Opioids Inhibit Lateral Amygdala Pyramidal Neurons by Enhancing a Dendritic Potassium Current

J Neurosci. 2004 Mar 24;24(12):3031-9. doi: 10.1523/JNEUROSCI.4496-03.2004.

Abstract

Pyramidal neurons in the lateral amygdala discharge trains of action potentials that show marked spike frequency adaptation, which is primarily mediated by activation of a slow calcium-activated potassium current. We show here that these neurons also express an alpha-dendrotoxin- and tityustoxin-Kalpha-sensitive voltage-dependent potassium current that plays a key role in the control of spike discharge frequency. This current is selectively targeted to the primary apical dendrite of these neurons. Activation of micro-opioid receptors by application of morphine or d-Ala(2)-N-Me-Phe(4)-Glycol(5)-enkephalin (DAMGO) potentiates spike frequency adaptation by enhancing the alpha-dendrotoxin-sensitive potassium current. The effects of micro-opioid agonists on spike frequency adaptation were blocked by inhibiting G-proteins with N-ethylmaleimide (NEM) and by blocking phospholipase A(2). Application of arachidonic acid mimicked the actions of DAMGO or morphine. These results show that micro-opioid receptor activation enhances spike frequency adaptation in lateral amygdala neurons by modulating a voltage-dependent potassium channel containing Kv1.2 subunits, through activation of the phospholipase A(2)-arachidonic acid-lipoxygenases cascade.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Action Potentials / drug effects
  • Action Potentials / physiology
  • Amygdala / cytology
  • Amygdala / drug effects
  • Amygdala / physiology*
  • Animals
  • Dendrites / drug effects
  • Dendrites / metabolism*
  • In Vitro Techniques
  • Narcotics / pharmacology*
  • Neurotransmitter Agents / pharmacology
  • Patch-Clamp Techniques
  • Potassium Channel Blockers / pharmacology
  • Potassium Channels / drug effects
  • Potassium Channels / metabolism*
  • Pyramidal Cells / drug effects
  • Pyramidal Cells / metabolism
  • Pyramidal Cells / physiology*
  • Rats
  • Rats, Wistar
  • Receptors, Opioid, mu / drug effects
  • Receptors, Opioid, mu / metabolism

Substances

  • Narcotics
  • Neurotransmitter Agents
  • Potassium Channel Blockers
  • Potassium Channels
  • Receptors, Opioid, mu