| ObjectiveTo investigate cerebral aneurysms formation induced by hypertension in rats andthe relationship to early histologic changes of cerebral arteries.Material and method1．subjectadopt 75 male S-D rats, whose age were 6-7 weeks, body weight were 200-250 g,all the animals and labs are provided by animal experiment center of Shengjing hospitalaffiliated to China Medical University .2．experiment method(1) subgroup of animalsdivide 75 S-D rats into group A ,group B and group C randomly.Group A(experiment group):ligate the left common artery,electric coagulate thebialateral ramus posterior arteriae renalis from mesoabdominal approach of all the 30rats. ,one weeks after operation, start to give them 1% saline for drinking.Group B(hypertensive group):electric coagulate the bialateral ramus posteriorarteriae renalis from mesoabdominal approach of all the 30 rats. One weeks afteroperation, start to give them 1% saline for drinking.Group B(normal control group):no operation and give tap water for drinking.(2) measure the artery blood pressure of the rat tail1 day before operation,measure the artery blood pressure of the rat tail for theunderlying blood pressure, and measure blood pressure at 2 weeks after operation,6weeks after operation, 10 weeks after operation and before execute.(3) specimen adoption of the rat intracranial aneurysm 12 weeks later, all the rats were disclose thorax and intubated from left ventricleto the ascending arteriae aorta. firstly transcatheterly infused 30ml saline ,at the sametime, snip the vena cava to exsanguinations ,secondly, slowly inject 120ml 4%paraform 0．1M phosphate buffer (pH7．4) intravenously,cut of the neck after the rat isfilling fixation,open the intracrania cavity to obtain the brain,abstract carefully theWillis annulation, test it carefully under the 40 times microscope,especially theaneurysm like change of right anterior cerebral artery-olfactoryartery(ACA-OA).(4) the observation of aneurysm sample under light microscope10% formalin fixation,alcohol gradient dehydration,paraffin imbedding andconvention HE dyeing.(5) the examination of aneurysm sample under the transmission electronmicroscope force-fix the sample by soaking the aneurysm sample in the 2．5%glutaric dialdehyde for 24 hours.refix it by 1% osmium tetroxide, gradient dehydrationby acetonum, imbedding by Epon812, semithin section photics localization,ultrathinsection uranyl acetate and citric acid plumbum double staining, observate and takepicture the ultrathin section with JEM-1200EX type transmission electron microscope.3．statistics methodDo t-test of systolic pressure of different time between experiment group andcontrol group bySPSS for Windows 10．0 .When P<0．01,the discrepancy havesignificance.Result1．existence condition there are 28 survival rats in experiment group,29 ones inhypertension group,30 ones in normal control condition.there are 3 death rats isdysoemia,dying of malignant hypertension is not excluded.2．the blood pressure of experiment group and hypertension group is apparentincreasing from the second week,the blood pressure keep on increasing from thenon.the blood pressure of normal control group is in the normal range.the analysis ofvariance indicate : the blood pressure between A and B can't be considered to be different(P > 0．05) ;the blood pressure difference between the first two group A,B andthe third group C have significance(P < 0．01) .3．the observation result by light microscope and electromicroscope10 aneurysms are observed under the microscope in the 28 living rats of groupA,all the aneurysms are located in the crotch of ACA-OA.protophase stage aneurysms3 cases , progression stage of aneurysm 1 case,in the other 13 rats in group A and the 29rats in group B and 15 rats in group C,the aneyrysm-like stucture change are not beseen in the crotch and bole of the artery.Discussionthe rupture of intracranial aneurysm is usually in the appearance of simultaneoussubarachnoid hemorrhage and intracranial hemotoma,there is a high multilation rateand death rate .If we have correct cognition to the pathogenesy of this disease andadopt effective diagnosis,intervention and treatment,the prognosis will besignificantly improve.so it very significant to discuss the pathologicmorphous,succession and clinical treatment.because we can't study theformation,progression of aneurysm in human body,it is very important to found andinvestige effective brain aneurysm animal model,and so does the reveal of thepathogenesis.The rat aneyrysm model have the advantage of cheap,highly patency rate(becauseof fast arteriopalmus lead little possibility of thombosis formation), the vessel not easyto spasm,and is similar to the pathological change of human being.The incidence rate of rat aneurysm caused by renal hypertension is 10 % to 30%,in our experiment,the brain aneyrysm change incidence rate is 36% (10/28) ,it maybecause no infection,high survial rate and induce hypertension successfully. all theaneurysms are happened in the furcation of ACA-OA of the not excluded side ofcarotid artery,it may because the hemodynamic change and the degradation of vascularwall.in the base of hypertension,the one side obstuction of carotid artery increase thecerebral perfusion on the other side. Under the gigatic impact of blood stream,the core stream impact the furcation of ACA-OA and lead the endoelastic membranecorrupt,endothecium cell damage,the collogen of vascular elastic tissue and smoothmuscular layer and the vascular wall is damaged ,these reasons cause the aneurysmformation.In a word,the experimental model of rat hypertensen and aneurysm is cheap andefficienct,it have high aneurysm formation rate and is similar in the locus andpathological change to human beings,and also have expercially investigate value information of formation and progression of brain microaneurysm.ConclusionThe haemodynamic pressure increasing change and Willis annulationhyperperfusion is the paceing factor of intracranial aneurysm foundation, theendo-elasticic membrane and smooth muscle destroy is the main reason of brainaneurysm.
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