Untangling the effects of hunger, anxiety, and nausea on energy intake during intravenous cholecystokinin octapeptide (CCK-8) infusion

Infusions of cholecystokinin (CCK) may exert their effects on appetite by i nducing feelings of nausea or anxiety. In this double blind, placebo contro lled crossover study, the impact of these effects on appetite were examined . Fifteen male subjects received a 20 min i.v. infusion of cholecystokinin octapeptide (CCK-8) (4 ng/kg/min) or saline. The infusion commenced 20 min after a soup preload and 10 min before an ad libitum test meal. Visual anal ogue scales of appetite and mood were measured over 3 h, and subjects were instructed to report any other sensations they experienced over this time. CCK-8 significantly reduced premeal hunger, elevated premeal anxiety, and r educed energy intake at the ad libitum test meal. Meal duration and rate of eating (kcal/min) were also significantly reduced after CCK-8. After the s maller meal with CCK-8, hunger rose quickly to a higher level than with pla cebo. The return of hunger was commensurate with the smaller amount of ener gy consumed and indicated that CCK did not exert an enduring effect on hung er suppression. A significant correlation was found between the reduction i n energy intake and hunger (r = 0.75 p < 0.01), but not with anxiety (r = 0 .15 not significant). Analysts were performed separately on subjects who di d (n = 8), or did not (n = 7) report gastrointestinal disturbance. Energy i ntake was reduced by 56.6% and 44.6%, respectively. These results indicate that, although feelings of anxiety and nausea may accompany CCK infusions, they are not necessary for the effects of CCK on appetite. These data provi de support for a role of CCK in satiety. (C) 1998 Elsevier Science Inc.