Articles: hyperalgesia.
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J Pain Symptom Manage · Jul 1998
Randomized Controlled Trial Clinical TrialThe human capsaicin model of allodynia and hyperalgesia: sources of variability and methods for reduction.
Intradermal and topical application of capsaicin have been used to study mechanisms of mechanical allodynia (MA) and pinprick hyperalgesia (PPH) and the efficacy of drugs in relieving these symptoms. However, it is associated with significant inter- and intra-subject variability. In order to improve the model's sensitivity, we examined several potential sources of variability of capsaicin-evoked MA and PPH in healthy volunteers, including skin temperature fluctuations, method (intradermal vs. topical) and site (volar forearm vs. foot dorsum) of administration. ⋯ However, greater intra-subject consistency (MA: foot: r = 0.84; arm: r = 0.49; PPH: r = 0.87; r = 0.39) and significantly larger areas of MA (15.8 +/- 4.2 vs 9.1 +/- 2.5, p < 0.05) were seen with the foot. (PPH: foot: 28.9 +/- 6.7; arm: 21.6 +/- 4.2, NS). Large variability exists among subjects receiving CAP, with some developing minimal MA. However, these subjects may be screened out prior to entry, increasing the sensitivity of the model, which may be further improved by clamping the skin temperature.
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Psychological medicine · Jul 1998
Clinical Trial Controlled Clinical TrialLower serum activity of prolyl endopeptidase in fibromyalgia is related to severity of depressive symptoms and pressure hyperalgesia.
The aims of the present study were to examine serum activities of peptidases, i.e. prolyl endopeptidase (PEP) and dipeptidyl peptidase IV (DPP IV), in patients with fibromyalgia and to examine the effects of subchronic treatment with sertraline on these variables. ⋯ The results show that fibromyalgia, and aberrant pain perception and depressive symptoms in fibromyalgia are related to lower serum PEP activity. It is hypothesized that lower serum PEP activity may play a role in the biophysiology of fibromyalgia through diminished inactivation of algesic and depression-related peptides.
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The present study examined the effects of intrathecal (i.t.) treatment (twice-daily injections on post-operative (PO) days 0-8) with the metabotropic glutamate receptor (mGluR) compound, (S)-4-carboxyphenylglycine ((S)-4CPG), or the non-competitive N-methyl-D-aspartate (NMDA) antagonist, dizocilipine maleate (MK-801), on mechanical allodynia and cold hyperalgesia associated with chronic constriction injury (CCI) of the sciatic nerve in rats. Also, the effects of early (twice-daily injections on days 0-3) or late (twice-daily injections on days 8-11) (S)-4CPG treatment on the injury-related mechanical allodynia and cold hyperalgesia were assessed in CCI rats. ⋯ However, late treatment with (S)-4CPG did not reduce the nociceptive behaviours in either behavioural task. These data not only confirm that the NMDA receptor plays a role in chronic nociception, but also suggest that Group I mGluRs are more critically involved in the development, and not the maintenance, of mechanical allodynia and cold hyperalgesia associated with CCI in rats.
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The current study aimed to assess whether local administration of morphine could block the development of hyperalgesia and allodynia in a rat model of osteotomy or bone damage. ⋯ This study shows that local application of a low dose of morphine effectively blocks the development of hyperalgesia and allodynia in a rat model of bone damage through mu-opioid receptor action. These findings provide further evidence that local application of morphine at the time of orthopedic surgery, bone graft, or bone marrow harvesting may reduce the amount of postoperative pain.
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The influence of midthoracic spinalization on thermally and mechanically induced spinal withdrawal reflex responses was studied in the rat. There were three experimental groups of rats: healthy controls, rats with a spinal nerve ligation-induced unilateral neuropathy, and rats with a carrageenan-induced inflammation of one hindpaw. Tail flick response was induced by radiant heat. ⋯ In contrast, spinal withdrawal responses induced by noxious cold or mechanical stimulation were significantly suppressed following spinalization. The spinalization-induced facilitatory effects as well as inhibitory ones on spinal reflexes were enhanced in inflamed/neuropathic animals. The results indicate that the tonic descending control of spinal nocifensive responses varies depending on the submodality of the test stimulus, the segmental level of the reflex (tail vs. hindlimb), and on the pathophysiological condition.