The effect of biogenic amine modifiers on morphine analgesia and its antagonism by naloxone.
The stimulation of dopaminergic receptors, inhibition of serotonin synthesis or blockade of muscarinic receptors by various modifiers led to inhibition of morphine analgesia in mice. Blockade of dopaminergic receptors or the increase in serotonergic or cholinergic activity resulted in the enhancement of morphine analgesia. Serotonergic and cholinergic systems are proposed as positive and the dopaminergic system as negative modulators of morphine analgesia. The modulation of naloxone antagonism was much more complicated than that of morphine analgesia and often the effect of biogenic amine modifiers on antagonism differed from that on analgesia. The fact than biogenic amine modifiers do not affect morphine analgesia and naloxone antagonism by a similar pattern suggests that interaction of narcotics and narcotic antagonists with analgesic receptors may not be exactly the same.
D000698:Analgesia; D000818:Animals; D001679:Biogenic Amines / Q000008:administration & dosage / Q000494:pharmacology*; D001923:Brain Chemistry / Q000187:drug effects; D004347:Drug Interactions; D007274:Injections, Intraperitoneal; D008297:Male; D051379:Mice; D009020:Morphine / Q000032:analysis / Q000037:antagonists & inhibitors*; D009270:Naloxone / Q000032:analysis / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D011930:Reaction Time / Q000187:drug effects
D001679:Biogenic Amines; D009270:Naloxone; D009020:Morphine