Bovine retinal pericytes are resistant to glucose-induced oxidative stress in vitro

Diabetic retinopathy is a sight-threatening complication of diabetes, and loss of pericytes represents early signs of its development. We tested the hypothesis that high glucose levels may induce signs of oxidative stress in cultured bovine retinal pericytes. Pericytes were exposed to either normal (5.5 mM) or high (22 mM) glucose levels for 1, 3, and 5 days. Signs of oxidative stress were measured by expression of copper/zinc superoxide dismutase, manganese superoxide dismutase, catalase, and glutathione peroxidase using real-time RTPCR. To elucidate the role of oxidative stress, we also measured glutathione (GSH) concentration in the cells and investigated the impact of thiol-reactive metal ions and hydrogen peroxide (H2O2) on intracellular GSH. Despite the stimulation with high glucose, thiol-reactive metal ions, or H2O2, there was no clear increased expression of antioxidant enzymes or influence of GSH levels. Lipid peroxidation (malondialdehyde level) was increased in bovine aortic smooth muscle cells, but not in bovine retinal pericytes. The data indicate that pericytes do not develop oxidative stress in response to hyperglycemia. However, it is not definitively excluded that oxidative stress may occur after longer time periods of glucose stimulation.