Chronic hydrogen peroxide intake and peroxide metabolizing enzyme activities in some tissues of mice and rats

Chronic daily intake of 0.5% H2O2 in drinking water decreased Se-dependent glutathione peroxidase (Se-GSHPx) activity in rat skeletal muscle, kidney and liver. Non-Se GSHPx activity decreased in kidney. Deprivation of drinking water decreased Se-GSHPx activity in kidney and non-Se GSHPx activity in kidney and liver. H2O2 intake decreased activity of catalase in rat skeletal muscle. H2O2 intake or water deprivation caused no changes in these enzyme activities in mice.     

Plasma growth hormone in the rabbit fetus. Relation to maturation of the liver and lung]

Day 25 after insemination is a date of peculiar importance in the maturation of several organs in the Rabbit fetus. From day 25 onward the fetal liver stores increasing amounts of glycogen and the lung stores increasing amounts of lecithins, concomitant with sudden rise in the activity of lung phosphatidic-acid phosphohydrolase. Earlier studies on decapitated fetuses established that glycogen storage in the liver is dependent on a dual hormonal control, comprising a pituitary hormone like growth hormone or prolactin (some placental hormones share the same activity) and corticosteroids (Jost, 1961). Since the variations in endogenous corticosteroids do not seem to herald these liver or lung changes (Mulay et al., 1973), a study was made of growth hormone. Plasma immunoreactive growth hormone--determined with a heterologous Rat system (Kervran et al., 1976)--increases eightfold between days 23 and 25. During the same time plasma prolactin does not change according to McNeily and Friesen, 1978, and to unpublished data obtained with Dr McNeilly. In preliminary assays, Rat growth hormone was seen to increase phosphorylase "a" activity in the lung of 18.5 day-old Rat fetuses, thus anticipating normal development. We suggest that growth hormone plays a role in initiating liver and lung maturation.     

The effects of vitamin A nutritional status on microsomal lipid peroxidation and alpha-tocopherol level in rat liver

In vitamin A-deficient rats, liver glutathione peroxidase activity was decreased, alpha-tocopherol content was strongly enhanced, but microsomal liquid peroxidation remained unchanged.     

Stimulation of cell division in ectopic liver tissue following partial removal of the lung.

Autografts of liver were implanted into the left lung (Xenopus laevis). Subsequent removal of the right lung stimulated increased mitotic activity in the lung and in the liver graft.     

Chronic hydrogen peroxide intake and peroxide metabolizing enzyme activities in some tissues of mice and rats

Summary Chronic daily intake of 0.5% H₂O₂ in drinking water decreased Se-dependent glutathione peroxidase (Se-GSHPx) activity in rat skeletal muscle, kidney and liver. Non-Se GSHPx activity decreased in kidney. Deprivation of drinking water decreased Se-GSHPx activity in kidney and non-Se GSHPx activity in kidney and liver. H₂O₂ intake decreased activity of catalase in rat skeletal muscle. H₂O₂ intake or water deprivation caused no changes in these enzyme activities in mice.     

Stimulation of cell division in ectopic liver tissue following partial removal of the lung

Summary Autografts of liver were implanted into the left lung (Xenopus laevis). Subsequent removal of the right lung stimulated increased mitotic activity in the lung and in the liver graft.We thank the Cancer Research Campaign (North of England Council) for financial assistance.     

Flavonoids as inhibitors of rat liver cytosolic glutathione S-transferase

Summary The inhibitory potencies of different flavonoids for rat liver cytosolic glutathione S-transferase activity varied over 30-fold, depending on the pattern of hydroxylation, the presence of a C-2, C-3 double bond and the substitution of a hydroxyl group with a sugar moiety. Kinetic inactivation studies of the enzyme with the inhibitor quercetin revealed a non-competitive profile versus both glutathione and 1-chloro-2,4-dinitrobenzene.     

The effects of vitamin A nutritional status on glutathione levels and microsomal lipid peroxidation in rat lung

In vitamin A-deficient rats, the glutathione level in lung was diminished and microsomal lipid peroxidation much increased. In vitamin A-loaded animals, however, both were depressed below control. Thus vitamin A protection against lipid peroxidation is independent of glutathione.     

Mitochondrial respiratory function and antioxidant capacity in normal and cirrhotic livers following partial hepatectomy

For many liver malignancies, major hepatectomy is the usual therapy. Although a normal liver has a tremendous capacity for regeneration, liver hepatectomy in humans is usually carried out on a diseased liver and, in such cases, liver regeneration takes place in a cirrhotic remnant. Mitochondrial function in cirrhotic livers shows a variety of changes compared to control livers. This study investigated how mitochondrial respiratory function and antioxidant capacity change following partial hepatectomy of cirrhotic livers, because liver regeneration requires greater energy demands and control of oxidative stress. Cirrhosis was induced in male Wistar-Furth rats by administration of thioacetamide. NADH-cytochrome c reductase activity, mitochondrial glutathione peroxidase activity and mitochondrial GSH levels were all significantly lowered in cirrhotic livers and in the cirrhotic remnants up to 72 h after 70% hepatectomy when compared to the corresponding controls. Lower respiratory control ratios with succinate as substrate were also observed from 6 to 48 h post-hepatectomy. At 24 h post-hepatectomy, higher levels of lipid peroxidation were observed. We conclude that, compared to the controls, cirrhotic livers have diminished oxidative phosphorylation capabilities due to changes in NADH and FADH₂-linked respiration as well as impaired antioxidant defenses following partial hepatectomy. Both of these factors, if critical, could then impede liver regeneration.Received 15 September 2003; received after revision 26 October 2003; accepted 19 November 2003     

Effects of chronic caffeine feeding on the activities of oxygen free radical defense enzymes in the growing rat heart and liver

The purpose of the present study was to determine the relationship between concentration of Zn, Cu and Fe, and the catalase, glutathione peroxidase and superoxide dismutase activities in the heart and liver of newborn rats whose dams were fed a diet supplemented with caffeine. Heart Zn levels of the 22- and 30-day-old rats of the caffeine group showed a decrease, whereas liver Zn levels showed an increase compared to the control. Cu levels in the liver at day 22 in the caffeine group were less than in the control. Cu- and Zn-containing superoxide dismutase activities showed an increase in the hearts of the caffeine group compared to the control. The activity of catalase and glutathion peroxidase showed no difference in the heart and liver between the groups. The present study suggests the possible involvement of superoxide dismutase enzyme in the impairment of heart formation as a result of chronic caffeine intake in the early growing period.     

The effects of vitamin A nutritional status on microsomal lipid peroxidation and α-tocopherol level in rat liver

Summary In vitamin A-deficient rats, liver glutathione peroxidase activity was decreased, -tocopherol content was strongly enhanced, but microsomal liquid peroxidation remained unchanged.     

Effect of acute and chronic ethanol ingestion on the content of reduced glutathione of various tissues of the rat

Summary The effect of acute ethanol ingestion (5 g/kg) by fasted rats, or chronic treatment in fed animals, revealed a significant decrease in the content of reduced glutathione of the liver and kidney. No changes were observed in reduced glutathione levels of the pancreas, intestines, stomach or spleen in the acute model. In this condition, the time course study of the decrease in reduced glutathione levels showed a progressive effect in the liver and a rapid and constant effect in the kidney.These studies were supported by the Grant M 308-792 from the Servicio de Desarrollo Cientifico, Artistico y de Cooperacion Internacional, Universidad de Chile, and by the Research Associateship Program (L.A.V.) from the Natural Sciences and Engineering Research Council of Canada.     

The effects of vitamin A nutritional status on glutathione levels and microsomal lipid peroxidation in rat lung

Summary In vitamin A-deficient rats, the glutathione level in lung was diminished and microsomal lipid peroxidation much increased. In vitamin A-loaded animals, however, both were depressed below control. Thus vitamin A protection against lipid peroxidation is independent of glutathione.Acknowledgments. We thank Dr L. Y. Y. Fong and Mr David Y. H. Woo for preparing the animals used in this research, for retinol determinations and for valuable discussions, and also the China Medical Board of New York and the University of Hong Kong for the award of a Fellowship to V.P.     

Differential influences of various arsenic compounds on glutathione redox status and antioxidative enzymes in porcine endothelial cells

The cellular response and detoxification mechanisms in porcine endothelial cells (PAECs) to arsenic trioxide (As2O3), sodium arsenite (NaAsO2) and sodium arsenate (Na2HAsO4) were investigated. NaAsO2 at 20 microM for 72 h increased Cu/Zn superoxide dismutase activity resulting in elevated intracellular hydrogen peroxide levels, but As2O3 and Na2HAsO4 did not. Trivalent arsenic compounds increased intracellular oxidized glutathione (GSSG) and total glutathione (GSH) and cellular glutathione peroxidase (cGPX) and glutathione S-transferase (GST) activity, but not glutathione reductase activity. The increased cGPX activity resulted in an elevated cellular GSSG content. Na2HAsO4 increased the cellular GSSG level at 72 h compared to controls. These results imply that the increased GSH content responding to the oxidative stress by trivalent arsenic compounds may be mainly related to the regulation of GSH turnover. The increased GST activity implies that the elevated intracellular GSH level responding to the oxidative stress may be used to conjugate arsenic in PAECs and facilitate arsenic efflux.     

Early effects of copper accumulation on methionine metabolism

Wilson's disease is characterized by longterm hepatic accumulation of copper leading to liver disease with reduction of S-adenosylmethionine synthesis. However, the initial changes in this pathway remain unknown and constitute the objective of the present study. Using the Long Evans Cinnamon rat model, early alterations were detected in the mRNA and protein levels, as well as in the activities of several enzymes of the methionine cycle. Notably, the main change was a redox-mediated 80% decrease in the mRNA levels of the methionine adenosyltransferase regulatory subunit as compared to the control group. Moreover, changes in S-adenosylmethionine, S-adenosylhomocysteine, methionine and glutathione levels were also observed. In addition, in vitro experiments show that copper affects the activity and folding of methionine adenosyltransferase catalytic subunits. Taken together, these observations indicate that early copper accumulation alters methionine metabolism with a pattern distinct from that described previously for other liver diseases.     

The effects of vitamin A nutritional status on glutathione, glutathione transferase and glutathione peroxidase activities in rat intestine

In rat intestine, the glutathione level was increased, glutathione peroxidase activity decreased and glutathione-S-transferase unchanged by vitamin A deficiency.     

The effects of vitamin A nutritional status on glutathione,glutathione transferase and glutathione peroxidase activities in rat intestine

Summary In rat intestine, the glutathione level was increased, glutathione peroxidase activity decreased and glutathione-S-transferase unchanged by vitamin A deficiency.     

Endurance training and antioxidants of lung

Mice and rats were adjusted to daily treadmill training programs, which were heavy enough to increase the oxidative capacity of skeletal muscles. Endurance training did not affect the activities of catalase and glutathione peroxidase and the concentration of vitamin E in the lungs of mice and rats. Thus increased ventilation and oxygen utilization induced by exercise training do not modify lung antioxidants, in contrast to hyperoxia and hypoxia.     

Glutathione peroxidase in erythrocytes and plasma of rats during pregnancy and lactation

Summary The glutathione peroxidase activity in the plasma of rats on the 20th day of pregnancy was found to be 50% lower than in nulliparous control animals. During lactation, the level rose again but was still significantly different from that of the control rats on the 20th day post partum. The erythrocyte enzyme activity remained unchanged.Acknowledgments. We should like to thank Dr A. Wendel, Physiologisches Institut der Universität Tübingen, for his advice on carrying out the glutathione peroxidase assay.     

Effect of the rat liver S9 fraction on the mutagenicity of azathioprine in the Salmonella/mammalian microsome assay

Azathioprine is a direct acting mutagen in Salmonella typhimurium TA100 and TA1535. Addition of rat liver S9 fraction with or without co-factors, or glutathione, causes a decrease in the mutagenicity of azathioprine in TA100 and an increase in TA1535, indicating the effect of SH groups.