Effects of Parecoxib and Fentanyl on nociception-induced cortical activity.
BACKGROUND
Analgesics, including opioids and non-steroid anti-inflammatory drugs reduce postoperative pain. However, little is known about the quantitative effects of these drugs on cortical activity induced by nociceptive stimulation. The aim of the present study was to determine the neural activity in response to a nociceptive stimulus and to investigate the effects of fentanyl (an opioid agonist) and parecoxib (a selective cyclooxygenase-2 inhibitor) on this nociception-induced cortical activity evoked by tail pinch. Extracellular recordings (electroencephalogram and multi-unit signals) were performed in the area of the anterior cingulate cortex while intracellular recordings were made in the primary somatosensory cortex. The effects of parecoxib and fentanyl on induced cortical activity were compared.


RESULTS
Peripheral nociceptive stimulation in anesthetized rats produced an immediate electroencephalogram (EEG) desynchronization resembling the cortical arousal (low-amplitude, fast-wave activity), while the membrane potential switched into a persistent depolarization state. The induced cortical activity was abolished by fentanyl, and the fentanyl's effect was reversed by the opioid receptor antagonist, naloxone. Parecoxib, on the other hand, did not significantly affect the neural activity.


CONCLUSIONS
Cortical activity was modulated by nociceptive stimulation in anesthetized rats. Fentanyl showed a strong inhibitory effect on the nociceptive-stimulus induced cortical activity while parecoxib had no significant effect.
Peng
Yuan-Zhi
YZ
Department of Anesthesiology, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200092, China.
Li
Xiao-Xi
XX
Wang
Ying-Wei
YW
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000701:Analgesics, Opioid / Q000494:pharmacology; D000818:Animals; D001143:Arousal / Q000187:drug effects / Q000502:physiology; D002540:Cerebral Cortex / Q000187:drug effects* / Q000502:physiology; D052246:Cyclooxygenase 2 Inhibitors / Q000494:pharmacology; D004569:Electroencephalography; D004594:Electrophysiology; D005071:Evoked Potentials / Q000187:drug effects / Q000502:physiology; D005283:Fentanyl / Q000494:pharmacology*; D006179:Gyrus Cinguli / Q000187:drug effects / Q000502:physiology; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D007555:Isoxazoles / Q000494:pharmacology*; D009474:Neurons / Q000187:drug effects* / Q000502:physiology; D009619:Nociceptors / Q000187:drug effects* / Q000502:physiology; D010146:Pain / Q000188:drug therapy* / Q000503:physiopathology; D010147:Pain Measurement; D051381:Rats; D017207:Rats, Sprague-Dawley; D012119:Respiration / Q000187:drug effects; D013003:Somatosensory Cortex / Q000187:drug effects / Q000502:physiology
D000701:Analgesics, Opioid; D052246:Cyclooxygenase 2 Inhibitors; D007555:Isoxazoles; C409945:parecoxib; D005283:Fentanyl