Endotoxin and lipid peroxidation in vitro in selenium- and vitamin E-deficient and -adequate rat tissues

The effect of Salmonella typhimurium endotoxin injected intraperitoneally into rats (0.5 mg/kg of body weight) on subsequent lipid peroxidation in vitro was assessed. Peroxidation was monitored by measuring ethane production from tissue slices, as well as thiobarbituric acid-reactive substances and conjugated dienes in tissue homogenates. Weanling rats were fed a selenium- and vitamin E-deficient basal diet or one supplemented with 0.2 mg of Se/kg of diet and 200 mg of vitamin E/kg. After 9 to 16 wk, ethane production and thiobarbituric acid-reactive substances in liver and lung generally were increased by LPS treatment of Se- and vitamin E-deficient rats. Conjugated dienes were increased by LPS treatment in liver of Se- and vitamin E-deficient rats, but paradoxically, were higher in Se- and vitamin E-adequate liver tissue. Daily injections of 1 g of hydroxyurea/kg of body weight, a cell proliferation inhibitor, for 2 d prior to LPS injection significantly decreased the LPS-induced ethane production in Se- and vitamin E-deficient rat liver and lung. These results show that low doses of LPS injected into rats stimulated lipid peroxidation in vitro in Se- and vitamin E-deficient rat liver tissue. Hydroxyurea decreased LPS-induced lipid peroxidation in vitro; this suggests that neutrophils or macrophages are involved in LPS-induced lipid peroxidation.     

Effect of an oral contraceptive on alpha-tocopherol levels in rat tissues

The distribution of alpha-tocopherol was studied in female rats receiving .052 mg/day Enovid E for 4 days, and maintained on Vitamin E deficient, adequate, or enriched (10%) diets. The administration of Enovid produced slight increases of alpha-tocopherol in the liver and ovaries of Vitamin-E-deficient animals, and decreases of alpha-tocopherol in the plasma, erythrocytes, adrenals, and kidneys of Vitamin-E-supplemented rats. The magnitude of response of different tissues varied with increasing levels of dietary tocopherol. The results support previous findings on the effects of oral contraceptives on plasma cholesterol levels and lipoprotein distribution.     

Effects of calcium ionophore on vitamin E-deficient rat muscle

Damage to skeletal muscles may be mediated via free radicals or intracellular calcium overload. To look for inter-relationships between these pathways we have examined the effect of intracellular Ca overload on muscles from rats fed on either a vitamin E-deficient or vitamin E-sufficient diet and assessed the non-enzymic lipid peroxidation in these muscles by examining the production of thiobarbituric acid reactive substances by homogenates. Vitamin E-deficient muscles were more susceptible to Ca-induced intracellular enzyme efflux and this was acutely corrected by supplementation of the external medium with 230 mumol alpha-tocopherol/l. Vitamin E-deficient muscles showed increased levels of basal lipid peroxides and were more susceptible to iron-catalysed lipid peroxidation. Addition of the Ca ionophore A23187 increased lipid peroxidation in vitamin E-deficient muscle homogenates, but had the opposite effect in vitamin E-sufficient muscles. These results demonstrate that vitamin E-deficient muscle has an increased susceptibility to intracellular Ca overload, but that this effect cannot be explained by a direct stimulatory effect of the ionophore on non-enzymic lipid peroxidation.     

Adipose tissues and vitamin E

1. Vitamin E content in the adipose tissue was examined in rats with and without vitamin E deficiency. With the progression of vitamin E depletion, the more rapid decrease in tocopherol concentration was observed in brown adipose tissue (BAT) than in white adipose tissue (WAT), and the rate of decrease of tocopherol was approximately three times faster in BAT than in WAT. After the intramuscular administration of 10 mg/kg of all-rac-tocopheryl acetate twice a week for two weeks to vitamin E-deficient rats, a similar pattern of increase was observed in the tocopherol concentrations of BAT and WAT, although the rate of increase was slower in WAT than in BAT. 2. Changes of tocopherol concentration in BAT and WAT were investigated in normo-nourished rats with hyperlipemia produced by the intramuscular injection of Triton WR-1339 for 7 days. A marked increase in tocopherol concentration was observed in both BAT and WAT in the late period of hyperlipemia, with the increase being greater in WAT. 3. The fatty acid composition of adipose tissue was compared between rats with and without vitamin E deficiency. No significant differences were observed in BAT and WAT between the two groups. 4. The glucose uptake of WAT was not altered in vitamin E-deficient rats when compared with control rats.     

Effect of vitamin E supplementation on the vitamin content of lipoprotein in young men and women

The effect of supplementary Vitamin E on the vitamin content of lipoproteins in young men and women. Inappropriate vitamin and trace element supplementation may facilitate the development of atherosclerosis. It is known that Vitamin E protects lipids from oxidative stress, while clinical signs of atherosclerosis appear later in women compared to men. AIMS: (1) The increase of vitamin E in plasma and plasma lipoproteins after 4 weeks of supplementation vitamin E was investigated, (2) furthermore it was tested whether a proportion shift occurs in alpha-tocopherol content of lipoproteins, (3) and checked for gender-related differences in plasma and plasma lipoprotein vitamin E levels before, during and after treatment, (4) plasma CRP levels as a marker of lipid peroxidation were also followed. METHODS: 5-5 young healthy men and women took part in the study, receiving 700 IU/day Vitamin E for one month. Each subject was studied before and at the end of treatment, and also one month after treatment. HDL and LDL-VLDL containing lipoproteins were separated. Vitamin E and hsCRP levels were measured (by HPLC and an immunoturbidimetric method, respectively). RESULTS: Vitamin E treatment induced in both genders an approximately threefold increase in vitamin E concentration in HDL-cholesterol (8.1 +/- 1.7 micromol/l vs. 22.5 +/- 7.5 micromol/l, p < 0.001), and a twofold increase in LDL-VLDL-cholesterol (22.0 +/- 3.7 micromol/l vs. 49.0 +/- 9.0 micromol/l, p < 0.001). Plasma and HDL vitamin E levels were higher in women than in men at the onset of treatment (6.8 +/- 0.96 micromol/l vs. 9.5 +/- 1.10 micromol/l), but during the treatment these gender-related differences disappeared. When plasma vitamin E concentration were considered 100% and the changes of the vitamin E concentrations of lipoproteins were calculated, it was found that supplementation with vitamin E in men increased the vitamin E concentration of LDL-VLDL cholesterol to a higher extent compared to women (LDL-VLDL % in men: 59.8 +/- 7.43%, in women: 49.3 +/- 7.41%, p < 0.05). All the observed changes regressed one month after cessation of supplementation. The level of hsCRP decreased during vitamin E treatment (1.07 +/- 0.9 mg/l vs. 0.2 +/- 0.14 mg/l, p < 0.001), and remained suppressed after the cessation of treatment (0.37 +/- 0.4, p < 0.01). CONCLUSIONS: These results support the hypothesis that women at young age are better protected against lipid-peroxidation as compared to men because of higher HDL vitamin E concentrations. Vitamin E supplementation in men eliminates this concentration difference between genders, and also increases LDL-VLDL vitamin E. In both genders high concentration of vitamin E in lipoproteins was associated with low hsCRP concentration.     

Effect of vitamin E on cholesterol plasma lipoprotein distribution and metabolism in rabbit

In the rabbit, after nine weeks on a basal synthetic diet supplemented with stripped corn oil and varying amount of vitamin E, plasma cholesterol level was depressed as the supplementation of vitamin E was increased. This hypocholesterolemic effect was accompanied by an increase in hepatic cholesterol-7 alpha-hydroxylase activity and cytochrome P-450 level and by a redistribution of plasma lipoprotein-cholesterol resulting in the elevation of high density to low density lipoprotein-cholesterol ratio.     

Effect of dietary cholesterol and high fat on ceramide concentration in rat tissues

OBJECTIVE: Recent studies have indicated that plasma sphingomyelin levels and sphingomyelinase activity are risk factors for atherosclerosis. Therefore, it is suggested that ceramides, which are hydrolyzed products of sphingomyelin and a biologically active lipid causing apoptosis in a variety of cells, have an important role in the incidence of atherosclerosis. In this study, we examined whether cholesterol- and fat-enriched diets, which are causes of atherosclerosis, affect ceramide metabolism. In addition, we found a relation among lipid markers of atherosclerosis such as cholesterol, triacylglycerol, and ceramide concentrations. METHODS: Male Wistar rats were fed a diet supplemented with 1% cholesterol or 30% high-fat diet for 8 wk. Tissue ceramide levels were analyzed using electrospray tandem mass spectrometry. RESULTS: The major ceramides in plasma and the liver were C24:0 and C24:1. The major ceramides in adipose tissues were C16:0 and C24:0. Therefore, the ceramide composition of the adipose tissues was different from that of plasma and the liver. In addition, total ceramide levels in plasma and the adipose tissues of rats fed cholesterol were higher than those in the control group. CONCLUSION: The accumulation of cholesterol caused an increase in ceramides, which might be a new risk factor for atherosclerosis.     

Effects of a progestogen and a sequential type oral contraceptive on plasma vitamin A, vitamin E, cholesterol and triglycerides.

Fasting blood samples were taken from 13 college students who had never been on oral contraceptives in two menstrual cycles. During the first cycle, the control cycle, each girl donated three blood samples; the first sample was given between days 1 and 5, the second sample between days 13 and 17, and the third sample between days 22 and 26 of the menstrual cycle. In the second menstrual cycle, the experimental cycle, nine girls were given Micronor, a progestogen type oral contraceptive and four girls were given Ortho-Novum SQ, a sequential type oral contraceptive. Four blood samples were obtained from each of the subjects: the first three samples were obtained in the three periods corresponding to those in the control cycle, and the fourth was taken 2 days after the subjects had stopped taking the oral contraceptive. Results showed that estrogen significantly raised plasma vitamin A and triglycerides. The progestogen, at low concentration, had little or no effect on these two lipid materials. At a higher concentration the progestogen enhanced the effect of the estrogen on plasma vitamin A and triglycerides. These effects were extended to at least 2 days after subjects had ceased taking the oral contraceptive. Plasma vitamin E levels in the subjects given Ortho-Novum SQ, were consistently but not statistically higher in the experimental cycle than in the control cycle. The correlation coefficient between vitamin E and triglycerides was statistically significant while those between the vitamin A and vitamin E and between vitamin A and triglycerides were not. Cholesterol was not affected by either Micronor or Ortho-Novum SQ.     

Effect of dietary protein on vitamin E levels in erythrocytes and tissues of rats

The effect of dietary protein level on the transfer of alpha-tocopherol in blood to tissues including RBC was studied using rats. The first experiment comprised a 10% casein (low protein), 20% casein (normal) and 20% SPI (normal soybean protein) diet groups supplemented with 71.5 mg of alpha-Toc/kg diet. In Exp. 2 the relationship of the tissue alpha-Toc level and protein level in diets, as shown by recovery from vitamin E-deficient status after the administration of alpha-Toc for 3 days, was checked by adjusting the protein level in diets to 10%, 20% and 40% casein. In Exp. 1 alpha-Toc in RBC decreased significantly in the 10% casein and 20% SPI groups compared to the 20% casein group. Moreover, alpha-Toc in kidney, lung and muscle decreased significantly in the 10% casein and 20% SPI groups. alpha-Toc in liver in the 20% SPI group decreased significantly compared to the 20% casein group. In Exp. 2 similar results were observed (Table 4), but alpha-Toc in RBC showed only a tendency to decrease with the low protein diet. In Exp. 1 free cholesterol in RBC increased significantly in the 10% casein group compared with the other two groups.     

VE、BR对糖尿病大鼠胰组织抗氧化影响

目的　探讨维生素E(VitaminE ,VE)和胆红素 (bilirubin ,BR)对糖尿病大鼠胰组织抗氧化的影响。方法　对用链佐霉素 (streptozotocin,STZ)诱发的糖尿病大鼠持续 4周给予BR、VE或BR VE后 ,测定胰组织中的丙二醛(MDA)、一氧化氮 (NO)、超氧化物歧化酶 (SOD)和一氧化氮合酶 (NOS)的水平。结果　与正常对照组比较 ,糖尿病组大鼠的MDA含量显著增加 (P <0 0 1) ,SOD活性显著降低 (P <0 0 1)。糖尿病组、给药组 (BR组、VE组和BR VE组 )大鼠的NO含量、NOS活性均显著升高 (P <0 0 1)。与糖尿病组比较 ,给药组除SOD活性显著升高 (P <0 0 1)外 ,其它 3项指标都显著降低 (P <0 0 5 ,P <0 0 1)。结论　BR和VE通过保护胰组织的SOD活性 ,降低胰组织中的MDA、NO和NOS水平 ,从而减轻自由基对糖尿病大鼠的氧化损伤。     

Effect of acute oral cadmium on mitochondrial enzymes in rat tissues

Thein vivo effects of cadmium on liver, kidney, testis, and lung mitochondrial enzymes of male rats were investigated after acute oral administration. Citrate synthase activity was significantly inhibited at all time periods studied in kidney and testis, whereas in liver the enzyme was inhibited at the end of 86 and 144 hr after cadmium administration. The succinic dehydrogenase and cytochrome C oxidase activities were significantly inhibited at all time periods in all of the four tissues.     

Effect of dietary vitamin E and selenium on DNA damage in fresh and frozen tissues

To determine whether deficiencies of dietary vitamin E and Se can elevate background DNA damage, rats were fed diets deficient in or supplemented with vitamin E (30 and 200 mg/kg diet) and Se (0.2 mg/kg diet) for 8 weeks. DNA damage was measured using the Comet (single-cell electrophoresis) assay and 8-oxodeoxyguanosine (8-oxo-dG) in liver, kidneys, and lymphocytes. We found that a deficiency of vitamin E and/or Se for 8 weeks did not significantly increase DNA damage in freshly isolated liver, kidneys, or lymphocytes. However, deficiency of vitamin E and/or Se for 8 weeks markedly increased DNA strand breaks in frozen kidney (-80 degrees C for 72 hours) and in lymphocytes incubated overnight at 37 degrees C, both of which were effectively prevented by supplementation of Se and vitamin E. However, vitamin E at 200 mg/kg did not afford more protection than it did at 30 mg/kg). Little or no significant increase in DNA damage was found in frozen livers. These results indicate that freezing or freeze-thawing of tissues may cause oxidative damage to DNA when the tissues are deficient in a major antioxidant, and that normal levels of vitamin E (30 mg/kg diet) and Se (0.2 mg/kg diet) are sufficient to prevent the damage. Thus, our results caution against the interpretation of DNA data obtained from frozen rat tissues or cells in animal studies with dietary vitamin E or Se deficiencies.