Characteristics of glucose and maltose Preloads that inhibits Feeding in 12-day-old rats

Nonvolumetric inhibitory control of food intake during independent ingestion was studied in rats on postnatal day 12. Pups received either sham intubation or equivolumetric (5% BW) preloads of 20% (w/v) glucose, 20% maltose, 20% 2-deoxy-D-glucose (2-DG), 0.9% NaCl, 200 mg soybean trypsin-inhibitor (SBTI) or distilled water, 5 min prior to 30-min access to a milk diet spread on the floor of a beaker. To investigate if endogenous cholecystokinin mediated any of the inhibitory effects of the preloads on intake, pups were injected IP with 1 mg/kg devazepide, a specific CCK(A) receptor antagonist, or with vehicle 30 min prior to the intake test. All preloads reduced intake (measured by percent body weight gain) compared to sham intubation. Glucose (20%) reduced intake significantly more than 0.9% saline, but not more than the preload of 20% 2-DG. This suggests that the effect of glucose can be accounted for by its preabsorptive osmotic properties because 2-DG is not actively transported or metabolized. The inhibitory effect of 20% maltose may also be due to its osmotic load, but these experiments did not provide clear evidence for this. Cholecystokinin apparently did not mediate the effect of any of the preloads except SBTI, because devazepide only reduced the inhibition produced by a preload of SBTI. These results provide further evidence that hypertonic stimuli in the stomach or small intestine provide inhibitory control of food intake by postnatal day 12.