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Effects of Parecoxib and Fentanyl on nociception-induced cortical activity.

Peng YZ, Li XX, Wang YW - Mol Pain (2010)

Bottom Line: The effects of parecoxib and fentanyl on induced cortical activity were compared.Parecoxib, on the other hand, did not significantly affect the neural activity.Fentanyl showed a strong inhibitory effect on the nociceptive-stimulus induced cortical activity while parecoxib had no significant effect.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Anesthesiology, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200092, China.

ABSTRACT

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.

Conclusion: 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.

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The effects of parecoxib and fentanyl on MU (Multi-Unit) and Non-uniform index of MU recordings. A: Spike mean firing rate from MU recordings were not altered in the presence of nociceptive stimulation. B: The non-uniform index of MU was decreased when nociceptive stimulus was applied (control), indicating that the neuronal firing pattern was more uniform under nociceptive stimulation than during the resting state. Fentanyl partially inhibited this response while parecoxib had no effect. *P < 0.05, **P < 0.01, #P < 0.001.
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Figure 5: The effects of parecoxib and fentanyl on MU (Multi-Unit) and Non-uniform index of MU recordings. A: Spike mean firing rate from MU recordings were not altered in the presence of nociceptive stimulation. B: The non-uniform index of MU was decreased when nociceptive stimulus was applied (control), indicating that the neuronal firing pattern was more uniform under nociceptive stimulation than during the resting state. Fentanyl partially inhibited this response while parecoxib had no effect. *P < 0.05, **P < 0.01, #P < 0.001.

Mentions: Although the Down state was reduced or disappeared (Fig. 1), nociceptive stimulation did not influence the spike mean firing rate from MU recordings (Fig. 5A). However, the firing rate was reduced in some neurons (Fig. 1A and 1E; lower panel), and this inhibition was also observed in previous studies [14,15]. We therefore, further investigated spike firing rate by a Non-uniform index of spike frequency to evaluate effects of parecoxib and fentanyl. This measure showed that nociceptive stimulation decreased the "non-uniform index" in control (untreated) animals and that parecoxib did not inhibit this response; The response was partially inhibited, however by fentanyl and again, naloxone abolished the fentanyl effect (Fig. 5B).


Effects of Parecoxib and Fentanyl on nociception-induced cortical activity.

Peng YZ, Li XX, Wang YW - Mol Pain (2010)

The effects of parecoxib and fentanyl on MU (Multi-Unit) and Non-uniform index of MU recordings. A: Spike mean firing rate from MU recordings were not altered in the presence of nociceptive stimulation. B: The non-uniform index of MU was decreased when nociceptive stimulus was applied (control), indicating that the neuronal firing pattern was more uniform under nociceptive stimulation than during the resting state. Fentanyl partially inhibited this response while parecoxib had no effect. *P < 0.05, **P < 0.01, #P < 0.001.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2819047&req=5

Figure 5: The effects of parecoxib and fentanyl on MU (Multi-Unit) and Non-uniform index of MU recordings. A: Spike mean firing rate from MU recordings were not altered in the presence of nociceptive stimulation. B: The non-uniform index of MU was decreased when nociceptive stimulus was applied (control), indicating that the neuronal firing pattern was more uniform under nociceptive stimulation than during the resting state. Fentanyl partially inhibited this response while parecoxib had no effect. *P < 0.05, **P < 0.01, #P < 0.001.
Mentions: Although the Down state was reduced or disappeared (Fig. 1), nociceptive stimulation did not influence the spike mean firing rate from MU recordings (Fig. 5A). However, the firing rate was reduced in some neurons (Fig. 1A and 1E; lower panel), and this inhibition was also observed in previous studies [14,15]. We therefore, further investigated spike firing rate by a Non-uniform index of spike frequency to evaluate effects of parecoxib and fentanyl. This measure showed that nociceptive stimulation decreased the "non-uniform index" in control (untreated) animals and that parecoxib did not inhibit this response; The response was partially inhibited, however by fentanyl and again, naloxone abolished the fentanyl effect (Fig. 5B).

Bottom Line: The effects of parecoxib and fentanyl on induced cortical activity were compared.Parecoxib, on the other hand, did not significantly affect the neural activity.Fentanyl showed a strong inhibitory effect on the nociceptive-stimulus induced cortical activity while parecoxib had no significant effect.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Anesthesiology, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200092, China.

ABSTRACT

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.

Conclusion: 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.

Show MeSH
Related in: MedlinePlus