervous system, it is a very attractive alternative option for treatment of obesity. In 1977, Kelly and Code (28) showed that distal duodenal pacing caused duodenal-gastric reflux of BaSO 4 in dogs and a 25% reduction of the rate of liquid gastric emptying. However, there has been a lack of follow-up studies of the inhibitory effects of IES on gastrointestinal motility and related m...

Pulse Width-Dependent Effects of Intestinal Electrical Stimulation for Obesity: Role of Gastrointestinal Motility and Hormones

“…Acceleration in gastric emptying of solid food, which precipitates hunger and frequent eating, was reported in obese subjects [44][45][46] and DIO rats [16,47]. IES with long pulses of 100 to 300 ms was noted to reduce gastric tone and delay gastric emptying in canine [48,49] and rats [13]. In the present study, IES of 3 ms was able to delay solid gastric emptying in addition to its effect on intestinal transit.…”

Central neuronal mechanisms of intestinal electrical stimulation: Effects on duodenum distention-responsive (DD-R) neurons in the VMH of rats

“…In one previous canine study, IES with long pulses was shown to inhibit gastric tone and the inhibitory effect was mediated by both vagal and nitrergic pathways [18]. In another canine study, IES with long pulses was reported to inhibit antral contractions and delay gastric emptying [20]. Similarly, intestinal contractions in dogs were also attenuated with IES of long pulses and the inhibitory effect was mediated via the sympathetic pathway [6].…”

Prokinetic effects of mirtazapine on gastrointestinal transit

“…Each dog was studied for four sessions in a randomized order: control, mirtazapine (45 mg), RD, and RD ϩ mirtazapine (45 mg). Gastric tone and accommodation were assessed using an established method of Barostat (Distender Series IIR, G & J Electronics, Willowdale, Ontario, Canada) (36,41,45). Gastric volume was recorded for 30 min in the fasting state and 30 min after a liquid meal (237 ml, 240 kcal, Boost) in the sessions without RD, and for 60 min in the fasting state and 60 min after the liquid meal in the sessions with RD, in which RD was performed during the second 30-min fasting period and first 30-min postprandial period.…”