title: Prostaglandins and opioids.
abstract: In guinea-pig small intestine, rat brain in vitro and neuroblastomaXglioma hybrid cells, opioids specifically inhibit the action of E prostaglandins. In the whole rat, E prostaglandins, administered centrally, antagonize the antinociceptive action of morphine. E prostaglandins also antangonize the induction of opioid tolerant/dependence. In turn, tolerance/dependent preparations respond with added intensity to E prostaglandins. The antagonism between opioids and E prostaglandins does not occur at the opioid receptor; but, certainly in some preparations and probably in others, this antagonism occurs at the coupling or catalytic unit of a neuronal adenylate cyclase that opioids inhibit and E prostaglandins stimulate. The proposition that antagonism of E prostaglandin at appropriate neurons in the brain is part of the natural mechanism of opioid analgesia remains possible, but unproven, and is worth continued investigation.
mesh_terms: D000700:Analgesics / Q000494:pharmacology*; D000818:Animals; D001921:Brain / Q000187:drug effects / Q000502:physiology; D002460:Cell Line; D004361:Drug Tolerance; D005071:Evoked Potentials / Q000187:drug effects; D006168:Guinea Pigs; D006801:Humans; D007421:Intestine, Small / Q000187:drug effects / Q000502:physiology; D009020:Morphine / Q000494:pharmacology*; D009119:Muscle Contraction / Q000187:drug effects; D011458:Prostaglandins E / Q000494:pharmacology*; D051381:Rats; D011957:Receptors, Opioid / Q000187:drug effects; D019966:Substance-Related Disorders
chemical_list: D000700:Analgesics; D011458:Prostaglandins E; D011957:Receptors, Opioid; D009020:Morphine