Recent studies in animals have shown that ghrelin stimulates upper gastrointestinal motility through the vagus and enteric nervous system.
Dr Jan Tack and colleagues from Belgium investigated the effect of administration of ghrelin on upper gastrointestinal motility.
The investigative team also elucidated its mode of action by measuring plasma levels of gastrointestinal hormones in humans.
The team included 9 healthy volunteers, of which 4 were males, aged 22 to 35 years, in a double blind, randomized, crossover trial.
The volunteers underwent combined antroduodenal manometry and proximal stomach barostat study on 2 separate occasions at least 1 week apart.
|Ghrelin increased plasma levels of pancreatic polypeptide|
Saline or ghrelin 40 µg was administered intravenously over 30 minutes, at 20 minutes after the occurrence of phase III of the migrating motor complex.
Ghrelin, motilin, pancreatic polypeptide, glucagon, and somatostatin were measured by radioimmunoassay in blood samples obtained at 15-30 minute intervals.
The influence of ghrelin or saline on migrating motor complex phases, hormone levels, and intraballoon volume was compared using paired t test.
The investigators also used ANOVA, and 2 testing for the statistical analyses.
The team found that spontaneous phase III occurred in all subjects, with a gastric origin in 4.
Administration of ghrelin induced a premature phase III, compared with saline.
The investigators observed that intraballoon volumes before infusion were similar but ghrelin induced a longlasting decrease in intraballoon volume.
Administration of ghrelin increased plasma levels of pancreatic polypeptide and ghrelin.
However, the team noted that motilin, somatostatin, and glucagon levels were not altered.
Dr Tack's team commented, “In humans, administration of ghrelin induces a premature gastric phase III of the migrating motor complex, which is not mediated through release of motilin.”
“This is accompanied by prolonged increased tone of the proximal stomach.”