Correlation Between Parameters Of Diffusion-weight Imaging And JNK1/2 Expression In The Rat Brain Tissue In The Early Of Cerebral Ischemia-reperfusion

Objective: Cerebral ischemia reperfusion injury is an important clinical problem,there are multiple pathological mechanisms involved.Previous studies have shown that mitogen-actived protein kinase(MAPK)pathway plays an important role in cerebral ischemia reperfusion injury,and the c-Jun nterminal kinase(JNK)is an important branch of MAPK.The genes encoding JNK protein include JNK1,JNK2,JNK3.JNK1 and JNK2,which are widely expressed throughout the body,while JNK3 is limited to the brain and heart.Diffusion weighted imaging(DWI)is a sensitive examination for early cerebral ischemia,it can dynamically evaluate the location and progress of cerebral ischemia.Therefore,the correlation between DWI related parameters and JNK1-2 protein expression in the early stage of cerebral ischemia-reperfusion injury is discussed in order to provide a theoretical basis for early clinical intervention.Methods:Forty healthy SD male rats were randomly divided into 4 groups,respectively for cerebral ischemia reperfusion 1d group,1.5d group,3d group and sham group,the experimental groups were made into the model of cerebral ischemic reperfusion injury,then the Longa Zea score was used to evaluate the neurological function of the rats in the experimental groups and sham group.Coronal sections were performed with Philips Achieva 3.0-tesla whole-body MR scanner in the sham group and ischemia reperfusion at different time points.The ADC map was reconstructed on the workstation,and the DWI signal intensity,ADC value and the relative apparent diffusion coefficient(rADC)value of each rat was calculated.Hematoxylin-Eosin(HE)staining was used to observe the morphological changes of different brain tissues.The 2,3,5-Triphenyltetrazolium Chloride(TTC)staining was used to measure the infarct volume.The expression of JNK1-2 protein in brain tissue at different reperfusion time points(1d,1.5d,3d,sham)was determined by immunohistochemistry method.Results:No nerve injury animal in sham operation group,while the neural function of 1d rats 1.5d rats and 3d rats were damaged to varying degrees.There was a significant difference compared with the sham operation group(P<0.05),while there was no significant difference between the nerve function scores of 1d and 1.5d group.the nerve function score of the 3d group is lower than that of 1d and the 1.5d group(P<0.05).After HE staining,the cell structure of the sham operation group was complete,and no obvious destruction was found in the tissue.In the experimental group,the nuclei of the peripheral cortex,the ipsilateral hippocampus,the cerebellum and the medullary cells appeared in the experimental group,and the nuclear condensation and the disorder of the nuclear sequestration were found in the cells of the 1d-3d.TTC staining was not found in sham operation group 1d group white stained area,the infarction area mainly located in the right basal ganglia and frontotemporal cortex,1d-3d infarct size increased,reached peak at 3d,and the 1d-1.5d infarct volume increased significantly,1.5d-3d infarct volume increased slowly.The JNK1-2 protein expression level of the sham operation group is low in the perifocal cortex and ipsilateral hippocampus,cerebellum and medulla,while the positive staining of JNK1-2 cells were showed in the perifocal cortex and ipsilateral hippocampus,cerebellum and medulla of the experimental groups,including 1-1.5d perifocal cortex and ipsilateral hippocampus,cerebellum,average optical density of JNK1-2 mean optical density(MOD)increased gradually with time,reached the peak at 1.5d group,and the 3d group was was lower than the 1.5d group.The 1-3d groups medulla JNK1-2MOD increased gradually with time,and reached the peak at 3d.The expression level of JNK1-2 in the 3 groups were significantly higher than those in sham operation group(P <0.05).There was no abnormal high signal on the DWI image in the sham operation group and the corresponding ADC value was not decreased.The rDWI-SI value of 1-3d cerebral ischemia-reperfusion injury was significantly higher than that of sham operation group,and the corresponding ADC-value was significantly lower than that of sham operation group.The correlation analysis showed that the infarct volume in the 1-3d group was correlated with the JNK1-2 expression in the peripheral cortex,the ipsilateral hippocampus,the cerebellum and the medulla oblongata(P<0.05).There was a time correlation between JNK1-2 expression and ADC value in the ischemic area after reperfusion injury.There was no correlation between the expression of ADC in the cortex and the corresponding ADC value(r=0.184).Conclutions:The high expression of early ischemic perifocal area and distant parts of JNK1-2 were found in cerebral ischemia reperfusion injury,suggesting that JNK1-2 in early cerebral ischemia-reperfusion injury,the application of DWI parameters can well evaluate the cerebral ischemia-reperfusion injury of the temporal dynamics,to provide help for the early diagnosis and treatment of cerebral ischemic injury.