| Backgroud:As we all know,cerebrospinal fluid(CSF)plays many important roles in the central nervous system.Scholars agree on the function and secretion of the former,but there is still great controversy in the academic circle on its reabsorption path,which has lasted for many years.Although a large number of reports have described cerebrospinal fluid and its circulation in subarachnoid space,the understanding of the mechanism of cerebrospinal fluid reabsorption is still limited.Recently,more and more evidence shows that arachnoid granules and lymphatic capillaries are involved in the reabsorption of cerebrospinal fluid,and the role of the former seems to be more obvious.Exploring the mechanism and reabsorption pathway of arachnoid granules in cerebrospinal fluid circulation will help us better understand the significance of cerebrospinal fluid in health and disease,and may provide guidance for relevant clinical work to a certain extent.Arachnoid granulation(Ag)is a granular process formed when the arachnoid protrudes into the dural venous sinus,which is mainly distributed in the dura.As a"bridge" between subarachnoid cavity and vein,its main function is to absorb cerebrospinal fluid and remove particulate matter or macromolecules in cerebrospinal fluid.It plays an important role in cerebrospinal fluid circulation.In general,cerebrospinal fluid reabsorption is a phenomenon of hydrostatic pressure,which is closely related to the pressure difference between intracranial pressure and venous sinus.At present,the research on the function of arachnoid granules is still based on the structure.There is no more direct experiment to confirm the function of arachnoid granules,that is,it can not confirm or determine the role of arachnoid granules in transporting cerebrospinal fluid.The experimental animals selected in the experiment also have obvious limitations,which is difficult to simulate the pathophysiological process of human cerebrospinal fluid circulation.The deficiency of basic theory leads to the unknown etiology of cerebrospinal fluid circulation related diseases.The treatment can only focus on symptomatic treatment,and there is a lack of cause-tocause treatment.In the field of Neurosurgery,subarachnoid hemorrhage(SAH)is a very common cerebrovascular disease in clinic.In addition to directly causing damage to the central nervous system,it will also cause all kinds of serious complications in the whole body,with a high rate of death and disability.Although with the development and progress of medical technology and medicine,the clinical diagnosis and treatment of this disease have been improved to some extent,a considerable number of patients still have poor prognosis,which is mainly manifested in hydrocephalus secondary to subarachnoid hemorrhage.Although such patients can reduce the symptoms of increased intracranial pressure through shunt,there are still some patients who still have poor results after long-term treatment.It can be seen that subarachnoid hemorrhage seriously affects the quality of life of patients and threatens the life and health of patients.Therefore,exploring the pathogenesis of subarachnoid hemorrhage will help to provide patients with new treatment strategies and improve their clinical prognosis.Communicating hydrocephalus is one of the common complications after subarachnoid hemorrhage,and its incidence is about 20-30%.Due to the lack of thorough research on the cerebrospinal fluid circulation pathway and the unclear related complex pathophysiological processes,the treatment of this kind of hydrocephalus at home and abroad is mainly symptomatic ventriculoperitoneal shunt surgery.Previous studies on cerebrospinal fluid circulation pathway mainly came from animal experiments,which is difficult to truly reflect the human cerebrospinal fluid circulation process.In addition,the existing data mostly analyze the morphological characteristics of cerebrospinal fluid circulation from the perspective of anatomy,but there is still a lack of targeted functional research.Many scholars have used a variety of experimental animals to study the cerebrospinal fluid circulation pathway,and the great differences of species have also brought different experimental results,but the research on the cerebrospinal fluid circulation pathway of primates is very rare.Because arachnoid particles have great differences in different species and different development stages of species,I personally believe that the resorption pathways of cerebrospinal fluid are diverse,but there are primary and secondary.It is speculated that the extracranial lymphatic system of animals with developed sense of smell has a strong function of resorption of cerebrospinal fluid,and arachnoid particles are the main primates.According to the objective conditions,previous research and available data,we choose the cynomolgus monkey with more similar anatomical structure to human as the experimental obj ect,which is expected to draw a more accurate conclusion.For a long time,the industry has paid great attention to the related problems of subarachnoid hemorrhage,and the final pathway of arachnoid blood is closely related to the morphology and function of arachnoid granules.Therefore,studying the mechanism of the influence of arachnoid blood on arachnoid granules is also helpful to provide new strategies and ideas for the intervention and treatment of secondary hydrocephalus.For example,some studies have found that when subarachnoid hemorrhage,arachnoid granulosa cells are often blocked,and the incidence of hydrocephalus is very high;At the same time,some studies also suggest that after arachnoid blood,arachnoid villi will expand in different states,and some deposited red blood cells will be observed.These abnormal changes affect the reabsorption of cerebrospinal fluid by arachnoid particles.In addition,researchers found that in the animal arachnoid blood model,the endothelial cells of arachnoid granules increased,the microfibrils also increased,and the gap between cells became smaller.These structural and morphological changes may be related to the reabsorption disorder of cerebrospinal fluid.Domestic studies have found that in the rat spider blood model,the serum TNF of rats-α.The expression level of can significantly increase,which can induce the deposition of extracellular matrix,resulting in arachnoid granule fibrosis,subarachnoid cavity becoming smaller and basement membrane thickening,resulting in the accumulation of cerebrospinal fluid and the occurrence of hydrocephalus.Therefore,the study of cerebrospinal fluid circulation pathway,pathophysiological mechanism of arachnoid granules,mechanism of communicating hydrocephalus caused by subarachnoid hemorrhage,local anatomy of choroid plexus and other aspects is expected to provide further guidance for the prevention and treatment of hydrocephalus after arachnoid hemorrhage.Based on the above theoretical basis,the research of this paper mainly includes the following three parts:Part Ⅰ:The study on the morphological structure and intracranial distribution of arachnoid granules in cynomolgus monkeysObjective:To study the distribution and morphological characteristics of arachnoid granules in the brain of cynomolgus monkeys.Methods:Cynomolgus monkeys with similar anatomical structure to human were selected as experimental animals.A monkey was randomly selected as the blank control(All experimental animals are provided by regular laboratories,and have passed a number of inspection and testing standards,and are completely healthy individuals),and the number was M1.First,brain CT and MRI scanning were performed to record the relevant data.The specimens of superior sagittal sinus,transverse sinus,choroid plexus of lateral ventricle and choroid plexus of third and fourth ventricle were fixed with 4%paraformaldehyde in paraffin group and 2.5%glutaraldehyde fixed solution in electron microscope group.Paraffin embedded and pathological sections were performed to determine the location range of arachnoid particles,and the morphology of arachnoid particles was observed by high power transmission electron microscope.Results:CT results of cynomolgus monkey brain showed normal brain,no dilatation of ventricular system,no signs of hydrocephalus;MRI results showed the same as before,and some cynomolgus monkey brain showed suspicious arachnoid granule signal.Pathological sections of cynomolgus monkeys showed that arachnoid granules were distributed in the heart,kidney,superior sagittal sinus,choroid plexus,transverse sinus,lateral ventricle and sigmoid sinus.It mainly concentrated in the superior sagittal sinus and transverse sinus.Transmission electron microscopy results of cynomolgus monkeys:it was confirmed that the arachnoid granules were concentrated in the superior sagittal sinus and transverse sinus.The normal structure of arachnoid granules(superior sagittal sinus)and(transverse sinus)of cynomolgus monkeys were observed by transmission electron microscope.Conclusion:the arachnoid granules of cynomolgus monkeys are mainly distributed in the superior sagittal sinus and transverse sinus,and the distribution characteristics are scattered,clustered and irregular in shape.The distribution and structural characteristics of arachnoid granules in cynomolgus monkeys indicate that they are important devices for cerebrospinal fluid reflux and filtration.It is an important way for large and small molecular substances to pass through.Part Ⅱ:Changes of arachnoid granules in cynomolgus monkeys after SAHObjective:To establish models of subarachnoid hemorrhage and hydrocephalus and observe the changes of arachnoid granules.Methods:The study selected cynomolgus monkeys with similar anatomical structure to humans as experimental animals,and the blank control group was the same as above.The monkeys in the experimental group were sequentially numbered as M2,M3,M4,M5,M6,and M7 to establish an animal model of subarachnoid hemorrhage,which was then examined by CT and MRI.Specimens from the superior sagittal sinus,transverse sinus,lateral ventricle choroid plexus,third and fourth ventricle choroid plexus,etc.were taken,and the paraffin group was fixed with 4%paraformaldehyde,and the electron microscope group was fixed with 2.5%glutaraldehyde fixative for use;according to the first part of the experiment The location of the arachnoid granules determined in the arachnoid granules was obtained,and the arachnoid granules were observed by high-power transmission electron microscopy,and the morphological and structural changes of the arachnoid granules in the paraffin-embedded pathological sections were observed.Results:The subarachnoid hemorrhage model was successfully established by imaging examination and anatomy after repeated blood injection.With the increase of blood injection times,the sick monkeys showed decreased activity,poor food intake and delayed reaction.Results:CT and MRI showed that the ventricular system was dilated,which confirmed the successful establishment of hydrocephalus model.The arachnoid granules of hydrocephalus monkey were observed by high power transmission electron microscope,and extensive fibrosis of arachnoid granules was observed.After SAH,the choroid plexus was destroyed in different degrees.The pathological sections of transverse sinus,sigmoid sinus and superior sagittal sinus showed the changes of arachnoid granules.The pathological results of HE staining showed that the choroid plexus epithelial cells were destroyed and the structure was incomplete.Conclusion:In this study,the distribution of arachnoid granules in monkeys was determined,and the models of subarachnoid hemorrhage and hydrocephalus were successfully established.The results of the experimental group of animals showed that extensive arachnoid granular fibrosis,local related tissue dissociation,and structural damage(including choroid plexus)may be one of the important factors in the formation of hydrocephalus after subarachnoid hemorrhage.Part Ⅲ:The role and mechanism of AQP4 and AQP1 in cerebrospinal fluid of cynomolgus monkeys SAHObjective:Cerebral aquaporins(AQPs)are a group of proteins,mainly AQP4 and AQP1 in the brain,which are thought to play a key role in cerebrospinal fluid and interstitial fluid.The characterization of AQPs expression is important for understanding their role in CSF circulation.Therefore,establishing a subarachnoid hemorrhage model in cynomolgus monkeys and studying the expression changes of AQP4 and AQP1 in arachnoid granules in the hemorrhagic state can provide a theoretical basis for explaining the changes of hydrocephalus after subarachnoid hemorrhage.Methods:Cynomolgus monkeys were divided into control group and SAH group.The superior sagittal sinus,transverse sinus,choroid plexus and choroid plexus were taken.RT-PCR and Western blotting were used to detect the expression of AQP4 and aop1.Results:The expression of AQP4 and AQP1 increased in the superior sagittal sinus and transverse sinus of SAH cynomolgus monkeys.The expression of AQP1 in choroid layer of SAH cynomolgus monkeys decreased.Conclusion:The mRNA and protein expression levels of AQP4 and AQP1 in the superior sagittal and transverse sinuses of cynomolgus monkeys increased after spider blood;The expression levels of AQP1 mRNA and protein in choroid plexus decreased after spider blood in model animals.The results showed that the expression levels of AQP4 and AQP1 fluctuated in hydrocephalus lesions secondary to subarachnoid hemorrhage,suggesting that it may be a compensation and regulation mechanism for the reabsorption of cerebrospinal fluid. |
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