Study On The Mechanism Of Juvenile Ischemic Stroke

Stroke,called "zhongfeng" in Traditional Chinese Medicine,has become one of the diseases that seriously endanger the health and life of human because of its high lethality,disability and morbidity.In recent years,the incidence of children ischemic stroke(CIS)has been increasing year by year.Therefore,we must change our past minds,raise the awareness of ischemic stroke in children,and strengthen research and prevention of cerebrovascular diseases in children.Previous studies have shown that young animals have stronger recovery and resistance to ischemic stroke than adult animals,but the specific mechanism is not yet clear.Therefore,this experiment will be through the model of middle cerebral artery occlusion(MCAO)and transient cerebral ischemia stroke to explore the mechanism of young animal ischemic stroke.Part ? Study on the relationship between brain injury and changes of autophagy-associated protein caused by focal ischemia-reperfusion in youngOBJECTIVE:To explore the regulatory mechanisms of autophagy-mediated signaling pathways on neuronal injury induced by cerebral ischemic injury in young rats and to provide therapeutic targets for adult ischemic stroke.METHODS:MCAO model was used in this experiment.The experiment consisted of a young group(1 month old Sprague Dawley(SD)rats;n=120)and an adult group(6 month old;n=120).In the two groups were randomly divided into sham group(n = 60)and surgery group(n = 60),ischemia/reperfusion surgery(infarct time is divided into 30min,60min,90min).Experimental animals was executed in the following the time(1 day,3 days;n=30)and the brain tissue was taken for backup.Neurological function scores and TTC staining were used to observe the differences in neurological function and infarct volume after young and adult rats ischemia reperfusion.Immunohistochemical staining was used to observe the expression of immunoreactive NeuN,GFAP and IBA-1 in the penumbra region of young and adult rats after ischemia reperfusion.Immunofluorescence double staining was used to observe the changes of the Beclin-1 and NeuN in the penumbra after ischemia reperfusion and the co-staining conditions.Western blot was used to observe the expression of autophagy and apoptosis-related expression in the penumbra region of young and adult rats after ischemia reperfusion.Results:1.the neurological score and infarct volume in young rats were smaller than those in adult rats in different infarction and reperfusion time.With the prolongation of ischemic or reperfusion time,the immunoreactivity of NeuN gradually decreased in young and adult rats,but the expression of NeuN in young rats was significantly higher than that in adult rats under different conditions.3.With the extension of reperfusion time,the degree of glial activation is greater,but the glial activation in infarct penumbra area of young rats were significantly lower than that in adult rats.4.Immunohistochemical expression of Beclin-1 in the infarct penumbra of young rats was significantly increased and co-expressed with neurons.However,the expression of Beclin-1 in the infarct penumbra of adult rats did not change significantly.5.The levels of autophagy-related proteins in the infarcted penumbra were significantly increased after ischemia reperfusion,but the increase was more pronounced in young rats than those in adult rats.After ischemia reperfusion,the apoptosis-related factors in young rats were significantly lower than those in adult rats,but the anti-apoptosis-related proteins were significantly higher than those in adult rats.Conclusion:After focal ischemic stroke,the decrease of infarct volume and neuronal death in young rats was closely related to its elevation and maintenance of the level of neuronal autophagy and regulation of related apoptotic factors.Part ? Study on the relationship between neurological injury and changes of the expression of IGF1 and its receptor induced by global ischemia-reperfusion in youngObjective:To observe the changes of IGF1 and IGF1R expression in hippocampal CA1 region of young gerbils after transient cerebral ischemia stroke(TCI)and observe the differences between young and adult gerbils.Then to determine change of the IGF1 and IGF1R expression were related with the delay of neural cell death in young gerbils.METHODS:We used the TCI model,transient isolating bilateral common carotid artery occlusion resulting in reduced blood supply to the brain causing ischemic injury,in this experiment.The experiment consisted of a young group(1 month old gerbils;n=60)and an adult group(6 months old gerbils;n=60),which were randomly divided into sham groups(n=30)and the surgery group(n=30)within the two groups.The experimental animals were sacrificed according to the following chronological order(1 day,4 days,7 days;n=10)and the brain tissue was taken for use.Immunohistochemical staining was used to observe the number of neuronal death and the changes of IGF1 and IGF1R immunoreactivity in hippocampal CA1 region after cerebral ischemia reperfusion.The protein and RNA levels of IGF 1 and IGF 1R in the hippocampus of gerbils were determined by Western blotting and RT-PCR.The changes of PI3K/Akt pathway proteins were also observed by Western blotting.Results:1.Young gerbils delayed the time of neuronal cell death in hippocampal CA1 and also reduced the number of neuronal death.2.Under normal conditions,the immunoreactivity,protein level and RNA level of IGF1 and IGF1R in the brain of young gerbils are higher than that in adult gerbils.The young gerbils maintained the expression of IGF 1 and IGF1R,delaying the time of expression decrease after ischemia reperfusion.3.The levels of PI-3K and akt/p-akt protein in the hippocampus of young gerbils decreased after ischemia-reperfusion,but the overall level was higher than that in adult gerbils.CONCLUSION:After TCI,the young gerbils postponed neuronal death and decreased neuronal death in the hippocampal CA1 region by maintaining the expression levels of IGF 1 and IGF1R in the hippocampal CA1 region.Therefore,IGF1 and IGF1R may become the therapeutic targets for the prevention of cerebral ischemic injury.