Effect Of Splenectomy On Mitochondrial Autophagy In Rats With Traumatic Brain Injury

Objective: To explore the effect of splenectomy on mitochondrial autophagy in traumatic brain injury(TBI)in ratsMethods: One hundred healthy SD rats were sequentially divided into five groups using the random number method: Sham group(sham surgery group + sham splenectomy group,n=20),SPX group(sham surgery + splenectomy group,n=20),TBI group(craniocerebral injury group,n=20),TBI+SPX group((craniocerebral injury + splenectomy group,n=20),TBI+SPX +3MA group(The TBI group was modeled with reference to the Feeney method to establish an experimental model of TBI rats,and the sham-operated group only opened the skull window of the rats without striking;the splenectomy group fixed the rats supine on the operating table,routinely disinfected,spread the towels,and performed splenectomy.In the sham-operated group and the TBI group,the spleen was only gently lifted out of the abdominal cavity and incorporated back into the abdominal cavity;in the TBI+SPX+3MA group,2 μL of saline dissolved in 3MA(10 mg/kg)was injected intraperitoneally 1 hour before modeling,and in the rest of the groups,the same dose of saline was injected intraperitoneally 1 hour before modeling.The brain tissues of each group were extracted 24 h after modeling to detect the water content of brain tissue on the injured side,HE staining,Nissl staining,Tunel to detect apoptosis,transmission electron microscopy to observe the ultrastructure of brain tissue and Western blot detection.Blood was collected from the tail vein at 24 h,3 d,5 d and 7 d after modeling,and the serum was centrifuged for ELISA to detect inflammatory factors.The forelimb stepping test and m NSS score were performed before,24 h,3d,7d and 14 d after modeling for neurobehavioral testing,respectively.Results:(1)Compared with the control group,the behavioral scores of TBI rats increased at 24 h,3 d,7 d and 14 d after modeling,and the differences were statistically significant(P<0.05);at 3 d,7 d and 14 d after modeling,the behavioral scores of TBI+SPX group decreased compared with TBI group and TBI+SPX+3MA group,and the differences were statistically significant(p<0.05).(2)The water content of brain tissue on the injured side of the TBI rats increased significantly at 24 h after modeling compared with the control group(p < 0.05);the water content of brain on the injured side of the TBI+SPX group decreased compared with the TBI group and the TBI+SPX+3MA group(p < 0.05).(3)Compared with the control group,transmission electron microscopy of brain tissue at 24 h TBI showed obvious cellular edema,sparse matrix,sparse neurofibrillary filaments,swollen mitochondria,broken and reduced cristae,and the presence of autophagic lysosomes;the TBI+SPX group had reduced cellular edema compared with the TBI group and TBI+SPX+3MA group,and most of the mitochondria were still structurally sound,with parallel arrangement of cristae and more autophagic lysosomes.more.(4)Compared with the control group,the HE staining of the 24 h TBI group showed obvious pathological and inflammatory changes;the TBI+SPX group showed less pathological and inflammatory changes compared with the TBI and TBI+SPX+3MA groups.(5)Nissl staining of the modeled 24 h TBI groups compared with the control group showed neuronal loss and degeneration,sparse neuronal arrangement and blurred outline in each group;the TBI+SPX group significantly increased the number of neurons and improved the morphology of neurons compared with the TBI group and the TBI+SPX+3MA group.(6)The number of neuronal apoptosis was significantly increased in each group of modeling 24 h TBI compared with the control group(P < 0.05);the number of neuronal apoptosis was decreased in the TBI+SPX group compared with the TBI group and the TBI+SPX+3MA group,(P < 0.05).(7)Compared with the control group,the IL-6 level in the peripheral serum of each rat gradually increased over time after TBI,with the most significant increase in the third day,and the difference was statistically significant(p < 0.05));the IL-6 in the serum of the TBI+SPX group gradually decreased compared with the TBI group and the TBI+SPX+3MA group(p < 0.05).(8)PINK1 and Parkin protein expression increased in the 24 h TBI group compared with the control group(p < 0.05);PINK1 and Parkin protein expression increased more significantly in the TBI+SPX group compared with the TBI group and the TBI+SPX+3MS group(p < 0.05).(9)The differences were statistically significant.when comparing with the control group in modeling 24 h TBI group with increased LC3II/LC3 I protein expression,and TBI+SPX group with TBI and TBI+SPX+3MA group with increased LC3II/LC3 I protein expression(P< 0.05).Conclusion: Splenectomy may improve neurological function and attenuate secondary brain injury in TBI rats by regulating mitochondrial autophagy activated by the PINK1/Parkin signaling pathway,reducing brain edema,decreasing pro-inflammatory factor release,and inhibiting neuronal cell apoptosis.