Articles: hyperalgesia.
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Acta Anaesthesiol Scand · Sep 2001
Randomized Controlled Trial Clinical TrialEffect of naloxone on primary and secondary hyperalgesia induced by the human burn injury model.
Opioid antagonists may change the responses in models of experimental hyperalgesia. This indicates a possible involvement of the endogenous opioid system in these models. The aim of the present study was to evaluate whether activation of the endogenous opioid system could be demonstrated in the human burn injury model of cutaneous hyperalgesia, using an intravenous challenge with the non-selective opioid antagonist naloxone. ⋯ Activation of an endogenous opioid response following induction of hyperalgesia in human volunteers by a burn injury could not be demonstrated with an intravenous naloxone challenge. These findings suggest that the endogenous opioid response is not a confounding factor in this model.
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To review the pathophysiology of fibromyalgia syndrome. ⋯ Multiple abnormal findings in fibromyalgia patients strongly indicate a neuropathic pain syndrome, reminiscent of complex regional pain syndrome or postherpetic neuralgia. In addition, fibromyalgia syndrome seems to share similar characteristics with these neuropathic pain syndromes, including ineffective response to many analgesics.
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We examined the effects of intrathecally preadministered injections of a phosphorothioate analog of c-fos antisense and mismatch oligodeoxynucleotides (ODNs) on the withdrawal latency to a thermal stimulus following unilateral injection of complete Freund's adjuvant (CFA) into the hind footpad of rats. Pretreatment with the c-fos antisense ODN significantly decreased the CFA-induced expression of c-Fos protein dose-dependently in ipsilateral laminae I/II (LI/II) of the dorsal horn (mean +/- SEM per section: 10 nM ODN, 43.9+/-1.3; 25 nM ODN, 19.4+/-4.1) compared with pretreatment with the mismatch ODN (63.6+/-2.9; 60.6+/-4.0) or saline (56.6+/-5.5). ⋯ Pretreatment with 10 nM antisense ODN had a less significant effect. These results indicate that the expression of CFA-induced c-Fos in the dorsal horn might facilitate thermal nociception.
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Reg Anesth Pain Med · Sep 2001
Randomized Controlled Trial Clinical TrialEffect of systemic adenosine on pain and secondary hyperalgesia associated with the heat/capsaicin sensitization model in healthy volunteers.
Adenosine is an endogenous compound that may have analgesic effects. Results from clinical trials are not consistent, however, and there is a need for large-scale, randomized, placebo-controlled studies to clarify the role of adenosine in the treatment of pain states, including acute nociceptive pain and pain involving central sensitization. ⋯ We conclude that adenosine has no effect on acute nociceptive pain induced by heat stimulation or on secondary hyperalgesia induced by heat/capsaicin sensitization in healthy volunteers.
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Br J Clin Pharmacol · Sep 2001
Clinical TrialRepeated local administration of noradrenaline or saline inhibits thermal hyperalgesia in pain-sensitized human skin.
Noradrenaline increases thermal hyperalgesia in skin sensitized to heat by the topical application of capsaicin. The aim of this study was to determine whether desensitization to the hyperalgesic effects of noradrenaline would develop after repeated local administrations of noradrenaline in the skin of the forearm. ⋯ We conclude that repeated iontophoreses of noradrenaline or saline inhibit vasoconstriction to noradrenaline, and also inhibit increases in thermal hyperalgesia evoked by capsaicin. The release of endogenous stores of noradrenaline by iontophoretic currents might contribute to these effects.