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[Changes in stimulation analgesia during chronic morphine administration]
Farmakologiia I Toksikologiia
|July 1, 1985
Summary
Repeated morphine administration in rats induced tolerance to stimulation analgesia (SA), while periaqueductal gray matter (PGM) stimulation alone did not. Naloxone partially blocked SA in controls but not in morphine-treated rats.
Area of Science:
- Neuroscience
- Pharmacology
- Pain Research
Background:
- Repeated morphine administration can lead to the development of tolerance.
- Stimulation analgesia (SA) is a pain-modulating mechanism.
- The periaqueductal gray matter (PGM) is a key area involved in pain modulation.
Purpose of the Study:
- To investigate the development of tolerance to stimulation analgesia (SA) following repeated morphine administration in rats.
- To examine the role of the periaqueductal gray matter (PGM) in morphine-induced tolerance to SA.
- To assess the effect of naloxone on SA in both control and morphine-treated rats.
Main Methods:
- Rat experiments involving repeated morphine administration.
- Stimulation of the periaqueductal gray matter (PGM) to induce analgesia.
- Administration of naloxone to assess its antagonistic effects.
Main Results:
- Repeated morphine administration produced tolerance to SA.
- PGM stimulation alone in control rats did not produce tolerance.
- Naloxone partially antagonized SA in control rats.
- Naloxone did not affect the antinociceptive action of PGM stimulation in morphine-treated rats.
Conclusions:
- Repeated morphine administration induces tolerance to stimulation analgesia (SA) in rats.
- The periaqueductal gray matter (PGM) is involved in the development of tolerance to SA.
- Naloxone's effect on SA is dependent on prior morphine exposure.