Vitamin E-supplemented Diet Research Articles

Effect of dietary vitamin E on nitrite-treated rats

The effect of dietary vitamin E on cellular responses to nitrite was studied in rats. One-month-old male Sprague-Dawley rats were fed a basal vitamin E-deficient diet with or without 100 ppm vitamin E and 1000 ppm sodium nitrite (NaNO 2) for 9 weeks. In addition to a high mortality rate, nitrite-fed rats maintained on a vitamin E-deficient diet exhibited a marked increase in liver necrosis, tubular nephrosis and myodegeneration, as well as greater biochemical and hematological alterations when compared to the control animals. No animal mortality or histopathologic lesions in any tissues were observed in rats receiving a vitamin E-supplemented diet with or without nitrite. The results suggest that depletion of vitamin E renders rats more susceptible to the adverse effect of nitrite, and that nitrite administration potentiates deficiency of vitamin E in rats.

Effect of Dietary Level of Vitamin E on the Immune System of the Spontaneously Hypertensive (SHR) and Normotensive Wistar Kyoto (WKY) Rat

Spontaneously hypertensive rats (SHR) had depressed splenic mitogen responses as well as lower splenic vitamin E when compared to normotensive Wistar Kyoto strain (WKY) rats fed a stock diet. Both strains had depressed T- and B-cell splenic mitogen responses after 17 weeks on a semipurified, vitamin E-deficient diet when compared to animals fed either stock or dl-α-tocopheryl acetate-supplemented semipurified diet. In addition, SHR fed the vitamin E-supplemented diet had enhanced thymocyte rosetting compared to those fed the vitamin E-deficient diet. In contrast, the dietary vitamin E level did not affect the thymocyte rosetting in WKY rats.

Effect of vitamin E on adjuvant arthritis in rats

Adjuvant arthritis was induced in rats fed a diet deficient in or supplemented with vitamin E, and its severity was scored according to the macroscopic findings of their legs, tails, and ears. The average score so obtained was higher in the vitamin E-deficient diet group than in the group of rats supplemented with vitamin E. Whereas the A G ratio remained depressed in vitamin E-deficient rats, rats on a vitamin E-supplemented diet showed a fast recovery from A G -ratio depression. The serum levels of β-glucuronidase and acid phosphatase were elevated after administration of an adjuvant. The serum levels of these lysosomal enzymes showed a remarkable increase in rats fed a vitamin E-deficient diet, while the elevation in lysosomal enzyme levels in rats fed a vitamin E-supplemented diet was inhibited. The levels of thiobarbituric acid (TBA) reactants in the synovia were elevated at 2 weeks after exposure to the adjuvant and were decreased thereafter. In rats maintained on a diet supplemented with vitamin E, on the other hand, the increase in synovial level of TBA reactive substances was inhibited. These observations suggest that the aggravation of adjuvant arthritis may be associated with lipid peroxidation and that antioxidants, such as vitamin E, may be beneficial for arthritis.

Metabolic disorders of serum lipoproteins in endotoxin-poisoned mice: the role of high density lipoprotein (HDL) and triglyceride-rich lipoproteins.

A study was performed to clarify the role of serum lipoproteins, especially high density lipoprotein (HDL) and triglyceride-rich lipoproteins in endotoxemic or endotoxin-poisoned animals. The level of HDL-cholesterol decreased markedly in mouse serum 18-24 hr postintoxication, while the amount of low density lipoprotein (LDL)-cholesterol in the sera of poisoned mice was about 175% of that of the controls. Serum lecithin-cholesterol acyltransferase activity in the poisoned mice decreased slightly for 3-6 hr after endotoxin injection, but became markedly increased at 18-24 hr as compared with that in the controls. The amount of serum very low density lipoprotein (VLDL) showed a marked increase in the poisoned mice 8-24 hr postintoxication. The HDL fraction in the electrophoretic patterns of serum was reduced according to the dose of endotoxin 18 hr postintoxication. The HDL fraction in mice injected with lead acetate plus endotoxin was markedly lower than that in the poisoned mice. When streptozotocin-diabetic mice were injected with endotoxin, the HDL fraction was higher than that in the endotoxin-poisoned mice. In endotoxin-poisoned mice a correlation was observed between the lipid peroxide and LDL levels in the serum. In disk electrophoretic patterns, the HDL fraction in mice given vitamin E-supplemented diet showed a higher level than that in mice given a normal diet. Lipoprotein lipase (LPL) activity in poisoned mice significantly decreased to 59% of the control value 18 hr postintoxication, but hepatic triglyceride lipase activity was only slightly increased in endotoxin-poisoned mice. In analysis of HDL apoprotein peptide in serum lipoprotein, the apo C-II peptide level was clearly lower in mouse serum 18 hr postintoxication than that in the controls. These results suggest that the decrease in LPL activity in endotoxin-poisoned mice may be closely related to a decrease in the apo C-II peptide level, and also that it plays an important part in HDL and triglyceride-rich lipoprotein metabolism in the poisoned mice.

The effect of vitamin E on platelet kinetics of stroke-prone spontaneously hypertensive rats (SHRSP).

The platelet survival time was shortened in stroke-prone spontaneously hypertensive rats (SHRSP) at 10 weeks of age on feeding the regular diet but it was normalized on administering the vitamin E-supplemented diet. Platelet survival time was normal in stroke-resistant spontaneously hypertensive rats (SHRSR) at 10 weeks of age on feeding the regular diet but it was shortened when supplying the vitamin E-free diet. The maximal uptake of 75Se-selenomethionine by platelets was increased in SHRSP at 10 weeks of age on feeding the regular diet. It was further increased in SHRSP on feeding the vitamin E-free diet. On the other hand, the increased maximal uptake of 75Se-selenomethionine by platelets was normalized in SHRSP on feeding both the vitamin E-supplemented diet and the vitamin E-supplemented diet after administering the vitamin E-free diet. Therefore, we concluded that the deficiency of vitamin E brought about the shortening of platelet survival time and enhanced platelet production.

Effect of alpha-Tocopherol on endotoxicosis.

The effect of alpha-tocopherol in endotoxicosis was studied. The alpha-tocopherol level significantly decreased in mouse liver 18 hr after endotoxin administration, thereafter tending to increase to approach the normal range. In endotoxin-tolerant mouse liver, the lipid peroxide level was reduced to less than half of that in nontolerant animals following endotoxin challenge. The liver lipid peroxide level and serum lactate dehydrogenase or acid phosphatase leakage were studied in mice fed a vitamin E-deficient (ED) diet and a vitamin E-supplemented (ES) diet for 40 days. ED mouse liver exhibited a higher formation of lipid peroxide after endotoxin was given while there was a markedly lower level in ES mouse liver. There was significantly more serum lactate dehydrogenase or acid phosphatase leakage in ED mice than in ES mice after endotoxin administration. There was about a 25% decrease in liver superoxide dismutase (SOD) activity in endotoxin-poisoned mice fed both the normal and the ED diets, while the activity was at a higher level in ES-fed mice. These results suggest that alpha-tocopherol may be helpful in preventing membrane instability in endotoxin poisoning.

Production of volatile hydrocarbons by isolated hepatocytes: An in vitro model for lipid peroxidation studies

Increased production of pentane, ethane, ethylene, and thiobarbituric acidreactive substances were measured in hepatocytes treated with bromotrichloromethane (CCl 3Br), carbon tetrachloride, and chloroform. Linear correlations between these indices of lipid peroxidation were found when CCl 3Br-treated hepatocytes still had high viability. Of the halogenated hydrocarbons tested, CCl 3Br was the most potent initiator of peroxidation and caused the greatest amount of cellular damage as measured by trypan blue dye exclusion and glutamate pyruvate transaminase released from the cells. Hepatocytes from livers of rats fed a semisynthetic vitamin E-supplemented diet were slightly more protected from peroxidation and cellular damage induced by CCl 3Br treatment than were hepatocytes from rats fed a vitamin E-deficient diet. The usefulness of isolated hepatocytes as a model for lipid peroxidation was demonstrated.

Generation of prostacyclin-like substance and lipid peroxidation in vitamin E-deficient rats

Endogenous generation of prostacyclin (PGI 2)-like substance and lipid peroxidation were studied in the aorta of rats fed on vitamin E-deficient diet and/or vitamin E-supplemented one for 4 to 10 months after they were weaned at 4 weeks. PGI 2-like substance was produced by the incubation of the aortic ring in pH 9.0 borate-buffered saline and was estimated by comparison of its antiaggregatory activity with that produced by known amounts of synthetic PGI 2. Thiobarbituric acid-reacting substance (TBARS) was determined as an indicator of lipid peroxidation. The generation of PGI 2-like substance was significantly reduced in rats fed on vitamin E-deficient diet for 8 and 10 months as compared with that in the animals fed on vitamin E-supplemented one for the same period (p<0.001). Mean concentration of TBARS in the aortae of rats fed on vitamin E-deficient diet for 10 months was significantly higher than that of the animals fed on vitamin E-supplemented diet for the same feeding period (p<0.001). These alterations in the aortae of rats fed on vitamin E-deficient diet were corrected by feeding them on vitamin E-supplemented diet for subsequent 2 months.

Effects of long-term ozone exposure and dietary vitamin E in rats.

Rats fed on a vitamin E-deficient diet (E-depleted group) and a vitamin E-supplemented diet (E-supplemented group) were exposed to 0.3 ppm ozone for three hours daily, five days a week for seven months. Then animals from each group were sacrificed, and electron microscopic studies on the lung and biochemical examinations on the lung and liver were performed. 1) Vitamin E concentration in serum decreased following ozone exposure in the E-supplemented group, whereas it remained unaffected the E-depleted group. 2) Both TAB value and % release of lysosomal enzyme (acid phosphatase) of the liver were increased in vitamin E-depleted air-exposed rats, and showed even higher values following ozone exposure. Levels of both components were highest in the vitamin E-depleted ozone-exposed rats, thus demonstrating that there are a marked increase in lipid peroxide and the increased labilization of lysosomes in this instance. 3) Arachidonic acid (20:4) of total lipid, phospholipid and lecithin in the lung tissue showed a tendency to decrease in vitamin E-depleted air-exposed rats. Those in the ozone-exposed animals showed in both groups a tendency to increase in total lipid and lecithin, and to decrease in phospholipid. However, a change in the fatty acid composition following ozone exposure was generally mild. 4) The fatty acid composition of phospholipid in lung washings did not show a remarkable change following ozone exposure in either group, thus suggesting that it has the resistivity to oxidation. 5) Morphological observations on the lung with the scanning and transmission electron microscopes did not reveal any clear differences between the two groups. The defensive effect of vitamin E on ozone toxicity induced by long-term exposure to ozone was not made clear by the morphological or biochemical examination of the lung. However, biochemical findings in liver of rats exposed to ozone suggested the possibility that vitamin E deficiency permits the damaging effects of lipid peroxidation on biological membranes.

Effects of lipid peroxides and vitamin E on the generation of prostacyclin (PGI2) by rat aorta

Endogenous generation of prostacyclin (PGI2) and lipid peroxidation were studied in the aorta of rats fed on vitamin E-deficient diet and/or vitamin E-supplemented one for 4 to 10 months after they were weaned at 4 weeks. PGI2 was produced by the incubation of the aortic rings in pH 9.0 borate-buffered saline and was estimated by comparison of its anti-aggregatory activity with that produced by known amounts of synthetic PGI2. Thiobarbituric acid-reactive substance (TBARS) was determined as an indicator of lipid peroxidation. 15-Hydroperoxyarachidonic acid inhibited PGI2 generation in vitro. The generation was significantly reduced in rats fed on vitamin E-deficient diet for 8 and 10 months as compared with that in the animals fed on vitamin E-supplemented one for the same period (p<0.001). Mean concentration of TBARS in the aortae of rats fed on vitamin E-deficient diet for 10 months was significantly higher than that of the animals fed on vitamin E-supplemented diet for the same feeding period (p<0.001). These alterations in the aortae of rats fed on vitamin E-deficient diet were corrected by feeding them on vitamin E-supplemented one for subsequent 2 months.

Comparative Effects of Selenium and Vitamin E in Lead-poisoned Rats

Weanling male rats were fed a Torula yeast diet supplemented with selenium, vitamin E, or both for 3 months. Of rats fed each diet, one group received 250 ppm lead in the drinking water and another group did not. In rats not poisoned with lead, neither vitamin E nor selenium deficiency affected spleen weight, hematocrit value, or erythrocyte mechanical fragility. Vitamin E deficiency increased the splenomegaly, anemia, and mechanical fragility of red cells of lead-poisoned rats, whereas selenium deficiency did not. Addition of 0.5 ppm selenium to the vitamin E-supplemented diet increased slightly the splenomegaly and anemia in lead-poisoned rats. Excess levels of selenium (2.5 and 5 ppm) in the vitamin E-deficient diet had little or no effect on spleen size or hematocrit of rats not receiving lead, but partially prevented the splenomegaly and anemia of red cells from either non-poisoned or lead-oisoned vitamin E-deficient rats, but not as effectively as vitamin E. These results show that vitamin E status of rats is more important that selenium status in determining response to toxic levels of lead. Excess dietary selenium did protect partially against lead poisoning in vitamin E-deficient rats, but the levels of selenium used were toxic in themselves.

Vitamin E Decreases Erythrocyte Fragility after Whole-Body Irradiation

Subsequent to weaning, male Swiss Albino mice were administered a Vitamin E-supplemented diet or a low Vitamin E diet. After 43 days on the respective diets, half the subjects in each group were exposed to 500 rads from a 230 kVp X-ray machine at a dose rate of 25 rads/minute. Mice were sampled at various times post-irradiation. Vitamin E deficiency was confirmed by the Rose-Gyorgy hemolysis test. A test for spontaneous hemolysis was employed to assess erythrocyte fragility. Erythrocytes from subjects in the irradiated deficient group usually exhibited greater fragility. The least fragile erythrocytes were generally found to be those from subjects in the irradiated supplemented group. A statistically significant radiation effect, Vitamin E effect, and interaction term were obtained.

Vitamin E, steroids, and liver microsomal hydroxylations

An enzyme system that is tightly bound to the endoplasmic reticulum of liver carries out the hydroxylations of a wide variety of substrates, which include a large number of drugs, carcinogenic hydrocarbons, as well as endogenous substrates as fatty acids and steroids. The activity of this pathway is influenced by the age, species, strain, sex, and prior treatment of the animal. Exposure of animals to insecticides, carcinogens, and drugs results in increased activity. The regulation of this liver mixed-function oxidase pathway in terms of "normal" physiological components has not been extensively studied. That androgens may have a ce:role is suggested by the observation that adult males have higher hydroxylation rates than immature animals, females, and castrated males, and that the latter activities are stimulated by testosterone. Investigations carried out in this laboratory have suggested that α-tocopherol has a ce:role in regulating the activity of this microsomal hydroxylating system. The specific activities for drug hydroxylations are depressed in microsomes from livers of rats and rabbits that have been fed a vitamin E-deficient diet. Addition of antioxidants or α-tocopherol to the incubation systems does not restore the activity. Within 12 hr of the treatment of the animals with α-tocopherol, normal activity is restored. This effect is prevented if the animals are pretreated with actinomycin D. Treatment of the animals with DPPD did not reverse the effect of vitamin E-deficiency. Both androgens and α-tocopherol are endogenous compounds that appear to regulate the activity of liver mixed-function oxidases. Phenobarbital has been reported to induce liver hydroxylations in the castrated, adrenalectomized rat only when the animals have been pretreated with androgen. The aim of the present study was to determine whether the effect of α-tocopherol on microsomal oxidases was mediated via androgens or if the effect was independent of these steroids. Drug metabolism, microsomal cytochromes, and lipid peroxidation by liver microsomes of control rats, fed a vitamin E-supplemented diet, and experimental rats, fed a vitamin E-deficient diet were compared. Identical analyses were also made of control and experimental rats that were castrated, adrenalectomized, or both castrated and adrenalectomized. Groups of rats in which steroid producing organs were surgically removed were treated with appropriate replacement steroids or α-tocopherol. To determine whether the effect of α-tocopherol on microsomal hydroxylations was similar to that of phenobarbital, induction by this drug was studied in unoperated, castrated, adrenalectomized, and castrated-adrenalectomized rats. The specific activities were not decreased in vitamin E-supplemented animals after castration, unlike those of the vitamin E-deficient rats. Adrenalectomy resulted in a diminution in both groups. In the vitamin E-deficient rat the effect of castration could be reversed with α-tocopherol or testosterone. Corticosterone plus hydrocortisone partially restored activity in adrenalectomized controls and experimentals, and in the latter group vitamin E had the same effect. Steroid hormones were partially restored in controls and experimentals that had been castrated and adrenalectomized. These effects were also seen with tocopherol treatment of the double-operated experimental. The effectiveness of phenobarbital as an inducer was found to depend in part on the androgen status of the animals but part of the effect was independent of this factor. In regard to phenobarbital induction, the vitamin E-supplemented animal was less dependent on androgen than the deficient rat and the requirement for androgen in the experimental animal was replaced by tocopherol.

A comparison of the distribution of Se75in proteins of blood,liver,and kidney from rats differing in Selenium status

Abstract Rats maintained on a diet deficient in a-tocopherol and selenium began dying after 3 weeks. The livers exhibited classical dietary necrotic degeneration. The distribution of Se75 in proteins of blood, liver, and kidney separated by gel-filtration was compared 3 days after injecting Se75labelled sodium selenite into rats differing in selenium and vitamin E status. No differences were found between the distribution patterns of Se75 in proteins from animals deficient in vitamin E and in those from animals fed a vitamin E-supplemented diet. For animals fed seleniumdeficient or selenium-supplemented diets the patterns of Se75 distribution in liver and plasma proteins differed markedly, but little difference was noted in the proteins of the kidney. After 11 weeks on the selenium-deficient diets, by which time the liver selenium concentration had fallen to 0.013 μp,g!g (wet weight), no difference was found between the in vitro uptake of Se75 into the red cells of the blood of the deficient animals and t...

Vitamin E Deficiency in the Rat: II. THE EFFECT OF RAT LIVER MICROSOMES AND CYTOPLASMIC SUPERNATANT ON RESPIRATORY DECLINE

Abstract Weanling male rats were fed for approximately 3 weeks either a vitamin E-deficient or a vitamin E-supplemented diet. Liver homogenates were prepared and separated into mitochondrial, microsomal, and supernatant fractions, and the contributions of the microsomal and supernatant fractions to the maintenance or inhibition of mitochondrial oxidation of β-hydroxybutyrate were studied. When microsomes were added to mitochondria such that approximately equal amounts of protein from each fraction were present, oxidation was inhibited in a manner similar to that of vitamin E-deficient homogenates, regardless of whether the mitochondria or microsomes were derived from either vitamin E-deficient or vitamin E-supplemented rats. The further addition of the supernatant fraction from either type of liver resulted in maintenance of oxygen consumption when vitamin E-supplemented microsomes were present. The microsomal inhibitor was inactivated by boiling, but remained bound to the microsomal membranes after both sonic disruption followed by dialysis and sonic disruption followed by centrifugation. Dialysis of the supernatant fraction removed the factor, or factors, which overcame the inhibition due to the vitamin E-supplemented microsomes. Inhibition of oxygen consumption was not correlated with either peroxidation or lysosomal enzyme activity. It is suggested that the microsomal inhibitor is protein in nature.

Vitamin E deficiency in the rat: I. Effect of substrate concentration on respiratory decline in liver homogenates from rats fed a vitamin E-deficient diet

Male Holtzman rats were maintained for approximately 3 weeks on either a vitamin E-deficient or vitamin E-supplemented diet. The capacity of liver homogenates from these animals to oxidize succinate, α-ketoglutarate, β-hydroxybutyrate, pyruvate, malate, and DPNH was measured over extended periods of time, and in the presence of different substrate concentrations. The decline in rate of oxidation, with time of incubation, differed, depending on the substrate employed, the concentration of substrate, and whether vitamin E was present or absent in the diet of the donor animal. The concentration of α-ketoglutarate, β-hydroxybutyrate, pyruvate, and malate influenced the respiratory decline of vitamin E-deficient homogenates differently from the manner in which it affected the decline of supplemented homogenates. There was no apparent differences in respiratory decline between deficient and supplemented homogenates due to differences in succinate or DPNH concentration at any given substrate concentration studied.

The effect of α-tocopherol on essential fatty acid oxidation in liver mitochondria from vitamin E-deficient chicks

Development of encephalomalacia in chicks seemed related to the depression of enzymic activity in the liver mitochondria. If injected intramuscularly at the first sign of symptoms, α-tocopherol alleviated the symptoms and restored enzyme activity. Furthermore, the liver mitochondria obtained from chicks which had received injections of α-tocopherol was not subject to peroxidation to any greater degree than the liver mitochondria obtained from chicks which had been kept on a vitamin E-supplemented diet. Lipid peroxidation was found to coincide with linoleate oxidation in the liver mitochondria of vitamin E-deficient chicks. The lipoperoxides seemed to inhibit coupling of an enzyme with cytochrome c and cytochrome a in the electron-transport system.