FEMALE RATS ARE MORE SUSCEPTIBLE TO THE DEVELOPMENT OF NEUROPATHIC PAIN USING THE PARTIAL SCIATIC-NERVE LIGATION (PSNL) MODEL

A comparison study was conducted to determine if a gender difference c ould be detected using an animal model for causalgia. The sciatic nerv e was tightly ligated so that 1/3 to 1/2 of the nerve thickness was tr apped by the ligature, just distal to the point at which the posterior biceps semitendinosus nerve branches off the common sciatic nerve. By measuring paw withdrawal from innocuous stimulation with Von Frey fil aments, the percent of rats displaying average mechanical sensitivity of the injured paw that was significantly elevated compared to sham or unoperated control animals (days 22-24) was 28.6% for the male group versus 63.6% for the female group. Our animals did not display a consi stent response in withdrawal latency to heat applied to the plantar su rface of the foot (hyperpathia). The data suggests that female rats ar e significantly more susceptible to developing neuropathic pain than m ale rats using this experimental model for causalgia.