The effect of dopaminergic modifiers on morphine-induced analgesia and respiratory depression.
The influences of the dopaminergic system on morphine-induced analgesia and respiratory depression were compared using modulators of dopaminergic activity. Blockade of dopaminergic receptors by haloperidol or pimozide produced a potentiation of morphine analgesia, while stimulation of dopaminergic activity by L-dopa methyl ester inhibited morphine analgesia. Morphine-induced depression of respiratory rate was potentiated by haloperidol and inhibited by pimozide or L-dopa methyl ester. These results suggest that the dopaminergic system plays a modulating role in morphine-induced analgesia, but not in morphine-induced respiratory depression.
D000701:Analgesics, Opioid; D000818:Animals; D004298:Dopamine / Q000502:physiology*; D004347:Drug Interactions; D006220:Haloperidol / Q000494:pharmacology; D007980:Levodopa / Q000494:pharmacology; D008297:Male; D051379:Mice; D009020:Morphine / Q000494:pharmacology*; D010868:Pimozide / Q000494:pharmacology; D011930:Reaction Time / Q000187:drug effects; D012119:Respiration / Q000187:drug effects*
D000701:Analgesics, Opioid; D010868:Pimozide; D007980:Levodopa; D009020:Morphine; D006220:Haloperidol; D004298:Dopamine