1 Institute of Neuroscience, Fourth Military Medical University, Xi抋n 710032, China 
2 Class 2006, School of Aerospace Medicine, Fourth Military Medical University, Xi’an 710032, China 
3 Department of Anesthesiology, The Second Affiliated Hospital of Wenzhou Medical College, Wenzhou 325027, China

Abstract 

Objective
Low back pain is one of the most inextricable problems encountered in clinics. Animal models that imitate symptoms in humans are valuable tools for investigating low back pain mechanisms and the possible therapeutic applications. With the development of genetic technology in pain field, the possibility of mutating specific genes in mice has provided a potent tool for investigating the specific mechanisms of pain. The aim of the present study was to develop a mouse model of chronic compression of dorsal root ganglion (CCD), in which gene mutation can be applied to facilitate the studies of chronic pain.
Methods
Chronic compression of L4 and L5 dorsal root ganglia was conducted in mice by inserting one stainless steel rods into the intervertebral foramina, one at L4 and the other at L5. Mechanical allodynia and thermal hyperalgesia were examined with von Frey filaments and radiating heat stimulator, respectively.
Results
The CCD mice displayed dramatic mechanical and thermal hyperalgesia as well as tactile allodynia in the hindpaw ipsilateral to CCD. In addition, this mechanical and thermal hyperalgesia as well as tactile allodynia was also found to spread to the contralateral hindpaw.
Conclusion
This model, combined with the possible genetic modification, will strengthen our knowledge of the underlying mechanisms of low back pain. It also favors the development of new treatment strategies for pain and hyperalgesia after spinal injury and other disorders which affect the dorsal root ganglion in humans.

Keywords

chronic compression of dorsal root ganglion; mice; hyperalgesia; allodynia

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