Oxidative stress and antioxidant status in mouse liver: effects of dietary lipid, vitamin E and iron

Effect of zinc on the lipid peroxidation and the antioxidant defense systems of the alloxan-induced diabetic rabbits

The effects of oral zinc supplementation on lipid peroxidation and the antioxidant defense system of alloxan (80-90 mg/kg)-induced diabetic rabbits were examined. Forty-five New Zealand male rabbits, 1 year old, weighing approximately 2.5 kg, were allocated randomly and equally as control, diabetic, and zinc-supplemented diabetic groups. After diabetes was induced, zinc-supplemented diabetic rabbits had 150 mg/L of zinc as zinc sulfate (ZnSO(4)) in their drinking tap water for 3 months. The feed and water consumption was higher in diabetic groups than (P<0.01) healthy rabbits. The body weight was lower in diabetic rabbits compared to control. The blood glucose levels were higher in diabetic groups than controls. The elevated plasma malondialdehyde (MDA) levels were determined in the diabetic group (P<0.01). The glutathione peroxidase (GSH-Px), catalase (CAT), superoxide dismutase (SOD), glutathione (GSH), and ceruloplasmin levels in the diabetic group were decreased by the effect of diabetes but there was no difference between zinc-supplemented diabetic and control rabbits. Serum zinc concentrations were lower in diabetic rabbits but iron (Fe) and copper (Cu) levels in sera were not different among the groups. As a result, it was concluded that daily zinc supplementation could reduce the harmful effects of oxidative stress in diabetics.

Raised saturated-fat intake worsens vascular function in virgin and pregnant offspring of streptozotocin-diabetic rats

Adult offspring of severely diabetic pregnant rats are insulin resistant and display cardiovascular dysfunction. When pregnant they develop mild hyperglycaemia. Diets high in saturated fat have been implicated in the development of cardiovascular disease and vascular dysfunction. In the present study we have determined vascular function in small mesenteric arteries from offspring of normal (OC) and diabetic (OD) rats fed standard chow and offspring of diabetic rats fed a diet high in saturated fats (OD-HF) from weaning to adulthood, and throughout their subsequent pregnancies. OD rats displayed an increased sensitivity to noradrenaline (P < 0·05) and impaired sensitivity to the endothelium-dependent vasodilator, acetylcholine. The component of acetylcholine-induced relaxation attributable to endothelium-derived hyperpolarizing factor was reduced in OD-HF rats. Pregnant OD rats also demonstrated impaired maximum relaxation to acetylcholine (pregnant OD rats v. pregnant OC rats P < 0·05). In pregnant OD-HF rats noradrenaline sensitivity was enhanced and endothelium-dependent relaxation further reduced (pregnant OD-HF rats v. pregnant OC rats P < 0·001). The isoprostane, 8-epi-prostaglandin F2α, a marker of oxidative stress, was increased in pregnant OD rats (pregnant OD rats v. pregnant OC rats P < 0·001) and further increased in pregnant OD-HF rats (pregnant OD-HF rats v. pregnant OD rats P < 0·05). We conclude that a high-saturated-fat diet leads to deterioration in specific components of vascular function in OD rats. When pregnant, vascular function of OD-HF rats is further compromised. Pregnancy in the OD rats is associated with a striking increase in a marker of oxidative stress, which increases further if the saturated fat intake is raised.

Vitamin E, aging and Leydig cell steroidogenesis

Previous studies have suggested that oxidant-induced damage may play a role in the reduced ability of aged Brown Norway rat Leydig cells to produce testosterone. We reasoned that if this was the case, antioxidants such as vitamin E (VE) would be expected to have protective effects on steroidogenesis. To test this hypothesis, the effects of VE on Leydig cell steroidogenesis were examined both in vitro and in vivo. In vitro studies were conducted using Leydig cells isolated from the testes of young adult Brown Norway rats. In one experiment, isolated cells were incubated with luteinizing hormone (LH) alone or with LH plus VE (1.3-40 microg/ml). At each of 3, 5 and 7 days thereafter, the ability of the cells to produce testosterone was greater in the presence of VE than in its absence, and depended upon VE dose. Culturing the Leydig cells with the antioxidants melatonin or N-tert-butyl-alpha-phenylnitrone also protected Leydig cell steroidogenic function. Additionally, VE was found to suppress Fe2+/sodium ascorbate-induced lipid peroxidation in Leydig cells. These studies strongly supported the contention that VE has a protective effect on Leydig cell steroidogenesis. These in vitro results prompted us to ask whether, in vivo, VE also would affect steroidogenesis as Leydig cells age. To this end, rats were provided one of three diets, begun when the rats were 6 months of age and carried out through age 25 months: VE-deficient, VE-control, or VE-supplemented. The VE-deficient diet had no effect on the age-related reductions in Leydig cell testosterone production observed in VE-control rats. The VE-supplemented diet did not prevent age-related reductions in steroidogenesis, but the reductions at ages 23 and 25 months were significantly less than those seen in Leydig cells from VE-control or VE-deficient rats. Taken together, the results of the in vitro and in vivo studies reported herein are consistent with the conclusion that vitamin E exerts a protective effect on Leydig cell steroidogenesis.

Suppression of oxidative stress in aging NZB/NZW mice: effect of fish oil feeding on hepatic antioxidant status and guanidino compounds

Oxidative stress caused by excessive reactive species (RS) and lipid peroxidation is known to be casually linked to age-related inflammation. To test the hypothesis that fish oil (FO) intake has a beneficial effect on nephritis due to its suppressive action of oxidative stress and the enhancement of antioxidant defenses, we examined the effect of dietary FO on various oxidative stress-related parameters and guanidino compound (GC) levels using (NZB x NZW) F1 (B/W) mice. These mice were fed diets supplemented with either 5% corn oil (control) or 5% FO. At 4 and 9 months of age, the hepatic oxidative status was estimated by assessing RS generation produced from xanthine oxidase, the prostaglandin pathway and lipid peroxidation. To evaluate the effect of FO on redox status, including antioxidant defenses, GSH and GSSG levels and antioxidant enzyme activities were measured. To correlate the extent of oxidative status with the nephritic condition, creatinine, guanidino acetic acid and arginine levels were measured. Results indicated that increased levels of lipid peroxidation, RS generation and xanthine oxidase activity with age were all significantly suppressed by FO feeding. Furthermore, reduced GSH levels, GSH/GSSG ratio and antioxidant enzyme activities in the FO-fed mice were effectively enhanced compared to the corn oil-fed mice. Among several GCs, the age-related increase of creatinine level was blunted by FO. Based on these results, we propose that dietary FO exerts beneficial effects in aged, nephritic mice by suppressing RS, superoxide and lipid peroxidation, and by maintaining a higher GSH/GSSG ratio and antioxidant enzyme activities.

Including walnuts in a low-fat/modified-fat diet improves HDL cholesterol-to-total cholesterol ratios in patients with type 2 diabetes

OBJECTIVE

The aim of this study was to examine the effect of a moderate-fat diet inclusive of walnuts on blood lipid profiles in patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

This was a parallel randomized controlled trial comparing three dietary advice groups each with 30% energy as fat: low fat, modified low fat, and modified low fat inclusive of 30 g of walnuts per day. Fifty-eight men and women, mean age 59.3 +/- 8.1 years, started the trial. Dietary advice was given at baseline with monthly follow-up and fortnightly phone calls for support. Body weight, percent body fat, blood lipids, HbA1c, total antioxidant capacity, and erythrocyte fatty acid levels were measured at 0, 3, and 6 months. Data were assessed by repeated-measures ANOVA with an intention-to-treat model.

RESULTS

The walnut group achieved a significantly greater increase in HDL cholesterol-to-total cholesterol ratio (P=0.049) and HDL (P=0.046) than the two other treatment groups. A 10% reduction in LDL cholesterol was also achieved in the walnut group, reflecting a significant effect by group (P=0.032) and time (P=0.036). There were no significant differences between groups for changes in body weight, percent body fat, total antioxidant capacity, or HbA1c levels. The higher dietary polyunsaturated fat-to-saturated fat ratio and intakes of omega-3 fatty acids in the walnut group were confirmed by erythrocyte biomarkers of dietary intake.

CONCLUSIONS

Structured "whole of diet" advice that included 30 g of walnuts/day delivering substantial amounts of polyunsaturated fatty acid improved the lipid profile of patients with type 2 diabetes.

Protective Effects of Vitamin A and Vitamin E Succinate against 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD)-Induced Body Wasting, Hepatomegaly, Thymic Atrophy, Production of Reactive Oxygen Species and DNA Damage in C57BL/6J Mice

The protective effect of vitamin A and vitamin E succinate against 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced acute toxicity and measures of oxidative stress was studied. Ten mice were treated with either vitamin A (50 mg/kg every other day for eight days) or vitamin E succiante (150 mg/kg/day followed by a dose of 40 mg/kg/day for five additional days). Half of each of the above groups of animals received TCDD on day 4. Five mice received corn oil or TCDD alone. After five days of TCDD treatment, antioxidant combination treatment with vitamin A and TCDD or vitamin E succinate and TCDD resulted in a significant reduction in indicators of acute toxicity including the decrease in total body and thymus weight as compared to TCDD alone (P<0.05). The combination treatment produced also a significant reduction in the increase in liver weight as compared to TCDD only (P<0.05). Following one day of treatment with 50 microg TCDD/kg, vitamin A and vitamin E succinate produced a significant decrease in the production of superoxide anion by peritoneal lavage cells (P<0.05) and in DNA-single strand breaks in the same cells (P<0.05) as assessed by the reduction of cytochrome c and the alkaline elution technique, respectively. A significant decrease in DNA-single strand breaks in peritoneal lavage cells was observed following 5 days treatment with 50 microg TCDD/kg (P<0.05). The results indicate a potential role for oxidative stress in the acute toxicity of TCDD and a protective effect for vitamin A and vitamin E succinate in the overall toxicity of TCDD including measures of oxidative stress.

Temporal changes in cerebral antioxidant enzyme activities after ischemia and reperfusion in a rat focal brain ischemia model: effect of dietary fish oil

This study investigated the neuroprotective effects of dietary supplementation of fish oil on both brain infarction and the activities of antioxidant enzymes. Male Sprague-Dawley rats (4-weeks old) were divided into two groups and received either a regular diet (RD) or a fish-oil-supplemented diet (FOD) for 6 weeks prior to middle cerebral artery (MCA) occlusion. The infarction volume of the brain was calculated using image analysis after staining. Antioxidant enzymes were measured before ischemia (BI), after 2 h of ischemia (AI) and after 24 h (24hR), 48 h (48hR) and after 7 days (7dR) of reperfusion. The infarction volume of the brain was significantly smaller in the FOD group than in the RD group after 24 h of reperfusion (p<0.05). Before ischemia, the levels of lipid peroxide and the glutathione peroxidase (GPx) activity were higher in the FOD group than in the RD group. During reperfusion, the catalase (CAT) activity in the FOD group remained at the preischemia level until after 48 h of reperfusion, while those in the RD group did not. The Mn-superoxide dismutase (SOD) activity and GPx activity were higher in the FOD group than in the RD group only after 2 h of ischemia. In the fatty acid analysis, the ratio of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) were higher in the FOD group than in the RD group (p<0.05). Our results demonstrate that supplementing the diet with fish oil could decrease the cerebral infarction volume following ischemia and reperfusion (I/R) partly by working directly as an antioxidant and partly by modulating antioxidant enzyme activities.

Gene expression profile of oxidant stress and neurodegeneration in transgenic mice deficient in alpha-tocopherol transfer protein

Alpha-tocopherol transfer protein (TTP) regulates the retention and secretion of alpha-tocopherol (alpha-T) by the liver. Deletion of the TTP gene (Ttpa) in mice results in systemic deficiency of alpha-T and neurological dysfunctions described in patients with mutated Ttpa. We have explored genome-wide changes in mRNAs from brain cortex and liver of Ttpa-deficient (Ttpa(-/-)) mice and wild-type (Ttpa(+/+)) mice. Selective inductions of genes regulated by antioxidant response elements were detected in Ttpa(-/-) livers compared to Ttpa(+/+) livers, suggesting increased oxidant stress in Ttpa(-/-) livers. The activation of cell proliferation pathways in Ttpa(-/-) livers was indicated by the induction of genes that encode growth factor-binding proteins, mitogen-activated protein kinase kinase 3, and apoptosis inhibitor 6. The induction of synuclein-alpha and repression of synuclein-beta genes was detected in Ttpa(-/-) cortex. This may predispose Ttpa(-/-) cortex to increased formation of synuclein-alpha aggregates and Lewy body, often associated with oxidant stress. Cortex of Ttpa(-/-) mice revealed repression of genes encoding synaptic proteins, protein kinase C family members, and myelin proteins. A 13-fold decrease in the expression of retinoic acid receptor-related orphan receptor-alpha mRNA predicts staggerer-like phenotype (ataxia and deficits of motor coordination) of Ttpa(-/-) mice. The repression of specific genes that determine synaptic plasticity and neuronal development may account for suppressed electrophysiological activities of cortex and impaired behavior in Ttpa(-/-) mice.

Virgin olive and fish oils enhance the hepatic antioxidant defence system in atherosclerotic rabbits

BACKGROUND & AIMS

In this study we report the effects of sunflower, virgin olive and fish oils on the lipid profile and antioxidant defence system in liver mitochondria from rabbits with experimental atherosclerosis.

METHOD

An atherogenic control group were fed for 50 days on a diet containing 3% lard and 1.3% cholesterol. Four groups were fed for an additional period of 30 days with a diet enriched in different oils: sunflower oil, virgin olive oil, refined olive oil and fish oil. A control group was fed with a standard chow.

RESULTS

The atherogenic diet caused important changes in the hepatic mitochondria lipid profile and in the enzymatic and non-enzymatic antioxidant defence system accompanied with an increase in the content of hydroperoxides in liver mitochondria. The administration of virgin olive and fish oils showed a better profile in the antioxidant system as well as decrease in the content of hydroperoxides.

CONCLUSIONS

The intake of cholesterol- and lard-enriched diet leads to a high impairment in the hepatic antioxidant defence system. However, the replacement of that diet by other unsaturated fat-enriched diets using virgin olive, sunflower and fish oil enhances hepatic antioxidant defence system, virgin olive and fish oil diet provide the best results.

Effect of short-term and long-term antioxidant therapy on primary and secondary ageing neurovascular processes

Previous studies from our laboratory demonstrated an age-related functional decline in sensory neurones and their modulation of microvascular blood flow (primary ageing processes) that correlated with a deficiency in tissue repair (a secondary ageing process). We also raised the notion of a possible role for free radicals in these age-related changes. The aim of this study was to investigate the impact of antioxidant therapy on modulating sensory neurovascular function and tissue repair with age. Twenty-four-month-old Sprague-Dawley rats were treated with vitamin E for short-term (40 mg/kg, i.p., every other day for 2 weeks) or long-term (for 12 months in advance, 10 g/kg, incorporated in food). These treated rats were assessed for the effectiveness of treatment and tested for their sensory neurovascular function, repair of full-thickness burn, and recovery from hyperalgesia following nerve injury. The results indicate that both short- and long-term vitamin E treatments are effective in improving sensory neurovascular function and in reducing the time required for complete wound closure of full-thickness burn injury. Short-term vitamin E treatment was more effective in protecting against the development of hyperalgesia following nerve injury. An initial increase in wound size and in hyperalgesia was observed in the treated animals, and could reflect possible side effects of the antioxidant therapy and support the importance of free radicals in early stages of the repair process. The data, overall, support the notion that oxidative damage contributes to both primary and secondary ageing processes.

Supplementation with vitamin E fails to attenuate oxidative damage in aged mice

The validity of the oxidative stress hypothesis of aging has sometimes been questioned because the administration of low molecular weight antioxidants such as alpha-tocopherol does not retard the aging process and extend maximum life span. Thus, the goal of the current study was to determine if increased oral intake of alpha-tocopheryl acetate indeed results in its augmentation in tissues or in their mitochondria, and whether or not this causes an attenuation of oxidative damage. Groups of relatively old (21 months) experimental mice were fed a diet supplemented with 1.65 g/kg alpha-tocopheryl acetate or the base diet (NIH-31), for 13 weeks. Supplementation with alpha-tocopheryl acetate increased alpha-tocopherol concentrations approximately 3-5-fold in plasma and in tissue homogenates and approximately 2-3-fold in mitochondria from liver, skeletal muscle and heart of the mice. However, supplementation affected neither the rate of heart mitochondrial H(2)O(2) generation nor products of lipid peroxidation (thiobarbituric acid-reactive substances) and protein oxidation (protein carbonyls). Thus, in contrast to life-extending interventions such as caloric restriction, that can produce relatively rapid decreases in oxidative damage, supplementation with alpha-tocopheryl acetate had little or no impact on the steady-state level of cellular oxidative damage. This difference could explain why alpha-tocopherol administration has been found to be ineffective in the extension of the life span.

Quantification of antioxidant activity in brain tissue homogenates using the 'total equivalent antioxidant capacity'

We demonstrate herein that the standard 'Trolox equivalent antioxidant capacity' (TEAC) assay, typically utilized to quantify total antioxidant levels within plasma, can also be utilized for tissue homogenates. Normal mice and transgenic mice lacking apolipoprotein E were subjected to a diet including iron as a generic pro-oxidant for 1 month (which has been shown to induce oxidative damage in our prior studies) and homogenates of brain tissue were subjected to the TEAC assay. Levels of the endogenous antioxidant glutathione levels were also monitored by HPLC. As described previously, ApoE-deficient mice expressed increased levels of glutathione; total antioxidant levels, as determined by TEAC, were increased to a similar extent. The increase in total antioxidant levels, as determined by TEAC, following dietary iron challenge paralleled the increase in glutathione levels, as determined by HPLC. These findings indicate that the TEAC assay may be useful for tissue homogenates. The rapid nature of this assay compared to HPLC, coupled with its lack of requirement for sophisticated equipment, makes it well suited for analyses of multiple tissue samples.

IRP1 activity and expression are increased in the liver and the spleen of rats fed fish oil-rich diets and are related to oxidative stress

Many clinical studies have indicated that diets rich in fish oil (FO) reduce the risk of cardiovascular disease and have anti-inflammatory and antithrombotic properties. Although the therapeutic effects of FO have been well described, their impact on iron metabolism remains unclear. The aim of this work was to study the activity and expression of IRP1 in the liver and the spleen of rats fed FO-rich diets with 0 (FO-0) or 100 (FO-1) mg/kg of all-rac-alpha-tocopherol acetate. We also measured nonheme iron, alpha-tocopherol and retinol concentrations, and superoxide (SOD) and catalase activity in these organs. Rats fed FO were compared to rats fed a corn oil (CO)-rich diet with 100 mg/kg all-rac-alpha-tocopherol acetate. The activity and expression of IRP1 in both the liver and the spleen of rats fed FO diets were greater than in those fed the CO diet. FO-fed rats also had lower nonheme iron concentrations in these organs. Hepatic alpha-tocopherol and retinol concentrations and SOD activity were lower in FO-0-fed rats compared to those fed the CO diet. In the spleen, alpha-tocopherol and retinal concentrations were not altered but SOD activity was lower in FO-0- fed rats, whereas catalase activity was greater than in rats fed CO. The results indicate that there is an increase in oxidative stress in the liver and in the spleen of rats fed FO diets. These changes, together with the reduction of nonheme iron concentrations in both FO-0- and FO-1-fed rats, may explain the increase in activity and expression of IRP1. Therefore, the ingestion of FO-rich diets should be monitored under close supervision.

Dietary (n-3) fat and cholesterol alter tissue antioxidant enzymes and susceptibility to oxidation in SHR and WKY rats

Previously, 8% fish oil blend diets, compared to butter and soybean oil blend diets, reduced specific antioxidant enzyme activities and tissue susceptibility to in vitro oxidative stress in spontaneously hypertensive (SHR) and Wistar Kyoto (WKY) rats. Moreover, high cholesterol (5.0 g/kg diet) diets protected against in vitro tissue lipid oxidation. In this study, we hypothesized that 160 g fat/kg diet as blends of (n-6) or (n-3) oils and cholesterol would alter antioxidant enzyme activities and thus increase tissue susceptibility to oxidation. The effects of diet blends of saturated (butter, B), (n-6) (soybean oil, SBO) or (n-3) (menhaden oil, MO) oils with cholesterol (0.5 or 5.0 g/kg) on systolic blood pressure (SBP), plasma lipids, antioxidant enzymes and susceptibility to oxidation were examined in SHR and WKY rats. SBP at 13 wk of age was greater (P < 0.001) in SHR than in WKY rats, but was not affected by diets. Plasma cholesterol and triacylglycerols were decreased (P < 0.001) by MO diets. Hepatic glutathione reductase activities were reduced (P < 0.001) in SBO-fed SHR and enhanced in SBO- and MO-fed WKY rats. Glutathione levels were reduced (P < 0.001) in RBC and enhanced (P < 0.001) in livers of MO-fed rats. Lipid oxidation was enhanced (P < 0.001) in red blood cells (RBC) from SBO groups, and hearts and livers of MO groups. High cholesterol diets reduced (P < or = 0.001) susceptibility to lipid peroxidation in RBC and liver of SHR and WKY rats. Greater amounts of dietary (n-3) fat enhance tissue susceptibility to oxidation, which can be modulated by increased dietary cholesterol in SHR and WKY rats.

Carbohydrate-energy restriction may protect the rat brain against oxidative damage and improve physical performance

Chronic energy restriction, alpha-tocopherol supplementation and their interaction with exhaustive exercise were investigated. Eleven-week-old male Wistar rats (n 6x 10) were fed either a control (C), a 30 % carbohydrate-energy-restricted control (R) or an alpha-tocopherol-supplemented (S) diet for 5 months. The animals in each diet were divided into exercised (E) and non-exercised (NE) groups. Before killing, the exercised rats were required to run to exhaustion (39 (se 6), 69 (se 11) and 18 (se 2) min for the C, R and S groups, respectively). Lipid peroxidation (thiobarbituric acid-reactive substances; TBARS), protein damage (reactive carbonyls) and alpha-tocopherol were determined in gastrocnemius, liver, brain and/or plasma. There was no difference in lipid peroxidation between the R and C groups, but in liver and muscle peroxidation appeared significantly lower in the S than the other two diets. TBARS in the brain were similar in all groups. On the other hand, reactive carbonyls showed that both the R and S diets reduced protein damage in the brain, while exhaustive exercise increased it. For liver and muscle, however, reactive carbonyl levels were similar in all groups. alpha-Tocopherol supplementation increased the vitamin concentrations in liver, muscle and plasma, but exercise decreased them in plasma and brain. Carbohydrate-energy restriction increased (P=0.0025) resistance to exhaustive exercise considerably without depleting stores of alpha-tocopherol or exacerbating oxidative damage in monitored tissues. It is concluded that while exhaustive exercise promotes a tissue-specific oxidative damage detectable only in brain proteins, both experimental diets tended to ameliorate this condition.

Improved antioxidant and fatty acid status of patients with cystic fibrosis after antioxidant supplementation is linked to improved lung function

BACKGROUND

Oxidative stress, as measured by 8-iso-prostaglandin F(2)(alpha) (8-iso-PGF(2)(alpha)), and depleted antioxidant defenses were shown in stable cystic fibrosis (CF) patients. The plasma fatty acid status of CF patients was linked to oxidative stress after respiratory exacerbations.

OBJECTIVE

We examined changes in plasma 8-iso-PGF(2)(alpha), antioxidant defenses, plasma fatty acid status, and clinical markers resulting from short-term antioxidant supplementation.

DESIGN

Forty-six CF patients were randomly assigned to either group A [low dose of supplement (10 mg vitamin E and 500 micro g vitamin A)] or group B [high dose of supplement (200 mg vitamin E, 300 mg vitamin C, 25 mg beta-carotene, 90 micro g Se, and 500 micro g vitamin A)]. Plasma concentrations of 8-iso-PGF(2)(alpha), vitamins E and C, beta-carotene, zinc, selenium, and copper; plasma fatty acid composition; erythrocyte glutathione peroxidase (EC 1.11.1.9) and superoxide dismutase (EC 1.15.1.1) activities; lung function; and dietary intake were measured before and after 8 wk of supplementation.

RESULTS

Antioxidant defenses in group B improved, whereas those in group A did not: in groups B and A, the mean (+/- SEM) changes (Delta) in vitamin E were 10.6 +/- 1.5 and -1.9 +/- 0.9 micro mol/L, respectively (P < 0.001), (Delta)beta-carotene were 0.1 +/- 0.04 and -0.01 +/- 0.02 micro mol/L, respectively (P = 0.007), (Delta)selenium were 0.51 +/- 0.10 and -0.09 +/- 0.04 micro mol/L, respectively (P < 0.001), and (Delta)glutathione peroxidase activity were 1.3 +/- 0.3 and -0.3 +/- 0.6 U/g hemoglobin, respectively (P = 0.016). There were no significant differences between the groups in Delta8-iso-PGF(2)(alpha), (Delta)vitamin C, (Delta)fatty acid composition, (Delta)superoxide dismutase activity, (Delta)lung function, or (Delta)white cell count. Within group B, (Delta)beta-carotene correlated with (Delta)percentage of forced vital capacity (r = 0.586, P = 0.005), (Delta)selenium correlated with (Delta)percentage of forced expiratory volume in 1 s (r = 0.440, P = 0.046), and (Delta)plasma fatty acid concentrations correlated with (Delta)percentage of forced expiratory volume in 1 s (r = 0.583, P = 0.006) and Delta8-iso-PGF(2)(alpha) (r = 0.538, P = 0.010).

CONCLUSIONS

Whereas increased beta-carotene, selenium, and fatty acid concentrations are linked to improved lung function, increased plasma fatty acid concentrations are linked to oxidative stress. If oxidative stress is deemed to be important to the clinical outcome of CF patients, means of reducing oxidative stress while maintaining a high-fat, high-energy diet must be investigated.

Effects of fish oil- and olive oil-rich diets on iron metabolism and oxidative stress in the rat

The objective of the present study was to examine the effects of fish oil (FO)- and olive oil (OO)-rich diets on Fe metabolism and oxidative stress. Rats were fed for 16 weeks with diets containing 50 g lipids/kg; either OO, maize oil (MO) or FO. OO or MO diets contained a standard amount (100 mg/kg) of all-rac-alpha-tocopheryl acetate. FO diets were supplemented with 0, 100 or 200 mg all-rac-alpha-tocopheryl acetate/kg (FO-0, FO-1 or FO-2 diets, respectively). At the end of the feeding period, we measured non-haem Fe stores in liver and spleen, and erythrocyte and reticulocyte count. We also determined antioxidants and products derived from lipid peroxidation in plasma and erythrocytes. Our results showed reduced non-haem Fe stores in rats fed any of the FO diets. Reticulocyte percentage was higher in the rats fed FO-0 and FO-1. Plasma alpha-tocopherol was very low in rats fed the FO-0 diet. Rats fed the FO-1 and FO-2 diets showed higher alpha-tocopherol in plasma than the FO-0 group but lower than the MO or OO groups. We did not observe such differences in the alpha-tocopherol content in erythrocyte membranes. Superoxide dismutase and glutathione peroxidase activities were lower in the erythrocytes of rats fed the FO-0 diet. The products derived from lipid peroxidation were also higher in the FO groups. The administration of FO-rich diets increased lipid peroxidation and affected Fe metabolism. On the other hand, the OO-rich diet did not increase oxidative stress and did not alter Fe metabolism. Based on these results, we conclude that FO supplementation should be advised carefully.

Folate quenches oxidative damage in brains of apolipoprotein E-deficient mice: augmentation by vitamin E

We demonstrate that folate and vitamin E can compensate for the diminished oxidative buffering capacity of brains of apolipoprotein E-deficient mice. Normal and ApoE(tmlUne) homozygous 'knockout' mice were maintained for 1 month on a diet either lacking or supplemented with folate, vitamin E or iron as a pro-oxidant after which brain tissue was harvested and analyzed for for thiobarbituric acid-reactive substances (TBARs) as an index of oxidative damage. Normal mice exhibited no significant difference in TBARs following iron challenge in the presence or absence of vitamin E, folic acid or both. Similarly, ApoE knockout mice exhibited no significant differences following dietary iron challenge in the presence or absence of vitamin E. However, ApoE knockout mice accumulated significantly increased TBARs following iron challenge when folic acid was withheld, and accumulated even more TBARs when both folic acid and vitamin E were withheld. These findings demonstrate that ApoE knockout mice during vitamin deficiency are less capable of buffering the consequences of dietary iron challenge than are normal mice. Since the apolipoprotein E4 allele, which exhibits diminished oxidative buffering capacity, is linked to Alzheimer's disease (AD), these data underscore the possibility that critical nutritional deficiencies may modulate the impact of genetic compromise on neurodegeneration in AD.

Apolipoprotein E deficiency promotes increased oxidative stress and compensatory increases in antioxidants in brain tissue

The epsilon 4 allele of the apolipoprotein E gene (ApoE) is associated with Alzheimer's disease (AD). The extent of oxidative damage in AD brains correlates with the presence of the E4 allele of ApoE, suggesting an association between the ApoE4 genotype and oxygen-mediated damage in AD. We tested this hypothesis by subjecting normal and transgenic mice lacking ApoE to oxidative stress by folate deprivation and/or excess dietary iron. Brain tissue of ApoE-deficient mice displayed increased glutathione and antioxidant levels, consistent with attempts to compensate for the lack of ApoE. Folate deprivation and iron challenge individually increased glutathione and antioxidant levels in both normal and ApoE-deficient brain tissue. However, combined treatment with folate deprivation and dietary iron depleted antioxidant capacity and induced oxidative damage in ApoE-deficient brains despite increased glutathione, indicating an inability to compensate for the lack of ApoE under these conditions. These data support the hypothesis that ApoE deficiency is associated with oxidative damage, and demonstrate a combinatorial influence of genetic predisposition, dietary deficiency, and oxidative stress on oxidative damage relevant to AD.

High dietary iron concentrations enhance the formation of cholesterol oxidation products in the liver of adult rats fed salmon oil with minimal effects on antioxidant status

The aim of this study was to investigate the effect of high dietary iron concentrations on the antioxidant status of rats fed two different types of fat. Four groups of male adult Sprague-Dawley rats were fed diets with adequate (50 mg iron supplemented per kg diet) or high (500 mg iron supplemented per kg diet) iron concentrations with either lard or salmon oil as dietary fat at 100 g/kg for 12 wk. The antioxidant status of the rats was profoundly influenced by the type of fat. Rats fed salmon oil diets had higher concentrations of thiobarbituric acid-reactive substances (TBARS) (P < 0.001), various cholesterol oxidation products (COP) (P < 0.001), total and oxidized glutathione (P < 0.05) and a lower concentration of alpha-tocopherol (P < 0.05) in liver and plasma than rats fed lard diets. The iron concentration of the diet did not influence the concentrations of TBARS, the activities of superoxide dismutase and glutathione peroxidase or the concentration of alpha-tocopherol in plasma or liver. The activity of catalase (P < 0.01) and the concentrations of total, oxidized and reduced glutathione (P < 0.05) in liver were slightly but significantly higher in rats fed high iron diets than in rats fed adequate iron diets, irrespective of the dietary fat. Rats fed the high iron diets with salmon oil, moreover, had higher concentrations of various COP in the liver (P < 0.001) than rats fed adequate iron diets with salmon oil. These results suggest that feeding a high iron diet does not generally affect the antioxidant status of rats but enhances the formation of COP, particularly if the diet is rich in polyunsaturated fatty acids.

Efficacy of vitamin E, phosphatidyl choline, and pyruvate on buffering neuronal degeneration and oxidative stress in cultured cortical neurons and in central nervous tissue of apolipoprotein E-deficient mice

Oxidative stress is a pivotal factor in neuronal degeneration. However, vitamin E was only marginally effective in clinical trials. We examined whether or not a mixture of vitamin E (as alpha-tocopherol), sodium pyruvate and phosphatidyl choline (PC), a mixture that promotes wound healing in non-neuronal systems, would provide neuroprotection beyond that observed with vitamin E alone. Combined treatment with these agents improved survival and neuritic spouting of murine embryonic cortical neurons in culture, and provided neuroprotection against oxidative damage following treatment with hydrogen peroxide. Dietary treatment with these three agents also compensated for the diminished oxidative buffering capacity of brains of apolipoprotein E-deficient mice, while vitamin E alone failed to do so. These data underscore the possibility that critical nutritional deficiencies may modulate the impact of genetic compromise on neurodegeneration.

Effects of dietary lipids on daunomycin-induced nephropathy in mice: comparison between cod liver oil and soybean oil

Although it is well known that dietary lipids affect the course of glomerulonephritis in rats and humans, the precise mechanisms involved have not been fully elucidated. The aim of this study was to investigate the effects of different types of dietary lipids (fish oil and vegetable oil) on daunomycin (DM)-induced nephropathy in mice fed on soybean oil (SO) or cod liver oil (CLO). Urinary protein excretion, serum albumin, creatinine, total cholesterol, and TG were measured, and glomerular histological changes were evaluated. Antioxidant enzymes were also measured, along with the levels of lipid peroxide, GSH, thromboxane (Tx) B2, and 6-keto prostaglandin F1alpha in renal cortical tissue. Dietary CLO significantly reduced urinary albumin excretion and ameliorated the histological changes induced by DM. The increase of tissue lipid peroxide levels seen in SO-fed mice was suppressed in CLO-fed mice, whereas CLO-fed mice showed higher GSH levels than SO-fed mice throughout the experiment. In addition, renal tissue GSH peroxidase activity was significantly higher at 72 h after DM injection in CLO-DM mice than in SO-DM mice. Both renal cortical TxB2 and 6-keto PGF1alpha levels were significantly lower in CLO-DM mice than in SO-DM mice. These results suggest that inhibition of oxidative damage by dietary CLO played an important role in the prevention of DM nephropathy in this mouse model. The effect of CLO was closely associated with the inhibition of Tx synthesis.

Dietary fat source and cholesterol interactions alter plasma lipids and tissue susceptibility to oxidation in spontaneously hypertensive (SHR) and normotensive Wistar Kyoto (WKY) rats

Due to the potential for dietary fat source to alter plasma lipids and tissue antioxidant status, we hypothesized that blends of saturated, n-6 and n-3 fats with cholesterol would affect LDL and tissue susceptibility to in vitro oxidation. The effects of dietary fat blends of butter (B), beef tallow (T), soybean oil (SBO) or menhaden oil (MO) and cholesterol on systolic blood pressure (SBP), plasma lipoproteins and tissue susceptibility to glutathione (GSH) depletion and lipid peroxidation (TBARS) were examined in spontaneously hypertensive (SHR) and Wistar Kyoto (WKY) rats. SBP in SHRs was higher (p < 0.001) than in WKYs at 13-weeks of age but was not altered by dietary fat or cholesterol. LDL- and HDL-cholesterol were greater (p < 0.001) in WKY than SHR. LDL-cholesterol and (VLDL- + LDL-cholesterol)/HDL-cholesterol ratios were reduced in MO vs. B, T and SBO groups. HDL-cholesterol levels tended to be lower and greater in B and MO groups, respectively vs. T and SBO groups. Initial LDL fluorescence was greater (p < 0.001) in high- vs. low-cholesterol groups. The change in LDL fluorescence was reduced (p < 0.001) in high-cholesterol groups, and MO vs. B, T and SBO rats. MO fed rats had reduced (p < 0.001) RBC, heart and liver GSH depletion and reduced (p < 0.01) tissue TBARS and RBC MDA production. In summary, a moderate level of dietary MO did not increase tissue and LDL in vitro oxidizability in SHR and WKY rats. High dietary cholesterol exhibited a protective effect against in vitro oxidation of LDL and selected tissues.

Supplementation of the black rice outer layer fraction to rabbits decreases atherosclerotic plaque formation and increases antioxidant status

The influence of the supplementation of black and white rice outer layer fractions on atherosclerotic plaque formation induced by hypercholesterolemia was investigated in rabbits. Male rabbits (n = 32) were randomly divided into four groups. They were fed nonpurified diet (normal group), a lard (3.5 g/100 g) with high cholesterol (0.5 g/100 g) diet (HC group); the HC diet with 5 g/100 g white rice outer layer fraction (WRF group); or the HC diet with 5 g/100 g black rice outer layer fraction (BRF) for 2 mo. Blood samples were collected for determination of lipid concentration and oxidative and antioxidative status variables, and aortae were taken for the assessment of atherosclerotic plaques. The atherosclerotic plaque area in rabbits fed the BRF diet was 66% lower than that of the HC or WRF rabbits (P < 0.001). Supplementation of the black rice outer layer significantly (P < 0.05) lowered aortic 8-hydroxy-2'-deoxyguanosine (8-OHdG) (-52%, -44%) compared with the WRF or HC diets (P < 0.05). There were no differences in aortic 8-OHdG levels between rabbits fed the BRF and normal diets. The BRF diet significantly (P < 0.05) decreased the malondialdehyde (MDA) level of serum (-37%) and aortic artery (-50%) compared with the WRF diet. There were no differences in the concentrations of serum total cholesterol (TC), LDL cholesterol (LDL-C), HDL-C or the ratio of apoprotein (apo)I/apoB among the HC, WRF and BRF groups. Similarly, there were no differences in the serum vitamin E concentration and erythrocyte and aorta superoxide dismutase (SOD) activities among rabbits fed these diets. The serum concentration of most fatty acids except 18:1 did not differ between the WRF and the BRF groups. We conclude that the inhibition of atherosclerotic plaque formation derived from the black rice outer layer fraction in rabbits might be mediated by antioxidative or anti-inflammatory effects.

Genetic differences in hepatic lipid peroxidation potential and iron levels in mice

Oxidative damage to macromolecules, including lipids, has been hypothesized as a mechanism of aging. One end product of lipid peroxidation, malondialdehyde (MDA), is often quantified as a measure of oxidative damage to lipids. We used a commercial colorimetric assay for MDA (Bioxytech LPO-586, Oxis International, Portland, OR) to measure lipid peroxidation potential in liver tissue from young (2 month) male mice from recombinant inbred (RI) mouse strains from the C57BL/6J (B6)xDBA/2J (D2) series (BXD). The LPO-586 assay (LPO) reliably detected significant differences (P<0.0001) in lipid peroxidation potential between the B6 and D2 parental strains, and yielded a more than two-fold variation across the BXD RI strains. In both B6 and D2 mice, LPO results were greater in old (23 month) mice, with a larger age-related increase in the D2 strain. As the level of iron can influence lipid peroxidation, we also measured hepatic non-heme iron levels in the same strains. Although iron level exhibited a slightly negative overall correlation (r(2)=0.119) with LPO results among the entire group of BXD RI strains, a sub-group with lower LPO values were highly correlated (r(2)=0.704). LPO results were also positively correlated with iron levels from a group of 8 other inbred mouse strains (r(2)=0.563). The BXD RI LPO data were statistically analyzed to nominate quantitaive trait loci (QTL). A single marker, Zfp4, which maps to 55.2 cM on chromosome 8, achieved a significance level of P<0.0006. At least two potentially relevant candidate genes reside close to this chromosomal position. Hepatic lipid peroxidation potential appears to be a strain related trait in mice that is amenable to QTL analysis.

Serum lipid peroxide and alpha-tocopherol concentrations and superoxide dismutase activity in captive bottle-nosed dolphins

OBJECTIVE

To evaluate serum lipid peroxide (LPO) and alpha-tocopherol concentrations and superoxide dismutase (SOD) activity in captive bottle-nosed dolphins and to evaluate effects of storage on production of LPO in various marine fish.

ANIMALS

16 bottle-nosed dolphins.

PROCEDURE

8 dolphins (group A) were fed chub mackerel and herring (high fat) and arabesque greenling and banded blue-sprat (low fat); the other 8 dolphins (group B) were fed chub mackerel and Pacific saury (high fat) and shishamo smelt and Japanese horse mackerel (low fat). Each group had been on these respective diets for 3 years. Serum LPO and alpha-tocopherol concentrations, serum SOD activity, and superoxide production by neutrophils were measured. All types of marine fish were frozen at -20 C for 6 months, and concentrations of LPO were measured at various time points.

RESULTS

Serum LPO concentrations in group-A dolphins were significantly higher than those in group B. Serum alpha-tocopherol concentrations and SOD activity in group A were significantly lower than those in group B. A significant negative correlation was found between serum LPO and alpha-tocopherol concentrations in all 16 dolphins. The LPO concentrations in mackerel and herring fed to group-A dolphins were higher than those of other fish. Concentrations of LPO in herring stored for 3 and 6 months at -20 C were higher than those in herring before freezing and in herring stored for 1 month.

CONCLUSIONS AND CLINICAL RELEVANCE

Serum LPO and alpha-tocopherol concentrations in captive bottle-nosed dolphins may be strongly influenced by high amounts of polyunsaturated fatty acid and LPO found in marine fatty fishes. High concentrations of serum LPO, as found in group-A dolphins, were associated with decreased antioxidative states. Monitoring of serum LPO and alpha-tocopherol concentrations and serum SOD activity may be useful for the management of captive marine mammals.

Oxidation affects the regulation of hepatic lipid synthesis by chylomicron remnants

The effects of native and oxidized chylomicron remnants on lipid synthesis in normal and oxidatively stressed liver cells were investigated using MET murine hepatocytes (MMH cells), a nontransformed mouse hepatocyte cell line that maintains a highly differentiated hepatic phenotype in culture. Lipid synthesis was determined by measuring the incorporation of [(3)H]oleate into cholesteryl ester, triacylglycerol, and phospholipid by the cells. The formation of cholesteryl ester and phospholipid was decreased by chylomicron remnants in a dose-dependent manner, while triacylglycerol synthesis was increased. Exposure of MMH cells to mild oxidative stress by incubation with CuSO(4) (2.5 microM) for 24 h led to significantly increased incorporation of [(3)H]oleate into triacylglycerol and phospholipid, but not cholesteryl ester, in the absence of chylomicron remnants. In the presence of the lipoproteins, however, similar effects to those found in untreated cells were observed. Oxidatively modified chylomicron remnants prepared by incubation with CuSO(4) (10 microM, 18 h, 37 degrees C) did not influence cholesteryl ester or phospholipid synthesis in MMH cells, but had a similar effect to that found with native remnants on triacylglycerol synthesis. These findings show that hepatic lipid metabolism is altered by exposure to mild oxidative stress and by lipids from the diet delivered to the liver in chylomicron remnants, and these effects may play a role in the development of atherosclerosis.

Iron, alpha-tocopherol, oxidative damage and micronucleus formation in rat splenocytes

The influence of low and high alpha-tocopherol diets in concert with a high polyunsaturated fat content and a modest increase in dietary iron has been studied. Iron supplementation at 5 times the recommended dietary level was not associated with any increased sensitivity of splenocytes to any of several oxidative challenges ex vivo. Despite the significantly higher alpha-tocopherol concentrations in plasma and liver in animals supplemented with this vitamin, there was no apparent protection against oxidative genotoxicity as judged by the formation of micronuclei in splenocytes subjected to oxidative stress ex vivo. These results add to the accumulating evidence that vitamin E supplementation has little effect against oxidative genomic damage, at least as demonstrated by an increase in micronucleus frequency.

IL-4 plays a crucial role in regulating oxidative damage in the liver during schistosomiasis

Liver enlargement and hepatocyte proliferation, normal responses in wild-type (WT) mice infected with the parasitic helminth Schistosoma mansoni, were found to be severely impaired in infected IL-4(-/-) mice. Compared with WT mice, increased levels of O(2)(-), NO, and the more highly reactive ONOO(-) were detected in the liver and produced by lesional cells isolated from liver granulomas of infected IL-4(-/-) mice. Concurrently, antioxidant defenses in the liver, specifically catalase levels, diminished dramatically during the course of infection in these animals. This contrasted to the situation in infected WT mice, where catalase levels remained as high as those in normal mice. Actual levels of reactive oxygen and nitrogen intermediates in the livers of infected IL-4(-/-) animals are thus likely to be considerably higher than those in the livers of infected WT mice. To determine whether these changes contributed to the development of the more severe disease that characterizes infection in the IL-4(-/-) animals, we treated infected IL-4(-/-) mice with uric acid, a potent scavenger of ONOO(-). This resulted in significantly increased hepatocyte proliferation, decreased morbidity, and prolonged survival. Taken together, these data indicate that IL-4 is playing a protective role during schistosomiasis by controlling the tight regulation of the generation of reactive oxygen and nitrogen intermediates in the liver.

Long-term high protein intake does not increase oxidative stress in rats

The maximum dietary protein intake that does not cause adverse effects in a healthy population is uncertain. We tested whether a high protein intake enhances oxidative stress. Adult rats were adapted to different casein-based diets containing either an adequate (13.8%; AP), medium (25.7%; MP), or high (51.3%; HP) level of crude protein; a fourth group received a HP diet but no RRR-alpha-tocopherol acetate (HP-toc). After 15 wk of feeding, plasma protein carbonyl concentration, liver lipid peroxide levels [thiobarbituric acid-reacting substances (TBARS)], reduced glutathione (GSH) status and leucine kinetics ([1-(13)C]leucine) were measured. Higher concentrations of protein carbonyls and TBARS were found in rats fed the AP and the HP-toc diets compared with those fed the MP and HP diets (P: < 0.05). GSH concentrations in plasma did not differ but total blood GSH concentrations were significantly (P: < 0.05) lower in rats fed the HP-toc diet compared with those fed the AP, MP and HP diets. Liver GSH concentrations were significantly (P: < 0.01) lower in rats fed the AP diet compared with the other groups. Rates of postabsorptive leucine oxidation (LeuOX) and flux (Q(Leu)) were positively correlated with the dietary protein level (for AP, MP, and HP, respectively: LeuOX, 74.9 +/- 28.5, 109 +/- 35.2, 142.3 +/- 38.4 micromol/(kg. h); Q(Leu), 425 +/- 102, 483 +/- 82, 505 +/- 80 micromol/(kg. h). Only HP-toc resulted in a significantly greater protein breakdown (PB(Leu)) and Q(Leu). No difference was seen in nonoxidative leucine disposal. Long-term intake of high protein diets did not increase variables of oxidative stress, in contrast to our initial hypothesis. An unexpected finding was that adequate protein feeding (AP) may in fact induce oxidative stress.

Iron, alpha-tocopherol, oxidative damage and micronucleus formation in rat splenocytes

The influence of low and high alpha-tocopherol diets in concert with a high polyunsaturated fat content and a modest increase in dietary iron has been studied. Iron supplementation at five times the recommended dietary level was not associated with any increased sensitivity of the splenocytes to any of the oxidative challenges. Despite the significantly higher alpha-tocopherol concentrations in the plasma and liver of animals supplemented with this vitamin, there was no apparent protection against oxidative genotoxicity, as judged by the formation of micronuclei in splenocytes subjected to oxidative stress ex vivo. These results add to the evidence that vitamin E supplementation has little effect against oxidative genomic damage, at least as demonstrated by an increase in micronucleus frequency.

Effects of dietary n-3 fatty acids on contractility, Na+ and K+ currents in a rat cardiomyocyte model of arrhythmia

The n-3 polyunsaturated fatty acids (PUFAs) have been reported to prevent ventricular fibrillation in human clinical studies and in studies involving experimental animals and isolated cardiomyocytes. This study aimed to determine whether dietary n-3 PUFAs could prevent isoproterenol and free radical-induced arrhythmic (asynchronous) contractile activity in adult rat cardiomyocytes and whether whole-cell Na(+) and K(+) currents measured by patch-clamp techniques were affected. Dietary supplementation with fish oil for 3 weeks significantly increased the proportion of total n-3 PUFAs in ventricular membrane phospholipids compared with saturated fat supplementation (18.8 +/- 0.6% vs. 8.1 +/- 1.0%, respectively). Cardiomyocytes from the fish oil group were less susceptible to isoproterenol-induced asynchronous contractile activity than were those from the saturated fat group [EC(50) values: 892 +/- 130 nM, n = 6 and 347 +/- 91 nM, n = 6 (P < 0.05), respectively]. Fish oil supplementation also prolonged the time taken to develop asynchronous contractile activity induced by superoxide and hydrogen peroxide. The voltage dependence of inactivation of Na(+) currents were significantly altered (-73.5 +/- 1.2 mV, n = 5 vs. -76.7 +/- 0.7 mV, n = 5, P < 0.05, for saturated fat and fish oil treated groups, respectively). The voltage dependence of activation of Na(+) and K(+) currents was not significantly affected by the dietary fish oil treatment. These results demonstrate the antiarrhythmic effects of dietary fish oil in a cardiomyocyte model of arrhythmia.

Protein oxidation in human stratum corneum: susceptibility of keratins to oxidation in vitro and presence of a keratin oxidation gradient in vivo

The stratum corneum is located at the interface between body and environment and thus is constantly exposed to a pro-oxidative environment. Previously, we have demonstrated that stratum corneum lipids are targets of oxidative stress induced by ozone and by ultraviolet A and B exposure. Here, we employed an immunoblotting technique to detect protein oxidation in human stratum corneum obtained by tape stripping. After lysis, protein carbonyl groups were measured by derivatization with dinitrophenylhydrazine, separation by sodium dodecylsulfate-polyacrylamide gel electrophoresis, and immunoblotting using antibodies against dinitrophenyl groups. Keratin 10, identified by use of specific antibodies and by microsequencing, was demonstrated in vitro to be oxidizable by ultraviolet A irradiation, hypochlorite, and benzoyl peroxide. In vivo, a keratin 10 oxidation gradient with low levels in the lower stratum corneum layers, and about 3-fold higher contents of carbonyl groups towards the outer layers was demonstrated in forehead stratum corneum of healthy volunteers (n = 6). As protein oxidation can be associated with an increased susceptibility to proteases, this finding may be important for better understanding the process of desquamation.

Cholesterol-independent endothelial dysfunction in virgin and pregnant rats fed a diet high in saturated fat

1. Western diets high in saturated fat are associated with an increased incidence of cardiovascular diseases. In this study we have evaluated vascular endothelial function and oxidative stress in virgin rats fed a normal (VC) or high in saturated fat diet (VHF) (20 % lard and corn oil w/w) from weaning until adulthood, and throughout subsequent pregnancy (PC and PHF, respectively). 2. The saturated fat diet was associated with enhanced noradrenaline sensitivity in small mesenteric arteries from VHF rats (VHF vs. VC, P < 0.05) and blunted endothelium-dependent relaxation in VHF and PHF rats (VHF vs. VC, P < 0.001; PHF vs. PC, P < 0.05). Endothelial dysfunction was attributable to a reduced nitric oxide component of relaxation in VHF rats, and blunted prostacyclin and endothelium-derived hyperpolarizing factor components in PHF rats. 3. Other than plasma cholesterol, which was reduced in VHF and PHF rats, plasma lipids were normal. Fasting plasma insulin and glucose concentrations were raised in VHF rats (P < 0.05) and the plasma marker of oxidative stress, 8-iso PGF2alpha, was increased in PHF animals (P < 0.01). 4. These findings suggest that endothelial dysfunction induced by a saturated fat diet is cholesterol independent and likely to be of different mechanistic origin in virgin and pregnant rats.

Effect of dietary vitamin E on antioxidant status and antioxidant enzyme activities in Sprague-Dawley rats

The effect of dietary vitamin E on plasma, red blood cells (RBC), hepatic antioxidant status, and antioxidant enzyme activities was investigated. Three groups of six Sprague-Dawley rats were fed 0, 100, or 1,500 ppm vitamin E for eight weeks. Plasma alpha-tocopherol level was increased significantly by increasing dietary vitamin E (p < 0.05). Plasma lipid peroxidation (thiobarbituric acid-reactive substances) stimulation by 1 mM t-butyl hydroperoxide was correlated with dietary vitamin E level and was significantly greater in rats fed no vitamin E than in rats fed 100 or 1,500 ppm vitamin E (p < 0.05). RBC reduced glutathione (GSH) level was positively correlated with dietary vitamin E and was significantly greater in rats fed 1,500 ppm vitamin E than in rats fed 0 or 100 ppm vitamin E (p < 0.05). RBC oxidized glutathione was negatively correlated with dietary vitamin E. GSH redox status was expressed as the GSH-to-total GSH ratio; the ratio was also positively correlated with dietary vitamin E and was significantly greater in rats fed 1,500 ppm vitamin E than in rats fed no vitamin E (p < 0.05). For antioxidant enzymes, superoxide dismutase activity in hepatic cytosolic fraction was significantly greater in rats fed 1,500 ppm vitamin E than in rats fed 100 ppm vitamin E. Hepatic GSH reductase activity was significantly greater in rats fed 100 ppm vitamin E than in rats fed no vitamin E (p < 0.05). Dietary vitamin E had no effect on plasma vitamin C and protein thiol levels. In the systems studied, results indicated that dietary vitamin E selectively influences plasma vitamin E level, RBC GSH status, and hepatic cytosolic superoxide dismutase and GSH reductase activities.

Influence of dietary fat and vitamin E on antioxidant status of muscles of turkey

The aim of this study was to better understand the effects of more or less unsaturated fat source (tallow/soy oil/rapeseed oil) and/or vitamin E dietary supplementation (200 ppm) on the antioxidant status (at day 1 post-mortem) of turkey muscles [pectoralis major (Pm) and sartorius (S)]. More particularly, when turkeys were fed tallow, supplementation was sufficient to improve significantly the vitamin E status. Feeding rapeseed oil increased the antioxidant enzyme (AOE) activities (catalase, superoxide dismutase, glutathion reductase), glutathione concentration, and value from the benzoic acid test. Dietary soy oil increased glutathione peroxidase activity, compared to other dietary fat sources. With tallow, most of AOE activities were lower than with rapeseed or soy oil. Whatever the feeding mode, vitamin E supplementation did not affect the AOE activities, glutathione concentration, or values from the benzoic acid test. AOE activities were always higher in the oxidative S muscle than in the glycolytic Pm muscle. After feeding tallow, 9 days of storage increased TBA-RS and carbonyl contents, whereas the activity of many antioxidant enzymes and the total antioxidant activity (TEAC test and benzoic acid test) decreased.

Olive oil supplemented with vitamin E affects mitochondrial coenzyme Q levels in liver of rats after an oxidative stress induced by adriamycin

In this study we have evaluated the supplementation of olive oil with vitamin E on coenzyme Q concentration and lipid peroxidation in rat liver mitochondrial membranes. Four groups of rats were fed on virgin olive, olive plus 200 mg/kg of vitamin E or sunflower oils as lipid dietary source. To provoke an oxidative stress rats were administered intraperitoneally 10 mg/kg/day of adriamycin the last two days of the experiment. Animals fed on olive oil plus vitamin E had significantly higher coenzyme Q and vitamin E levels but a lower mitochondrial hydroperoxide concentration than rats fed on olive oil. Retinol levels were not affected, by either different diets or adriamycin treatment. In conclusion, an increase in coenzyme Q and alpha-tocopherol in these membranes can be a basis for protection against oxidation and improvement in antioxidant capacity.

Phytic acid inhibits free radical formation in vitro but does not affect liver oxidant or antioxidant status in growing rats

The objective of this study was to determine the effects of phytic acid on free radical generation in vitro and in growing rats. Electron spin resonance spectroscopy studies using 5, 5-dimethyl-1-pyrroline-N-oxide (DMPO) as a spin trap indicate a complete inhibition of hydroxyl radical formation via the iron-catalyzed Fenton reaction at molar phytic acid/iron ratios >5. However, phytic acid had no scavenging effect on superoxide radicals generated in the xanthine/xanthine oxidase reaction. For the in vivo study, male growing albino rats were fed purified diets based on casein, cornstarch and vitamin E-stripped corn oil differing in the concentration of iron (30 or 300 mg/kg), phytic acid (0 or 10 g/kg) and dl-alpha-tocopheryl acetate (0 or 50 mg/kg). At marginal dietary iron supply, phytic acid supplementation reduced apparent Fe absorption, thereby decreasing liver Fe concentration. Dietary iron and phytate had no effect on the level of hepatic alpha-tocopherol, reduced glutathione, thiobarbituric acid-reactive substances and protein carbonyls. The concentration of thiobarbituric acid-reactive substances and protein carbonyls in the liver decreased as dietary vitamin E was increased from 0 to 50 mg/kg diet. The results obtained provide evidence for antioxidant properties of phytic acid under in vitro conditions. However, neither phytic acid nor iron had any significant effect on liver oxidant or antioxidant status in vivo in growing rats.