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Characteristics of glucose and maltose preloads that inhibit feeding in 12-day-old rats
A Weller1, I H Gispan, G P Smith
1Department of Psychology, Bar Ilan University, Ramat Gan, Israel.
Insights
Young rats show inhibitory control over food intake by postnatal day 12. Hypertonic preloads in the stomach or intestine reduce feeding, with cholecystokinin (CCK) playing a role only with soybean trypsin inhibitor (SBTI).
Area of Science:
- Neuroscience
- Developmental Biology
- Physiology
Background:
- Early life feeding behaviors are crucial for development.
- Understanding the mechanisms of appetite regulation in neonates is important.
- Inhibitory control of food intake develops early in life.
Purpose of the Study:
- To investigate nonvolumetric inhibitory control of food intake in rats at postnatal day 12.
- To determine the role of osmotic load and cholecystokinin (CCK) in preload-induced satiety.
Main Methods:
- Rats received various preloads (glucose, maltose, 2-DG, NaCl, SBTI, water) or sham intubation before a milk diet.
- The CCK(A) receptor antagonist devazepide or vehicle was administered to assess CCK mediation.
- Food intake was measured as percent body weight gain.
Main Results:
- All preloads significantly reduced food intake compared to sham intubation.
- Glucose and 2-deoxy-D-glucose (2-DG) showed similar inhibitory effects, suggesting osmotic properties are key.
- Devazepide only attenuated the intake inhibition caused by soybean trypsin inhibitor (SBTI), indicating CCK's limited role.
Conclusions:
- Hypertonic stimuli in the gastrointestinal tract provide inhibitory control of food intake by postnatal day 12.
- Osmotic properties of preloads significantly influence early-life satiety.
- Endogenous cholecystokinin (CCK) plays a minimal role in mediating preload-induced satiety in young rats, except for SBTI.
Abstract:
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.