Relationship between antioxidant defenses and longevity in different mammalian species

Metabolite itaconate in host immunoregulation and defense

Metabolic states greatly influence functioning and differentiation of immune cells. Regulating the metabolism of immune cells can effectively modulate the host immune response. Itaconate, an intermediate metabolite derived from the tricarboxylic acid (TCA) cycle of immune cells, is produced through the decarboxylation of cis-aconitate by cis-aconitate decarboxylase in the mitochondria. The gene encoding cis-aconitate decarboxylase is known as immune response gene 1 (IRG1). In response to external proinflammatory stimulation, macrophages exhibit high IRG1 expression. IRG1/itaconate inhibits succinate dehydrogenase activity, thus influencing the metabolic status of macrophages. Therefore, itaconate serves as a link between macrophage metabolism, oxidative stress, and immune response, ultimately regulating macrophage function. Studies have demonstrated that itaconate acts on various signaling pathways, including Keap1-nuclear factor E2-related factor 2-ARE pathways, ATF3-IκBζ axis, and the stimulator of interferon genes (STING) pathway to exert antiinflammatory and antioxidant effects. Furthermore, several studies have reported that itaconate affects cancer occurrence and development through diverse signaling pathways. In this paper, we provide a comprehensive review of the role IRG1/itaconate and its derivatives in the regulation of macrophage metabolism and functions. By furthering our understanding of itaconate, we intend to shed light on its potential for treating inflammatory diseases and offer new insights in this field.

The Evolution and Ecology of Oxidative and Antioxidant Status: A Comparative Approach in African Mole-Rats

The naked mole-rat of the family Bathyergidae has been the showpiece for ageing research as they contradict the traditional understanding of the oxidative stress theory of ageing. Some other bathyergids also possess increased lifespans, but there has been a remarkable lack of comparison between species within the family Bathyergidae. This study set out to investigate how plasma oxidative markers (total oxidant status (TOS), total antioxidant capacity (TAC), and the oxidative stress index (OSI)) differ between five species and three subspecies of bathyergids, differing in their maximum lifespan potential (MLSP), resting metabolic rate, aridity index (AI), and sociality. We also investigated how oxidative markers may differ between captive and wild-caught mole-rats. Our results reveal that increased TOS, TAC, and OSI are associated with increased MLSP. This pattern is more prevalent in the social-living species than the solitary-living species. We also found that oxidative variables decreased with an increasing AI and that wild-caught individuals typically have higher antioxidants. We speculate that the correlation between higher oxidative markers and MLSP is due to the hypoxia-tolerance of the mole-rats investigated. Hormesis (the biphasic response to oxidative stress promoting protection) is a likely mechanism behind the increased oxidative markers observed and promotes longevity in some members of the Bathyergidae family.

Gender Differences in Oxidative Stress in Relation to Cancer Susceptibility and Survival

Genetic, developmental, biochemical, and environmental variables interact intricately to produce sex differences. The significance of sex differences in cancer susceptibility is being clarified by numerous studies. Epidemiological research and cancer registries have revealed over the past few years that there are definite sex variations in cancer incidence, progression, and survival. However, oxidative stress and mitochondrial dysfunction also have a significant impact on the response to treatment of neoplastic diseases. Young women may be more protected from cancer than men because most of the proteins implicated in the regulation of redox state and mitochondrial function are under the control of sexual hormones. In this review, we describe how sexual hormones control the activity of antioxidant enzymes and mitochondria, as well as how they affect several neoplastic diseases. The molecular pathways that underlie the gender-related discrepancies in cancer that have been identified may be better understood, which may lead to more effective precision medicine and vital information on treatment options for both males and females with neoplastic illnesses.

Sex differences in markers of oxidation and inflammation. Implications for ageing

Sexual dimorphism is a key factor to consider in the ageing process given the impact that it has on life expectancy. The oxidative-inflammatory theory of ageing states that the ageing process is the result of the establishment of oxidative stress which, due to the interplay of the immune system, translates into inflammatory stress, and that both processes are responsible for the damage and loss of function of an organism. We show that there are relevant gender differences in a number of oxidative and inflammatory markers and propose that they may account for the differential lifespan between sexes, given that males display, in general, higher oxidation and basal inflammation. In addition, we explain the significant role of circulating cell-free DNA as a marker of oxidative damage and an inductor of inflammation, connecting both processes and having the potential to become a useful ageing marker. Finally, we discuss how oxidative and inflammatory changes take place differentially with ageing in each sex, which could also have an impact on the sex-differential lifespan. Further research including sex as an essential variable is needed to understand the grounds of sex differences in ageing and to better comprehend ageing itself.

Defining the link between oxidative stress, behavioural reproductive suppression and heterothermy in the Natal mole-rat (Cryptomys hottentotus natalensis)

Sub-lethal effects, such as oxidative stress, can be linked to various breeding and thermophysiological strategies, which themselves can be linked to seasonal variability in abiotic factors. In this study, we investigated the subterranean, social living Natal mole-rat (Cryptomys hottentotus natalensis), which, unlike other social mole-rat species, implements heterothermy seasonally in an attempt to avoid exercise-induced hyperthermia and relies solely on behavioural reproductive suppression to maintain reproductive skew in colonies. Subsequently, we investigated how oxidative stress varied between season, sex and breeding status in Natal mole-rats. Oxidative markers included total oxidant status (TOS measure of total peroxides present), total antioxidant capacity (TAC), OSI (oxidative stress index) and malondialdehyde (MDA) to measure oxidative stress. Breeding and non-breeding mole-rats of both sexes were captured during the summer (wet season) and winter (dry season). Seasonal environmental variables (air temperature, soil temperature and soil moisture) had a significant effect on TOS, OSI and MDA, where season affected each sex differently. Unlike other social mole-rat species that use both physiological and behavioural means of reproductive suppression, no oxidative costs to reproduction were present in the Natal mole-rats. Males had significantly higher MDA than females, which was most apparent in summer (wet season). We conclude that the significant oxidative damage in males is a consequence of exercise-induced oxidative stress, exacerbated by increased burrow humidities and poorer heat dissipation abilities as a function of body mass. This study highlights the importance of both breeding and thermophysiological strategies in affecting oxidative stress.

Does high mitochondrial efficiency carry an oxidative cost? The case of the African pygmy mouse (Mus mattheyi)

Skeletal muscle mitochondria of the African pygmy mouse Mus mattheyi exhibit markedly reduced oxygen consumption and ATP synthesis rates but a higher mitochondrial efficiency than what would be expected from allometric trends. In the present study, we assessed whether such reduction of mitochondrial activity in M. mattheyi can limit the oxidative stress associated with an increased generation of mitochondrial reactive oxygen species. We conducted a comparative study of mitochondrial oxygen consumption, H₂O₂ release, and electron leak (%H₂O₂/O) in skeletal muscle mitochondria isolated from the extremely small African pygmy mouse (M. mattheyi, ~5 g) and Mus musculus, which is a larger Mus species (~25 g). Mitochondria were energized with pyruvate, malate, and succinate, after which fluxes were measured at different steady-state rates of oxidative phosphorylation. Overall, M. mattheyi exhibited lower oxidative activity and higher electron leak than M. musculus, while the H₂O₂ release did not differ significantly between these two Mus species. We further found that the high coupling efficiency of skeletal muscle mitochondria from M. mattheyi was associated with high electron leak. Nevertheless, data also show that, despite the higher electron leak, the lower mitochondrial respiratory capacity of M. mattheyi limits the cost of a net increase in H₂O₂ release, which is lower than that expected for a mammals of this size.

Precision Redox: The Key for Antioxidant Pharmacology

Significance: The redox balance of cells provides a stable microenvironment for biological macromolecules to perform their physiological functions. As redox imbalance is closely related to the occurrence and development of a variety of diseases, antioxidant therapies are an attractive option. However, redox-based therapeutic strategies have not yet shown satisfactory results. To find the key reason is of great significance. Recent Advances: We emphasize the precise nature of redox regulation and elucidate the importance and necessity of precision redox strategies from three aspects: differences in redox status, differences in redox function, and differences in the effects of redox therapy. We then propose the "5R" principle of precision redox in antioxidant pharmacology: "Right species, Right place, Right time, Right level, and Right target." Critical Issues: Redox status must be considered in the context of species, time, place, level, and target. The function of a biomacromolecule and its cellular signaling role are closely dependent on redox status. Accurate evaluation of redox status and specific interventions are critical for the success of redox treatments. Precision redox is the key for antioxidant pharmacology. The precise application of antioxidants as nutritional supplements is also key to the general health of the population. Future Directions: Future studies to develop more accurate methods for detecting redox status and accurately evaluating the redox state of different physiological and pathological processes are needed. Antioxidant pharmacology should consider the "5R" principle rather than continuing to apply global nonspecific antioxidant treatments. Antioxid. Redox Signal. 34, 1069-1082.

Beneficial and Detrimental Effects of Reactive Oxygen Species on Lifespan: A Comprehensive Review of Comparative and Experimental Studies

Aging is the greatest risk factor for a multitude of diseases including cardiovascular disease, neurodegeneration and cancer. Despite decades of research dedicated to understanding aging, the mechanisms underlying the aging process remain incompletely understood. The widely-accepted free radical theory of aging (FRTA) proposes that the accumulation of oxidative damage caused by reactive oxygen species (ROS) is one of the primary causes of aging. To define the relationship between ROS and aging, there have been two main approaches: comparative studies that measure outcomes related to ROS across species with different lifespans, and experimental studies that modulate ROS levels within a single species using either a genetic or pharmacologic approach. Comparative studies have shown that levels of ROS and oxidative damage are inversely correlated with lifespan. While these studies in general support the FRTA, this type of experiment can only demonstrate correlation, not causation. Experimental studies involving the manipulation of ROS levels in model organisms have generally shown that interventions that increase ROS tend to decrease lifespan, while interventions that decrease ROS tend to increase lifespan. However, there are also multiple examples in which the opposite is observed: increasing ROS levels results in extended longevity, and decreasing ROS levels results in shortened lifespan. While these studies contradict the predictions of the FRTA, these experiments have been performed in a very limited number of species, all of which have a relatively short lifespan. Overall, the data suggest that the relationship between ROS and lifespan is complex, and that ROS can have both beneficial or detrimental effects on longevity depending on the species and conditions. Accordingly, the relationship between ROS and aging is difficult to generalize across the tree of life.

Amyloid Beta-Peptide Increases BACE1 Translation through the Phosphorylation of the Eukaryotic Initiation Factor-2α

Alzheimer's disease (AD) is tightly linked to oxidative stress since amyloid beta-peptide (Aβ) aggregates generate free radicals. Moreover, the aggregation of Aβ is increased by oxidative stress, and the neurotoxicity induced by the oligomers and fibrils is in part mediated by free radicals. Interestingly, it has been reported that oxidative stress can also induce BACE1 transcription and expression. BACE1 is the key enzyme in the cleavage of the amyloid precursor protein to produce Aβ, and the expression of this enzyme has been previously shown to be enhanced in the brains of Alzheimer's patients. Here, we have found that BACE1 expression is increased in the hippocampi from AD patients at both the early (Braak stage II) and late (Braak stage VI) stages of the disease as studied by immunohistochemistry and western blot. To address the role of Aβ and oxidative stress in the regulation of BACE1 expression, we have analyzed the effect of subtoxic concentrations of Aβ oligomers (0.25 μM) and H₂O₂ (10 mM) on a human neuroblastoma cell line. Firstly, our results show that Aβ oligomers and H₂O₂ induce an increase of BACE1 mRNA as we studied by qPCR. Regarding BACE1 translation, it is dependent on the phosphorylation of the eukaryotic initiation factor 2α (eIF2α), since BACE1 mRNA bears a 5′UTR that avoids its translation under basal conditions. BACE1 5′UTR contains four upstream initiating codons (uAUGs), and its translation is activated when eIF2α is phosphorylated. Consistently, we have obtained that Aβ oligomers and H₂O₂ increase the levels of BACE1 and p-eIF2α assayed by western blot and confocal microscopy. Our results suggest that Aβ oligomers increase BACE1 translation by phosphorylating eIF2α in a process that involves oxidative stress and conforms a pathophysiological loop, where the Aβ once aggregated favors its own production continuously by the increase in BACE1 expression as observed in AD patients.

Dietary grape seed procyanidins suppressed weaning stress by improving antioxidant enzyme activity and mRNA expression in weanling piglets

This study was conducted to investigate the effect of grape seed procyanidins (GSP) on growth performance, digestive enzyme activity, antioxidant enzyme activity and mRNA expression in weanling piglets. A total of 96 piglets (Pietrain × Large White) with an average initial body weight (BW) of 8.4 ± 1.7 kg were weaned at 28 days, and randomly divided into 4 groups. Four groups of animals were fed with a basic diet supplemented with various doses of GSP (0, 40, 70 and 100 mg/kg respectively) during the 28-day treatment period. The results showed that the group receiving 40 mg/kg GSP significantly increased the average daily gain (ADG, p < .05) and decrease the feed/gain ratio (F/G, p < .05). Interestingly, the incidence of diarrhoea was significantly reduced in the groups of 40 and 70 mg/kg GSP, but it was increased in the group of 100 mg/kg GSP. Subsequent biochemical studies indicated that dietary GSP significantly increased the activities of digestive enzymes and antioxidant enzymes, including amylase (Amy), lipase(LPS, p < .05), glutathione peroxidase activity (GSH-Px, p < .05), superoxide dismutase activity (SOD, p < .05) and total antioxidant capacity (T-AOC, p < .05) in serum, liver and muscle, increased the expression of GSH-Px, SOD and CAT genes (p < .05) in the liver, and decreased the level of malondialdehyde (MDA, p < .05) in serum, liver and muscle. Taken together, these studies revealed that low GSP supplement in diets can improve growth performance of weaned piglets, which is associated with increased digestive and antioxidant enzyme activities and enhanced resistance to weanling stress.

Slow aging in mammals-Lessons from African mole-rats and bats

Traditionally, the main mammalian models used in aging research have been mice and rats, i.e. short-lived species that obviously lack effective maintenance mechanisms to keep their soma in a functional state for prolonged periods of time. It is doubtful that life-extending mechanisms identified only in such short-lived species adequately reflect the diversity of longevity pathways that have naturally evolved in mammals, or that they have much relevance for long-lived species such as humans. Therefore, some complementary, long-lived mammalian models have been introduced to aging research in the past 15-20 years, particularly naked mole-rats (and to a lesser extent also other mole-rats) and bats. Here, I summarize and compare the most important results regarding various aspects of aging - oxidative stress, molecular homeostasis and repair, and endocrinology - that have been obtained from studies using these new mammalian models of high longevity. I argue that the inclusion of these models was an important step forward, because it drew researchers' attention to certain oversimplifications of existing aging theories and to several features that appear to be universal components of enhanced longevity in mammals. However, even among mammals with high longevity, considerable variation exists with respect to other candidate mechanisms that also must be taken into account if inadequate generalizations are to be avoided.

The effects of graded levels of calorie restriction: II. Impact of short term calorie and protein restriction on circulating hormone levels, glucose homeostasis and oxidative stress in male C57BL/6 mice

Limiting food intake attenuates many of the deleterious effects of aging, impacting upon healthspan and leading to an increased lifespan. Whether it is the overall restriction of calories (calorie restriction: CR) or the incidental reduction in macronutrients such as protein (protein restriction: PR) that mediate these effects is unclear. The impact of 3 month CR or PR, (10 to 40%), on C57BL/6 mice was compared to controls fed ad libitum. Reductions in circulating leptin, tumor necrosis factor-α and insulin-like growth factor-1 (IGF-1) were relative to the level of CR and individually associated with morphological changes but remained unchanged following PR. Glucose tolerance and insulin sensitivity were improved following CR but not affected by PR. There was no indication that CR had an effect on oxidative damage, however CR lowered antioxidant activity. No biomarkers of oxidative stress were altered by PR. CR significantly reduced levels of major urinary proteins suggesting lowered investment in reproduction. Results here support the idea that reduced adipokine levels, improved insulin/IGF-1 signaling and reduced reproductive investment play important roles in the beneficial effects of CR while, in the short-term, attenuation of oxidative damage is not applicable. None of the positive effects were replicated with PR.

Effect of ageing and oxidative stress on antioxidant enzyme activity in different regions of the rat kidney

Oxidative stress has been implicated in ageing and the pathogenesis of chronic kidney disease. We examined levels of antioxidant enzymes glutathione peroxidase, glutathione reductase, glutathione S-transferase, catalase and superoxide dismutase as modulated by age and oxidative stress in different regions of the kidney. Antioxidant enzymes were examined in different regions of the kidney in male Wistar rats. Kidneys from rats of different ages (5, 12, 36 and 60 weeks) were dissected into cortex, outer medulla and inner medulla. Tissues were incubated for 30 min with or without 0.2 mM H2O2 to induce oxidative stress. Antioxidant enzyme activities progressively decreased with age under both control and stress conditions (P < 0.05) after peaking at 12 weeks. Antioxidant enzyme activities were greater in the cortex (P < 0.05) by comparison with the outer and inner medulla, respectively.

Updating the mitochondrial free radical theory of aging: an integrated view, key aspects, and confounding concepts

An updated version of the mitochondrial free radical theory of aging (MFRTA) and longevity is reviewed. Key aspects of the theory are emphasized. Another main focus concerns common misconceptions that can mislead investigators from other specialties, even to wrongly discard the theory. Those different issues include (i) the main reactive oxygen species (ROS)-generating site in the respiratory chain in relation to aging and longevity: complex I; (ii) the close vicinity or even contact between that site and the mitochondrial DNA, in relation to the lack of local efficacy of antioxidants and to sub-cellular compartmentation; (iii) the relationship between mitochondrial ROS production and oxygen consumption; (iv) recent criticisms on the MFRTA; (v) the widespread assumption that ROS are simple "by-products" of the mitochondrial respiratory chain; (vi) the unnecessary postulation of "vicious cycle" hypotheses of mitochondrial ROS generation which are not central to the free radical theory of aging; and (vii) the role of DNA repair concerning endogenous versus exogenous damage. After considering the large body of data already available, two general characteristics responsible for the high maintenance degree of long-lived animals emerge: (i) a low generation rate of endogenous damage: and (ii) the possession of tissue macromolecules that are highly resistant to oxidative modification.

Brain glucose-6-phosphate dehydrogenase protects against endogenous oxidative DNA damage and neurodegeneration in aged mice

Glucose-6-phosphate dehydrogenase (G6PD) protects the embryo from endogenous and xenobiotic-enhanced oxidative DNA damage and embryopathies. Here we show in aged mice that G6PD similarly protects against endogenous reactive oxygen species (ROS)-mediated neurodegeneration. In G6PD-normal (G6PD(+/+)) and heterozygous (G6PD(+/def)) and homozygous (G6PD(def/def)) G6PD-deficient male and female mice at about 2 years of age, oxidative DNA damage in various brain regions was assessed by 8-oxo-2'-deoxyguanosine formation using high-performance liquid chromatography and immunohistochemistry. Morphological changes in brain sections were assessed by H&E staining. DNA oxidation was increased in G6PD(def/def) mice in the cortex (p < 0.02), hippocampus (p < 0.01) and cerebellum (p < 0.006) compared to G6PD(+/+) mice, and was localized to distinct cell types. Histologically, in G6PD(+/def) mice, enhanced regionally and cellularly specific neurodegenerative changes were observed in those brain regions exhibiting elevated DNA oxidation, with a 53% reduction in the Purkinje cell count. These results show G6PD is important in protecting against the neurodegenerative effects of endogenous ROS in aging, and suggest that common hereditary G6PD deficiencies may constitute a risk factor for some neurodegenerative diseases.

The free-radical theory of ageing--older, wiser and still alive: modelling positional effects of the primary targets of ROS reveals new support

The continuing viability of the free-radical theory of ageing has been questioned following apparently incompatible recent results. We show by modelling positional effects of the generation and primary targets of reactive oxygen species that many of the apparently negative results are likely to be misleading. We conclude that there is instead a need to look more closely at the mechanisms by which free radicals contribute to age-related dysfunction in living systems. There also needs to be deeper understanding of the dynamics of accumulation and removal of the various kinds of molecular damage, in particular mtDNA mutations. Finally, the expectation that free-radical damage on its own might cause ageing needs to be relinquished in favour of the recognition that the free-radical theory is just one of the multiple mechanisms driving the ageing process.

The redox stress hypothesis of aging

The main objective of this review is to examine the role of endogenous reactive oxygen/nitrogen species (ROS) in the aging process. Until relatively recently, ROS were considered to be potentially toxic by-products of aerobic metabolism, which, if not eliminated, may inflict structural damage on various macromolecules. Accrual of such damage over time was postulated to be responsible for the physiological deterioration in the postreproductive phase of life and eventually the death of the organism. This "structural damage-based oxidative stress" hypothesis has received support from the age-associated increases in the rate of ROS production and the steady-state amounts of oxidized macromolecules; however, there are increasing indications that structural damage alone is insufficient to satisfactorily explain the age-associated functional losses. The level of oxidative damage accrued during aging often does not match the magnitude of functional losses. Although experimental augmentation of antioxidant defenses tends to enhance resistance to induced oxidative stress, such manipulations are generally ineffective in the extension of life span of long-lived strains of animals. More recently, in a major conceptual shift, ROS have been found to be physiologically vital for signal transduction, gene regulation, and redox regulation, among others, implying that their complete elimination would be harmful. An alternative notion, advocated here, termed the "redox stress hypothesis," proposes that aging-associated functional losses are primarily caused by a progressive pro-oxidizing shift in the redox state of the cells, which leads to the overoxidation of redox-sensitive protein thiols and the consequent disruption of the redox-regulated signaling mechanisms.

Gadd45 proteins: relevance to aging, longevity and age-related pathologies

The Gadd45 proteins have been intensively studied, in view of their important role in key cellular processes. Indeed, the Gadd45 proteins stand at the crossroad of the cell fates by controlling the balance between cell (DNA) repair, eliminating (apoptosis) or preventing the expansion of potentially dangerous cells (cell cycle arrest, cellular senescence), and maintaining the stem cell pool. However, the biogerontological aspects have not thus far received sufficient attention. Here we analyzed the pathways and modes of action by which Gadd45 members are involved in aging, longevity and age-related diseases. Because of their pleiotropic action, a decreased inducibility of Gadd45 members may have far-reaching consequences including genome instability, accumulation of DNA damage, and disorders in cellular homeostasis - all of which may eventually contribute to the aging process and age-related disorders (promotion of tumorigenesis, immune disorders, insulin resistance and reduced responsiveness to stress). Most recently, the dGadd45 gene has been identified as a longevity regulator in Drosophila. Although further wide-scale research is warranted, it is becoming increasingly clear that Gadd45s are highly relevant to aging, age-related diseases (ARDs) and to the control of life span, suggesting them as potential therapeutic targets in ARDs and pro-longevity interventions.

Differential susceptibility of a few members of thenasuta–albomicanscomplex ofDrosophilato paraquat-induced lethality and oxidative stress

The evolution of karyotypically stabilized short-lived (SL) and long-lived (LL) cytoraces in the laboratory have been established and validated through our previous lifespan studies. In the present investigation, we examined the possible reason(s) for the differential longevity among selected members of SL and LL cytoraces, employing the well known paraquat (PQ) resistance bioassay. Exposure of these races to varying concentrations of PQ revealed relatively higher resistance among LL cytoraces than SL cytoraces, as evident by the lower incidence of mortality. Biochemical analysis for endogenous markers of oxidative stress revealed that LL-2 cytorace exhibited lower reactive oxygen species (ROS) and lipid peroxidation (LPO) levels, higher activity levels of superoxide dismutase (SOD), and coupled with higher levels of reduced glutathione (GSH) compared with the levels found in SL-2 cytorace. These findings suggest that the higher susceptibility of SL cytoraces to PQ challenge may be, at least in part, related to the higher endogenous levels of oxidative stress markers. Although the precise mechanisms responsible for the longer longevity among LL cytoraces of the nasuta–albomicans complex of Drosophila merits further investigation, our data suggest that the relatively longer lifespan may be related to the status of endogenous markers that renders them more resistant towards oxidative-stress-mediated lethality, as evident in the PQ assay.

Noninvasive quantification of ascorbate and glutathione concentration in the elderly human brain

In this study, ascorbate (Asc) and glutathione (GSH) concentrations were quantified noninvasively using double-edited (1)H MRS at 4 T in the occipital cortex of healthy young [age (mean ± standard deviation) = 20.4 ± 1.4 years] and elderly (age = 76.6 ± 6.1 years) human subjects. Elderly subjects had a lower GSH concentration than younger subjects (p < 0.05). The Asc concentration was not significantly associated with age. Furthermore, the lactate (Lac) concentration was higher in elderly than young subjects. Lower GSH and higher Lac concentrations are indications of defective protection against oxidative damage and impaired mitochondrial respiration. The extent to which the observed concentration differences could be associated with physiological differences and methodological artifacts is discussed. In conclusion, GSH and Asc concentrations were compared noninvasively for the first time in young vs elderly subjects.

Increase of Drosophila melanogaster lifespan due to D-GADD45 overexpression in the nervous system

The GADD45 protein family plays an important role in stress signaling and participates in the integration of cellular response to environmental and physiological factors. GADD45 proteins are involved in cell cycle control, DNA repair, apoptosis, cell survival and aging, and inflammatory response by complicated protein-protein interactions. In Drosophila melanogaster a single D-GADD45 ortholog (GG1086) has been described. Our data show that overexpression of the D-GADD45 gene in the nervous system leads to a significantly increase of Drosophila lifespan without a decrease in fecundity and locomotor activity. The lifespan extension effect is more pronounced in males than in females, which agrees with the sex-dependent expression of this gene. The longevity of D. melanogaster with D-GADD45 overexpression is apparently due to more efficient recognition and repair of DNA damage, as the DNA comet assay showed that the spontaneous DNA damage in the larva neuroblasts is reduced with statistical significance.

Comparative cellular biogerontology: primer and prospectus

Most prior work on the biological basis of aging has focused on describing differences between young and old individuals but provided only limited insight into the mechanisms controlling the rate of aging. Natural selection has produced a goldmine of experimental material, in the form of species of differing aging rate, whose longevity can vary by 10-fold or more within mammalian orders, but these resources remain largely unexplored at the cellular level. In this review article we focus on one approach to comparative biogerontology: the strategy of evaluating the properties of cultured cells from organisms of varying lifespan and aging rate. In addition, we discuss problems associated with the analysis and interpretations of interspecific variation of cellular trait data among species with disparate longevity. Given the impressive array of 'natural experiments' in aging rate, overcoming the technical and conceptual obstacles confronting research in comparative cellular gerontology will be well worth the effort.

Reduced DNA oxidation in aged prostaglandin H synthase-1 knockout mice

Prostaglandin H synthase (PHS)-2 (COX-2) is implicated in the neurodegeneration of Alzheimer and Parkinson diseases. Multiple mechanisms may be involved, including PHS-catalyzed bioactivation of neurotransmitters, precursors, and metabolites to neurotoxic free radical intermediates. Herein, in vitro studies with the purified PHS-1 (COX-1) isoform and in vivo studies of aging PHS-1 knockout mice were used to evaluate the potential neurodegenerative role of PHS-1-catalyzed bioactivation of endogenous neurotransmitters to free radical intermediates that enhance reactive oxygen species formation and oxidative DNA damage. The brains of 2-year-old wild-type (+/+) PHS-1 normal and heterozygous (+/-) and homozygous (-/-) PHS-1 knockout mice were analyzed for 8-oxo-2'-deoxyguanosine formation, characterized by high-performance liquid chromatography with electrochemical detection and by immunohistochemistry. Compared to aging PHS-1(+/+) normal mice, aging PHS-1(-/-) knockout mice had less oxidative DNA damage in the cortex, hippocampus, cerebellum, and brain stem. This PHS-1-dependent oxidative damage was not observed in young mice. In vitro incubation of purified PHS-1 and 2'-deoxyguanosine with dopamine, L-DOPA, and epinephrine, but not glutamate or norepinephrine, enhanced oxidative DNA damage. These results suggest that PHS-1-dependent accumulation of oxidatively damaged macromolecules including DNA may contribute to the mechanisms and risk factors of aging-related neurodegeneration.

Antioxidant enzyme activities are not broadly correlated with longevity in 14 vertebrate endotherm species

The free radical theory of ageing posits that accrual of oxidative damage underlies the increased cellular, tissue and organ dysfunction and failure associated with advanced age. In support of this theory, cellular resistance to oxidative stress is highly correlated with life span, suggesting that prevention or repair of oxidative damage might indeed be essential for longevity. To test the hypothesis that the prevention of oxidative damage underlies longevity, we measured the activities of the five major intracellular antioxidant enzymes in brain, heart and liver tissue of 14 mammalian and avian species with maximum life spans (MLSPs) ranging from 3 years to over 100 years. Our data set included Snell dwarf mice in which life span is increased by approximately 50% compared to their normal littermates. We found that CuZn superoxide dismutase, the major cytosolic superoxide dismutase, showed no correlation with MLSP in any of the three organs. Similarly, neither glutathione peroxidase nor glutathione reductase activities correlated with MLSP. MnSOD, the sole mitochondrial superoxide dismutase in mammals and birds, was positively correlated with MLSP only for brain tissue. This same trend was observed for catalase. For all correlational data, effects of body mass and phylogenetic relatedness were removed using residual analysis and Felsenstein's phylogenetically independent contrasts. Our results are not consistent with a causal role for intracellular antioxidant enzymes in longevity, similar to recent reports from studies utilising genetic modifications of mice (Pérez et al., Biochim Biophys Acta 1790:1005-1014, 2009). However, our results indicate a specific augmentation of reactive oxygen species neutralising activities in brain associated with longevity.

Cardioprotective effect of EGb 761 on myocardial ultrastructure of young and old rat heart and antioxidant status during acute hypoxia

BACKGROUND AND AIMS

Acute hypoxia is a threatening clinical case of emergency and may result in ultrastructural damage, with complete loss of cellular and organ functions. However, little is known about the differences in hypoxia tolerance between young and old myocardia and the protective effects of radical scavenging agents in acute hypoxic stress situations.

METHODS

We investigated the age-dependent differences of the myocardial ultrastructure and antioxidative status (superoxide-dismutase (SOD) activity and malondialdehyde (MDA) content) of young (6 months) and old (22-24 months) Wistar rats (Crl (Wi)Br) after acute respiratory hypoxia of 20 min at 5% v/v O2 in N2O mixture, and the protective effect of Ginkgo biloba extract (EGb 761).

RESULTS

Ultrastructural-morphometric and biochemical age analysis only revealed a decrease in the sarcoplasma volume fraction, an increase in homogeneous intramitochondrial areas, significant higher SOD activity and lower MDA levels in the group of old rats. Pretreatment with EGb 761 led to a significant decrease in MDA content in both control groups. Acute hypoxic stress increased the volume fractions of sarcoplasmatic reticulum, t-tubules, vacuoles, and lipid droplets, and caused mitochondrial swelling, with a more significant increase in degenerated and homogeneous intramitochondrial areas in the old group. SOD activity decreased only in the old hypoxic group; MDA content fell in both. Pretreatment with EGb 761 reduced ultrastructural-morphometric hypoxic damage in both groups, significantly below the levels of control. Young rat myocardium showed significantly higher SOD activity after hypoxia than untreated or older specimens.

CONCLUSIONS

Better hypoxia tolerance is demonstrated by the young myocardium, and an obvious hypoxia-protective effect of EGb 761 in both age groups.

The long lifespan of two bat species is correlated with resistance to protein oxidation and enhanced protein homeostasis

Altered structure, and hence function, of cellular macromolecules caused by oxidation can contribute to loss of physiological function with age. Here, we tested whether the lifespan of bats, which generally live far longer than predicted by their size, could be explained by reduced protein damage relative to short-lived mice. We show significantly lower protein oxidation (carbonylation) in Mexican free-tailed bats (Tadarida brasiliensis) relative to mice, and a trend for lower oxidation in samples from cave myotis bats (Myotis velifer) relative to mice. Both species of bat show in vivo and in vitro resistance to protein oxidation under conditions of acute oxidative stress. These bat species also show low levels of protein ubiquitination in total protein lysates along with reduced proteasome activity, suggesting diminished protein damage and removal in bats. Lastly, we show that bat-derived protein fractions are resistant to urea-induced protein unfolding relative to the level of unfolding detected in fractions from mice. Together, these data suggest that long lifespan in some bat species might be regulated by very efficient maintenance of protein homeostasis.

Testing hypotheses of aging in long-lived mice of the genus Peromyscus: association between longevity and mitochondrial stress resistance, ROS detoxification pathways, and DNA repair efficiency

In the present review we discuss the potential use of two long-lived mice of the genus Peromyscus--the white-footed mouse (P. leucopus) and the deer mouse (P. maniculatus) maximum lifespan potential approximately 8 years for both--to test predictions of theories about aging from the oxidative stress theory, mitochondrial theory and inflammatory theory. Previous studies have shown that P. leucopus cells exhibit superior antioxidant defense mechanisms and lower cellular production of reactive oxygen species (ROS) than do cells of the house mouse, Mus musculus (maximum lifespan approximately 3.5 years). We present new data showing that mitochondria in P. leucopus cells produce substantially less ROS than mitochondria in M. musculus cells, and that P. leucopus mitochondria exhibit superior stress resistance to those of M. musculus. We also provide evidence that components of the DNA repair system (e.g., pathways involved in repair of DNA damage induced by gamma-irradiation) are likely to be more efficient in P. leucopus than in M. musculus. We propose that mitochondrial stress resistance, ROS detoxification pathways and more efficient DNA repair contribute to the previously documented resistance of P. leucopus cells toward oxidative stress-induced apoptosis. The link between these three pathways and species longevity is discussed.

Age-related increase of superoxide generation in the brains of mammals and birds

Oxidative stress, an imbalance between endogenous levels of oxygen radicals and antioxidative defense, increases with aging. However, it is not clear which of these two factors is the more critical. To clarify the production of oxygen radicals increases with age, we examined oxygen radical-dependent chemiluminescent signals in ex vivo brain slices using a novel photonic imaging method. The chemiluminescent intensity was significantly decreased by the membrane permeable superoxide dismutase (SOD)/catalase mimic, but not by Cu,Zn-SOD. Inhibitors for complex I, III, and IV of the mitochondrial electron transport chain transiently enhanced the chemiluminescent signal. The superoxide-dependent chemiluminescent intensity in senescence accelerated mouse (SAM) brain tissues increases with age. Moreover, the slope of the age-dependent increase was steeper in SAMP10, a strain characterized by a short lifespan and atrophy in the frontal cerebral cortex, than the senescence-resistant strain SAMR1, which has a longer lifespan. An increase in chemiluminescence with age was also observed in C57/BL6 mice, Wistar rats, and pigeons, although levels of chemiluminescence were lower in the pigeons than murines. The rate of age-related increases of superoxide-dependent chemiluminescence was inversely related to the maximum lifespan of the animals. The activity of superoxide dismutase was unchanged during the aging process in the brain. This suggested that superoxide production itself may increase with age. We speculated that reactive oxygen may be a signal to determine the aging process.

Fibroblasts from naked mole-rats are resistant to multiple forms of cell injury, but sensitive to peroxide, ultraviolet light, and endoplasmic reticulum stress

Fibroblasts from long-lived mutant mice are resistant to many forms of lethal injury as well as to the metabolic effects of rotenone and low-glucose medium. Here we evaluated fibroblasts from young adult naked mole-rats (NMR; Heterocephalus glaber), a rodent species in which maximal longevity exceeds 28 years. Compared to mouse cells, NMR cells were resistant to cadmium, methyl methanesulfonate, paraquat, heat, and low-glucose medium, consistent with the idea that cellular resistance to stress may contribute to disease resistance and longevity. Surprisingly, NMR cells were more sensitive than mouse cells to H(2)O(2), ultraviolet (UV) light, and rotenone. NMR cells, like cells from Snell dwarf mice, were more sensitive to tunicamycin and thapsigargin, which interfere with the function of the endoplasmic reticulum (ER stress). The sensitivity of both Snell dwarf and NMR cells to ER stress suggests that alterations in the unfolded protein response might modulate cell survival and aging rate.

Sex differences in survival and mitochondrial bioenergetics during aging in Drosophila

The goal of this study is to test the role of mitochondria and of mitochondrial metabolism in determining the processes that influence aging of female and male Drosophila. We observe that Drosophila simulans females tended to have shorter lifespan, higher levels of hydrogen peroxide production and significantly lower levels of catalase but not superoxide dismutase compared to males. In contrast, mammalian females tend to be longer lived, have lower rates of reactive oxygen species production and higher antioxidant activity. In both Drosophila and mammals, mitochondria extracted from females consume a higher quantity of oxygen when provided with adenosine diphosphate and have a greater mtDNA copy number than males. Combined, these data illustrate important similarities between the parameters that influence aging and mitochondrial metabolism in Drosophila and in mammals but also show surprising differences.

Low rates of hydrogen peroxide production by isolated heart mitochondria associate with long maximum lifespan in vertebrate homeotherms

An inverse correlation between free radical production by isolated mitochondria and longevity in homeotherms has been reported, but previous comparative studies ignored possible confounding effects of body mass and phylogeny. We investigated this correlation by comparing rates of hydrogen peroxide (H(2)O(2)) production by heart mitochondria isolated from groups or pairs of species selected to have very different maximum lifespans but similar body masses (small mammals, medium-sized mammals, birds). During succinate oxidation, H(2)O(2) production rates were generally lower in the longer-lived species; the differences arose at complex I of the electron transport chain during reverse electron transport. Additional data were obtained from large species and the final dataset comprised mouse, rat, white-footed mouse, naked mole-rat, Damara mole-rat, guinea pig, baboon, little brown bat, Brazilian free-tailed bat, ox, pigeon and quail. In this dataset, maximum lifespan was negatively correlated with H(2)O(2) production at complex I during reverse electron transport. Analysis of residual maximum lifespan and residual H(2)O(2) production revealed that this correlation was even more significant after correction for effects of body mass. To remove effects of phylogeny, independent phylogenetic contrasts were obtained from the residuals. These revealed an inverse association between maximum lifespan and H(2)O(2) production that was significant by sign test, but fell short of significance by regression analysis. These findings indicate that enhanced longevity may be causally associated with low free radical production by mitochondria across species over two classes of vertebrate homeotherms.

Sympatric Drosophila simulans flies with distinct mtDNA show age related differences in mitochondrial metabolism

The primary causes of age-related changes in mitochondrial metabolism are not known. The goal of this study is to document the influence of naturally occurring mtDNA variation on age dependent changes in mitochondrial respiration, hydrogen peroxide (H(2)O(2)) generation and antioxidant defenses in the fly Drosophila simulans. Possible changes include an increase in rates of reactive oxygen species production with age and/or an age dependent decrease in antioxidant response. For this study we have used flies harboring distinct siII and siIII mtDNA types. Previously we have shown that males harboring siII mtDNA had higher rates of mitochondrial H(2)O(2) production from complex III at 11d compared to males with the siIII mtDNA type. Here, we corroborate those results and show that Drosophila harboring the siII and siIII mtDNA types exhibit significantly different patterns of pro-oxidant and antioxidant activities as they age. Flies harboring siII mtDNA had higher rates of mitochondrial H(2)O(2) production and manganese superoxide dismutase activity at 11 and 18d of age than siIII mtDNA harboring flies. Copper-zinc superoxide dismutase activity increased from 11 to 25d in siII flies while the accumulation of oxidized glutathione did not change between 11 and 25d. In contrast, siIII harboring flies showed an age dependent increase in H(2)O(2) production, reaching higher production rates on day 25 than that observed in siII flies. Copper-zinc superoxide dismutase activities did not change between 11 and 25d while the oxidized glutathione accumulation increased with age. The results show antioxidant levels correlate with pro-oxidant levels in siII but not siIII flies. These results demonstrate our ability to correlate mtDNA variation with differences in whole mitochondrial physiology and individual complex biochemistry.

Comparison of age-related differences in expression of antioxidant enzyme mRNA and activity in various tissues of pigs

Antioxidant enzymes (AOEs), glutathione peroxidase (GPx), superoxide dismutase(SOD) and catalase (CAT) play an important role in protecting tissues from reactive oxygen species (ROS) reactions. The objective of this study was to determine the developmental regulation of AOEs mRNA levels and activity in tissues of different growing phases pigs (Sus scrofa). Nine different tissues were collected from thirty Duroc x Landrace x Yorkshire male pigs with six animals in each age (1, 42, 84, 126 and 168 days) to assay for GPx, CAT and CuZnSOD mRNA expression and activities. Results showed that GPx, CAT, and CuZnSOD mRNA levels in liver increased (P<0.05) at the first stage, and thereafter their levels began to decline (P<0.05), and the maximal mRNA levels of these AOEs were seen at the age of 42, 84, and 126 days, respectively. In Muscle, GPx and CAT mRNA level increased from 1 to 84 days and 1 to 126 days, respectively, and thereafter their levels began to decline, whereas CuZnSOD mRNA level steadily increased (P<0.05) following birth. Activity expression of AOEs in selected tissues was increased as pigs became older (P<0.05) with the exception of CuZnSOD activity in muscle, but changes in AOEs mRNA levels between ages did not fully account for all changes in activity. GPx and CuZnSOD mRNA were most abundantly expressed in muscle, while CAT mRNA were most abundant in brain. AOEs may exert cell and tissue-specific roles in metabolic regulation beyond their mere antioxidant potential. In conclusion, expression of AOEs mRNA and activity exhibit different developmental profiles in various tissues of pigs, and the regulation of AOEs is not tightly coordinated in either tissue.

Aging in vertebrates, and the effect of caloric restriction: a mitochondrial free radical production-DNA damage mechanism?

Oxygen is toxic to aerobic animals because it is univalently reduced inside cells to oxygen free radicals. Studies dealing with the relationship between oxidative stress and aging in different vertebrate species and in caloric-restricted rodents are discussed in this review. Healthy tissues mainly produce reactive oxygen species (ROS) at mitochondria. These ROS can damage cellular lipids, proteins and, most importantly, DNA. Although antioxidants help to control this oxidative stress in cells in general, they do not decrease the rate of aging, because their concentrations are lower in long- than in short-lived animals and because increasing antioxidant levels does not increase vertebrate maximum longevity. However, long-lived homeothermic vertebrates consistently have lower rates of mitochondrial ROS production and lower levels of steady-state oxidative damage in their mitochondrial DNA than short-lived ones. Caloric-restricted rodents also show lower levels of these two key parameters than controls fed ad libitum. The decrease in mitochondrial ROS generation of the restricted animals has been recently localized at complex I and the mechanism involved is related to the degree of electronic reduction of the complex I ROS generator. Strikingly, the same site and mechanism have been found when comparing a long- with a short-lived animal species. It is suggested that a low rate of mitochondrial ROS generation extends lifespan both in long-lived and in caloric-restricted animals by determining the rate of oxidative attack and accumulation of somatic mutations in mitochondrial DNA.

Skin-derived fibroblasts from long-lived species are resistant to some, but not all, lethal stresses and to the mitochondrial inhibitor rotenone

Fibroblast cell lines were developed from skin biopsies of eight species of wild-trapped rodents, one species of bat, and a group of genetically heterogeneous laboratory mice. Each cell line was tested in vitro for their resistance to six varieties of lethal stress, as well as for resistance to the nonlethal metabolic effects of the mitochondrial inhibitor rotenone and of culture at very low glucose levels. Standard linear regression of species-specific lifespan against each species mean stress resistance showed that longevity was associated with resistance to death induced by cadmium and hydrogen peroxide, as well as with resistance to rotenone inhibition. A multilevel regression method supported these associations, and suggested a similar association for resistance to heat stress. Regressions for resistance to cadmium, peroxide, heat, and rotenone remained significant after various statistical adjustments for body weight. In contrast, cells from longer-lived species did not show significantly greater resistance to ultraviolet light, paraquat, or the DNA alkylating agent methylmethanesulfonate. There was a strong correlation between species longevity and resistance to the metabolic effects of low-glucose medium among the rodent cell lines, but this test did not distinguish mice and rats from the much longer-lived little brown bat. These results are consistent with the idea that evolution of long-lived species may require development of cellular resistance to several forms of lethal injury, and provide justification for evaluation of similar properties in a much wider range of mammals and bird species.

Secrets of the lac operon. Glucose hysteresis as a mechanism in dietary restriction, aging and disease

Elevated blood glucose associated with diabetes produces progressive and apparently irreversible damage to many cell types. Conversely, reduction of glucose extends life span in yeast, and dietary restriction reduces blood glucose. Therefore it has been hypothesized that cumulative toxic effects of glucose drive at least some aspects of the aging process and, conversely, that protective effects of dietary restriction are mediated by a reduction in exposure to glucose. The mechanisms mediating cumulative toxic effects of glucose are suggested by two general principles of metabolic processes, illustrated by the lac operon but also observed with glucose-induced gene expression. First, metabolites induce the machinery of their own metabolism. Second, induction of gene expression by metabolites can entail a form of molecular memory called hysteresis. When applied to glucose-regulated gene expression, these two principles suggest a mechanism whereby repetitive exposure to postprandial excursions of glucose leads to an age-related increase in glycolytic capacity (and reduction in beta-oxidation of free fatty acids), which in turn leads to an increased generation of oxidative damage and a decreased capacity to respond to oxidative damage, independent of metabolic rate. According to this mechanism, dietary restriction increases life span and reduces pathology by reducing exposure to glucose and therefore delaying the development of glucose-induced glycolytic capacity.

Antioxidants do not explain the disparate longevity between mice and the longest-living rodent, the naked mole-rat

The maximum lifespan of naked mole-rats (NMRs; Heterocephalus glaber) is greater than that of any other rodent. These hystricognaths survive in captivity >28 years, eight-times longer than similar-sized mice. The present study tested if NMRs possess superior antioxidant defenses compared to mice and if age-related interspecies changes in antioxidants were evident. Activities of Cu/Zn superoxide dismutase (Cu/Zn, SOD), Mn SOD, catalase and cellular glutathione peroxidase (cGPx) were measured in livers of physiologically equivalent age-matched NMRs (30, 75 and 130 months) and CB6F1 mice (4, 12 and 18 months). In mice, Mn SOD activity increased with age, while the activity of catalase and cGPx declined. None of the antioxidants changed with age in mole-rats. cGPx activity of NMRs was 70-times lower (p < 0.0001) than in mice, and resembled that of cGPx knock-out animals. NMRs may partially compensate for the lower cGPx when compared to mice, by having moderately higher activities of the other antioxidants. It is nonetheless unlikely that antioxidant defenses are responsible for the eight-fold longevity difference between these two species. Maintenance of constant antioxidant defenses with age in NMRs concurs with previous physiological data, suggesting delayed aging in this species.

The biosynthesis of ascorbate protects isolated rat hepatocytes from cumene hydroperoxide-mediated oxidative stress

Most animals synthesize ascorbate. It is an essential enzymatic cofactor for the synthesis of a variety of biological molecules and also a powerful antioxidant. There is, however, little direct evidence supporting an antioxidant role for endogenously produced ascorbate. Recently, we demonstrated that incubation of rat hepatocytes with 1-bromoheptane or phorone simultaneously depleted glutathione (GSH) and triggered rapid ascorbate synthesis. The present study investigates the hypothesis that endogenous ascorbate synthesis can confer protection against oxidative stress. Rat and guinea pig hepatocytes were depleted of GSH with 1-bromoheptane and subsequently treated with the oxidative stressor cumene hydroperoxide (CHP) in the presence or absence of the ascorbate synthesis inhibitor sorbinil. In rat hepatocytes, ascorbate content increased linearly (from 15.1 to 35.8 nmol/10(6) cells) over a 105-min incubation. Prior depletion of GSH increased CHP-induced cellular reactive oxygen species (ROS) production, lipid peroxidation, and cell death in rat and guinea pig hepatocytes. Inhibiting ascorbate synthesis, however, further elevated ROS production (2-fold), lipid peroxidation (1.5-fold), and cell death (2-fold) in rat hepatocytes only. This is the first time that endogenous ascorbate synthesis has been shown to decrease cellular susceptibility to oxidative stress. Protection by endogenously produced ascorbate may therefore need to be addressed when extrapolating data to humans from experiments using rodents capable of synthesizing ascorbate.

Kinetic characteristics of native gamma-glutamylcysteine ligase in the aging housefly, Musca domestica L

The catalytic activity of gamma-glutamylcysteine ligase (gamma-GCL; EC 6.3.2.2) was compared between relatively young (4-day-old) and old (19-day-old) houseflies (Musca domestica) in order to understand the mechanism of putative deterioration of glutathione homeostasis during the aging process. Hanes-Woolf analyses ([S]/v vs [S]) indicated that gamma-GCL had significantly higher affinities for its substrates in the young than in the old flies. The K(m) values in the young and old flies were, respectively, for glutamate 0.6 and 5.5 mM; for cysteine 0.3 and 4.6 mM; and for ATP 1.2 and 2.9 mM. Furthermore, young but not old flies exhibited substrate-dependent inhibition of gamma-GCL activity at >5 mM cysteine indicating a loss of metabolic regulation during aging. The age-associated differences in the affinity of native gamma-GCL towards its substrates suggest that de novo synthesis of glutathione would be relatively less efficient in the old houseflies.

Exercise improves biomarkers of health and stress in animals fed ad libitum

Voluntary and forced exercise decrease morbidity and mortality in laboratory animals. Caloric restriction has similar effects on health and unique benefits on life span. Nonetheless, in most experiments, animals do not have access to physical activity and are fed ad libitum (AL). We hypothesized that with regular access to either unlimited running wheel exercise (EX) or limited physical activity (PA), key biomarkers of health would be enhanced enough to counter some consequences of a sedentary AL lifestyle. This 16-month study compared body weight, tumor number and size, tissue lesions, oxidative stress, and reactive stress in (1) sedentary animals with no access to physical activity (SED); (2) animals with access to hour-long, twice weekly activity in a large box (PA); and (3) animals with access every other day to a running wheel (EX). At the end of the study, EX body weight was 8-9% lower than PA and SED. In addition, EX had no kidney lesions versus 50% in PA and SED, and had smaller tumor size (10+/-2 vs. 14+/-4 and 30+/-4 mm). Exhaustive exercise lowered glutathione/oxidized glutathione ratio in EX and PA, but in SED, the ratio was depressed even in resting animals. In all treatments, prolactin (PRL) levels were lower in resting animals than in acutely exercised animals. In conclusion, EX had the most favorable health biomarkers while SED had the least. PA did not confer gross health benefits different than the SED group, but was biochemically more similar to EX animals.