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Published on: October 23, 2020
Prevention of diabetic retinopathy in a rat model by a functional food mix
Krishna Kalyan Kalahasti1, Pandarinath Savitikadi1, Ch Uday Kumar1
1Biochemistry Division, ICMR-National Institute of Nutrition, Hyderabad, 500007, India.
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.
Insights
A functional food mix effectively combats diabetic retinopathy (DR) progression in rats by reducing inflammation, hypoxia, and cell death. This dietary intervention shows promise for managing DR, a leading cause of blindness.
Area of Science:
- Ophthalmology
- Endocrinology
- Nutritional Science
Background:
- Diabetic retinopathy (DR) is a major cause of blindness, stemming from diabetes-induced hyperglycemia.
- Hyperglycemia triggers vascular damage, inflammation, and cell death in the retina via mechanisms like aldose reductase activity.
- Previous research indicated functional foods can inhibit these pathways, prompting this study on a novel mix.
Purpose of the Study:
- To investigate the efficacy of a functional food (FF) mix against diabetic retinopathy progression.
- To evaluate the FF mix's impact on retinal function, structure, and key molecular markers in a diabetic rat model.
- To explore the synergistic effects of amla, turmeric, ginger, cinnamon, and black pepper in mitigating DR.
Main Methods:
- A functional food mix (FF) was prepared from amla, turmeric, ginger, cinnamon, and black pepper.
- Sprague-Dawley rats were induced with diabetes and fed the FF mix at two dosages for six months.
- Retinal function (electroretinography), histology, immunohistochemistry, and immunoblotting were analyzed.
Main Results:
- FF mix supplementation improved retinal function and prevented photoreceptor cell loss in diabetic rats.
- The FF mix reduced hyperglycemia-induced angiogenesis and gliosis.
- Significant decreases in inflammation and apoptosis markers were observed in FF-treated diabetic rats.
Conclusions:
- The functional food mix demonstrates significant potential in alleviating diabetic retinopathy progression.
- Synergistic effects of the FF mix components combat diabetes-induced retinal hypoxia, gliosis, and inflammation.
- The FF mix inhibits apoptosis in retinal cells, offering a novel therapeutic avenue for DR management.
