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Cocaine sensitization in the mouse using a cumulative dosing regime
1Psychobiology Section, National Institute on Drug Abuse, IRP, Baltimore, Maryland, USA. elizabeth.elliot@adelaide.edu.au
Behavioural Pharmacology
|October 24, 2002
Summary
This study shows that repeated exposure to cocaine, especially with handling, significantly increases locomotor stimulant effects in mice. This cocaine sensitization is context-dependent and long-lasting.
Area of Science:
- Neuroscience
- Pharmacology
- Behavioral Science
Background:
- Rodent models often use high-dose cocaine pretreatment for sensitization studies.
- Understanding cocaine sensitization mechanisms is crucial for addiction research.
Purpose of the Study:
- Investigate the rate and extent of cocaine sensitization using multiple doses.
- Examine context-dependent sensitization to cocaine's locomotor-stimulant effects.
Main Methods:
- Eight groups of mice received different cocaine (5-40 mg/kg) or saline pretreatments over 4 days.
- Locomotor activity was tested on day 5 using cumulative cocaine doses.
- Sensitization was re-tested at 10-day intervals.
Main Results:
- All groups developed context-dependent sensitization to cocaine's locomotor effects.
- Sensitization peaked after five cumulative dosing sessions.
- Frequency of dosing and handling influenced sensitization rate and cocaine's potency/efficacy.
- Sensitization persisted despite a 5-day extinction procedure.
Conclusions:
- Cumulative cocaine dosing combined with handling induces robust, context-dependent sensitization.
- Sensitization is long-lasting and not solely due to cocaine exposure.
- Handling and environmental context are critical factors in cocaine sensitization.