Increased Density of Ghrelin-Expressing Cells in the Gastric Fundus and Body in Prader-Willi Syndrome

Abstract

The levels of ghrelin, an orexigenic hormone secreted by oxyntic cells in the digestive tract, are elevated in Prader-Willi syndrome (PWS) and GH deficiency (GHD) patients. In this study, we hypothesized that the hyperghrelinemia observed in PWS is related to IGF-I or GH/IGF axis deficiency. We investigated the densities of ghrelin-expressing cells (GECs), the amounts of ghrelin in gastric tissues, and ghrelin levels in plasma in 16 PWS patients and compared these results with those of 13 GHD patients and comparison groups (19 normal lean and 10 normal obese subjects). In the gastric body and fundus, 2- to 3-fold increases in the numbers of GECs (P < 0.001) and in the amounts of ghrelin (P < 0.018) were noted in PWS patients vs. comparison groups, whereas GEC numbers in GHD patients were similar to those of the comparison group despite elevated fasting plasma ghrelin levels. In addition, IGF-I sd scores in PWS were not found to be correlated with GEC densities, the amounts of ghrelin expressed in gastric tissues, or plasma ghrelin levels. Our results suggest that IGF-I or GH/IGF axis deficiency appears to be unrelated to observed GEC increases in the stomach of patients with PWS.