Dietary antioxidants protect hematopoietic cells and improve animal survival after total-body irradiation

The purpose of this study was to determine whether a dietary supplement consisting of L-selenomethionine, vitamin C, vitamin E succinate, alpha-lipoic acid and N-acetyl cysteine could improve the survival of mice after total-body irradiation. Antioxidants significantly increased the 30-day survival of mice after exposure to a potentially lethal dose of X rays when given prior to or after animal irradiation. Pretreatment of animals with antioxidants resulted in significantly higher total white blood cell and neutrophil counts in peripheral blood at 4 and 24 h after 1 Gy and 8 Gy. Antioxidants were effective in preventing peripheral lymphopenia only after low-dose irradiation. Antioxidant supplementation was also associated with increased bone marrow cell counts after irradiation. Supplementation with antioxidants was associated with increased Bcl2 and decreased Bax, caspase 9 and TGF-beta1 mRNA expression in the bone marrow after irradiation. Maintenance of the antioxidant diet was associated with improved recovery of the bone marrow after sublethal or potentially lethal irradiation. Taken together, oral supplementation with antioxidants appears to be an effective approach for radioprotection of hematopoietic cells and improvement of animal survival, and modulation of apoptosis is implicated as a mechanism for the radioprotection of the hematopoietic system by antioxidants.     

Effects of dietary supplements on space radiation-induced oxidative stress in Sprague-Dawley rats

Of particular concern for the health of astronauts during space travel is radiation from protons and high-mass, high-atomic-number (Z), and high-energy particles (HZE particles). Space radiation is known to induce oxidative stress in astronauts after extended space flight. In the present study, the total antioxidant status was used as a biomarker to evaluate oxidative stress induced by gamma rays, protons and HZE-particle radiation. The results demonstrate that the plasma level of total antioxidants in Sprague-Dawley rats was significantly decreased (P < 0.01) in a dose-dependent manner within 4 h after exposure to gamma rays. Exposure to protons and HZE-particle radiation also significantly decreased the serum or plasma level of total antioxidants in the irradiated animals. Diet supplementation with L-selenomethionine alone or a combination of selected antioxidant agents was shown to partially or completely prevent the decrease in the serum or plasma levels of total antioxidants in animals exposed to gamma rays, protons or HZE particles. These findings suggest that exposure to space radiation may compromise the capacity of the host antioxidant defense and that this adverse biological effect can be prevented at least partially by dietary supplementation with L-selenomethionine and antioxidants.     

The effect of n-3 long-chain polyunsaturated fatty acids and lipoic acid on the heart in the ovariectomized rat model of menopause

Menopause occurs as consequence of ovarian senescence that leads to a drop of oestrogen hormone. The decreased oestrogen levels combined with the impairment of the redox system may contribute to the increased risk of postmenopausal cardiovascular disease. Supplementation with antioxidants may be an alternative to reduce cardiovascular risk. The study evaluated the effect of dietary supplementation with docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and α-lipoic acid (LA) for a period of 16 weeks on oxidative stress biomarkers in the hearts of ovariectomized 3-month-old rats. Ovariectomy did not increase the level of the damage markers malondialdehyde and carbonyl, and both were decreased by LA supplementation. Ovariectomy increased the levels of the endogenous antioxidants glutathione, vitamin C and H₂O₂ consumption, after restoration by DHA, EPA, and LA supplementation. Vitamin E, glutathione peroxidase, glutathione-S-transferase, and superoxide dismutase are not altered by ovariectomy. Lipid and protein damage are not increased after ovariectomy and a portion of the endogenous antioxidants concomitantly increased, suggesting that hearts may be protected by these antioxidants. DHA, EPA, and LA restored these endogenous antioxidants, showing that all evaluated supplements are effective in modulating the antioxidant redox system in the heart. LA showed additional effect on redox markers, decreasing lipid and protein damage markers.     

Countermeasures against space radiation induced oxidative stress in mice

Of particular concern for the health of astronauts during space travel is radiation from protons and high atomic number (Z), high energy particles (HZE particles). Space radiation is known to induce oxidative stress in astronauts after extended space flight. In the present study, the total antioxidant status was used as a biomarker to evaluate oxidative stress induced by proton and HZE particle radiation in the plasma of CBA mice and the protective effect of dietary supplement agents. The results indicate that exposure to proton and HZE particle radiation significantly decreased the plasma level of total antioxidants in the irradiated CBA mice. Dietary supplementation with l-selenomethionine (SeM) or a combination of selected antioxidant agents (which included SeM) could partially or completely prevent the decrease in the total antioxidant status in the plasma of animals exposed to proton or HZE particle radiation. These findings suggest that exposure to space radiation may compromise the capacity of the host antioxidant defense system; this adverse biological effect can be prevented at least partially by dietary supplementation with agents expected to have effects on antioxidant activities.     

Methyl-donor nutrients inhibit breast cancer cell growth

Lipotropes (methyl group containing nutrients, including methionine, choline, folate, and vitamin B(12)) are dietary methyl donors and cofactors that are involved in one-carbon metabolism, which is important for genomic DNA methylation reactions and nucleic acid synthesis. One-carbon metabolism provides methyl groups for all biological methylation pathways and is highly dependent on dietary supplementation of methyl nutrients. Nutrition is an important determinant of breast cancer risk and tumor behavior, and dietary intervention may be an effective approach to prevent breast cancer. Apoptosis is important for the regulation of homeostasis and tumorigenesis. The anti-apoptotic protein Bcl-2 may be a regulatory target in cancer therapy; controlling or modulating its expression may be a therapeutic strategy against breast cancer. In this study, the effects of lipotrope supplementation on the growth and death of human breast cancer cell lines T47D and MCF-7 were examined and found to inhibit growth of both T47D and MCF-7 cells. Furthermore, the ratios of apoptotic cells to the total number of cells were approximately 44% and 34% higher in the lipotrope-supplemented treatments of T47D and MCF-7 cancer cells, respectively, compared with the control treatments. More importantly, Bcl-2 protein expression was decreased by approximately 25% from lipotrope supplementation in T47D cells, suggesting that lipotropes can induce breast cancer cell death by direct downregulation of Bcl-2 protein expression. Cancer treatment failure is often correlated with Bcl-2 protein upregulation. These data may be useful in the development of effective nutritional strategies to prevent and reduce breast cancer in humans.     

Dietary supplementation with α-tocopherol reduces neuroinflammation and neuronal degeneration in the rat brain after kainic acid-induced status epilepticus

Vitamin E (as α-tocopherol, α-T) is proposed to alleviate glia-mediated inflammation in neurological diseases, but such a role in epilepsy is still elusive. This study investigated the effect of α-T supplementation on glial activation, neuronal cell death and oxidative stress of rat brain exposed to kainate-induced seizures. Animals were fed for 2 weeks with a α-T-enriched diet (estimated intake of 750 mg/kg/day) before undergoing status epilepticus. Compliance to supplementation was demonstrated by the remarkable increase in brain α-T. Four days after seizure, brain α-T returned to baseline and lipid peroxidation markers decreased as compared to non-supplemented rats. Status epilepticus induced a lower up-regulation of astrocytic and microglial antigens (GFAP and MHC II, respectively) and production of pro-inflammatory cytokines (IL-1β and TNF-α) in supplemented than in non-supplemented animals. This anti-inflammatory effect was associated with a lower neuronal cell death. In conclusion, α-T dietary supplementation prevents oxidative stress, neuroglial over-activation and cell death occurring after kainate-induced seizures. This evidence paves the way to an anti-inflammatory and neuroprotective role of α-T interventions in epilepsy.     

Effect of low-level radiation on the death of male germ cells

Hormetic and adaptive responses induced by low-level radiation in hematopoietic and immune systems have been observed, as shown by stimulatory effects on cell growth and resistance to subsequent radiation-induced cytogenetic damage. However, in terms of cell death by apoptosis, the effects of low-level radiation are controversial: Some studies showed decreased apoptosis in response to low-level radiation while others showed increased apoptosis. This controversy may be related to the radiation doses or dose rates and also, more importantly, to the cell types. Testes are one of the most radiosensitive organs. The loss of male germ cells after exposure to ionizing radiation has been attributed to apoptosis. In the present study, the effects of low-level radiation at doses up to 200 mGy on mouse male germ cells in terms of apoptosis and the expression of apoptosis-related proteins were examined at different times after whole-body exposure of mice to low-level radiation. In addition, the effect of pre-exposure to low-level radiation on subsequent cell death induced by high doses of radiation was examined to explore the possibility of low-level radiation-induced adaptive response. The results showed that low-level radiation in the dose range of 25-200 mGy induced significant increases in apoptosis in both spermatogonia and spermatocytes, with the maximal effect at 75 mGy. The increased apoptosis is most likely associated with Trp53 protein expression. Furthermore, 75 mGy low-level radiation given pre-irradiation led to an adaptive response of seminiferous germ cells to subsequent high-level radiation-induced apoptosis. These results suggest that low-level radiation induces increased apoptosis in male germ cells but also induces a significant adaptive response that decreases cell death after a subsequent high-dose irradiation.     

STUDY OF VITAMIN A SUPPLEMENTATION IN CAPTIVE NORTHERN FUR SEALS (CALLORHINUS URSINUS) AND ITS EFFECT ON SERUM VITAMIN E

Two experiments were conducted to determine the effect of vitamin A supplementation on serum vitamin E in adult female northern fur seals ( Callorhinus ursinus ). In the first experiment five animals received, in addition to their routine dietary multivitamin supplement, a high-level vitamin A supplement (53 μmol retinyl palmitate/d) for 30 d. Five seals consuming their routine dietary supplement served as controls. Serum vitamin E decreased significantly in animals receiving high-level vitamin A supplements. At the end of 30 d serum vitamin E averaged 18.6 μg/mL in the control animals and 13.4 μg/mL in the animals receiving the high-Ieve1 vitamin A supplement. In experiment 2 ten animals received the high level vitamin A supplement for 60 d. After 30 d, serum vitamin E levels were reduced, but by 60 d had returned to baseline levels. However, the ratio of serum vitamin E to phospholipid, another index of vitamin E status, remained decreased. Although the exact mechanism of interaction is unknown, this study shows that when providing vitamin supplements for captive pinnipeds, vitamin interactions must be considered. The vitamin A supplementation currently used by some institutions seems unnecessary and may have detrimental effects on vitamin E status.     

Dietary supplementation with α-tocopherol reduces neuroinflammation and neuronal degeneration in the rat brain after kainic acid-induced status epilepticus

Abstract

Vitamin E (as α-tocopherol, α-T) is proposed to alleviate glia-mediated inflammation in neurological diseases, but such a role in epilepsy is still elusive. This study investigated the effect of α-T supplementation on glial activation, neuronal cell death and oxidative stress of rat brain exposed to kainate-induced seizures. Animals were fed for 2 weeks with a α-T-enriched diet (estimated intake of 750 mg/kg/day) before undergoing status epilepticus. Compliance to supplementation was demonstrated by the remarkable increase in brain α-T. Four days after seizure, brain α-T returned to baseline and lipid peroxidation markers decreased as compared to non-supplemented rats. Status epilepticus induced a lower up-regulation of astrocytic and microglial antigens (GFAP and MHC II, respectively) and production of pro-inflammatory cytokines (IL-1β and TNF-α) in supplemented than in non-supplemented animals. This anti-inflammatory effect was associated with a lower neuronal cell death. In conclusion, α-T dietary supplementation prevents oxidative stress, neuroglial over-activation and cell death occurring after kainate-induced seizures. This evidence paves the way to an anti-inflammatory and neuroprotective role of α-T interventions in epilepsy.     

Effects of quercetin and beta-carotene supplementation on azoxymethane-induced colon carcinogenesis and inflammatory responses in rats fed with high-fat diet rich in omega-6 fatty acids

Chronic inflammation in gastrointestinal tract has been suggested as a risk factor for tumor formation. The effect of dietary supplementation of quercetin or beta-carotene on colon carcinogenesis and inflammatory response in rats fed with high-fat diet rich in omega-6 fatty acids was assessed. Animals were exposed to two weekly subcutaneous injections of AOM (azoxymethane) at a single dose of 15 mg/kg body weight. A portion of rats from each group was sacrificed at 8 weeks after the last AOM treatment to determine ACF (aberrant crypt foci) formation. Colonic mucosa expression of iNOS (inducible nitric oxide) and COX-2 (cyclooxygenase-2) protein, and blood PGE2 (prostaglandin E2) level were measured. The remaining groups of animals were sacrificed at 33 weeks after the last AOM treatment to examine colon tumor formation. Rats on high-fat diet developed more aberrant crypt foci (P<0.05) compared with those of rats on regular diet. In the same vein, but in contrast to the effect seen with regular diet, the high-fat diet induced a significant up-regulation of iNOS expression. There was no significant change in the extent of COX-2 expression or in the PGE2 levels. Quercetin or beta-carotene supplementation reduced the number of ACF only in animals fed high-fat diet (p<0.05), however, no significant difference in tumor incidence was found. At week 33, the expression of iNOS was reduced by quercetin without a statistical significance, and COX-2 expression was slightly reduced in rats on beta-carotene supplementation. No change in PGE2 levels was observed. Whilst dietary antioxidants are considered as effective suppressors for precancerous lesion formation in colons exposed to high-risk diet, it is clear that elucidating the role of individual antioxidants in colon tumor formation coupled with an understanding of the molecular mechanisms involved would benefit colon cancer prevention strategies.     

Morin augments anticarcinogenic and antiproliferative efficacy against 7,12-dimethylbenz(a)-anthracene induced experimental mammary carcinogenesis

In general, oxidative stress resulting from an imbalance between prooxidant and antioxidant systems plays an important role in the pathogenesis of cancer. Morin (3,5,7,2',4'-pentahydroxyflavone), a member of the flavanol group, has been shown to possess chemopreventive potential against hepatocellular and colon cancer in experimental animals. Given the demonstrated importance of morin, aim of the present study was to evaluate the effect of morin on antiproliferative and anticarcinogenic effect against DMBA-induced experimental mammary carcinogenesis. Oral administration of 7,12-dimethylbenz(a)-anthracene (25 mg/kg body weight) to rats resulted in significant reduction of body weight, enzymic antioxidants (superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase), and nonenzymic antioxidants (reduced glutathione, vitamin C, and vitamin E). The levels of lipid peroxidation markers (thiobarbituric acid reactive substances and hydroperoxides) and tumor markers such as CA 15-3, AFP and CEA in serum were increased significantly in cancer-induced animals as compared to control rats. Oral supplementation of morin at a dose of 50 mg/kg body weight significantly improved the body weight, enzymic, and nonenzymic antioxidants and considerably decreased the lipid peroxidation marker and tumor markers levels. Histological observations also correlated with the biochemical parameters. Tumor bearing animals showed marked increase in proliferating cell nuclear antigen-positive cells and also the number of AgNOR/nuclei compared with control rats while this expression levels were significantly reduced upon morin treatment. Thus, this study reveals the possible beneficial effect of morin as chemopreventive agent against the oxidative stress induced during mammary carcinogenesis.     

Effects of Methionine Supplementation on the Expression of Protein Deposition-Related Genes in Acute Heat Stress-Exposed Broilers

The objective of this study was to evaluate the effect of heat stress and methionine supplementation on the gene expression of insulin-like growth factor I (IGF-I), growth hormone receptor (GHR), phosphatidylinositol 3-kinase, and regulatory 1 (PI3KR1) in the liver, as well as the expression of the atrogin 1 and cathepsin L2 (CTSL2) genes in the breast muscle of broilers. Broilers from 1–21 and 22–42 days of age were divided into three treatments related to methionine supplementation as follows: without methionine supplementation (MD), recommended level of methionine (DL1), and excess supplementation of methionine (DL2). The animals were either maintained at a thermal comfort temperature or exposed to heat stress (HS) (38°C for 24 hours, starting on day 20 or day 41 for experiments 1 and 2, respectively). The heat stress increased the body temperature at both ages. Starter period: The HS animals presented increased plasma creatinine content (P<0.0001) and the highest CTSL2 gene expression (P<0.0001). The methionine supplementation increased the IGF-I (P = 0.0144) and GHR (P = 0.0011) gene expression and decreased the CTSL2 (P = 0.0004) and atrogin 1 (P = 0.0012) gene expression. Grower period: Significant effects for the interaction between supplementation and environment were observed for GHR (P = 0.0252) and CTSL2 (P = 0.0011) gene expression. The highest GHR expression was observed in animals that remained in thermal comfort on the DL2 diet, and the lowest expression occurred in the HS animals fed the MD diet. For CTSL2, the HS animals fed the MD diet presented the highest CTSL2 gene expression, and the lowest expression was observed in the animals maintained at thermal comfort on DL1 and DL2 diets. Only methionine supplementation had effect on atrogin-1 gene expression (P<0.0001), with higher methionine content in the diet lower atrogin-1 gene expression was observed. Our results suggest that heat stress induces greater protein degradation and that methionine supplementation could induce protein deposition because methionine increased the expression of genes related to protein synthesis and decreased the expression of genes related to protein breakdown.     

Effects of methionine hydroxy analogue supplementation on the expression of antioxidant-related genes of acute heat stress-exposed broilers

We evaluated the effects of heat stress (HS) and methionine supplementation on biological markers of stress and expression of the genes for superoxide dismutase (SOD), thioredoxin (TRx), thioredoxin reductase 1 (TRxR1) and methionine sulfoxide reductase A (MsrA) in broilers aged 1 to 21 or 22 to 42 days. The broilers were divided into two treatments, one with the recommended level of methionine supplementation (MS, supplementation of dl-2-hydroxy-4-methylthiobutanoic acid (dl-HMTBA)) and one without methionine supplementation (MD). The animals were maintained at a temperature of thermal comfort or one of HS (38°C for 24 h). Mortality was only observed in 42-day-old broilers exposed to HS and fed the MD diet, and the rate was 5%. Starter period: we observed an interaction effect between diet and temperature on the gene expression of TRxR1 and MsrA, and expression of these genes was higher in the HS animals that received the MS diet than that in birds with the MD diet. Grower period: the expression of SOD, TRxR1 and MsrA genes, activities of aspartate aminotransferase (AST) and creatine kinase (CK) and content of creatinine were influenced by both study variables. In the HS animals, the expression of these genes, AST activity and creatinine content increased and CK activity decreased. In the animals on the MD diet, the expression of these genes and AST and creatinine values were higher and the CK activity was lower than those for the birds on the MS diet. Our results indicated that under HS conditions, the supplementation with dl-HMTBA could mitigate major damage caused by stress through the action on some genes related to TRx complex activity.     

Stress proteins as biomarkers of oxidative stress: effects of antioxidant supplements

The potential benefits to health of the supply of antioxidants, either through dietary intake or as supplements, is equivocal. There is a need to develop biomarkers that may act as monitors of cellular defense as influenced by antioxidant status. Thirty-two individuals participated in the project and 19 received supplements for 5 weeks in the form of a capsule containing a defined mixture of antioxidants. No change was noted in levels of superoxide dismutase and glutathione peroxidase following antioxidant supplementation. On the other hand, increase in total antioxidant status and decrease in malondialdehyde, protein carbonyl formation, and erythrocyte hemolysis were noted. In lymphocytes isolated from individuals receiving antioxidant supplements and subjected to a heat shock in the presence of the free radical generator 2, 2'-azobis-(2-amidinopropane)-dihydrochloride, enhanced synthesis of heat shock proteins hsp 105, hsp 90, hsp 70, and hsp 40 by contrast with decreased synthesis of heme oxygenase HO-1 (hsp 32) were noted. We conclude that antioxidant status modulates the synthesis of stress proteins.     

Mitigation of radiation-induced hematopoietic injury via regulation of cellular MAPK/phosphatase levels and increasing hematopoietic stem cells

Here we describe a novel strategy for mitigation of ionizing radiation-induced hematopoietic syndrome by suppressing the activity of MKP3, resulting in ERK activation and enhanced abundance of hematopoietic stem cells, using the antioxidant flavonoid baicalein (5,6,7-trihydroxyflavone). It offered complete protection to mouse splenic lymphocytes against radiation-induced cell death. Inhibitors of ERK and Nrf-2 could significantly abrogate baicalein-mediated radioprotection in lymphocytes. Baicalein inhibited phosphatase MKP3 and thereby enhanced phosphorylation of ERK and its downstream proteins such as Elk and Nrf-2. It also increased the nuclear levels of Nrf-2 and the mRNA levels of its dependent genes. Importantly, baicalein administration to mice before radiation exposure led to significant recovery of loss of bone marrow cellularity and also inhibited cell death. Administration of baicalein increased the hematopoietic stem cell frequency as measured by side-population assay and also by antibody staining. Further, baicalein offered significant protection against whole-body irradiation (WBI; 7.5 Gy)-induced mortality in mice. Interestingly, we found that baicalein works by activating the same target molecules ERK and Nrf-2 both in vitro and in vivo. Finally, administration of all-trans-retinoic acid (inhibitor of Nrf-2) significantly abrogated baicalein-mediated protection against WBI-induced mortality in mice. Thus, in contrast to the generalized conception of antioxidants acting as radioprotectors, we provide a rationale that antioxidants exhibit pleiotropic effects through the activation of multiple cellular signaling pathways.