Dietary supplementation with <Emphasis Type="Italic">N</Emphasis>-acetylcysteine, α-tocopherol and α-lipoic acid prevents age related decline in Na<Superscript>+</Superscript>,K<Superscript>+</Superscript>-ATPase activity and associated peroxidative damage in rat brain synaptosomes

This study has shown that in aged rat brain (22–24 months) crude synaptosomes in comparison to that in young animals (4–6 months), a striking decrease in the activity of Na⁺,K⁺-ATPase occurs along with decreased K _m and V _max but without any change in enzyme content as seen by immunoblotting. This is associated with an accumulation of peroxidative damage products in aged brain. When rats are given antioxidant supplementation in the diet with a combination of N-acetylcysteine, α-tocopherol and α-lipoic acid daily from 18 months onwards and sacrificed at 22–24 months for experimentation, the age associated decrease of Na⁺,K⁺-ATPase activity, alterations of its kinetic parameters and accumulation of peroxidative damage products in brain synaptosomes are prevented nearly completely. Because of the critical importance of Na⁺,K⁺-ATPase in neuronal functions, the results of this study may be of potential implications in controlling age-related functional deficits of the brain.     

The effect of carnosine treatment on prooxidant–antioxidant balance in liver,heart and brain tissues of male aged rats

Carnosine (β-alanyl-l-histidine) is a dipeptide with antioxidant properties. Oxidative damage by free radicals is one of the mechanisms underlying the aging process. This study was done to investigate the effects of carnosine treatment on lipid peroxidation and antioxidant status of liver, heart, brain in male young and aged rats. At the initiation of study, young and aged rats were 5 and 22 months old, respectively. Carnosine (250 mg/kg, daily, i.p.) was administered for 1 month to rats. At the end of this period, malondialdehyde (MDA) and diene conjugate (DC) and protein carbonyl (PC) levels, glutathione (GSH), vitamin E and vitamin C levels and Cu,Zn-superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and glutathione transferase (GST) activities were determined in tissues of carnosine-treated young and old rats. Liver and heart, but not brain MDA and DC levels increased significantly in aged rats as compared to young rats. Liver PC levels were also significantly elevated. Significant decreases in GSH and vitamin C levels and SOD activities were detected in liver of aged rats, but vitamin E levels and GSH-Px and GST activities remained unchanged. Non-enzymatic and enzymatic antioxidants did not change in heart and brain of aged rats. Carnosine treatment decreased high MDA, DC and PC levels and caused significant increases in vitamin E level and SOD activity in the liver of aged rats. There were no changes in non-enzymatic and enzymatic antioxidants in the heart and brain of carnosine-treated aged rats. In conclusion, carnosine treatment was found to be useful in the decrease of age-related oxidative stress in the liver.     

Dietary supplementation with N-acetyl cysteine, α-tocopherol and α-lipoic acid reduces the extent of oxidative stress and proinflammatory state in aged rat brain

The present study has attempted to understand how oxidative stress contributes to the development of proinflammatory state in the brain during aging. Three groups of rats have been used in this study: young (4–6?months, Group I), aged (22–24?months, Group II) and aged with dietary antioxidant supplementation (Group III). The antioxidants were given daily from 18?months onwards in the form of a combination of N-acetyl cysteine (50?mg/100?g body weight), α-lipoic acid (3?mg/100?g body weight), and α-tocopherol (1.5?mg/100?g body weight) till the animals were used for the experiments between 22 and 24?months. Several measurements have been made to evaluate the ROS (reactive oxygen species) production rate, the levels of proinflammatory cytokines (IL-1β, IL-6 and TNF-α) and the activation status of NF-κβ (p65 subunit) in brain of the three groups of rats under the study. Our results reveal that brain aging is accompanied with a significant increase in NADPH oxidase activity and mitochondrial ROS production, a distinct elevation of IL-1β, IL-6 and TNF-α levels along with increased nuclear translocation of NF-κβ (p65 subunit) and all these phenomena are partially but significantly prevented by the long-term dietary antioxidant treatment. The results imply that chronic dietary antioxidants by preventing oxidative stress and proinflammatory state may produce beneficial effects against multiple age-related deficits of the brain.     

Homocysteine Induces Oxidative–Nitrative Stress in Heart of Rats: Prevention by Folic Acid

Hyperhomocysteinemia is a risk factor for cardiovascular disease, stroke, and thrombosis; however, the mechanisms by which homocysteine triggers these dysfunctions are not fully understood. In the present study, we investigated the effect of chronic hyperhomocysteinemia on some parameters of oxidative stress, namely thiobarbituric acid reactive substances, an index of lipid peroxidation, 2′,7′-dichlorofluorescein (H₂DCF) oxidation, activities of antioxidant enzymes named superoxide dismutase and catalase, as well as nitrite levels in heart of young rats. We also evaluated the effect of folic acid on biochemical alterations elicited by hyperhomocysteinemia. Wistar rats received daily subcutaneous injection of homocysteine (0.3–0.6 μmol/g body weight) and/or folic acid (0.011 μmol/g body weight) from their 6th to the 28th day of life. Controls and treated rats were killed 1 h and/or 12 h after the last injection. Results showed that chronic homocysteine administration increases lipid peroxidation and reactive species production and decreases enzymatic antioxidant defenses and nitrite levels in the heart of young rats killed 1 h, but not 12 h after the last injection of homocysteine. Folic acid concurrent administration prevented homocysteine effects probable by its antioxidant properties. Our data indicate that oxidative stress is elicited by chronic hyperhomocystenemia, a mechanism that may contribute, at least in part, to the cardiovascular alterations characteristic of hyperhomocysteinemic patients. If confirmed in human beings, our results could propose that the supplementation of folic acid can be used as an adjuvant therapy in cardiovascular alterations caused by homocysteine.     

Ganoderma lucidum (Fr.) P. Karst enhances activities of heart mitochondrial enzymes and respiratory chain complexes in the aged rat

Aging is associated with increased oxidative damage at multiple cellular levels, decline in cellular energy production and enhanced free radical status. The effect of the medicinal mushroom, Ganoderma lucidum on the activities of tricarboxylic acid (Krebs) cycle enzymes and mitochondrial complexes I–IV of the electron transport chain in aged rats were investigated. The activity of Krebs cycle enzymes, isocitrate dehydrogenase, α-ketoglutarate dehydrogenase, succinate dehydrogenase, and malate dehydrogenase as well as mitochondrial complexes I, II, III, and IV were determined in heart of aged male Wistar rats orally administrated with 70% ethanolic extract (50 and 250 mg/kg) of G. lucidum. DL-α-lipoic acid (100 mg/kg) was taken as the positive control. Administration of the G. lucidum, once daily for 15 days, was significantly (P < 0.05) effective to enhance the Krebs cycle dehydrogenases, and mitochondrial electron transport chain complex IV activities in aged rats. The profound activity of the extract can be correlated to the significant antioxidant property of G. lucidum. The results of the study revealed that G. lucidum is effective to ameliorate the age associated decline of cellular energy status.     

Alterations in oxidative stress scavenger system in aging rat brain and lymphocytes

There is a large body of evidence indicating an age-related increase in the rate of mitochondrial O₂ ⁻ and H₂O₂ generation and huge amounts of oxidative damage leading to several neurodegenerative disorders, perhaps due to an imbalance between free radical generation and anti-oxidant defense system. The aim of the present study was to elucidate the effect of aging on free radical scavenger system profile in rat brain and lymphocytes. The enzyme activities of γ-GCS, GR, GPx, γ-GTP, GST, catalase, and SOD as well as GSH content were assayed from discrete brain areas viz., CH, CB,BS and DC along with lymphocytes from four different age group rats, namely, 1-month-oldyoung rats, 3–4-month-old young adults, 12-month-old adults and 24-month-old aged rats. Significant decline was observed in all the enzyme activities in 12- and 24-month-old rats as compared to 3–4-month-old young adult rats and also, 1-month-old rats showed lower levels of enzyme activities as compared to 3–4-month-old rats. The maximum scavenger system activity was found in the young adult rats (3–4 months) as compared to the remaining age groups. Lymphocytes and brain showed a parallel pattern of age-related alterations in the free radical scavenger system components. The analysis of such alterations is important in ultimately determining the basis of neuronal dysfunction associated with aging and also defining the nature of these changes may help to develop therapeutic means to cure not only elderly but also individuals suffering from certain organic or psychiatric disorders. This revised version was published online in July 2006 with corrections to the Cover Date.     

Age-dependent alterations in mitochondrial enzymes in cortex,striatum and hippocampus of rat brain – potential role of L-Carnitine

Mitochondria link the energy – releasing activities of electron transport and proton pumping with the energy conserving process of oxidative phosphorylation to form ATP. A declined mitochondrial performance has been generally observed during aging. In the present investigation, the activities of tricarboxylic acid cycle enzymes such as isocitrate, -ketoglutarate, succinate and malate dehydrogenases and electron transport complexes I–IV were measured in mitochondria isolated from brain regions like cortex, striatum and hippocampus of young and aged rats before and after L-Carnitine supplementation. All the three brain regions of aged rats showed decreased activities of isocitrate, -ketoglutarate and succinate dehydrogenases, complexes I and IV when compared to control young rats. Striatum seems to be the most susceptible region when compared to hippocampus and cortex. L-Carnitine supplementation to aged rats reversed the activities of these enzymes to near normal whereas treatment to young rats did not show any significant alterations. These results confirm that L-Carnitine can alleviate the age-associated decline in the metabolic efficiency of mitochondria in all three brain regions under investigation.This revised version was published online in October 2005 with corrections to the Cover Date.     

Hormonal regulation of pro-inflammatory and lipid peroxidation processes in liver of old ovariectomized female rats

There is now a large body of evidence suggesting that the decline in ovarian function with menopause is associated with spontaneous increases in pro-inflammatory cytokines. On the other hand, oxidative stress has been implicated in the pathogenesis of several alterations due to menopause, and can arise through the increased production of lipid peroxides (LPO) and/or a deficiency of antioxidant defense. The aim of the present study was to investigate the effect of aging and ovariectomy on various physiological parameters related to inflammation and oxidative stress in livers obtained from old female rats and the influence of chronic exogenous administration of estrogens, phytoestrogens and growth hormone on these. Thirty-six female Wistar rats of 22 months of age were used in the present study. Twelve of them remained intact, and the other 24 had been ovariectomized at 12 months of age. Intact animals were divided into two groups and treated for 10 weeks with GH or saline, and ovariectomized animals were divided into four groups and treated for the same time with GH, estrogens, phytoestrogens or saline. A group of 2 month old intact female rats was used as young control. Protein expression of iNOS, HO-1, IL-6, TNFα, and IL-1β were determined by Western blot analysis. The levels of NO _x , LPO, TNFα, IL-1β, IL-6 and IL-10 were determined in different fractions of the liver. Levels of LPO in the liver homogenates as well as iNOS protein expression and NO _x levels were increased in old rats as compared to young animals; this effect was more evident in ovariectomized animals. Pro-inflammatory cytokines TNF-α, IL-1β and IL-6 were significantly increased and anti-inflammatory IL-10 decreased during ageing and after ovariectomy. Aging also significantly increased expression of HO-1 protein and ovariectomized rats showed an additional increase. Hormonal administration to the ovariectomized groups decreased NO _x , LPO levels and pro-inflammatory cytokines as compared with untreated rats. Significant rise in IL-10 and reductions in the iNOS, IL-6, TNFα and IL-1β proteins expression were also found. Oxidative stress and inflammation induced during aging in the liver are more marked in castrated than in intact old females. Administration of the different hormonal replacement therapies was able to inhibit the induction of pro-inflammatory cytokines and iNOS, decreased the levels of oxidative stress markers and had therapeutic potential in the prevention of liver injury.     

Proline impairs energy metabolism in cerebral cortex of young rats

In the present study we investigated the effect of acute hyperprolinemia on some parameters of energy metabolism, including the activities of succinate dehydrogenase and cytocrome c oxidase and ¹⁴CO₂ production from glucose and acetate in cerebral cortex of young rats. Lipid peroxidation determined by the levels of thiobarbituric acid-reactive substances, as well as the influence of the antioxidants α-tocopherol plus ascorbic acid on the effects elicited by Pro on enzyme activities and on the lipid peroxidation were also evaluated. Wistar rats of 12 and 29 days of life received one subcutaneous injection of saline or proline (12.8 or 18.2 μmol/g body weight, respectively) and were sacrificed 1 h later. In another set of experiments, 5- and 22-day-old rats were pretreated for a week with daily intraperitoneal administration of α-tocopherol (40 mg/kg) plus ascorbic acid (100 mg/kg) or saline. Twelve hours after the last injection, rats received one injection of proline or saline and were sacrificed 1 h later. Results showed that acute administration of proline significantly reduced cytochrome c oxidase activity and increased succinate dehydrogenase activity and ¹⁴CO₂ production in cerebral cortex, suggesting that Pro might disrupt energy metabolism in brain of young rats. In addition, proline administration increased the thiobarbituric acid-reactive substances levels, which were prevented by antioxidants. These findings suggest that mitochondrial dysfunction and oxidative stress may be important contributors to the neurological dysfunction observed in some hyperprolinemic patients and that treatment with antioxidants may be beneficial in this pathology.     

The influence of L-carnitine suplementation on the antioxidative abilities of serum and the central nervous system of ethanol-induced rats

The brain is exceptionally susceptible to oxidative stress that may be caused by xenobiotics such as ethanol. Alcohol metabolism is accompanied by enhanced free radical formation and a decrease in antioxidant abilities. However, L-carnitine appears to have antioxidant properties and the ability to regulate ethanol metabolism. The present study was designed to estimate the effect of L-carnitine on the antioxidant capacity of the rat brain and blood serum. For 5 weeks during the study, L-carnitine was given to rats in the amount of 1.5 g/1 l of drinking water, and from the second week the rats were intragastrically treated with ethanol. A significant decrease in the activity of antioxidant enzymes (Cu,Zn-SOD, GSH-Px, GSSG-R and CAT) and in the level of non-enzymatic antioxidants (vitamin C, E, A, GSH and GSH-t) as well as a significant increase in the level of GSSG in the brain and blood serum of ethanol intoxicated rats have been demonstrated. It has also been shown that alcohol caused a significant increase in the level of lipid peroxidation products—lipid hydroperoxides, malondialdehyde and 4-hydroxynonenal—and an increase in dityrosine, as well as a decrease in tryptophan—markers of protein oxidative modifications. The administration of L-carnitine to ethanol intoxicated rats partially normalized the activity of the examined enzymes and the level of the above non-enzymatic antioxidants. Moreover, L-carnitine significantly protects lipids and proteins against oxidative modifications. In conclusion, it has been proved that L-carnitine protects rat brain and blood serum against oxidative stress formation and it is possible that this small molecular amine has a similar beneficial effect on the human CNS.     

Age-related changes in the rat brain mitochondrial antioxidative enzyme ratios: Modulation by melatonin

Oxidative stress is an important factor for aging. The antioxidative enzymes glutathione peroxidase (GPx), glutathione reductase (GRd) and superoxide dismutase (SOD) play a crucial role protecting the organism against the age-dependent oxidative stress. Glutathione (GSH) is present in nearly all living cells. GSH is one of the main antioxidants in the cell and it serves several physiological functions. Our purpose was to evaluate the age-related changes in mitochondrial GPx, GRd and SOD activities, and mitochondrial GSH pool in the brains of young (3months) and aged rats (24months). We also investigated whether melatonin administration influences these brain mitochondrial enzyme activities and GSH levels in young and aged rats. The results showed that GPx activity increased with age, whereas melatonin treatment decreased GPx activity in the aged rats at levels similar to those in young and young+melatonin groups. The activities of GRd and SOD, however, did not change with age. But, melatonin treatment increased SOD activity in the aged rats. GSH levels, which also increased with age, were not modified by melatonin treatment. The reduction in the SOD/GPx and GR/GPx ratios with age was prevented by melatonin administration. Together, our results suggest that the age-related oxidative stress in rat brain mitochondria is more apparent when the antioxidant enzyme ratios are analyzed instead of their absolute values. The antioxidative effects of melatonin were also supported by the recovery of the enzyme ratios during aging.     

High-Dose Testosterone Propionate Treatment Reverses the Effects of Endurance Training on Myocardial Antioxidant Defenses in Adolescent Male Rats

This study was aimed at evaluation of changes in activities of selected antioxidant enzymes (superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase) and contents of key nonenzymatic antioxidants (glutathione, protein thiol groups, and α- and γ-tocopherols) in the left heart ventricle of young male Wistar rats subjected to endurance training (treadmill running, 1 h daily, 5 days a week, for 6 weeks) or/and testosterone propionate treatment (8 or 80 mg/kg body weight, intramuscularly, once a week, for 6 weeks) during adolescence. The training alone increased the activities of key antioxidant enzymes, but lowered the pool of nonenzymatic antioxidants and enhanced myocardial oxidative stress as evidenced by elevation of the lipid peroxidation biomarker malondialdehyde. The lower-dose testosterone treatment showed mixed effects on the individual components of the antioxidant defense system, but markedly enhanced lipid peroxidation. The higher-dose testosterone treatment decreased the activities of the antioxidant enzymes, lowered the contents of the nonenzymatic antioxidants, except for that of γ-tocopherol, reversed the effect of endurance training on the antioxidant enzymes activities, and enhanced lipid peroxidation more than the lower-dose treatment. These data demonstrate the potential risk to cardiac health from exogenous androgen use, either alone or in combination with endurance training, in adolescents.     

Creatine plus pyruvate supplementation prevents oxidative stress and phosphotransfer network disturbances in the brain of rats subjected to chemically-induced phenylketonuria

Phenylketonuria (PKU) is the most common inborn error of amino acid metabolism. Usually diagnosed within the first month of birth, it is essential that the patient strictly follow the dietary restriction of natural protein intake. Otherwise, PKU impacts the development of the brain severely and may result in microcephaly, epilepsy, motor deficits, intellectual disability, and psychiatric and behavioral disorders. The neuropathology associated with PKU includes defects of myelination, insufficient synthesis of monoamine neurotransmitters, amino acid imbalance across the blood-brain barrier, and involves intermediary metabolic pathways supporting energy homeostasis and antioxidant defenses in the brain. Considering that the production of reactive oxygen species (ROS) is inherent to energy metabolism, we investigated the association of creatine+pyruvate (Cr?+?Pyr), both energy substrates with antioxidants properties, as a possible treatment to mitigate oxidative stress and phosphotransfer network impairment elicited in the brain of young Wistar rats by chemically-induced PKU. We induced PKU through the administration of α-methyl-L-phenylalanine and phenylalanine for 7 days, with and without Cr?+?Pyr supplementation, until postpartum day 14. The cotreatment with Cr?+?Pyr administered concurrently with PKU induction prevented ROS formation and part of the alterations observed in antioxidants defenses and phosphotransfer network enzymes in the cerebral cortex, hippocampus, and cerebellum. If such prevention also occurs in PKU patients, supplementing the phenylalanine-restricted diet with antioxidants and energetic substrates might be beneficial to these patients.

     

Age- and diabetes-induced regulation of oxidative protein modification in rat brain and peripheral tissues: Consequences of treatment with antioxidant pyridoindole

The increased glyco- and lipo-oxidation events are considered one of the major factors in the accumulation of non-functional damaged proteins, and the antioxidants may inhibit extensive protein modification and nitrosylated protein levels, enhancing the oxidative damage at the cellular levels in aging and diabetes. Because of its central role in the pathogenesis of age-dependent and diabetes-mediated functional decline, we compared the levels of oxidatively modified protein markers, namely AGEs (Advanced Glycation End-protein adducts), 4-HNE (4-hydroxy-nonenal-histidine) and 3-NT (3-nitrotyrosine), in different tissues of young and old rats. Separately, these three oxidative stress parameters were explored in old rats subjected to experimentally induced diabetes and following a long-term treatment with a novel synthetic pyridoindole antioxidant derived from stobadine-SMe1EC2 (2-ethoxycarbonyl-8-methoxy-2,3,4,4a,5,9b-hexahydro-1H-pyrido[4,3-b]indolinium dichloride). Diabetes induced by streptozotocin injection in rats aged 13–15 months, and SMe1EC2 treatment was applied during 4 months to aged diabetic rats. AGEs and 4-HNE levels were significantly elevated in brain, ventricle and kidney, but not in lens and liver of aged rats when compared with young rats. Diabetes propagated ageing-induced increase in AGEs and 4-HNE in brain, ventricle and kidney, and raised significantly lens and liver AGEs and 4-HNE levels in aged rats. In aged diabetic rats, SMe1EC2 protected only the kidney against increase in AGEs, and inhibited significantly 4-HNE levels in brain, kidney, liver and lens that were observed more pronounced in lens. 3-NT was significantly increased in brain of aged rats and in kidney, lens and ventricle of aged diabetic rats, while SMe1EC2 has no protective effect on 3-NT increase. Results demonstrate that (1) the responsiveness of different tissue proteins to glyco-lipo-oxidative and nitrosative stress in the course of normal aging was miscellaneous. (2) Diabetes is a major factor contributing to accelerated aging. (3) SMe1EC2 selectively inhibited the generation of oxidatively modified proteins, only in a limited number of tissues.     

Effect of DL-alpha-lipoic acid on the status of lipid peroxidation and antioxidant enzymes in various brain regions of aged rats

The effect of DL-alpha-lipoic acid on lipid peroxidation and antioxidant enzymes were evaluated in various brain regions of young and aged rats. Lipoate contents of discrete brain regions were also measured. In aged rats, the activities of superoxide dismutase, glutathione peroxidase, glutathione reductase and glucose-6-phosphate dehydrogenase were low whereas thiobarbituric acid reactive substances were found to be high. Catalase activity in various brain regions was little altered in aged rats. Lipoic acid an antioxidant was administered intraperitoneally (100mg/kg body weight per day) for 7 and 14 days. Lipoate administered aged rats showed a duration dependent reduction in the level of lipid peroxidation and elevation in the activities of antioxidant enzymes. There was a rise in the level of lipoate in aged rats after supplementation of lipoate in all the brain regions examined. From our results we conclude that lipoate supplementation had a beneficial effect in both preventing and reversing abnormalities in ageing brain. This beneficial effect was associated with normalization of lipid peroxidation and partial restoration in the activities of various enzymatic antioxidants suggesting that lipoate supplementation could improve brain antioxidant functions in the elderly.     

Effect of dietary supplementation with the pyridoindole antioxidant stobadine on antioxidant state and ultrastructure of diabetic rat myocardium

Consistent with the postulated role of oxidative stress in the etiology of late diabetic complications, pharmacological interventions based on biological antioxidants have been suggested. The aim of the present study was to investigate the effect of dietary supplementation with the pyridoindole antioxidant stobadine on the myocardial antioxidant status and ultrastructure of streptozotocin-diabetic rats. Diabetic male Wistar rats were fed for 32 weeks a standard diet or a diet supplemented with stobadine (0.05% w/w). Control rats received a standard diet or stobadine-supplemented diet (0.16% w/w). Plasma levels of glucose, cholesterol and triglycerides were increased significantly by diabetes. Activities of superoxide dismutase and catalase were markedly elevated in the diabetic myocardium. Myocardial levels of conjugated dienes increased after eight months of diabetes, in spite of significantly increased myocardial α-tocopherol and coenzyme Q₉ content. The long-term treatment of diabetic animals with stobadine (i) reduced plasma cholesterol and triglyceride levels yet left the severe hyperglycemia unaffected, (ii) reduced oxidative damage of myocardial tissue as measured by conjugated dienes, (iii) reversed myocardial levels of α-tocopherol and coenzyme Q₉ to near control values, (iv) reduced elevated activity of superoxide dismutase in the diabetic myocardium, and (v) attenuated angiopathic and atherogenic processes in the myocardium as assessed by electron microscopy examination. These results are in accordance with the postulated prooxidant role of chronic hyperglycemia and provide further evidence that development of pathological changes in diabetic myocardium is amenable to pharmacological intervention by biological antioxidants. Received: 7 June 2000 / Accepted in revised form: 27 November 2000     

TNFα protects cardiac mitochondria independently of its cell surface receptors

Our novel proposal is that TNFα exerts a direct effect on mitochondrial respiratory function in the heart, independently of its cell surface receptors. TNFα-induced cardioprotection is known to involve reactive oxygen species (ROS) and sphingolipids. We therefore further propose that this direct mitochondrial effect is mediated via ROS and sphingolipids. The protective concentration of TNFα (0.5 ng/ml) was added to isolated heart mitochondria from black 6 × 129 mice (WT) and double TNF receptor knockout mice (TNFR1&2^−/−). Respiratory parameters and inner mitochondrial membrane potential were analyzed in the presence/absence of two antioxidants, N-acetyl-l-cysteine or N-tert-butyl-α-(2-sulfophenyl)nitrone or two antagonists of the sphingolipid pathway, N-oleoylethanolamine (NOE) or imipramine. In WT, TNFα reduced State 3 respiration from 279.3 ± 3 to 119.3 ± 2 (nmol O₂/mg protein/min), increased proton leak from 15.7 ± 0.6% (control) to 36.6 ± 4.4%, and decreased membrane potential by 20.5 ± 3.1% compared to control groups. In TNFR1&2^−/− mice, TNFα reduced State 3 respiration from 205.2 ± 4 to 75.7 ± 1 (p < 0.05 vs. respective control). In WT mice, both antioxidants added with TNFα restored State 3 respiration to 269.2 ± 2 and 257.6 ± 2, respectively. Imipramine and NOE also restored State 3 respiration to 248.4 ± 2 and 249.0 ± 2, respectively (p < 0.01 vs. TNFα alone). Similarly, both antioxidant and inhibitors of the sphingolipid pathway restored the proton leak to pre-TNF values. TNFα-treated mitochondria or isolated cardiac muscle fibers showed an increase in respiration after anoxia–reoxygenation, but this effect was lost in the presence of an antioxidant or NOE. Similar data were obtained in TNFR1&2^−/− mice. TNFα exerts a protective effect on respiratory function in isolated mitochondria subjected to an anoxia–reoxygenation insult. This effect appears to be independent of its cell surface receptors, but is likely to be mediated by ROS and sphingolipids.     

Effect of α-tocopherol and β-carotene supplementation on the incidence of type 2 diabetes

Aims/hypothesis Type 2 diabetes is associated with reduced antioxidant defence. Only a few human studies have investigated the role of antioxidants in the pathogenesis of diabetes. This study aimed to examine whether α-tocopherol or β-carotene affected the occurrence of type 2 diabetes. Methods In the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study, a double-blind, controlled trial, 29,133 male smokers aged 50–69 years were randomised to receive either α-tocopherol (50 mg/day) or β-carotene (20 mg/day) or both agents or placebo daily for 5–8 years (median 6.1 years). Baseline serum samples were analysed for α-tocopherol and β-carotene using HPLC. Cases of diabetes were identified from a nationwide Finnish registry of patients receiving drug reimbursement for diabetes. Of 27,379 men without diabetes at baseline, 705 men were diagnosed with diabetes during the follow-up of up to 12.5 years. Results Baseline serum levels of α-tocopherol and β-carotene were not associated with the risk of diabetes in the placebo group: the relative risk (RR) between the highest and lowest quintiles of α-tocopherol was 1.59 (95% CI 0.89–2.84) and that for β-carotene was 0.66 (95% CI 0.40–1.10). Neither supplementation significantly affected the incidence of diabetes: the RR was 0.92 (95% CI 0.79–1.07) for participants receiving α-tocopherol compared with non-recipients and 0.99 (95% CI 0.85–1.15) for participants receiving β-carotene compared with non-recipients. Conclusions/interpretation Neither α-tocopherol nor β-carotene supplementation prevented type 2 diabetes in male smokers. Serum levels of α-tocopherol and β-carotene were not associated with the risk of type 2 diabetes. ClinicalTrials.gov ID no. NCT00342992     

Effect of aging on treadmill exercise induced theta power in the rat

The effects of aging on the electroencephalogram (EEG) power spectra of 8- and 60-week-old Wistar–Kyoto rats were examined during the waking baseline and treadmill exercise. Using continuous and simultaneous recordings of EEG and electromyogram signals, this study demonstrated that the alpha (10–13 Hz), theta (6–10 Hz), and delta (0.5–4 Hz) powers of the EEG were significantly lower in older rats as compared with young rats during the waking baseline. In the young rats, treadmill exercise resulted promptly in a higher alpha power, higher theta power, and higher theta power percentage as compared with the waking baseline. In the aged rats, treadmill exercise only resulted in a higher theta power and higher theta power percentage. During the treadmill exercise, however, the aged rats still showed a significantly lower exercise-evoked theta power change than the young rats. These results suggested that aging is accompanied by lower EEG activities during waking and this also is accompanied by an attenuated response of the brain to exercise in the rat.