Articles: hyperalgesia.
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Neuroscience letters · Aug 2002
Inhibitory effects of intrathecally administered interleukin-1beta on carrageenan-induced hyperalgesia and spinal c-Fos expression in rats.
The present study investigated the effects of interleukin-1beta (IL-1beta) injected intrathecally (i.t.) on carrageenan-induced thermal hyperalgesia and spinal c-Fos expression. The paw withdrawal latency (PWL) by the thermal stimulus was taken as an index of the thermal hyperalgesia of rats. I.t. injection of 10 ng IL-1beta significantly increased the PWL of the carrageenan-injected paw. ⋯ Three hours after i.pl. injection of carrageenan, the number of c-Fos-like immunoreactive (c-Fos-LI) neurons was significantly increased in laminae I-II, III-IV and V-VI of the ipsilateral spinal cord at L4-5 with the higher density in laminae I-II and V-VI. I.t. pre-injected IL-1beta significantly decreased the number of carrageenan-induced c-Fos-LI neurons in laminae I-II in the ipsilateral spinal cord and also inhibited the hyperalgesia induced by i.pl. carrageenan. These results suggested that i.t. injection of IL-1beta suppressed the central nociceptive input into laminae I-II and produced an antinociceptive effect.
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Neuroscience letters · Aug 2002
Nerve growth factor induces systemic hyperalgesia after thoracic burn injury in the rat.
Acute burn injury is usually associated with pain in the injured and nearby areas. However, we have recently reported that a thoracic scald induces hindpaw hyperalgesia during the healing stage in rats. ⋯ The concentration of nerve growth factor (NGF) in the skin of the chest increased markedly during the healing stage. Moreover, rats injected daily with anti-NGF serum after burn injury did not develop hyperalgesia, suggesting that increased NGF in the tissue of the healing skin is a key factor causing systemic hyperalgesia during the recovery stage.
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Neuroscience letters · Aug 2002
Involvement of adenosine in the anti-allodynic effect of amitriptyline in streptozotocin-induced diabetic rats.
Recent observations suggest the involvement of adenosine in the peripheral antinociceptive effect of amitriptyline in nerve-injury-induced neuropathic pain. The aim of the present investigation was to evaluate, firstly, the peripheral and systemic effects of amitriptyline on tactile allodynia in the streptozotocin (STZ)-induced diabetic rat model of neuropathic pain and, secondly, whether caffeine coadministration affects the actions of amitriptyline. Diabetes was induced by a single intraperitoneal (i.p.) injection of STZ (50 mg/kg), and tactile allodynia was detected by application of von Frey filaments to the ventral surface of the hindpaw. ⋯ Coadministration of caffeine (5 mg/kg, i.p.; 1500 nmol, s.c.), at doses which produced no effect on its own, partially reversed systemic and local anti-allodynic effects of amitriptyline. These results indicate an anti-allodynic effect of both peripheral and systemic amitriptyline, and suggest the involvement of endogenous adenosine in the action of amitriptyline in this rat model of painful diabetic neuropathy. These data also suggest that topical application of tricyclic antidepressants may be useful in treating neuropathic pain in diabetics.
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An electrophysiologic study to examine effects of exogenous application of tumor necrosis factor-alpha (TNF-alpha ) activities and nociresponses of dorsal horn neurons in the spinal cord at L5. ⋯ These results suggest the possibility that TNF-alpha produced in the vicinity of nerve roots due to disc herniation might cause ectopic discharges in primary afferent fibers and thereby induce the prolonged excitation in pain-processing neurons responsible for radicular pain.
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Animal models of neuropathic pain have significantly advanced our knowledge of abnormalities in central pain processing mechanisms in chronic pain disorders. New neuroimaging techniques using functional magnetic resonance imaging and positron emission tomography scanning are beginning to provide insight into cortical participation in the processing of pain. Irritable bowel syndrome (IBS) is one of the most common gastrointestinal disorders seen by physicians. ⋯ Patients with IBS also have many extraintestinal symptoms consistent with a central hyperalgesic state. Recent studies suggest that patients with IBS may also have cutaneous hyperalgesia similar to that seen in other chronic pain disorders such as fibromyalgia. This suggests that abnormalities of central nociceptive processing are present in IBS.