Increase in superoxide dismutase activity concomitant with a decrease in lipid peroxidation of liver during post partum development

Disparate patterns of age-related changes in lipid peroxidation in long-lived naked mole-rats and shorter-lived mice

A key tenet of the oxidative stress theory of aging is that levels of accrued oxidative damage increase with age. Differences in damage generation and accumulation therefore may underlie the natural variation in species longevity. We compared age-related profiles of whole-organism lipid peroxidation (urinary isoprostanes) and liver lipid damage (malondialdehyde) in long living naked mole-rats [maximum lifespan (MLS) > 28.3 years] and shorter-living CB6F1 hybrid mice (MLS approximately 3.5 years). In addition, we compared age-associated changes in liver non-heme iron to assess how intracellular conditions, which may modulate oxidative processes, are affected by aging. Surprisingly, even at a young age, concentrations of both markers of lipid peroxidation, as well as of iron, were at least twofold (P < 0.005) greater in naked mole tats than in mice. This refutes the hypothesis that prolonged naked mole-rat longevity is due to superior protection against oxidative stress. The age-related profiles of all three parameters were distinctly species specific. Rates of lipid damage generation in mice were maintained throughout adulthood, while accrued damage in old animals was twice that of young mice. In naked mole-rats, urinary isoprostane excretion declined by half with age (P < 0.001), despite increases in tissue iron (P < 0.05). Contrary to the predictions of the oxidative stress theory, lipid damage levels did not change with age in mole-rats. These data suggest that the patterns of age-related changes in levels of markers of oxidative stress are species specific, and that the pronounced longevity of naked mole-rats is independent of oxidative stress parameters.

Inhibition of tumour growth and inflammation by consumption of tea

The antitumour effect of tea was evaluated in the 3-methylcholanthrene (3-MC) induced solid tumour model in mice. Both black and green tea inhibited tumour growth and prevented metastasis. Histopathological study showed that tea treatment was able to reduce malignancy. Superoxide dismutase (SOD), a free radical scavenger, was found to be significantly increased in the serum of mice administered tea. Moreover, tea extracts were able to reduce the level of thiobarbituric acid reactive substance (TBARS) in the sera of mice. Tea extracts (both black and green) also showed antiinflammatory activity in the carrageenan-induced paw oedema model in the rat.

Age-related changes in the urinary excretion of aldehydes in ad libitum fed and food-restricted rats

Age-related changes in the urinary excretion of aldehydes arising from lipid peroxidation have been investigated in male Sprague-Dawley rats aged 2, 4, 6, 12, 18, 24 and 27 months, fed ad libitum or subjected to two different regimens of calorie restriction (namely every-other-day ad libitum feeding--EOD--and 40% calorie restriction--40%DR). For only some age groups, results were compared with those obtained in ad libitum fed male Fisher 344 and Lewis rats. Results show that the urinary excretion of malondialdehyde (MDA) and formaldehyde (FA) significantly decreases, whereas that of propionaldehyde (PROP) progressively increases with age, and that urinary excretion of acetaldehyde (ACT) does not show any significant age-related variations. Dietary restriction significantly increases the urinary levels of MDA, FA and PROP without affecting their age-related modifications, and does not affect ACT urinary excretion. In conclusion, results indicate that the quantitative pattern of aldehyde production and urinary excretion may be altered by the process of aging.

Oxidative stress and gene regulation

Reactive oxygen species are produced by all aerobic cells and are widely believed to play a pivotal role in aging as well as a number of degenerative diseases. The consequences of the generation of oxidants in cells does not appear to be limited to promotion of deleterious effects. Alterations in oxidative metabolism have long been known to occur during differentiation and development. Experimental perturbations in cellular redox state have been shown to exert a strong impact on these processes. The discovery of specific genes and pathways affected by oxidants led to the hypothesis that reactive oxygen species serve as subcellular messengers in gene regulatory and signal transduction pathways. Additionally, antioxidants can activate numerous genes and pathways. The burgeoning growth in the number of pathways shown to be dependent on oxidation or antioxidation has accelerated during the last decade. In the discussion presented here, we provide a tabular summary of many of the redox effects on gene expression and signaling pathways that are currently known to exist.

Oxidative stress and superoxide dismutase in development, aging and gene regulation

Free radicals and other reactive oxygen species are produced in the metabolic pathways of aerobic cells and affect a number of biological processes. Oxidation reactions have been postulated to play a role in aging, a number of degenerative diseases, differentiation and development as well as serving as subcellular messengers in gene regulatory and signal transduction pathways. The discovery of the activity of superoxide dismutase is a seminal work in free radical biology, because it established that free radicals were generated by cells and because it made removal of a specific free radical substance possible for the first time, which greatly accelerated research in this area. In this review, the role of reactive oxygen in aging, amyotrophic lateral sclerosis (a neurodegenerative disease), development, differentiation, and signal transduction are discussed. Emphasis is also given to the role of superoxide dismutases in these phenomena.

Role of glutathione metabolism and apoptosis in the regression of liver hemopoiesis

Although apoptosis has been believed to play important roles in ontogenic development of animals, the molecular mechanism that triggers the regression of liver hemopoiesis during perinatal period is not known. Apoptosis is induced by many factors, such as decrease in growth factors and increased oxygen stress. Because hepatic gamma-glutamyltransferase (GGT) changes markedly during the perinatal period of a rodent, metabolism of glutathione (GSH), a naturally occurring major antioxidant, might change significantly in and around liver cells. To know the possible involvement of apoptosis and GSH metabolism in the regression of hemopoiesis, hepatocytes and hemopoietic cells were isolated from fetal rat liver. Biochemical analysis revealed that, during the perinatal period, hepatic GGT levels transiently increased predominantly with hepatocytes, suggesting a marked change in thiol status in and around these cells. Cell culture analysis revealed that hemopoietic cells but not hepatocytes exhibited a marked apoptosis in a thiol-free medium, as judged from DNA fragmentation. The apoptosis of hemopoietic cells was inhibited by various thiols, such as L-cysteine, N-acetyl-L-cysteine (NAC), and GSH. These observations suggested that a marked change in GSH status in and around liver cells might play critical roles in triggering apoptosis of hemopoietic cells, thereby enhancing the regression of liver hemopoiesis.

Developmental changes in the peroxidation potential of rat brain homogenate and mitochondria

Lipid peroxidation, one of the most common expressions of oxidative stress, may be altered during normal physiological states including development. We have examined the changes in lipid peroxidation in rat brain, a tissue highly susceptible to oxidative damage, during this physiological state. In vivo lipid peroxidation was moderate in the foetal and neonatal period and increased during the postnatal development. Lipid peroxidation potential in brain homogenate and mitochondria, in Tris-HCl buffer or with exogenous cofactors, such as ascorbate-Fe2+, NADPH ADP-Fe3+ and cumene hydroperoxide, showed significant changes during pre- and postnatal development. In general, brain as well as liver (used as a standard tissue for comparison) seem to have low peroxidation potential in the foetal and neonatal period which then increases at different rates during development to reach adult values at different days. The low peroxidation potential corresponds to the rapid phase of cell proliferation. These results taken together with similar earlier finding in other systems may indicate a possible occurrence of a 'permissible period' during which the low levels of lipid peroxidation may be able to yield only low amounts of cytostatic aldehydes and peroxides as byproducts, thereby allowing rapid proliferation of cells.

Multiple isoelectric variants of copper, zinc-superoxide dismutase from rat liver

Isoelectric variants of Cu,Zn-superoxide dismutase (Cu,Zn-SOD) have been reported to exist in various organs including rat liver. To elucidate the biochemical characteristics of the variants, rat liver Cu,Zn-SOD was purified and isolated into eight variants, i.e., pI 5.15, 4.88, 4.80, 4.75, 4.70, 4.65, 4.60, and 4.50. The pI 4.88 variant had the highest specific activity (4245 U/mg protein) and the highest yield (45% of original activity). The descending order of specific activity for the other variants was pI 4.80, 4.75, 5.15, 4.70, 4.65, 4.60, and 4.50. The specific activity correlated well with metal content. The specific activity for most variants was 5-9 times greater when determined at pH 10.0 than at pH 7.8. However, three preparations of pI 4.80 and 4.70 variants had 13.9-16.3 times greater specific activity at pH 10.0 versus 7.8, while one of the pI 4.60 variants was only 3.5 times greater. The rate of Coomasie brilliant blue G-250 binding was lowest with pI 4.88 followed by pIs 4.80 and 4.75. To evaluate the mechanisms which might produce these variants, the pI 4.88 variant was incubated with xanthine-xanthine oxidase or a mixture of rat liver microsome, NADPH, and sodium azide, and a shift to variants pI 4.80 and pI 4.75 was found. The shift was greatly inhibited by the presence of mannitol or by the omitting of azide, respectively. The existence of these variants was also confirmed by other methods: (i) direct application of rat liver 105,000g supernatant to an isoelectric focusing, and (ii) extraction of SOD from acetone powder prepared from rat liver homogenate. Results indicate that several variants most likely arise in tissue as a result of activated oxygen radical modification of variant pI 4.88.

Oxidative influence on development and differentiation: an overview of a free radical theory of development

Metabolic gradients exist in developing organisms and are believed to influence development. It has been postulated that the effects of these gradients on development result from differential oxygen supplies to tissues. Oxygen has been found to influence the course of development. Cells and tissues in various stages of differentiation exhibit discrete changes in their antioxidant defenses and in parameters of oxidation. Metabolically generated oxidants have been implicated as one factor that directs the initiation of certain developmental events. Also implicated as factors that modulate developmental processes are the cellular distribution of ions and the cytoskeleton both of which can be influenced by oxidants. The interaction of oxidants with ion balance and cytoskeleton is discussed.

Liposomes as membrane model for study of lipid peroxidation

This article describes the properties, production and characterization of liposomes with special reference to their use as membrane model for the study of lipid peroxidation. It presents briefly the methods that can be used for the assay of liposomal lipid peroxidation and brings out the special advantages these liposomes provide in elucidating the mechanism of lipid peroxidation by different physical and chemical agents. Studies involving liposomal lipid peroxidation by different agents and the consequent changes in the structure and function of liposomal membrane have been reviewed briefly.

Factor analysis of the activities of superoxide dismutase, catalase and glutathione peroxidase in normal tissues and neoplastic cell lines

Exploratory factor analysis of reported specific activities of the antioxidant enzymes superoxide dismutase, catalase and glutathione peroxidase in normal human tissues, normal mouse tissues, vertebrate red blood cells and neoplastic human cell lines shows that the activities of copper-zinc superoxide dismutase, catalase and glutathione peroxidase in normal tissues are influenced by a single factor. Catalase activity has the highest loading and correlation with this factor, suggesting a catalase- or hydrogen peroxide-related influence. The activity of manganese superoxide dismutase is influenced by a separate factor. The activities of copper-zinc and manganese superoxide dismutases in normal tissues therefore appear to be dichotomously regulated. The activities of superoxide dismutase and glutathione peroxidase in vertebrate red blood cells are influenced by a single factor. The activity of catalase is influenced by a separate factor. The roles of glutathione peroxidase and catalase in hydrogen peroxide catabolism in red blood cells in fact differ. In neoplastic human cell lines, two bipolar factor factors appear to influence the activities of catalase and manganese superoxide dismutase, and glutathione peroxidase and copper-zinc superoxide dismutase, respectively. The factors are, however, mainly catalase and glutathione peroxidase activity factors as the loadings and correlations of manganese superoxide dismutase on the one hand and copper-zinc superoxide dismutase on the other, with the respective factors, are relatively small. Potentially low superoxide production and intrinsically low peroxidizability of tumour cell membranes underlie the peculiar variation of antioxidant enzyme activities in tumour cells. Factor analysis is proposed as a heuristic data reduction and hypothesis-creating technique for the variation of antioxidant and other functionally-linked enzyme activities in normal and pathological cells and tissues.

Low level of lipid peroxidation in newborn rats. Possible factors for resistance in hepatic microsomes

Hepatic rough and smooth microsomes of newborn rats show less sensitivity to ascorbate- and NADPH-induced lipid peroxidation as compared to those of adult rats. Though optimum concentrations of Fe2+, ascorbate and Fe3+ significantly increase lipid peroxidation in both age groups, the lipid peroxidation observed in newborns is much less compared with that of adults. Microsomal fractions from newborn rats contain significantly lower amounts of phospholipid, NADPH cytochrome c reductase, cytochrome P-450 and a lower degree of unsaturation in lipids. These fractions also exhibit high cholesterol:phospholipid ratios. The resistance to lipid peroxidation observed in the newborns appears to be due to the low availability of substrate and high cholesterol:phospholipid ratio.

Superoxide dismutase activity in rabbit reticulocytes

Reticulocytosis was induced in rabbits by bleeding anemia and erythrocyte superoxide dismutase activity was determined. Reticulocytes were found to contain about 1.3 times as much activity as mature erythrocytes.

Some biochemical parameters of ageing in relation to dietary protein

An investigation was undertaken to study the effect of dietary protein level on some age-related biochemical processes in mice. Weanling mice were fed a laboratory diet containing protein at 6, 12 or 24% and adequate in all other nutrients, for up to 52 weeks. Although the rate of gain in body weight of the animals between 3 and 6 weeks was related to the dietary level of protein, the final body weights of mice in different groups were not significantly different. Lipid peroxidation in liver homogenate, free activities of some lysosomal enzymes of brain, liver and intestine, and the accumulation of lipofuscin pigments showed an increase with the dietary level of protein. On the other hand, the activity of superoxide dismutase in liver showed an inverse relationship to the protein level of the diet. The findings are discussed in relation to the free-radical theory of ageing.

Superoxide dismutase (EC 1.15.1.1), manganese and the effect of ethanol in adult and foetal rats

1. The activity of manganese-superoxide dismutase (EC 1.15.1.1; SOD) was increased in the livers and kidneys of adult rats after exposure to aqueous ethanol (200 ml/1) for 32 weeks. 2. The concentration of Mn in the livers and kidneys was significantly higher after 24 weeks, and by 32 weeks liver copper and zinc levels were lower. 3. The activity of foetal (day 19) liver superoxide dismutase was appreciably higher in offspring from dams receiving ethanol during pregnancy. Quantitatively the response appeared to be almost entirely due to the Mn-SOD form of the enzyme. 4. Maternal alcoholism during pregnancy had no effect on the levels of Cu, Mn or Zn in foetal (day 19) livers.

Metabolism of zinc and copper in the neonate: accumulation and function of (Zn, Cu)-metallothionein in the liver of the newborn rat

1. Measurements were made of the hepatic concentrations and contents of total and thionein-bound zinc and copper in late foetal and newborn rats and of the distribution of these metals between the particulate and soluble components of the liver. 2. The decrease in the hepatic concentration of thionein-bound Zn, which occurred with age after birth, was proportional to the increase in liver weight until the 16th day post partum; thereafter it was greater. 3. Throughout the period from birth to 25 d of age the Zn concentration remained constant in the cytosolic non-thionein fraction (i.e. total cytoplasmic Zn--thionein-bound Zn), but decreased in other compartments of the liver. 4. The same constant concentration of cytoplasmic non-thionein-bound Zn also was observed in animals with reduced total hepatic Zn contents, but normal body-weights, and in 20-d-old Zn-deficient pups. 5. The concentration of thionein-bound Cu increased significantly only between the 6th and 14th day post partum. The age-related variations in Cu contents of the particulate components closely paralleled those in the whole liver, whereas the Cu contents of the cytosolic thionein and non-thionein fractions did not increase appreciably until after the 10th day. 7. It is concluded that the cytosolic non-thionein fraction of newborn rat liver may contain particularly important metabolic sites that require Zn and a major function of Zn-thionein is to regulate the supply of the metal to these sites. As, from birth to 26 d of age, the sum of the concentrations of thionein-bound Zn and Cu was correlated with whole liver Zn, the accumulation of Cu as a soluble metallothionein seems to be a secondary event, dependent on the hepatic Zn concentration.

Radiation-induced lipid peroxidation and membrane permeability in liposomes

Effects of 60Co-gamma-ray on liposomal membranes were studied in terms of the correlation between lipid peroxidation and glucose efflux. Malondialdehyde (MDA) formation in glucose-retaining liposomes after gamma-irradiation was highly correlated with the increase in glucose efflux. The MDA formation, however, occurred only during irradiation in contrast to the glucose efflux which continued after irradiation. Both processes showed a dose threshold and a dependence on dose rate. A one-to-one relationship between glucose efflux and MDA formation was observed with radical scavengers. These results are discussed as a series of processes in membrane damage by ionizing radiation.

Superoxide dismutase (EC 1.15.1.1), zinc status and ethanol consumption in maternal and foetal rat livers

1. The activity of superoxide dismutase (EC 1.15.1.1) was not greatly affected by zinc deficiency in maternal or foetal (20 d) rat livers, although in the latter tissue it did appear to be slightly raised by Zn depletion when compared with pair-fed control animals. 2. Enzyme activity was significantly higher in livers from all foetuses after administration of aqueous ethanol at 100 or 200 ml/l to the dams during pregnancy. 3. Plasma Zn levels were significantly increased in Zn-deficient dams after ingestion of alcohol during pregnancy.

Changes in mouse liver superoxide dismutase activity and lipid peroxidation during embryonic and postpartum development

In inbred mice possessing 'high' and 'low' tissue superoxide dismutase (SOD) activity, it was observed that the difference in the SOD activities of the liver homogenates during development attains the maximum characteristic of the strain by about the 150th day. Subsequently, the SOD activity change displays a tendency in contrast with the age and the basic state. In the course of the development, a difference was also observed between the 2 mouse strains in the lipid peroxidation variation.