Articles: hyperalgesia.
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Randomized Controlled Trial
Pre-treatment with morphine does not prevent the development of remifentanil-induced hyperalgesia.
Remifentanil, an ultra short-acting opioid commonly used to supplement general anesthesia, is associated with the development of hyperalgesia that manifests clinically as an increase in postoperative analgesic requirement. This study involving adolescents undergoing scoliosis surgery evaluated whether pre-treatment with morphine prior to commencing remifentanil infusion would decrease the initial 24-hr morphine consumption and pain scores. ⋯ Pre-treatment with 150 microg x kg(-1) morphine did not decrease the initial 24-hr morphine consumption in adolescents who received remifentanil by infusion for surgical correction of idiopathic scoliosis.
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Habituation and sensitization to heat and cold pain in women with fibromyalgia and healthy controls.
The purpose of this study was to examine differences in habituation to heat and cold pain in women with fibromyalgia (FM; n=33) and in women who were healthy controls (HC; n=44). Quantitative sensory testing (QST) was used to assess pain thresholds during five consecutive trials of ascending heat and descending cold stimulation. Anxiety, depression, fatigue, and pain during the previous week were assessed using self-report measures. ⋯ In addition, anxiety, depression, fatigue, and pain were related to decreased heat and cold pain thresholds in the overall sample. However, when group was controlled, none of these variables were related to thresholds or rates of habituation or sensitization. The differences between women with FM and healthy women in habituation and sensitization may have important implications for the etiology, diagnosis, and treatment of FM and other chronic pain conditions.
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Prostaglandins Leukot. Essent. Fatty Acids · Dec 2008
COX-2 expression and function in the hyperalgesic response to paw inflammation in mice.
Peripheral inflammation and edema are often accompanied by primary and secondary hyperalgesia which are mediated by both peripheral and central mechanisms. The role of cyclooxygenase-2 (COX-2)-mediated prostanoid production in hyperalgesia is a topic of substantial current interest. We have established a murine foot-pad inflammation model in which both pharmacologic and genetic tools can be used to characterize the role of COX-2 in hyperalgesia. ⋯ Zymosan-induced primary hyperalgesia in Cox-2-/- mice is similar to that of their Cox-2+/+ littermate controls. However, the central component of hyperalgesia is substantially reduced in Cox-2-/- versus Cox-2+/+ mice, and returns to baseline values much more rapidly. Thus pharmacological data suggest, and genetic experiments confirm, (i) that primary hyperalgesia in response to zymosan inflammation in the mouse paw is not mediated by COX-2 function and (ii) that COX-2 function plays a major role in the central component of hyperalgesia in this model of inflammation.
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Inflammatory pain, characterized by a decrease in the nociceptive threshold, arises through the actions of inflammatory mediators, and one of the key molecules is nerve growth factor (NGF). Here we report that the administration of neutralizing antibody to the neurotrophin receptor p75 (p75(NTR)) blocks hyperalgesia, which develops with complete Freund's adjuvant (CFA)-induced inflammation or with an intraplantar injection of NGF. Although CFA injection results in the up-regulation of calcitonin gene-related peptide (CGRP) levels in the primary sensory neurons, blocking p75(NTR) abolishes this effect. ⋯ In addition, an intraplantar injection of pro-NGF induces hyperalgesia. These data together suggest that pro-NGF, as well as mature NGF, binding to p75(NTR) plays an important role in inflammation-induced hyperalgesia. Interference in the binding may provide a therapeutic approach for the treatment of inflammatory pain.
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The roles of ion channels in sensory neurons were examined in experimental models of muscle pain in the rat. Rats were injected with 50 microl of 4% carrageenan or subjected to an eccentric exercise (ECC) of the gastrocnemius muscle (GM). The Randall-Selitto and von Frey tests were performed on the calves to evaluate mechanical hyperalgesia of the muscle. ⋯ Antagonists to TRP channels and ASICs showed suppressive effects for both carrageenan- and ECC-induced muscle hyperalgesia. The carrageenan injection and ECC models are useful models of acute inflammatory pain and delayed onset muscle soreness (DOMS), respectively, and the time course and underlying etiology might be different. TRP channels and ASICs are closely related to the development of muscle mechanical hyperalgesia, and TRPV1 is involved in ECC-induced DOMS.