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.