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.     

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.     

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.     

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.     

Differential effect of silybin on the Fe2+-ADP and t-butyl hydroperoxide-induced microsomal lipid peroxidation

Summary We have observed a differential effect of silybin dihemisuccinate on rat liver microsonal oxygen consumption and on lipid peroxidation induced by NADPH-Fe²⁺-ADP and t-butyl hydroperoxide. These results are ascribed to the antioxidant properties of the flavonoid. The differences observed in the effect of the catalysts may be a consequence of the different capacity of silybin to act as a scavenger of free radicals formed by NADPH-Fe²⁺-ADP or t-butyl hydroperoxide.This research was supported in part by grant B-2019-8412 from Dirección de Investigación y Bibliotecas, Universidad de Chile.     

Plasma and hepatic antioxidant control and vitamin A nutritional status

Twenty-seven rats were divided into three groups and fed on diets containing 0.3, 6 or 60 RE (retinol equivalent) retinyl palmitate/g food. After 7 weeks, hepatic vitamin A uptake was found to be more efficient in vitamin A-deficient rats than in rats given adequate vitamin A. We showed that during the metabolic adaptation of the animals to the level of vitamin A in the diet, extensive modifications occur in the antioxidant defences of the organism. In parallel with the increase in the level of vitamin A, the decrease in the level of -tocopherol in the plasma can bring about a greater susceptibility of the lipoproteins to oxidative stress. Similarly, the decrease in the hepatic -tocopherol level and in glutathione peroxidase activity leads to the weakening of the liver's antioxidant defences.     

Inhibitory effects of phenolic compounds on CCl4-induced microsomal lipid peroxidation

Summary The antiperoxidative effects of 35 phenolic compounds, most of them belonging to the flavonoid class, were investigated using CCl₄-induced peroxidation of rat liver microsomes. This system was rather insensitive to gallic acid, methyl gallate and ellagic acid. Nevertheless it was inhibited by flavonoids and structure/activity relationships were established. The most potent compounds were gardenin D, luteolin, apigenin (flavones), datiscetin, morin, galangin (flavonols), eriodictyol (flavanone), amentoflavone (biflavone) and the reference compound, (+)-catechin. The natural polymethoxyflavone gardenin D has shown a potency comparable to that of (+)-catechin and higher than that of silybin. Thus, it may be considered as a new type of natural antioxidant with potential therapeutical applications.     

Effect of chronic ethanol treatment on peroxisomal acyl-CoA oxidase activity and lipid peroxidation in rat liver and heart

Summary Chronic ethanol administration was shown to increase catalase and acyl-CoA oxidase activities in rat myocardium but did not alter the activity of liver peroxisomal enzymes. As a result of alcohol consumption a 2–3-fold increase in the level of lipid peroxidation was observed in the heart tissue while in the liver the induction was much less pronounced.     

Effect of vitamin A deficiency on the levels of glutathione and glutathione-S-transferase activity in rat lung and liver

Summary Vitamin A deficiency reduces the content of glutathione in liver and lung. Also, glutathione S-transferase activity is decreased significantly in the lung, whereas its activity is increased in the liver.     

Role of lipid peroxidation in ferric lactate-enhanced calcium uptake by Ehrlich carcinoma cells

Comparison of Ca²⁺ uptake by Ehrlich carcinoma cells in presence of ferric lactate or aluminum lactate, and formation of thiobarbituric acid-reactive substances, suggests that lipid peroxidation is associated with but not the cause of calcium overload that can lead to cell injury and death.     

Age-related lipid peroxidation in the digestive gland of mussels: The role of the antioxidant defence systems

Summary The main cellular defence systems against free radical-mediated oxidative stress are significantly reduced in the dige⁺ive gland of aged (>10 years old) compared to younger (2–4 years old) mussels (Mytilus edulis L.). Moreover, the concentration of lipid peroxidation products (malondialdehyde) is increased in the same age group with respect to younger animals. The obtained data indicate that an impairment of the antioxidant defence systems would render the older animals more susceptible to peroxidative stress, thus supporting the general significance of the free radical theory of aging.     

In vivo effects of immunostimulating lipopeptides on mouse liver microsomal cytochromes P-450 and on paracetamol-induced toxicity

Summary Immunomodulating lipopeptides lauroyl-L-Ala--D-Glu-LL-A2pmNH2-Gly (RP 44.102) and lauroyl-L-Ala--D-Glu-LL-A2pmNH2 (RP 56.142) were found to protect mice against the hepatotoxicity of paracetamol, which is due to cytochrome P-450 dependent formation of toxic metabolites and radicals. In fact they decreased the amount of hepatic microsomal cytochrome P-450, and the level of CCl₄-induced lipid peroxidation. In contrast lauroyl-L-Ala--D-Glu-DD-A2pmNH2 (RP 53.204), which only differs by the configuration of the two chiral carbons of A2pm (diaminopimelic acid) and is not an immunomodulating agent, failed to protect against poisoning by paracetamol and had no effect on the level of hepatic cytochrome P-450 or the microsomal CCl₄-induced lipid peroxidation. This provides a clear connection between the immunostimulating properties of a compound and its effects on xenobiotic biotransformations.     

Lipid peroxidation,low-level chemiluminescence and regulation of secretion in the mammary gland

In mammary explants of lactating mice, changes in the intensity of chemiluminescence (CL) were observed after the addition to the incubation medium of hormones and mediators that are involved in the regulation of secretion: oxytocin, acetylcholine, epinephrine and norepinephrine. A 15-min period of treatment with oxytocin, epinephrine or norepinephrine changed the level of thiobarbituric acid-reactive substances (TBARS). Two mammary explants, one of which was treated with oxytocin, acetylcholine, epinephrine or norepinephrine, were found to interact even when separated by a quartz glass wall. Analysis of the level of TBARS formation in these two explants showed that the observed interactions might be connected with light emission resulting from lipid peroxidation (LP) processes. The possible role of LP and low-level CL in the regulation of mammary gland secretion is discussed.     

The effects of vitamin E-deficiency on serum prolactin and serum luteinising hormone levels in the pregnant rat

Summary No significant differences were observed between the serum prolactin or serum LH levels of vitamin E-deficient or vitamin E-replete rats during the first 12 days of gestation. It is suggested that pituitary dysfunction is not the cause of the characteristic foetal resorption observed in vitamin E-deficient rats.Acknowledgments. The authors would like to thank Dr A.F. Parlow of the NIAMDD Rat Pituitary Hormone Distribution Programme for the generous supply of kits for the measurement of rat prolactin and LH, and Dr K.M.L. Morris (City of London Polytechnic) for arranging facilities for the radioiodination of the purified hormones used in the radioimmunoassays.     

Acute60Co-gamma irradiation of rats decreases the inhibitory effect of succinate on the lipid peroxidation of liver mitochondria

Summary Succinate inhibits NADPH-dependent lipid peroxidation of liver mitochondria. This effect of succinate decreased 12 h after whole-body⁶⁰Co-gamma irradiation, depending on the dose of irradiation.     

Effect of various stressors on the levels of lipid peroxide,antioxidants and Na+, K+-ATPase actrivity in rat brain

The level of malondialdehyde (MDA), an index of lipid peroxidation, and the antioxidants superoxide dismutase (SOD) and glutathione (GSH), as well as the activity of Na⁺, K⁺-ATPase, were assessed in whole rat brain after immobilization, anemic hypoxia (NaNO₂) and 72 h starvation. The effect of these stressors on plasma glucose and corticosterone levels was also observed. Hypoxia and starvation stimulated the lipidj peroxide formation in braini as indicated by an increase in the level of MDA, being higher after starvation than hypoxia. Brain SOD activity was also increased in response to hypoxia and starvation while GSH content was only diminished ini hypoxia. However, neither MDA nor antioxidants were affected by immobilization. On the other hand, the activity of brain Na⁺, K⁺-ATPase was significantly increased by immobilization and hypoxia but decreased in starvation. A similar pattern of change was also observed in plasma glucose and corticosterone levels in response to these stressors. These results elucidate differences in the biochemical response of animals towards various types of stress, with increased lipid peroxide formation in hypoxia and starvation.     

Effect of chronic ethanol treatment on peroxisomal acyl-CoA oxidase activity and lipid peroxidation in rat liver and heart

Chronic ethanol administration was shown to increase catalase and acyl-CoA oxidase activities in rat myocardium but did not alter the activity of liver peroxisomal enzymes. As a result of alcohol consumption a 2-3-fold increase in the level of lipid peroxidation was observed in the heart tissue while in the liver the induction was much less pronounced.     

Effect of diurnal rhythm and food withdrawal on serum lipid levels in the rat

Résumé Chez le rat albinos, le niveau des triglycérides sériques varie au cours de la journée, avec un maximum à 08.00 h et un minimum au début de la soirée. Cette variation est plus marquée chez les rats à jeun. Par contre, aucune variation n'a été observée dans les niveaux de cholestérol et de phospholipides.     

The effects of beta-endorphin on arginine-8-vasopressin and oxytocin levels in rat brain areas

Summary Measurements were made of the effects of intracerebroventricular treatment with beta-endorphin (BE; 100 ng) on the arginine-8-vasopressin (AVP) and oxytocin contents of rat hypothalamic and limbic brain areas (hippocampus, amygdala and septum). The hormone concentrations were determined by radioimmunoassay. The administration of BE resulted in a significant reduction of the AVP level in the amygdala in a naloxone-reversible manner. Naloxone (Nal) administered subcutaneously significantly increased the AVP content in the septum. The results revealed that BE and Nal had regionally specific effects on the activity of the vasopressinergic system but not on that of the oxytocinergic system in the brain.