Expression Of P-STAT3 And MMP-9 In Rat Retina Following Acute High Intraocular Pressure

Object To detect the expression of phosphorylated STAT3(p-STAT3) and matrix metalloproteinase-9 (MMP-9) in rat retina following acute high intraocular pressure(HIOP) . To investigate the relationships between p-STAT3,MMP-9 and loss of retinal ganglion cells.Methods A total number of 35 Adult Sprague-Dawley rats weighing 250g were obtained from the Laboratory Animal Unit, Shandong University. They were randomly divided into 5 groups( 6h, 12h, 24h, 48h and 72h groups), seven for each group. Choose one eye for the surgery, and the other eye was used as control.The rats were killed by intraperitoneal injection of 1% sodium pentobarbital(30mg.kg-1), The models of acute ocular hypertension were made by perfusing 0.9% normal saline into anterior chambers of rat's eyes. animals were allowed to survive for 6h,12h, 24h,48h,72hours(n=7 per time point). After perfusion with 4% paraformaldehyde,the eyes were removed and processed for paraffin sectioning. Immunohistochemical technique was used to detect the expression of MMP-9 and p-STAT3 , and the own control group was established at the same time. Retinal sections were stained for p-STAT3 and MMP-9,The secondary antibodies goat-anti-rabbit IgG were used for visualizing p-STAT3 and MMP-9,respectively, and diaminabenzidine(0.05 % )was used as the chromogen(DAB powder). Quantitative analysis of expression of MMP-9 and p-STAT3 were assessed by measuring the Average optical density value of retina tissue with LEICA IM 50 Color Pathologic Analysis System. Statistic analysis:Continuous variables are reported as mean±standard deviation(SD) and have been analysed by SPSS13.0.Continuous variables have been compared using One-way ANOVA, which was followed by t test. For all analysis,a P value less than 0.05 was considered significant.Results 1. Weak signals for STAT3 and MMP-9 were observed in the normal group.2. p-STAT3 positive expressiong was detected at HIOP 6 hours,peaked at 12 hours,then dropped gradually afterwards. Immunostaining for p-STAT3 in retinal ganglion cell layer(GCL),inner nuclear layer(INL).3.MMP-9 positive expressiong was detected at HIOP 6 hours, peaked at 24 hours, then dropped gradually afterwards. Immunostaining for MMP-9 in the inner plexiform layer (IPL) and ganglion cell layer(GCL).Conclusion 1 .p-STAT3 and MMP-9 was involved in the pathological changes in the retina after transaction of acute high intraocular pressure.2.JAK-STAT signaling could be one of the important pathways in the acute high intraocular pressure3. The positive expression level of p-STAT3 and MMP-9 may correlate with losing of retinal ganglion cells.