Genetic factors may influence the development of spinal reflex hyperexcitability following sciatic nerve section in the rat.

We compared changes in the excitability of the hamstring flexor reflex evoked by electrical stimulation of the sciatic nerve before and after section of the peroneal, tibial and sural branches of the nerve in Sprague-Dawley (SD) and spontaneously hypertensive (SHR) rats. In both rat strains, the flexor reflex exhibited a biphasic hyperexcitability lasting over 120 min after nerve section. The initial brief, intense increase in reflex excitability was similar in SD and SHR rats. The second prolonged phase, which may represent hyperalgesia, was significantly greater in SHR than SD rats. These results indicate that genetic differences may have a role in the development of central sensitization.