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Hypothalamic self-stimulation under the chronic morphine treatment in the rat
Research Communications in Chemical Pathology and Pharmacology
|April 1, 1977
Summary
Chronic morphine administration initially depressed, then activated, self-stimulation reward behavior in animals. This suggests a neurophysiological mechanism underlying morphine addiction.
Area of Science:
- Neuroscience
- Pharmacology
- Behavioral Science
Background:
- Morphine is a potent opioid analgesic with a high potential for abuse.
- Understanding the neurobiological underpinnings of morphine's effects on reward pathways is crucial for addiction research.
Purpose of the Study:
- To investigate the influence of chronic morphine administration on self-stimulation (SS) behavior.
- To explore the neurophysiological mechanisms potentially contributing to morphine abuse and addiction.
Main Methods:
- Chronic morphine administration over 15 days (30 injections).
- Dose escalation from 20 to 20 mg/kg per injection.
- Assessment of self-stimulation (SS) behavior as a measure of reward pathway activation.
Main Results:
- Initial morphine doses exhibited a variable depressive effect on SS behavior.
- Subsequent injections led to a significant activation of SS behavior.
- Observed activation of reward behavior suggests a biphasic effect of chronic morphine.
Conclusions:
- Chronic morphine administration can alter reward system sensitivity.
- The activation of reward behavior by later morphine doses may represent a key neurophysiological mechanism in the development of morphine abuse and addiction.
- These findings contribute to understanding the neurobiology of opioid addiction.