Testicular oxidative damage and role of combined antioxidant supplementation in experimental diabetic rats

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The present study was designated to assess oxidative damage and its effect on germ cell apoptosis in testes of streptozotocin (STZ)-induced diabetic rats. The role of antioxidant supplementation with a mixture of vitamins E and C and alpha lipoic acid for protection against such damage was also evaluated. Forty-five adult male rats were randomly divided into three groups: group I, control, non-diabetic rats; group II, STZ-induced, untreated diabetic rats; group III, STZ-induced diabetic rats supplemented with a mixture of vitamins E and C and alpha lipoic acid. Glycated hemoglobin (HbA1C), glucose, and insulin levels were estimated in blood samples. Malondialdehyde (MDA), the activities of the enzymes superoxide dismutase (SOD), glutathione peroxidase (GPx), and caspase-3 in addition to testosterone (T) level were all determined in testicular tissues. Histopathological studies using H&E stain, as well as, immunohistochemical detection of apoptosis using (TUNEL) method were also performed. Blood glucose and HbA1c were significantly increased while insulin was significantly decreased in STZ-induced diabetic rats as compared with controls. In rat testicular tissues, MDA, and caspase-3 activity were significantly elevated while SOD and GPx enzymatic activities as well as T level were significantly decreased in diabetic rats as compared with control group. Antioxidant supplementation to diabetic rats restored the testicular enzymatic activities of SOD and GPx to almost control levels, in addition, MDA and caspase-3 activity decrease while T increase significantly as compared with untreated diabetic group. Prominent reduction of germ cell apoptosis was found in diabetic rats supplemented with antioxidants. An important role of testicular oxidative damage and germ cell apoptosis in diabetes-induced infertility could be suggested, treatment with antioxidants has a protective effect by restoring SOD and GPx antioxidant enzymatic activity (AU)

Actualidad del selenio en la alimentación / Role of selenium in nutrition

Desde que en los años 70 se demuestra cómo el Selenio (Se) es parte integral de la enzimaglutation peroxidasa –enzima que protege a las células de los radicales libres– han sido muchos los estudios que evidencian la importancia que tiene este mineral para el organismo. La única fuente de Se para el hombre es la dieta. Por ello, es importante seguir una alimentación adecuada desde la infancia para cubrir las necesidades de este mineral (AU)

A great number of reviews have evidenced the importance of selenium for our organism since it was proved to be an integral part of the enzyme glutathione peroxidase, which protect tissues from oxidative break down. Diet is the only source of selenium. Therefore, an adequate nourishment from childhood is important in order to cover our need of this mineral (AU)

Adsorption of a phospholipid-hydroperoxide glutathione peroxidase into phospholipid monolayers at the air-water interface.

The interfacial behavior differences of two glutathione peroxidase isoforms have been investigated. The first isoform is the phospholipid-hydroperoxide glutathione peroxidase (EC 1.11.1.12) (GPx-4) isolated from rat testes and the second one is the cytosolic glutathione peroxidase (EC 1.11.1.9) (GPx-1) from bovine erythrocytes. Injected in the subphase buffer of a Langmuir trough, GPx-4 was able to adsorb quickly at the air-water interface whereas the GPx-1 was not. Then, the protein interaction with phospholipid monolayers was explored. Indeed, a monolayer of phospholipids containing a different number of polyunsaturated fatty acyl chains was prepared at the air-water interface. Under each kind of monolayer, the protein solution was injected and its adsorption was visualized by the measurement of successive pressure-area isotherms. We have, then, determined the molecular area increase due to the protein adsorption. It was found that the GPx-4 is adsorbed in each kind of monolayer tested whereas no molecular area increase was detected with the GPx-1. This indicates that the GPx-4 has a higher affinity for the interface, recovered or not by lipids, than the GPx-1. Moreover, the GPx-4 presents a different affinity for the phospholipid monolayers depending on the number of polyunsaturated fatty acyl chains.

Prophylactic action of melatonin against cyclophosphamide-induced oxidative stress in mice.

The present study investigated the prophylactic influence of melatonin against cyclophosphamide-induced oxidative stress in mouse tissues. Lipid peroxidation, reduced glutathione (GSH), glutathione disulphide (GSSG), glutathione peroxidase (GSH-Px) and serum phosphatase levels were analyzed in brain, spleen liver, lungs, kidney and testes. Fifteen days oral administration with melatonin (0.1 mg/kg bw per day) before treatment checked the augmentation of the level of lipid peroxidation, blood GSSG and acid phosphatase caused by an acute treatment with a radiomimetic drug, cyclophosphamide (75 mg/kg bw). Cyclophosphamide-induced depletion in the level of GSH, GSH-Px and alkaline phosphatase was made up statistically significant by chronic melatonin administration given orally. The results indicate the antioxidative properties of melatonin resulting into its prophylactic property against the cyclophosphamide-induced biochemical alterations. The finding support the idea that melatonin is a potent free-radical scavenger and antioxidant.

Glutathione reductase, selenium-dependent glutathione peroxidase, glutathione levels, and lipid peroxidation in freshwater bivalves, Unio tumidus, as biomarkers of aquatic contamination in field studies.

The aim of this study was to evaluate the usefulness of antioxidant parameters in the freshwater bivalve, Unio tumidus, as biomarkers of exposure to pollutants and to study their potential interest in predicting toxicity. Selenium-dependent glutathione peroxidase (Se-GPx), non-selenium-dependent glutathione peroxidase (non-Se-GPx), glutathione reductase (GRd), catalase, and superoxide dismutase (SOD) activities; reduced (GSH) and oxidized (GSSG) glutathione levels; and lipid peroxidation were measured in the gills and digestive glands of Unio. Control mussels were encaged and transplanted for 15 and 30 days to sites where the contamination of sediments was analyzed, along a river receiving domestic and industrial sources of pollution. After 15 days of exposure, all antioxidant parameters of the bivalves transferred to the most polluted sites had strongly decreased compared with control values. This was particularly true for Se-GPx and GRd activities, which were inhibited by 60 and 80% in the two tissues, and for GSH levels (80% reduction in the gills and 60% in digestive glands). These decreases were associated in the gills with lipid peroxidation (measured by malondialdehyde content) and with a high level of contamination of sediments by polycyclic aromatic hydrocarbons and polychlorinated biphenyls. In the mussels exposed at the least polluted sites, the same parameters decreased in the gills, but to a lesser extent: 50% for Se-GPx and 32% for GRd activities, and 45% for GSH levels. The gills appeared more sensitive than the digestive glands. After 30 days of exposure, while Se-GPx, GRd, and GSH remained reduced, a significant induction of non-Se-GPx and catalase activities was recorded in the gills, which reflected an adaptation of the transplanted species to their unsafe environment. All the results indicated that antioxidant defense components, namely, Se-GPx, GRd, and GSH, are sensitive parameters that could be useful biomarkers for the evaluation of contaminated aquatic ecosystems. The relationship between the degree of deficiency of antioxidant defenses and lipid peroxidation suggests that these parameters could also be biomarkers for toxicity.

Effect of ethanol in vivo on enzymes which detoxify oxygen free radicals.

The effects of ethanol administered as a 15% solution in drinking fluid on weight gain, soluble liver protein and the activity of the three enzymes of oxygen radical metabolism (i.e., superoxide dismutase, catalase, and glutathione peroxidase) were studied in five inbred strains of mice (129/ReJ, BALB/c, C3H/HeSnJ, C57BL/6J, Csb) and Sprague Dawley rats, relative to age, sex, and genotype matched controls. Animals maintained on ethanol exhibited lower weight gains and elevation of soluble liver protein than controls. Total superoxide dismutase, catalase and glutathione peroxidase activity in ethanol-treated animals were in general reduced in comparison to that of their matched controls, with each strain showing genotype specific enzyme activity. Such ethanol feeding results are attributed to the direct and indirect effects of this treatment protocol and raise the possibility that ethanol-fed animals may be susceptible to free radical damage and at least some of the cellular damages observed following ethanol challenges could be attributed to the reduced level of these protective enzymes.

Anti-inflammatory effect of glutathione peroxidase on experimental lens-induced uveitis.

An acute lens-induced necrotizing intraocular inflammation was produced in Lewis rats. Treatment of these animals by intraperitoneal injection of glutathione peroxidase resulted in marked decrease in uveal inflammation, retinal edema, hemorrhage and vasculitis. Intraperitoneal injection of glutathione peroxidase resulted in increased levels of this enzyme in ocular tissue. These findings suggest that glutathione peroxidase can modulate acute lens-induced ocular inflammation by serving as a potent anti-inflammatory agent.