The purpose of this study is to examine the recovery process of a mouse model of intracerebral hemorrhage (ICH) subjected to different exercise intensities. In addition, we will examine the lactate levels of the mice as an indicator of exercise intensity control.
ICH was induced by collagenase injection. Four grouped male mice (Sedentary（Sed）, voluntary exercise（V-Ex）, low-intensity forced exercise（LF-Ex）, high-intensity forced exercise（HF-Ex）) were exercised by running wheel. Exercise was performed from 4 to 28 days after surgery. Exercise intensity was defined by blood lactate level, with 5m/min of running speed as low, 8m/min as high intensity. Motor function was evaluated using rotarod test, beam walk test, and horizontal ladder test. Behavioral tests were performed immediately before and one day after surgery, and then every 3-4 days thereafter. The plasma corticosterone level was measured on 14 and 28 days after surgery to evaluate the stress level.
Animals in all groups showed a marked decrease in motor function at first day after surgery, and recovery of motor function up to 10 days after surgery. The V-Ex and the LF-Ex showed motor function recovery from 14 days after surgery, while the HF-Ex showed motor function decline or slowdown. The scores of motor function were higher in the V-Ex than in the Sed and the HF-Ex from 10 days after surgery. The V-Ex group showed earlier recovery of motor function in the beam walk test (hindlimb coordination assessment) and horizontal ladder test (forelimb coordination assessment) than in the rotarod test (whole-body coordination assessment) in the Sed. The corticosterone concentrations in the LF-Ex and the HF-Ex were higher than the Sed at 14, 28 days after surgery.
These results indicate that the V-Ex was more effective than the LF-Ex and the HF-Ex for functional recovery after ICH. Based on the stress evaluation, the LF-Ex and the HF-Ex groups, which have a higher stress than the Sed, may have impaired motor function recovery. Although lactate levels in the V-Ex were not measured, the V-Ex had a lower exercise intensity and more moderate stress level than the LF-Ex, and it is thought that the appropriately controlled exercise promoted recovery of motor function.
Our results suggest that mismanagement of exercise intensity may induced stress and delay motor recovery after ICH. Measurement of exercise intensity using lactate level for animal models may contribute to setting appropriate exercise intensity in the clinical environment.
stress
exercise intensity
