The Study On The Neuroprotection Of Pre-ischemic Enriched Environment For Cerebral Ischemia/Reperfusion Injury

Objective:In China, the ischemic stroke is associated with high morbidity, lethality and disability rate. Enriched environment has been demonstrated to be neuroprotective but the mechanism is still not clear. Our study aimed to investigate whether pre-ischemic enriched environment could serve as a form of ischemic preconditioning in a rat model undergoing middle cerebral artery occlusion (MCAO)/reperfusion (R) and to exam whether voluntary exercise may involve in the neuroprotective effect of enriched environment.Methods:Seventy-two Sprague Dawley (SD) rats were divided into three groups: a sham control group, a MCAO group (in fact, this is short for MCAO/R group) with standard condition and a MCAO (in fact, this is short for MCAO/R group) with enriched environment. During4weeks’rearing in different condition, we recorded the exercise level of all the rats daily. Cerebral ischemia was induced via middle cerebral artery occlusion for2hours, followed by reperfusion. Six rats in each group were evaluated for neurological deficits by behavioral scoring, rota-rod test, cylinder test, foot fault test and morris water maze. Another Six rats in each group were decapitated to assess the infarct volume by TTC method5days after reperfusion. The remaining animals were sacrificed to detect the difference of brain edema by measuring water content.Results:Compared to the MCAO group with standard condition, the enriched environment promoted the level of voluntary exercise, demonstrated by such four exercise-related parameters as distance moved, velocity, mobile duration, moving duration (P<0.05). Five days after reperfusion, pre-MCAO EE significantly reduced brain infarct size relative to MCAO with standard condition (P<0.05). Similarly, pre-MCAO EE significantly reduced neurological defects relative to MCAO with standard condition (P<0.05). Meanwhile, pre-MCAO exercise significantly reduced brain edema relative to MCAO with standard condition (P<0.05).Conclusions:This study suggests that pre-ischemic enriched environment might induce neuroprotection by promoted the level of voluntary exercise, decreasing the cerebral infarction, alleviating the brain edema and mitigating the neurological defects. The results indicate that enriched environment might be an potential method to establish ischemic preconditioning. The study on the regulation of enriched environment for cortical blood supply after cerebral ischemia/reperfusion injuryObjective:as a important conception in neuroscience,’neurovascular unit’ is well known in this field. Enriched environment, which has long been demonstrated to be neuroprotective, is considered to be of angiogenesis. However, it is still not clear whether the enriched environment-induced angiogenesis can finally rebuild the cortical blood supply in ischemic area. Our study aimed to investigate whether enriched environment can induce reconstruction of cortical blood supply in ischemic area.Methods:Thirty-six Sprague Dawley (SD) rats were divided into three groups:a sham control group, a MCAO group with standard condition(SC group) and a MCAO with enriched environment(EE group) after cerebral ischemia was induced via middele cerebral artery occlusion for2hours, followed by reperfusion. Rats then had been reared for4weeks in such experimental environments as enriched environment and standard housing condition. Cerebral blood flow (CBF) of rats in each group was recorded by laser speckle imaging (LSI) before,1hour after and4weeks after MCAO.Results:1hour after ischemia, mean CBF was reduced significantly in both SC (P<0.01) and EE group (P<0.01) and remain stable in sham group. After4-week environmental manipulation, mean CBF was significantly higher in EE group compared to SC group (P<0.05)Conclusions:This study suggests that EE be more applicable in the aspect of CBF recovery level after MCAO. This might be one of brain protective ways induced byEE.