Ghrelin: a gut-brain hormone: effect of gastric bypass surgery

Ghrelin is a newly recognized gastric hormone with orexigenic and adipogenic properties, produced primarily by the stomach. Ghrelin is reduced in obesity. Weight loss is associated with an increase in fasting plasma ghrelin. We assessed the effect of massive weight loss on plasma ghrelin concentrations and its correlation with serum leptin levels and the presence of type 2 diabetes mellitus (DM) in severely obese patients.

A prospective study was conducted on 28 morbidly obese women (BMI 56.3 +/- 10.2 kg/m2) who underwent gastric bypass, divided into 2 groups: 14 non-diabetics (NGT) and 14 type 2 diabetics (DM2). Ghrelin and leptin were evaluated before silastic ring transected vertical gastric bypass, and again 12 months postoperatively.

Fasting plasma ghrelin concentrations were 56% lower in NGT and 59% lower in DM2 compared with a lean control group (P < 0.001). There was no difference in ghrelin levels between NGT and DM2 groups before and after surgery (P > 0.05). Ghrelin was negatively correlated with leptin before gastric bypass surgery (r = 0.51, P < 0.01). The mean plasma ghrelin concentration decreased significantly after surgery in both groups (P < 0.001).

Ghrelin was inversely related to leptin concentrations. Presence of diabetes did not affect the ghrelin pattern. Reduced production of ghrelin after gastric bypass could be partly responsible for the lack of hyperphagia and thus for the weight loss.