Strain differences in autotomy levels in mice: relation to spinal excitability

The consequences of combined transection of the sciatic and femoral nerves were investigated in mice of the ICR and C3HEB strains. Whereas all the animals of the C3HEB strain showed very clear self mutilatory behavior of the denervated limb (autotomy) none of the ICR mice showed autotomy. Further tests, using the hot plate and tail flick methods, show that C3HEB mice were more sensitive to noxious thermal stimuli than ICR mice. Finally, spinalization at the lumbar level revealed a markedly higher level of spinal excitability in C3HEB mice as evident from a marked decrease in nociceptive thresholds in these animals. No such threshold decrease was observed in spinalized ICR mice. The results suggest that different levels of spinal excitability underlie the susceptibility for the emergence of autotomy in mice. It is proposed that such different levels of excitability may also underlie the susceptibility for the emergence of neuropathic pain.