Experimental Studies Of Cerebral Microcirculatory Changes After Subarachnoid Hemorrhage In Rabbits

Part one:Morphological changes of cerebral arteries in rabbits double-hemorrhage model evaluated by DSA and corrosion casts Objective: To investigate the serial morphological changes of intraparenchymal arterioles after SAH in rabbits.Methods: SAH was produced by injecting autologous no-heparinized arterial blood 1ml/kg body weight into subarachnoid twice at 48-hour intervals in 12 rabbits.6 rabbits underwent DSA 3,7,or 14 days after SAH to measure BA diameter and calculate CVS ratio,then perfusion-fixed.Sectioned slices were examined by light microscopy.6 rabbits were killed 3,7,or 14 days after SAH,microvascular corrosion casts produced by arterial injection of polyester resin were examined using SEM,arterioles of each animal were measured. In control animals (n=4) and in healthy control animals(n=4),the same examination and evaluation were performed. Results: No neural deficit were observed in SAH 3d animal,and in a animal CVS was 16.9% by DSA.In SAH 7d,one rabbit was observed neural deficit but no BA narrowing,CVS 20.9% was obtained in the other rabbit with no neural deficit.Corrosion casts of arterioles showed tapered narrowing with folding after SAH,and the width of the arterioles significantly decreased at 3 and 7 days after SAH. Annular imprint was detected at the beginning of capillary vessels.Morphological examination by light microscopy showed a significant decrease of internal diameter of arterioles associated with a increase of wall thickness.These findings improved 14 days after SAH. Control animals receiving subarachnoid injections of nature saline showed no significant differences compared with healthy control animals.Conclusions: BA narrowing does not accord with the neural deficit after SAH. Corrosion casts-SEM can observe the surface structure changes of arterioles, and three-dimensional structure.These results suggest that the changes of intraparenchymal arterioles follow SAH. Part two: The experimental study of hemodynamics changes after subarachnoid hemorrhage in rabbits Objective: To investigate the hemodynamics changes after SAH in rabbits with PCT and LDF,and the value of PCT in clinic. Methods: PCT was used at 1,3,7 and 14 days in rabbits that received two subarachnoid injections of autologous arterial blood (1ml/kg body weight)to induce SAH. rCBF,rCBV, TTP were measured based on the S-T curve.LDF was used at the same time for rCBF. Results: rCBF detected with PCT clearly decreased as early as 3 day after SAH increased at 7 day but at 14 day it was abnormal.rCBV decreased markedly at 3 day and increased at 7day,then came back. TTP was prolonged from 1d,marked at 3d,decreased at 7d and was abnormal at 14d.rCBF detected by LDF was similar to that of PCT,and the relationship is about 0.9563. Conclusions: PCT is a convenient and effective technique to evaluate hemodynamics after SAH. Analyzing the relationship of rCBF,rCBV,and TTP is helpful to know the status of the capillary vessels in brain and can provide functional information. LDF is a exact,traumatic method,the parameter detected is less than PCT. Part three:The experimental study of metabolic changes after subarachnoid hemorrhage in rabbits Objective: To evaluate the metabolic changes after SAH in rabbits.Methods: SAH was produced in rabbits by a two-hemorrhage method,and the rabbits wereexamined by MRS at 3,7 and 14 days after SAH. Results: NAA/Cr+Cho ratio was markedly decreased at 7d after SAH.It lightly rose again at 14 day. Conclusions: MRS can detect the change of NAA,Cr,Cho after SAH,and to estimate the neuron livability.The decrease of NAA was later then rCBF suggested that the metabolic change was the result of cerebral vascular spasm. Part four: Effect of cyclosporine-A on microcirculation after subarachnoid hemorrhage in rabbits Objective: To evaluate the effect of cyclosporine-A on microcirculation and to explore the mechanism of microvessel changes after subarachnoid hemorrhage in rabbits.Methods: SAH was produced by a two-hemorrhage method.CSA 5mg/kg was injected after SAH,once a day for five times.ICAM-1 was detected by IHC,PCT for rCBF,MRS for NAA,microvascular corrosion casts for morphological changes of microvessels.Results: The animal behavior improved slightly after CSA injection.ICAM-1 staining intensity deceased.Morphological changes of microvessels improved,and rCBF,NAA increased.Conclusions: CSA can improve the microcirculation partly.Inflammation takes part in the change of microvessels after SAH.