Pain
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Comparative Study
Predictors of postoperative movement and resting pain following total knee replacement.
This study determined preoperative predictors of movement and resting pain following total knee replacement (TKR). We hypothesized that younger patients with higher preoperative pain intensity, pain sensitivity, trait anxiety, pain catastrophizing, and depression would be more likely to experience higher postoperative movement pain than older patients with lower scores on these variables prior to surgery, and that predictors would be similar for resting pain. Demographics, analgesic intake, anxiety, depression, pain catastrophizing, resting pain, movement pain (ie, during active knee range of motion), and quantitative sensory tests were performed preoperatively on 215 participants scheduled for a unilateral TKR. ⋯ These results suggest that patients with higher preoperative pain and depression are more likely to have higher pain following TKR, and younger patients may have higher resting pain. Cutaneous pain sensitivity predicted movement pain but not resting pain, suggesting that mechanisms underlying movement pain are different from resting pain. Aggressive management of preoperative pain, pain sensitivity, and depression prior to surgery may facilitate postoperative recovery.
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Comparative Study
Mechanical allodynia but not thermal hyperalgesia is impaired in mice deficient for ERK2 in the central nervous system.
Extracellular signal-regulated kinase (ERK) plays critical roles in pain plasticity. However, the specific contribution of ERK2 isoforms to pain plasticity is not necessarily elucidated. Here we investigate the function of ERK2 in mouse pain models. ⋯ In Erk2 CKO mice, compensatory hyperphosphorylation of ERK1 was detected in the spinal cord. However, ERK1 did not appear to influence nociceptive processing because the additional inhibition of ERK1 phosphorylation using MEK (MAPK/ERK kinase) inhibitor SL327 did not produce additional changes in formalin-induced spontaneous behaviors in Erk2 CKO mice. Together, these results indicate that ERK2 plays a predominant and/or specific role in pain plasticity, while the contribution of ERK1 is limited.
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The transient receptor potential vanilloid channel 1 (TRPV1) is a nociceptive transducer located on nociceptive neurons. TRPV1 channels located on peripheral neurons mainly transduce the sense of heat and are also activated by low pH or capsaicin. The role of centrally located TRPV1 channels is not fully understood. ⋯ The results show that olvanil dose-dependently inhibited spontaneous and stimulus-induced activity within the trigeminocervical complex, whereas it had no effect on CSD susceptibility. We further demonstrated that the inhibiting effect of olvanil is mediated by vanilloid and cannabinoid receptor systems, thereby using the synergistic effects this dual mechanism offers. Curiously, TRPV1 receptor agonism may have anti-nociceptive properties through central mechanisms that would be of considerable interest to elucidate.