Cholinergic regulation of ghrelin and PYY release may be impaired in obesity

Abstract

Objective: Ghrelin and PYY are both hormones derived from the gastrointestinal tract involved in appetite regulation. The cholinergic part of the vagal nerve is involved in the regulation of glucose and insulin. The aim of the study was to examine the effects of the cholinergic antagonist atropine on ghrelin, PYY, glucose and insulin under basal conditions and after meal ingestion in lean and obese subjects.

Reasearch design and Methods: 8 lean and 8 obese subjects in a randomized, double-blind, placebo controlled crossover study design with four study days in randomized order: Atropine/placebo +/− breakfast. Plasma ghrelin, PYY, insulin and glucose were measured. Hunger and satiety feelings were rated on 10 cm visual analog scales.

Results: In lean individuals atropine led to a decrease in ghrelin concentrations comparable to and non-additive with breakfast ingestion and to a significant decrease in both basal and meal induced PYY concentrations. In obese subjects atropine did not significantly change ghrelin or PYY concentrations whereas it induced a comparable increase in heart rate and in meal induced glucose concentrations in the two study groups. Only lean, but not obese subjects experienced sustained feelings of satiety after breakfast.

Conclusions: The impaired cholinergic regulation of the postprandial drop in ghrelin concentrations and rise in PYY concentrations might be part of the deregulated food intake in obese subjects.