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Updated: Jun 14, 2026

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Progressive-ratio Responding for Palatable High-fat and High-sugar Food in Mice
Published on: May 3, 2012
AM 251 differentially effects food-maintained responding depending on food palatability
Suzanne M Droste1, Samantha K Saland, Emily K Schlitter
1Department of Psychology, Florida State University, Tallahassee, FL 32306, USA. rodefer@neuro.fsu.edu
Pharmacology, Biochemistry, and Behavior
|March 25, 2010
Summary
CB(1) receptor antagonists like AM 251 selectively reduce motivation for palatable foods. This study shows AM 251 decreased rat responding for chocolate, but not grain, reinforcing its role in appetite control.
Area of Science:
- Neuroscience
- Behavioral Pharmacology
- Addiction Research
Background:
- Cannabinoid CB(1)-receptor antagonists influence feeding behavior and motivation.
- Rimonabant, a CB(1) antagonist, was removed from trials, necessitating research on alternatives like AM 251.
- Understanding selective effects on palatable food motivation is crucial for therapeutic development.
Purpose of the Study:
- To investigate the effects of the CB(1) receptor antagonist AM 251 on motivated feeding behavior in rats.
- To determine if AM 251 selectively affects motivation for palatable versus standard food rewards.
Main Methods:
- Rats were trained to work for grain or chocolate pellets under progressive-ratio schedules.
- Rats received acute injections of AM 251 (0.3-3.0 mg/kg) or vehicle.
- Behavioral responses, including break points, were measured to assess motivation.
Main Results:
- AM 251 administration resulted in dose-dependent reductions in responding for chocolate-flavored pellets.
- Reductions in deliveries and break points were observed for palatable food.
- No significant effects on responding for grain pellets were found.
Conclusions:
- CB(1) receptor antagonism selectively diminishes motivation to obtain highly palatable foods.
- AM 251 demonstrates potential as a tool to modulate appetite for rewarding food items.
- These findings support further investigation of CB(1) antagonists for appetite regulation.
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