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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
Effects of different spinal morphine doses in rats
Neuzimar de Souza Freire Silva1, Rioko Kimiko Sakata, Adriana Machado Issy
1Dor e Terapia Intensiva da Universidade Federal de São Paulo (UNIFESP), São Paulo, SP.
Revista Brasileira De Anestesiologia
|May 28, 2009
Summary
Spinal morphine provides pain relief but causes side effects. Even low doses (below 1 microgram) in rats resulted in short-term analgesia and adverse effects.
Area of Science:
- Pharmacology
- Neuroscience
- Pain Management
Background:
- Spinal morphine is effective for pain relief.
- Its use is associated with various side effects.
- Optimizing spinal morphine dosage is crucial for balancing efficacy and safety.
Purpose of the Study:
- To investigate the effects of different doses of spinal morphine.
- To evaluate the dose-dependent analgesic effects of spinal morphine.
- To identify the side effects associated with varying spinal morphine doses.
Main Methods:
- Rats received spinal catheterization via cisterna magna.
- Five groups were administered saline or varying doses of morphine (0.1, 0.3, 0.5, 1 microg).
- Analgesic response was measured using the tail immersion test at multiple time points post-injection.
Main Results:
- Morphine administration produced analgesia compared to controls.
- Observed side effects included paw weakness, agitation, tremors, pruritus, reduced diuresis, sedation, and respiratory changes.
- The incidence and duration of side effects generally increased with higher morphine doses.
Conclusions:
- Spinal morphine doses below 1 microgram induced short-lasting analgesia in rats.
- All tested doses of spinal morphine were associated with dose-dependent side effects.
- Further research is needed to determine optimal spinal morphine dosing strategies.
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