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The effects of analgesics on central processing of tonic pain: A cross-over placebo controlled study

Dina Lelic1, Tine M Hansen2, Esben B Mark3

  • 1Mech-Sense, Department of Gastroenterology & Hepatology, Aalborg University Hospital, Aalborg, Denmark.

Neuropharmacology
|June 27, 2017
PubMed
Abstract

Insights

Oxycodone and venlafaxine (SNRI) reduce pain through distinct brain mechanisms. Oxycodone affects delta and theta brainwaves in the insula and frontal gyrus, while venlafaxine impacts alpha waves during pain.

Area of Science:

  • Neuroscience
  • Pain Management
  • Pharmacology

Background:

  • Opioids and serotonin-norepinephrine reuptake inhibitors (SNRIs) are used for pain relief.
  • Central mechanisms of analgesia for these drugs are not fully understood.
  • This study examined brain activity changes induced by oxycodone and venlafaxine.

Purpose of the Study:

  • To investigate the effects of oxycodone and venlafaxine on brain activity during rest and tonic pain.
  • To elucidate the central mechanisms of analgesia for opioids and SNRIs.

Main Methods:

  • A randomized, cross-over, double-blind study involving 20 healthy males.
  • Electroencephalogram (EEG) recorded at rest and during tonic pain (cold water immersion).
  • Analysis of spectral indices and source localization (sLORETA) across multiple frequency bands (delta, theta, alpha, beta).

Main Results:

  • Both oxycodone and venlafaxine reduced subjective pain scores.
  • Neither drug altered resting EEG spectral indices or brain sources.
  • During tonic pain, venlafaxine decreased alpha band EEG activity.
  • Oxycodone decreased delta and theta band EEG activity and associated brain source activity, particularly in the insula and inferior frontal gyrus.

Conclusions:

  • Oxycodone's pain inhibition is linked to reduced activity in the insula and inferior frontal gyrus.
  • Venlafaxine's pain inhibition is associated with decreased alpha band activity.
  • Distinct neural pathways mediate analgesia for opioids and SNRIs.
Keywords:
Brain source localizationEEGLORETAOpioidSNRI

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