Phen reverses mTBI-induced neuronal loss in WT and APP/PSEN1 mice. Degenerating neuronal cells were quantified using the marker Fluorojade C (FJC: green). (A) An increased number of FJC+ cells were observed in vehicle administered mTBI (mTBI-VEH) vs. sham control (CTRL) WT mice across the hippocampus (CA1, CA3 and DG) and cerebral cortex (***p < .001, ****p < .0001 vs. CTRL by Tukey’s post hoc test). (B) A similar elevation was induced by mTBI in APP/PSEN1 vehicle administered mice that reached significance in the hippocampus (#p < .05 vs CTRL by Mann-Whitney rank test in CA1). Post treatment with Phen abated the neuronal loss, in which FJC+ cell counts were no different from values of sham control (CTRL) mice. Importantly in WT animals, values in the Phen 5 mg/kg group were significantly lower than the mTBI vehicle group (^^p < .01, ^^^p < .001 vs. mTBI by Tukey’s post hoc test). Representative images and graphs from hippocampus and cortex. Data shown as mean ± S.E.M. Scale bar = 30 μm.