Beyond rodent models of pain: non-human primate models for evaluating novel analgesic therapeutics and elaborating pain mechanisms.

Evaluation of potential analgesic therapeutics and the elaboration of the neurobiology of pain have heavily relied on pain models developed in rodents. However, a limitation of rodents is their phylogenetic distance from humans, which could in part account for the failure of some preclinical findings to translate to clinical utility. By contrast, given their genetic closeness and phenotypic similarities to humans, it is suggested that there be greater utilization of non-human primates (NHP) in preclinical pain studies. Methods to induce chronic pain-like states and quantify changes in nociception that have been developed in rodents could be adapted to the NHP. Similarly, human experimental injury-induced sensitization, which attempts to temporarily mimic the neuropathology and symptoms observed in the chronic pain state, could be adapted to the NHP. The NHP could then serve as a platform to validate human experimental models as well as proof-of-concept studies. Beyond experimentally modeled pain states, a number of naturally occurring disease states, such as osteoarthritis, are expressed by NHP, which could be utilized for both hypothesis testing and proof-of-concept studies. While NHP studies are logistically cumbersome, it is envisioned that NHP pain models will add value to current preclinical data and greatly facilitate the discovery of novel analgesic treatments.