Purpose Diabetic retinopathy (DR), a severe microvascular complication of both type 1 and type 2 diabetes, is one of the leading causes of blindness. Prolonged hyperglycemia leads to vascular endothelial changes, inflammation, neovascularization, and apoptosis through multiple mechanisms, including increased aldose reductase (AR) activity and formation of advanced glycation end products, which contribute to the development of DR. Based on our previous studies with various functional foods that showed AR inhibition and prevented the formation of advanced glycation end products, in this study, a functional food (FF) mix was formulated and investigated its efficacy against DR progression in a rat model. Methods An FF mix was prepared with powders of amla pericarp, turmeric rhizome, ginger rhizome, cinnamon bark, and black pepper seeds in a specific proportion. Two-month-old Sprague-Dawley rats were grouped into control (C), streptozotocin-induced diabetes (D), and diabetes fed with FF at two levels (FF1, 0.85 g/100 g diet; FF2, 4.25 g/100 g diet) for 6 months from the induction of diabetes. At the end of the experiment, electroretinography was performed, and the eyes were dissected after the animals were sacrificed. A set of eyes was formalin-fixed for histology and immunohistochemistry examination, and the retina from the remaining eyes was used for immunoblotting analysis. Results Supplementation of FF mix in the diet to diabetic rats has improved retinal function (electroretinography), as well as prevented histomorphological changes and loss of photoreceptor cells (rhodopsin), compared to untreated diabetic rats. Further, FF mix ameliorated hyperglycemia-induced angiogenesis (vascular endothelial growth factor, hypoxia-inducible factor 1α) and gliosis (glial fibrillary acidic protein) in the diabetic rats, accompanied by decreased inflammation (phosphorylated nuclear factor κB, tumor necrosis factor α, monocyte chemoattractant protein 1) and apoptosis (Bax, Bcl2, caspase3, and caspase12). Conclusions This study illustrates the potential of an FF mix, attributed to the synergistic effects of its components, alleviating the progression of diabetic retinopathy by reducing diabetes-induced hypoxia, gliosis, and inflammation, while also inhibiting apoptosis in retinal cells.
Kalahasti et al. (Sat,) studied this question.