Evaluation Of Cerebral Ischemia Model In Rats And Correlation Between The GFAP, SYN And Nogo-A Expression And Neurological Outcome During The Recovery After MCAO In Rats

Part I Compared both neurological function and infarct size at different cerebral ischemia timeObjective:To investigate the location of infarct and the stability of neurological deficit after middle cerebral artery occlusion (MCAO) made by Longa method and the influence of neurological function and infarct size at different times reperfusion the MCAO model, so to making clear the reliability and the best time of reperfusion MCAO model, to provide a basis for further experiments.Methods:22 SD-rats were randomly divided into 1h (n= 6),2h (n= 6),4h (n= 6) and 6h (n= 4) groups, made the MCAO model by Longa method, the rats will reperfusion at 1h,2h,4h,6h after occlusion respectively. Functional tests and TTC staining were performed.Results:After MCAO rats have significantly neurological deficit, 1d after MCAO, the mNSS score of 1h,2h,4h and 6h groups were 6.33±0.82,9.83±1.17, 10.83±1.17,12.00±0.81, respectively. All groups have statistical significance (P<0.05), except the 2h and 4h groups,4h and 6h groups (P> 0.05); 1h,2h,4h and 6h groups survival rate in 7d after MCAO were 66.7%(6/9),46.2%(6/13),35.3%(6/17), 16.0%(4/25), respectively. In which 1h group and 2h group survival rate are significant less than 6h group (P<0.05); The percentage of four groups infarct size were (0.1139±0.0122)%, (0.2279±0.0309)%, (0.2509±0.0229)%, (0.2839±0.0220)%, respectively. The major infarction area of 1h group is cortex,2h,4h and 6h groups major infarction area are cortex and basal ganglia. In which,2h and 4h groups infarct size significant less than 6h group (P<0.05), there were no significantly differences at all other groups.Conclusion:1. Longa method made MCAO model the best time reperfusion is 2h;2. It is simple, stability, controllability and repeatability use Longa method made MCAO model. PartⅡCorrelation between the GFAP, NSE, SYN and Nogo-A expression and neurological outcome during the recovery after MCAO in ratsObjective:To investigate the correlation between the glial fibrillary acidic protein (GFAP), neuron-specific enolase (NSE), synaptophysin (SYN), neurite outgrowth inhibitor-A (Nogo-A) expression and neurological outcome in tissue surrounding the infarct during the recovery after cerebral ischemia-reperfusion injury in rats.Methods:24 Sprague-Dawley rats were subjected to 2-hour MCAO, Rats randomly divided into 28d (n = 7),35d (n = 5),42d (n = 6),49d (n = 8) groups. The modified neurological severity score (mNSS) was performed at day 28,35,42,49. Immunohistochemistry was used to detect the expressions of GFAP, NSE, SYN, and Nogo-A in tissue surrounding the infarct.Resutls:The mNSS score decreased gradually over time after cerebral ischemia-reperfusion injury in rats. Except 35d group (5.11±0.737) vs.42d group(4.54±0.519), and 42 group vs.49 group(4.29±0.488), there were significant differences at all other time points (all P<0.05). The numbers of GFAP positive cells decreased gradually form 28d group to 49d group, in which, the numbers of GFAP positive cells at 42d group (51.00±13.59) vs.49d group (44.38±11.94) were significantly less than those at 28 group (69.00±15.10)(P<0.05).There were no significant differences in the numbers of NSE positive cells at all time points, but their integrated optical density (IOD) increased gradually. There were significant differences between 28d group (6218.57±1864.25) and 42d group(9414.00±2491.12) or 49d group (12522.50±3106.99), and between 35d group and 49d group(all P<0.05). There were no significant differences at all other time points. The SYN express (IOD) increased gradually, and it was significantly lower at 49d group (66503.00±12834.61) than that at 28d group (43905.14±13208.59)(P<0.05). The numbers of Nogo-A positive cells decreased gradually, and they were significantly less at 49d group(42.13±14.45) than those at 28d group (59.57±15.25) (P<0.05). The GFAP expression was positively correlated with the mNSS scores (r=0.993, P=0.007).The NSE (r=-0.954, P=0.044) and SYN (r=-0.992, P=0.008) expression was negatively correlated with the mNSS scores.Conclusion:1.The decreased GFAP positive cell numbers and increased SYN,NSE IOD are corelation with neurological function recovery in rats after MCAO; 2. The function of reactive astrogliosis in cerebral infarction may change in different stages.