Electrophysiological effects of dermorphin on locus coeruleus neurons of rat

T. H. Chiu, Tsung-Yu Chen, C. L. Ho, S. T. Chiang

Research output: Contribution to journalArticle

10 Scopus citations

Abstract

Intracellular recording was used to study the effects of dermorphin on neurons of the locus coeruleus in the rat, in a totally submerged brain slice preparation. Dermorphin caused the inhibition of spontaneous firing of all neurons of the locus coeruleus tested, with an IC50 of 7 nM. Based on the inhibition of spontaneous firing rate, dermorphin was 16.5 times more potent than morphine. Larger concentrations of dermorphin (30-100 nM) further hyperpolarized the neurons of the locus coeruleus and simultaneously caused a reduction in input resistance. These effects were antagonized by naloxone, with a dissociation equilibrium constant of 0.8 nM. The hyperpolarization of neurons of the locus coeruleus, caused by dermorphin, was reversed at a membrane potential of -112mV in this preparation. Furthermore, this hyperpolarization was blocked by cesium chloride and barium chloride. Thus, these data suggest that dermorphin binds to μ-opioid receptors on the cell membrane of neurons of the locus coeruleus. This leads to opening of the inward-going rectification potassium channels, resulting in the observed hyperpolarization of the membrane.

Original languageEnglish (US)
Pages (from-to)747-755
Number of pages9
JournalNeuropharmacology
Volume29
Issue number8
DOIs
StatePublished - 1990
Externally publishedYes

Keywords

  • brain slices
  • dermorphin
  • intracellular recording
  • locus coeruleus

ASJC Scopus subject areas

  • Cellular and Molecular Neuroscience
  • Drug Discovery
  • Pharmacology

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