Behavioral responses of C57BL/6, FVB/N, and 129/SvEMS mouse strains to traumatic brain injury: Implications for gene targeting approaches to neurotrauma

Recent studies have suggested that mouse models of traumatic brain injury m ay be useful for evaluating the role of single gene products in brain traum a. In the present study, we report that three background strains (C57BL/6, FVB/N, and 129/SvEMS), commonly used in genetically altered mice, exhibit s ignificantly different behavioral responses when subjected to sham surgery (n = 9 per group) or moderate controlled cortical impact (CCI) injury (n = 12 per group), Injured animals from all three strains showed delayed recove ry of pedal withdrawal and righting reflexes compared to sham-operated cont rols. Significant deficits in both a forepaw contraflexion and rotarod task were evident for up to 7 days after injury, with no significant difference among strains. Sham-operated C57BL/6 mice performed significantly better t han FVB/N and 129/SvEMS sham controls in a beam walking task up to 4 weeks after surgery, However, CCI-injured FVB/N mice outperformed injured animals from both other strains in this same task, Significant impairment of place learning in the Morris water maze and Barnes circular maze was observed at 7-10 days and 21-24 days after injury, respectively, in C57BL/6 mice when compared with sham controls. Sham-operated FVB/N and 129/SvEMS mice were un able to learn either task, and performance did not differ significantly fro m respective CCI injured animals. Our results suggest that background strai n should be carefully considered with experiments involving genetically alt ered mice, especially when planning behavioral outcome measures after CNS i njury.