Abstract
Abstract: :
Purpose: To determine whether glucose exposure induces signs of oxidative stress in tissue cultured bovine retinal pericytes, i.e. increased lipid peroxidation and activation of the cellular defence system against oxidative stress. Pericytes were chosen since this cell type has been shown to be involved early in the development of diabetic retinopathy. Methods: Peicytes were exposed to normal (5.5 mM) or high (22 mM) glucose for 1, 3 and 5 days in a first series of experiments, and in the presence of hydrogen peroxide (0.1, 1.0, 5.0 micromol/L) or thiol reactive ions like mercury chloride (1, 10 micromol/L) in a second series of experiments. Signs of oxidative stress were assessed by measuring expression of mRNA for the antioxidant enzymes CuZnSOD, MnSOD, catalase and glutathione peroxidase in the first series of experiments using real–time RT–PCR, and glutathione (GSH) concentrations in the second series of experiments using high–performance liquid chromatography. Lipid peroxidation was assessed by measuring the concentration of malonedialdhyde using the BIOXYTECH LPO–586 colorimetric assay kit. Smooth muscle cells were used as positive control. Results: Despite stimulation with high glucose, hydrogen peroxide or thiol reactive metal ions, there was no clear increased expression of anti–oxidative enzymes or influence on GSH levels. Under the same conditions, lipid peroxidation was increased in bovine aortic smooth muscle cells but not in bovine retinal pericytes. Conclusions: Under the experimental conditions used, pericytes do not develop oxidative stress in response to hyperglycemia. Thus, oxidative stress does not seem to be a major cause of pericyte loss in the development of diabetic retinopathy.
Keywords: diabetic retinopathy • oxidation/oxidative or free radical damage