Comparative Research In The Evaluation Of Therapeutic Effect Of Edaravone-treatment For Ischemia-reperfusion Brain Injury By MR And Pathological Changes.

Objective: Cerebral arterial thrombosis is not a rare internal medical disease in clinic. living standard. With the enhancement of people's living standard, there is an increase in Cerebral arterial thrombosis cases. Early diagnosis is the precondition of early therapy for cerebral infarction. The main goal of clinical therapy for cerebral infarction is to protect the ischemic penumbra(IP) and prevent it from developing irreversible cerebral infarction. The thrombolytic therapy has gained a general acceptance in early therapy for cerebral infarction,so it is the key to rescuing the IP successfully.And it is the core that effective measures should be taken in order to reduce the reperfusion injury when the thrombolytic therapy is performed. Edaravone is a potent scavenger of hydroxyl radicals. Recent results indicate that edaravone has an inhibitory effect on lipid peroxidation by scavenging free radicals , prevents vascular endothelial cell injury, prevents cortical edema, reduces the infarct volume,and improves neurological deficits. (With the raising of human being's health consciousness,there appears an increase of Cerebral arterial thrombosis cases that the thrombolytic therapy was performed.)MR disfusion weight imaging (DWI) and perfusion weighted imaging (PWI) sequence provides a new method of the early diagnosis of cerebral arterial thrombosis and the identification of IP and its maintaining time and volume can be sensitively demonstrated,which can provide individual information of the thrombolytic therapy and effect of neuroprotective agents . So far there has been no report that evaluated the curative effect of edaravone for ischemical- reperfusion injury of the transient cerebral ischemia by DWI and PWI .The purpose of our research is to establish ischemical reperfusion model of middle cerebral artery occlusion model (MCAO) in rabbits, and to exploit the identification of IP,its maintaining time and volume by DWI and PWI sequence studies within 72hours.A comparison of the MRI and the pathomorphological results of microscopy and immunohistochemical method were made in order to provide a theoretical foundation for the guidance of the clinical therapy and to evaluate the prognosis and curative effect of edaravone.Method: 48 New Zealand white rabbits were chosen (provided by Hebei Medical University Zoological Center), no gender restriction, weight 2.5 to 3 kg, 4 to 6 months old. Those rabbits were randomly divided into three groups : edaravone , ischemic reperfusion (I/R) and sham. Sham group(n=8) was sham-operated.In edaravone group(n=20) and I/R group (n=20),the focal cerebral ischemic reperfusion model was made. In edaravone group, edaravone injection was administrated intravenously after reperfusion,while normal sodium injection was used in I/R group. The rabbits were kept in the center for one week before doing the experiments. The rabbits were not allowed eating but drinking for 12 hours when the experiments started. The three groups of rabbits were all intravenously anaesthetized slowly with via auris vein, slowly with the rabbits lying on the stage, were fixed and kept breathing freely with their rair on the neck removed later. Then they were sterilized an covered with the operation part being exposed. Under the sterilized conditions, the neck was cut along the center line, the subcutaneous tissue and muscle were separated, the common carotid artery and internal carotid artery were exposed. In edaravone and I/R group, the focal cerebral ischemic reperfusion model was made by inserting a wire (d=0.53mm) into middle cerebral artery (MCA) through common carotid artery and internal carotid artery directly and pulling it out 30min later.Immediately after the occlusion, the animals were transferred to the MRI scanner and diffusion weighted images were acquired. If there was high signal intensity on DWI and low signal intensity on apparent diffusion coeficient (ADC) map,then the focal cerebral ischemic reperfusion model was successful. MRI was performed 15 minutes before reperfusion and 0.5, 2,4,6,12,24,48 and 72 hours after withdrawal of the suture. To monitor infarct evolution, diffusion- and T2-weighted images were acquired at each imaging time point (see the above). In addition, PWI was performed at 2 hours after withdrawal of the suture to determine adequate reperfusion. Infarct volume, neurological deficit score, ADCR , the releasing of CytC and activation of bcl-2 were assessed by MRI, optical microscope and immunohistochemical method. The application was evalued in the curative effect of thrombolytic therapy in Hyperacute Cerebral Infarction by DWI and PWI .Results:(1) 48 New Zealand white rabbits were taken in this study, but seven rabbits failed in making focal cerebral ischemic reperfusion model or died after reperfusion; 41 rabbits entered the final analysis .(2) Sham group had no neurological deficit, in edaravone group neurological deficit score was significantly lower(1.31±0.56) than that in I/R group(2.28±0.47) after 24h after reperfusion(.P<0.05) (3) In edaravone group and I/R group, DWI abnormalities reversed transiently during the early reperfusion period but recurred after 4-12 hours. (4)Compared with I/R group, there was no significant difference of the ADC ratio in the core of infarction in edaravone group. (P > 0.05). (5) Compared with I/R group, there was significant difference of the ADC ratio in the perimeter of infarction in edaravone group (P< 0.01), Furthermore, the evolution tendency after reperfusion were significant difference in each time point(P< 0.01).(6) Compared with I/R group, there was significant difference of the T2WI signal intensity ratio in the focus of infarction in edaravone group (P< 0.01), Furthermore, the evolution tendency after reperfusion were significant diference in each time point(P< 0.01). (7)When edaravone was administrated after reperfusion, MRI-derived infarct volume was significantly lower than that in I/R group [(230±78)mm3 vs (425±114)mm3, P<0.05]. (8)In I/R group,cerebral necrosis and edema were more sprious than edaravone group in the same time point under examination of optical microscope. The ischemic penumbra showed stronger expression of bcl-2 and lower release of cytochrome C presenting in edaravone group than in I/R group(P<0.01).Conclusion:1. Reperfusion after 30 minutes of ischemia appears to be mainly complicated by secondary ischemic damage as is shown by the delayed recurrence of the DWI lesions.2.Artificial colour map of DWI may help to detect the position and its maintaining time and volume of the IP.3. The RADC value of IP and the infarction core are different, so IP can be found by RADC value.4. The identification of IP and its maintaining time and volume can be sensitively demonstrated by DWI and PWI.5. Edaravone-treatment can inhibit the release of cytochrome C from mitochondria to cytosol and provided an increase in Bcl-2 expression within the peri-infarct area. Edaravone shows an excellent neuroprotective effect against ischemia-reperfusion brain injury.6. Edaravone shows an excellent neuroprotective effect against ischemia/reperfusion brain injury by inhibiting the cytotoxic edema and reducing vasogenic edema within the IP.7. DWI and T2WI can give the evaluation of therapeutic effect of edaravone, which may shows an excellent neuroprotective effect against ischemia-reperfusion brain injury. MRI can provide useful information for the thombolytic therapy and monitor the therapeutic effect of neuronprotectants.