Presynaptic Actions of Opioids

  • Steven W. Johnson
  • R. Alan North


Opioids bind to μ, δ, and κ receptor subtypes, and the recent discovery of selective agonists and antagonists at these receptors has permitted their pharmacological characterization (Kosterlitz, 1991). Electrophysiologic technique have advantages over other methodologies because opioid effects can be studied at the level of the single neuron, yet with many or all of the synaptic connections intact. Results of electrophysiologic experiments suggest that opioids have a modulatory role in synaptic transmission, rather than acting as conventional “fast” neurotransmitters. Inhibition of neurotransmitter release is a recurring theme in investigations of the pharmacodynamics of opioids at all three receptor subtypes.


Ventral Tegmental Area Action Potential Duration Dopamine Neuron Locus Ceruleus Kappa Opioid Receptor 
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© Birkhäuser Boston 1993

Authors and Affiliations

  • Steven W. Johnson
  • R. Alan North

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