Purpose: The aim of this study was to investigate the improved effect of resveratrol (RSV) on early retinal neurodegeneration in diabetic retinopathy (DR) via regulating autophagy/ microRNA-29b (miR-29b)/ specificity protein 1 (SP1)/ apoptosis pathway.
Methods: Retinal tissues from normal rats and diabetic rats after 12 weeks of intervention, and retinal Müller cells (RMCs) from normal and high glucose (HG) cultures, with or without rapamycin (RAPA), 3-methyladenine (3-MA), and RSV treatments, were used. Retinal neurofunctional changes were measured by electroretinogram. Retinal inner nuclear layer cell autophagy changes were detected by transmission electron microscopy. Cell viabilities were measured by CCK-8. The expressions of autophagy proteins light chain 3 (LC3)-I, LC3-II, Beclin-1, P62 and miR-29b, SP1 were detected by qRT-PCR, western blot, immunocytochemistry and ELISA. Apoptosis was detected by TUNEL and ELISA.
Results: In vivo, RSV alleviated diabetes-induced weight loss, inhibited fasting plasma glucose elevation, improved retinal neurofunctional changes, and reversed autophagy inhibition in DM rats. In vitro, RSV increased HG-cultured RMCs viabilities. In vivo and in vitro, the dysregulated expressions of LC3-I, LC3-II, Beclin-1, P62 and miR-29b, SP1 induced by diabetes and HG were significantly inhibited by RSV treatments. RAPA pretreatments enhanced the regulating effects of RSV on miR-29b, SP1 expression and RMCs apoptosis; 3-MA pretreatments inhibited the regulating effects of RSV on miR-29b, SP1 expression and RMCs apoptosis in vivo and in vitro.
Conclusions: Our findings indicated that RSV is a potential therapeutic option for DR and that activating autophagy and further regulating the miR-29b/SP1/apoptosis pathway plays an important role in the anti-DR mechanism of RSV.
Keywords: Autophagy; Diabetic retinopathy; Müller cells; Resveratrol; miR-29b/SP1 axis.
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