An Experimental Study On The Retinal Pathological Changes After Severe Alkali Burn Of Cornea In Rats

Objective: To investigate retinal pathological changes and whether apoptosis was involved in it after severe corneal alkali burn. To examination the expression of Fas and FasL and the contents of MDA and the activity of SOD in the retina. To inquire the prima facie mechanism in the pathological process. Metho d s : 41 healthy Wistar rats were randomly divided into 2 groups: experimental and control groups. A model of seve re corneal alkali burn was established in both eyes of 3 5 Wistar rats. Six r ats were executed respectively on the 1 st , 3 rd , 7 th , 1 5th , and 30th d ay a fter the burning, and both eyes were enucleated. H istologic sections of paraffin - embedded retinas in one ey e were stained by HE for pathologic examination, by TUNEL method for detection of apoptosis and by immunohistochemical 4 technique for detection of Fas and FasL. Retinal histologic homogenate in the other eye was made for detection of MDA and SOD. The data w as analyzed statistically with SPSS10.0 software. Results: 1.HE staining: Edema, degeneration and necrosis with infiltrating inflammatory cell s existed in the inner retina after severe alkali burn of cornea in rats. 2.TUNEL staining: TUNEL positive cells were not found in normal retina. A higher number of TUNEL positive cells in the vascular endothelium and the ganglion cell and inner nuclear layers was observed on the 3rd, 7th, 15th, and 30th day after alkali burn ( P ＜ 0.0 1 ) . 3 .Fas and FasL proteins immunohistochemical labeling: Positive immunolabeling for Fas protein was not found in normal retina. The Fas expression in the retina was gradually increased during 1 - 7d after alkali burn, and maintained on a relatively high level in 7 - 30d. FasL was expressed in normal retina. The FasL expression after alkali burn was significantly higher than that ( P ＜ 0.0 1 ) in the control group . Analyzed with the correlation coefficient, there was a remarkable positive correlation between T UNEL positive cells and Fas or FasL ( P ＜ 0.01 ) in the retina after alkali burn. 4.Detection of MDA and SOD: MDA increased gradually from 1 to 7 days after severe alkali burn of cornea in rats, and then dropped gradually. SOD decreased gradually from 1 to 7 day s, and then increased gradually. The contents of MDA in the retina on the 1st, 3rd and 7 th day after the burning was significantly higher than that ( P ＜ 0.0 1 or 0.05 ) in the control group and the activity of SOD on the 1st , 3rd,7th and 15 th day after the burni ng was lower than that ( P ＜ 0.0 1 or 0.05 ) in the control group. The correlation coefficient of MDA and apoptosis was 0. 482 ( P ＜ 0.0 5 ) , and that of SOD and apoptosis was － 0.625 ( P ＜ 0.01 ) except for the data which would induce cell degeneration and necrosis recorded on the 1 st ,3 rd and 7 th day after the burning. Conclusion: Apoptosis and necrosis existed in the...