μ-Opioid receptor-independent fashion of the suppression of sodium currents by μ-opioid analgesics in thalamic neurons

Keisuke Hashimoto, Taku Amano, Akiko Kasakura, George R. Uhl, Ichiro Sora, Norio Sakai, Naoko Kuzumaki, Tsutomu Suzuki, Minoru Narita

Research output: Contribution to journalArticlepeer-review

Abstract

Most reports in the literature have shown that the effects of opioid analgesics are primarily mediated by μ-opioid receptor (MOR), whereas other potential targets of opioid analgesics have not been thoroughly characterized. In this study, we found that extracellular application of morphine, fentanyl or oxycodone, which are all considered to be MOR agonists, at relatively high concentrations, but not endogenous μ-opioid peptides, produced a concentration-dependent suppression of sodium currents in cultured thalamic neurons. These effects of opioids were not affected by either a MOR antagonist naloxone or a deletion of MOR gene. Among these opioids, fentanyl strongly suppressed sodium currents to the same degree as lidocaine, and both morphine and oxycodone slightly but significantly reduced sodium currents when they were present extracellularly. In contrast, the intracellular application of morphine, but not oxycodone, fentanyl or lidocaine, reduced sodium currents. These results suggest that morphine, fentanyl and oxycodone each produce the MOR-independent suppression of sodium currents by distinct mechanisms in thalamic neurons.

Original languageEnglish (US)
Pages (from-to)62-67
Number of pages6
JournalNeuroscience Letters
Volume453
Issue number1
DOIs
StatePublished - Mar 27 2009
Externally publishedYes

Keywords

  • Fentanyl
  • Lidocaine
  • Morphine
  • Oxycodone
  • Voltage-gated sodium channels

ASJC Scopus subject areas

  • Neuroscience(all)

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