Evidence of a central antinociceptive effect of paracetamol involving spinal 5HT3 receptors

Neuroreport. 1995 Jul 31;6(11):1546-8. doi: 10.1097/00001756-199507310-00020.


This study was carried out to determine both the effect of systemic paracetamol on the C-fibre evoked reflex activity, a test sensitive to centrally acting analgesic drugs, and the influence of an intrathecally administered 5HT3 receptor antagonist, tropisetron. Paracetamol (200, 300, 400 mg kg-1, i.v.) dose-dependently decreased (maximal effects -60 +/- 8%) the C-evoked responses for a duration of 90 min (for the lowest dose). This effect was totally suppressed by tropisetron (1 microgram, i.t.). These data confirm previous studies suggesting a central effect of this drug and demonstrate the involvement of a spinal 5HT3 mediated serotonergic mechanism.

MeSH terms

  • Acetaminophen / pharmacology*
  • Analgesics, Non-Narcotic / pharmacology*
  • Animals
  • Evaluation Studies as Topic
  • Indoles / pharmacology
  • Male
  • Nerve Fibers / drug effects*
  • Rats
  • Rats, Sprague-Dawley
  • Reflex / drug effects*
  • Serotonin Antagonists / pharmacology*
  • Spinal Cord / drug effects*
  • Tropisetron


  • Analgesics, Non-Narcotic
  • Indoles
  • Serotonin Antagonists
  • Acetaminophen
  • Tropisetron