Ghrelin is a gut
peptide that is secreted from the stomach and stimulates food intake. There are
ghrelin receptors throughout the gut and intracerebroventricular
ghrelin has been shown to increase gastric acid secretion. The aim of the present study was to examine the effects of peripherally administered
ghrelin on gastric emptying of a non-nutrient and nutrient liquid, as well as, basal and
pentagastrin-stimulated gastric acid secretion in awake rats. In addition, gastric contractility was studied in vitro. Rats equipped with a
gastric fistula were subjected to an
intravenous infusion of
ghrelin (10-500 pmol kg(-1) min(-1)) during saline or
pentagastrin (90 pmol kg(-1) min(-1)) infusion. After administration of
polyethylene glycol (PEG) 4000 with 51Cr as radioactive marker, or a liquid nutrient with (51)Cr, gastric retention was measured after a 20-min infusion of
ghrelin (500 pmol kg(-1) min(-1)). In vitro isometric contractions of segments of rat gastric fundus were studied (10(-9) to 10(-6) M).
Ghrelin had no effect on basal
acid secretion, but at 500 pmol kg(-1) min(-1)
ghrelin significantly decreased
pentagastrin-stimulated
acid secretion.
Ghrelin had no effect on gastric emptying of the nutrient liquid, but significantly increased gastric emptying of the non-nutrient liquid.
Ghrelin contracted fundus muscle strips dose-dependently (pD2 of 6.93+/-0.7).
Ghrelin IV decreased plasma
orexin A concentrations and increased plasma
somatostatin concentrations. Plasma
gastrin concentrations were unchanged during
ghrelin infusion. Thus,
ghrelin seems to not only effect food intake but also gastric motor and secretory function indicating a multifunctional role for
ghrelin in energy homeostasis.