EFFECTS OF A SPECIFIC CCK-A ANTAGONIST, LOXIGLUMIDE, ON POSTPRANDIAL MOOD AND SLEEPINESS

Previous studies have demonstrated that feelings of sleepiness increas e after ingestion of a fat-rich meal. The aim of the study was to test the hypothesis that postprandial sleepiness is mediated by cholecysto kinin (CCK) acting on CCK-A receptors. A double-blind crossover study was conducted. Twelve male volunteers ate a high-fat morning meal [54% energy fat, 41% energy carbohydrate (CHO)]. On one day they received an i.v. infusion of Loxiglumide, a CCK-A receptor antagonist (30 mg/kg /h for 10 min then 10 mg/kg/h for 3 h 10 min). On another day the prot ocol was repeated except a saline placebo infusion was given at simila r rates as the Loxiglumide, starting 20 min before the meal. Subjects' mood and sleepiness were monitored throughout using questionnaires an d performance tasks. The results indicate that ratings of vigour were significantly lower during the Loxiglumide infusion than during the sa line infusion, [F(1,10)=6.65; p=0.027]. Subjects who were infused with Loxiglumide on their first test day felt significantly (p < 0.05) mor e fatigued, sleepy and tense and less vigorous, less efficient and had lower energetic arousal during the Loxiglumide infusion than during t he saline infusion. In conclusion, the results suggest that the postpr andial decline in feelings of alertness after a fat-rich meal is not m ediated solely by CCK acting through CCK-A receptors.