Articles: hyperalgesia.
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In this prospective, randomized, double-blind study, we verified the hypothesis that TEAS can alleviate remifentanil-induced hyperalgesia in patients undergoing thyroidectomy. ⋯ Preoperative TEAS can attenuate remifentanil-induced hyperalgesia in patients undergoing thyroidectomy.
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Ropivacaine is a local anesthetic widely used for regional anesthesia and epidural analgesia, but its relatively short duration limits its clinical use. A novel sustained release lipid formulation of ropivacaine has been recently developed to prolong its duration. We examined the epidural anti-hypersensitivity and preemptive effects of ropivacaine in mesylate injection and sustained release suspension forms in a rat model of neuropathy produced by peripheral nerve injury. ⋯ The single and multiple daily epidural injection of ropivacaine sustained release suspension further delayed the biological half-lives to 2 and 3 days, respectively. Our results indicate that the epidural administration of ropivacaine effectively blocks neuropathic pain without the induction of analgesic tolerance, and significantly delays the development of neuropathy produced by peripheral nerve injury. Epidural ropivacaine sustained release suspension produces much longer blockade effects of mechanical allodynia and heat hyperalgesia, and more significantly delays the development of neuropathic pain.
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Matrix metalloproteinases (MMPs) are widely implicated in inflammation and tissue remodeling associated with various neurodegenerative diseases and play an important role in nociception and allodynia. Extracellular Matrix Metalloproteinase Inducer (EMMPRIN) plays a key regulatory role for MMP activities. However, the role of EMMPRIN in the development of neuropathic pain is not clear. ⋯ In conclusion, peripheral nerve injury induced upregulation of OX47 in the extracellular matrix of DRG. RNA interference against OX47 significantly suppressed the expression of OX47 mRNA and the development of mechanical allodynia. The altered expression of OX47 may contribute to the development of neuropathic pain after nerve injury.
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We investigated whether milnacipran, a serotonin-noradrenaline reuptake inhibitor, would have therapeutic effect on oxaliplatin-induced mechanical allodynia in mice. A single intraperitoneal injection of oxaliplatin (3 mg/kg) induced mechanical allodynia, which peaked on day 10 after injection and almost completely subsided by day 20. ⋯ Intrathecal injections of milnacipran (2.1-21 µg/site) also significantly and dose-dependently inhibited mechanical allodynia, but intracisternal and intracereboventricular injections at the same doses did not. The present results suggest that milnacipran is effective against oxaliplatin-induced mechanical allodynia and that the antiallodynic effect is mainly mediated by actions on the spinal cord.
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Remifentanil (an ultra-short acting μ-opioid receptor agonist) use has been associated with acute opioid tolerance and hyperalgesia. Previous electrophysiological studies have shown that remifentanil elicits rapid and prolonged upregulation of N-methyl-D-aspartate receptor (NMDAR) currents. However, the effect of remifentanil on the levels of the GluN1 subunit of the NMDAR in dorsal horn neurons (DHNs) has not been reported. ⋯ GluN1 mRNA and protein levels, determined by real time reverse transcription polymerase chain reaction (RT-PCR) and Western blot, respectively, were significantly and persistently increased by remifentanil exposure compared with the control group (P ＜ 0.05). These results may partially account for the mechanism of remifentanil-induced hyperalgesia. This increase was prevented by ketamine (NMDAR antagonist) and naloxone (μ-opioid receptors antagonist), thus providing a potential therapeutic mechanism for the prevention of opioid-induced hyperalgesia.