Mechanism Of Chest Blast Injury On Early Brain Cognitive Dysfunction Injury

Objective: Establishing an animal model of chest blast injury in mice,the characteristics and mechanism of brain cognitive dysfunction caused by chest blast injury were studied,and the effects of blood-brain barrier injury and oxidative stress on brain cognitive injury were discussed.Methods: 1.Group: 60 clean-grade male C57BL/6 mice(8 weeks)were randomly divided into the control group mice and experimental group mice(DAY1 group,DAY3 group,and DAY7 group).2.The mouse of chest blast brain injury was established: the compressed air under the blast injury device broke through the airtight space of aluminum foil to release a shock wave.The mice were weighed,anesthetized,and then exposed to the chest making the model of blast injury.3.Neurological assessment: motor and behavioral defects were assessed by Toklu score,and spatial memory ability was measured by Morris maze.4. Sampling and detection: the frontal lobe,occipital lobe,and hippocampus of mice were collected and placed in tissue fixation solution and liquid nitrogen,respectively,and then stored to the-80℃ refrigerator.HE was used to detect brain tissue in different regions.Evans blue was used to observe the permeability of the blood-brain barrier.Detection kit and Western blot were used to detect oxidative stress injury.Results: There was a significant difference in the Toklu test between the control and experimental groups(F=10.40,P=0.004).The neurological score of DAY1 group mice was significantly higher than in others.There was a significant difference in the overall latency distribution among the four groups in the Morris maze test(H=15.303,P=0.002).Compared with the control group mice,the latencies of the DAY1 group mice and DAY3 group mice were significantly increased(P=0.006,P=0.003).The results of pathological HE showed that the pyramidal cells in the experimental group’s frontal cortex,occipital cortex,and hippocampus were stained deeply,and the signs of nuclear vacuolation and nuclear contraction were unclear.The number of cytoplasmic eosinophils increased in the hippocampus.The results of western blot showed that the result of P-Tau/Tau in the DAY1 group and DAY3 group mice was significantly increased(P<0.05).The result of P-Tau/Tau in the occipital cortex was significantly increased in DAY1 and DAY3 groups mice(P<0.05).The result of P-Tau/Tau in the hippocampus of all experimental groups was significantly increased compared with the control group mice(P<0.05).The permeability of the blood-brain barrier was evaluated by Evans blue staining.In different brain regions,there were significant differences between the experimental and control groups mice in the frontal lobe(P<0.01).In the occipital lobe and hippocampus of DAY7 group mice,there was a significant difference with the control group mice(P<0.01).In the different groups,there was a significant difference between the frontal lobe and the occipital lobe and the hippocampus in the DAY1 group mice(P<0.01).However,there was no significant difference between the occipital lobe and the hippocampus(P>0.05).There was an extraordinary difference among the frontal lobe,occipital lobe and hippocampus of the DAY3 group mice(P<0.01).There was no significant difference among the frontal cortex,occipital cortex,and hippocampus in DAY7 group mice(P>0.05).The ROS results showed a significant difference between the DAY3 group mice and the control group mice(P<0.05).ROS expression was significantly different between the frontal lobe,occipital cortex and hippocampus(P<0.05).DAY7 group mice compared with the control group,there was a statistical difference(P<0.05),and there were significant differences among the frontal cortex and occipital cortex,hippocampus(P<0.05).There was no significant difference among the frontal lobe,occipital lobe and hippocampus in the DAY7 group mice.Western blot showed that the expression of SOD2 in the frontal cortex was significantly decreased in the DAY1 group mice.In contrast,the expression of COX2 in the experimental group mice was significantly increased.The expression of SOD2 in the occipital cortex decreased significantly in the DAY7 group mice,and the expression of COX2 increased significantly in the experimental group mice.The expression of COX2 in the hippocampal of the experimental group mice was significantly increased.Conclusion: Short-term damage to the nervous system and cognitive impairment may occur after the chest blast.Oxidative stress and blood-brain barrier injury were involved in cognitive impairment,and the oxidative stress and blood-brain barrier injury appeared earlier in the frontal cortex,while the hippocampal injury lasted longer.