Effect of dietary vitamin E on lipofuscin accumulation with age in the rat brain

Potential innovation against Alzheimer's disorder: a tricomponent combination of natural antioxidants (vitamin E, quercetin, and basil oil) and the development of its intranasal delivery

Alzheimer's disorder (AD) is very difficult to manage and treat. The complexity of the brain, the blood-brain barrier influencing a multitude of parameters/biomarkers, as well as numerous other factors involved often contribute to the decline in the chances of treatment success. Development of the new drug moiety also takes time, being necessary to consider both its toxicity and related issues. As a strategic plan, a combined strategy is being developed and considered to address AD pathology using several approaches. A combination of vitamin E, quercetin, and basil oil in a nano-based formulation is designed to be administered nasally. The antioxidant present in these natural-based products helps to treat and alleviate AD if a synergistic approach is considered. The three active substances mentioned above are well known for the treatment of neurodegenerative disorders. The nanoformulation helps the co-delivery of the drug moiety to the brain through the intranasal route. In this review, a correlation and use of vitamin E, quercetin, and basil oil in a nano-based formulation is described as an effective way to treat AD. The intranasal administration of drugs is a promising approach for the treatment of neurodegenerative and mental disorders, as this route is non-invasive, enhances the bioavailability, allows a drug dose reduction, bypasses the blood-brain barrier, and reduces the systemic undesired effect. The use of natural products is generally considered to be just as safe; therefore, by using this combined approach, the level of toxicity can be minimized.

Vitamin E-gene interactions in aging and inflammatory age-related diseases: implications for treatment. A systematic review

Aging is a complex biological phenomenon in which the deficiency of the nutritional state combined with the presence of chronic inflammation and oxidative stress contribute to the development of many age-related diseases. Under this profile, the free radicals produced by the oxidative stress lead to a damage of DNA, lipids and proteins with subsequent altered cellular homeostasis and integrity. In young-adult age, the cell has a complex efficient system to maintain a proper balance between the levels of free radicals and antioxidants ensuring the integrity of cellular components. In contrast, in old age this balance is poorly efficient compromising cellular homeostasis. Supplementation with Vitamin E can restore the balance and protect against the deteriorating effects of oxidative stress, progression of degenerative diseases, and aging. Experiments in cell cultures and in animals have clearly shown that Vitamin E has a pivotal role as antioxidant agent against the lipid peroxidation on cell membranes preserving the tissue cells from the oxidative damage. Such a role has been well documented in immune, endothelial, and brain cells from old animals describing how the Vitamin E works both at cytoplasmatic and nuclear levels with an influence on many genes related to the inflammatory/immune response. All these findings have supported a lot of clinical trials in old humans and in inflammatory age-related diseases with however contradictory and inconsistent results and even indicating a dangerous role of Vitamin E able to affect mortality. Various factors can contribute to all the discrepancies. Among them, the doses and the various isoforms of Vitamin E family (α,β,γ,δ tocopherols and the corresponding tocotrienols) used in different trials. However, the more plausible gap is the poor consideration of the Vitamin E-gene interactions that may open new roadmaps for a correct and personalized Vitamin E supplementation in aging and age-related diseases with satisfactory results in order to reach healthy aging and longevity. In this review, this peculiar nutrigenomic and/or nutrigenetic aspect is reported and discussed at the light of specific polymorphisms affecting the Vitamin E bioactivity.

Autofluorescent cells in rat brain can be convincing impostors in green fluorescent reporter studies

Cell transplant and gene therapies are promising approaches to many disorders of the nervous system. In studies involving cell transplants to the brain or nervous system, expression of green fluorescent protein (GFP) is commonly used to label cells, allowing their identification and histological assessment even after long post-operative survival times. Techniques employing viral tracing or reporter genes also commonly use GFP to label cells. Here, we document the presence of a subpopulation of green autofluorescent cells in the cortex and hippocampus of formaldehyde fixed, cryosectioned rat brains aged 3-9 months. Using standard microscopic fluorescence imaging techniques, we acquired clear images of green autofluorescent cells, complete with extensive processes, which appear to be well integrated into the host tissue. Treatment of brain sections with sodium borohydride followed by cupric sulfate in ammonium acetate buffer reduced background and cellular autofluorescence throughout sections but, especially in hippocampus, did not eliminate considerable green fluorescence in a subset of neurons. This autofluorescence was weak and would therefore pose a problem only when cells weakly express GFP or when few labeled cells survive. We suggest that investigators be aware of the potential for false positives, especially if the cells expressing GFP are expected to migrate widely from the transplant site. Parallel sections from naïve brains should regularly be processed and imaged alongside experimental brain sections, and anti-GFP immunohistochemistry should be performed to ensure that true GFP+ signals are imaged instead of endogenous autofluorescent neurons.

Oxidative stress in erythrocytes: a study on the effect of antioxidant mixtures during intermittent exposures to high altitude

The aim of our study was to compare and assess the effectiveness of antioxidant mixtures on the erythrocytes (RBC) of adult male albino rats (Wister) subjected to simulated intermittent high altitudes--5,100 m (AL(1)) and 6,700 m (AL(2))--to induce oxidative stress (OS). To achieve our objective, we pre-supplemented four sets of animals with different antioxidant mixtures [vitamin E (vit.E; 50 IU/kg BW), vitamin C (vit.C; 400 mg/kg) and L: -carnitine (400 mg/kg)] in different combinations [M1 (vit.E+vit.C), M2 (vit.C+carnitine), M3 (vit.E+carnitine) and M4 (vit.C+vit.E+carnitine)] for 30 days prior to as well during exposure to intermittent hypobaric hypoxia (IHH). Membrane instability, in terms of osmotic fragility and hemolysis, decreased in RBCs of supplemented animals. There was a significant increase in the activity of glutathione peroxidase in the RBCs of supplemented animals. We confirmed OS imposed by IHH with assays relating to lipid [thiobarbituric acid reactive substances (TBARS) and lipofuscin (LF)] and protein (carbonyl, PrC) oxidation, and found a positive correlation between PrC and hemolysis, with a decrease in both upon supplementation with M3 and M4 mixtures. Fluorescence microscopic observation showed a maximum decrease in the LF content in rats administered M4 and M1 compared to those on M2 and M3 mixtures at both altitudes. We suggest that multiple antioxidant fortifications are effective in overcoming increased OS experienced by RBCs at high altitudes.

Vitamin E: An overview of major research directions

During the last 90 years since the discovery of vitamin E, research has focused on different properties of this molecule, the focus often depending on the specific techniques and scientific knowledge present at each time. Originally discovered as a dietary factor essential for reproduction in rats, vitamin E has revealed in the meantime many more important molecular properties, such as the scavenging of reactive oxygen and nitrogen species with consequent prevention of oxidative damage associated with many diseases, or the modulation of signal transduction and gene expression in antioxidant and non-antioxidant manners. Research over the last 30 years has also resolved the biosynthesis and occurrence of vitamin E in plants, the proteins involved in the cellular uptake, tissue distribution and metabolism, and defined a congenital recessive neurological disease, ataxia with vitamin E deficiency (AVED), characterized by impaired enrichment of alpha-tocopherol in plasma as a result of mutations in the liver alpha-tocopherol transfer gene. This review is giving a brief introduction about vitamin E by following the major research directions since its discovery with a historical perspective.

Modification by vitamin E and exercise of oxidative stress in regions of aging rat brain: Studies on superoxide dismutase isoenzymes and protein oxidation status

This study was aimed at determining the effect of exercise and vitamin E on age-associated changes in the superoxide dismutase (SOD), lipid (LPO) and protein oxidations (PO) in the cerebral cortex (CC), cerebellum (CB) and hippocampus (HC) of rat brain. For this, male Wistar albino rats of 4- (adult), 12- (middle-age) and 18-month (old) of age were orally supplemented with vitamin E and swim trained at 3% intensity for 30 min/day, 5 days/week, and for a period of 30 days. Reduced total SOD was evident with age in the CC while it was highest in the HC of old rats. Vitamin E elevated SOD in the old trainees. Mn-SOD increased in the middle-age and old trainees and Cu Zn-SOD increased in the supplemented and trained adults. Age-related and region-specific increase in protein carbonyl (PrC) content with decreased sulphydryl (P-SH) was seen. Vitamin E reduced PrC and advanced oxidation of protein products (AOPP) in all ages, and appreciably in the HC and CB. Our study emphasizes a correlation between mitochondrial H(2)O(2) generation, Mn-SOD activity and MDA level, and reveals in part an age-related increase in lipid peroxidation and protein oxidation, and that may occur under conditions such as vitamin E deficiency.

Biological markers in CSF and blood for axonal degeneration in multiple sclerosis

Biomarkers in body fluids could help to predict and monitor neurological decline in people with multiple sclerosis (MS). We discuss markers for axonal damage in body fluids in people with MS. The most promising axonal marker for discriminating patients with MS from those with other neurological diseases is the neurofilament light chain in CSF. Antibodies against the heavy-chain isoform are associated with disease progression. Other studies have shown altered CSF concentrations of tau proteins, actin, tubulin, and 14-3-3 protein. Interestingly, the concentration of 24S-hydroxycholesterol was decreased in serum of patients with MS. No clear changes have been shown for the markers apolipoprotein E and neurospecific enolase. We describe three types of markers for axonal damage: markers that reflect processes in the CNS, those that reflect extraneural processes, and those that reflect whole-body changes. These concepts may be helpful for biomarker research in various neurodegenerative diseases.

Tocopherol (vitamin E) in Alzheimer's disease and other neurodegenerative disorders

In this article, we review the evidence that tocopherol (vitamin E) may have a role to play in the prevention and treatment of Alzheimer's disease and other neurological diseases. The theoretical rationale for the effectiveness of tocopherol as treatment and/or prevention of Alzheimer's disease is based on its antioxidant properties. Results from animal and in vitro studies provide evidence to support use of tocopherol for prevention and treatment of degenerative neurological diseases. Furthermore, several, but not all, epidemiological, cross-sectional, prospective studies indicate that tocopherol may have protective effects in Alzheimer's disease, although dietary and supplemental forms of the vitamin may differ in their efficacy. Mixed results have been obtained from clinical trials. Evidence of the use of tocopherol as a protective measure or as therapy in neurological diseases other than Alzheimer's disease is less compelling. To date, there are no clear-cut answers as to whether tocopherol is worth prescribing, but current clinical practice favours its use in the treatment of Alzheimer's disease.

Phospholipid transfer protein (PLTP) deficiency reduces brain vitamin E content and increases anxiety in mice

Vitamin E supplementation constitutes a promising strategy in the prevention of neurodegenerative diseases. Here, we show that a phospholipid transfer protein (PLTP) is widely expressed in the brain where it appears to function as a transfer factor for alpha-tocopherol, the main isomer of vitamin E. PLTP deficiency results in significant depletion of brain alpha-tocopherol in both homozygous (-30.1%, P<0.0002) and heterozygous (-18.0%, P<0.05) PLTP knocked-out mice. Alpha-tocopherol depletion in PLTP-deficient homozygotes is associated with the elevation of lipofuscin (+25% and +450% increases in cortex and substantia nigra, respectively), cholesterol oxides (+54.5%, P<0.05), and cellular peroxides (+32.3%, P<0.01) in the brain. Complete PLTP deficiency in homozygotes is accompanied by increased anxiety as shown by fewer entries (8.3% vs. 44.4% in controls, P<0.01) and less time spent (1.7% vs. 41.3% in controls, P<0.05) in the open arms of an elevated plus-maze, in the absence of locomotor deterioration. Thus, the vitamin E transfer activity of PLTP appears to be a key process in preventing oxidative damage in the brain, and PLTP-deficient mice could be a new model of the contribution of oxidative brain injury in the etiology of neurodegenerative diseases.

Regional responses in antioxidant system to exercise training and dietary Vitamin E in aging rat brain

We have evaluated the effect of exercise, Vitamin E and a combination of both on the antioxidant enzymes (AOEs)-superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT) along with the products of lipid peroxidation (LP)-malondialdehyde (MDA) and lipofuscin-like auto fluorescent substances (LF-like AFS) in discrete brain regions of rats of 4 (young adults), 8 (old adults), 12 (middle-age) and 22 months (mos) old of age. Hippocampus (HC) showed greater increase in GSH-Px activity than cerebral cortex (CC) to exercise and Vitamin E and was irrespective of the age. A combination of both was effective in the CC of all age groups but not in the supplemented sedentary of 12- and 22-mo-olds. CAT activity increased significantly in the HC of supplemented and trained rats but not in the combination group of any age. SOD increased in both the regions of supplemented trainees. However, old were more benefited in terms of maximal elevation in the HC. Vitamin E reduced MDA content in both regions of adult. LF-like AFS decreased significantly in supplemented sedentary and trainees of all ages. Our results demonstrate that an age-related deficit in AOEs in the CC and HC can be overcome through Vitamin E plus exercise, and further suggests the rationale for looking at these markers of oxidative stress in several age-related neuronal diseases.

Dietary factors in lipofuscinogenesis and ceroidogenesis

The presence of ceroid pigments in human and animal tissues is associated with numerous pathological conditions in which the main pathogenic factor is the primary or secondary deficiency of vitamin E or imbalances between anti- and pro-oxidants. That oxidative stress, particularly through its consequent lipid peroxidation, plays a capital role in the genesis of ceroid pigments, is supported by numerous in vitro and in vivo studies. Discussed in this presentation are two examples of oxidative stress on ceroidogenesis, namely the in vivo rat model of dietary hepatic necrosis, and the in vitro formation of ceroid pigments by the aerobic incubation of unsaturated fat and blood cells. Although it is widely believed that the progressive accumulation of lipofuscin is also a marker of oxidative stress, and that this pigment can be modulated by the dietary anti- and pro-oxidant factors, the evidence for these related notions is highly questionable. Some years ago, this controversial problem was reexplored in our laboratories by a series of studies in Wistar male rats, and the results indicated that neither the type of dietary fat, nor the pharmacological amounts of vitamin E significantly influenced the amounts of lipofuscin in cerebral neurons, cerebellar Purkinje cells, hepatocytes or cardiac myocytes. It was also found that the indices of lipid peroxidation determined in this study (production of malonaldehyde, and detection of conjugated dienes) did not correlate with the progressive accumulation of lipofuscin with age. All these results strongly suggest that the presence and cellular accumulation of lipofuscin can hardly be considered a marker of oxidative stress.

d-MDMA during vitamin E deficiency: effects on dopaminergic neurotoxicity and hepatotoxicity

The mechanism of 3,4-methylenedioxymethamphetamine (d-MDMA)-induced neurotoxicity may involve formation of toxic radical species. Endogenous defenses against toxic radical species include tissue stores of vitamin E, and thiols. We examined whether vitamin E deficiency could alter d-MDMA-induced neurotoxicity by administration of the drug to animals with diet induced vitamin E deficiency. Brain vitamin E levels in deficient mice were reduced 75% compared to sufficient animals. Animals received d-MDMA 5 or 10 mg/kg or saline (delivered every 2 hx4, s.c.). Diet slightly altered d-MDMA-induced temperature modulation. In brain, MDMA treatment reduced vitamin E, total antioxidant reserve and protein thiols 72 h after the first dose. In liver, MDMA treatment reduced glutathione and total antioxidant reserve at the same time point. The vitamin E-deficient group, treated with the low dose of d-MDMA, exhibited neurotoxic responses, including reduced striatal dopamine (47%) and elevated GFAP protein (3-fold): while the sufficient diet group was not altered. The higher d-MDMA dose caused neurotoxic responses in both diet groups. Liver toxicity was determined by histopathologic examination. d-MDMA caused hepatic necrosis that was more severe in vitamin E deficient than sufficient mice. These data indicate that (1) d-MDMA administration reduces antioxidant measures at a time coincident with d-MDMA-induced neuronal damage and (2) vitamin E deficiency increases susceptibility to d-MDMA-induced neurotoxicity and hepatic necrosis.

Pigments in aging: an overview

Although during the normal aging process there are numerous pigmentary changes, the best recognized are those of melanin and lipofuscin. Melanin may increase (e.g., age spots, senile lentigo, or melanosis coli) or decrease (e.g., graying of hair or ocular melanin) with age, while lipofuscin (also called age pigment) always increases with age. In fact, the time-dependent accumulation of lipofuscin in lysosomes of postmitotic cells and some stable cells is the most consistent and phylogenetically constant morphologic change of aging. This pigment displays a typical autofluorescence (Ex: approximately 440; Em: approximately 600 nm), sudanophilia, argyrophilia, PAS positiveness, and acid fastness. Advances on its biogenesis, composition, evolution, and lysosomal degradation have been hampered by the persistent confusion between lipofuscin and the large family of ceroid pigments found in a variety of pathological conditions, as evidenced by the frequent use of the hybrid term lipofuscin/ceroid by investigators mainly working with in vitro systems of disputable relevance to in vivo lipofuscinogenesis. While lipofuscin and ceroid pigments may share some of their physicochemical properties at one moment or another in their evolutions, these pigments have different tissue distribution, rates of accumulation, origin of their precursors, and lectin binding affinities. Although it is widely believed that lipofuscin is a marker of oxidative stress, and that it can be, therefore, modified by antioxidants and prooxidants, these assumptions are mainly based on in vitro experiments and are not generally supported by in vivo studies. Another common misconception is the belief that lipofuscin can be extracted from tissues by lipid solvents and measured spectrofluorometrically. These and other disturbing problems are reviewed and discussed in this presentation.

A nucleoside-nucleotide mixture may reduce memory deterioration in old senescence-accelerated mice

We investigated the effects of a mixture of dietary nucleosides and nucleotides (NS + NT) on memory in 1- and 7-mo-old senescence-accelerated mice (SAM). Memory retention was studied with passive avoidance (step-through) and active avoidance (shuttle) tests. For 14 wk, mice in the control groups were fed a 20 g of casein/100 g diet, whereas the NS + NT groups were fed this diet supplemented with a 0.5 g of NS + NT mixture/100 g. All mice were killed at wk 14, and we studied the brain histopathology. Lipofuscin, monovacuoles and multiple vacuoles of various brain regions were measured. Body weight, food intake and ambulatory activity did not differ between the control and NS + NT groups. In old mice, the time of passive avoidance was significantly higher in the NS + NT group than in the control group at d 1 and 7 (P: < 0.05). However, such an effect of NS + NT was not observed in young mice. In the active avoidance test, the incidence of successful avoidance in old mice was higher in the NS + NT group than in the control group at d 1 and 2 (P: < 0.05). The percentages of specific brain cells containing lipofuscin were lower in NS + NT groups than in the control groups in both young and old mice (P: < 0.05). The number of monovacuoles and multiple vacuoles in specific brain regions tended to be lower (P: = 0.1-0.25) in NS + NT than in control groups, with significant differences in the microvacuoles of the middle cortex of young mice and in the multiple vacuoles in the hind cortex of old mice (P: < 0. 05). These results suggest that increased dietary NS + NT may be associated with decreases in the age-induced deterioration of brain morphology and certain memory tasks.

Formation of lipofuscin-like autofluorescent materials in NG108-15 cells: involvement of lysosomal protein degradation

We found that neuroblastoma x glioma hybrid NG108-15 cells accumulated lipofuscin-like autofluorescent materials during neuronal differentiation in culture in a medium containing 1% fetal calf serum, 1 mM dibutyryl cyclic AMP and 1 mM theophylline. The emission maximum of the lipofuscin-like autofluorescent materials was between 500 and 550 nm. Granules positive to acid phosphatase and periodic-acid Schiff were increased, as were the autofluorescent granules in NG108-15 cells. Thiolprotease inhibitors, N-(L-3-trans-carboxyoxirane-2-carbonyl)-L-leucine-4-aminobutyla mide (E-64) and acetyl-Leu-Leu-Arg (leupeptin), markedly accelerated the accumulation of the lipofuscin-like autofluorescent materials in NG108-15 cells. On the other hand, activities of lysosomal thiolproteases, cathepsin B, C and L, were increased during neuronal differentiation. Protein content in the cells was gradually increased with the neuronal differentiation, and the rise was significantly accelerated when proteolysis was inhibited by E-64. These results suggest that the lipofuscin-like autofluorescent materials contain peptidic substances as a component, and indicate that the increase in hydrolytic activities of thiolproteases during neuronal differentiation is not enough for the hydrolysis of peptidic substrates, resulting in the accumulation of autofluorescent materials in NG108-15 cells.

Vitamin E and Alzheimer disease: the basis for additional clinical trials

Many lines of evidence suggest that oxidative stress is important in the pathogenesis of Alzheimer disease. In particular, beta-amyloid, which is found abundantly in the brains of Alzheimer disease patients, is toxic in neuronal cell cultures through a mechanism involving free radicals. Vitamin E prevents the oxidative damage induced by beta-amyloid in cell culture and delays memory deficits in animal models. A placebo-controlled, clinical trial of vitamin E in patients with moderately advanced Alzheimer disease was conducted by the Alzheimer's Disease Cooperative Study. Subjects in the vitamin E group were treated with 2000 IU (1342 alpha-tocopherol equivalents) vitamin E/d. The results indicated that vitamin E may slow functional deterioration leading to nursing home placement. A new clinical trial is planned that will examine whether vitamin E can delay or prevent a clinical diagnosis of Alzheimer disease in elderly persons with mild cognitive impairment.

The preventative role of antioxidants (selegiline and vitamin E) in a rat model of tardive dyskinesia

BACKGROUND

We examined the potential protective effects of two potent antioxidants, selegiline and vitamin E, in a rodent model of tardive dyskinesia (TD), viz. neuroleptic-induced spontaneous orofacial movements.

METHODS

Rats were treated with fortnightly injections of fluphenazine decanoate for 12 weeks, and examined at baseline and at fortnightly intervals for vacuous chewing movements, mouth tremors and tongue protrusions.

RESULTS

The administration of fluphenazine led to a progressive increase of all three types of orofacial movements. In the first study, the impact of the concomitant administration of selegiline on orofacial movements was examined. Selegiline led to a reduction in orofacial movements in neuroleptic-treated rats to the level of control rats not being administered a neuroleptic drug. In the second study, rats were fed diets either high or low in their vitamin E content. High and low vitamin E diets did not significantly affect neuroleptic-induced orofacial movements.

CONCLUSIONS

Our studies provide some support for the hypothesis that oxidative injury may play a role in the genesis of neuroleptic-induced movement disorder, and prompt further examination of this hypothesis in both animals and humans.

Immunohistochemical detection of dityrosine in lipofuscin pigments in the aged human brain

Lipofuscin is a yellowish brown fluorescent pigment which is sequestered within cytoplasmic granules during aging. To examine the contribution of protein oxidation to lipofuscin accumulation, we performed immunohistochemical detection of dityrosine, which is considered one of the specific markers for protein oxidation, in lipofuscin in the aged human brain using an antibody specific to dityrosine. By characterization using competitive enzyme-linked immunosorbent assay, the specificity of the antibody to dityrosine was confirmed. None of the other tyrosine-related compounds such as L-tyrosine, 3-nitrotyrosine, 3-chlorotyrosine, or 3,4-dihydroxyphenylalanine cross-reacted with the antibody. The anti-dityrosine antibody reacted with lipofuscin granules in the pyramidal neurons of the aged human brain. The results suggest that protein oxidation by free radicals and/or peroxidases may play an important role in lipofuscin accumulation.

Dietary vitamin E levels affect outcome of permanent focal cerebral ischemia in rats

BACKGROUND AND PURPOSE

A supraphysiological amount of vitamin E in the standard diet of laboratory animals may provide partial protection against cerebral ischemic damage in stroke models. The aim of the present study was to test the effect of dietary vitamin E on infarct volume in rats subjected to permanent focal cerebral ischemia.

METHODS

Male Wistar rats were raised on a vitamin E-deficient diet (n=10) or a control diet containing 62.7 mg vitamin E/kg (n=11) for 13 to 16 weeks, from the age of 3 weeks. The left middle cerebral artery (MCA) was permanently occluded by means of an intraluminal silicone-coated 3-0 suture. Blood flow in the left MCA territory was measured before and after occlusion with laser Doppler flowmetry. The area of infarction was measured in hematoxylin-eosin-stained brain sections by means of an image analysis system. The investigator was not aware of the vitamin E status of the rats.

RESULTS

Blood flow in the left MCA territory in the second half hour after occlusion was 43+/-17% and 42+/-17% (mean+/-SD) of the baseline value in control and vitamin E-deficient rats, respectively. The mean infarct volume, measured after 48 hours of survival, was 61+/-19 mm3 in control rats and 137+/-76 mm3 in vitamin E-deficient rats (P=0.037).

CONCLUSIONS

After permanent focal cerebral ischemia, the infarct is larger in vitamin E-deficient rats than in rats raised on a diet with the usual, supraphysiological amount of vitamin E. This may have consequences for cerebral ischemia studies with experimental animals.

The effect of altered selenium and vitamin E nutritional status on learning and memory of third-generation rats

It has been proposed that selenium (Se) and Vitamin E (Vit E) are involved synergistically in protection of cell membrane lipids from peroxidation. However, little is known about the effect of both deficiencies of Se and Vit E and toxic status of those antioxidants on the peroxidation potentiality of the brain. We aimed to study the effects of both Se and Vit E inadequate diet and Se rich diet on the learning and memory processes of third-generation young rats. Their ancestors were also fed by the same diets starting from their births. To test the learning and memory, the rats aged 60 days were trained by using automated two ways active avoidance shuttle box. The acquisition tests were terminated with training the rat from each group to be 25 trials per day during three days. Ten days after the last acquisition test, the retention test was performed and the acquisition of the conditioned avoidance responses (CAR) of the rats were evaluated. It is demonstrated that the CAR of all rats from three groups showed a significant increase in three consecutive days while the differences observed in CAR of same sessions was not significantly different among three groups. The memory process of these young rats also was not affected significantly by two types of diets. Under the light of our results one can suggest that, in the case of alterations in antioxidant defense status, the learning and the memory mechanisms seems to be not affected. Further researches are needed to be able to explain the possible role of oxidative stress on the mechanisms of learning and memory.

Can antioxidant supplementation slow the aging process?

The oxidative stress theory of aging is well supported by accumulated evidence from various aging intervention studies. Early antioxidant supplementation studies indicate life span extensions by antioxidant feeding in various experimental organisms. Data collected under tightly controlled conditions show that the feeding of 2-mercaptoethanol (0.25%) effectively prolonged both the median and maximum life spans of mice. Evidence has been obtained showing dietary vitamin E to protect against oxidative damage to DNA in human lymphocytes and white blood cells. Other clear evidence of vitamin E's protective effect has been seen in its suppressive action of LDL oxidation both in vitro and in vivo. New evidence on the physiological roles of antioxidants, in addition to their well-known role as free radical scavengers, is emerging from recent research. For instance, the beneficial effect of vitamin E in improving glucose transport and the insulin sensitivity and its putative role as a regulator of cell proliferation should open new research dimensions. This presentation will review some of the anti-aging aspects of dietary antioxidant supplementation, as well as the potential problems of its long-term administration that stem from our lack of knowledge about free radical metabolism and the regulation of endogenous defense mechanisms.

Immunohistochemical localization of advanced glycation end products, pentosidine, and carboxymethyllysine in lipofuscin pigments of Alzheimer's disease and aged neurons

Lipofuscins are intracellular fluorescent pigments accumulating in the central nervous system (CNS) with aging and degenerative processes such as Alzheimer's disease (AD). Although they are thought to be lipid peroxidation products derived from malondialdehyde, their biogenesis remains controversial. We further characterize the chemical nature of lipofuscins in brain tissues from AD patients and normal aged subjects. Advanced glycation end products (AGEs), pentosidine and carboxymethyllysine (CML), were identified by appropriate specific antibodies. They have physicochemical properties similar to those of lipofuscin and also increase with aging. Pentosidine and CML were identified in the neuronal perikarya and the extraneuroperikaryal deposits of both the AD and aged brain. Pentosidine, but not CML, was present in the fiber-like structure within the neuropil and the core of classical senile plaque. In the brain of young subjects without CNS disease, pentosidine and CML staining was faint. Pentosidine and CML co-localized with lipofuscin pigments in the neuronal perikarya of both the AD and aged brain. We demonstrate for the first time that lipofuscin is constituted not only of lipid peroxidation products but also from glycation products which may be the origin of fluorescent pigments. Lipofuscins should thus be considered as fluorescent pigments generated by lipid- and sugar-derived Schiff base-protein polymers.