Retinal Ischemia:Xuefu Zhuyu Decoction’s Effect And Therapeutic Mechanisms

PurposeRetinal ischemia plays a pivotal role in vision threatening ocular retinal disorders,such as central retinal artery/vein occlusion（CRAO/CRVO）,branch retinal artery/vein occlusion（BRAO/BRVO）,age related macular degeneration（AMD）,glaucoma,diabetic retinopathy（DR）etc.Retina ischemia followed by reperfusion causes severe late degeneration of inner retinal structure,especially retinal ganglion cells（RGCs）death.Excitotoxicity,inflammation,activation of signal pathways,apoptosis,and oxidative stress are believed to be the major mechanisms underlying I/R.In this study we investigated the protective effects and therapeutic mechanisms of XFZYD on HIOP-induced retinal ischemia.MethodsHigh intraocular pressure-induced retinal ischemia was established by raising intraocular pressure（IOP）to 120 mmHg for 60 minutes in a Wistar rat eye.This ischemic insult is followed by 1 or 7 days of reperfusion.According to the different treatment,the rats were divided into 4 groups:Normal,Sham,I/R,and drug.Moreover,drug administration involved two groups:pre-ischemic administration(pre-administration:high dose of XFZYD,XFZYD_2.7+I/R,2.7 g/kg/day;low dose of XFZYD,XFZYD_1.35+I/R,1.35 g/kg/day was given for consecutive 7 days)and post-ischemic administration(post-administration:high dose of XFZYD,I/R+XFZYD_2.7,2.7 g/kg/day,was given for consecutive 7 days).The methods included Flash ERG measurement,real-time PCR technique,Western bolt assay,Retrograde labeling of RGCs,Crystal Violet Staining and Immunofluorescence analysis.ResultsThe HIOP-induced retinal ischemic changes were characterized by a decrease in ERG b-wave amplitudes,a decrease in inner retinal thickness,less numerous retinal ganglion cells,a decrease in choline acetyltransferase（ChAT）immunolabeling and an increase in vimentin immunolabeling.Moreover,the increases in both the RNA and protein levels of VEGF,PKM2 and/or HIF-1αwere found in the ischemic retina,respectively.Importantly,the ischemic detrimental effects were concentration-dependent（weaker effect at lower dose）and significantly（at both lower dose and higher dose）altered when XFZYD was applied 7consecutive days before retina ischemia.Besides,the ischemic detrimental effects also can be altered when XFZYD（higher dose）was applied 7 consecutive days after retina ischemia.The protective effects of XFZYD on HIOP-induced retinal ischemia show an increase in ERG b-wave amplitudes,an increase in inner retinal thickness,more numerous retinal ganglion cells,an increase in ChAT immunolabeling and a decrease in vimentin immunolabeling.And pre/post-treatment with XFZYD causes a significant reduction in the RNA and protein levels of VEGF,PKM2 and/or HIF-1α.ConclusionOf clinical importance,XFZYD could have a protective effect on retinal ischemia by decreasing the expression of VEGF,PKM2 and/or HIF-1α.Pre-administration of XFZYD(at 1.35 g/kg/day,XFZYD_1.35+I/R;at 2.7 g/kg/day,XFZYD_2.7+I/R)for consecutive 7days counteracted the ischemia effects in a dose-responsive manner.And the effect of pre-administered XFZYD was greater than that of post-administered XFZYD.