stomach distension combine to reduce food intake in humans. Am J Physiol Regul Integr Comp Physiol 285: R992-R998, 2003. First published August 14, 2003 10.1152/ajpregu. 00272.2003.-The aim of this study was to test the hypothesis that gastric distension can enhance the effect of cholecystokinin (CCK) on reduction of food intake in men and women. Eight normal-weight subjects of each gender were tested four times each with either CCK or saline infusion crossed with gastric distension or no distension. Intravenous infusion of a low dose of CCK octapeptide (CCK-8; 112 ng/min for 23 min) combined with a subthreshold gastric distension induced by a water-filled balloon (300 ml) resulted in a significant (means Ϯ SED: 191 Ϯ 61 g in men, 209 Ϯ 61 g in women, and 200 Ϯ 43 g combined) reduction in intake of a liquid meal compared with saline infusion and unfilled gastric balloon. This combined effect was the result of a large and significant CCK effect when the stomach was distended (CCK vs. saline with distension: 169 Ϯ 43 g) and a small and insignificant distension effect (distension vs. no distension without CCK: 31 Ϯ 43 g). The CCK effect alone on intake (CCK vs. saline) without distension was not significant in men (72 Ϯ 61 g) but was significant in women (121 Ϯ 61 g). These results are consistent with the hypothesis that CCK's suppression of food intake is enhanced when the stomach is distended. satiety; feeding; gastric distension CHOLECYSTOKININ (CCK), a peptide hormone released by the duodenum mainly in the presence of digestion products of fats and proteins (5), reduces food intake in a variety of species, including humans (see Ref. 21 for a review). Physiologically, CCK stimulates pancreatic enzyme secretion (8), induces gall bladder contractions (1), increases neural activity in the gastric vagal afferents (18), relaxes the stomach, constricts the pylorus (13, 20), and inhibits gastric emptying when food is in the stomach (2, 12), thereby increasing gastric distension.It has been suggested that the increased gastric distension induced by slowing of gastric emptying may be the mechanism by which CCK reduces food intake (15). In support of this hypothesis, Moran and McHugh (15) reported that in monkeys a saline preload was necessary to decrease food intake after a low dose of CCK. In humans, Muurahainen et al. (17) demonstrated that intake of a test meal was significantly lower when CCK octapeptide (CCK-8) was given after a 500-g but not a 100-g soup preload. Without both CCK and the larger preload, no significant decrease in intake was observed. CCK infusion significantly decreased gastric emptying and thereby increased the gastric volume remaining after subjects ingested 500 g of soup. The size of the gastric volume increase after CCK was 80 g (from 230 to 310 g) after 25-30 min (end of ad libitum meal) compared with saline infusion (16). However, the reduction in gastric emptying also reduced the amount of nutrients entering the intestine. Therefore, the question was which of the stimuli provided by the ...
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