Developing a model of temporomandibular disorder in the common marmoset using nerve growth factor

Developing an animal model that more closely represents the human multidimensional pain experience is an important step toward addressing the current chronic pain crisis. The common marmoset has potential as a model species, given its biological, neurological, and phylogenetic similarity to humans. Here, we developed a model of myofascial temporomandibular disorder (TMD) in the marmoset by injecting nerve growth factor (NGF) into the superficial masseter. Following injection, animals showed reduced mechanical withdrawal thresholds at 5 μg and 10 μg doses of NGF and changes in circadian rhythm and feeding initiation following injection of 10 μg of NGF. Animals did not show evidence of other TMD-related pain behaviors, including jaw dysfunction, masticatory alterations, or grimace during novel behavioral assays. The model is transient, with pain resolution occurring approximately 7 days after onset, which allows for repeated testing on the same animal. This same NGF-TMD model has been previously validated in rodents and humans and presents an opportunity for forward and reverse translation to examine mechanisms, develop relevant pain assessment tools, and ultimately test novel treatments for TMD and other musculoskeletal pain conditions.<b>NEW & NOTEWORTHY</b> We developed a long-lasting but transient (∼7 days) model of myofascial temporomandibular disorder (TMD) pain in marmosets. Mechanical hypersensitivity and changes to circadian activity and spontaneous eating behaviors were observed. There was no evidence of jaw dysfunction, altered food preference, or changes in grimace. The nerve growth factor (NGF)-TMD model can be translated to the marmoset with the potential for investigating mechanisms and novel interventions for TMD.