European journal of pain : EJP
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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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Inflammatory mediators activate and sensitize nociceptors. Tissue acidosis with low pH of 5.5 often accompanies inflammation and could enhance inflammatory pain and sensitization. ⋯ Our results confirm nociceptor class independent heat sensitization by PGE2 which is probably mediated by transient receptor potential vanilloid 1 phosphorylation. However, prolonged and increased pain responses in humans upon low pH/PGE2 stimulation appear to be primarily dependent on CMi fibres, whereas CM nociceptors appear crucial for phasic responses.