Articles: hyperalgesia.
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We describe an animal model of nociceptive sensory neuropathy induced by repeat intravenous administration of oxaliplatin in which treated animals partly reproduce the characteristic pain symptoms in oxaliplatin-treated patients. We tested the ability of 1, 2 and 4 mg/kg oxaliplatin doses injected twice-weekly for four-and-a-half consecutive weeks to induce a nociceptive peripheral neuropathy in male Sprague-Dawley rats. ⋯ The 2mg/kg oxaliplatin dose and the tail-immersion test in cold water (10 degrees C) were selected to compare pharmacological sensitivity between single administered drugs as morphine, lidocaine, carbamazepine, gabapentin and repeated administration of drugs as clomipramine, venlafaxine, calcium and magnesium solutions. Magnesium solution (90 mg/kg) and venlafaxine (7.5 mg/kg) administration induced an antinociceptive effect whereas gabapentin (300 mg/kg), clomipramine (2.5 mg/kg) and lidocaine (3 and 6 mg/kg) only induced an antiallodynic effect.
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Anesthesia and analgesia · Apr 2007
Intravenous mononuclear marrow cells reverse neuropathic pain from experimental mononeuropathy.
Stem cells mediate neuroprotection in a variety of nervous system injury models. In this study, we evaluated a potential role for stem cells in pain therapies. Marrow mononuclear cells containing mixed stem cell populations were used because of wide experience with these cells in experimental and clinical transplantation. ⋯ These studies suggest that stem or progenitor cell-mediated therapies may be useful for the treatment of pain after nerve injury, and deserve further study to elucidate the mechanisms of analgesia.
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Intra-articular injection of mono-iodoacetate (MIA) in the rat knee joint induces a histopathology with similarities to osteoarthritis (OA). Typically, a synovitis (days 1-3) is observed followed by thinning of articular cartilage and subsequent lesion of subchondral bone at days 8-14 onwards. Behaviourally, weight-bearing asymmetry is observed, which is sensitive to anti-inflammatory pharmacology at early but not later (days 14+) time points. ⋯ Significant resolution of weight-bearing was observed at high and intermediate doses of amitriptyline and gabapentin at all time points (P<0.05, ANOVA, post-hoc Bonferroni's, vs pre-dose measurements). Transient and weak effects were observed with naproxen (10mg/kg) on days 14 and 28, whereas celecoxib showed no significant effects. Collectively, these data suggest that this putative model of OA is associated with an early phase neuropathy in the L5 innervation territory of the knee.
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Experimental neurology · Apr 2007
Effects of decompression on neuropathic pain behaviors and skin reinnervation in chronic constriction injury.
Decompression is an important therapeutic strategy to relieve neuropathic pain clinically; there is, however, lack of animal models to study its temporal course of neuropathic pain behaviors and its influence on nerve regeneration to sensory targets. To address these issues, we established a model of decompression on rats with chronic constriction injury (CCI) and investigated the effect on skin reinnervation. Animals were divided into a decompression group, in which the ligatures were removed, and a CCI group, in which the ligatures remained at postoperative week 4 (POW 4). ⋯ At POW 8, neuropathic pain behaviors had completely disappeared in the decompression group, and the decompression group had a higher skin innervation index of SP than the CCI group (0.45+/-0.05 vs. 0.16+/-0.03, p<0.001). These indexes were similar in both groups for PGP 9.5 (0.32+/-0.09 vs. 0.14+/-0.04, p=0.11) and CGRP (0.38+/-0.06 vs. 0.21+/-0.07, p=0.09). These findings demonstrate the temporal changes in the disappearance of neuropathic pain behaviors after decompression and suggest that decompression causes different patterns of skin reinnervation for different markers of skin innervation.
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Chronic muscle pain is a problem with high prevalence in clinical practice and its pharmacological treatment is difficult. There is a lack of animal models which reliably predict analgesic activity of drugs on muscle pain. Here we used intramuscular injection of tumor necrosis factor-alpha (TNF) in rats as a model of muscle pain. ⋯ In biceps muscle hyperalgesia, a significant reversal of hyperalgesia was seen with lacosamide at 10mg/kg. Significant effects were also seen for pregabalin and gabapentin at 100mg/kg. We could thus demonstrate in a rat model for myalgia that lacosamide effectively reduces muscular hyperalgesia and is somewhat more potent than gabapentin and pregabalin.