Zhihong Cheng,1,* Song Feng,1,2,* Linfeng Yang,1 Jing Huang,3 Xilei Chen,4 Yang Guo,1 Yu Xiang,1 Bin Peng1 

1Institute of Basic Medicine and Forensic Medicine, North Sichuan Medical College, Nanchong, Sichuan, People’s Republic of China; 2Department of Neurosurgery, Dazhou Third People’s Hospital, Dazhou, Sichuan, People’s Republic of China; 3Innovation Center for Science and Technology, North Sichuan Medical College, Nanchong, Sichuan, People’s Republic of China; 4Department of Clinical Medicine, North Sichuan Medical College, Nanchong, Sichuan, People’s Republic of China

*These authors contributed equally to this work

Correspondence: Bin Peng, Institute of Basic Medicine and Forensic Medicine, North Sichuan Medical College, No. 234 Fujiang Road, Shunqing District, Nanchong, Sichuan, People’s Republic of China, Tel/Fax +86-817-2242781, Email binpeng01@sina.com

Purpose: The spinal nerve ligation (SNL) model is a typical peripheral neuropathic pain model. During its construction, the removal of paraspinal muscles and transverse processes typically occurs, resulting in additional trauma that may potentially affect the pathophysiologic process of neuropathic pain. This study aimed to investigate the feasibility of establishing a more reliable SNL model using an oblique lateral approach.
Methods: 36 adult male Sprague-Dawley rats were randomly divided into three groups: the traditional SNL (T-SNL) group, the new SNL (N-SNL) group (where the left L5 spinal nerve was ligated with a titanium clip via an oblique lateral approach), and the sham-operated (Sham) group. The operation time, Intraoperative bleeding, the number of rats that died, gait behavior, mechanical and cold pain threshold were recorded and measured. Stereology technology was used to calculate the number of microglia in spinal dorsal horn, and the Enzyme-linked immunosorbent assay (ELISA) technology was used to detect the expression of TNF-α and IL-1β in spinal cord as well as C-reactive protein (CRP) in serum in order to assess the effect of surgery on animal inflammation.
Results: Compared with the T-SNL group, operative time and intraoperative bleeding were significantly decreased in the N-SNL group. Within 14 days postoperation, one rat in the N-SNL group was died, two rats in the T-SNL group were died. Compared with the Sham group, the N-SNL group showed obvious spontaneous pain behavior, decreased the pain thresholds, the number of microglia and the expression of TNF-α and IL-1β were significantly increased, and there was no significant difference in these indexes compared with T-SNL group. There was no significant difference in serum CRP levels among the three groups.
Conclusion: This study suggests that the oblique lateral approach SNL model is a reliable NP model with the advantages of good reproducibility, accessibility, and low trauma.

Keywords: animal model, mechanical pain threshold, hyperpathia, microglial, peripheral nerve injury, inflammatory