The effect of paracetamol on nociception and dynorphin A levels in the rat brain

M. Sandrini, P. Romualdi, A. Capobianco, G. Vitale, G. Morelli, L. A. Pini, S. Candeletti

Research output: Contribution to journalArticlepeer-review


Male Wistar rats were administered with naloxone (1 mg/kg i.p.) or MR 2266 (5 mg/kg i.p) 15 min before paracetamol (400 mg/kg i.p.) treatment and the pain threshold was evaluated. Rats were subjected to the hot-plate and formalin tests and immunoreactive dynorphin A (ir-dynorphin A) levels were measured in the hypothalamus, hippocampus, striatum, brainstem, frontal and parietal-temporal cortex by radioimmunoassay. Pretreatment with naloxone abolished paracetamol antinociceptive activity both in hot-plate and in the first phase, but not in the second phase of the formalin test, while MR 2266 pretreatment was able to antagonise paracetamol effect either in the hot-plate test or in both phases of the formalin test. Among different brain areas investigated paracetamol significantly decreased ir-dynorphin A levels only in the frontal cortex. MR 2266 but not naloxone reversed the decrease in ir-dynorphin A levels elicited by paracetamol. Paracetamol seems to exert its antinociceptive effect also through the opioidergic sistem modulating dynorphin release in the central nervous system (CNS) of the rat, as suggested by the decrease in the peptide levels.

Original languageEnglish
Pages (from-to)110-116
Number of pages7
Issue number2
Publication statusPublished - 2001

ASJC Scopus subject areas

  • Endocrinology
  • Clinical Neurology
  • Endocrinology, Diabetes and Metabolism
  • Cellular and Molecular Neuroscience
  • Neuroscience(all)
  • Biochemistry


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