Role of Nogo Receptor-1 for Recovery of Balance, Cognition, and Emotion after Mild Traumatic Brain Injury in Mice.

Mild traumatic brain injury (mTBI) constitutes 75 ∼ 90% of all TBI cases and causes various physical, cognitive, emotional, and other psychological symptoms. Nogo receptor 1 (NgR1) is a regulator of structural brain plasticity during development and in adulthood. Here, we used mice that, in the absence of doxycycline, overexpress NgR1 in forebrain neurons (MemoFlex) to determine the role of NgR1 in recovery from mTBI with respect to balance, cognition, memory, and emotion. We compared wild-type (WT), MemoFlex, and MemoFlex + doxycycline mice to the same three groups subjected to mTBI. mTBI was induced by a controlled 30-g weight drop. We found that inability to downregulate NgR1 significantly impairs recovery from mTBI-induced impairments. When the NgR1 transgene was turned off, recovery was similar to that of WT mice. The results suggest that the ability to regulate NgR1 signaling is needed for optimal recovery of motor coordination and balance, spatial memory, cognition, and emotional functions after mTBI.