Neuroprotection Of Tauroursodeoxycholic Acid On Subarachnoid Haemorrhage And Involving Mechanisms

Background: subarachnoid hemorrhage(SAH)is a serious cerebrovascular disease,which is not only related to the high mortality of first hemorrhage and rebleeding,but also a large number of patients will develop delayed neurological deficit even after successful clipping or curly fixation of aneurysms.Previous studies have focused on cerebral vasospasm(CVS),which is considered to be the main cause of delayed neurological deficit.However,antiangiotensin drugs can not improve the prognosis in clinical trials,making people realize that early brain injury(EBI)plays an important role in the pathological process of subarachnoid hemorrhage.Immediate events associated with subarachnoid hemorrhage,including reduced cerebral blood flow and global cerebral ischemia,can trigger a series of pathological changes prior to the onset of delayed vasospasm.Pathological changes in the early stage of bleeding can lead to the destruction of the blood-brain barrier and cell death.It is not enough to treat subarachnoid hemorrhage only by paying attention to the treatment of vasospasm and not considering the early brain injury at all.On the contrary,the purpose of treatment intervention must be to prevent the molecular cascade reaction of early brain injury,which may lead to poor long-term prognosis other than vasospasm.Early brain injury plays an important role in the pathological process of subarachnoid hemorrhage,and endoplasmic reticulum stress(ERS)is an important pathophysiological cause of early brain injury.Taursodeoxycholic acid(TUDCA)is a hydrophilic bile acid,an endoplasmic reticulum stress inhibitor and chemical chaperone,which can inhibit apoptosis and reduce inflammation.In recent years,it has been pointed out that TUDCA plays an important role in inhibiting endoplasmic reticulum stress and preventing early brain injury in several central nervous system diseases,such as craniocerebral trauma(traumatic brain injury),cerebral hemorrhage(intracerebral hemeorrhage)and neurodegenerative disease(neurodegenerative diseases).Objective: The purpose of this study was to observe and analyze the mechanism of early brain injury induced by endoplasmic reticulum stress in mice and the protective effect of TUDCA on SAH in order to provide theoretical reference for TUDCA in the treatment of SAH.Methods:(1)experiment 1: the subarachnoid hemorrhage(SAH)model of C57BL/6 mice was established by carotid artery puncture.One day later,the brain tissue was separated,the gross morphology of SAH model specimen was observed,and the subarachnoid hemorrhage was observed by HE staining to confirm the success of the model.(2)experiment 2: C57BL/6 mice were randomly divided into 7 groups: SAH 3h,SAH 6h,SAH 12 h,SAH 1Day,SAH 3Day,SAH 5Day and SAH 7Day.The cerebral blood flow(CBF)was measured by laser speckle,then the protein was extracted from brain tissue,and the expression of GRP78(ER stress marker)was detected by Westernblotting.(3)experiment 3: C57BL/6 mice were randomly divided into three groups: sham operation group(sham group),control group(SAH+Veh group)and TUDCA group(SAH+TUDCA group).Six mice in each group,24 hours after the establishment of the model,the neurological function of the experimental mice was scored,the changes of cerebral blood flow after vasospasm were detected by laser speckle,and the SAH grade of the mice was evaluated.At the same time,the expression of GRP78?,p-PERK,PERK,p-eIF2?,eIF2?,ATF4 and other related proteins was detected by Western blot.(4)experiment 4: C57BL/6 mice were randomly divided into three groups: sham operation group(sham group),control group(SAH+Veh group)and TUDCA group(SAH+TUDCA group).There were 6 mice in each group.24 hours after the establishment of the model,the water content of brain tissue was measured by dry and wet weight method.(5)experiment 5: C57BL/6 mice were randomly divided into three groups: sham operation group(sham group),control group(SAH+Veh group)and TUDCA group(SAH+TUDCA group).There were 6 mice in each group.24 hours after the establishment of the model,EB leakage test was used to detect the destruction of blood-brain barrier.Results: the expression of ERS marker GRP78 was the highest in mice with SAH for 24 hours.laser speckle showed continuous low blood flow in CBF in mice with SAH within 24 hours.After 24 hours of modeling,there was no significant difference in SAH score between the treatment group and the control group,but the neurological function score in the administration group was higher than that in the control group.The results of dry and wet weight method showed that the brain edema of the mice in the TUDCA group was lighter;western blot results showed that the ERS reaction and the decrease of cerebral blood flow in the administration group were inhibited,and the level of apoptosis was also significantly inhibited.Conclusion: for the mouse model of subarachnoid hemorrhage,TUDCA can improve nerve function in the early stage of SAH,reduce ERS reaction in order to increase the recovery of cerebral blood flow,inhibit apoptosis and provide neuroprotective effect.PERK?eIF2??ATF4 may be the related mechanism.