Mutagens in feces from vegetarians and non-vegetarians

Mutagens in water extracts from feces of persons in 3 different diet groups were measured with the fluctuation test for weak mutagens using Salmonella typhimurium TA100 and TA98 as tester strains. The 3 diet groups were ovo-lacto vegetarians (N = 6), strict vegetarians (N = 11) and non-vegetarians (N = 12). All subjects were from the urban area of Vancouver, British Columbia, Canada. On TA100 ovo-lacto vegetarians and strict vegetarians had significantly lower levels of fecal mutagens than non-vegetarians (P less than or equal to 0.025 and P less than 0.010, resp.). The same pattern, although less significant, was obtained with TA98. Correlation studies between mutagenicity on TA100 and TA98 and between the pH of the fecal homogenate and mutagenicity indicate the presence of 2 or more major fecal mutagens.     

Antioxidant protection of phospholipid bilayers by alpha-tocopherol. Control of alpha-tocopherol status and lipid peroxidation by ascorbic acid and glutathione

Factors affecting the balance between pro- and antioxidant effects of ascorbic acid and glutathione were studied in soybean phosphatidylcholine liposomes challenged with Fe2+/H2O2. Effective antioxidant protection by alpha-tocopherol appeared to be due to efficient reaction with lipid oxy-radicals in the bilayer rather than to interception of initiating oxygen radicals. At concentrations above a threshold level of approximately 0.2 mol % (based on phospholipid content), alpha-tocopherol completely suppressed lipid oxy-radical propagation, which was measured as malondialdehyde production. Both ascorbic acid and glutathione, alone or in combination, enhanced lipid oxy-radical propagation. Alpha-Tocopherol, incorporated into liposomes at concentrations above its threshold protective level, reversed the pro-oxidant effects of 0.1-1.0 mM ascorbic acid but not those of glutathione. Ascorbic acid also prevented alpha-tocopherol depletion. The combination of ascorbic acid and subthreshold levels of alpha-tocopherol only temporarily suppressed lipid oxy-radical propagation and did not maintain the alpha-tocopherol level. Glutathione antagonized the antioxidant action of the alpha-tocopherol/ascorbic acid combination regardless of alpha-tocopherol concentration. These observations indicate that membrane alpha-tocopherol status can control the balance between pro- and antioxidant effects of ascorbic acid. The data also provide the most direct evidence to date that ascorbic acid interacts directly with components of the phospholipid bilayer.     

Bile acid metabolism in partially hepatectomized rats

The bile flow and the bile acid secretion, calculated on liver weight basis, increased 12 H and 24 H after 60-70% hepatectomy and returned to the initial levels thereafter. The biliary phospholipid secretion much more increased than bile acids, but the cholesterol secretion decreased. Bile acid composition changed with an increase of the cholic acid group and a decrease of the chenodeoxycholic acid group in both bile and feces. These changes almost disappeared on Day 14. The pool size of bile acid decreased maximally on Day 4 to about 40% of the initial, but the distribution of bile acids in the enterohepatic circulation was not changed. The fecal cholesterol and coprostanol markedly decreased on Day 2 but gradually returned to the initial levels according to the recovery of diet intake. The fecal bile acids decreased on Day 2, increased on Day 4, and returned to the normal range after Day 7. In conclusion, the regenerating liver secretes more bile, bile acids and phospholipids, and less cholesterol than the normal liver. Cholic acid predominates in the bile acids. These changes restored to the initial levels by about one week after the operation.     

Secretion of alpha-tocopherol from cultured rat hepatocytes

Primary cultures of rat hepatocytes and rat liver perfusions were used to study hepatic secretion of alpha-tocopherol. The secretion of alpha-tocopherol from hepatocytes in culture was linear with time for 4 h. Ultracentrifugation of the medium revealed that 89.4 +/- 2.1% of alpha-tocopherol secreted during 4 h incubation was associated with the very-low density lipoprotein fraction (VLDL, d less than 1.006 g/ml). Oleic acid had no significant effect on the secretory rate of alpha-tocopherol, whereas eicosapentaenoic acid reduced the amount of alpha-tocopherol secreted to 48.4 +/- 12.7% of the control value after 20 h incubation (P less than 0.01). Monensin, a known inhibitor of VLDL secretion, reduced the secretion of alpha-tocopherol to 14.1 +/- 4.3% of the control value (P less than 0.02). Colchicine and chloroquine inhibited the secretion of alpha-tocopherol in the same order of magnitude as monensin. Hepatic perfusion after intravenous injection of in vivo labeled alpha-[3H]tocopherol lymph, showed that about 75% of the secreted radioactivity was in the VLDL fraction. From these results we conclude that most alpha-tocopherol is secreted from the liver associated with nascent VLDL in rats.     

Lack of effect of experimental ascorbic acid deficiency on bile acid metabolism, sterol balance, and biliary lipid composition in man

Extensive studies in animal models indicate that subclinical ascorbic acid deficiency impairs the conversion of cholesterol to bile acid, elevates plasma cholesterol levels, and predisposes to development of cholesterol cholelithiasis. The present study was designed to see if this is also true in man. Five normal volunteers were hospitalized in a metabolic ward and placed on a controlled diet containing 3-4 mg of ascorbic acid each day. Ascorbic acid supplementation was given as follows: control period I (days 1-33), 75 mg/day; deficient period (days 34-96), 0 mg/day; and repletion period (days 97-101), 1000 mg/day. In addition, three of the subjects were studied during a second control period (days 102-139) during which they were given 75 mg/day of ascorbic acid. Ascorbate levels at the end of both control periods were 0.87-1.34 mg/dl in plasma and 19.4-29.5 micrograms/10(8) cells in leukocytes. At the end of the deficient period these levels were 0.09-0.15 mg/dl in plasma and 6.2-10.0 micrograms/10(8) cells in leukocytes, levels approaching those seen in scurvy. There was no effect of ascorbic acid deficiency on plasma cholesterol and triglycerides; plasma cholesterol in high, very low, and low density lipoprotein fractions; biliary lipid composition and saturation index of gallbladder bile; synthesis, fractional turnover, or pool size of either cholic or chenodeoxycholic acids; output of fecal acid or neutral sterols; and fecal sterol balance. Total bile acid pool size calculated by the one-sample technique was reduced 11% in the deficient period compared to control period I (P less than 0.005), and increased to 98.7% of the baseline levels in control period II. However, total bile acid pool calculated by the Lindstedt method did not change during deficiency. These data demonstrate that short-term subclinical ascorbic acid deficiency near the scorbutic range has no significant effect on bile acid and cholesterol metabolism in man.     

Reduction in hepatic lipid and plasma estradiol in estrogenized chicks injected with ascorbic acid

Injecting White Leghorn chicks every other day with 20 mg ascorbic acid significantly reduced the increase in liver weight and lipids caused by feeding a diet with 0.1% dienestrol diacetate. In chicks fed two different basal diets containing 0.1% dienestrol diacetate, injecting chicks every other day with 20 mg alpha-tocopherol did not significantly reduce liver weight or lipids while the ascorbic acid injections did. Injecting meat-type chicks implanted with estradiol with 10 mg ascorbic acid daily significantly reduced liver weight, liver lipids, and plasma estradiol, but injecting with 8 mg alpha-tocopherol daily had no significant effect.     

Evaluation of dietary essentiality of vitamins for Penaeus monodon (Fabricius)

The effect of exclusion of individual water-soluble (thiamine, riboflavin, pyridoxine, cyanocobalamin, pantothenic acid, folic acid, niacin, biotin, choline, inositol, ascorbic acid) and fat-soluble vitamins (vit. A, D, K and E) in semi-purified diets on growth and survival of juvenile shrimp, P. monodon was studied in the laboratory for 8 weeks. Diets lacking riboflavin and vitamin K did not affect growth and survival of shrimp. However, deletion of inositol and choline resulted in poor growth. Maximum growth was observed in the control diet (C1) which was supplemented with all vitamins. Diet deficient in ascorbic acid, biotin, folic acid, niacin, thiamine and alpha-tocopherol resulted in poor appetite and poorer feed conversion efficiency. All treatments except the control (C1) resulted in histological changes in the digestive gland cells. Detachment or destruction of the epithelial cells was observed in all treatments lacking individual vitamins but more severely in the treatment without a vitamin supplement followed by inositol, choline and ascorbic acid deficient diets.     

Lipid peroxidation and benzo[a]pyrene activation to mutagenic metabolites: in vivo influence of vitamins A, E and C and glutathione in both dietary vitamin A sufficiency and deficiency

Rats fed with either a sufficient-vitamin A or a vitamin A-free diet were pretreated with 750 mg/kg body weight of retinyl palmitate, alpha-tocopherol acetate, ascorbic acid or glutathione. Benzo[a]pyrene (BaP) metabolism and BaP-induced mutagenesis in Salmonella typhimurium TA98 were investigated and related to lipid peroxidation activities in postmitochondrial (S9) liver fraction. The microsomal mixed-function oxidase activities were decreased by vitamin A deficiency and weakly affected by scavenger treatment. The rate of lipid peroxidation of microsomal membranes was unaffected by vitamin A deficiency because of decreased polyunsaturated fatty acids and increased vitamin E contents. However, lipid peroxidation was decreased by pretreatment with fat-soluble vitamins (chiefly vitamin E) and increased by ascorbic acid. Within each experimental group both BaP metabolism and BaP mutagenic activity were closely correlated with the rate of lipid peroxidation. In vitamin A deficiency, the increased BaP metabolism and mutagenicity could be related to a decrease in cytosolic contents of scavengers (vitamin A and glutathione). In Ames test conditions, the free radical pathway became a route for BaP metabolism and thus the BaP activation to mutagenic metabolites is related to the cellular status in free radical scavengers.     

Ascorbic acid supplementation and copper status in rats

The effect of a high concentration (1%, w/w) of ascorbic acid in a Cu-adequate (150 μmol/kg) purified diet was studied in rats. After 6 wk, ascorbic acid had significantly reduced Cu concentrations in muscle and bone. The estimated whole body content of Cu in rats fed ascorbic acid was reduced by 20%. Within 1 d after oral administration of⁶⁴Cu, the recovery of the dose in feces was increased in rats fed ascorbic acid, suggesting that the vitamin depresses intestinal absorption of Cu. After intraperitoneal (ip) administration of⁶⁴Cu, the rate of loss of the dose from the body was decreased in rats fed ascorbic acid. This study suggests that the ascorbic acid induces a decreased efficiency of intestinal Cu absorption, which in turn triggers mechanisms to preserve Cu in the body stores. This is supported by the observation that the feeding of a Cu-deficient diet (5 μmol/kg) had similar effects, although more pronounced.     

Effect of wheat bran on excretion of radioactively labeled estradiol-17 beta and estrone-glucuronide injected intravenously in male rats.

Urinary and fecal estrogen excretion were studied in male rats fed a non-fiber wheat starch diet (dietary fiber less than 1%; NF group; n = 4), a low-fiber wheat flour diet (dietary fiber 2%; LF group; n = 4) or a high-fiber wheat bran diet (dietary fiber 11.6%; HF group; n = 3). Short-term effects of the experimental diet on estrogen excretion were studied after i.v. injection of 5 microCi (0.185 MBq) of [14C]estradiol-17 beta (E2) into the tail vein of the rats fed the diets for 2 days. After 3 weeks on the experimental diets, the long-term effects were studied after injection of 5 microCi of [14C]E2 and 10 microCi of [3H]estrone-3-glucuronide (E1-gluc). The diet was found to affect estrogen excretion. The short-term effect indicated that rats fed the HF diet excreted a relatively large amount of labeled compounds in the feces during the first day after injection, while rats fed the NF or the LF diets excreted about half that amount over the same period. On the other hand, urinary excretion of labeled compounds was significantly higher in the NF and LF rats. The long-term effect resulted in steeper slopes (P less than 0.05) of the fecal excretion profiles of rats fed the HF diet as compared with rats fed the NF and LF diets, indicating an accelerated fecal excretion of labeled compounds in the HF rats. The kinetic profiles of 14C and 3H radioactivity in blood plasma indicated a fast decrease (t1/2 of less than 2 min) for both [14C]E2 and [3H]E1-gluc. It was concluded that, owing to the short-term effect of wheat bran intake, during the first 24 h after i.v. administration relatively large amounts of radioactively labeled compounds are excreted in feces of rats fed the HF diet. In contrast, excretion is lower in urine of these rats. When the microflora is adapted to the experimental diet the wheat bran diet still results in an accelerated fecal excretion of labeled compounds, which might be attributed to an interruption of the enterohepatic circulation of estrogens. This might result in lowered plasma and/or tissue estrogen levels and hence a decreased exposure of estrogen-sensitive tissue to estrogens, which might decrease risk on mammary (breast) cancer development.     

Decreasing Effect of Chitosan on the Apparent Fat Digestibility by Rats Fed on a High-fat Diet

We investigated the effects of various dietary fibers or their likenesses on the apparent fat digestibility by rats fed on a high-fat diet. Each of 23 different fibers was added at 5% (w/w) to a purified diet containing 20% (w/w) corn oil. The rats were fed these diets for 2 weeks, and the feces were collected from each animal during the last 3 days. When compared with cellulose (control), 10 of the tested fibers significantly increased the fecal lipid excretion. Among these fibers, chitosan markedly increased the fecal lipid excretion and reduced the apparent fat digestibility to about a half relative to the control. The apparent protein digestibility was not greatly affected by chitosan. The fatty acid composition of the fecal lipids closely reflected that of the dietary fat. These results suggest that chitosan has potency for interfering with fat digestion and absorption in the intestinal tract, and for facilitating the excretion of dietary fat into the feces.     

Sesamin and alpha-tocopherol synergistically suppress lipid-peroxide in rats fed a high docosahexaenoic acid diet

Docosahexaenoic acid (DHA) is an essential nutrient for human health, but has extremely high oxidative susceptibility. We examined the suppressing effect of sesamin, a sesame seed lignan, on lipidperoxides in rats fed a low alpha-tocopherol and high DHA containing diet. Groups of rats were fed four experimental diets: low alpha-tocopherol (10 mg/kg diet) control diet, low alpha-tocopherol + 0.2% sesamin diet, low alpha-tocopherol + 0.5% DHA diet and low alpha-tocopherol + 0.5% DHA + 0.2% sesamin diet. TBARS concentrations in plasma and liver were significantly increased by DHA, but were completely suppressed by sesamin. Alpha-tocopherol concentrations in plasma and liver decreased by addition of DHA, but with sesamin recovered to the control level. The addition of DHA into the diets caused remarkable increases of DHA concentrations in plasma and liver lipids. Sesamin caused a significant increase of DHA concentrations in the triacylglycerol of plasma.     

Prebiotic oligosaccharides and the enterohepatic circulation of bile salts in rats

Human milk contains prebiotic oligosaccharides, which stimulate the growth of intestinal bifidobacteria and lactobacilli. It is unclear whether the prebiotic capacity of human milk contributes to the larger bile salt pool size and the more efficient fat absorption in infants fed human milk compared with formula. We determined the effect of prebiotic oligosaccharides on bile salt metabolism in rats. Rats were fed a control diet or an isocaloric diet containing a mixture of galactooligosaccharides (GOS), long-chain fructooligosaccharides (lcFOS), and acidified oligosaccharides (AOS) for 3 wk. We determined synthesis rate, pool size, and fractional turnover rate (FTR) of the primary bile salt cholate by using stable isotope dilution methodology. We quantified bile flow and biliary bile salt secretion rates through bile cannulation. Prebiotic intervention resulted in significant changes in fecal and colonic flora: the proportion of lactobacilli increased 344% (P < 0.01) in colon content and 139% (P < 0.01) in feces compared with the control group. The number of bifidobacteria also increased 366% (P < 0.01) in colon content and 282% in feces after the prebiotic treatment. Furthermore, pH in both colon and feces decreased significantly with 1.0 and 0.5 pH point, respectively. However, despite this alteration of intestinal bacterial flora, no significant effect on relevant parameters of bile salt metabolism and cholate kinetics was found. The present data in rats do not support the hypothesis that prebiotics naturally present in human milk contribute to a larger bile salt pool size or altered bile salt pool kinetics.     

Antioxidative status changes in golden syrian hamsters with experimental metabolic syndrome

Some indices of the antioxidant status (content of the alpha-tocopherol, reduced glutathione and ascorbic acid, activity of the glutathione reductase and aryl-esterase) and lipid peroxidation processes in the liver, blood serum, and some blood serum lipoprotein fractions of the Golden Syrian hamsters of different sex and age status under high-caloric diet were investigated. It has been shown that the hypercaloric diet leads to a decreaseng of reduced glutathione content and increase of the level of lipid peroxidation products in the liver of experimental animals. The ascorbic acids content in male liver is decreased and in female liver is increased. In the blood serum under hypercaloric nutrition the accumulation of lipid peroxidation products and alpha-tocopherol content a decrease in ApoB-lipoproteins and HDL is observed. Simultaneously the ascorbic acid content is increased in the blood serum of all experimental animals. Activation of free-radical oxidation both in the liver, and blood serum is more significant in males compared with females. The data obtained allow to suppose that atherosclerotic complications of metabolic syndrome development may be connected to the lipoprotein oxidant status infringement.     

布氏田鼠在不同光周期下对陌生个体尿液和粪便的气味辨别

研究了成年布氏田鼠在10min内,对不同光照周期下（长光照：LD;短光照：SD）陌生雌／雄个体尿液和粪便两种单一个体气味源的气味行为反应,实验发现：所有雌雄被试鼠对LD气味源比SD气味源表现出更多的嗅闻行为。LD和SD被试鼠对同性／异性尿液气味的嗅闻行为没有表现出明显的差别,但LD被试雄鼠对陌生雌鼠粪便的嗅闻频次显多于SD被试雄鼠,从嗅闻行为特征量（嗅闻行为占所有行为的百分比）来看,所有LD和SD被试雌,雄鼠对尿液的嗅 明显多于粪便,除SD粪便气味外,被试鼠对异性气味源的嗅闻明显多于同性,实验结果表明：作为两种个体气味源,尿液和粪便都带有季节性信息,而且是具有性别特性的。异性的个体气味源比同性的个体气味源更具吸引力;长光照动物的个体气味比短光照动物的气味更具吸引力。     

Changes in catecholamine metabolism by ascorbic acid deficiency in spontaneously hypertensive rats unable to synthesize ascorbic acid

We have previously reported the establishment of a novel rat strain, SHR-od, with both spontaneous hypertension and a defect of ascorbic acid biosynthesis. Blood pressure in mature SHR-od fed an ascorbic acid-supplemented diet is over 190-200 mmHg, while it decreased to around 120 mmHg at 4-5 weeks after the cessation of ascorbic acid supplementation. With regard to possible mechanisms of blood pressure lowering, we focused on catecholamine synthesis in adrenal glands, since catecholamine is a major factor for blood pressure regulation and ascorbic acid is a co-factor of dopamine beta-hydroxylase (DBH) in catecholamine biosynthesis. Male SHR-od (25-week-old) and normotensive ODS rats with a defect in ascorbic acid biosynthesis (25-week-old) were fed a Funabashi-SP diet with or without ascorbic acid (300 mg/kg diet) for 28 days or 35 days. In SHR-od, systolic blood pressure (191 +/- 6 mmHg) began to decrease from day 21 in the ascorbic acid-deficient group, whereas no significant difference was found in ODS rats. In spite of significant lowering of blood pressure, no significant differences were found in catecholamine levels in serum, adrenal glands and brain on day 28. On day 35, however, urinary excretion of norepinephrine and epinephrine in the ascorbic acid-deficient SHR-od were higher at 490% (P < 0.05) and 460% (P < 0.05) of the respective control. Serum catecholamine concentrations and the adrenal catecholamine content tended to be higher in the ascorbic acid-deficient SHR-od than the control of SHR-od and reached to similar level in ODS rats. The administration of ascorbic acid (intraperitoneal injection, 60 mg ascorbic acid/kg body weight, once a day) to the ascorbic acid-deficient SHR-od restored blood pressure to the range 180-190 mmHg within two days. These findings indicate that ascorbic acid deficiency affects catecholamine metabolism in the adrenal glands of SHR-od in response to blood pressure lowering, suggesting catecholamines are not involved in the mechanism for the remarkable reduction in blood pressure in response to ascorbic acid deficiency.     

Analyses of constituents of feces and the effect of a vitamin B12 fortified diet on coprophagy in the mouse

In order to investigate coprophagy from the viewpoint of nutrition, fecal constituents were analyzed in freeze-dried samples. Feces were collected from 7:00 to 11:00 and from 19:00 to 23:00. Inorganic elements and crude fibers per unit weight were 3-4 times more concentrated in feces than in basal diet, whereas, crude proteins, crude fats and nitrogen-free extract showed various degrees of reduction. There were no differences in these tendencies with sampling time. As for some B vitamins, feces collected from 7:00 to 11:00 contained 22-92% more vitamins than feces collected from 19:00 to 23:00. In comparison with the dietary concentration, vitamin B12 was increased by 124-197 times (520-730 micrograms/100 g) in feces collected between 7:00 and 11:00. Folic acid in feces collected between 7:00 and 11:00 was 10 times greater than that in the diet. On the basis of the findings on vitamins, the effect of a vitamin B12 fortified diet (1,350 micrograms/100 g) on coprophagy was examined. Mean frequency of coprophagy per animal per day was 9.6 when animals were fed on the basal diet, whereas the frequency was immediately and significantly (p less than 0.05 approximately p less than 0.01) reduced to 4.7 after the diet had been replaced by the fortified one. However, coprophagy was not completely inhibited by vitamin B12 fortification. This indicates that some nutrient(s) in feces other than vitamin B12 might be of use to the host, and that otherwise, coprophagy might be a basically habitual form of behavior. Furthermore, under the fortified diet, the frequency of coprophagy increased gradually.(ABSTRACT TRUNCATED AT 250 WORDS)     

beta-Carotene: interactions with alpha-tocopherol and ascorbic acid in microsomal lipid peroxidation

beta-Carotene, alpha-tocopherol, and ascorbic acid were tested for their ability to inhibit, enhance, or react synergistically with O(2) (15, 150, 760 torr) and, 2,2'-azobis (2-amidino-propane) dihydrochloride (AAPH) or 1,1'-azobis (cyclohexane-carbonitrile) (ACCN) in isolated rat liver microsomes. beta-Carotene did not protect against lipid peroxidation, i.e., malondialdehyde (MDA) formation, in microsomal samples incubated at 37 degrees C with aqueous soluble AAPH at all added beta-carotene concentrations and oxygen tensions. More MDA (16%, p < 0.001) was produced at 15 torr of O(2,) and 160 nmol/mg protein of beta-carotene compared to respective vehicle control. Individually, alpha-tocopherol and ascorbic acid exhibited antioxidant protection (ascorbic acid &z.Gt; alpha-tocopherol); however, a mixture of both compounds was no more protective than ascorbic acid alone. beta-Carotene demonstrated a concentration-dependent antioxidant affect at 15 torr O(2) (p < 0.01); but a prooxidant effect at higher O(2) at 150 and 760 torr (>57%, p < 0.001) by lipid-soluble ACCN. alpha-Tocopherol exhibited concentration-dependent inhibitory effects on microsomal MDA formation at all oxygen tensions, but was most effective under 150 torr. Ascorbic acid demonstrated a concentration-dependent antioxidant effect only at 150 torr. ACCN-induced lipid peroxidation was no greater for the combination of the three compounds than ascorbic acid added alone. Thus, antioxidant or prooxidant activities for beta-carotene, alpha-tocopherol, and ascorbic acid in microsomal suspensions are related to O(2) tension, solubility, antioxidant concentrations and are governed by complex interactions. Differences between AAPH- and ACCN-induced lipid peroxidation are related to differences in lipid solubility.     

Dietary zinc restriction in rats alters antioxidant status and increases plasma F2 isoprostanes

Approximately 12% of Americans do not consume the estimated average requirement for zinc and could be at risk for zinc deficiency. Since zinc has proposed antioxidant function, inadequate zinc consumption may lead to an enhanced susceptibility to oxidative stress through several mechanisms, including altered antioxidant defenses. In this study, we hypothesized that dietary zinc restriction would result in lower antioxidant status and increased oxidative damage. We fed weanling Sprague-Dawley rats (n=12 per group) a zinc-adequate (50 mg/kg of zinc) diet, a zinc-deficient (<0.05 mg/kg of zinc) diet or a pair-fed diet for 3 weeks and then assessed their antioxidant status and oxidative stress parameters. Rats were zinc deficient as indicated by a significant (P<.05) reduction in body weight (49%) and 19% lower (P<.05) hepatic zinc (20.6+/-2.1 mg/kg) as compared with zinc-adequate rats (24.6+/-2.2 mg/kg). Zinc deficiency resulted in elevated (P<.05) plasma F(2) isoprostanes. Zinc deficiency-mediated oxidative stress was accompanied by a 20% decrease (P<.05) in the ferritin-reducing ability of plasma assay and a 50% reduction in plasma uric acid (P<.05). No significant change in plasma ascorbic acid or in plasma alpha-tocopherol and gamma-tocopherol was observed. However, hepatic alpha-tocopherol and gamma-tocopherol concentrations were decreased by 38% and 27% (P<.05), respectively, as compared with those in zinc-adequate rats. Hepatic alpha-tocopherol transfer protein levels were unaltered (P>.05) by zinc deficiency, but cytochrome P450 (CYP) 4F2 protein levels were elevated (P<.05) as compared with those in zinc-adequate rats. Collectively, zinc deficiency increased oxidative stress, which may be partially explained by increased CYP activity and reductions in hepatic alpha-tocopherol and gamma-tocopherol and in plasma uric acid.     

Acute and chronic effects of ethanol on secretion of alpha-tocopherol from primary cultures of rat hepatocytes

Primary cultures of rat hepatocytes were used to study the effect of acute and chronic ethanol exposure on alpha-tocopherol content in cells and media. Cells treated acutely with 60 mM ethanol secreted 74.5 +/- 18.0% (P less than 0.05), and their cellular alpha-tocopherol content was 85.7 +/- 15.4% (not significant) of controls after 20 h incubation. At this time total recovery of alpha-tocopherol was significantly reduced in ethanol-exposed cells (43.1 +/- 8.4%) as compared to control cells (52.8 +/- 5.0%, P less than 0.05). Hepatocytes isolated from chronic ethanol-fed rats (35% of total energy intake as ethanol for 5 weeks) secreted 41.9 +/- 12.7% less alpha-tocopherol than did cells of pair-fed controls during 20 h incubation (P less than 0.05). The amount of alpha-tocopherol secreted was then 15.6 +/- 4.2 and 19.8 +/- 3.8% of cell-associated alpha-tocopherol at start of incubation for chronic ethanol-fed and control rats, respectively (P less than 0.05). When 60 mM ethanol was added to the incubation medium, hepatocytes of control rats secreted significantly less alpha-tocopherol (about 30%, P less than 0.05), whereas alpha-tocopherol secretion was not significantly reduced in hepatocytes of chronic ethanol-fed rats. We conclude that both acute and chronic ethanol exposure reduce alpha-tocopherol secretion from rat hepatocytes.