Axonotmesis-evoked plantar vasodilatation as a novel assessment of C-fiber afferent function after sciatic nerve injury in rats
Xue-Song Wang1, Xue Chen2, Tian-Wen Gu3, Ya-Xian Wang3, Da-Guo Mi MD 4, Wen Hu MD, PhD 3
1 Department of Orthopedics, The Affiliated Hospital of Jiangnan University (The Third People's Hospital of Wuxi City), Wuxi, Jiangsu Province, China
2 Wuxi School of Medicine, Jiangnan University, Wuxi, Jiangsu Province, China
3 Key Laboratory for Neuroregeneration of Ministry of Education and Co-innovation Center for Neuroregeneration of Jiangsu Province, Nantong University, Nantong, Jiangsu Province, China
4 Department of Orthopedics, Nantong Hospital of Traditional Chinese Medicine, Nantong, Jiangsu Province, China
Department of Orthopedics, Nantong Hospital of Traditional Chinese Medicine, Nantong, Jiangsu Province
Key Laboratory for Neuroregeneration of Ministry of Education and Co-innovation Center for Neuroregeneration of Jiangsu Province, Nantong University, Nantong, Jiangsu Province, China
Source of Support: This work was supported in part by the National Natural Science Foundation of China, No. 81100939 and 81773713 (to WH), No.
81501610 (to XC); the Research Project funded by Jiangsu Provincial Government of China, No. BRA2018223 (to DGM); the Public Health Center
at Jiangnan University of China, No. JUPH201808 (to XSW); the Wuxi Commission of Public Health and Family Planning of China, No. MS201717
(to XSW); the Project of Academic Development Program by Governments of Jiangsu Province and Nantong City of China (to DGM), Conflict of Interest: None
Quantitative assessment of the recovery of nerve function, especially sensory and autonomic nerve function, remains a challenge in the field of nerve regeneration research. We previously found that neural control of vasomotor activity could be potentially harnessed to evaluate nerve function. In the present study, five different models of left sciatic nerve injury in rats were established: nerve crush injury, nerve transection/suturing, nerve defect/autografting, nerve defect/conduit repair, and nerve defect/non-regeneration. Laser Doppler perfusion imaging was used to analyze blood perfusion of the hind feet. The toe pinch test and walking track analysis were used to assess sensory and motor functions of the rat hind limb, respectively. Transmission electron microscopy was used to observe the density of unmyelinated axons in the injured sciatic nerve. Our results showed that axonotmesis-evoked vasodilatation in the foot 6 months after nerve injury/repair recovered to normal levels in the nerve crush injury group and partially in the other three repair groups; whereas the nerve defect/non-regeneration group exhibited no recovery in vasodilatation. Furthermore, the recovery index of axonotmesis-evoked vasodilatation was positively correlated with toe pinch reflex scores and the density of unmyelinated nerve fibers in the regenerated nerve. As C-fiber afferents are predominantly responsible for dilatation of the superficial vasculature in the glabrous skin in rats, the present findings indicate that axonotmesis-evoked vasodilatation can be used as a novel way to assess C-afferent function recovery after peripheral nerve injury. This study was approved by the Ethics Committee for Laboratory Animals of Nantong University of China (approval No. 20130410-006) on April 10, 2013.