RESUMO
Background Research demonstrated that mitochondrial pathway plays a key role in cell apoptosis.Purendan supermicropowder(PRD),a traditional Chinese medicine,may be a potentially effective therapy for neuron apoptosis in diabetic retina.Objective This study was carried out to investigate the effects of PRD on aldose reductase(AR)activity,neuron apoptosis and mitochondrial pathway in retina of diabetic rat.Methods Thirty-six clean male Wistar rats were randomly divided into normal control group,diabetes model group,PRD treatment group randomly and 12 rats for each group.The diabetes models were established by intraperitoneal injection of 25 mg/(kg · d)streptozotocin(STZ)for 3 consecutive days,and blood glucose ≥ 16.7 mmol/L was taken as the standard.PRD solution of 1.8 g/(kg · d)was lavaged in 12 models for 3 months.The eyeballs were enucleated for the preparation of retinal tissue homogenate and slice.AR activity in the retina was detected by ultraviolet spectrophotometry,and neuron apoptosis in retina was assayed by TUNEL staining.Western blot was used to assess the expressions of bcl-2,bax,cyt-c and caspase-3 protein in the retina.The use of animals followed the Regulations for the Administration of Affair Concerning Experimental Animals by State Science and Technology Committee(Version 1988).Results Statistically significant differences were found in AR activity and AI among the normal control group,diabetic group and PRD groups(F=90.115,165.540,P＜0.01),and those of diabetic group were evidently higher than the normal control group and PRD group(P＜0.01,P＜0.01).The positive TUNEL cells mainly located in inner nuclear layer and retinal ganglion cell layer.The expressions of bax,cyt-c,caspase-3,bcl-2 and bcl-2/bax in retina were obviously different among these three groups(F =51.332,41.262,25.888,38.564,47.870,P＜0.01),and the expression of bax,cyt-c and caspase-3 protein in diabetic group evidently elevated in comparison with the normal control group and PRD group(t ＝ 10.32,11.04,6.91,P ＜ 0.01)and the expressions of bcl-2 protein and bcl-2/bax value were significantly lower in diabetic rats than in the normal control rats(t =18.05,12.23,P＜0.01).AR activity by AI of retina,the expressions of bax,cyt-c and caspase-3 proteins in retina were obviously lower in PRD group than in diabetes model rats(P ＜ 0.01),and the expression of bcl-2 protein and bcl-2/bax value were significantly higher in PRD group than in diabetes group(P＜0.01).Conclusions PRD can protect retina against the damage caused by high glucose by suppressing AR activity by downregulating the expressions of bax,cyt-c,caspase-3 proteins,increasing the expressions of bcl-2 protein in retina of diabetic rats and further inhibiting the mitochondrial pathway and reducing cell apoptosis in retina of diabetic rats.