Alterations of antioxidant enzymes and oxidative damage to macromolecules in different organs of rats during aging

Radical Oxygen Species, Exercise and Aging: An Update

It is now well established that reactive oxygen species (ROS) play a dual role as both deleterious and beneficial species. In fact, ROS act as secondary messengers in intracellular signalling cascades; however, they can also induce cellular senescence and apoptosis. Aging is an intricate phenomenon characterized by a progressive decline in physiological functions and an increase in mortality, which is often accompanied by many pathological diseases. ROS are involved in age-associated damage to macromolecules, and this may cause derangement in ROS-mediated cell signalling, resulting in stress and diseases. Moreover, the role of oxidative stress in age-related sarcopenia provides strong evidence for the important contribution of physical activity to limit this process. Regular physical activity is considered a preventive measure against oxidative stress-related diseases. The aim of this review is to summarize the currently available studies investigating the effects of chronic and/or acute physical exercise on the oxidative stress process in healthy elderly subjects. Although studies on oxidative stress and physical activity are limited, the available information shows that acute exercise increases ROS production and oxidative stress damage in older adults, whereas chronic exercise could protect elderly subjects from oxidative stress damage and reinforce their antioxidant defences. The available studies reveal that to promote beneficial effects of physical activity on oxidative stress, elderly subjects require moderate-intensity training rather than high-intensity exercise.

Amelioration of age-dependent increase in oxidative stress markers in male mice by extract of Potentilla fulgens

OBJECTIVE

To investigate the effect of Potentilla fulgens extract on lipid peroxidation and antioxidant status in male mice as a function of age.

METHODS

Eighteen-month-old Swiss albino male mice were administered the dichloromethane-methanol extract of P. fulgens (250 mg/kg b.w.) on alternate days via intraperitoneal route for a period of 14 days. Lipid peroxidation and activities of catalase (CAT) and glutathione peroxidase (GPx1) in liver and kidney were measured and serum oxygen radical absorbance capacity (ORAC) assay was estimated. Phytochemical analysis of P. fulgens extract using high performance thin layer chromatography (HPTLC) was carried out with gallic acid, quercetin, catechin, and epicatechin as markers.

RESULTS

Significant increase in level of thiobarbituric acid-reactive substances (TBARS), decreased GPx1, and CAT activities as well as reduction in ORAC were observed in 18-month-old mice as compared to that of 2-month-old mice. Treatment with P. fulgens extract significantly lowered TBARS level, ameliorated CAT, and GPx1 activities in liver and kidney and improved serum ORAC in aging mice. HPTLC studies revealed well resolved bands of P. fulgens extract containing epicatechin and catechin.

DISCUSSION

This study showed that P. fulgens is a potent antioxidative agent, which can emerge as a promising candidate in alleviating the age-associated oxidative stress and related diseases.

Understanding the physiology of the ageing individual: computational modelling of changes in metabolism and endurance

Ageing and lifespan are strongly affected by metabolism. The maximal possible uptake of oxygen is not only a good predictor of performance in endurance sports, but also of life expectancy. Figuratively speaking, healthy ageing is a competitive sport. Although the root cause of ageing is damage to macromolecules, it is the balance with repair processes that is decisive. Reduced or intermittent nutrition, hormones and intracellular signalling pathways that regulate metabolism have strong effects on ageing. Homeostatic regulatory processes tend to keep the environment of the cells within relatively narrow bounds. On the other hand, the body is constantly adapting to physical activity and food consumption. Spontaneous fluctuations in heart rate and other processes indicate youth and health. A (homeo)dynamic aspect of homeostasis deteriorates with age. We are now in a position to develop computational models of human metabolism and the dynamics of heart rhythm and oxygen transport that will advance our understanding of ageing. Computational modelling of the connections between dietary restriction, metabolism and protein turnover may increase insight into homeostasis of the proteins in our body. In this way, the computational reconstruction of human physiological processes, the Physiome, can help prevent frailty and age-related disease.

Age-dependent changes of the antioxidant system in rat livers are accompanied by altered MAPK activation and a decline in motor signaling

Aging is characterized by a progressive decrease of cellular functions, because cells gradually lose their capacity to respond to injury. Increased oxidative stress is considered to be one of the major contributors to age-related changes in all organs including the liver. Our study has focused on elucidating whether important antioxidative enzymes, the mTOR pathway, and MAPKs exhibit age-dependent changes in the liver of rats during aging. We found an age-dependent increase of GSH in the cytosol and mitochondria. The aged liver showed an increased SOD enzyme activity, while the CAT enzyme activity decreased. HO-1 and NOS-2 gene expression was lower in adult rats, but up-regulated in aged rats. Western blot analysis revealed that SOD1, SOD2, GPx, GR, γ-GCL, and GSS were age-dependent up-regulated, while CAT remained constant. We also demonstrated that the phosphorylation of Akt, JNK, p38, and TSC2(Ser1254) decreased while ERK1/2 and TSC2(Thr1462) increased age-dependently. Furthermore, our data show that the mTOR pathway seems to be activated in livers of aged rats, and hence stimulating cell proliferation/regeneration, as confirmed by an age-dependent increase of PCNA and p-eIF4E(Ser209) protein expression. Our data may help to explain the fact that liver cells only proliferate in cases of necessity, like injury and damage. In summary, we have demonstrated that, age-dependent changes of the antioxidant system and stress-related signaling pathways occur in the livers of rats, which may help to better understand organ aging.

Cellular and molecular biology of aging endothelial cells

Cardiovascular disease (CVD) is the leading cause of death in the United States and aging is a major risk factor for CVD development. One of the major age-related arterial phenotypes thought to be responsible for the development of CVD in older adults is endothelial dysfunction. Endothelial function is modulated by traditional CVD risk factors in young adults, but advancing age is independently associated with the development of vascular endothelial dysfunction. This endothelial dysfunction results from a reduction in nitric oxide bioavailability downstream of endothelial oxidative stress and inflammation that can be further modulated by traditional CVD risk factors in older adults. Greater endothelial oxidative stress with aging is a result of augmented production from the intracellular enzymes NADPH oxidase and uncoupled eNOS, as well as from mitochondrial respiration in the absence of appropriate increases in antioxidant defenses as regulated by relevant transcription factors, such as FOXO. Interestingly, it appears that NFkB, a critical inflammatory transcription factor, is sensitive to this age-related endothelial redox change and its activation induces transcription of pro-inflammatory cytokines that can further suppress endothelial function, thus creating a vicious feed-forward cycle. This review will discuss the two macro-mechanistic processes, oxidative stress and inflammation, that contribute to endothelial dysfunction with advancing age as well as the cellular and molecular events that lead to the vicious cycle of inflammation and oxidative stress in the aged endothelium. Other potential mediators of this pro-inflammatory endothelial phenotype are increases in immune or senescent cells in the vasculature. Of note, genomic instability, telomere dysfunction or DNA damage has been shown to trigger cell senescence via the p53/p21 pathway and result in increased inflammatory signaling in arteries from older adults. This review will discuss the current state of knowledge regarding the emerging concepts of senescence and genomic instability as mechanisms underlying oxidative stress and inflammation in the aged endothelium. Lastly, energy sensitive/stress resistance pathways (SIRT-1, AMPK, mTOR) are altered in endothelial cells and/or arteries with aging and these pathways may modulate endothelial function via key oxidative stress and inflammation-related transcription factors. This review will also discuss what is known about the role of "energy sensing" longevity pathways in modulating endothelial function with advancing age. With the growing population of older adults, elucidating the cellular and molecular mechanisms of endothelial dysfunction with age is critical to establishing appropriate and measured strategies to utilize pharmacological and lifestyle interventions aimed at alleviating CVD risk. This article is part of a Special Issue entitled "SI: CV Aging".

Effect of slaughter age on the antioxidant enzyme activity, color, and oxidative stability of Korean Hanwoo (Bos taurus coreanae) cow beef

This study investigated the effect of slaughter age on the antioxidant enzyme activity, lipid and protein oxidation, and color stability in striploins (M. longissimus lumborum) from Korean Hanwoo (Bos taurus coreanae) cows of different age groups (1.9 to 3.7, 4.0 to 4.8, 5.0 to 5.7, 6.0 to 6.9, and 7.5 to 11.5yr). Myoglobin content and the activities of catalase, superoxide dismutase, and glutathione peroxidase were significantly (P<0.05) increased in older cow beef. During refrigerated storage, 2-thiobarbituric acid reactive substances and protein carbonyls were significantly (P<0.05) increased in the meat from the older cows. The beef from older cows was darker and had lower color stability. These findings suggest that slaughter age has a negative effect on the color and lipid stability of Hanwoo cow beef.

Alternative kynurenic acid synthesis routes studied in the rat cerebellum

Kynurenic acid (KYNA), an astrocyte-derived, endogenous antagonist of α7 nicotinic acetylcholine and excitatory amino acid receptors, regulates glutamatergic, GABAergic, cholinergic and dopaminergic neurotransmission in several regions of the rodent brain. Synthesis of KYNA in the brain and elsewhere is generally attributed to the enzymatic conversion of L-kynurenine (L-KYN) by kynurenine aminotransferases (KATs). However, alternative routes, including KYNA formation from D-kynurenine (D-KYN) by D-amino acid oxidase (DAAO) and the direct transformation of kynurenine to KYNA by reactive oxygen species (ROS), have been demonstrated in the rat brain. Using the rat cerebellum, a region of low KAT activity and high DAAO activity, the present experiments were designed to examine KYNA production from L-KYN or D-KYN by KAT and DAAO, respectively, and to investigate the effect of ROS on KYNA synthesis. In chemical combinatorial systems, both L-KYN and D-KYN interacted directly with peroxynitrite (ONOO(-)) and hydroxyl radicals (OH•), resulting in the formation of KYNA. In tissue homogenates, the non-specific KAT inhibitor aminooxyacetic acid (AOAA; 1 mM) reduced KYNA production from L-KYN and D-KYN by 85.1 ± 1.7% and 27.1 ± 4.5%, respectively. Addition of DAAO inhibitors (benzoic acid, kojic acid or 3-methylpyrazole-5-carboxylic acid; 5 μM each) attenuated KYNA formation from L-KYN and D-KYN by ~35% and ~66%, respectively. ONOO(-) (25 μM) potentiated KYNA production from both L-KYN and D-KYN, and these effects were reduced by DAAO inhibition. AOAA attenuated KYNA production from L-KYN + ONOO(-) but not from D-KYN + ONOO(-). In vivo, extracellular KYNA levels increased rapidly after perfusion of ONOO(-) and, more prominently, after subsequent perfusion with L-KYN or D-KYN (100 μM). Taken together, these results suggest that different mechanisms are involved in KYNA production in the rat cerebellum, and that, specifically, DAAO and ROS can function as alternative routes for KYNA production.

Aqueous Extract of Agaricus blazei Murrill Prevents Age-Related Changes in the Myenteric Plexus of the Jejunum in Rats

This study evaluated the effects of the supplementation with aqueous extract of Agaricus blazei Murrill (ABM) on biometric and blood parameters and quantitative morphology of the myenteric plexus and jejunal wall in aging Wistar rats. The animals were euthanized at 7 (C7), 12 (C12 and CA12), and 23 months of age (C23 and CA23). The CA12 and CA23 groups received a daily dose of ABM extract (26 mg/animal) via gavage, beginning at 7 months of age. A reduction in food intake was observed with aging, with increases in the Lee index, retroperitoneal fat, intestinal length, and levels of total cholesterol and total proteins. Aging led to a reduction of the total wall thickness, mucosa tunic, villus height, crypt depth, and number of goblet cells. In the myenteric plexus, aging quantitatively decreased the population of HuC/D(+) neuronal and S100(+) glial cells, with maintenance of the nNOS(+) nitrergic subpopulation and increase in the cell body area of these populations. Supplementation with the ABM extract preserved the myenteric plexus in old animals, in which no differences were detected in the density and cell body profile of neurons and glial cells in the CA12 and CA23 groups, compared with C7 group. The supplementation with the aqueous extract of ABM efficiently maintained myenteric plexus homeostasis, which positively influenced the physiology and prevented the death of the neurons and glial cells.

D-Galactose Induced Changes in Enzymatic Antioxidant Status in Rats of Different Ages

Considering the preexisting influence of the process of natural aging on antioxidant enzymes activity and the level of lipid peroxidation, the age of the rats at which D-galactose (D-gal) treatment is started could strongly impact the development of D-gal induced senescence. To evaluate this, we subjected 1, 3 and 15 months old rats to D-gal treatment in parallel with having appropriate placebos (0.9 % saline). Our results showed elevated glutathione peroxidase (GPx) activity and no significant changes in superoxide dismutase (SOD), catalase (CAT) and glutathione reductase (GR) activity or malondialdehyde (MDA) levels in relation to natural aging. In mature and aged senescent livers we observed positive correlation between increased ratio R=SOD/(GPx+CAT) and increased MDA concentration. MDA levels seemed to correlate positively with the age of the animals at which D-gal treatment had started. In the case of 3 and 15 months old rats there was D-gal induced decrease in SOD and GR activity, but this effect of the treatment was not observed in 1 month old rats. Our results imply that the changes in the antioxidant enzyme activities are not only under the influence of the D-gal overload, but also depend on the developmental stage of the rats. According to our results, with regard to enzymatic antioxidant capacity and the level of lipid peroxidation, the best age for induction of senescence is somewhere after the third month.

Ozone ameliorates age-related oxidative stress changes in rat liver and kidney: effects of pre- and post-ageing administration

The ageing process is known to be accompanied by increased oxidative stress and compromised antioxidant defenses. Controlled ozone administration has been shown to be effective in various pathophysiological conditions with an underlying oxidative burden. However, its effect on the biochemical alterations associated with the ageing process has been rarely studied. Therefore, the present work was carried out to study the role of ozone in counteracting the state of oxidative stress associated with ageing in rat liver and kidneys using two experimental models. In the pre-ageing model, ozone was administered prior to the onset of ageing at adulthood and continued after the start of the ageing process (3-month-old rats until the age of 15 months). While in the post-ageing model, ozone was administered after ageing has begun and lasted for one month (14-month-old rats until the age of 15 months). The pre-ageing ozone administration effectively reduced lipid and protein oxidation markers, namely, malondialdehyde and protein carbonyl levels and decreased lipofuscin pigment deposition in rat liver and kidneys. Moreover, it significantly restored hepatic and renal reduced glutathione (GSH) contents and normalized cytosolic hepatic glutathione peroxidase activity. Similar but less pronounced effects were observed in the post-ageing ozone-treated group. Nevertheless, in the latter model ozone administration failed to significantly affect liver and kidney lipofuscin levels, as well as kidney GSH contents. These data provide evidences for potentially positive effects of pre-ageing ozone therapy in neutralizing chronic oxidative stress associated with ageing in rat liver and kidneys.

Liver function parameters in hip fracture patients: relations to age, adipokines, comorbidities and outcomes

AIM

To asses liver markers in older patients with hip fracture (HF) in relation to age, comorbidities, metabolic characteristics and short-term outcomes.

METHODS

In 294 patients with HF (mean age 82.0±7.9 years, 72.1% women) serum alanine aminotransferase (ALT), gammaglutamyltransferase (GGT), alkaline phosphatase (ALP), albumin, bilirubin, 25(OH)vitaminD, PTH, calcium, phosphate, magnesium, adiponectin, leptin, resistin, thyroid function and cardiac troponin I were measured.

RESULTS

Elevated ALT, GGT, ALP or bilirubin levels on admission were observed in 1.7%-9.9% of patients. With age GGT, ALT and leptin decrease, while PTH and adiponectin concentrations increase. Higher GGT (>30 U/L, median level) was associated with coronary artery disease (CAD), diabetes mellitus (DM), and alcohol overuse; lower ALT (≤20 U/L, median level) with dementia; total bilirubin>20 μmol/L with CAD and alcohol overuse; and albumin>33 g/L with CAD. Multivariate adjusted regression analyses revealed ALT, ALP, adiponectin, alcohol overuse and DM as independent and significant determinants of GGT (as continuous or categorical variable); GGT for each other liver marker; and PTH for adiponectin. The risk of prolonged hospital stay (>20 days) was about two times higher in patients with GGT>30 U/L or adiponectin>17.14 ng/L (median level) and 4.7 times higher if both conditions coexisted. The risk of in-hospital death was 3 times higher if albumin was <33 g/L.

CONCLUSIONS

In older HF patients liver markers even within the normal range are associated with age-related disorders and outcomes. Adiponectin (but not 25(OH)vitaminD, PTH, leptin or resistin) is an independent contributor to higher GGT. Serum GGT and albumin predict prolonged hospital stay and in-hospital death, respectively. A unifying hypothesis of the findings presented.

The effects of Ginkgo biloba extract on cognitive functions in aged female rats: the role of oxidative stress and brain-derived neurotrophic factor

The aim of this study was to investigate the effects of Ginkgo biloba extract (GBE) on cognitive functions as well as oxidative stress and brain-derived neurotrophic factor (BDNF) levels in aged female rats. Rats were divided into 4 groups according to age (young vs. aged) and treatment (GBE vs. vehicle). GBE or vehicle was given for 30 d, and a series of behavioral tests were performed. Following behavioral testing, blood samples and brain tissues were obtained for analysis of BDNF, malondialdehyde (MDA), 8-hydroxy-2'-deoxyguanosine (8-OHdG), and glutathione levels, and superoxide dismutase activity. Locomotor activity and anxiety levels were lower in the aged rats. Based on Morris water maze probe trial findings, GBE supplementation increased the number of platform crossings in the aged rats. MDA and 8-OHdG levels were lower in the brain tissue, and BDNF levels were higher in plasma in the rates treated with GBE. Based on these findings, we concluded that GBE supplementation improved cognitive functions by decreasing oxidative damage and increasing the BDNF level in aged female rats.

Preventive effect of safranal against oxidative damage in aged male rat brain

An imbalance between production of reactive oxygen species (ROS) and its elimination by antioxidant defense system in the body has been implicated for causes of aging and neurodegenerative diseases. This study was design to assess the changes in activities of antioxidant enzymes (superoxide dismutase (SOD), glutathione-S-transferase (GST), catalase), lipid peroxidation and reduced glutathione (GSH) levels in the brain of 2, 10 and 20 month old rats, and to determine the effect of safranal on the status of selected oxidative stress indices in the 10 and 20 month old rats. The aged rats (10 and 20 months) were given intraperitoneal injections of safranal (0.5 mg/kg day) daily for one month. The results of this study demonstrated that aging caused significant increase in the level of lipid peroxidation as well decrease in the GSH level and activities of SOD and GST in the brain of aging rats. The results of this study showed that safranal ameliorated the increased lipid peroxidation level as well as decreased GSH content of the brain of 10 and 20 month old rats. In addition, safranal treatment to the 20 month old rats, which restored the SOD and GST activities. In conclusion, safranal can be effective to protect susceptible aged brain from oxidative damage by increasing antioxidant defenses.

Calcium signaling alterations, oxidative stress, and autophagy in aging

SIGNIFICANCE

Aging is a multi-factorial process that may be associated with several functional and structural deficits which can evolve into degenerative diseases. In this review, we present data that may depict an expanded view of molecular aging theories, beginning with the idea that reactive oxygen species (ROS) are the major effectors in this process. In addition, we have correlated the importance of autophagy as a neuroprotective mechanism and discussed a link between age-related molecules, Ca(2+) signaling, and oxidative stress.

RECENT ADVANCES

There is evidence suggesting that alterations in Ca(2+) homeostasis, including mitochondrial Ca(2+) overload and alterations in electron transport chain (ETC) complexes, which increase cell vulnerability, are linked to oxidative stress in aging. As much as Ca(2+) signaling is altered in aged cells, excess ROS can be produced due to an ineffective coupling of mitochondrial respiration. Damaged mitochondria might not be removed by the macroautophagic system, which is hampered in aging by lipofuscin accumulation, boosting ROS generation, damaging DNA, and, ultimately, leading to apoptosis.

CRITICAL ISSUES

This process can lead to altered protein expression (such as p53, Sirt1, and IGF-1) and progress to cell death. This cycle can lead to increased cell vulnerability in aging and contribute to an increased susceptibility to degenerative processes.

FUTURE DIRECTIONS

A better understanding of Ca(2+) signaling and molecular aging alterations is important for preventing apoptosis in age-related diseases. In addition, caloric restriction, resveratrol and autophagy modulation appear to be predominantly cytoprotective, and further studies of this process are promising in age-related disease therapeutics.

Age-related learning and memory deficits in rats: role of altered brain neurotransmitters, acetylcholinesterase activity and changes in antioxidant defense system

Oxidative stress from generation of increased reactive oxygen species or free radicals of oxygen has been reported to play an important role in the aging. To investigate the relationship between the oxidative stress and memory decline during aging, we have determined the level of lipid peroxidation, activities of antioxidant enzymes, and activity of acetylcholine esterase (AChE) in brain and plasma as well as biogenic amine levels in brain from Albino-Wistar rats at age of 4 and 24 months. The results showed that the level of lipid peroxidation in the brain and plasma was significantly higher in older than that in the young rats. The activities of antioxidant enzymes displayed an age-dependent decline in both brain and plasma. Glutathione peroxidase and catalase activities were found to be significantly decreased in brain and plasma of aged rats. Superoxide dismutase (SOD) was also significantly decreased in plasma of aged rats; however, a decreased tendency (non-significant) of SOD in brain was also observed. AChE activity in brain and plasma was significantly decreased in aged rats. Learning and memory of rats in the present study was assessed by Morris Water Maze (MWM) and Elevated plus Maze (EPM) test. Short-term memory and long-term memory was impaired significantly in older rats, which was evident by a significant increase in the latency time in MWM and increase in transfer latency in EPM. Moreover, a marked decrease in biogenic amines (NA, DA, and 5-HT) was also found in the brain of aged rats. In conclusion, our data suggest that increased oxidative stress, decline of antioxidant enzyme activities, altered AChE activity, and decreased biogenic amines level in the brain of aged rats may potentially be involved in diminished memory function.

The effect of sildenafil and udenafil on testicular damage following ischemia-reperfusion injury in rats

PURPOSE

Ischemia-reperfusion injury can cause testicular damage and phosphodiesterase inhibitors are reported to regulate antioxidant activity. We investigated the prevention of ipsilateral and contralateral testicular damage using 2 phosphodiesterase inhibitors after testicular detorsion in rats.

MATERIALS AND METHODS

A total of 28 adult male rats were randomly divided into 4 groups of 7 each, including group 1-sham operation, group 2-testicular torsion and detorsion, group 3- testicular torsion and detorsion with sildenafil administration before detorsion and group 4- testicular torsion and detorsion with udenafil administration before detorsion. Tissue levels of malondialdehyde, total sulfhydryl and nitrite were evaluated, and histopathological changes in the groups were examined.

RESULTS

Compared to group 1 significantly increased tissue malondialdehyde (p = 0.001), significantly decreased total sulfhydryl (p = 0.038) and insignificantly increased nitrite were found in group 2. Compared to group 2 malondialdehyde decreased significantly and total sulfhydryl increased significantly in groups 3 and 4. The decrease in nitrite was insignificant in the latter 2 groups. Histopathology revealed increased hemorrhage, congestion and edema in group 2 rats. The testicular injury score was lower in groups 3 and 4. In group 2 grades II to IV injury was detected while most specimens in treated groups showed grade II injury.

CONCLUSIONS

This study indicates that intraperitoneal administration of sildenafil and udenafil efficiently suppresses radical production while decreasing histological changes after testicular ischemia-reperfusion injury.

Nicotinamide preferentially protects glycolysis in dermal fibroblasts under oxidative stress conditions

BACKGROUND

Daily exposure of human skin to environmental insults such as solar radiation, pollution and smoke can lead to an elevation of oxidative stress, causing premature acceleration of skin ageing. Oxidative stress is known to disrupt cellular metabolism, which negatively impacts the skin's functionality at the cellular and tissue level.

OBJECTIVES

To examine the changes in cellular metabolism due to oxidative stress.

METHODS

Glycolysis and oxidative phosphorylation rates in human dermal fibroblasts were monitored in real time under controlled nonlethal oxidative stress conditions. Hydrogen peroxide was utilized as a surrogate stressor because numerous environmental stressors as well as intrinsic ageing trigger its production.

RESULTS

Hydrogen peroxide ranging between 0.5 and 3 mmol L(-1) caused a significant decrease in glycolytic and oxidative phosphorylation rates along with cellular ATP levels. Nicotinamide (NAM) was found to protect dose dependently as well as restore glycolytic rates concurrent with restoring ATP to control levels. NAM had an effective dose-response range between 0.1 and 1.0 mmol L(-1) , with maximal effects attained at 0.5 mmol L(-1) . Relative to oxidative phosphorylation, NAM was able to provide a diminished level of protection. FK866, a known NAM phosphoribosyltransferase inhibitor, was found to inhibit the protective effects of NAM significantly, suggesting part of the NAM mechanism of action involves nicotinamide adenine dinucleotide (NAD(+) ) synthesis.

CONCLUSIONS

These results support previous findings that NAM protects cellular metabolism from oxidative stress by preferentially affecting glycolysis. Additionally, part of its mechanism of action appears to include NAD(+) synthesis.

Do we age because we have mitochondria?

The process of aging remains a great riddle. Production of reactive oxygen species (ROS) by mitochondria is an inevitable by-product of respiration, which has led to a hypothesis proposing the oxidative impairment of mitochondrial components (e.g., mtDNA, proteins, lipids) that initiates a vicious cycle of dysfunctional respiratory complexes producing more ROS, which again impairs function. This does not exclude other processes acting in parallel or targets for ROS action in other organelles than mitochondria. Given that aging is defined as the process leading to death, the role of mitochondria-based impairments in those organ systems responsible for human death (e.g., the cardiovascular system, cerebral dysfunction, and cancer) is described within the context of "garbage" accumulation and increasing insulin resistance, type 2 diabetes, and glycation of proteins. Mitochondrial mass, fusion, and fission are important factors in coping with impaired function. Both biogenesis of mitochondria and their degradation are important regulatory mechanisms stimulated by physical exercise and contribute to healthy aging. The hypothesis of mitochondria-related aging should be revised to account for the limitations of the degradative capacity of the lysosomal system. The processes involved in mitochondria-based impairments are very similar across a large range of organisms. Therefore, studies on model organisms from yeast, fungi, nematodes, flies to vertebrates, and from cells to organisms also add considerably to the understanding of human aging.

Dried apple enriched with mandarin juice counteracts tamoxifen-induced oxidative stress in rats

The effect of a product made of dehydrated apples enriched with mandarin juice by vacuum impregnation on markers of oxidative stress (plasma antioxidant capacity, carbonyl groups (CGs), 8-hydroxydeoxyguanosine (8OHdG) and α-tocopherol) was tested in rats. Six groups of animals were studied: one group was fed a standard diet; two groups were supplemented with dehydrated apple either impregnated or not with mandarin juice throughout 28 days; and three groups (one unsupplemented and two supplemented) were additionally treated with tamoxifen (TAM) for 21 days used for induction of oxidative stress. The rats treated with TAM showed an increase in aminotransferases, CGs and 8OHdG. All of these effects were significantly decreased in the animals after apple snack consumption; the addition of mandarin juice into the apple mainly accounts for increased levels of α-tocopherol in plasma and liver. These findings suggest that the food product have a protective action against oxidative stress induced by TAM in rats.

Toxic effect of cooking oil fumes in primary fetal pulmonary type II-like epithelial cells

Epidemiological studies indicated that there is an increased risk of respiratory tract cancer among cooks and bakers. The cooking oil fumes are believed to conduct this risk, and many studies have focused on evaluating the mutagenicity and finding the mutagenic components in oil fumes. COFs contains two major classes of compounds. One class consists of polycyclic aromatic hydrocarbons (PAHs), such as benzo[a]pyrene, benzo[b]fluoranthene, fluoranthene, and benzo[g,h,i]perylene. BaP is a known immunosuppressant. It can also alter cell cycle progression, induce inflammation, and impair DNA repair and apoptotic processes leading to aberrant cellular functioning. This study investigates the effect of toxicity of cooking oil fumes (COFs) in primary ICR mice' fetal lung type II-like epithelium cells (AEC II). The cells were cultured in different concentrations (0, 12.5, 25, 50, 100, and 200μg/ml) of COFs for different time periods. The results showed that cell viability decreased in a dose- and time- dependent manner, which is accompanied by increased malondialdehyde (MDA) level and decreased superoxide dismutase (SOD) and glutathione (GSH) activities. Moreover, comet assay suggested DNA damage, as well as increased production of DNA adducts induced by PAHs. The present study also shows that COFs may disturb cell cycles even at a very low dose. In summary, the present study indicates that COFs may lead to toxicity in AEC II cells.

Age-dependent exacerbation of white matter stroke outcomes: a role for oxidative damage and inflammatory mediators

BACKGROUND AND PURPOSE

Subcortical white matter stroke (WMS) constitutes up to 30% of all stroke subtypes. Mechanisms of oligodendrocyte and axon injury and repair play a central role in the damage and recovery after this type of stroke, and a comprehensive study of these processes requires a specialized experimental model that is different from common large artery, gray matter stroke models. Diminished recovery from stroke in aged patients implies that damage and repair processes are affected by advanced age, but such effects have not been studied in WMS.

METHODS

WMS was produced with focal microinjection of the vasoconstrictor N5-(1-iminoethyl)-L-ornithine into the subcortical white matter ventral to the mouse forelimb motor cortex in young adult (2 months), middle-aged (15 months), and aged mice (24 months).

RESULTS

WMS produced localized oligodendrocyte cell death with higher numbers of apoptotic cells and greater oxidative damage in aged brains than in young-adult brains. Increased expression of monocyte chemotactic protein-1 and tumor necrosis factor-α in motor cortex neurons correlated with a more distributed microglial activation in aged brains 7 days after WMS. At 2 months, aged mice displayed increased white matter atrophy and greater loss of corticostriatal connections compared with young-adult mice. Behavioral testing revealed an age-dependent exacerbation of forelimb motor deficits caused by the stroke, with decreased long-term functional recovery in aged animals.

CONCLUSIONS

Age has a profound effect on the outcome of WMS, with more prolonged cell death and oxidative damage, increased inflammation, greater secondary white matter atrophy, and a worse behavioral effect in aged versus young-adult mice.

Protective effect of tannic acid on the brain of adult rats exposed to cadmium and lead

Chronic exposure to Cd and Pb causes brain damage. Tannic acid (TA) is a very efficient chelator for metals. The effect of exposure to Cd and/or Pb and TA on the rats' brain were studied. Two experiments were carried. In experiment no. 1 metals were administered with feed (7mg Cd and 50mgPb/kg) and TA with drink (0, 0.5, 1, 1.5, 2 or 2.5% solutions). In experiment no. 2, rats received an aqueous solutions of [Cd (7 or 14mg/L) or Pb (50 or 100mg/L)] or 2% TA, alternatively every 7 days. In both experiments, TA had a positive effect only on reducing the accumulation of Cd. Exposure to metals resulted in an decrease of superoxide dismutase and catalase activity, whereas TA administration increased those. The results suggests that TA are more effective if taken parallel to food contaminated by Cd, and their effectiveness is higher if their intake is long-term.

Evidence of oxidative injury during aging of the liver in a mouse model

The aim of the present study was to determine whether oxidative stress contributes to aging of the liver in a mouse model. Liver was obtained from young (3-5 months old) and aged (18-24 months old) mice. No age-induced gross changes in liver morphology were detected by light microscopy. Apoptosis was measured using the fragment end labeling of DNA for the immunohistochemical identification of the apoptotic nuclei. The total apoptotic cells represented 1% of the total cells in livers of young mice and 8% in those of aged mice. Among the total apoptotic cells in livers of aged animals, 15% were hepatocytes, 40% sinusoidal endothelial cells, and 45% bile duct cells. Hepatic lipid peroxidation, expressed as malonaldehyde levels, protein oxidation, measured by protein carbonyl content, and DNA oxidation, measured as 8-hydroxy-2'-deoxyguanosine (oxo(8)dG), were significantly increased in the livers of aged animals as compared to younger mice. The apoptotic cells presented elevated levels of oxidized DNA, detected by immunohistochemistry using an antibody directed against oxo(8)dG in serial sections. These results suggest that livers of aged animals presents evidence of increased oxidative injury and apoptosis. Because the apoptotic cells in the aged livers are mostly bile duct cells and sinusoidal endothelial cells, the cells most sensitive to oxidative stress injury, it can be hypothesized that reactive oxygen species-induced apoptosis in these cells contributes to the aging of the liver.

Evidence suggesting a nitric oxide-scavenging activity for traditional crude drugs, and action mechanisms of Sanguisorbae Radix against oxidative stress and aging

In this series of experiments, we found that Sanguisorbae Radix extract possesses strong free radical-scavenging activity in vitro and in vivo. This crude drug protected against renal disease, which is closely associated with excessive generation of reactive oxygen species. We also showed that Sanguisorbae Radix extract can suppress lipid peroxidation and stimulate an antioxidant defense ability in SAM, suggesting that this crude drug may be an effective agent for ameliorating the pathological conditions related to excessive generation of free radicals and oxidant damage, particularly in the aging process.

Neuroactive effects of cotinine on the hippocampus: behavioral and biochemical parameters

The present work evaluated the effects of nicotine (NIC), cotinine (COT), mecamylamine (MEC), methyllycaconitine (MLA) and dihydro-beta-eritroidine (DHβE) on memory extinction and the following biochemical parameters of the hippocampus: lipid peroxidation (LPO), antioxidant capacity (AC) and the phosphorylation of Extracellular-Signal-Regulated Kinase (ERK 1/2). Young male rats that were implanted bilaterally with cannulae were submitted to memory extinction tests sessions, and their hippocampi were dissected for biochemical assays. The extinction of fear memory was significantly improved by both nicotine and its metabolite. Cotinine significantly increased LPO, while nicotine significantly decreased it. Antioxidant capacity was increased by all treatments. Our results showed that cotinine, unlike nicotine, may increase oxidative stress in the hippocampus, but this increase depends upon the dose used and happens without causing corresponding impairments in cognitive function. Cotinine also increased the phosphorylation of ERK 1/2 in a similar fashion as nicotine. Considering these results, it is plausible to wonder to what extent nicotine-attributed effects are really due to the actions of this alkaloid and whether they could be due instead to cotinine or to cotinine-nicotine interactions within the brain.

Dietary iron concentration may influence aging process by altering oxidative stress in tissues of adult rats

Iron is an essential element. However, in its free form, iron participates in redox-reactions, leading to the production of free radicals that increase oxidative stress and the risk of damaging processes. Living organisms have an efficient mechanism that regulates iron absorption according to their iron content to protect against oxidative damage. The effects of restricted and enriched-iron diets on oxidative stress and aging biomarkers were investigated. Adult Wistar rats were fed diets containing 10, 35 or 350 mg/kg iron (adult restricted-iron, adult control-iron and adult enriched-iron groups, respectively) for 78 days. Rats aged two months were included as a young control group. Young control group showed higher hemoglobin and hematocrit values, lower levels of iron and lower levels of MDA or carbonyl in the major studied tissues than the adult control group. Restricted-iron diet reduced iron concentrations in skeletal muscle and oxidative damage in the majority of tissues and also increased weight loss. Enriched-iron diet increased hematocrit values, serum iron, gamma-glutamyl transferase, iron concentrations and oxidative stress in the majority of tissues. As expected, young rats showed higher mRNA levels of heart and hepatic L-Ferritin (Ftl) and kidneys SMP30 as well as lower mRNA levels of hepatic Hamp and interleukin-1 beta (Il1b) and also lower levels of liver protein ferritin. Restricted-iron adult rats showed an increase in heart Ftl mRNA and the enriched-iron adult rats showed an increase in liver nuclear factor erythroid derived 2 like 2 (Nfe2l2) and Il1b mRNAs and in gut divalent metal transporter-1 mRNA (Slc11a2) relative to the control adult group. These results suggest that iron supplementation in adult rats may accelerate aging process by increasing oxidative stress while iron restriction may retards it. However, iron restriction may also impair other physiological processes that are not associated with aging.

Oxygen consumption and usage during physical exercise: the balance between oxidative stress and ROS-dependent adaptive signaling

The complexity of human DNA has been affected by aerobic metabolism, including endurance exercise and oxygen toxicity. Aerobic endurance exercise could play an important role in the evolution of Homo sapiens, and oxygen was not important just for survival, but it was crucial to redox-mediated adaptation. The metabolic challenge during physical exercise results in an elevated generation of reactive oxygen species (ROS) that are important modulators of muscle contraction, antioxidant protection, and oxidative damage repair, which at moderate levels generate physiological responses. Several factors of mitochondrial biogenesis, such as peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α), mitogen-activated protein kinase, and SIRT1, are modulated by exercise-associated changes in the redox milieu. PGC-1α activation could result in decreased oxidative challenge, either by upregulation of antioxidant enzymes and/or by an increased number of mitochondria that allows lower levels of respiratory activity for the same degree of ATP generation. Endogenous thiol antioxidants glutathione and thioredoxin are modulated with high oxygen consumption and ROS generation during physical exercise, controlling cellular function through redox-sensitive signaling and protein-protein interactions. Endurance exercise-related angiogenesis, up to a significant degree, is regulated by ROS-mediated activation of hypoxia-inducible factor 1α. Moreover, the exercise-associated ROS production could be important to DNA methylation and post-translation modifications of histone residues, which create heritable adaptive conditions based on epigenetic features of chromosomes. Accumulating data indicate that exercise with moderate intensity has systemic and complex health-promoting effects, which undoubtedly involve regulation of redox homeostasis and signaling.

Age-dependent guanine oxidation in DNA of different brain regions of Wistar rats and prematurely aging OXYS rats

BACKGROUND

Oxidative damage to the cell, including the formation of 8-oxoG, has been regarded as a significant factor in carcinogenesis and aging. An inbred prematurely aging rat strain (OXYS) is characterized by high sensitivity to oxidative stress, lipid peroxidation, protein oxidation, DNA rearrangements, and pathological conditions paralleling several human degenerative diseases including learning and memory deterioration.

METHODS

We have used monoclonal antibodies against a common pre-mutagenic base lesion 8-oxoguanine (8-oxoG) and 8-oxoguanine DNA glycosylase (OGG1) in combination with indirect immunofluorescence microscopy and image analysis to follow the relative amounts and distribution of 8-oxoG and OGG1 in various cells of different brain regions from OXYS and control Wistar rats.

RESULTS

It was shown that 8-oxoG increased with age in mature neurons, nestin- and glial fibrillary acidic protein (GFAP)-positive cells of hippocampus and frontal cortex in both strains of rats, with OXYS rats always displaying statistically significantly higher levels of oxidative DNA damage than Wistar rats. The relative content of 8-oxoG and OGG1 in nestin- and GFAP-positive cells was higher than in mature neurons in both Wistar and OXYS rats. However, there was no significant interstrain difference in the content of OGG1 for all types of cells and brain regions analyzed, and no difference in the relative content of 8-oxoG between different brain regions.

CONCLUSIONS

Oxidation of guanine may play an important role in the development of age-associated decrease in memory and learning capability of OXYS rats.

GENERAL SIGNIFICANCE

The findings are important for validation of the OXYS rat strain as a model of mammalian aging.

Antioxidant enzyme activity and malondialdehyde levels can be modulated by Piper betle, tocotrienol rich fraction and Chlorella vulgaris in aging C57BL/6 mice

OBJECTIVE

The aim of this study was to determine the erythrocyte antioxidant enzyme activity and the superoxide dismutase, catalase, glutathione peroxidase, and plasma malondialdehyde levels in aging mice and to evaluate how these measures are modulated by potential antioxidants, including the tocotrienol-rich fraction, Piper betle, and Chlorella vulgaris.

METHOD

One hundred and twenty male C57BL/6 inbred mice were divided into three age groups: young (6 months old), middle-aged (12 months old), and old (18 months old). Each age group consisted of two control groups (distilled water and olive oil) and three treatment groups: Piper betle (50 mg/kg body weight), tocotrienol-rich fraction (30 mg/kg), and Chlorella vulgaris (50 mg/kg). The duration of treatment for all three age groups was two months. Blood was withdrawn from the orbital sinus to determine the antioxidant enzyme activity and the malondialdehyde level.

RESULTS

Piper betle increased the activities of catalase, glutathione peroxidase, and superoxide dismutase in the young, middle, and old age groups, respectively, when compared to control. The tocotrienol-rich fraction decreased the superoxide dismutase activity in the middle and the old age groups but had no effect on catalase or glutathione peroxidase activity for all age groups. Chlorella vulgaris had no effect on superoxide dismutase activity for all age groups but increased glutathione peroxidase and decreased catalase activity in the middle and the young age groups, respectively. Chlorella vulgaris reduced lipid peroxidation (malondialdehyde levels) in all age groups, but no significant changes were observed with the tocotrienol-rich fraction and the Piper betle treatments.

CONCLUSION

We found equivocal age-related changes in erythrocyte antioxidant enzyme activity when mice were treated with Piper betle, the tocotrienol-rich fraction, and Chlorella vulgaris. However, Piper betle treatment showed increased antioxidant enzymes activity during aging.

Protein damage, repair and proteolysis

Proteins are continuously affected by various intrinsic and extrinsic factors. Damaged proteins influence several intracellular pathways and result in different disorders and diseases. Aggregation of damaged proteins depends on the balance between their generation and their reversal or elimination by protein repair systems and degradation, respectively. With regard to protein repair, only few repair mechanisms have been evidenced including the reduction of methionine sulfoxide residues by the methionine sulfoxide reductases, the conversion of isoaspartyl residues to L-aspartate by L-isoaspartate methyl transferase and deglycation by phosphorylation of protein-bound fructosamine by fructosamine-3-kinase. Protein degradation is orchestrated by two major proteolytic systems, namely the lysosome and the proteasome. Alteration of the function for both systems has been involved in all aspects of cellular metabolic networks linked to either normal or pathological processes. Given the importance of protein repair and degradation, great effort has recently been made regarding the modulation of these systems in various physiological conditions such as aging, as well as in diseases. Genetic modulation has produced promising results in the area of protein repair enzymes but there are not yet any identified potent inhibitors, and, to our knowledge, only one activating compound has been reported so far. In contrast, different drugs as well as natural compounds that interfere with proteolysis have been identified and/or developed resulting in homeostatic maintenance and/or the delay of disease progression.

The potential role of ozone in ameliorating the age-related biochemical changes in male rat cerebral cortex

Controlled ozone (O(3)) administration is known to promote oxidative preconditioning and, thus, may reverse chronic oxidative stress that accompanies aging. Therefore, the present work was undertaken to study the potential role of O(3) in ameliorating certain age-related biochemical changes represented by impaired activities of inner mitochondrial membrane enzymes, compromised energy production and increased oxidative burden in male rat cerebral cortex. Prophylactic administration of O(3)-O(2) mixture to 3 month-old rats, at an intrarectal dose of 0.6 mg O(3) kg(-1) body weight twice/week for 3 months then once/week until the age of 15 months, normalized reduced glutathione content, adenosine triphosphate/adenosine diphosphate ratio, mitochondrial superoxide dismutase (SOD) and complex IV (cytochrome-c oxidase) activities, improved glutathione redox index (GSHRI), complex I (NADH-ubiquinone oxidoreductase) and mitochondrial nitric oxide synthase (mtNOS) activities, and attenuated the rise in malondialdehyde (MDA) and mitochondrial protein carbonyl levels. On the other hand, therapeutic administration of the same dose of O(3)-O(2) mixture to 14 month-old rats three times/week for 1 month, reduced mitochondrial protein carbonyl level only. Other favorable effects, including normalization of Na,K-adenosine triphosphatase (Na,K-ATPase) activity and reduction in lipofuscin level in the prophylactic group, as well as improvement in mitochondrial SOD and complex I activities with a decrease in total MDA level in the therapeutic group, were comparable to the effects observed in the corresponding O(2)-treated control groups. In conclusion, the present study revealed that prophylactic administration of O(3)-O(2) mixture provided better amelioration of age-related cerebrocortical alterations by combining the advantages of both O(3) and O(2) therapies.

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 (3 months) and aged rats (24 months). 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.

Cerebral white matter oxidation and nitrosylation in young rodents with kaolin-induced hydrocephalus

Hydrocephalus is associated with reduced blood flow in periventricular white matter. To investigate hypoxic and oxidative damage in the brains of rats with hydrocephalus, kaolin was injected into the cisterna magna of newborn 7- and 21-day-old Sprague-Dawley rats, and ventricle size was assessed by magnetic resonance imaging at 7, 21, and 42 days of age. In-situ evidence of hypoxia in periventricular capillaries and glial cells was shown by pimonidazole hydrochloride binding. Biochemical assay of thiobarbituric acid reaction and immunohistochemical detection of malondialdehyde and 4-hydroxy-2-nonenal indicated the presence of lipid peroxidation in white matter. Biochemical assay of nitrite indicated increased nitric oxide production. Nitrotyrosine immunohistochemistry showed nitrosylated proteins in white matter reactive microglia and astrocytes. Activities of the antioxidant enzymes catalase and glutathione peroxidase were not increased, and altered hypoxia-inducible factor 1α was not detected by quantitative reverse transcription-polymerase chain reaction. Cerebral vascular endothelial growth factor expression determined by quantitative reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay was not changed, but vascular endothelial growth factor immunoreactivity was increased in reactive astrocytes of hydrocephalic white matter. To determine if nitric oxide synthase is involved in the pathogenesis, we induced hydrocephalus in 7-day-old wild-type and neuronal nitric oxide synthase-deficient mice. At 7 days, the wild-type and mutant mice exhibited equally severe ventriculomegaly and no behavioral differences, although increased glial fibrillary acidic protein was less in the mutant mice. We conclude that hypoxia, via peroxidation and nitrosylation, contributes to brain changes in young rodents with hydrocephalus and that compensatory mechanisms are negligible.

Functional foods and nutraceuticals in the primary prevention of cardiovascular diseases

Cardiovascular disease (CVD) is now the leading cause of death globally and is a growing health concern. Dietary factors are important in the pathogenesis of CVD and may to a large degree determine CVD risk, but have been less extensively investigated. Functional foods are those that are thought to have physiological benefits and/or reduce the risk of chronic disease beyond their basic nutritional functions. The food industry has started to market products labelled as “functional foods.” Although many review articles have focused on individual dietary variables as determinants of CVD that can be modified to reduce the risk of CVD, the aim of this current paper was to examine the impact of functional foods in relation to the development and progression of CVD. Epidemiologic studies have demonstrated the association between certain dietary patterns and cardiovascular health. Research into the cardio-protective potential of their dietary components might support the development of functional foods and nutraceuticals. This paper will also compare the effect of individual bioactive dietary compounds with the effect of some dietary patterns in terms of their cardiovascular protection.

Attenuation of age-related changes in FOXO3a activity and the PI3K/Akt pathway by short-term feeding of ferulate

Ferulate (4-hydroxy-3-methoxycinnamic acid) is a well-known phenolic compound that scavenges free radicals and exerts anti-inflammatory effects. Forkhead box O3a (FOXO3a), a transcription factor that plays important roles in aging processes, decreases with age and is negatively regulated through phosphorylation by phosphatidylinositol 3-kinase (PI3K)/Akt signaling. The present study investigated the efficacy of short-term ferulate feeding on age-related changes in PI3K/Akt/FOXO3a and upstream insulin signaling pathways in aged rats. In addition, changes in manganese superoxide dismutase (MnSOD) and catalase expression were examined because of their dependence on PI3K/Akt/FOXO3a activity. Short-term feeding experiments were done with a diet containing ferulate that was given to aged rats at doses of 3 or 6 mg kg(-1) day(-1) for 10 days. Results showed that FOXO3a activity was increased in the ferulate-fed old group compared with the control old group. Also, ferulate suppressed the PI3K/Akt signaling pathway that is responsible for FOXO3a inhibition in aged rats. Plasma insulin levels and the upstream insulin signaling pathway were also modulated by ferulate correspondingly with PI3K/Akt/FOXO3a activity. The age-related decrease in two major antioxidant enzymes, MnSOD and catalase, was blunted by ferulate, which was accompanied by FOXO3a transcriptional activity. The significance of the present study is the finding that short-term feeding of ferulate effectively modulates age-related renal FOXO3a, PI3K/Akt and insulin signaling pathways, and MnSOD and catalase expression, all of which may be beneficial for attenuating the aging process.

Flow injection catalase activity measurement based on gold nanoparticles/carbon nanotubes modified glassy carbon electrode

Amperometric flow injection method of hydrogen peroxide analysis was developed based on catalase enzyme (CAT) immobilization on a glassy carbon electrode (GC) modified with electrochemically deposited gold nanoparticles on a multiwalled carbon nanotubes/chitosan film. The resulting biosensor was applied to detect hydrogen peroxide with a linear response range 1.0×10(-7)-2.5×10(-3)M with a correlation coefficient 0.998 and response time less than 10s. The optimum conditions of film deposition such as potential applied, deposition time and pH were tested and the flow injection conditions were optimized to be: flow rate of 3ml/min, sample volume 75μl and saline phosphate buffer of pH 6.89. Catalase enzyme activity was successfully determined in liver homogenate samples of rats, raised under controlled dietary plan, using a flow injection analysis system involving the developed biosensor simultaneously with spectrophotometric detection, which is the common method of enzymatic assay.