Articles: hyperalgesia.
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Ann. N. Y. Acad. Sci. · Jun 2010
Role of NKCC1 and KCC2 in the development of chronic neuropathic pain following spinal cord injury.
Neuropathic pain is a common problem following spinal cord injury (SCI). Effective analgesic therapy has been hampered by the lack of knowledge about the mechanisms underlying post-SCI neuropathic pain. Current evidence suggests GABAergic spinal nociceptive processing is a critical functional node in this complex phenotype, representing a potential target for therapeutic intervention. ⋯ Inhibition of NKCC1 with its potent antagonist bumetanide reduces pain behavior in rats following SCI. Moreover, the injured spinal cord tissues exhibit a significant transient upregulation of NKCC1 protein and a concurrent downregulation of KCC2 protein. Thus, imbalanced function of NKCC1 and KCC2 may contribute to the induction and maintenance of the chronic neuropathic pain following SCI.
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J Pain Palliat Care Pharmacother · Jun 2010
Patients with chronic pain after abdominal surgery show less preoperative endogenous pain inhibition and more postoperative hyperalgesia: a pilot study.
Chronic pain is common and undesirable after surgery. Progression from acute to chronic pain involves altered pain processing. The authors studied relationships between presence of chronic pain versus preoperative descending pain control (diffuse noxious inhibitory controls; DNICs) and postoperative persistence and spread of skin and deep tissue hyperalgesia (change in electric/pressure pain tolerance thresholds; ePTT/pPTT) up to 6 months postoperatively. ⋯ More inhibitory pDNIC was linked to less postoperative leg deep tissue hyperalgesia, without affecting pain VAS. This pilot study for the first time links chronic pain after surgery, poorer preoperative inhibitory pain modulation (DNIC), and greater postoperative degree, persistence, and spread of hyperalgesia. If confirmed, these results support the potential clinical utility of perioperative pain processing testing.
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Exp Clin Psychopharmacol · Jun 2010
Randomized Controlled Trial Clinical TrialDifferential effect of codeine on thermal nociceptive sensitivity in sleepy versus nonsleepy healthy subjects.
Basal sleepiness-alertness modulates drug effects. Sleepiness produced by sleep restriction leads to increased nociceptive sensitivity, suggesting opioid analgesia may also be modulated by sleepiness-alertness. This study compared thermal nociceptive sensitivity in sleepy versus nonsleepy participants after codeine or placebo. ⋯ More important, there was a Group x Drug interaction with codeine increasing FWL in the nonsleepy, but not the sleepy, group. These data show the analgesic effects of codeine are diminished in sleepy versus nonsleepy individuals. They suggest clinical differences in response to analgesics are partly explained by basal state of sleepiness-alertness.
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Comparative Study
Comparison of self-reported cutaneous allodynia and brushing allodynia during migraine attacks.
This study compares the results of brushing allodynia (BA) during migraine attacks to those of self-reported cutaneous allodynia. We recruited 100 patients (20 with chronic migraine, 80 with episodic migraine) and performed a gauze-brushing test to detect BA. A previous experience of cutaneous allodynia was queried. ⋯ Some allodynia symptoms, including avoidance of washing hair, touching the head, combing hair and lying on the site of head pain, were associated with BA (all p < .05). Our study showed that BA during migraine attacks correlated well with prior allodynia symptoms. The frequencies of BA and self-reported allodynia depend on the composition of different migraine subtypes and the timing of the gauze-brushing test.
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Given that the pharmacological or genetic inactivation of fatty acid amide hydrolase (FAAH) counteracts pain and inflammation, and on the basis of the established involvement of transient receptor potential vanilloid type-1 (TRPV1) channels in inflammatory pain, we tested the capability of a dual FAAH/TRPV1 blocker, N-arachidonoyl-serotonin (AA-5-HT), to relieve oedema and pain in a model of acute inflammation, and compared its efficacy with that of a single FAAH inhibitor (URB597) or TRPV1 antagonist (capsazepine). Acute inflammation was induced by intraplantar injection of lambda-carrageenan into mice and the anti-inflammatory and anti-nociceptive actions of AA-5-HT were assessed at different doses, time points and treatment schedule. In addition, endocannabinoid levels were measured in paw skin and spinal cord. ⋯ AA-5-HT was more potent than capsazepine as anti-oedemigen and anti-hyperalgesic drug, whereas it shows an anti-oedemigen property similar to URB597, which was, however, devoid of the anti-nociceptive effect. AA-5-HT did not induce unwanted effects on locomotion and body temperature. In conclusion AA-5-HT has both anti-inflammatory and anti-hyperalgesic properties and its employment offers advantages, in terms of efficacy and lack of adverse effects, deriving from its dual activity.