The Effects of Exercise Preconditioning on Cerebral Blood Flow Change and Endothelin-1 Expression after Cerebral Ischemia in Rats

Stroke is an acute cerebrovascular disease with high incidence, morbidity, and mortality. Preischemic treadmill training has been shown to be effective in improving behavioral and neuropathologic indices after cerebral ischemia. However, the exact neuroprotective mechanism of preischemic treadmill training against ischemic injury has not been elucidated clearly. The present study investigated whether preischemic treadmill training could protect the brain from ischemic injury via regulating cerebral blood flow (CBF) and endothelin 1 (ET-1). We analyzed the CBF by laser speckle imaging and ET-1 expression by an enzyme-linked immunosorbent assay using an ischemic rat model with preischemic treadmill training. Generally speaking, ET-1 expression decreased and CBF increased significantly in the pretreadmill group. It is worth noting that ET-1 expression is increased at 24 hours of reperfusion in the pretreadmill group compared with the level of the time after middle cerebral artery occlusion. These changes were followed by significant changes in neurologic deficits and cerebral infarct volume. This study indicated that preconditioning exercise protected brain from ischemic injury through the improvement of CBF and regulation of ET-1 expression, which may be a novel component of the neuroprotective mechanism of preischemic treadmill training against brain injury.