Injury of Muscular but not Cutaneous Nerve Drives Acute Neuropathic Pain in Rats
Acute pain is a common complication after injury of a peripheral nerve but the underlying mechanism is obscure. We established a model of acute neuropathic pain via pulling a pre-implanted suture loop to transect a peripheral nerve in awake rats. The tibial (both muscular and cutaneous), gastrocnemius–soleus (muscular only), and sural nerves (cutaneous only) were each transected. Transection of the tibial and gastrocnemius–soleus nerves, but not the sural nerve immediately evoked spontaneous pain and mechanical allodynia in the skin territories innervated by the adjacent intact nerves. Evans blue extravasation and cutaneous temperature of the intact skin territory were also significantly increased. In vivo electrophysiological recordings revealed that injury of a muscular nerve induced mechanical hypersensitivity and spontaneous activity in the nociceptive C-neurons in adjacent intact nerves. Our results indicate that injury of a muscular nerve, but not a cutaneous nerve, drives acute neuropathic pain.
KeywordsMuscular nerve Cutaneous nerve Acute neuropathic pain
We thank Bo Yuan, B.S., Tao Wang, Ph.D. and Jin Tao, M.S. from the Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, Beijing, China, for technical assistance. This work was supported by grants from the National Natural Science Foundation of China (NSFC; 81271239 and 91632113 to CM, and NSFC for Young Scientists 81600956 to WD), and the Chinese Academy of Medical Sciences Innovation Fund for Medical Sciences (2017-I2M-3-008 to CM).
Conflict of interest
The authors claim that there are no conflicts of interest.