大鼠脑挫伤后GFAP和iNOS表达与损伤时间关系的实验研究

目的　观察大鼠实验性脑挫伤后胶质纤维酸性蛋白 (GFAP)和诱导型—氧化氮合成酶 (iNOS)的表达及其时相性的关系 ,试图寻找法医学脑损伤时间的推断方法。方法　建立脑挫伤的动物模型 ,采用免疫组织化学技术 (SABC法 )观察大鼠脑挫伤后GFAP及iNOS在伤后不同时间的表达。染色结果用计算机彩色图像分析技术作定量统计分析处理。结果　 ( 1)伤后 3h时GFAP阳性表达细胞开始增多 ,1d和 5d组单个阳性细胞染色强度达峰值 ,但在 3d组相对邻近组却下降 ,呈现出一双峰波形 ,7d达最大值 ;阳性物质总面积自 3h时表达增多开始后一直增加 ,直到 7d时达高峰。 ( 2 )伤后 12h组可见iNOS活性增高 ,并随伤后存活时间的延长 ,iNOS阳性细胞数目 (或阳性物质总面积 )逐渐增多 ,单个细胞染色强度逐渐加深。伤后 1d至 3d组阳性物质总面积达到高峰 ,5d后开始下降 ,但 7d时仍维持较高水平 ;而单个细胞染色强度随伤后存活时间的延长而加深 ,于 5d时达高峰后显著下降 ,但高于起始水平。结论　脑挫伤后GFAP和iNOS在损伤局部的染色变化有一定的时间规律性 ,可以用于脑挫伤的时间推断。

An experimental study on the relationship between the expression of GFAP and iNOS and the post traumatic intervals after brain contusion in rats

Objective To observe the relationship between the expression of GFAP and iNOS the post-traumatic intervals after experimental cerebral contusion,in order to attempt to find out a method of timing wound age of brain contusion in the forensic prediction of injury time.Methods After setting up an model of experimental focal cerebral contusion in rats,immunohistochemical method was applied to observing the changes of inducible nitric oxide synthase (iNOS) and glial fibrillary acidic protein (GFAP) staining combined with histology method in rats.The immunostaining results were measured quantitatively with computer imaging analysis system.Results (1) At 3h after injury,GFAP-positive astrocytes around the wounded area were definitely detected.The intensity and the area of GFAP-positive cells increased following the post-traumatic intervals.The intensity peaked dually at 1d and 5d,respectively,followed by reduction at 3d,which revealed two-peak waveforms,The area of GFAP positive cells enhanced significantly at 3h and gradually increased with prolonging survival time,and reached a peak at 7d after injury.(2) At 12h after injury,the iNOS isoform was present and iNOS positive staining cells were noted.The intensity and the area of iNOS positive cells increased following the post-traumatic intervals.The area of positive reached maximal level at 1-3days,gradually subsided after 5d,and maintain a higher lever up to 7d post-injury;but the intensity of individual positive cell gradually increased with prolonging survival time,reached a peak at 5d and gradually subsided after 5d,but the level was still higher than the initial interval.Conclusions Expression of GFAP and iNOS is correlated with post-traumatic intervals after cerebral contusion in rats,suggesting that the expression of iNOS and GFAP may be served as the markers for timing of brain contusion in forensic practice.