We compared suppression of intake of 30% sucrose produced by continuous aortal (near celiac) and intravenous infusions of cholecystokinin octapeptide (CCK-8). Adult, male Sprague-Dawley rats received 21-min infusions of saline or 100-1,600 ng CCK-8. Sucrose was available for 20 min, beginning 1 min after onset of infusions. Significant reductions in intake were produced by near-celiac infusions of 400, 800, and 1,600 ng CCK-8, but only the two highest doses affected intake when infused intravenously. In a second experiment, which replicated previous observations, near-celiac bolus infusions of 70 ng CCK-8 significantly reduced sucrose intake but intravenous infusions did not. Behavioral observations indicated that although bolus infusions produced immediate disruption of feeding, suggesting an aversive effect, effects of continuous CCK-8 infusions on temporal intake patterns were consistent with enhancement of satiety. These data provide further evidence that CCK-8 acts on a site within the upper gastrointestinal tract to produce satiety.
