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Changes in extracellular dopamine during cocaine self-administration in squirrel monkeys
Heather L Kimmel1, Brett C Ginsburg, Leonard L Howell
1Yerkes National Primate Research Center, Emory University, Atlanta, Georgia 30322, USA. Heathr.Kimmel@emory.edu
Synapse (New York, N.Y.)
|March 15, 2005
Summary
Environmental context influences cocaine's effect on dopamine. The study found that the setting of cocaine self-administration, not just the drug, alters dopamine release in squirrel monkeys.
Area of Science:
- Neuroscience
- Behavioral Neuroscience
- Addiction Research
Background:
- Environmental cues are linked to drug craving and relapse in cocaine addiction.
- Cocaine-associated cues can trigger drug-seeking behavior and alter dopamine levels.
Purpose of the Study:
- To investigate how the environmental context of cocaine self-administration affects dopamine levels in the caudate nucleus.
- To compare dopamine responses during active cocaine self-administration versus passive cocaine infusion.
Main Methods:
- Squirrel monkeys self-administered cocaine under a second-order schedule.
- Dopamine levels in the caudate nucleus were measured during active cocaine/saline self-administration and passive cocaine infusions.
- Behavioral task performance and dopamine release were monitored.
Main Results:
- Cocaine administration elevated dopamine levels approximately twofold.
- The peak dopamine response was shifted earlier in animals actively self-administering cocaine compared to those passively receiving it.
- Dopamine levels declined during cocaine self-administration sessions, even with continued drug intake, and fell below baseline during saline sessions.
Conclusions:
- The environmental context significantly modulates cocaine-induced dopamine elevations.
- Active drug-seeking behavior within a specific environment influences the neurochemical response to cocaine.
- Findings suggest environmental cues play a critical role in the neurobiology of cocaine addiction and relapse.