Introduction: Diabetes is a metabolic disease that can cause neuropathy, retinopathy and nephropathy. Diabetic retinopathy is one of the main causes of blindness in adults in the world. In this disorder, due to the activation of biochemical pathways related to hyperglycemia and ultimately the increase of oxidative stress factors, inflammation and nerve damage, defects are created in the capillaries of the retina, which will cause vision loss and eventually blindness. Oxidative stress is the result of an imbalance between the production of free radicals and the body's antioxidant defense. Considering the vital role of mitochondria in aerobic metabolism, the function of this organelle is significantly related to the pathophysiology of diabetes. In addition, mitochondria produce reactive oxygen species as a result of fuel oxidation, and these radicals and the oxidative stress caused by them are very important in the pathophysiology of diabetes and its complications. as a result of reducing free radicals and protecting mitochondrial function and using various vitamins and drugs such as angiotensin-converting enzyme inhibitors and sulfonylureas and lipoic acid as well as antioxidant effects in various plants including flavonoids found in plant sources which have been observed in recent years, all of them indicate the very prominent role of oxidative stress in diabetes and its complications.
Methods: Diabetes retinopathy is the cause of blindness among people. Oxidative stress is a phenomenon that is an imbalance between the formation and elimination of free radicals, and we can say that oxidative stress and the production of free radicals as a result of hyperglycemia are involved in the development and complications of diabetes. Although chronic hyperglycemia is an important factor in the development of diabetes complications. There are mechanisms that cause organ dysfunction. One hypothesis is that intracellular glucose causes the production of the final product of glycosylation through non-enzymatic glycosylation of proteins and cells. The second hypothesis is that the cause of chronic complications of diabetes is that hyperglycemia increases glucose metabolism through the sorbitol pathway. The third hypothesis states that hyperglycemia increases the formation of diacylglycerol, which in turn activates protein kinase C. Important growth factors play a role in causing diabetes complications. Vascular endothelial growth factor is increased in diabetic retinopathy. Free radicals play an important role in both health and disease. Free radicals are divided into three types. Hydroxyl, superoxide and peroxide. Most of the radicals are produced by mitochondria and the most radical damage is on the membrane and DNA of mitochondria. Most of the free radicals in the biological system are derived from oxygen (ROS), but there are also derivatives of nitrogen. It has been shown that hyperglycemia, hyperinsulinemia and insulin resistance increase free radical production and oxidative stress in type 2 diabetes. Hyperglycemia can be involved in the development of neuropathy due to oxidative stress through autoxidation of glucose to the formation of AGES, disruption of the polyol pathway, change in eicosanoid metabolism, and reduction of antioxidant defense.
Results: The role of oxidative stress caused by imbalance in the production of free radicals in diabetic retinopathy. ROS such as superoxide radical, hydroxyl radical and hydrogen peroxide radical are very unstable or even very reactive. Excessive production of superoxide radicals, altered mitochondrial electron transport chain reactions, destroys various cell structures.
Conclusion: The purpose of this review is to provide a better understanding of the complex molecular mechanisms and pathogenic roles of oxidative stress in the development of diabetic retinopathy, one of the most common complications of diabetes. Oxidative stress is a cytopathic consequence caused by an imbalance between the production and removal of ROS and seems to play a major role in it. A series of metabolic abnormalities caused by hyperglycemia, including polyol, AGE formation, metabolic pathways accordingly form a vicious cycle that causes cell mitochondrial damage, retinal cell apoptosis, lipid peroxidation, dysregulated epigenetic modification on genes. antioxidant defense system and structural and functional damages in the retina.