Establishment of neuropathic pain model by transection of L_4 spinal nerve in rats / 中华麻醉学杂志

ABSTRACT

Objective To establish a neuropathic pain model by transection of L4 spinal nerve in rats.Methods Twenty-eight male SD rats weighing 270-310 g were randomly divided into 3 groups A experimental group (n = 12) received transection of right L4 spinal nerve; B sham operation group ( n = 8) in which right L4 spinal nerve was exposed but not transected and C control group ( n = 8) received no surgery. The paw withdrawal threshold (PWT) to mechanical stimulation was measured by using modified von Frey test. The response to cold stimulation evoked by applying acetone to the plantar region of hindpaw was measured and scored. The threshold to both noxious mechanical and thermal stimuli was measured once a week for 8 weeks. Results In experimental group the pain threshold to mechanical stimuli (von Frey hair stimulation) and cold stimuli (acetone test) on the operated side were significantly decreased after L4 spinal nerve transection as compared to the baseline values before operation and significantly lower than in sham operation and control groups. There was no significant change in the withdrawal response of the hindpaw to mechanical and cold stimuli after surgery on the unoperated side. Conclusion Hyperalgesia to mechanical and cold stimuli develops after L4 spinal nerve transection on the operated side and lasts more than 8 weeks