Minocycline improves cognition and molecular measures of inflammation and neurodegeneration following repetitive mTBI

Objective: To compare the neuroprotective effects of minocycline treatment in a murine model of mTBI on measures of spatial learning and memory, neuroinflammation, excitotoxicity, and neurodegeneration. Design: Adult male C57BL/6 J mice were randomly assigned into vehicle control, vehicle with repetitive mTBI, minocycline without mTBI, or minocycline with repetitive mTBI groups. Methods: A validated mouse model of repetitive impact-induced rotational acceleration was used to deliver 15 mTBIs across 23 days. Cognition was assessed via Morris water maze (MWM) testing, and mRNA analysis investigated MAPT, GFAP, AIF1, GRIA1, TARDBP, TNF, and NEFL genes. Assessment was undertaken 48 h and 3 months following final mTBI. Results: In the chronic phase of recovery, MWM testing revealed impairment in the vehicle mTBI group compared to unimpacted controls (p < .01) that was not present in the minocycline mTBI group, indicating chronic neuroprotection. mRNA analysis revealed AIF1 elevation in the acute cortex (p < .01) and chronic hippocampus (p < .01) of the vehicle mTBI group, with minocycline treatment leading to improved markers of microglial activation and inflammation in the chronic stage of recovery. Conclusions: These data suggest that minocycline treatment alleviated some mTBI pathophysiology and clinical features at chronic time-points.