| Objective: To establish the model of severe traumatic brain injury(STBI)in rats,the effects of diammonium glycyrrhizinate(DG)on nerve regeneration repair in rats with severetraumatic brain injury were observed from the perspective of Wnt/β-catenin signaling pathway.Methods:72 healthy male SD rats(SPF grade)were divided into 4 groups according to the random number table,STBI model group,ganglioside treatment group and DG treatment group,18 rats in each group.Acording to 1,3 and 7 days after modeling,the rats were divided into three subgroups,six rats at each time point.Except the normal control group,The animal model of other groups was reproduced by referring to Feeney’s free fall impact modeling.6h after film preparation,monosialotetrahexosylganglioside sodium injection and DG injection were injected via tail vein of ganglioside group and diammonium glycyrrhizinate group respectively;normal control group and STBI model group were given the same amount of nor-mal saline,once a day.On the1 st,3rd and 7th day,6 rats in each group were taken on the 1st,3rd and 7th day after the preparation of the membrane for neurological severity scores(NSS),and t-hen the blood of the abdominal-a orta and brain tissues were taken.Enzyme-linked immunosorbent assay(EL ISA)was used to detect levels of brain-derived neurotrophic factor(BDN F)and nerve growth factor(NGF)in serum;pathological changes of subgranular zone(SGZ)were observed under light microscope after hematoxylin eosin(HE)staining;real-time quantitative polymerase chain reaction(RTq PCR)was used to detect the ex-pression of Wnt3 a,β-catenin,GSK-3β a-n d Ax-in mRNA.Results:(1)There was no neurological deficit in the normal control group,and the neurological deficit score was 0.The neurological deficit score of the rats in the severe brain injury model group increased significantly on the 1st day after modeling(p<0.01),and then decreased gradually with time.The 3rd day after the treatment with ganglioside,the neurological deficit score of the rats was significantly lower than that of the severe brain injury model group(p<0.01,p<0.05).The 1st day after the treatment with DG,the neurological deficit score of the rats was significantly lower than that of the severe brain injury model group(p<0.01),it showed a gradual downward trend with the extension of time,the difference was still statistically significant on the 7th day(p <0.01).and the neurological deficit score of DG treatment group was significantly lower than that of ganglioside treatment group from the 3rd day(p<0.01).(2)under the light microscope,no obvious pathological changes were observed in the hippocampus SGZ of the normal control group,The cell layer and structure were clear,the arrangement was relatively close and orderly,and no degeneration and necrosis of nerve cells in normal control group.Neurons and tissues were damaged and destroyed at different time points in the STBI model group.After ganglioside or DG treatment,the damage of nerve tissue in rats was improved,gradually improved with time,and the effect of DG was more obvious.(3)In the normal control group,the mRNA expressions of Wnt3 a andβ-catenin were almost not expressed.On the 1st day after STBI,the mRNA expressions of Wnt3 a and β-catenin in the hippocampus of rats were significantly increased(p < 0.01),and then gradually increased with time.The mRNA expressions of Wnt3 a and β-catenin in the hippocampus was significantly higher than that in STBI model group on the 1st day after ganglioside or DG treatment added,the effect of DG is more significant than that of ganglioside(p<0.01).It was gradually increasing with the extension of time and the difference was still statistically significant up to the 7th day(p<0.01).(4)The mRNA expression of GSK-3β and Axin was higher in the hippocampus of the normal control group,and there was no obvious difference between the three time points on the 1st,3th and 7th day.On the 1st day after STBI,the mRNA expression of GSK-3β and Axin in the hippocampus of the STBI model control group rats decreased significantly(p < 0.01),and then gradually increased with time.The mRNA expression of GSK-3β and Axin in the hippocampus of the rats treated with ganglioside or DG on the first day was significantly lower than that of the rats with severe brain injury(p<0.01),and the effect of DG was more significant than that of the rats treated with Ganglioside(p<0.01,p<0.05).At the same time,with the extension of time,it showed a gradual downward trend and still had statistical significance up to the7 th day.(5)There was little BDNF and NGF in the serum of normal control group rats.Compared with the normal control group,the content of BDNF and NGF increased significantly in the serum of the rats in STBI group on the 1st day after STBI(p < 0.01).The content of BDNF and NGF in the serum was significantly higher than that in the severe brain injury model group(p<0.01,p<0.05)on the first day after adding ganglioside or DG,gradually increased with time,and still had statistical significance on the 7th day(p<0.01).The effect of DG was more significant than that of ganglioside(p<0.01,p<0.05).Conclusion:DG can promote the recovery of nerve function in rats with severe TBI.Its mechanism may be related to the regeneration of nerve cells proliferation and differentiation by Wnt/β-catenin signaling pathway and the reconstruction of nerve tissue in SGZ of hippocampus. |
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