The effect of dopaminergic modifiers on morphine-induced analgesia and respiratory depression

Eur J Pharmacol. 1979 Feb 15;54(1-2):61-8. doi: 10.1016/0014-2999(79)90408-4.


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.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Analgesics, Opioid*
  • Animals
  • Dopamine / physiology*
  • Drug Interactions
  • Haloperidol / pharmacology
  • Levodopa / pharmacology
  • Male
  • Mice
  • Morphine / pharmacology*
  • Pimozide / pharmacology
  • Reaction Time / drug effects
  • Respiration / drug effects*


  • Analgesics, Opioid
  • Pimozide
  • Levodopa
  • Morphine
  • Haloperidol
  • Dopamine