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Updated: Jul 14, 2026
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A General Method for Evaluating Incubation of Sucrose Craving in Rats
Published on: November 4, 2011
Incentive sensitization by previous amphetamine exposure: increased cue-triggered "wanting" for sucrose reward
1Department of Psychology, University of Michigan, Ann Arbor, Michigan 48109, USA. wyvell@umich.edu
Summary
Amphetamine sensitization enhances reward cue salience, leading to excessive reward seeking even when drug-free. This supports the incentive-sensitization theory of addiction.
Area of Science:
- Neuroscience
- Behavioral Pharmacology
Background:
- Previous research shows amphetamine microinjection in the nucleus accumbens triggers excessive reward pursuit.
- Amphetamine sensitization is a known phenomenon in behavioral pharmacology.
Purpose of the Study:
- To investigate if amphetamine sensitization alone, without acute drug administration, enhances Pavlovian reward cue-induced excessive instrumental pursuit.
- To determine if sensitization increases incentive salience of reward cues in a drug-free state.
Main Methods:
- Rats were trained to lever press for sucrose and associate auditory cues with sucrose.
- Amphetamine sensitization was induced via daily injections; controls received saline.
- Testing involved microinjections into the nucleus accumbens (vehicle or amphetamine) and assessing lever pressing during cue presentations under extinction.
Main Results:
- Sensitized rats showed significantly greater cue-triggered lever pressing (100% increase) compared to controls when tested drug-free.
- Amphetamine microinjection was required in control rats to match the sensitized rats' response.
- In sensitized rats, amphetamine microinjection synergistically increased intrusive behaviors, interfering with goal-directed actions.
Conclusions:
- Amphetamine sensitization enhances the incentive salience of associated reward cues, promoting excessive reward "wanting" even in a drug-free state.
- These findings support the incentive-sensitization theory's explanation for addiction-related behaviors.
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