Articles: hyperalgesia.
-
Randomized Controlled Trial Comparative Study
Spatial and temporal aspects of muscle hyperalgesia induced by nerve growth factor in humans.
Intramuscular injection of nerve growth factor (NGF) has been shown to induce long-term sensitisation and time-dependent hyperalgesia indicating potential involvement of both central and peripheral pain mechanisms. This double-blind placebo-controlled study was designed to describe the spatial distribution of muscle hyperalgesia over time (immediately after, 3 h, 1, 4, 7 and 21 days) after injecting NGF (5 mug) into the tibialis anterior (TA) muscle, to explore possibly involved central pain mechanisms and to investigate the effect of gender on development of hyperalgesia. Totally 20 healthy volunteers (10 men and 10 women) participated in the study. ⋯ Injection of NGF increased muscle soreness during muscle activity for 7 days. In this material there was no gender effect of NGF-induced muscle hyperalgesia. The expansion of muscle hyperalgesia to distant areas indicates that central mechanisms are involved.
-
Carriers of a particular haplotype of the GTP cyclohydrolase gene (GCH1) had less pain after surgery for chronic lumbar radiculopathy and a decreased sensitivity to some experimental mechanical pain stimuli. Ex-vivo, GCH1 upregulation and BH4 production after forskolin stimulation were reduced, while baseline BH4 concentrations were not affected. This suggested that the haplotype may mainly exert its modulating function when the GCH1 system is provoked. The present study aimed at (i) testing this hypothesis and (ii) independently reproducing the pain-decreasing effects of a particular GCH1 haplotype having been previously associated with pain protection. ⋯ This study verifies previous results that decreased GCH1 function or inducibility as a result of genetic polymorphisms protects against pain. This study extents previous results by showing that this pain protection is mainly conferred under conditions of hyperalgesia resulting from sensitization, supporting specific functions of BH4 in relation to particular aspects of pain.
-
Am. J. Gastroenterol. · Nov 2008
Somatosensory hypersensitivity in the referred pain area in patients with chronic biliary pain and a sphincter of Oddi dysfunction: new aspects of an almost forgotten pathogenetic mechanism.
Somatosensory hyperalgesia in the referred pain area (RPA) in patients with acute or chronic abdominal pain syndromes may result from the convergence of nerve fibers from visceral and somatic tissues at the spinal and supraspinal levels. Chronic biliary pain in patients with the postcholecystectomy syndrome (i.e., biliary hypersensitivity) may be explained by persistent hyperexcitability of neurons in the central nervous system (CNS). The aim of this study was to evaluate the cutaneous neural sensory perception in the RPA in patients with chronic postcholecystectomy biliary pain and a sphincter of Oddi (SO) dysfunction (SOD). ⋯ Continuous visceral pain (biliary pain) caused by local inflammatory/sensitizing processes or a CNS malfunction could lead to significant hypersensitivity of the peripheral nociceptive nerve fibers in SOD patients. Postcholecystectomy pain may be explained by persistent hyperexcitability of the nociceptive neurons in the CNS with or without objective motility disorders of the SO.
-
Antidepressant drugs act mainly by blocking the noradrenaline and/or serotonin uptake sites and require a chronic treatment. Tricyclic antidepressants are among the first line treatments clinically recommended against neuropathic pain. As observed against depression, a chronic treatment is required for a therapeutic effect. ⋯ For comparison, we tested the anticonvulsant gabapentin and showed that it alleviates neuropathic allodynia after 3 days of treatment. Naloxone had no effect on gabapentin therapeutic benefit, showing that antidepressants and anticonvulsants alleviate neuropathic allodynia through independent mechanisms. Our work provides a clinically relevant model to understand the mechanism by which chronic antidepressant treatment can alleviate neuropathic pain.
-
Journal of neurotrauma · Nov 2008
Capsular ligament involvement in the development of mechanical hyperalgesia after facet joint loading: behavioral and inflammatory outcomes in a rodent model of pain.
Whiplash injury can produce pain in the neck, arm, and hand, and has been associated with inflammation. However, the relationship between inflammatory responses and pain symptoms remains unknown, hindering the development of appropriate therapeutics for whiplash symptoms. Two joint loading paradigms were used separately in an established rat model of painful cervical facet joint distraction to apply: (1) gross failure, and (2) subfailure distraction of the facet capsular ligament. ⋯ Cytokine mRNA levels in the spinal cord and DRG were also significantly elevated after facet ligament failure, but not after painful subfailure loading. Findings suggest that different joint loading scenarios produced varied inflammatory responses in the CNS. These data support existing clinical reports suggesting that therapeutic interventions directed at the facet capsule may be effective in treating this painful injury.