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Behavioral dependence produced by continuous phencyclidine infusion in rhesus monkeys
The Journal of Pharmacology and Experimental Therapeutics
|August 1, 1984
Summary
Continuous phencyclidine (PCP) infusion in monkeys increased operant responding. Withdrawal from PCP markedly suppressed behavior, indicating dependence. Repeated withdrawal effects diminished, requiring higher doses for disruption.
Area of Science:
- Neuroscience
- Behavioral Pharmacology
Background:
- Phencyclidine (PCP) is a dissociative drug with known psychoactive effects.
- Understanding PCP's impact on behavior and dependence is crucial for public health and clinical management.
Purpose of the Study:
- To investigate the effects of continuous phencyclidine (PCP) infusion and subsequent withdrawal on operant behavior in rhesus monkeys.
- To assess the development of behavioral dependence and withdrawal symptoms associated with chronic PCP exposure.
Main Methods:
- Rhesus monkeys were trained on a fixed-ratio 100 schedule for food reinforcement.
- Continuous intravenous infusion of PCP (0.05 mg/kg/hr) or saline was administered.
- Operant responding, withdrawal signs, and the effects of acute PCP or naloxone administration were monitored.
Main Results:
- Chronic PCP infusion increased operant responding rates compared to saline controls.
- PCP withdrawal, induced by saline substitution, caused marked suppression of responding and mild withdrawal signs (tremors, hyperactivity, aggression).
- Withdrawal effects diminished with repeated cycles, and acute PCP reversed withdrawal-induced disruption, while naloxone had no effect.
Conclusions:
- Operant behavior is significantly disrupted during PCP withdrawal, serving as evidence of behavioral dependence.
- PCP dependence does not appear to be opioid-mediated, as indicated by the lack of response to naloxone.
- The study highlights the potential for developing behavioral dependence with chronic PCP use and the need for further research into its mechanisms.