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Cocaine-induced locomotor activity in rats
1National Institute On Drug Abuse, Addiction Research Center, Baltimore, MD.
Pharmacology, Biochemistry, and Behavior
|July 1, 1991
Summary
Chronic cocaine exposure in rats alters locomotor activity patterns, showing both sensitization and desensitization. These changes suggest complex adaptations in the central nervous system to repeated drug administration.
Area of Science:
- Neuroscience
- Pharmacology
- Behavioral Science
Background:
- Cocaine is a potent psychostimulant with significant abuse potential.
- Understanding the neurobiological effects of chronic cocaine use is crucial for addiction research.
Purpose of the Study:
- To investigate the effects of chronic cocaine administration on locomotor activity in rats.
- To examine potential sensitization and desensitization phenomena following repeated cocaine exposure.
Main Methods:
- Rats received daily subcutaneous (SC) or intraperitoneal (IP) injections of cocaine (20 mg/kg) or saline for 15 consecutive days.
- Locomotor activity was assessed after the first (acute) and 15th (chronic) injections.
Main Results:
- Total locomotor activity (AUC) was comparable between acute and chronic cocaine administration.
- Peak locomotor activity occurred earlier and was significantly higher after chronic cocaine exposure, indicating sensitization.
- Late-session activity was reduced following chronic SC cocaine, suggesting desensitization.
Conclusions:
- Chronic cocaine administration induces complex changes in locomotor activity, including both sensitization and desensitization.
- These findings highlight the dynamic neuroadaptations occurring with repeated stimulant exposure.
- Altered pharmacokinetics may contribute to the observed changes in locomotor activity.