Tactile allodynia

The sensation of pain, following injury or disease, in response to a previously non-noxious stimulus is termed allodynia . Tactile allodynia is caused by... 

Association of Pain, neuropathic pain is defined as pain initiated or caused by a primary lesion, dysfunction in the nervous system". Neuropathy can be divided broadly into peripheral and central neuropathic pain, depending on whether the primary lesion or dysfunction is situated in the peripheral or central nervous system. In the periphery, neuropathic pain can result from disease or inflammatory states that affect peripheral nerves (e.g. diabetes mellitus, herpes zoster, HIV) or alternatively due to neuroma formation (amputation, nerve transection), nerve compression (e.g. tumours, entrapment) or other injuries (e.g. nerve crush, trauma). Central pain syndromes, on the other hand, result from alterations in different regions of the brain or the spinal cord. Examples include tumour or trauma affecting particular CNS structures (e.g. brainstem and thalamus) or spinal cord injury. Both the symptoms and origins of neuropathic pain are extremely diverse. Due to this variability, neuropathic pain syndromes are often difficult to treat. Some of the clinical symptoms associated with this condition include spontaneous pain, tactile allodynia (touch-evoked pain), hyperalgesia (enhanced responses to a painful stimulus) and sensory deficits. 

Ectopic activity in C fibers elicits central sensitization in the dorsal horn, contributing to the generation of tactile allodynia, a prominent feature of neuropathic pain. 

Tsuda, M. et al. P2X4 receptors induced in spinal microglia gate tactile allodynia after nerve injury. Nature424 778-783, 2003. 

SNX-111, when given alone, is active in the Chung model (spinal nerve ligation), tactile allodynia test (hindpaw UV burn) and paw pressure test. In the hot plate assay there is only a small but significant effect of about 20% increase in response latency (Table 4, Malmberg and Yaksh, 1994). 

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)... 

Chung model of neuropathic pain Nerve injury in rats is induced by a tight ligation of the root of the spinal nerve at L5-L6. Animals show hyperalgesia and allodynia similar to the Bennet model. Tactile allodynia, measured with von Frey hairs, is the most reliable parameter of pain intensity in this model (Kim and Chung, Pain 1992, 50, 355-363). 

Maeda, T., Kiguchi, N., Kobayashi, Y., Ozaki, M., and Kishioka, S. (2008). Pioglitazone attenuates tactile allodynia and thermal hyperalgesia in mice subjected to peripheral nerve injury. J. Pharmacol. Sci. 108, 341-347. 

Tsuda, M., Shigemoto-Mogami, Y., Koizumi, S., Mizokoshi, A., Kohsaka, S., Salter, M. W., and Inoue, K. (2003). P2X4 receptors induced in spinal microglia gate tactile allodynia after nerve injury. Nature 424, 778-783. 

Morita, K., Kitayama, T., Morioka, N., and Dohi, T. (2008). Glycinergic mediation of tactile allodynia induced by platelet-activating factor (PAF) through glutamate-NO-cyclic GMP signalling in spinal cord in mice. Pain 138, 525—536. 

While a single administration had no effect on pain behavior measured by sensitivity to mechanical stimulation (Fig. 1A), repeated treatment with linalool, 1 h before L5 ligation and then daily for 7 days, attenuated tactile allodynia reaching statistical significance at day 7 (Fig. IB). A prolonged treatment with linalool for up to 14 consecutive days showed similar results and did not ameliorate further hypersensitivity induced by SNL (data not shown). This suggests that... 

Liu, C. N., Wall, R D., Ben-Dor, E., Michaelis, M., Amir, R., and Devor, M. (2000). Tactile allodynia in the absence of C-fiber activation Altered firing properties of DRG neurons following spinal nerve injury. Pain 85, 503-521. 

Chaplan SR, Bach FW, Shafer SL, Yaksh TL 1995 Prolonged alleviation of tactile allodynia by intravenous lidocaine in neuropathic rats. Anesthesiology 83 775-785... 

On the other hand, ethosuximide is a selective T-type Ca " channel blocker [37]. The drug reverses tactile allodynia and thermal hyperalgesia in nerve ligated rats [224],... 

This cytokine has been shown to play a central role in the neuronal reaction following nerve injury. It is closely involved with microglial and astrocytic activation and neuropeptide expression. There is significant information that indicates that IL-6 is intimately connected to the development of neuropathic pain after peripheral nerve injury. Also, intrathecal administration of IL-6 induces tactile allodynia and thermal hyperalgesia in rats. 

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