| PART1Preliminary research about characteristics of acute brain injury afterintraventricular hemorrhageBackground and objectiveIntracerebral hemorrhage (ICH) is one of the most common diseases threateninghealth of the aged，which is the least treatable form of stroke associated with high morbidityand mortality. No effective intervention strategies and treatment method has been found totreat the neurological deficit caused by ICH. Extension of the hemorrhage into theventricles following ICH results in intraventricular hemorrhage (IVH), which occur upto30%～50%in patients with ICH. In the past few years, a number of clinical trials haveconfirmed that IVH is an independent predictor of poor outcome in spontaneous ICH. Moststudies of IVH focused on the pathophysiology mechanisms and therapeutic strategies ofsecondary hydrocephalus, while little attention has been paied to the characteristics andmechanisms of acute brain injury after IVH. Early fibrinolytic therapy and externaldrainage could effectively resolve intraventricular clot and hydrocephalus formation inrecent clinical trials but failed to low the mortality or improve favorable outcome.According to this, we proposed that，except for hydrocephalus，acute brain injury after IVHmay be a key factor for poor prognosis in IVH patients. To this, we established the IVHmodel by autologous blood injection to right intraventricular and researched thecharacteristics of acute brain injury after IVH.Material and MethodsMale Sprague Dawley (SD) rat were supplied by experimental animal center ofDaping hospital, Third Military Medical University. SD rats (n=44) were randomly dividedinto two groups: saline and IVH group. Male Sprague-Dawley rats received an infusion ofeither200ul autologous whole blood or saline. The rats were decapitaled24hours (hr) or48 hr later. At24hr: the reliability of rat IVH models were detected by Micro-CT and grossspecimen section, we measured brain water content by dry-wet weight method andobserved blood-brain barrier damage using evans blue staining and IgG expression ofchoroid plexus at48hr. The accumulation of iron was observed by extraction of the lateralventricular walls7days after IVH.Results1.Micro-CT and gross brain specimens present intraventricular hemorrhage casting,lateral ventricular dilation; which suggests the reproducibility and reliability of this IVH ratmodel.2.24hr after blood infusion, the brain water content of bilateral hemispheres increasedobviously in IVH rats comparing with saline rats.3.24hr after blood infusion, blood-brain barrier damage exists in IVH group (Evansblue exudation lot of brain tissue), and the BBB remains open until48hours (IgGexpression increased).4. Hemosiderin deposition on intraventricular wall can be seen at7days by rightventricle extraction, which suggesting iron overload at IVH group rats.ConclusionsVentricular expansion, cerebral edema, blood-brain barrier damage were the basicpathological features of acute brain injury and iron overload at7d after IVH, which may bekey factors leading to poor prognosis of IVH. PART2The damaging effect of iron and neuroprotective effects of edaravoneafter intraventricular iron infusion in ratsBackground and objectiveRecent studies have confirmed that iron overload after ICH play a key role in thedisease process. Our previous studies have proved iron overload after IVH is closely relatedto the occurrence of hydrocephalus as well. The first part of the study showed thatventricular dilation, brain edema, blood-brain barrier damage and iron accumulation occurafter acute brain injury, whether iron overload play a key role in IVH after acute brain injury is not clear. Studies have shown that oxidative stress is another important damagingmechanism after ICH but whether oxidative stress taking a part in the brain damage inducedby iron overload after IVH has not been proved yet. Edaravone is a free radical scavenger,has been shown to alleviate tissue damage caused by oxidative stress. So we established arat model by lateral ventricle iron infusion. After surgery, brain injury was observed toelucidate whether edaravone play a protective role in neurological function by reduceoxidative stress.Material and MethodsThis research is composed of two parts. Part I,99Male SD rats were randomly divided intosaline, FeCl2and FeCl2-Ed group (n=33). At24hr: we measured brain water content by dry-wetweight method, observed blood-brain barrier damage using evans blue staining, the MDA contentand SOD activity were determined with chemical method, hippocampus damaged byFLUORO-JADE C immunofluorescence staining and TUNEL immunohistochemistry. Ciliaultrastructural pathology were observed by SEM, and brain water content, blood-brain barrierdamage, MDA content and SOD activity were detected when give free-radical scavengeredaravone therapy. Part II,15male SD rats were randomly divided into saline, FeCl3and FeCl3-Edgroup(n=5). Learning and memory impairment after iron infusion to ventricle were observed byplace navigation(22-27days) and spatial probe (28day); Hemosiderin deposition onintraventricular wall were observed by stripping the right ventricle. Ventricular ciliaultrapathological changes were detected using scanning electron microscopy after Morris watermaze. We also observed whether or not radical scavenger edaravone improve long-term learningand saptial memory, can it alleviate ventricle wall injury and cilia damage in rats at28days.Results1. Ferric chloride intraventricular injection can caused changes as follows: bothhemispheres of brain tissue water content increases, blood-brain barrier damage,oxidative stress markers malondialdehyde levels increased, superoxide dismutase activitydecline, a large number of nerve cells in the hippocampus degeneration, apoptosis,intraventricular wall edema, tissue exfoliation and cilia damage. Free radical scavengeredaravone can alleviate iron dichloride intraventricular injection resulted in bilateralhemispheres of brain water content increases, reducing the content of oxidation products,improve the vitality of superoxide dismutase, reduction of hippocampal neuronal injury, and play a protective role on the intraventricular wall tissue and cilia damage.2. Morris water maze place navigation test (22-27days) in each group rats show thatlatencies progressively shorter comparing with the training times, the best scores is salinegroup, followed by FeCl3-Ed group, and finally FeCl3group. Spatial probe test (28days)Showing rats group of FeCl3intraventricular injection spent shortest times, swimmingdistances and cross platform times reduce in the target quadrant, which all can be betterwhen use edaravone therapy.3. At28days, hemosiderin deposition is still visible in ferric chloride group, scanningelectron microscopy showed partial loss of cilia, the surface coating of high electron-densematerial (hemosiderin); edaravone, free radical scavengers can reducing the accumulationof iron and cilia loss in the intraventricular wall.Conclusions1. Intraventricular injection of iron can lead to brain edema, blood-brain barrierdamage, elevated levels of oxidative stress products, hippocampal neuronal damage,ependymal cells of intraventricular wall damage and cilia loss, learning and memorydisorders; these pathological features have some similarities with acute brain injury afterIVH.2. Edaravone, free radical scavenger can alleviate the acute brain injury caused byintracerebroventricular injection of iron ions, such as brain edema, blood-brain barrierdamage, increased oxidation product content, meanwhile it can improve long-term learningand memory and reduce cilia loss caused by iron, which suggest it’s neuroprotective effectsof reducing iron oxidative stress, providing experimental and theoretical support for actuebrain injury of clinical patients after IVH. |
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