Is cholecystokinin a satiety hormone? Correlations of plasma cholecystokinin with hunger, satiety and gastric emptying in normal volunteers.

This study was designed to test the putative role of plasma cholecystokinin (CCK) in eating behaviour by examining the relationships between bioassayed plasma CCK concentrations and rated sensations of satiety and hunger following the ingestion of an appetizing nutrient-dense meal and between plasma profiles of CCK and scintigraphically determined gastric emptying in nine healthy male volunteers. Mean plasma CCK levels from the whole group showed a significant negative correlation with mean hunger ratings (r = -0.64) and a positive correlation with fullness (r = +0.68). However, there was considerable interindividual variation and negative correlations with hunger were only seen in three out of nine subjects and positive correlations with fullness in four out of nine subjects. In contrast, there was a strong relationship between the plasma CCK produced over the first 2 h after the meal and the half time for gastric emptying of the meal (r = -0.81). These data do not support a direct role for circulating levels of CCK in the control of hunger and satiety following a meal. Instead, the strong correlation with gastric emptying is compatible with release of CCK in response to nutrient delivery into the small intestine.