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Morphine deteriorates spatial memory in sodium salicylate treated rats
Mehdi Sadegh1, Yaghoub Fathollahi, Nasser Naghdi
1Department of Physiology, School of Medical Sciences, Tarbiat Modares University, PO Box 14115-111, Tehran, Iran.
European Journal of Pharmacology
|March 7, 2013
Summary
Chronic morphine and sodium salicylate treatments induce tolerance and cross-tolerance in pain relief. Salicylate may also alter brain mechanisms for spatial learning and memory, showing cross-sensitization to morphine.
Area of Science:
- Neuroscience
- Pharmacology
- Behavioral Science
Background:
- Opioid analgesics like morphine and non-steroidal anti-inflammatory drugs such as sodium salicylate are widely used for pain management.
- Understanding the development of tolerance and cross-tolerance is crucial for optimizing pain treatment strategies.
- Investigating the impact of chronic drug administration on cognitive functions, like spatial learning, is essential.
Purpose of the Study:
- To examine the development of tolerance and cross-tolerance to the anti-nociceptive effects of morphine and sodium salicylate.
- To assess the influence of chronic morphine and sodium salicylate administration on spatial learning and memory.
- To explore potential cross-sensitization between morphine and sodium salicylate in the context of learning.
Main Methods:
- Tolerance was induced via daily intraperitoneal injections of morphine sulfate (10 mg/kg for 7 days) or sodium salicylate (300 mg/kg for 6 days).
- Anti-nociceptive effects were measured using the tail flick (TF) and hot plate (HP) tests.
- Spatial learning and memory were assessed using the Morris water maze (MWM).
Main Results:
- Both morphine and sodium salicylate induced tolerance to their own anti-nociceptive effects.
- Cross-tolerance was observed: sodium salicylate-tolerant rats showed a reduced response to morphine, and morphine-tolerant rats showed a diminished response to sodium salicylate.
- While acute morphine impaired MWM performance, chronic administration of either drug did not affect MWM performance. However, morphine administration after chronic salicylate treatment impaired spatial memory recall.
Conclusions:
- Chronic administration of sodium salicylate leads to tolerance to morphine's anti-nociceptive effects, and vice versa, indicating significant cross-tolerance.
- Chronic salicylate treatment may induce lasting metaplastic changes in brain mechanisms underlying spatial learning and memory.
- These findings suggest a potential for cross-sensitization between chronic salicylate and morphine concerning cognitive functions.
