Protective Effect Of Tat-beclin1 Peptide On Retinal Ganglion Cells In Rats Of Chronic Ocular Hypertension

Purpose:Autophagy plays an important role in the pathophysiology of glaucoma.The aim of this study was to investigate the protective effect and mechanisms of autophagy-inducing peptide Tat-beclin1 on the retinal ganglion cells(RGCs)death in rats with chronic ocular hypertension(COH)rats.Methods:The anterior chamber of right eye of Sprague-Dawley rat was injected with cultured conjunctival fibroblasts(CCFs).Intraocular pressure(IOP)was monitored by Tono-Lab tonometry.One week after COH,the COH eyes were either injected intravitreally with 5μl 100μM Tat-scrambled for the control group,50μM Tat-beclin1,100μM Tat-beclin1 or 200μM Tat-beclin1 for the treatment group,respectively.Eyes were enucleated 2w,4w or 8w after COH.RGCs were retrogradely labeled with FG 1w prior to eye enucleation.RGCs counting were conducted under microscopy.Cell apoptosis of the retina was assessed by TUNEL staining.Expression of cleaved caspase-3,autophagy-related proteins beclin1 and LC3 in the retina were determined using Western blot analysis.Results:After CCFs injection into the anterior chamber,the IOP was raised to 22 to 36 mmHg(mean 27.5mmHg)in the COH eyes and remained elevating for at least 8 weeks,while the IOP remained normal(10 to 15 mmHg,mean 11.4mmHg)in the sham-operated left eyes(P<0.01).The density of RGCs of 50μM Tat-beclin1 group and 100μM Tat-beclin1 group were significantly higher than that of the control group(both P values less than 0.05).However,the RGCs density of 200μM Tat-beclin1 group was lower than that of the Tat-scrambled group(P<0.05).The RGCs density in rats after COH two months were lower than that in rats after one month or two weeks.Retinal staining showed RGCs apoptosis in control and 200μM Tat-beclin1 groups was significantly more than the 50μM Tat-beclin1 group and 100μM Tat-beclin1 groups.Western blot analysis showed that the expression of beclin1 and the ratio of LC3-Ⅱ/LC3-Ⅰ increased in all Tat-beclin1-treated groups.Conclusions:Intravitreal injection of Tat-beclin1 induced autophagy in the retina of rats and played a protective role against RGCs death and apoptosis after COH.The results suggest that autophagy-inducing peptide may have potential effects in glaucoma treatment in the future.