Background

Partial nerve injury animal models have been developed for the purpose of studying the molecular, cellular, and circuit mechanisms of neuropathic pain (Bennett and Xie, 1988; Seltzer et al., 1990; Kim and Chung, 1992). A partial denervation model enables researchers to investigate structural and functional changes in diverse groups of neuronal and non-neuronal cells. Studies can be performed during the initiation, progression (also known as acute) and maintenance (chronic) phases of neuropathic pain, as well as at different anatomical sites along the pain pathway including distal vs. proximal peripheral nerve fibers, dorsal root ganglion, spinal cord, subcortical and cortical areas. The spared nerve injury (SNI) model involves partial nerve injury where the common peroneal and tibial nerves are injured, producing consistent and reproducible pain hypersensitivity in the territory of the spared sural nerve (Decosterd and Woolf, 2000; Shields et al., 2003). This model has proved to be robust, demonstrating substantial and prolonged changes in behavioral measures of mechanical sensitivity and thermal responsiveness (Bourquin et al., 2006). These features closely mimic the cardinal symptoms of clinically described neuropathic pain disorders.