Intestinal Electrical Stimulation Enhances Release of Postprandial Incretin Hormones Via Cholinergic Mechanisms.

Abstract

Intestinal electrical stimulation (IES) has been reported to reduce body weight and improve glucose tolerance in obese and diabetic rats. Our study aimed to investigate possible IES mechanisms involving incretin hormones using intraduodenal glucose infusion in rats. We hypothesized that the enhanced release of postprandial glucagon-like peptide-1 (GLP-1) at early phase by IES was mediated through neuro/paracrine mechanisms involving the vagal nerve and glucose-dependent insulinotropic peptide (GIP). Fifteen normal male Sprague-Dawley rats chronically implanted with duodenal electrodes for IES, and an intra-duodenum catheter for the infusion of glucose were studied in a series of sessions with IES of different parameters with and without atropine and M3 receptor antagonist. Blood samples were collected via the tail vein for the measurement of blood glucose, and plasma GLP-1, and GIP. (1) Compared to sham-IES, IES of 0.3ms reduced blood glucose by 16.5-28.4% between 30 and 120min (all time points p < 0.05), and IES of 3-ms reduced blood glucose at 60 (12.6%) and 90min (11.8%). IES of 0.3ms showed a greater hypoglycemic effect than 3ms (p = 0.024) at 30min. (2) IES elevated plasma GLP-1 with 0.3ms (p = 0.001) and with 3ms p = 0.03). (3) IES substantially elevated plasma GIP with 0.3ms (p = 0.002) and with 3ms (p < 0.001). (4) Pretreatment of atropine and the M3 receptor antagonist 4-DAMP blocked the effects of IES on GLP-1, GIP, and blood glucose. IES reduces postprandial blood glucose by enhancing the release of GLP-1 and GIP mediated via the cholinergic mechanism.