Optimization Of Subarachnoid Hemorrhage Rat Model And Correlative Study On Pathogenesis Of Early Brain Injury

Background:Subarachnoid hemorrhage(abbreviated as SAH)refers to a clinical syndrome caused by the rupture of diseased blood vessels at the bottom of the brain or on the surface of the brain,resulting in direct blood flow into the subarachnoid space,accounting for 5%of all strokes·～10%.Studies have shown that approximately 1/4 of all patients with primary subarachnoid hemorrhage have died,whereas half of the surviving patients have residual neurological deficits.As a clinically very serious and common disease,SAH has a very heavy economic burden on society and families because of its high mortality and morbidity.Therefore,SAH treatment intervention has always been the focus of neurosurgery research.Early brain injury(EBI)and delayed brain injury(DCI)are two major complications that occur in SAH patients.In the past few decades,cerebral vasospasm(cvs)occurred from the 4th to the 10th day after SAH was considered to be an important cause of adverse outcomes.The latter study used interventions to relieve cerebral vasospasm after SAH,but SAH The prognosis was not significantly improved.It can be seen that the main reason for the poor prognosis of SAH is not CVS.The concept of early brain injury(EBI)was proposed.EBI refers to a series of complex and variable pathophysiological changes that occurred within 72 hours after SAH.The main factors included elevated intracranial pressure(ICP),disruption of the blood-brain barrier(BBB),changes in cerebral perfusion pressure,oxidative stress,inflammatory response,imbalance of ion homeostasis,autophagy,and apoptosis.After continuous experimental research,people began to believe that EBI may be the main reason for the poor prognosis after SAH.The characteristics of EBI are earlier,multiple pathways,and complicated prognosis.At present,the related pathophysiological mechanisms have not been fully studied.The interaction between them remains in a variety of scenarios and has not been completely unified.The system’s conclusion,which also adds difficulty to the treatment of EBI.The current research on EBI focuses on experimental intervention-related experiments,and studies tend to focus on a single pathophysiological change,there is no comprehensive study comparing the trend of changes in the mechanisms,and the potential between them The links,while the path of EBI development is diverse,the related pathophysiological changes are not separate processes,but interact and promote each other.Therefore,detect and understand the trends of related pathophysiological changes,and synthesize the possible changes through trend changes.The influence relationship is particularly important.Objective:Based on the optimized SAH rat model,through the study of EBI-related important pathophysiological changes,to find out their trends in the EBI and the possible links between each other,to further clarify the mechanism of action of EBI,but also for the incidence of Mechanisms to study multiple targets provide the basis and possibility.Methods:168 rats were randomly divided into blank control group,sham operation group(Sham),SAH group,36 control groups,36 sham operation groups,and 96 SAH groups.According to the study time,the SAH components were determined.The three subgroups are the 24 h,48 h,and 72 h groups.The SAH model was established using a modified pre-fusion chiasmata injection method.The brain specimens were visually observed and the animal mortality was calculated and compared with the traditional model-building method.Based on the optimization of the model,according to the research needs,the data were collected and collected at the corresponding time points after SAH,and the important pathological and physiological changes related to EBI were monitored,including neurological function score,brain edema level,blood-brain barrier destruction degree,and oxidation.Excitatory levels,CGRP(calcitonin gene-related peptide)changes,apoptosis,and autophagy expression levels.One-way analysis of variance(ANOVA)or Kruskal-Wallis rank sum test was used for statistical analysis.The data between different groups were compared to understand the characteristics of the changes in the pathophysiological changes within 72 hours after SAH,and they were combined with each other.Analyze the role of related changes in the EBI process and further clarify the mechanism of action of EBI.Result:1.The mortality rate of SAH model established by the optimized presyrinctia pool injection method is lower than the ordinary method,and the model is more stable.2.In the blank control group and the sham test group,the rats had no neurological dysfunction or showed no obvious manifestations.After the occurrence of SAH,the EBI-related neurological dysfunction was obvious,and reached a high level at 24 h after SAH,and thereafter at 48 h and 72 h.Gradually decreased,but 72h is still higher than the control group.3.Compared with the blank control group and the sham test group,brain edema and oxidative stress response were significantly enhanced in EBI,and reached a higher level 24 h after SAH,and gradually increased at 48 h and 72 h.4.There was no significant blood-brain barrier disruption in normal rats,but it was evident in the EBI after SAH.It reached a level 24 h after SAH and decreased slightly at 48 h and 72 h,but it was still significantly higher than the control group at 72 h.5.There was a small amount of CGRP in cerebrospinal fluid of rats.The concentration of CGRP in cerebrospinal fluid increased significantly within 24 hours after SAH,which was more than 10 times of the normal value.It decreased significantly at 48 hours and 72 hours,but it was still several times higher than normal at 72 hours.6.Autophagy and apoptosis were slightly expressed in the brain tissue of normal rats,and the levels were lower.However,both of them increased significantly in EBI after SAH and reached a higher level in 24 hours.Autophagy decreased at 48h and 72h but remained above normal levels.Conclusion:1.The mortality rate of the SAH rat model established by the presyrinx pool blood injection method is reduced after optimization,the model variation is small and stable,the operation is convenient and time-saving,and it is easy to popularize.2.The vasogenic brain edema is not dominant in the later period of EBI,and the continuous enhancement of brain edema in late EBI may be related to the cytotoxic brain edema caused by cerebral hypoxia and energy-dependent Na+-K+ ion pump activity reduction.3.There is a close relationship between apoptosis and blood-brain barrier disruption in EBI process,which may be the key factor causing BBB damage.However,the BBB damage caused by oxidative stress in late EBI may be limited.CGRP increased sharply at 24 h after SAH,and was significantly higher than normal at 72 h.At this time,CVS occurred rarely.With the decrease of CGRP,CVS began to appear,and the decreasing trend was in line with the time point of CVS,suggesting that CGRP The decrease is likely to be an important reason for the occurrence of CVS.