Attenuation of reactive oxygen species (ROS) generation in the cultured retinal cells under high glucose conditions

The excess reactive oxygen species (ROS) formation due to diabetes-induced hyperglycemia is believed to play a central role in the pathophysiology of diabetic complications including diabetic retinopathy. However, the mechanism of excess ROS generation due to hyperglycemia is still uncertain. In this study, we measured ROS levels under the influence of low and hyperglycaemic conditions in the cultured retinal Muller (TR-MUL) and bovine retinal endothelial cells (BRECs) to better elucidate the basis of oxidative stress. The most common fluorescent dye, CM-H(2)DCFDA was used to examine the ROS level in the cultured retinal cells after incubations with high (30 mM) and low glucose (5.5 mM), and treatments with metabolites (pyruvate, glutamate, and glutamine), oxidizing agents (diamide, CuSO4), and endotoxin, lipopolysaccharide (LPS). Our results showed high glucose did not increase ROS levels in both TR-MUL and BRECs cells; on the contrary, high glucose resulted in a significant decrease in ROS levels compared to low glucose (P < 0.05). Diamide and CuSO4 treatment induced a large increase in ROS levels in the TR-MUL cells at low glucose, while high glucose significantly reduced its levels (P < 0.05). Pyruvate and glutamate ameliorated, while glutamine augmented the ROS level in the TR-MUL cells. LPS induced ROS formation, while high glucose incubation significantly reduced its level (p < 0.05). The results of this study do not support the high glucose-induced increase in ROS levels in the cultured retinal cells; rather, high glucose appeared to have ameliorative effects on oxidative stress, induced due to low or euglycemic conditions. (C) 2022 The Author(s). Published by Elsevier B.V. on behalf of King Saud University. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).