Brain and Nerve Health

Brain α-Tocopherol Concentration and Stereoisomer Profile Alter Hippocampal Gene Expression in Weanling Mice

Justin S Rhodes, Catarina Rendeiro, Jonathan G Mun, Kristy Du, Pragya Thaman, Amanda Snyder, Heinrich Pinardo, Jenny Drnevich, Sriram Chandrasekaran, Chron-Si Lai, Karen J Schimpf, Matthew J Kuchan

J Nutr . 2020 Sep 16;nxaa249. doi: 10.1093/jn/nxaa249. Online ahead of print.

Abstract

Background: Alpha-tocopherol (αT), the bioactive constituent of vitamin E, is essential for fertility and neurological development. Synthetic αT (8 stereoisomers; all rac-αT) is added to infant formula at higher concentrations than natural αT (RRR-αT only) to adjust for bio-potency differences, but its effects on brain development are poorly understood.

Objectives: The objective was to determine the impact of bio-potency-adjusted dietary all rac-αT versus RRR-αT, fed to dams, on the hippocampal gene expression in weanling mice.

Methods: Male/female pairs of C57BL/6J mice were fed AIN 93-G containing RRR-αT (NAT) or all rac-αT (SYN) at 37.5 or 75 IU/kg (n = 10/group) throughout gestation and lactation. Male pups were euthanized at 21 days. Half the brain was evaluated for the αT concentration and stereoisomer distribution. The hippocampus was dissected from the other half, and RNA was extracted and sequenced. Milk αT was analyzed in separate dams.

Results: A total of 797 differentially expressed genes (DEGs) were identified in the hippocampi across the 4 dietary groups, at a false discovery rate of 10%. Comparing the NAT-37.5 group to the NAT-75 group or the SYN-37.5 group to the SYN-75 group, small differences in brain αT concentrations (10%; P < 0.05) led to subtle changes (<10%) in gene expression of 600 (NAT) or 487 genes (SYN), which were statistically significant. Marked differences in brain αT stereoisomer profiles (P < 0.0001) had a small effect on fewer genes (NAT-37.5 vs. SYN-37.5, 179; NAT-75 vs. SYN-75, 182). Most of the DEGs were involved in transcription regulation and synapse formation. A network analysis constructed around known vitamin E interacting proteins (VIPs) revealed a group of 32 DEGs between NAT-37.5 vs. SYN-37.5, explained by expression of the gene for the VIP, protein kinase C zeta (Pkcz).

Conclusions: In weanling mouse hippocampi, a network of genes involved in transcription regulation and synapse formation was differentially affected by dam diet αT concentration and source: all rac-αT or RRR-αT.

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Vitamin E reduces radiation injury of hippocampal neurons in mice by inhibiting ferroptosis

Chen Ren, Xuanzi Li, Shasha Du

Nan Fang Yi Ke Da Xue Xue Bao . 2020 Aug 30;40(8):1097-1102. doi: 10.12122/j.issn.1673-4254.2020.08.05.

Abstract

Objective: To explore the protective effect of vitamin E (VE) against radiation injury of hippocampal neurons in mice and explore the possible mechanism.

Methods: Cultured HT-22 and U251 cells with or without exposure to 8 Gy irradiation were treated with VE (200 μmol/L for 24 h), ferroptosis inhibitor (ferrostatin-1, 5 μmol/L for 24 h), apoptosis inhibitor (ZVAD-FMK, 2 μmol/L), or necroptosis inhibitor (100 μmol/L). MTT assay was used to evaluate the cell viability after the treatments, and reduced glutathione (GSH), malondialdehyde (MDA), lipid reactive oxygen species (lipid ROS), and intracellular iron ion levels were detected for assessment of ferroptosis. The mice exposed to 16 Gy irradiation with or without vitamin E (500 U/kg) treatment for 6 weeks were assessed for behavioral changes and cognitive functions using Morris water maze test.

Results: Treatment with VE significantly promoted the cell survival following irradiation in HT-22 cells (P &lt; 0.05) but not in U251 cells (P &gt; 0.05). Ferrostatin-1, but not ZVAD or the necroptosis inhibitor, promoted the survival of HT-22 cells following the irradiation. Exposure to irradiation significantly increased ferroptosis-related oxidative stress level in HT-22 cells, manifested by decreased GSH level and increased MDA, lipid ROS and intracellular iron ion levels (P &lt; 0.05); treatment with VE and ferrostatin-1 both obviously reversed radiation-induced ferroptosis-related oxidative stress in the cells (P &lt; 0.05). In Morris water maze test, the mice with radiation exposure showed obviously increased exploration time and distance (P &lt; 0.05), which were significantly decreased after treatment with VE (P &lt; 0.05).

Conclusions: Vitamin E reduces radiation injury by inhibiting ferroptosis in the hippocampal neurons in mice.

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Brain tocopherol levels are associated with lower activated microglia density in elderly human cortex

Francisca A de Leeuw, Julie A Schneider, Sonal Agrawal, Sue E Leurgans, Martha Clare Morris

Alzheimers Dement (N Y) . 2020 Aug 24;6(1):e12021. doi: 10.1002/trc2.12021. eCollection 2020.

Abstract

Introduction: Higher brain tocopherol levels have been associated with lower levels of Alzheimer’s disease (AD) neuropathology; however, the underlying mechanisms are unclear.

Methods: We studied the relations of α- and γ-tocopherol brain levels to microglia density in 113 deceased participants from the Memory and Aging Project. We used linear regression analyses to examine associations between tocopherol levels and microglia densities in a basic model adjusted for age, sex, education, apolipoprotein E (APOE)ε4 genotype (any ε4 allele vs. none) , and post-mortem time interval, and a second model additionally adjusted for total amyloid load and neurofibrillary tangle severity.

Results: Higher α- and γ-tocopherol levels were associated with lower total and activated microglia density in cortical but not in subcortical brain regions. The association between cortical α-tocopherol and total microglia density remained statistically significant after adjusting for AD neuropathology.

Discussion: These results suggest that the relation between tocopherols and AD might be partly explained by the alleviating effects of tocopherols on microglia activation.

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Garcinoic acid prevents β-amyloid (Aβ) deposition in the mouse brain

Rita Marinelli, Pierangelo Torquato, Desirée Bartolini, Cristina Mas-Bargues, Guido Bellezza, Antimo Gioiello, Consuelo Borras, Antonella De Luca, Francesca Fallarino, Bartolomeo Sebastiani, Sridhar Mani, Angelo Sidoni, Jose Viña, Manuela Leri, Monica Bucciantini, Pamela Nardiello, Fiorella Casamenti, Francesco Galli

J Biol Chem . 2020 Aug 14;295(33):11866-11876. doi: 10.1074/jbc.RA120.013303. Epub 2020 Jul 2.

Abstract

Garcinoic acid (GA or δ-T3-13’COOH), is a natural vitamin E metabolite that has preliminarily been identified as a modulator of nuclear receptors involved in β-amyloid (Aβ) metabolism and progression of Alzheimer’s disease (AD). In this study, we investigated GA’s effects on Aβ oligomer formation and deposition. Specifically, we compared them with those of other vitamin E analogs and the soy isoflavone genistein, a natural agonist of peroxisome proliferator-activated receptor γ (PPARγ) that has therapeutic potential for managing AD. GA significantly reduced Aβ aggregation and accumulation in mouse cortical astrocytes. Similarly to genistein, GA up-regulated PPARγ expression and apolipoprotein E (ApoE) efflux in these cells with an efficacy that was comparable with that of its metabolic precursor δ-tocotrienol and higher than those of α-tocopherol metabolites. Unlike for genistein and the other vitamin E compounds, the GA-induced restoration of ApoE efflux was not affected by pharmacological inhibition of PPARγ activity, and specific activation of pregnane X receptor (PXR) was observed together with ApoE and multidrug resistance protein 1 (MDR1) membrane transporter up-regulation in both the mouse astrocytes and brain tissue. These effects of GA were associated with reduced Aβ deposition in the brain of TgCRND8 mice, a transgenic AD model. In conclusion, GA holds potential for preventing Aβ oligomerization and deposition in the brain. The mechanistic aspects of GA’s properties appear to be distinct from those of other vitamin E metabolites and of genistein.

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A review on vitamin E natural analogues and on the design of synthetic vitamin E derivatives as cytoprotective agents

Panagiotis Theodosis-Nobelos, Georgios Papagiouvannis, Eleni A Rekka

Mini Rev Med Chem . 2020 Aug 7. doi: 10.2174/1389557520666200807132617. Online ahead of print.

Abstract

Vitamin E, essential for human health, is widely used worldwide for therapeutic or dietary reasons. The differences in the metabolism and excretion of the multiple vitamin E forms are presented in this review. The important steps that influence the kinetics of each form and the distribution and processing of vitamin E forms by the liver are considered. The antioxidant as well as non-antioxidant properties of vitamin E forms are discussed. Finally, synthetic tocopherol and trolox derivatives, based on the design of multitarget directed compounds, are reviewed. It is demonstrated that selected derivatization of vitamin E or trolox structures can produce improved antioxidants, agents against cancer, cardiovascular and neurodegenerative disorders.

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Brain γ-Tocopherol Levels Are Associated with Presynaptic Protein Levels in Elderly Human Midfrontal Cortex

Francisca A de Leeuw, William G Honer, Julie A Schneider, Martha Clare Morris

J Alzheimers Dis . 2020 Jul 25. doi: 10.3233/JAD-200166. Online ahead of print.

Abstract

Background: Higher vitamin E intake has been widely related to lower risks of cognitive decline and dementia. Animal models suggest that this relationship might be (partially) explained by the protection of vitamin E against presynaptic protein oxidation.

Objective: In this cross-sectional study, we aimed to examine the associations between brain tocopherols and presynaptic protein levels in elderly humans.

Methods: We examined associations of α- and γ-tocopherol brain levels with presynaptic protein levels in 113 deceased participants (age 88.5±6.0 years, 45 (40%) female) from the prospective Memory and Aging project. Three distinct presynaptic proteins, a SNARE protein composite, a synaptotagmin synaptophysin composite and the protein-protein interaction between synaptosomal-associated protein 25 (SNAP-25), and syntaxin were measured in two cortical brain regions. Linear regression models assessed associations of brain tocopherols with presynaptic protein levels.

Results: Higher brain γ-tocopherol levels were associated with higher levels of the SNARE protein composite, complexin-I, complexin-II, the synaptotagmin synaptophysin composite, and septin-5 in the midfrontal cortex (B(SE) = 0.272 to 0.412 (0.084 to 0.091), p < 0.001 to 0.003). When additionally adjusted for global Alzheimer’s disease pathology, cerebral infarcts, and Lewy body disease pathology, these associations remained largely similar. No associations were found between α-tocopherol and presynaptic protein levels.

Conclusion: In this cross-sectional study, we found higher brain γ-tocopherol levels were associated with presynaptic protein levels in the midfrontal cortex. These results are consistent with a proposed role of vitamin E to maintain presynaptic protein levels.

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Influence of specific management practices on blood selenium, vitamin E, and beta-carotene concentrations in horses and risk of nutritional deficiency

Mariya O Pitel, Erica C McKenzie, Jennifer L Johns, Robert L Stuart

J Vet Intern Med . 2020 Jul 20. doi: 10.1111/jvim.15862. Online ahead of print.

Abstract

Background: Selenium or alpha-tocopherol deficiency can cause neuromuscular disease. Beta-carotene has limited documentation in horses.

Objective: To evaluate the effect of owner practices on plasma beta-carotene concentration and risk of selenium and alpha-tocopherol deficiencies.

Animals: Three-hundred and forty-nine adult (≥1 year), university and privately owned horses and mules.

Methods: Cross-sectional study. Whole blood selenium, plasma alpha-tocopherol, and plasma beta-carotene concentrations were measured once. Estimates of daily selenium and vitamin E intake, pasture access, and exercise load were determined by owner questionnaire. Data were analyzed using t tests, Mann-Whitney tests, parametric or nonparametric analysis of variance (ANOVA), Kruskal-Wallis test, Spearman’s correlation and contingency tables (P < .05).

Results: Nearly 88% of the horses received supplemental selenium; 71.3% received ≥1 mg/d. Low blood selenium concentration (<80 ng/mL) was identified in 3.3% of horses, and 13.6% had marginal concentrations (80-159 ng/mL). Non-supplemented horses were much more likely to have low blood selenium (odds ratio [OR], 20.2; 95% confidence interval [CI], 9.26-42.7; P < .001). Supplemental vitamin E was provided to 87.3% of horses; 57.7% received ≥500 IU/d. Deficient (<1.5 μg/mL) and marginal (1.5-2.0 μg/mL) plasma (alpha-tocopherol) occurred in 15.4% and 19.9% of horses, respectively. Pasture access (>6 h/d) and daily provision of ≥500 IU of vitamin E was associated (P < .001) with higher plasma alpha-tocopherol concentrations. Plasma beta-carotene concentration was higher in horses with pasture access (0.26 ± 0.43 versus 0.12 ± 0.13 μg/mL, P = .003).

Conclusions and clinical importance: Suboptimal blood selenium and plasma alpha-tocopherol concentrations occurred in 16.7% and 35.5% of horses, respectively, despite most owners providing supplementation. Inadequate pasture access was associated with alpha-tocopherol deficiency, and reliance on selenium-containing salt blocks was associated with selenium deficiency.

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The assessment of possible gender-related effect of endogenous striatal alpha-tocopherol level on MPTP neurotoxicity in mice

Nikolett Nánási, Gábor Veres, Edina K Cseh, Diána Martos, Levente Hadady, Péter Klivényi, László Vécsei, Dénes Zádori

Heliyon . 2020 Jul 11;6(7):e04425. doi: 10.1016/j.heliyon.2020.e04425. eCollection 2020 Jul.

Abstract

Several studies supported an increased vulnerability of males regarding Parkinson’s disease (PD) and its animal models, the background of which has not been exactly revealed, yet. In addition to hormonal differences, another possible factor behind that may be a female-predominant increase in endogenous striatal alpha-tocopherol (αT) level with aging, even significant at 16 weeks of age, previously demonstrated by the authors. Accordingly, the aim of the current study was the assessment whether this difference in striatal αT concentration may contribute to the above-mentioned distinct vulnerability of genders to nigrostriatal injury. Female and male C57Bl/6 mice at the age of 16 weeks were injected with 12 mg/kg body weight 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) 5 times at 2 h intervals or with saline. The levels of some biogenic amines (striatum) and αT (striatum and plasma) were determined by validated high performance liquid chromatography methods. Although the results proved previous findings, i.e., striatal dopamine decrease was less pronounced in females following MPTP treatment, and striatal αT level was significantly higher in female mice, the correlation between these 2 variables was not significant. Surprisingly, MPTP treatment did not affect striatal αT concentrations, but significantly decreased plasma αT levels without differences between genders. The current study, examining the possible role of elevated αT in female C57Bl/6 mice behind their decreased sensitivity to MPTP intoxication for the first time, was unable to demonstrate any remarkable connection between these 2 variables. These findings may further confirm that αT does not play a major role against neurotoxicity induced by MPTP.

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Administration of Vitamin D 3 and E supplements reduces neuronal loss‏ and oxidative stress in a model of rats with Alzheimer’s disease

Shima Mehrabadi, Seyed Shahabeddin Sadr

Neurol Res . 2020 Jul 4;1-7. doi: 10.1080/01616412.2020.1787624. Online ahead of print.

Abstract

Alzheimer’s disease (AD) is the most common neurodegenerative disease across the world. The major cause of AD is extensive oxidative stress and inflammation in central nervous system (CNS). Vitamin D3 and E are the most known vitamins that control oxidative stress and mitochondrial respiratory function. They may prevent neuronal loss in AD. Few studies have been conducted to assess the effect of vitamins on AD. Therefore, the aim of this study was to assess the effect of vitamin D3 and E on AD. Methods: In this study, 60 rats were randomly divided into six groups (n = 10) namely the control group, sham group, AD group with intra-hippocampal Aβ1-40 injection, AD+vitamin D3 group, AD+vitamin E group and AD+vitamin D3 and E group. Memory and learning were measured by the Novel Object Recognition (NOR) test. Neuronal survival was assessed by H&E and cresyl violet staining, and oxidative stress was measured by malondialdehyde (MDA) level and superoxide dismutase (SOD) activity. In vitamin-treated groups, learning and memory, which were measured by NOR, improved significantly. Vitamin D3 and E administration decreased neuronal loss in AD brain rats. Results: Results showed that MDA decreased and SOD increased in treatment groups; but, a combination of vitamin D3 and E was more effective in decreasing oxidative stress in AD compared to other treatment groups. Conclusion: The present study indicated that vitamin D3 and E and their combination can improve memory and learning deficit, and decrease neuronal loss and oxidative stress in Alzheimer’s model.

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Infant Rhesus Macaque Brain α-Tocopherol Stereoisomer Profile Is Differentially Impacted by the Source of α-Tocopherol in Infant Formula

Matthew J Kuchan, Katherine M Ranard, Priyankar Dey, Sookyoung Jeon, Geoff Y Sasaki, Karen J Schimpf, Richard S Bruno, Martha Neuringer, John W Erdman

J Nutr . 2020 Jul 2;nxaa174. doi: 10.1093/jn/nxaa174. Online ahead of print.

Abstract

Background: α-Tocopherol (αT) in its natural form [2’R, 4’R, 8’R αT (RRR-αT)] is more bioactive than synthetic α-tocopherol (all rac-αT). All rac-αT is widely used in infant formulas, but its accretion in formula-fed infant brain is unknown.

Objective: We sought to compare αT and stereoisomer status in infant rhesus macaques (Macaca mulatta) fed infant formula (RRR-αT or all rac-αT) with a reference group fed a mixed diet of breast milk and maternal diet.

Methods: From 1 d after birth until 6 mo of age, infants (n = 23) were either nursery reared and exclusively fed 1 of 2 formulas by staff personnel or were community housed with their mothers and consumed a mixed reference diet of breast milk (69 mL/d at 6 mo) transitioning to monkey diet at ∼2 mo (MF; n = 8). Formulas contained either 21 μmol RRR-αT/L (NAT-F; n = 8) or 30 μmol all rac-αT/L (SYN-F; n = 7). Total αT and αT stereoisomers were analyzed in breast milk at 2, 4, and 6 mo and in monkey plasma and liver and 6 brain regions at 6 mo of age. α-Tocopherol transfer protein (α-TTP), lipoprotein αT, and urinary α-carboxyethyl-hydroxychroman (α-CEHC) were measured. One-way ANOVA with Tukey’s post-hoc test was used for analysis.

Results: At study termination, plasma, liver, lipoprotein, and brain total αT did not differ between groups. However, the NAT-F-fed group had higher RRR-αT than the SYN-F-fed group (P < 0.01) and the MF group (P < 0.0001) in plasma (1.7- and 2.7-fold) and brain (1.5- and 2.5-fold). Synthetic αT 2R stereoisomers (SYNTH-2R) were generally 3- and 7-fold lower in brain regions of the NAT-F group compared with those of the SYN-F and MF groups (P < 0.05). SYNTH-2R stereoisomers were 2-fold higher in MF than SYN-F (P < 0.0001). The plasma percentage of SYNTH-2R was negatively correlated with the brain percentage of RRR-αT (r = -0.99, P < 0.0001). Brain αT profiles were not explained by α-TTP mRNA or protein expression. Urine α-CEHC was 3 times higher in the NAT-F than in the MF group (P < 0.01).

Conclusions: Consumption of infant formulas with natural (NAT-F) compared with synthetic (SYN-F) αT differentially impacted brain αT stereoisomer profiles in infant rhesus macaques. Future studies should assess the functional implications of αT stereoisomer profiles on brain health.

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