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Opioid-like analgesia in defeated mice
Science (New York, N.Y.)
|March 19, 1982
Summary
Stress-induced defeat in mice activates endogenous opioid systems, leading to analgesia (pain reduction). This pain relief is blocked by opiate antagonists and is less effective in morphine-tolerant mice.
Area of Science:
- Neuroscience
- Behavioral Science
- Pain Research
Background:
- Social stress, such as repeated attacks, can induce physiological changes in animals.
- Analgesia, or pain relief, can be modulated by stress and endogenous opioid systems.
Purpose of the Study:
- To investigate the analgesic effects of social defeat stress in mice.
- To determine the role of endogenous opioid systems in stress-induced analgesia.
Main Methods:
- Mice were subjected to repeated social defeat by dominant aggressors.
- Nociception was assessed using a radiant heat tail-flick test.
- The effects of centrally acting opiate antagonists and morphine tolerance were examined.
Main Results:
- Repeated social defeat led to decreased nociception (analgesia) in mice.
- This analgesia was antagonized by centrally acting opiate antagonists.
- Morphine-tolerant mice and a low-response strain (CXBK) exhibited reduced analgesia following defeat.
Conclusions:
- Social defeat stress activates endogenous opioid-mediated analgesic mechanisms.
- These findings highlight the significant role of endogenous opioids in mediating the body's response to biologically relevant stressors like social defeat.