An attempt to correlated analgesia to changes in brain neuromediators in rats.

The analgesic activity of delta9THC, morphine and sodium salicylate was studied concomitantly with changes in brain stem levels of 5HT, 5HIAA, DA and NA. The results show that a correlation exists between analgesia and changes in the serotonergic system of the brain stem. Furthermore morphine sulfate was found to increase the DA concentration of the brain stem while delta9THC increased NA levels. We conclude that serotonergic system may be of major importance in analgesia while simultaneous changes in this system and/or the DA and NA systems may lead to a more pronounced analgesic activity.