Spinal Nerve Ligation Model
Spinal nerve ligation, also known as the “Chung” model, is currently one of the most frequently used models for nerve injury and neuropathic pain behavior in animals (rats/mice; Kim and Chung, 1992). The lumbar 5 spinal nerve is ligated with silk suture just distal to the L5 DRG. Usually, the spinal nerve is then cut just distal to the ligation. In some cases, the lumbar 6 spinal nerve is also ligated and cut. In non-injured animals, the distal axons of L4 and L5 neurons comingle in the sciatic nerve and innervate overlapping territories in the skin. After L5 spinal nerve ligation, the distal axons of the L5 nerve degenerate within the sciatic nerve. It is thought that inflammatory and immune processes involved in the degeneration of the distal L5 fibers then affect the adjacent “uninjured” L4 nerve fibers, causing functional changes in the L4 neurons. The advantage of this model, compared to other nerve injury models, is that all L5 DRG neurons...