thiobarbituric-acid and Diabetic-Retinopathy

Placebo for 3 months, followed by 30 mg/day zinc gluconate in identical capsules.. Diabetic out patients clinic at the University Hospital, Grenoble.. Diabetic patients cared for type I diabetes mellitus. 22 patients began the study, 4 dropped out. 10 patients suffered of an early retinopathy, 8 patients had no retinopathy.. In this order: T0 biological measurements, 3 months placebo treatment, T1 biological measurements, 3 months zinc gluconate treatment, T2 biological measurements. Plasma Zn, Cu, Se, thiobarbituric acid reactants and antioxidant enzymes were measured [plasma and red glutathione peroxidase (Se-GPx), red cell superoxide dismutase (Cu-Zn-SOD)].. Lower plasma zinc level in the two groups. An increase in zinc level was observed and was more important in diabetic patients with no retinopathy (P = 0.05). The thiobarbituric acid reactants were above the reference values in all the patients, and were decreased at T2 (P < 0.05). Increase of GPx activity after zinc supplementation in patients with retinopathy.. Zinc deficiency in insulin-dependent diabetic patients is corrected by a zinc supplementation. Moreover this supplementation decreases lipid peroxidation. The effects of zinc are different in diabetic patients with or without retinopathy. The increase in Se-GPx activity observed in patients with retinopathy could be linked to the protective effect of zinc on the protein itself.

Topics: Adult; Copper; Diabetes Mellitus, Type 1; Diabetic Retinopathy; Female; Gluconates; Glutathione Peroxidase; Humans; Lipid Peroxidation; Male; Selenium; Superoxide Dismutase; Thiobarbiturates; Zinc

Diabetic retinopathy (DR) is a leading cause of acquired blindness in adults, mostly affected by type 2 diabetes mellitus (T2DM). We have developed an experimental model of early T2DM in adult rats which mimics some features of human T2DM at its initial stages and provokes significant retinal alterations. The aim of this work was to analyze the effect of melatonin on retinal changes induced by the moderate metabolic derangement. For this purpose, adult male Wistar rats received a control diet or 30% sucrose in the drinking water. Three weeks after this treatment, animals were injected with vehicle or streptozotocin (STZ, 25 mg/kg). One day or 3 wk after vehicle or STZ injection, animals were subcutaneously implanted with a pellet of melatonin. Fasting and postprandial glycemia, and glucose, and insulin tolerance tests were analyzed. At 12 wk of treatment, animals which received a sucrose-enriched diet and STZ showed significant differences in metabolic tests, as compared with control groups. Melatonin, which did not affect glucose metabolism in control or diabetic rats, prevented the decrease in the electroretinogram a-wave, b-wave, and oscillatory potential amplitude, and the increase in retinal lipid peroxidation, NOS activity, TNFα, Müller cells glial fibrillary acidic protein, and vascular endothelial growth factor levels. In addition, melatonin prevented the decrease in retinal catalase activity. These results indicate that melatonin protected the retina from the alterations observed in an experimental model of DR associated with type 2 diabetes.

Topics: Animals; Catalase; Diabetes Mellitus, Type 2; Diabetic Retinopathy; Electroretinography; Glucose; Immunohistochemistry; Male; Melatonin; Rats; Rats, Wistar; Thiobarbiturates; Tumor Necrosis Factor-alpha

Using the streptozotocin (STZ)-induced diabetic rat model, we have established a time-related curve for lipid hydroperoxides (LHP) in plasma and have correlated the period corresponding to maximal increase with histologic changes in the outer retina. Measurement of thiobarbituric acid reacting substances (TBARS) provides a convenient assessment of LHP concentration in plasma. Our results demonstrate a seven-fold elevation of TBARS at 10 days post-induction which increased to fifteen times above normal at 22 days and then fell dramatically to below baseline values at 39 days. Structural damage to the retina consisted of a reduction in cell number throughout the inner and outer nuclear layers, disorganization and loss of photoreceptor segments, and dilation of the basal region of the retinal pigment epithelium. The present observations establish a correlation between LHP concentration and retinal structure and function. Taken together with other reports in the literature showing alterations of protective enzymes and antioxidants, it appears that free radicals and lipid peroxidation are involved in the etiology of diabetic retinopathy in the STZ rat model. The TBARS assay is a simple, sensitive and inexpensive method to monitor changes in oxidative status and may prove useful in diagnosis and monitoring of patients with diabetes.

Topics: Animals; Diabetes Mellitus, Experimental; Diabetic Retinopathy; Indicators and Reagents; Lipid Peroxidation; Male; Rats; Rats, Inbred Strains; Retina; Thiobarbiturates

Increased levels of lipid peroxides have been implicated in the pathogenesis of diabetic complications. A convenient and sensitive method for estimation of lipid peroxide concentration is the quantitative estimation of their metabolic end-product malonyldialdehyde (MDA) expressed in mumol/L using the thiobarbituric acid test. The mean fasting MDA value in the plasma of 26 Arab subjects with NIDDM was significantly higher than in healthy controls (14.3 +/- 8.3 vs 2.3 +/- 3.4, p less than 0.001). Within a group of nine diabetic patients with markedly elevated MDA values (greater than 20 mumol/L), eight subjects had retinal changes, four had evidence of coronary artery disease and three had manifest cerebrovascular disease. Macroproteinuria was documented in only three patients in this same group. The mean body mass index was 28.7 +/- 5.4 and the glycaemic control was unsatisfactory with a mean glycosylated hemoglobin of 10.1 +/- 1.5%. The MDA results in an Arabic population were similar to reports in Japanese and British patients and should prove useful as a laboratory test in assessing the severity of the diabetic state, as well as a complementary test in diagnosis and management.

Topics: Diabetes Mellitus, Type 2; Diabetic Retinopathy; Female; Humans; Indicators and Reagents; Kuwait; Lipid Peroxidation; Male; Malondialdehyde; Middle Aged; Reference Values; Regression Analysis; Thiobarbiturates