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Conditioned facilitation of brain reward function after repeated cocaine administration
Paul J Kenny1, George F Koob, Athina Markou
1Department of Neuropharmacology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
Behavioral Neuroscience
|October 23, 2003
Summary
Cocaine use lowers brain reward thresholds. Conditioned stimuli associated with cocaine also lowered reward thresholds in rats, demonstrating a learned facilitation of brain reward function.
Area of Science:
- Neuroscience
- Behavioral Pharmacology
- Reward System Research
Background:
- Cocaine acutely reduces brain reward thresholds, indicating enhanced brain reward function.
- Understanding how drug-associated cues influence reward pathways is crucial for addiction research.
Purpose of the Study:
- To investigate if stimuli predicting cocaine administration can lower intracranial self-stimulation (ICSS) thresholds.
- To determine if conditioned stimuli mimic the reward-facilitating effects of acute cocaine.
Main Methods:
- Rats underwent daily injections: 5 days saline, 20 days cocaine (10 mg/kg), 5 days saline.
- Intracranial self-stimulation (ICSS) thresholds were measured before and after injections.
- Behavioral responses to conditioned stimuli were assessed during the final saline phase.
Main Results:
- Cocaine significantly lowered ICSS thresholds throughout the 20-day administration period.
- No tolerance or sensitization to cocaine's effect on reward thresholds was observed.
- During the final saline phase, rats showed a conditioned lowering of ICSS thresholds.
Conclusions:
- Cocaine administration consistently lowers brain reward thresholds.
- Cocaine-predictive conditioned stimuli can induce a conditioned facilitation of brain reward function.
- These findings highlight the role of learning and conditioned cues in drug-induced reward alterations.