Allodynia, mechanical

Facilitates GI transit/mechanical intestinal allodynia Cardiac arrhythmia... 

Clinical pain is characterized by the presence of spontaneous pain or hypersensitivity to pain-provoking stimuli. Hypersensitivity includes pain produced by low-intensity stimuli that normally only elicit an innocuous sensation (allodynia), or an exaggerated response to a noxious stimulus (hyperalgesia). There are two distinct forms of clinical pain, the pain that occurs after tissue injury or inflammatory diseases (inflammatory pain) and the pain associated with a lesion or disease of the nervous system (neuropathic pain). Although the mechanisms responsible for the initiation and maintenance of these pains differ, they are both characterized by heightened... 

The uncompetitive NMDA receptor antagonist ketamine has been available for clinical use as an anaesthetic for 40 years (Domino et al. 1965). Ketamine is effective in various animal models of hyperalgesia and allodynia and has been reported to have antinociceptive effects in some of these models at doses devoid of obvious side-effects. Others, however, have reported that the effects of ketamine are only seen at doses producing ataxia (see Parsons 2001 for review). Ketamine reportedly inhibits the area of secondary hyperalgesia induced by chemical (Park et al. 1995) or thermal stimuli (Ilkjaer et al. 1996 Warncke et al. 1997) and inhibits temporal siunmation of repeated mechanical (Warncke et al. 1997) and electrical stimuli (Arendtnielsen et al. 1995 Andersen et al. 

Chronic constriction injury (CCI) models (Bennett and Xie, 1988 Kim and Chung, 1992 Mosconi and Kruger, 1996) have been used to examine chronic pain states in experimental animals. In these models, intrathecally administered a2-agonists reduced mechanical allodynia and thermal hyperalgesia that developed following nerve constriction (Levy et al., 1994 Yaksh et al., 1995). This... 

Tactile allodynia (UV burn, hindoaw) SNX-111 0.3 pg i.t. 4-fold increase in the hindpaw withdrawal threshold to mechan.stim. Bowersox et al. (1998)... 

Quartaroli, M., Fasdelli, N., Bettelini, L., Maraia, G., Corsi, M. GV196771A, an NMDA receptor/glycine site antagonist, attenuates mechanical allodynia in neuropathic rats and reduces tolerance induced by morphine in mice, Eur. J. Pharmacol. 2001, 430, 219-227. 

Sutton, J.L., Maccecchini, M.L., Kajander, K.C. The kainate receptor antagonist 2S,4R-4-methylglutamate attenuates mechanical allodynia and thermal hyperalgesia in a rat model of nerve injury, Neuroscience 1999, 91, 283-292. 

Bennett, A.D., Chastain, K.M., Hulsebosch, C.E. Alleviation of mechanical and thermal allodynia by CGRP(8-37) in a rodent model of chronic central pain, Pain 2000, 86, 163-175. 

Nerve injury, followed by pain related behaviour, is induced by loose ligation of the ischiatic nerve of one hind paw of the rat. 3-4 weeks after ligation, neuropathic pain-like behaviour is seen as increased sensitivity towards heat and pressure stimuli (hyperalgesia). Also pain reactions toward non-noxious tactile (mechanical allodynia) or cold stimuli (cold allodynia) can be observed. Mechanical allodynia is tested with von Frey hairs and cold allodynia by putting the animals on metal plate cooled to 4 °C. The number of paw liftings is counted (Bennett and Xie, Pain 1988, 33, 87-107). 

This ability to test drugs in contexts other than acute pain models has arisen from good communication between bench scientists, clinicians and industry. Until recently investigations into the mechanisms of clinical pain syndromes all relied on animal studies using acute stimuli. The symptoms of pain arising from nerve injury, neuropathic pain, such as allodynia, spontaneous pain, hyperalgesia, sensory deficits and in some cases a sympathetic component are simply not seen in the older acute models. There are now several animal models which mimic peripheral and central neuropathic states. The same is true for inflammation. 

Yamamoto T., Nozaki-Taguchi N., and Sakashita Y. (2001). Spinal N-acetyl-alpha-linked acidic dipeptidase (NAALADase) inhibition attenuates mechanical allodynia induced by paw carrageenan injection in the rat. Brain Res. 909 138-144. 

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