Meal form influences CCK release and maximum satiation in healthy subjects.

Background and aim: Meal-induced gastric distension and Cholecys- tokinin (CCK) are involved in the food intake. The relationship between meal gastric distension and CCK release have not been studied by non- invasive technique. We studied gastric volumes changes by Magnetic Resonance Imaging (MRI) and CCK serum levels after water preload and liquid (LM) and solid (SM) meals. Material and methods: Ten healthy subjects (4 F; Age 22 ± 3; BMI 23 ± 1) were studied on two days. Two test meals, a SM and LM with a similar nutrient composition (carbohydrate 46%; fat 32%; protein 22%) and energy content were used. Subjects were requested to ingest constant Kcal at 5 min interval (100 kcal/5 min) and to score their satiation level on a visual analogue scale graded 0–5 (1=threshold, 5= maximum satiation- MS). Experiment was scheduled as following: -10 min: 300 ml water preload (WPL); 0 min: solid or liquid meal until MS. CCK levels (ELISA, Phoenix, USA) were measured at baseline, after WPL, at 30, 60, 120 min of meal test. Gastric volume was evaluated by 1.5 T MRI at baseline, after water load, at MS and 120 min. Total (TGV) and proximal (PGV) gastric volumes (as difference respect to baseline) were manually traced by a trained observer. Data are presented as mean ± SD. Results: Kcal ingested and time to reach MS were significantly higher during SM (783 ± 244 kcal; 44 ± 14 min) than LM (630 ± 353 p < 0.01; 31 ± 17 p < 0.01). CCK serum peaks and time to peak were not different in LM and SM (1.62 ± 0.72 ng/ml vs 1.26 ± 0.87, and 41 ± 21 min vs 39 ± 14, respectively). TGV and PGV were not different between the two meal groups after WPL (SM: 271 ± 59 ml, 72 ± 46 vs LM: 309 ± 55, 74 ± 29) and at MS (SM: 554 ± 203 ml, 92 ± 32 vs LM: 560 ± 301, 132 ± 60). However TGV after WPL significantly correlated with CCK peaks in both meal groups (SM: r=0.73; p=0.016 and LM: r=0.62; p=0.049). PGV correlated with CCK peak in LM but not in SM (r=0.72, p=0.015; r=0.026, p=0.82). Conclusions: The MS induced by SM is not depending by GV and by CCK release. In contrast, the ability of LM to induce an earlier satiation is associated to the combined effect of the proximal stomach distension and the maximum CCK release. These results suggest a partial role of both total and proximal gastric distension in to determine CCK release. This relationship appears more evident with a liquid form of meal