Alpha tocopherol levels in various regions of the central nervous systems of the rat and guinea pig

Mitochondria dysfunction induced by decyl-TPP mitochondriotropic antioxidant based on caffeic acid AntiOxCIN6 sensitizes cisplatin lung anticancer therapy due to a remodeling of energy metabolism

The pharmacological interest in mitochondria is very relevant since these crucial organelles are involved in the pathogenesis of multiple diseases, such as cancer. In order to modulate cellular redox/oxidative balance and enhance mitochondrial function, numerous polyphenolic derivatives targeting mitochondria have been developed. Still, due to the drug resistance emergence in several cancer therapies, significant efforts are being made to develop drugs that combine the induction of mitochondrial metabolic reprogramming with the ability to generate reactive oxygen species, taking into consideration the varying metabolic profiles of different cell types. We previously developed a mitochondria-targeted antioxidant (AntiOxCIN6) by linking caffeic acid to lipophilic triphenylphosphonium cation through a 10-carbon aliphatic chain. The antioxidant activity of AntiOxCIN6 has been documented but how the mitochondriotropic compound impact energy metabolism of both normal and cancer cells remains unknown. We demonstrated that AntiOxCIN6 increased antioxidant defense system in HepG2 cells, although ROS clearance was ineffective. Consequently, AntiOxCIN6 significantly decreased mitochondrial function and morphology, culminating in a decreased capacity in complex I-driven ATP production without affecting cell viability. These alterations were accompanied by an increase in glycolytic fluxes. Additionally, we demonstrate that AntiOxCIN6 sensitized A549 adenocarcinoma cells for CIS-induced apoptotic cell death, while AntiOxCIN6 appears to cause metabolic changes or a redox pre-conditioning on lung MRC-5 fibroblasts, conferring protection against cisplatin. We propose that length and hydrophobicity of the C10-TPP+ alkyl linker play a significant role in inducing mitochondrial and cellular toxicity, while the presence of the antioxidant caffeic acid appears to be responsible for activating cytoprotective pathways.

Mitochondriotropic antioxidant based on caffeic acid AntiOxCIN4 activates Nrf2-dependent antioxidant defenses and quality control mechanisms to antagonize oxidative stress-induced cell damage

Mitochondria are key organelles involved in cellular survival, differentiation, and death induction. In this regard, mitochondrial morphology and/or function alterations are involved in stress-induced adaptive pathways, priming mitochondria for mitophagy or apoptosis induction. We have previously shown that the mitochondriotropic antioxidant AntiOxCIN₄ (100 μM; 48 h) presented significant cytoprotective effect without affecting the viability of human hepatoma-derived (HepG2) cells. Moreover, AntiOxCIN₄ (12.5 μM; 72 h) caused a mild increase of reactive oxygen species (ROS) levels without toxicity to primary human skin fibroblasts (PHSF). As Nrf2 is a master regulator of the oxidative stress response inducing antioxidant-encoding gene expression, we hypothesized that AntiOxCIN₄ could increase the resistance of human hepatoma-derived HepG2 to oxidative stress by Nrf2-dependent mechanisms, in a process mediated by mitochondrial ROS (mtROS). Here we showed that after an initial decrease in oxygen consumption paralleled by a moderate increase in superoxide anion levels, AntiOxCIN₄ led to a time-dependent Nrf2 translocation to the nucleus. This was followed later by a 1.5-fold increase in basal respiration and a 1.2-fold increase in extracellular acidification. AntiOxCIN₄ treatment enhanced mitochondrial quality by triggering the clearance of defective organelles by autophagy and/or mitophagy, coupled with increased mitochondrial biogenesis. AntiOxCIN₄ also up-regulated the cellular antioxidant defense system. AntiOxCIN₄ seems to have the ability to maintain hepatocyte redox homeostasis, regulating the electrophilic/nucleophilic tone, and preserve cellular physiological functions. The obtained data open a new avenue to explore the effects of AntiOxCIN₄ in the context of preserving hepatic mitochondrial function in disorders, such as NASH/NAFLD and type II diabetes.

Effects of methylglyoxal and pyridoxamine in rat brain mitochondria bioenergetics and oxidative status

Advanced glycation end products (AGEs) and methylglyoxal (MG), an important intermediate in AGEs synthesis, are thought to contribute to protein aging and to the pathogenesis of age-and diabetes-associated complications. This study was intended to investigate brain mitochondria bioenergetics and oxidative status of rats previously exposed to chronic treatment with MG and/or with pyridoxamine (PM), a glycation inhibitor. Brain mitochondrial fractions were obtained and several parameters were analyzed: respiratory chain [states 3 and 4 of respiration, respiratory control ratio (RCR), and ADP/O index] and phosphorylation system [transmembrane potential (ΔΨm), ADP-induced depolarization, repolarization lag phase, and ATP levels]; hydrogen peroxide (H2O2) production levels, mitochondrial aconitase activity, and malondialdehyde levels as well as non-enzymatic antioxidant defenses (vitamin E and glutathione levels) and enzymatic antioxidant defenses (glutathione disulfide reductase (GR), glutathione peroxidase (GPx), and manganese superoxide dismutase (MnSOD) activities). MG treatment induced a statistical significant decrease in RCR, aconitase and GR activities, and an increase in H2O2 production levels. The administration of PM did not counteract MG-induced effects and caused a significant decrease in ΔΨm. In mitochondria from control animals, PM caused an adaptive mechanism characterized by a decrease in aconitase and GR activities as well as an increase in both α-tocopherol levels and GPx and MnSOD activities. Altogether our results show that high levels of MG promote brain mitochondrial impairment and PM is not able to reverse MG-induced effects.

Rapeseed oil-rich diet alters hepatic mitochondrial membrane lipid composition and disrupts bioenergetics

Diet is directly related with physiological alterations occurring at a cell and subcellular level. However, the role of diet manipulation on mitochondrial physiology is still largely unexplored. Aiming at correlating diet with alterations of mitochondrial membrane composition and bioenergetics, Wistar-Han male rats were fed for 11, 22 and 33 days with a rapeseed oil-based diet and mitochondrial bioenergetics, and membrane composition were compared at each time point with a standard diet group. Considerable differences were noticed in mitochondrial membrane lipid composition, namely in terms of fatty acyl chains and relative proportions of phospholipid classes, the modified diet inducing a decrease in the saturated to unsaturated molar ratio and an increase in the phosphatidylcholine to phosphatidylethanolamine molar ratio. Mass spectrometry lipid analysis showed significant differences in the major species of cardiolipin, with an apparent increased incorporation of oleic acid as a result of exposure to the modified diet. Rats fed the modified diet during 22 days showed decreased hepatic mitochondrial state 3 respiration and were more susceptible to Ca(2+)-induced transition pore opening. Rapeseed oil-enriched diet also appeared to promote a decrease in hydroperoxide production by the respiratory chain, although a simultaneous decrease in vitamin E content was detected. In conclusion, our data indicate that the rapeseed oil diet causes negative alterations on hepatic mitochondrial bioenergetics, which may result from membrane remodeling. Such alterations may have an impact not only on energy supply to the cell, but also on drug-induced hepatic mitochondrial liabilities.

Insulin-induced recurrent hypoglycemia exacerbates diabetic brain mitochondrial dysfunction and oxidative imbalance

Intensive insulin therapy can prevent or slow the progression of long-term diabetes complications but, at the same time, it increases the risk for episodes of severe hypoglycemia. In our study, we used a protocol intended to mimic the levels of blood glucose that occur in type 1 diabetic patients under an intensive insulin therapy. Streptozotocin (STZ)-induced diabetic rats were treated subcutaneously with twice-daily insulin injections for 2weeks to induce hypoglycemic episodes. Brain cortical and hippocampal mitochondria were isolated and mitochondrial bioenergetics (respiratory chain and phosphorylation system) and oxidative status parameters (malondialdehyde (MDA) levels, mitochondrial aconitase activity and enzymatic and non-enzymatic antioxidant defenses) were analyzed. The protein levels of synaptophysin, a marker of synaptic integrity, and caspase 9 activity were also evaluated in cortical and hippocampal homogenates. Brain cortical mitochondria isolated from hyper- and recurrent hypoglycemic animals presented higher levels of MDA and α-tocopherol together with an increased glutathione disulfide reductase activity, lower manganese superoxide dismutase (MnSOD) activity and glutathione-to-glutathione disulfide (GSH/GSSG) ratio. No significant alterations were found in cortical mitochondrial respiratory chain and oxidative phosphorylation system. Hippocampal mitochondria from both experimental groups presented an impaired oxidative phosphorylation system characterized by a decreased mitochondrial energization potential and ATP levels and higher repolarization lag phase. In addition, higher MDA levels and decreased GSH/GSSG, α-tocopherol levels, and aconitase, glutathione peroxidase and MnSOD activities were observed in both groups of animals. Hippocampal mitochondria from recurrent hypoglycemic animals also showed an impairment of the respiratory chain characterized by a lower state 3 of respiration, respiratory control ratio and ADP/O index, and a higher state 4 of respiration. Additionally, a non-statistically significant decrease in synaptophysin protein levels was observed in cortical homogenates from recurrent hypoglycemic rats as well as in hippocampal homogenates from hyperglycemic and recurrent hypoglycemic rats. An increase in caspase 9 activity was also observed in hippocampal homogenates from hyperglycemic and recurrent hypoglycemic animals. Our results show that mitochondrial dysfunction induced by long-term hyperglycemic effects is exacerbated by recurrent hypoglycemia, which may compromise the function and integrity of brain cells.

Metabolic alterations induced by sucrose intake and Alzheimer's disease promote similar brain mitochondrial abnormalities

Evidence shows that diabetes increases the risk of developing Alzheimer's disease (AD). Many efforts have been done to elucidate the mechanisms linking diabetes and AD. To demonstrate that mitochondria may represent a functional link between both pathologies, we compared the effects of AD and sucrose-induced metabolic alterations on mouse brain mitochondrial bioenergetics and oxidative status. For this purpose, brain mitochondria were isolated from wild-type (WT), triple transgenic AD (3xTg-AD), and WT mice fed 20% sucrose-sweetened water for 7 months. Polarography, spectrophotometry, fluorimetry, high-performance liquid chromatography, and electron microscopy were used to evaluate mitochondrial function, oxidative status, and ultrastructure. Western blotting was performed to determine the AD pathogenic protein levels. Sucrose intake caused metabolic alterations like those found in type 2 diabetes. Mitochondria from 3xTg-AD and sucrose-treated WT mice presented a similar impairment of the respiratory chain and phosphorylation system, decreased capacity to accumulate calcium, ultrastructural abnormalities, and oxidative imbalance. Interestingly, sucrose-treated WT mice presented a significant increase in amyloid β protein levels, a hallmark of AD. These results show that in mice, the metabolic alterations associated to diabetes contribute to the development of AD-like pathologic features.

Vitamin E and neurological function

The clinical, neuropathological and electrophysiological evidence that vitamin E (alpha-tocopherol) is essential for normal neurological function will be reviewed. The possible reasons why neural tissues should be particularly affected by a deficiency of this fat-soluble vitamin and the mechanism(s) involved will be considered.

Vitamin C distribution and retention in the mouse brain

Vitamin C (VC) is a crucial antioxidant in the brain. To assess whether different brain regions vary in their sensitivity to oxidative stress induced by VC depletion, we used the gulonolactone oxidase (gulo) knockout mouse. This mouse, like humans, cannot synthesize VC and thus its tissue VC levels can be varied by dietary VC intake. Gulo knockout mice were fed drinking water containing standard (0.33g/L), low (0.033g/L) or zero (0g/L) VC supplementation levels. After 4weeks, mice were sacrificed and different brain regions removed for assay of VC and malondialdehyde, a marker of lipid peroxidation. Compared to age-matched wild-type controls, the cerebellum, olfactory bulbs and frontal cortex had the highest VC content, whereas the pons and spinal chord had the lowest. However, in mice that did not receive VC, area differences were no longer significant as all values trended towards zero. Malondialdehyde increased in the cortex as VC supplementation was decreased. The same changes were not observed in the cerebellum or pons, suggesting that cortex is more susceptible to oxidative damage from low VC. These results suggest enhanced susceptibility of the cortex to oxidative stress induced by low VC compared to other brain regions.

Doxorubicin increases the susceptibility of brain mitochondria to Ca(2+)-induced permeability transition and oxidative damage

This study was aimed at investigating the effects of subchronic administration of doxorubicin (DOX) on brain mitochondrial bioenergetics and oxidative status. Rats were treated with seven weekly injections of vehicle (sc, saline solution) or DOX (sc, 2 mg kg(-1)), and 1 week after the last administration of the drug the animals were sacrificed and brain mitochondrial fractions were obtained. Several parameters were analyzed: respiratory chain, phosphorylation system, induction of the permeability transition pore (PTP), mitochondrial aconitase activity, lipid peroxidation markers, and nonenzymatic antioxidant defenses. DOX treatment induced an increase in thiobarbituric acid-reactive substances and vitamin E levels and a decrease in reduced glutathione content and aconitase activity. Furthermore, DOX potentiated PTP induced by Ca2+. No statistical differences were observed in the other parameters analyzed. Altogether our results show that DOX treatment increases the susceptibility of brain mitochondria to Ca(2+)-induced PTP opening and oxidative stress, predisposing brain cells to degeneration and death.

Brain oxidative stress in a triple-transgenic mouse model of Alzheimer disease

Alzheimer disease (AD) is a neurodegenerative disease which is characterized by the presence of extracellular senile plaques mainly composed of amyloid-beta peptide (Abeta), intracellular neurofibrillary tangles, and selective synaptic and neuronal loss. AD brains revealed elevated levels of oxidative stress markers which have been implicated in Abeta-induced toxicity. In the present work we addressed the hypothesis that oxidative stress occurs early in the development of AD and evaluated the extension of the oxidative stress and the levels of antioxidants in an in vivo model of AD, the triple-transgenic mouse, which develops plaques, tangles, and cognitive impairments and thus mimics AD progression in humans. We have shown that in this model, levels of antioxidants, namely, reduced glutathione and vitamin E, are decreased and the extent of lipid peroxidation is increased. We have also observed increased activity of the antioxidant enzymes glutathione peroxidase and superoxide dismutase. These alterations are evident during the Abeta oligomerization period, before the appearance of Abeta plaques and neurofibrillary tangles, supporting the view that oxidative stress occurs early in the development of the disease.

Blood oxidative stress markers in non-alcoholic steatohepatitis and how it correlates with diet

OBJECTIVE

Non-alcoholic fatty liver disease is a common condition that can progress to endstage liver disease. The steatotic liver seems to be particularly susceptible to oxidative stress damage. The aim of this study was to evaluate the redox state in patients with non-alcoholic steatohepatitis (NASH) and its correlation with dietary intake.

MATERIAL AND METHODS

Plasma concentrations of 4-hydroxynonenal (4-HNE), 8-hydroxydeoxyguanosine (8-OHdG), reduced and oxidized glutathione (GSH and GSSG), vitamins A and E, total antioxidant status (TAS), glutathione peroxidase (GSH-Px) and reductase (GSH-Red) erythrocyte activities were compared between 43 NASH patients and 33 healthy controls. 4-HNE, GSH-Px, GSH-Red and TAS were evaluated by spectrophotometry, 8-OHdG by ELISA assay, GSH and GSSG by fluorimetric assay and vitamins A and E by high performance liquid chromatography. Dietary habits were also evaluated in these patients.

RESULTS

GSH levels (21.1 +/- 18.3 versus 33.1 +/- 22.2 microM, p = 0.01) and GSH/GSSG ratio (0.9 +/- 0.7 versus 1.5 +/- 0.8, p = 0.01) were lower and TAS (832 +/- 146 versus 630 +/-140 microM, p < 0.001) and vitamin E (47.1 +/- 14.9 versus 34.5 +/- 7.3 microM, p < 0.001) were higher in NASH patients, although there was no difference in GSH-Px and GSH-Red activities, 8-OHdG and 4-HNE levels between groups. After adjusting for total energy consumption, a negative correlation was found with total and saturated fat intake and GSH/GSSG ratio, and a positive correlation with carbohydrates, fiber, monounsaturated fatty acids (MUFA), polyunsaturated fatty acids (PUFA), specifically N-3 PUFA, and vitamins E, C, selenium and folate.

CONCLUSIONS

Our data suggest an impaired glutathione metabolism towards an oxidant status in NASH patients, correlating with a higher intake of saturated fat and a lower intake of carbohydrates. Plasmatic concentrations of oxidative stress cellular markers did not translate to hepatic oxidative damage.

Evidence for oxidative stress in tissues derived from succinate semialdehyde dehydrogenase-deficient mice

Animal models of inborn errors of metabolism are useful for investigating the pathogenesis associated with the corresponding human disease. Since the mechanisms involved in the pathophysiology of succinate semialdehyde dehydrogenase (SSADH) deficiency (Aldh5a1; OMIM 271980) are still not established, in the present study we evaluated the tissue antioxidant defences and lipid peroxidation in various cerebral structures (cortex, cerebellum, thalamus and hippocampus) and in the liver of SSADH-deficient mice. The parameters analysed were total radical-trapping antioxidant potential (TRAP) and glutathione (GSH) levels, the activities of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), as well as thiobarbituric acid-reactive substances (TBARS). We first observed that the tissue nonenzymatic antioxidant defences were significantly reduced in the SSADH-deficient animals, particularly in the liver (decreased TRAP and GSH) and in the cerebral cortex (decreased GSH), as compared to the wild-type mice. Furthermore, SOD activity was significantly increased in the liver and cerebellum, whereas the activity of CAT was significantly higher in the thalamus. In contrast, GPx activity was significantly diminished in the hippocampus. Finally, we observed that lipid peroxidation (TBARS levels) was markedly increased in the liver and cerebral cortex, reflecting a high lipid oxidative damage in these tissues. Our data showing an imbalance between tissue antioxidant defences and oxidative attack strongly indicate that oxidative stress is involved in the pathophysiology of SSADH deficiency in mice, and likely the corresponding human disorder.

Vitamin E, ascorbate, glutathione, glutathione disulfide, and enzymes of glutathione metabolism in cultures of chick astrocytes and neurons: evidence that astrocytes play an important role in antioxidative processes in the brain

GSH, GSSG, vitamin E, and ascorbate were measured in 14-day cultures of chick astrocytes and neurons and compared with levels in the forebrains of chick embryos of comparable age. Activities of enzymes involved in GSH metabolism were also measured. These included gamma-glutamylcysteine synthetase, GSH synthetase, gamma-glutamyl cyclotransferase, gamma-glutamyltranspeptidase, glutathione transferase (GST), GSH peroxidase, and GSSG reductase. The concentration of lipid-soluble vitamin E in the cultured neurons was found to be comparable with that in the forebrain. On the other hand, the concentration of vitamin E in the astrocytes was significantly greater in the cultured astrocytes than in the neurons, suggesting that the astrocytes are able to accumulate exogenous vitamin E more extensively than neurons. The concentrations of major fatty acids were higher in the cell membranes of cultured neurons than those in the astrocytes. Ascorbate was not detected in cultured cells although the chick forebrains contained appreciable levels of this antioxidant. GSH, total glutathione (i.e., GSH and GSSG), and GST activity were much higher in cultured astrocytes than in neurons. gamma-Glutamylcysteine synthetase activity was higher in the cultured astrocytes than in the cultured neurons. GSH reductase and GSH peroxidase activities were roughly comparable in cultured astrocytes and neurons. The high levels of GSH and GST in cultured astrocytes appears to reflect the situation in vivo. The data suggest that astrocytes are resistant to reactive oxygen species (and potentially toxic xenobiotics) and may play a protective role in the brain.(ABSTRACT TRUNCATED AT 250 WORDS)

Iron-dependent peroxidation of rat brain: a regional study

Iron has been shown to initiate a variety of free radical reactions in biological systems. The present study examined the in vitro susceptibility of homogenates prepared from different regions of rat brain to iron-induced peroxidation. Among the regions studied, basal thiobarbituric acid-reactive product (TBAR) formation is highest in the cerebellum and amygdala, intermediate in the cortex, hippocampus, and neostratium, and lowest in the hypothalamus, midbrain, and brainstem. In the presence of 200 microM FeCl3, there is a 20-25-fold increase in the net TBAR formation in all regions, with TBAR formation in the cerebellum and amygdala being significantly higher than in the midbrain and brainstem. Time-course and dose-response studies of iron-induced peroxidation showed that the cerebellum and amygdala are the most susceptible regions with respect to concentration of iron and duration of the incubation time, whereas the midbrain and brainstem are the least affected areas. Following low-speed (1,000 g) centrifugation of brain part homogenates, TBAR formation in the supernatant fractions is quite uniform across regions, while the pellet fractions give the same regional variations as the whole homogenates. TBAR formation in both fractions is increased 20-30-fold in the presence of 200 microM iron. Brain tissue TBAR formation induced by 200 microM iron is inhibited by the iron chelator desferrioxamine (IC50 = 600 microM), by Tris buffer pH = 8.0 (2.5 mM Tris gives 50% inhibition by trapping hydroxyl radicals), and by high concentrations of the cyclooxygenase inhibitor indomethacin (IC50 = 1.2 mM).

Effect of dietary vitamin E and selenium on susceptibility of brain regions to lipid peroxidation

The effect of dietary vitamin E and/or selenium (Se) supplementation (200 IU and/or 0.2 ppm, respectively) or deficiency for two months on lipid peroxidation in cerebrum, cerebellum, mid-brain, and brain stem of one-month-old male F344 rats was investigated. Dietary treatment had a minimal effect on weight gain of rats for the period tested. Plasma alpha-tocopherol (alpha-T) concentration and glutathione peroxidase (GSH-Px) activity were reflective of dietary treatments. Supplementation of diets with vitamin E and/or Se increased plasma alpha-T and/or GSH-Px activity, while diets devoid of these nutrients reduced them significantly. Increased GSH-Px activity in Se-supplemented rats was further enhanced by vitamin E supplementation. Differential concentrations of alpha-T among brain regions were affected by dietary vitamin E but not by Se. In vitro lipid peroxidation of brain homogenates was inhibited by dietary vitamin E supplementation and increased by deficiency. Addition of 0.25 mM ascorbic acid or 0.1 mM of Fe2+ to brain homogenates markedly increased in vitro lipid peroxidation. Ascorbic acid-induced lipid peroxidation was inversely correlated with dietary vitamin E and Se in cerebrum. In vitro Fe2+-addition induced the greatest stimulation of lipid peroxidation, with cerebellum and brain stem of vitamin E-deficient rats showing the highest response to Fe2+ challenge. These findings indicate that concentrations of alpha-T among the brain regions are different and can be altered by dietary vitamin E treatments, cerebellum and brain stem are more susceptible to in vitro challenge by peroxidative agents than other regions, and the degree of lipid peroxidation of brain regions is partially affected by dietary vitamin E but not by Se in the levels tested.

Studies on the neurobiology of vitamin E (alpha-tocopherol) and some other antioxidant systems in the rat

To understand why nervous tissue should be particularly affected by severe deficiency of vitamin E, the distribution of vitamin E (alpha-tocopherol) and some other antioxidant systems was investigated. The concentration of vitamin E and the activities of glutathione peroxidase and superoxide dismutase were determined in different regions of the nervous system in male Wistar rats. The cerebral cortex had the highest, and the cerebellum the lowest concentration of alpha-tocopherol (P less than 0.02). Activity of glutathione peroxidase tended to show an inverse relationship to the alpha-tocopherol concentration, whereas superoxide dismutase activity was evenly distributed through the nervous tissue. Vitamin E concentrations were also determined in spinal cord, sciatic and tibial nerves and in epineurial, myelin and non-myelin fractions of the sciatic nerve. Uptake of intravenously injected tritiated alpha-tocopherol was studied after 6 h and found to be greater in brain and peripheral nerve than cervical and thoracic regions of the spinal cord. Uptake of tocopherol varied along the sciatic and tibial nerve, being greatest where the sciatic nerve divided into tibial, sural and common peroneal nerves. This corresponded to an area of increased vasculature which was visualized by an angiographic technique using barium sulphate.

Changes in vitamin E concentration in red blood cells and plasma of patients with olivopontocerebellar ataxia within the Schut-Swier kindred

Many reports have documented the importance of vitamin E for the function of the nervous system, especially of the cerebellum. Therefore, we studied the concentrations of vitamin E in the blood plasma and red blood cells of patients with a hereditary form of olivopontocerebellar ataxia. The concentrations of alpha tocopherol (the principal biologically-active form of vitamin E) in the plasma and red cells of the ataxic subjects were significantly lower than those of unaffected, close relatives as well as unrelated control subjects. Total lipids, cholesterol, triglycerides and lipoproteins in the serum of the ataxia group were all within normal range. The results suggest that this specific type of familial ataxia is associated with a rare and isolated abnormality in vitamin E and/or antioxidant metabolism. The vast majority of previous reports of lower blood concentrations or deficiency of vitamin E in children or adults were also associated with deficits in the absorption of lipids or abnormalities in serum lipids and lipoproteins.

Influence of dietary vitamin E, selenium and age on regional distribution of alpha-tocopherol in the rat brain

Concentrations of alpha-tocopherol (alpha-T) in plasma, cerebrum, cerebellum, midbrain and brain stem and activity of selenium (Se)-dependent glutathione peroxidase (GSH-Px) in plasma were measured in 1- and 15-month-old male F344 rats fed diets containing vitamin E (E, IU/kg) and Se (ppm) in the following combinations: 30 E, 0.1 Se (control diet, minimum requirements); 200 E, 0.2 Se; 0.0 E, 0.2 Se; 200 E, 0.0 Se; 0.0 E, 0.0 Se for 8 or 20 weeks. alpha-T and GSH-Px levels in plasma were reflective of dietary treatment in young rats in which an interaction of the two nutrients was noted. A longer period of dietary vitamin E deficiency was necessary to deplete plasma alpha-T and depress GSH-Px activity significantly in the old rats. Among the brain regions of all ages, cerebrum and midbrain had the highest concentrations of alpha-T while cerebellum showed the lowest. However, cerebellum of young rats and cerebellum and brain stem of old rats had a greater alpha-T accumulation with doubly supplemented diets, whereas only cerebellum of young and old rats showed a marked increase of alpha-T with vitamin E supplementation. In old rats, vitamin E deficiency resulted in greater depletion of alpha-T in cerebellum and brain stem than cerebrum and midbrain regions. Se deficiency in brain stem of young and old rats significantly decreased alpha-T accumulation by vitamin E supplementation. Se supplementation marginally alleviates vitamin E depletion in brain.(ABSTRACT TRUNCATED AT 250 WORDS)

Vitamin E concentrations in different regions of the spinal cord and sciatic nerve of the rat

Since the spinal cord and peripheral nerves are vulnerable to the effects of vitamin E deficiency, vitamin E concentrations in various discrete regions of these parts of the nervous system of the rat were determined. Furthermore, as acrylamide toxicity and vitamin E deficiency share some neuropathological features, tissue vitamin E concentrations in acrylamide-treated rats were also studied. Male Sprague Dawley rats (200 to 250 g body weight) were fed normal rat chow with or without 0.03% acrylamide in their drinking water. After 24 days, the animals were sacrificed and the tissues assayed for vitamin E by a liquid chromatographic method. Vitamin E concentrations decreased from cerebral cortex to spinal cord with no concentration gradients between different levels of the spinal cord. Sciatic nerve concentration of alpha tocopherol was as high as that of cerebral cortex, and the former also contained measurable amounts of gamma tocopherol. Vitamin E concentrations in the majority of nervous tissues samples remained unchanged with acrylamide treatment.

Postischemic cerebral lipid peroxidation in vitro: modification by dietary vitamin E

Using an in vitro system, we studied the effect of postischemic reoxygenation on cerebral lipid peroxidation in relation to the dietary intake of vitamin E (VE) in rats. Homogenates prepared from VE-deficient, -normal, and -supplemented brains, which were previously rendered ischemic for 30 min by decapitation, were incubated under air or nitrogen gas for 60 min. The extent of peroxidation in brain tissue was estimated by a thiobarbituric acid (TBA) test and by diene conjugation in total lipid extracts. The brain levels of alpha-tocopherol and of total and free fatty acids (FAs) were also determined. Aerobic incubation increased TBA reactants in all dietary groups; the effect was largest in the VE-deficient group, intermediate in the VE-normal group, and smallest in the VE-supplemented group. In contrast, nitrogen incubation did not alter the basal levels of TBA reactants except for a small rise associated with VE deficiency. Conjugated dienes changed in parallel with TBA reactants. alpha-Tocopherol decreased after aerobic incubation and also, to a lesser degree, after nitrogen incubation in each dietary group. Only in the reoxygenated samples of the VE-deficient group was there a significant fall in total polyunsaturated FAs. The levels of free FAs continuously increased throughout ischemia and subsequent incubation. However, the level of free polyunsaturated FAs was similar after aerobic and nitrogen incubation in each dietary group, and was not affected by VE. Thus, cerebral reoxygenation after ischemia propagates peroxidative reactions within esterified polyunsaturated FAs. The modification by VE of reoxygenation-induced lipid peroxidation suggests free radical mediation.

Concentrations of vitamin E in various neuroanatomical regions and subcellular fractions, and the uptake of vitamin E by specific areas, of rat brain

Vitamin E concentrations were determined by high-performance liquid chromatography in different anatomical regions of the brain from 3-month-old Fischer 344 rats. Gray matter from cerebellum and cervical spinal cord contained the lowest concentrations, while gray matter from the frontal cortex and thalamus had the highest concentrations of vitamin E. Radioactive alpha-tocopherol injected intravenously into the rat was readily taken up by brain although the level of uptake was very low compared with the liver. The ratios of brain-to-serum radioactivities ranged from 0.011 to 0.016 depending upon the brain region. Cerebellar gray matter is characterized by a low concentration of unlabeled alpha-tocopherol and a high level of uptake of radioactive alpha-tocopherol and thus is particularly active in the metabolism of vitamin E. Concentrations of unlabeled alpha-tocopherol were highest in microsomal and mitochondrial fractions and were the lowest in cytosol and nuclear fractions.

Vitamin E concentrations in the brains and some selected peripheral tissues of selenium-deficient and vitamin E-deficient mice

Weanling male CD-l mice were fed control, vitamin E-deficient or selenium-deficient diets for periods of 12 to 20 weeks. alpha-Tocopherol concentrations in plasma, liver, and testes, as well as in three specific areas in the brain (cerebral hemisphere, cerebellum, and medulla plus pons) were determined by high performance liquid chromatography. Significant concentrations of alpha-tocopherol were found in all brain samples from vitamin E-deficient animals long after the peripheral tissues were depleted, indicating that brain is more resistant to vitamin E deficiency than peripheral tissues. Cerebellar concentrations of alpha-tocopherol were consistently lower than those of cerebral hemisphere and medulla-pons. Furthermore, the cerebellar alpha-tocopherol concentration sustained a larger decline than the other two brain areas within 6 weeks of vitamin E deficiency treatment. These and other data suggest that cerebellum may be more susceptible to damage from vitamin E deficiency than other parts of the brain. Selenium deficiency did not affect brain alpha-tocopherol concentrations during the 12 weeks of the study.