Abstract
Diabetic retinopathy (DR) is a debilitating diabetic disorder of the retinal microvasculature and the main cause of avoidable blindness in old people. Hesperetin is a plant flavanone largely abundant in citrus species with neuroprotective properties in animal models. This study aimed to explore the neuroprotective and autophagy-enhancing effect of hesperetin in rats with DR. Twenty-four male rats were utilized and allocated to groups: (i) the vehicle group, (ii) DR group and (iii-iv) the DR + hesperetin (50 and 100 mg/kg) groups. Treatment with hesperetin continued for 6 weeks. After the rats were euthanized, their eyes were dissected to detect the biochemical and histological changes in the retinas. Quantification of autophagy markers, beclin 1/LC3/p62, and inflammation markers was performed. Histopathologic changes were investigated after staining with hematoxylin and eosin and periodic acid-Schiff (PAS). Results demonstrated that hesperetin decreased the PAS staining in diabetic rats and attenuated histopathological changes and restored retinal organization and thickness of layers in hematoxylin and eosin staining. Moreover, hesperetin reduced the level of mRNA expression for TNF-α (4.9-fold), IL-1β (4.15-fold), IL-6 (4.6-fold) and NFκB (5.2-fold), as well as the protein level. This was accompanied by induction of autophagy proteins, beclin 1 and LC3-II. Our results afford evidence that hesperetin is effective in alleviating the pathology of DR via suppressing the inflammatory burden and induction of autophagy. After extensive clinical examinations, hesperetin may prove to be a useful option for treatment of DR.