Models of neuropathic pain in the rat.

Peripheral nerve injury due to trauma, disease, and certain toxins sometimes produces abnormal (neuropathic) pain syndromes that are chronic and refractory to standard analgesics. Knowledge of the mechanisms that produce neuropathic pain and the ability to search for new drugs to control it have been greatly advanced by the introduction of rat models of post-traumatic painful peripheral neuropathy. There are currently three models of neuropathic pain in the rat that are widely used. The procedures to create these models and the behavioral assays used to quantify the resulting neuropathic pain symptoms are described in this unit: the chronic constriction injury (CCI) model, the partial sciatic ligation (PSL) model, and the spinal nerve ligation (SNL) model. Four kinds of abnormal pain sensations are commonly measured to assess the outcome: heat-hyperalgesia, mechano-hyperalgesia, mechano-allodynia, and cold-allodynia.