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Learned helplessness inducing foot shock can exacerbate morphine responsiveness
G C Abrahamsen1, H S Stock, B J Caldarone
1Department of Psychology, University at Albany: State University of New York 12222.
Physiology & Behavior
|August 1, 1993
Summary
Foot shock exposure altered morphine hypoalgesia. Reactivity to morphine increased when tested in the shock context, but not in a novel environment, suggesting conditioned fear influences pain perception.
Area of Science:
- Neuroscience
- Behavioral Neuroscience
- Psychopharmacology
Background:
- Inescapable foot shock can induce learned helplessness and affect nociception.
- Previous research indicates tail shock influences nociception and morphine reactivity.
- Understanding how stress impacts pain perception and opioid response is crucial.
Purpose of the Study:
- To investigate the effect of foot shock, a known inducer of learned helplessness, on subsequent morphine reactivity.
- To determine if the testing context influences the hypoalgesic response to morphine after foot shock exposure.
Main Methods:
- Rats were exposed to inescapable foot shock.
- Morphine-induced hypoalgesia was assessed using a 4 mg/kg dose over four consecutive days.
- Testing occurred in either a novel context or the original shock context.
Main Results:
- Foot shock did not affect morphine-induced hypoalgesia in a novel testing context (Experiment 1A).
- Morphine-induced hypoalgesia was significantly increased when testing occurred in the shock context (Experiment 1B).
- These findings were replicated and extended to explore the role of conditioned fear (Experiment 2).
Conclusions:
- Context-dependent effects of foot shock on morphine analgesia were observed.
- Conditioned fear, associated with the shock environment, may contribute to altered morphine reactivity.
- Stress-induced changes in pain perception are influenced by environmental cues and learned associations.