tBHQ activates Nrf2 signaling pathways to enhance retinal protection in type 2 diabetic rats / 眼科新进展

ABSTRACT

Objective To study the protective effects of tBHQ on type 2 diabetic rats retina and its related mechanism.Methods Sixty SD rats were divided into normal control group (NC group),model group (diabetes mellitus,DM group) and tBHQ group.After feeding with high fat and high sugar diets for 4 weeks,the rats in model group were induced by intraperitoneal injection of STZ for the model of type 2 diabetes mellitus.1％ tBHQ were added into the high fat and high sugar feed 1 week later after successfully modeled in the tBHQ group.Fasting plasma glucose (FPG) and fasting serum insulin (FINs) were detected at 4 and 12 weeks after modeled.Immunohistochemical method and real-time fluorescent quantitative PCR (qRT-PCR) were respectively used to detect the distributions and relative expression levels of nuclear factor erythroid 2-related factor 2 (Nrf2),heme oxygenase 1 (HO-1),B-cell lymPhoma 2 (Bcl-2) and vascular endothelial growth factor (VEGF) in retinas of the rats.Results FPG levels totally comparative differences were statistically significant between each group (F =78.531,P =0.000).The level of FPG in DM and tBHQ group were obviously higher than that in NC group,the 12 weeks was higher than 4 weeks in DM group,and the 12 weeks was lower than 4 weeks in tBHQ group (all P ＜ 0.05).Totally comparative differences in the level of FINs were statistically significant (F=22.480,P =0.000),NC group was lower than DM and tBHQ group,12 weeks was higher than 4 weeks (all P ＜ 0.05).Immunohistochemical detection showed that each factor in each group were expressed in the retina of rat,and the relative expressions of Nrf2,HO-1,Bcl-2 and VEGF protein in retina have totally statistically differences in different time points after modeled (all P ＜0.05).The expressions of each factor in DM group were more than those in the NC group.The Nrf2,HO-1 and Bcl-2 in tBHQ group were more than those in the DM group,but the VEGF was lower.At 12 weeks,the expressions of VEGF and Nrf2 in DM group were more than those at 4 weeks,but the HO-1 was lower;the Nrf2,HO-1 and Bcl-2 in tBHQ group were more than those at 4 weeks (all P ＜ 0.05).PCR tests revealed that the relative expressions of Nrf2,HO-1,Bcl-2 and VEGF mRNA in retina have totally statistically differences in different time points after modeled(all P ＜ 0.05).The expressions of each factor in DM group were more than those in the NC group.The Nrf2,HO-1 and Bcl-2 mRNA in tBHQ group were more than those in the DM group,but the VEGF mRNA was lower.At 12 weeks,VEGF mRNA in DM group and Nrf2,HO-1,Bcl-2 in tBHQ group were more than those at 4 weeks (all P ＜ 0.05).Conclusion tBHQ maybe have protection for islet function on diabetic rat,and can induce the expressions of Nrf2,HO-1,Bcl-2 in retina of diabetic rats and reduce the expression of VEGF,inhibit the oxidative stress of retinal tissue damage,reduce cell apoptosis and inhibit the proliferation of retinal blood vessels.tBHQ may protect the retina of diabetic rats through the Nrf2/HO-1/VEGF and Nrf2/Bcl-2 way.