The development of a repetitive mild traumatic brain injury model in adolescent mice

Abstract

While participation in youth sports bolster a myriad of health benefits, it can also pose a risk to the athlete's health from the increasing prevalence of repetitive mild traumatic brain injuries (TBI), often referred to as concussions. The adverse effects from repeated traumatic blows give a combination of acute symptoms, which may potentially develop into long-term complications. There is little known about the epidemiology of concussions, and thus the development of an animal model would help enhance our understanding of this potentially debilitating injury. An appropriate animal model should mimic the conditions of how concussions occur, in that there is not an invasive method to induce the injury and follows the same biomechanics. In our adolescent repetitive mild TBI model, we utilized a free-falling weight to deliver the traumatic blow to anesthetized mice that allowed free head rotation after impact. The injured group received one hit daily over the course of three days. The mice then underwent several behavioral tests to analyze the cognitive deficits, and the pathology of the tissue was analyzed via silver, Hematoxylin and Eosin (H&E), and Fluoro Jade-B staining. The injured mice developed both short- and long-term memory and spatial learning deficits, symptoms commonly found in concussed athletes, but failed to show deficits in anxiety and depression tests. The Fluoro Jade-B, silver and H&E staining resulted in negative signals for cell death. This study properly demonstrates repetitive mild TBIs in an adolescent mice model.