Experimental Study On Pathological Changes Of Brain In Rats With Skull Defect

ObjectiveInvestigate the effect of brain pathology on skull defect by establish a rat model of skull defect.Methods1.Use healthy SD rats to establish the model of skull defect.2.Animals were divided into four groups: sham group(animals exposed to bone but without opening the skull window);diameter 4 mm skull circular defect group;biparietal diameter 6mm central circular skull defect group;biparietal diameter 8mm central circular skull defect group.3.The behavioral changes of each group were detected by three factors:safety test,rotation test(RT)and nerve damage severity score(NSS).4.The expression levels of apoptosis-related proteins Bcl-2 and Bax in the cortex of brain tissue were detected by Western blot.5.The pathological changes of brain tissue were observed by immunofluorescence detect the expression of Caspase-3 and fluorescence TUNEL staining.Results1.On postoperative day 7.The unilateral parietal diameter 4mm circular skull defect group rats has new bone formation at the original skull window,there was approximately 50% of the original area was residually.The biparietal diameter 6mm central circular skull defect group rats has a very small amount of new bone formation at the edge of the skull window,and the most part of the skull window area was coverd fibrous tissue film.The skull window of biparietal diameter 8mm central circular skull defect group rats has no new bone formation,skull window was covered by fibrous tissue.On postoperative day 21,the skull window of the 6mm and 8mm skull defect group rats looked the same as the operative day 7.2.The grip of diameter 4 mm circular skull defect group rats has increased compared with the sham group on the 2nd day,4th day and the 6th day after operation;there was no statistical difference between groups.The grip of biparietal diameter 8mm central circular skull defect group rats has increased compared with the sham group on the 2nd day,4th day and the 6th day after operation;there was statistical difference between the 4th day postoperative group and sham group(P <0.05).To compared with the sham operation group;the grip of biparietal diameter 8mm central circular defect rats has reduced on postoperative day 2,but increased on the 4th day,6th day,14 th day and the 21 st day after operation;there was no statistical difference between groups.3.RT results showed that the running time of the biparietal diameter 8mm central circular defect group rats was shortened on the 2nd day,3rd day,4th day and the 5th day after operation compared with the sham group,there was no statistical difference between groups.4.NSS results showed that the NSS of the biparietal diameter 8mm central circular defect group rats had higher scores on the 2nd,4th day and the 6th day after operation,there was no statistical difference between groups.5.To compared with the sham group on postoperative day 7.The results of Western blotting showed that the expression of bcl-2 and Bax in the cortical brain tissue of the 6mm defect group rats' defect area was significantly lower,there was statistical difference between groups(P <0.05),Bax/bcl-2 ratio increased but no statistical difference between groups.The expression of bcl-2 in the cortical brain tissue of the 8mm defect group rats' defect area increased slightly,and decreased slightly in the non-defect area,there was no statistical difference between groups.The expression of Bax in the cortical brain tissue of the 8mm defect group rats' defect area was increased,and in non-defect area was increased significantly(P <0.05).6.To compared with the sham group on postoperative day 7.The immunofluorescence and TUNEL staining showed that there was no apoptosis expression in cortical brain and hippocampus of the biparietal diameter 6mm and 8mm central circular skull defect group rats.7.To compared with the sham group.Brain water content test showed that the brain water content of biparietal diameter 8mm central circular defect group rats has increased slightly on postoperative day 7,there was no significant difference between groups;decreased slightly on postoperative day 2 and day 3,there was no significant difference between groups.Conclusion1.The rats showed different degrees changes on pathology and praxiology after the skull defect with parietal diameter 4 mm central skull defect,biparietal diameter 6mm central circular skull defect and biparietal diameter 8mm circular central skull defect.2.Apoptosis of cortical neurons induced by skull defect was induced by mitochondrial pathway.3.Rats biparietal diameter 8mm central circular defect animal model can be used for experimental study on the evolution of intracranial pathology after skull defect.