Nobiletin ameliorates streptozotocin induced diabetic retinopathy in experimental rats

Prolonged hyperglycemia in diabetes mellitus results in severe vascular complications leading to decrease in longevity of affected individuals. Diabetic retinopathy is a major cause of blindness in diabetes. Nobiletin is a polymethoxyflavone present in high concentration in citrus fruits. Here we have evaluated the treatment with nobiletin on the amelioration of diabetic retinopathy in STZ-induced diabetic rats. Diabetes was induced by a single intraperitoneal administration of STZ (50 mg/kg). Animals with blood glucose levels >350mg/dL after 48 hours of STZ injection were subjected to further treatments. Diabetic rats were treated daily with nobiletin (10 mg/kg and 25 mg/kg) for four weeks after four weeks of induction of diabetes. At the end of eight weeks, blood retinal barrier permeability was quantified in animals treated with nobiletin and compared with that of vehicle control. Histopathological analysis of the retinal sections was done using H&E stain and the outer limiting membrane to inner limiting membrane distance was measured. Further, outer nuclear membrane thickness was compared between the treatment groups. The study suggested that nobiletin reduced blood retinal barrier permeability and improved the thickness of retinal layers. Thus, treatment with nobiletin can be used as an approach to ameliorate diabetic retinopathy.