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Assessment of Morphine-induced Hyperalgesia and Analgesic Tolerance in Mice Using Thermal and Mechanical Nociceptive Modalities
Published on: July 29, 2014
Tolerance development to morphine-induced alterations of immune status
J P West1, D T Lysle, L A Dykstra
1University of North Carolina at Chapel Hill 27599-3270, USA.
Drug and Alcohol Dependence
|July 4, 1997
Summary
Chronic morphine consumption in rats leads to tolerance in natural killer (NK) cell activity but not other immune responses. Rats also showed tolerance to pain relief and signs of dependence.
Area of Science:
- Immunology
- Pharmacology
- Neuroscience
Background:
- Opioid drugs like morphine can affect immune function.
- Understanding the development of tolerance to morphine's effects on the immune system is crucial.
Purpose of the Study:
- To investigate the development of tolerance to morphine's effects on various immune measures in rats.
- To assess whether chronic morphine consumption alters the immune response to acute morphine administration.
Main Methods:
- Lewis rats were chronically administered morphine solutions via drinking water.
- Immune responses, including natural killer (NK) cell activity, T- and B-cell proliferation, and gamma-interferon (gamma-IFN) production, were measured.
- Rats received acute morphine injections before sacrifice, and antinociceptive effects and physical dependence were also assessed.
Main Results:
- Acute morphine injection suppressed immune activity in control rats.
- Rats with chronic morphine exposure showed tolerance to morphine's suppressive effects on NK cell activity.
- Tolerance was not observed for T- and B-cell proliferation or gamma-IFN production; these remained suppressed.
- Chronic morphine consumption also led to tolerance in antinociceptive effects and physical dependence.
Conclusions:
- Chronic morphine exposure induces tolerance to its immunosuppressive effects on NK cells, but not other immune parameters.
- The findings highlight differential tolerance development to morphine's immunomodulatory actions.
- Morphine dependence and tolerance to analgesic effects were also confirmed in these rats.
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