Immediate Effects of a Single Exercise on Behavior and Memory in the Early Period of Traumatic Brain Injury in Rats

OBJECTIVE: To evaluate the immediate effect of single exercise on physical performance and memory in the early stage of traumatic brain injury (TBI) in rats. METHODS: Ninety TBI rats were randomly assigned to T0 (sedentary), T10 (treadmill 10 m/min for 30 minutes), or T20 (treadmill 20 m/min for 30 minutes) groups, on day 3 (D3), D7, and D14 after TBI, respectively. Rotarod (RR), Barnes maze (BM), brain magnetic resonance imaging (MRI) and MR spectroscopy were performed immediately before and 6 hours after exercise. Rats were sacrificed for immunohistochemistry with heat shock protein 70 (Hsp70) and glial fibrillary acidic protein (GFAP). RESULTS: On D3, the T10 and T20 groups demonstrated significant improvement in RR (p<0.05). On D7, only the T20 group showed significantly enhanced RR (p<0.05). In BM on D3, the T20 group showed significant deterioration compared with the other groups (p<0.05). Lesion volume did not significantly differ among the groups. MR spectroscopy on D3 showed that only the T20 group had significantly increased choline/creatine and 0.9/creatine (p<0.05). In the perilesional area on D3, only T20 had a significantly higher Hsp70 and GFAP than the T0 group. On D7, Hsp70 was significantly higher in the T20 group than in the T0 group (p<0.05). In the ipsilesional hippocampus on D3, the T20 group showed a significantly higher Hsp70 and GFAP than the T0 group (p<0.05). CONCLUSION: A single session of low-intensity exercise in the early period of TBI improves behavioral performance without inducing cognitive deficits. However, high-intensity exercise can exacerbate cognitive function in the early period after TBI. Therefore, the optimal timing of rehabilitation and exercise intensity are crucial in behavior and memory recovery after TBI.