BACKGROUND: Little is known about changes in brain activity with pharmacological modulation of hyperalgesia. Therefore, we sought to investigate the cerebral processing of hyperalgesia and acute pain using functional magnetic resonance imaging (fMRI) and pharmacological modulation with cyclooxygenase (COX) inhibitors. METHODS: As an experimental model, we used UVB-induced mechanical hyperalgesia. In a double-blind, placebo-controlled, randomized study, acetylsalicylic acid (ASA) and parecoxib were administered to 14 healthy volunteers. Corresponding brain activity changes were assessed using fMRI. RESULTS: Psychophysically, parecoxib showed both analgesic and antihyperalgesia effects, whereas ASA had only antihyperalgesic effects in the experimental model. Analgesic effects were found in primary (S1) and secondary (S2) somatosensory cortices and anterior parts of the anterior cingulate cortex (ACC). In contrast, antihyperalgesic effects were mainly detected in S1, parietal association cortices, and the ACC. CONCLUSION: This study provides new evidence for the involvement of COX inhibitors in modulating the cerebral activity associated with acute pain and hyperalgesia. Our results hint at a differential modulation of brain areas under either analgesia or antihyperalgesia.
RCT Entities:
BACKGROUND: Little is known about changes in brain activity with pharmacological modulation of hyperalgesia. Therefore, we sought to investigate the cerebral processing of hyperalgesia and acute pain using functional magnetic resonance imaging (fMRI) and pharmacological modulation with cyclooxygenase (COX) inhibitors. METHODS: As an experimental model, we used UVB-induced mechanical hyperalgesia. In a double-blind, placebo-controlled, randomized study, acetylsalicylic acid (ASA) and parecoxib were administered to 14 healthy volunteers. Corresponding brain activity changes were assessed using fMRI. RESULTS: Psychophysically, parecoxib showed both analgesic and antihyperalgesia effects, whereas ASA had only antihyperalgesic effects in the experimental model. Analgesic effects were found in primary (S1) and secondary (S2) somatosensory cortices and anterior parts of the anterior cingulate cortex (ACC). In contrast, antihyperalgesic effects were mainly detected in S1, parietal association cortices, and the ACC. CONCLUSION: This study provides new evidence for the involvement of COX inhibitors in modulating the cerebral activity associated with acute pain and hyperalgesia. Our results hint at a differential modulation of brain areas under either analgesia or antihyperalgesia.
Authors: Wolfgang Koppert; Andreas Wehrfritz; Nicole Körber; Reinhard Sittl; Sven Albrecht; Jürgen Schüttler; Martin Schmelz Journal: Pain Date: 2004-03 Impact factor: 6.961
Authors: Christian Maihöfner; Martin Schmelz; Clemens Forster; Bernhard Neundörfer; Hermann O Handwerker Journal: Eur J Neurosci Date: 2004-06 Impact factor: 3.386