Possible role of sympathetic activity in abnormal behavior of rats induced by lesion of the sciatic nerve.

The role of genetic differences and environmental stress in the form of continuous exposure to cold in the production of abnormal behavior in rats was examined by subjecting the animals to unilateral sciatic nerve section. Some nerve-lesioned Sprague-Dawley (SD) rats responded to the cold by developing a state we termed stress-related pain behavior (SRPB). These animals also self-mutilated the denervated limb (autotomized) more often than cold-exposed rats that did not develop SRPB. The role of genetic differences was studied by also subjecting Wistar-Kyoto (WK) and spontaneously hypertensive (SHR) rats to sciatic nerve section and cold. Both WK and SHR rats, which have a higher level of circulating catecholamines than SD rats, autotomized significantly less than SDs, and did not exhibit SRPB. The results suggest that differences in susceptibility to stress and genetic variability may be important factors in the development of abnormal and/or pain behaviors following peripheral nerve trauma.