Effect of naloxone, domperidone and idazoxan on the delay in gastric emptying induced by ileal lipid

Studies were carried out on 22 healthy male volunteers to investigate whether intravenous administration of either the opiate antagonist, naloxone, or the dopamine antagonist, domperidone, or the alpha 2-adrenoreceptor antagonist, idazoxan, could reverse the delay in gastric emptying induced by ileal infusion of lipid emulsion. Ileal infusion of 50% lipid emulsion significantly delayed the rate of gastric emptying compared with ileal infusion of isotonic saline (P less than 0.01). Intravenous infusion of naloxone (20 micrograms kg-1 hour-1) or prior administration of either intravenous domperidone (20 mg) or idazoxan (0.2 mg kg-1) did not inhibit the delay in gastric emptying induced by ileal infusion of lipid emulsion. These observations indicate that feedback regulation of gastric emptying by ileal lipid does not appear to be mediated by either dopaminergic or enkephalinergic neurons, nor by alpha 2-adrenoreceptors.