Prokinetic effects of a ghrelin receptor agonist GHRP-6 in diabetic mice

Abstract

Aim: To investigate the effects of a ghrelin receptor agonist GHRP-6 on delayed gastrointestinal transit in alloxan-induced diabetic mice. Methods: A diabetic mouse model was established by intraperitoneal injection with alloxan. Mice were randomized into two main groups: normal mice and diabetic mice treated with GHRP-6 at doses of 0, 20, 50, 100 and 200 μg/kg ip. Gastric emptying (GE), intestinal transit (IT), and colonic transit (CT) were studied in mice after they had a phenol red meal following injection of GHRP-6. Based on the most effective GHRP-6 dosage, atropine was given at 1 mg/kg for 15 min before the GHRP-6 injection for each measurement. The mice in each group were sacrificed 20 min later and the percentages of GE, IT, and CT were calculated. Results: Percentages of GE, IT, and CT were significantly decreased in diabetic mice as compared to control mice. In the diabetic mice, GHRP-6 improved both GE and IT, but not CT. The most effective dose of GHRP-6 was 200 μg/kg and atropine blocked the prokinetic effects of GHRP-6 on GE and IT. Conclusion: GHRP-6 accelerates delayed GE and IT, but has no effect on CT in diabetic mice. GHRP-6 may exert its prokinetic effects via the cholinergic pathway in the enteric nervous system, and therefore, has therapeutic potential for diabetic patients with delayed upper gastrointestinal transit. © 2008 The WJG Press. All rights reserved.