Articles: hyperalgesia.
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Anasthesiol Intensivmed Notfallmed Schmerzther · Feb 2015
Review[Perioperative management of patients with opioid tolerance and misuse].
Patients with opioid pretreatment can be divided into different groups. While patients after successful drug addiction treatment with or without drug replacement therapy usually not require an extensive perioperative pain therapy, patients with persistent chronic pain and patients with an existing opioid addiction regularly are challenging for the anesthetist. Important pathophysiological issues among the patients include opioid tolerance, opioid-induced hyperalgesia (OIH) as well as acute withdrawal symptomes. ⋯ A similar statement applies to clonidine and dexmedetomidine, which probably induce analgesia by activation of the descending antinociceptive noradrenergic system. The intraoperative administration of S-ketamine is recommended for patients who either already have developed opioid tolerance or suffer from neuropathic pain, and by which postoperative pain is high and was already shown to be poorly adjusted. Other therapeutic options such as intraoperative administration of magnesium or lidocaine may be promising approaches.
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Anesthesia and analgesia · Feb 2015
Spontaneous Pain-Like Behaviors Are More Sensitive to Morphine and Buprenorphine Than Mechanically Evoked Behaviors in a Rat Model of Acute Postoperative Pain.
Nonevoked spontaneous pain is most problematic for postoperative patients. Physicians assess this form of pain using the human visual analog scale or verbal numeric rating scale. Recent studies have proposed that spontaneous foot-lifting (SFL) behaviors are an expression of spontaneous pain in animals after spinal nerve injury or adjuvant-induced inflammation. In the current study, we characterize SFL behaviors in a rat model of acute postoperative pain, which includes comparisons with evoked behaviors to analgesic treatments. ⋯ The present study demonstrates that a hindpaw plantar incision induces SFL behaviors in rats and that these behaviors have higher bioassay sensitivity to analgesic interventions with morphine and buprenorphine compared with mechanically evoked behaviors.
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Activation of extracellular signal-regulated kinases (ERK1/2) has been shown to play an important role in several pain states. Here we investigated the ERK1/2 contribution to non-evoked and evoked pain-like behaviour in rats after surgical incision. ⋯ The results suggest that spinal ERK1 and ERK2 are involved in regulation of pain after incision differentially with regard to the pain modality. Furthermore, blockade of ERK1/2 activation was most effective in a preventive manner, a condition which is rare after incision. Spinal ERK1/2 inhibition could therefore be a very useful tool to manage selectively movement-evoked pain after surgery in the future.
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Journal of neurochemistry · Feb 2015
CXCL12/CXCR4 chemokine signaling in spinal glia induces pain hypersensitivity through MAPKs-mediated neuroinflammation in bone cancer rats.
The activation of MAPK pathways in spinal cord and subsequent production of proinflammatory cytokines in glial cells contribute to the development of spinal central sensitization, the basic mechanism underlying bone cancer pain (BCP). Our previous study showed that spinal CXCL12 from astrocytes mediates BCP generation by binding to CXCR4 in both astrocyters and microglia. Here, we verified that CXCL12/CXCR4 signaling contributed to BCP through a MAPK-mediated mechanism. ⋯ Among them, CXCL12 could reinforce the astrocytic and microglial activation in autocrine and paracrine manners. Such positive feedback loops sustain perseverant neuroinflammation, facilitate glial activation, and finally lead to bone cancer pain. IL = interleukin; TNF = tumor necrosis factor.