Postnatal patterns of fatty acids in brain of progeny from vitamin B-6 deficient rats before and after pyridoxine supplementation

The influence of deficient and adequate maternal intakes of pyridoxine on lipid profiles in brains of progeny at 5, 10, 15, 25 and 50 days of age was studied. The effects of supplementing deficient dams at two different times with pyridoxine on the brain development of progeny were also examined. Three groups of weanling, female rats were fed diets deficient in pyridoxine (1.2 mg pyridoxine-HC1/kg diet) and another group received a control diet (30.0 mg pyridoxine-HC1/kg diet). One deficient group and the control group were fed their diets throughout growth, gestation and lactation. Two groups of dams were fed the deficient diet through growth, gestation and until 5 or 10 days postpartum when pyridoxine was supplemented by feeding the control diet. Body and brain weights were significantly lower in 15, 25 and 50 day-old progeny of deficient dams and deficient dams supplemented at 10 days postpartum. Cerebroside content at 15 days and ganglioside content at 15 and 25 days were significantly lower in brains of pups from unsupplemented deficient dams and deficient dams supplemented at 10 days postpartum. The postnatal development of cerebroside and ganglioside levels in brain was delayed or retarded in brain of pups from unsupplemented deficient dams. Supplementation of dams fed a low level of pyridoxine (1.2 mg/kg diet) with the vitamin beginning at 5 days postpartum reversed all observed effects of the low vitamin intake on brain lipids in progeny.     

Influence of vitamin B6 intake on the content of the vitamin in human milk

The influence of the level of vitamin B6 intake on the content of the vitamin in milk was studied in 19 healthy subjects whose stages of lactation ranged from 3 weeks to 30 months. Total vitamin B6 intakes, including extra-dietary sources of the vitamin, ranged from 1.3 to 12.5 mg per day with six subjects consuming less than the recommended allowance of 2.5 mg per day (RDA, 1974). Subjects consuming less than 2.5 mg of vitamin B6 per day had significantly less vitamin B6/liter milk (129 mug) than groups consuming 2.5 to 5.0 or greater than 5.0 mg per day (239 and 314 mug, respectively). Among subjects consuming greater than 2.5 mg of vitamin per day the stage of lactation did not influence the levels of protein or vitamin B6 in milk. Vitamin B6 intakes two to five times the recommended allowance did not significantly elevate the level of the vitamin in milk compared to values for subjects whose intakes approximated the allowance. The vitamin B6/protein ratio in milk of subjects consuming less than 2.5 mg vitamin B6 per day was 13 mug/g and was significantly lower than that observed for the other two groups (23 and 28 mug/g). Daily and weekly variations of the vitamin B6 and protein content in milk of individuals were small. However, marked diurnal variations in the vitamin B6 content were found in milk of individuals taking daily supplements of the vitamin with peak levels occurring in the afternoon 3 to 5 hr after supplements were taken in the morning.     

Dietary excess of vitamin B-6 affects the concentrations of amino acids in the caudate nucleus and serum and the binding properties of serotonin receptors in the brain cortex of rats

Vitamin B-6 is a cofactor in many reactions of nitrogen metabolism. Deficiency alters tissue amino acid concentrations but effects of excess vitamin B-6 have not been well described. We fed female rats (218 g, 7 per group) 1 (control), 10, 100, 175 or 250x) the National Research Council recommended level of pyridoxine HCl (7 mg/kg) for 10 wk and measured serum amino acids, amino acids and neurotransmitters in brain regions and the binding properties of serotonin receptors in the cerebral cortex using a ketanserin binding assay. Rats were decapitated, and unheparinized blood was obtained. In the caudate nucleus, concentrations of glutamate, threonine, taurine, methionine, gamma-amino-butyric acid and the sum of the essential amino acids in groups 10X and 100X were approximately 130 to 180% of control levels (P < 0.05); groups 1X, 175X and 250X were not different. A similar pattern was seen in the serum for serine, glycine, aspartate and ornithine; the latter two amino acids increased to over 200% of control in group 100X. In the ketanserin binding assay, both the antagonist binding affinity and the maximal number of binding sites were higher for group 100X than for 1X, 175X and 250X, and were higher for 10X than for 1X. Norepinephrine in the raphe nucleus followed a similar biphasic pattern. Excess dietary pyridoxine affected brain and serum concentrations of some amino acids and binding properties of cortical serotonin receptors in a biphasic pattern over the range of concentrations fed in this study.     

Biotin deficiency in chicks fed a wheat-based diet

A wheat-based diet produced severe biotin deficiency symptoms appearing at the age of ten to fourteen days and becoming very severe in the third and fourth week (group 1). Biotin supplementation with 50 mug/kg (group 2) reduced the symptoms almost completely, but did not restore completely growth compared to chicks receiving the diet supplemented with 300 mug biotin/kg compared to chicks receiving the diet supplemented with 300 mug biotin/kg (group 3). The plasma level of biotin was about, or lower than, 100 ng/100 ml plasma in groups 1 and 2, indicating biotin deficiency. In group 3, plasma biotin was above 200 ng/100 ml. Liver biotin, after two weeks, was low in group 1 (less than 600 ng/g), medium in group 2 (1000 to 1500 ng/g) and in group 3 above 2000 ng/g. Plasma and liver biotin levels are found to be suitable parameters for diagnosis of subclinical biotin deficiency in chicks.     

Growth response of the yeasts Saccharomyces uvarum and Kloeckera brevis to the free biologically active forms of vitamin B-6

The ideal microorganism for the microbiological assay of total vitamin B-6 should respond equally to all forms of vitamin B-6. The yeasts Saccharomyces uvarum (ATCC 9080) and Kloeckera brevis (ATCC 9774) were compared in their ability to utilize pyridoxine, pyridoxal and pyridoxamine in the concentration range needed for the measurement of vitamin B-6 in biological materials. Our results showed that K. brevis responded equally to all three free forms of vitamin B-6 at a dosage range of 2--10 ng molar equivalent of pyridoxine. In contrast, S. uvarum, which is currently widely used for the vitamin B-6 assay, had a significantly different growth response to three forms of vitamin B-6 at the comparable dosage range. The results suggest that the yeast K. brevis is better suited for the microbiological assay of total vitamin B-6.     

Lipid peroxidation in vivo during vitamin E and selenium deficiency in the rat as monitored by ethane evolution

Ethane evolution was monitored from vitamin E and selenium (Se)-deficient rats to determine if lipid peroxidation occurs in vivo when these rats develop fatal organ lesions. Weanling rats were fed a vitamin E and Se-deficient, or supplemented, diet for 40 to 90 days. Each was then prefasted for 4 hours and fasting was continued for 24 to 40 hours while ethane was collected. Approximately 50% of the doubly-deficient rats died as a result of fasting. Pathological signs included hematuria, lung hemorrhage, and liver necrosis. Ethane evolution increased exponentially 10 to 20 hours before death and then declined 2 hours before death. Rats that survived (at least 5 days after ethane collection) evolved 7.4+/-1.3 nmoles ethane/100 g body weight/24 hours compared to 100+/-6 for rats that died. Supplementation of the basal diet with vitamin E (200 IU/kg), Se (0.2 ppm, as Na2SeO3), or both, completely prevented mortality and reduced ethane evolution values to 0.4+/-0.2, 3.1+/-0.4, or 0.2+/-0.2, respectively. These experiments indicate that lipid peroxidation occurs in vivo as a result of vitamin E and Se deficiency, and the peroxidation process greatly accelerates during the terminal phase of the fatal disease.     

The effect of vitamin B12 on the tolerance of chicks for high levels of dietary fat and carbohydrate

Three experiments were conducted with White Leghorn chicks hatched from hens fed diets varying in levels of protein, fat, and vitamin B12. Adding animal fat at a level of 10% in the chick diet caused growth depression of vitamin B12 deficient chicks, regardless of protein or energy level of hen or chick diet. Increasing the level of fat to 20% in the chick diet caused further growth depression and increased mortality. Feed efficiency of vitamin B12 deficient chicks was severely depressed by each additional increment in the fat level. Increasing protein content from 20 to 30% in the chick diet resulted in severe growth depression and poor feed efficiency. Although the added fat in the 30% protein chick diet depressed growth of chicks hatched from hens fed the 16 and 32% protein with added fat, it improved growth of those hatched from hens fed the similar diets with no added fat. Added fat in the 30% protein chick diet also improved feed efficiency of all chicks regardless of breeder diet treatments. Chicks hatched with an adequate carry-over of vitamin B12 from hens or chicks fed a diet with 10 micrograms of added vitamin B12/kg of feed did not show the growth depression caused by the high level of fat in the 20 and 30% protein chick diets. Feed efficiency was greatly improved by the addition of vitamin B12 to all chick diets. In a 22% protein vitamin B12 deficient diet, isocaloric substitution of glucose for fat depressed chick growth significantly and this growth depression was counteracted by supplementing the diet with 10 or 100 micrograms of vitamin B12/kg of feed. The vitamin B12 requirement was not increased by such substitution in the 22% protein diet. In contrast, isocaloric substitution of fat for glucose in the 32% protein chick diet increased the vitamin B12 need for optimum growth.     

Copper, iron, and zinc contents of mature human milk

Daily, weekly, and within-day variations in copper, iron, and zinc contents of human milk were investigated in order to determine whether one sample from an individual is representative of these elements. Total solids, fat, and protein contents were also measured. Fifty women in their 6th to 12th week of lactation each provided seven milk samples consisting of five consecutive daily samples and two additional samples collected either within a single day or at weekly intervals. Fat varied the most of all constituents and total milk solids reflected this variability. Values ranged from 0.2 to 10.4 g/100 ml for fat and from 8.58 to 17.49 g/100 ml for total solids. Protein varied from 0.76 to 2.04 g/100 ml among individuals, with little variation within an individual. Copper content varied considerably among women and within the same woman. With a large proportion of low values, the range was 0.09 to 0.63 mug/ml. Iron content was also found to vary within women as well as among women. Values ranged from less than 0.1 to 1.6 mug/ml with a preponderance of low values. Zinc content was more evenly distributed over the range of 0.14 to 3.95 mug/ml,and within an individual it did not vary widely. A representative estimate of copper and iron contents would therefore require multiple samples, whereas only one sample may provide a representative estimate of zinc content. Comparison of morning, midday, and evening values showed that copper and zinc are higher in the morning and iron is lower at this time. Increased amounts of copper, iron, and zinc were found in multiparous women whether or not they had previously lactated. Milk from older women had lower iron and higher copper and zinc contents than that from younger women. No differences were found in milk of women receiving dietary mineral and vitamin supplements. Calculations indicated that fully breast fed infants under 3 months of age receive approximately 0.35 mg/kg per day of zinc and 0.05 mg/kg per day of both copper and iron.     

Effect of chronic hypovitaminosis A on water metabolism in the weanling rat

To study water imbalance reported to occur in vitamin A deficiency, chronic hypovitaminosis A was produced in 7-week old rats by feeding deficient or adequate vitamin A (12 or 256 mug/kg body weight/day, respectively) for a comparison period of 6 weeks. In the case of the deficient rats, these were partially depleted of their vitamin A stores prior to feeding the 12 mug intake. At the termination of the comparison period, the deficient rats exhibited elevated cerebrospinal fluid pressure and lower plasma and liver vitamin A concentrations. Based upon kinetics of a single intrajugular injection of 3H2O and 14C-inulin, total body water, extracellular water and renal clearances were lower in vitamin A deficient rats. However, when these criteria were expressed on a body weight basis, there were no significant differences. The turnover of total body water was reduced in the hypovitaminotic A rats. The results are discussed in terms of an inhibitory effect of vitamin A deficiency on growth.     

Dietary selenium- and vitamin E-induced alterations in some rabbit tissues

The present study was designed to investigate and compare the effects of dietary selenium (Se) and vitamin E on some physiological parameters and histological changes in liver, heart, and skin tissues, as well as the blood parameters and the related enzymes. Both sex young rabbits were fed with deficient (9.8 micrograms/kg diet), adequate (225 micrograms/kg diet), and rich (4.2 mg/kg diet) Se and vitamin E diets for 12-15 wk for this purpose. As the plasma Se levels and the erythrocyte glutathione (GSH) peroxidase activity decreased (79.8 +/- 9.4 ng/mL and 2.0 +/- 0.3 U/g Hb, respectively) in the deficient group, these values increased (100.4 +/- 2.7 ng/mL and 14.5 +/- 4.3 U/g Hb) in the rich group significantly with respect to the control group. The other antioxidant enzyme activities and the related element levels did not change significantly in either one of the experimental groups. Although the platelet counts of the two experimental groups were not different from the control values, the collagen and the adenosine diphosphate (ADP) stimulated platelet aggregation rate and intensity increased in the deficient group (p < 0.05) and decreased very significantly (p < 0.001) in the rich group. In both of the experimental groups, as the percentage values of the neutrophils decreased, the lymphocytes and the eosinophils increased significantly. According to the light microscopic investigations, the observed lesions of considerable intensity within the tissues that elicit cell degenerations were more pronounced in the animals fed with the rich diet than in those fed with the deficient diet. The deficiency as well as toxicity of Se and the deficiency of vitamin E caused several alterations in the physiological functions of the tissues, and these alterations were supported by the histological lesions within these tissues.     

Vitamin E modulation of hepatic focal lesion growth in mice

The effect of DL-alpha-tocopherol acetate (vitamin E) on hepatic focal lesion growth in male B6C3F1 mice previously treated with diethylnitrosamine (DEN) was investigated. After hepatic focal lesions were formed, mice were placed into one of the following dose groups: 0 mg vitamin E/kg NIH-07 diet, 50 mg vitamin E/kg NIH-07 diet (control diet), 250 mg vitamin E/kg NIH-07 diet, and 450 mg vitamin E/kg NIH-07 diet. Mice were euthanized after either 30 or 60 days of dietary treatment. In normal (nonlesion) liver, vitamin E deficiency (0 mg/kg diet) increased hepatic DNA synthesis. In addition, vitamin E supplementation (450 mg/kg diet) decreased the incidence of hepatic apoptosis, while vitamin E deficiency (0 mg/kg diet) increased the incidence of hepatic apoptosis. The effect of vitamin E-induced lesion growth was examined by measuring the number of focal lesions per liver and the relative focal lesion volume. High-dose vitamin E supplementation (450 mg/kg diet) appeared to enhance the growth of hepatic focal lesions. In particular, basophilic lesions appeared to be the most sensitive to high-dose vitamin E modulation (450 mg/kg diet) as evidenced by increased number, volume, and labeling index of hepatic focal lesions. Vitamin E deficiency also appeared to enhance the growth of hepatic focal lesions, though to a lesser extent than vitamin E supplementation (450 mg/kg diet). In the present study, both vitamin E supplementation (450 mg/kg diet) and deficiency (0 mg/kg diet) appeared to enhance focal lesion growth albeit neither treatment enhanced lesion growth as dramatically as known nongenotoxic hepatocarcinogens (e.g., phenobarbital and dieldrin). The data presented here suggest that oxidative stress in focal hepatocytes may be a component of the liver tumor promotion process.     

The effects of selenium deficiency, dietary selenium, and vitamin E supplementation on the oxidative status of pig liver

The aim of this work was to determine the effect of selenium (Se) deficiency on the porcine liver oxidative stability and to investigate Se content and oxidative status in porcine liver after dietary supplementation with vitamin E (vit E), sodium selenite, and selenized yeast. Experimental animals were fed a basal corn meal, low in Se and vit E, for a 4-week depletion period before being given the experimental diets containing different levels of Se and/or vit E for 5 months. Dietary treatments were the basal diet with no additions (control); the basal diet supplemented with 25 mg of vit E/kg of feed (group I); basal diet + 0.3 mg selenite-Se/kg (group II); basal diet + 0.3 mg selenized yeast-Se/kg (group III); basal diet + 0.1 mg selenite-Se + 10 mg vit E/kg (group IV); and basal diet + 0.3 mg selenite-Se + 25 mg vit E/kg (group V). The Se content in pig liver samples was 33 to 192% lower in the control group than in all the other groups. Dietary Se from selenized yeast had a more pronounced effect on Se level than dietary sodium selenite. The highest Se content was found in liver samples from the Se + vit E supplemented group (group V). All the dietary supplementation schemes significantly improved the oxidative status of porcine liver compared with the control group samples. The best results were obtained by simultaneous dietary supplementation with Se + vit E (groups IV and V) > group III > group II > group I.     

Pharmacokinetic parameters of sisomicin

Sisomicin in doses of 1 mg/kg was administered intramuscularly to 10 healthy volunteers, and 1 week later the same volunteers received sisomicin at the same dose intravenously. A peak serum concentration of sisomicin of 3.08 mug/ml was obtained 1 h after intramuscular injection, and a peak serum concentration of 7.12 mug/ml was achieved 30 min after a 30-min intravenous infusion. The sisomicin elimination data were analyzed according to a two-compartment model. Pharmacokinetic parameters derived from the intramuscular and intravenous studies were quite similar.     

Fluorescent lipid oxidation products and heme spectra index antioxidant efficacy in kidney tissue of hamsters

Studies ranging from epidemiological to molecular suggest that dietary antioxidants protect against chronic diseases. The hypothesis was investigated that hamster kidney homogenate are better protected against induced oxidative damage after animals were fed a purified vitamin E deficient diet supplemented with 30 international units (IU) vitamin E/kg (30 IU diet) than fed the minimum required 3 IU vitamin E/kg (3 IU diet). The addition of 200 mg (+)-catechin to the 3 IU diet may offer protection. The effects of dietary (+)-catechin and alpha-tocopherol on tissue oxidizability were investigated by measuring (i) fluorescent products in lipid extracts, (ii) heme protein oxidation and (iii) heme destruction. A rapid initial increase of oxidation markers was measured over the 4 h incubation period for iron + ascorbate induced oxidation and a constant increase for lipoxygenase catalyzed products. Analysis of covariance over time and comparison at specific incubation times showed that iron + ascorbate induced homogenates from hamsters fed the 30 IU diet generated less fluorescent products and oxidized heme proteins than homogenates from the 3 IU or the 3 IU plus (+)-catechin fed animals. Incubation with lipoxygenase produced more lipid fluorescent products and heme protein oxidation in the 3 IU than in the 30 IU vitamin E group. In conclusion, supplementary dietary vitamin E but not supplementary (+)-catechin in a diet containing the minimum requirement of vitamin E for the species enhances oxidative resistance of kidney tissue.     

Organoleptic evaluation of eggs produced by laying hens fed diets containing graded levels of flaxseed and vitamin E

Eighteen-week-old laying hens were fed diets containing 0, 10, or 20% ground flaxseed and 10 or 100 IU vitamin E/kg diet, in a factorial arrangement. When birds were 60 wk of age, eggs were collected from various treatments and used in taste panel studies. All studies involved freshly boiled eggs. In Experiment 1, four separate panels were conducted to obtain information on egg aroma, egg flavor, presence of any off-flavor, and overall acceptability of the egg. Pooled data showed a very significant difference among panelists for all attributes tested (P < 0.01) and off-flavors were detected in eggs from hens fed 10 and 20% flaxseed with 10 mg vitamin E/kg. In Experiment 2 panelists were asked to evaluate egg aroma, yolk flavor, and overall acceptability in eggs from birds fed the lowest level of vitamin E with 0 or 10% flaxseed, and birds fed 20% flaxseed and 10 or 100 mg vitamin E/kg. The highest ratings for egg aroma, yolk flavor, and overall acceptability were for the control eggs. There was a significant reduction in overall acceptability as flaxseed concentration increased (P < 0.05) and an interesting and significant (P < 0.05) decline in overall acceptability for birds fed 100 vs 10 IU vitamin E/kg diet in eggs for birds fed 20% flaxseed. In a third study, there was an indication of preference for eggs from birds not fed flaxseed, when the diet contained 10, rather than 100 IU vitamin E/kg diet. These data suggest that high (> 10%) levels of flaxseed used in the bird's diet will result in some decrease in overall egg acceptability as assessed by aroma and flavor. These effects seem to be accentuated by using high levels of vitamin E in the bird's diet.     

Acute abdomen accompanying hepatic parenchymal changes

Total femur zinc of young rats was used to evaluate the biological availability of zinc in milk and soy protein-based infant formulas. A zinc deficient diet (0.8 mug Zn/g) containing egg white protein was supplemented with graded levels of zinc from zinc sulfate, milk and soy protein-based infant formulas. A plot of total femur zinc (log) after feeding the diet for 3 weeks versus the zinc added to the diet gave a linear relationship over the range of 0, 3, 6, 9 and 12 mug/g added zinc. By using a slope-ratio bioassay model, the relative biological availability of endogenous and added zinc in milk-based formula was estimated to be 0.86 and that of soy-based formula 0.67 (zinc sulphate = 1.00) with corresponding 95% fiducial limits being 0.82 to 0.91 and 0.62 to 0.71. Thus, to provide equivalent amounts of available zinc, the total zinc content of the soy protein-based formula would need to be at least 20% higher than that of the formula containing milk protein.     

Mechanism of steroid action in inflammation: inhibition of prostaglandin synthesis and release

Acute arthritis was induced by injection of cell-free extract of group A Streptococci into the knee joints of mature male rats. Slices of control and inflamed synovia were incubated for 30 to 240 minutes and the rate of prostaglandin E (PGE) released into the medium was measured by radioimmunoassay. PGE release from inflamed synovia was 5-8 fold higher than that in normal tissue. Incubation of inflamed synovia with corticosterone acetate, dexamethasone or prednisone (100 mug/ml) for one or four hours reduced PGE release by 33% and 55% respectively. Lower concentrations of corticosterone (10 - 30 mug/ml) were ineffective. Aldosterone and progesterone (100 mug/ml) had no effect on PGE release throughout the incubation period. Chloroquine (10 mug/ml) inhibited PGE release from inflamed synovia by 50%. Indomethacin (1 mug/ml) abolished PGE release by 90%. Corticosterone, dexamethasone and prednisone reduced PGE content of inflamed synovia by approximately 45% during a 4-h incubation period. Aldosterone and progesterone were ineffective, while indomethacin reduced PGE content by 70%. The suppressive action of corticosterone on PGE release was prevented by addition to the medium of arachidonic acid (2 mug/ml). By contrast, the inhibitory action of indomethacin was not affected by provision of exogenous substrate. We suggest that glucocorticosteroids reduce PGE release by limiting the availability of the substrate for prostaglandin biosynthesis, and this may well explain some of their anti-inflammatory properties.     

Vitamin requirements for the treatment of hyperhomocysteinemia in humans

We have previously shown that a modest vitamin supplement containing folic acid, vitamin B-12 and vitamin B-6 is effective in reducing elevated plasma homocysteine concentrations. The effect of supplementation of the individual vitamins on moderate hyperhomocysteinemia has now been investigated in a placebo-controlled study. One hundred men with hyperhomocysteinemia were randomly assigned to five groups and treated with a daily dose of placebo, folic acid (0.65 mg), vitamin B-12 (0.4 mg), vitamin B-6 (10 mg) or a combination of the three vitamins for 6 wk. Folic acid supplementation reduced plasma homocysteine concentrations by 41.7% (P < 0.001), whereas the daily vitamin B-12 supplement lowered homocysteine concentrations by 14.8% (P < 0.01). The daily pyridoxine dose did not reduce significantly plasma homocysteine concentrations. The combination of the three vitamins reduced circulating homocysteine concentrations by 49.8%, which was not significantly different (P = 0.48) from the reduction achieved by folate supplementation alone. Our results indicate that folate deficiency may be an important cause of hyperhomocysteinemia in the general population.     

Vitamin E and C levels in infants during the first year of life

The considerably lower vitamin E level found in cord blood and in newborns at birth than those found in the venous blood of mothers at delivery are not yet fully explained. In a group of 217 not selected newborns, we attempted to establish the relation between vitamin E and C levels at delivery and the changes during the first year of life. The mean serum vitamin E level rose from 0.37 mg/ml at 3 days to 0.80 mg/100 ml at 6 months and to 0.72 mg/100 ml at 12 months. On the other hand vitamin C mean levels lowered from 0.93 mg/100 ml in cord blood to 0.77 mg/100 ml at 6 months and to 0.73 mg/100 ml at 12 months. The rise of vitamin E values could be explained by the early use of infant solid foods with high vitamin and mineral content and by the increase of serum lipoproteins. Except at 3 days after delivery there were no individual values of serum vitamin E below the acceptable 0.35 mg/100 ml limit. However, serum vitamin C levels compatible with a moderate risk were very often observed, i.e., in 27.1% of infants at 6 months and in 30.5% at 1 year. Thus, vitamin E intake in infants was satisfactory with the usual diet but not vitamin C for which blood levels were not adequate. In view of these findings it appears necessary to evaluate periodically the vitamin E as well as vitamin C status in the infant population.     

Effect of a necrogenic dose of diethylnitrosamine on vitamin E-deficient and vitamin E-supplemented rats

In order to evaluate the effects of a necrogenic dose of diethylnitrosamine (DEN) on vitamin E-deficient and vitamin E-supplemented rats, a single dose of the drug (200 mg/kg body weight) was injected intraperitoneally at the end of 10 weeks of treatment with the diets. The hepatic necrosis and lipoperoxidation provoked by DEN were evaluated 24, 48, 72 and 120 hours after the injection and were found to be more intense in the deficient group (thiobarbituric acid reactive substances (TBARS): 5.20 +/- 1.48 nmol/mg protein; necrosis volume: 68.99 +/- 8.36%; P < 0.05) during the second period. Also, in the same group and during the same period, mean plasma and hepatic vitamin E concentrations and mean liver glutathione concentration were the lowest detected, suggesting the occurrence of antioxidant consumption due to the toxic action of DEN. In contrast to vitamin E deficiency, which permitted the drug to exert stronger toxic effects, 20-fold supplementation with vitamin E did not provide additional protection against the lipoperoxidation and necrosis provoked by DEN (P < 0.05). The results suggest that other mechanisms in addition to lipoperoxidation provoked by free radicals originating from the metabolism of nitrosamines by the cytochrome P-450-dependent enzymatic system may be involved in the hepatotoxic action of these substances.