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Aspects of abstinence after morphine ingestion
L Rönnbäck1, P S Eriksson, J Zeuchner
1Institute of Neurobiology, University of Göteborg, Sweden.
Pharmacology, Biochemistry, and Behavior
|September 1, 1987
Summary
This study quantifies morphine physical dependence in rats using abstinence signs. Controlled diet and fluid intake revealed body weight loss and decreased appetite during withdrawal, with methadone partially blocking these effects.
Area of Science:
- Pharmacology
- Neuroscience
- Animal Models
Background:
- Assessing physical dependence on morphine is crucial for understanding opioid addiction.
- Previous methods for quantifying dependence have limitations.
Purpose of the Study:
- To validate a morphine intoxication method for studying physical dependence.
- To identify and quantify abstinence signs for dependence assessment.
- To control for diet and fluid intake during withdrawal studies.
Main Methods:
- Sprague-Dawley male rats were administered morphine orally.
- Physical dependence was assessed via abstinence symptoms during withdrawal and after naloxone administration.
- Diet and fluid intake were controlled throughout the experiment.
Main Results:
- Morphine withdrawal in rats led to decreased diet intake, body weight loss (anorexia), irritation, tremor, and motor excitation.
- Body weight loss during early withdrawal correlated with morphine dose.
- Methadone partially mitigated diet intake reduction and weight loss.
- Naloxone-induced withdrawal included motor excitation, cholinergic signs, weight loss, diarrhea, and reduced diet intake.
Conclusions:
- The controlled intoxication method effectively induces and allows for quantification of morphine physical dependence.
- Specific abstinence signs, such as body weight changes and reduced intake, are valuable for assessing dependence severity.
- Methadone exhibits partial antagonist properties in this model.
- Naloxone-precipitated withdrawal symptoms are dose-dependent and reflect physical dependence.