Caloric restriction: powerful protection for the aging heart and vasculature

Cardiac-targeting magnetic lipoplex delivery of SH-IGF1R plasmid attenuate norepinephrine-induced cardiac hypertrophy in murine heart

Recent studies have demonstrated a number of molecular mechanisms contributing to the initiation of cardiac hypertrophy response to pressure overload. IGF1R (insulin-like growth factor-1 receptor), an important oncogene, is overexpressed in hypertrophic heart and mediates the hypertrophic pathology process. In this study, we applied with liposomal magnetofection that potentiated gene transfection by applying an external magnetic field to enhance its transfection efficiency. Liposomal magnetofection provided high efficiency in transgene expression in vivo. In vivo, IGF1R-specific-shRNA (small-hairpin RNA) by magnetofection inhibited IGF1R protein expression by 72.2 ± 6.8, 80.7 ± 9.6 and 84.5 ± 5.6%, at 24, 48 and 72 h, respectively, after pGFPshIGF1R injection, indicating that liposomal magnetofection is a promising method that allows the targeting of gene therapy for heart failure. Furthermore, we found that the treated animals (liposomal magnetofection with shIGF1R) showed reduced septal and posterior wall thickness, reduced HW:BWs (heart weight-to-body weights) compared with controls. Moreover, we also found that liposomal magnetofection-based shIGF1R transfection decreased the expression level of p-ERK (phosphorylated extracellular-signal-regulated kinase)1/2, p-AKT1 (phosphorylated protein kinase B1) compared with untreated hearts. These results suggested that liposomal magnetofection-mediated IGF1R-specific-shRNA may be a promising method, and suppression the IGF1R expression inhibited norepinephrine-induced cardiac hypertrophic process via inhibiting PI3K (phosphoinositide 3-kinase)/AKT pathway.

Heart failure with preserved ejection fraction: molecular pathways of the aging myocardium

Age-related diastolic dysfunction is a major factor in the epidemic of heart failure. In patients hospitalized with heart failure, HFpEF is now as common as heart failure with reduced ejection fraction. We now have many successful treatments for heart failure with reduced ejection fraction, while specific treatment options for HFpEF patients remain elusive. The lack of treatments for HFpEF reflects our very incomplete understanding of this constellation of diseases. There are many pathophysiological factors in HFpEF, but aging appears to play an important role. Here, we propose that aging of the myocardium is itself a specific pathophysiological process. New insights into the aging heart, including hormonal controls and specific molecular pathways, such as microRNAs, are pointing to myocardial aging as a potentially reversible process. While the overall process of aging remains mysterious, understanding the molecular pathways of myocardial aging has never been more important. Unraveling these pathways could lead to new therapies for the enormous and growing problem of HFpEF.

The influence of body mass index, age and sex on inflammatory disease risk in semi-captive Chimpanzees

Obesity and ageing are emerging issues in the management of captive primates, including Chimpanzees, Pan troglodytes. Studies on humans show that obesity and old age can independently increase the risk of inflammatory-associated diseases indicated by elevated levels of pro-inflammatory cells and proteins in the blood of older or obese compared to levels in younger or non-obese individuals. In humans, sex can influence the outcomes of these risks. Health management of these problems in chimpanzee populations requires an understanding of similarities and differences of factors influencing inflammatory disease risks in humans and in chimpanzees. We examined the relationship between age, sex and Body Mass Index (BMI) with hematological biomarkers of inflammatory disease risk established for humans which include the neutrophil to lymphocyte ratio (NLR), and neutrophil, white blood cell (WBC), platelet microparticle and platelet counts. We found that higher values of NLR, neutrophil count and platelet microparticle count were associated with higher BMI values and older age indicating increased inflammation risk in these groups; a similar pattern to humans. There was a strong sex by age interaction on inflammation risk, with older males more at risk than older females. In contrast to human studies, total WBC count was not influenced by BMI, but like humans, WBC and platelet counts were lower in older individuals compared to younger individuals. Our findings are similar to those of humans and suggest that further insight on managing chimpanzees can be gained from extensive studies of ageing and obesity in humans. We suggest that managing BMI should be an integral part of health management in captive chimpanzee populations in order to partially reduce the risk of diseases associated with inflammation. These results also highlight parallels in inflammation risk between humans and chimpanzees and have implications for understanding the evolution of inflammation related diseases in apes.

SIRT1 in cardiovascular aging

Cardiovascular disease (CVD) is the leading cause of death worldwide, with aging as the key independent risk factor. Effective interventions are necessary to delay aging. Sirtuin1 (SIRT1), a NAD(+)-dependent histone deacetylase, is closely related to lifespan extension. SIRT1 exerts beneficial effects on aging and age-related diseases, such as atherosclerosis. In this review, we summarize the current knowledge on the functions of SIRT1 in cardiovascular aging, focusing on the underlying molecular mechanisms, including inhibition of oxidative stress and inflammation, and induction of autophagy. We also demonstrate that moderate up-regulation or activation of SIRT1 in cardiovascular aging and age-related CVD may confer important application values.

Life-long caloric restriction does not alter the severity of age-related osteoarthritis

Chronic adipose tissue inflammation and its associated adipokines have been linked to the development of osteoarthritis (OA). It has been shown that caloric restriction may decrease body mass index and adiposity. The objectives of this study were to investigate the effect of lifelong caloric restriction on bone morphology, joint inflammation, and spontaneously occurring OA development in aged mice. C57BL/NIA mice were fed either a calorie-restricted (CR) or ad libitum (AL) diet starting at 14 weeks of age. All mice were sacrificed at 24 months of age. Adipose tissue and knee joints were then harvested. Bone parameters of the joints were analyzed by micro-CT. OA and joint synovitis were determined using histology and semiquantitative analysis. Lifelong caloric restriction did not alter the severity of OA development in C57BL/NIA aged mice, and there was no difference in the total joint Mankin score between CR and AL groups (p = 0.99). Mice also exhibited similar levels of synovitis (p = 0.54). The bone mineral density of the femur and the tibia was comparable between the groups with a small increase in cancellous bone volume fraction in the lateral femoral condyle of the CR group compared with the AL group. Lifelong caloric restriction did not alter the incidence of OA or joint synovitis in C57BL/NIA mice, indicating that a reduction of caloric intake alone was not sufficient to prevent spontaneous age-related OA. Nonetheless, early initiation of CR continued throughout a life span did not negatively impact bone structural properties.

RETRACTED: Akt2 knockout alleviates prolonged caloric restriction-induced change in cardiac contractile function through regulation of autophagy

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). At the request of the University of Wyoming, this article has been retracted. Although an investigation report from Air Force Medical University found no evidence of misconduct, the University of Wyoming’s institutional investigation of the work authored by Dr. Jun Ren found evidence of data irregularities in Figures 2, 3, and 4 that affect the reported results and conclusions. All authors have been notified of the retraction of this article.

Influence of a ketogenic diet, fish-oil, and calorie restriction on plasma metabolites and lipids in C57BL/6J mice

BACKGROUND

Diet therapies including calorie restriction, ketogenic diets, and fish-oil supplementation have been used to improve health and to treat a variety of neurological and non-neurological diseases.

METHODS

We investigated the effects of three diets on circulating plasma metabolites (glucose and β-hydroxybutyrate), hormones (insulin and adiponectin), and lipids over a 32-day period in C57BL/6J mice. The diets evaluated included a standard rodent diet (SD), a ketogenic diet (KD), and a standard rodent diet supplemented with fish-oil (FO). Each diet was administered in either unrestricted (UR) or restricted (R) amounts to reduce body weight by 20%.

RESULTS

The KD-UR increased body weight and glucose levels and promoted a hyperlipidemic profile, whereas the FO-UR decreased body weight and glucose levels and promoted a normolipidemic profile, compared to the SD-UR. When administered in restricted amounts, all three diets produced a similar plasma metabolite profile, which included decreased glucose levels and a normolipidemic profile. Linear regression analysis showed that circulating glucose most strongly predicted body weight and triglyceride levels, whereas calorie intake moderately predicted glucose levels and strongly predicted ketone body levels.

CONCLUSIONS

These results suggest that biomarkers of health can be improved when diets are consumed in restricted amounts, regardless of macronutrient composition.

Effects of diet on brain plasticity in animal and human studies: mind the gap

Dietary interventions have emerged as effective environmental inducers of brain plasticity. Among these dietary interventions, we here highlight the impact of caloric restriction (CR: a consistent reduction of total daily food intake), intermittent fasting (IF, every-other-day feeding), and diet supplementation with polyphenols and polyunsaturated fatty acids (PUFAs) on markers of brain plasticity in animal studies. Moreover, we also discuss epidemiological and intervention studies reporting the effects of CR, IF and dietary polyphenols and PUFAs on learning, memory, and mood. In particular, we evaluate the gap in mechanistic understanding between recent findings from animal studies and those human studies reporting that these dietary factors can benefit cognition, mood, and anxiety, aging, and Alzheimer's disease-with focus on the enhancement of structural and functional plasticity markers in the hippocampus, such as increased expression of neurotrophic factors, synaptic function and adult neurogenesis. Lastly, we discuss some of the obstacles to harnessing the promising effects of diet on brain plasticity in animal studies into effective recommendations and interventions to promote healthy brain function in humans. Together, these data reinforce the important translational concept that diet, a modifiable lifestyle factor, holds the ability to modulate brain health and function.

Intermittent fasting attenuates inflammasome activity in ischemic stroke

Recent findings have revealed a novel inflammatory mechanism that contributes to tissue injury in cerebral ischemia mediated by multi-protein complexes termed inflammasomes. Intermittent fasting (IF) can decrease the levels of pro-inflammatory cytokines in the periphery and brain. Here we investigated the impact of IF (16h of food deprivation daily) for 4months on NLRP1 and NLRP3 inflammasome activities following cerebral ischemia. Ischemic stroke was induced in C57BL/6J mice by middle cerebral artery occlusion, followed by reperfusion (I/R). IF decreased the activation of NF-κB and MAPK signaling pathways, the expression of NLRP1 and NLRP3 inflammasome proteins, and both IL-1β and IL-18 in the ischemic brain tissue. These findings demonstrate that IF can attenuate the inflammatory response and tissue damage following ischemic stroke by a mechanism involving suppression of NLRP1 and NLRP3 inflammasome activity.

Inhibition of AMPK accentuates prolonged caloric restriction-induced change in cardiac contractile function through disruption of compensatory autophagy

Prolonged caloric restriction often results in alteration in heart geometry and function although the underlying mechanism remains poorly defined. Autophagy, a conserved pathway for bulk degradation of intracellular proteins and organelles, preserves energy and nutrient in the face of caloric insufficiency. This study was designed to examine the role of AMPK in prolonged caloric restriction-induced change in cardiac homeostasis and the underlying mechanism(s) involved with a focus on autophagy. Wild-type (WT) and AMPK kinase dead (KD) mice were caloric restricted (by 40%) for 30 weeks. Echocardiographic, cardiomyocyte contractile and intracellular Ca²⁺ properties, autophagy and autophagy regulatory proteins were evaluated. Caloric restriction compromised echocardiographic indices (decreased ventricular mass, left ventricular diameters, and cardiac output), cardiomyocyte contractile and intracellular Ca²⁺ properties associated with upregulated autophagy (Beclin-1, Atg5 and LC3BII-to-LC3BI ratio), increased autophagy adaptor protein p62, elevated phosphorylation of AMPK and TSC1/2, depressed phosphorylation of mTOR and ULK1. Although AMPK inhibition did not affect cardiac mechanical function, autophagy and autophagy signaling proteins, it significantly accentuated caloric restriction-induced changes in myocardial contractile function and intracellular Ca²⁺ handling. Interestingly, AMPK inhibition reversed caloric restriction-induced changes in autophagy and autophagy signaling. AMPK inhibition led to dampened levels of Beclin-1, Atg 5 and LC3B ratio along with suppressed phosphorylation of AMPK and TSC1/2 as well as elevated phosphorylation of mTOR and ULK1. Taken together, these data suggest an indispensible role for AMPK in the maintenance of cardiac homeostasis under prolonged caloric restriction-induced pathological changes possibly through autophagy regulation. This article is part of a Special Issue entitled: Autophagy and protein quality control in cardiometabolic diseases.

Effects of interventions on adiponectin and adiponectin receptors

Adiponectin secreted from adipose tissue binds to two distinct adiponectin receptors (AdipoR1 and AdipoR2) identified and exerts its anti-diabetic effects in insulin-sensitive organs including liver, skeletal muscle and adipose tissue as well as amelioration of vascular dysfunction in the various vasculatures. A number of experimental and clinical observations have demonstrated that circulating levels of adiponectin are markedly reduced in obesity, type 2 diabetes, hypertension, and coronary artery disease. Therapeutic interventions which can improve the action of adiponectin including elevation of circulating adiponectin concentration or up-regulation and/or activation of its receptors, could provide better understanding of strategies to ameliorate metabolic disorders and vascular disease. The focus of the present review is to summarize accumulating evidence showing the role of interventions such as pharmacological agents, exercise, and calorie restriction in the expression of adiponectin and adiponectin receptors.

Benefits of caloric restriction for cardiometabolic health, including type 2 diabetes mellitus risk

In the United States, life expectancy has markedly increased during the past century, and population ageing is expected to double within the next 25 years. The process of ageing in a population is associated with the development of chronic diseases, such as type 2 diabetes mellitus, that can be prevented, and even reversed, with the implementation of healthy lifestyle interventions. The evidence to date, consolidated by the numerous epidemiological studies and clinical trials conducted, suggests that caloric restriction is an effective nutritional intervention for preventing most of these age-related conditions. At a metabolic level, caloric restriction with adequate nutrition has been shown to improve insulin sensitivity, reduce fasting glucose and insulin concentration and prevent obesity, type 2 diabetes, hypertension and chronic inflammation. The purpose of this article is to review current knowledge of the metabolic and clinical implications of caloric restriction with adequate nutrition for the prevention of type 2 diabetes and cardiovascular disease.

Effects of mild calorie restriction on anxiety and hypothalamic-pituitary-adrenal axis responses to stress in the male rat

Chronic calorie restriction (CR) is one of the few interventions to improve longevity and quality of life in a variety of species. It also reduces behavioral indices of anxiety and influences some stress hormones under basal conditions. However, it is not known how CR influences hypothalamic–pituitary–adrenal (HPA) axis function or if those on a CR diet have heightened HPA axis responses to stress. We hypothesized elevated basal glucocorticoid levels induced by CR would lead to exacerbated HPA axis responses to the psychological stress, restraint, in the male rat. We first confirmed rats fed 75% of their normal calorie intake for 3 weeks were less anxious than ad libitum‐fed (AD) rats in the elevated plus maze test for anxiety. The anxiolytic effect was mild, with only grooming significantly attenuated in the open field and no measured behavior affected in the light/dark box. Despite elevated basal glucocorticoids, CR rats had very similar hormonal and central responses to 15‐min restraint to the AD rats. Both CR and AD rats responded to restraint stress with a robust increase in glucocorticoids that was resolved by 60 min. Both groups also showed robust neuronal activation in the paraventricular nucleus of the hypothalamus and in other stress‐ and feeding‐sensitive brain regions that was not substantially affected by calorie intake. Our findings thus demonstrate chronic mild CR is subtly anxiolytic and is not likely to affect HPA axis responses to psychological stress. These findings support research suggesting a beneficial effect of mild CR.

Caloric restriction, caloric restriction mimetics, and healthy aging in Okinawa: controversies and clinical implications

PURPOSE OF REVIEW

To examine the role of two nutritional factors implicated in the healthy aging of the Okinawans: caloric restriction; and traditional foods with potential caloric restriction-mimetic properties.

RECENT FINDINGS

Caloric restriction is a research priority for the US National Institute on Aging. However, little is known regarding health effects in humans. Some caloric restriction-related outcomes, such as cause-specific mortality and lifespan, are not practical for human clinical trials. Therefore, epidemiological data on older Okinawans, who experienced a caloric restriction-like diet for close to half their lives, are of special interest. The nutritional data support mild caloric restriction (10-15%) and high consumption of foods that may mimic the biological effects of caloric restriction, including sweet potatoes, marine-based carotenoid-rich foods, and turmeric. Phenotypic evidence is consistent with caloric restriction (including short stature, low body weight, and lean BMI), less age-related chronic disease (including cardiovascular diseases, cancer, and dementia), and longer lifespan (mean and maximum).

SUMMARY

Both caloric restriction and traditional Okinawan functional foods with caloric restriction-mimetic properties likely had roles in the extended healthspan and lifespan of the Okinawans. More research is needed on health consequences of caloric restriction and foods with caloric restriction-mimetic properties to identify possible nutritional interventions for healthy aging.

The effects of caloric restriction against ethanol-induced oxidative and nitrosative cardiotoxicity and plasma lipids in rats

Caloric restriction (CR) prevents or delays a wide range of aging-related diseases possibly through alleviation of oxidative stress. The aim of our study was to examine the effect of CR on oxidative and nitrosative cardiac damage in rats, induced by acute ethanol intoxication. Male Wistar rats were divided into following groups: control; calorie-restricted groups with intake of 60-70% (CR60-70) and 40-50% of daily energy needs (CR40-50); ethanol-treated group (E); calorie-restricted, ethanol-treated groups (CR60-70 + E, CR40-50 + E). Ethanol was administered in five doses of 2 g/kg every 12 h, while the duration of CR was five weeks before ethanol treatment. Malondialdehyde level was significantly lower in CR60-70 + E and significantly higher in CR40-50 + E vs. control. Nitrite and nitrate level was significantly higher in CR40-50 + E compared to control group. Activity of total superoxide dismutase (SOD) and its isoenzyme, copper/zinc-SOD (Cu/ZnSOD), was significantly higher in CR60-70 + E and lower in CR40-50 + E vs. control. Activity of manganese-SOD (MnSOD), that is also SOD isoenzyme, was significantly lower in  CR40-50 + E compared to control group. Plasma content of sulfhydryl (SH) groups was significantly higher in CR60-70 group vs. control. Plasma concentration of total cholesterol, triacylglycerol, low-density lipoproteins and high-density lipoproteins was significantly lower in CR60-70 group compared to control values. Food restriction to 60-70% of daily energy needs has a protective effect on acute ethanol-induced oxidative and nitrosative cardiac damage, at least partly due to alleviation of ethanol-induced decrease in SOD activity, while restriction to 40-50% of energy needs aggravates lipid peroxidation and nitrosative stress.

Calorie restriction can reverse, as well as prevent, aging cardiomyopathy

Calorie restriction (CR) is the most widely studied intervention protecting from the adverse effects of aging. Almost all prior studies have examined the effects of CR initiated in young animals. Studies examining the effects of CR on development of aging cardiomyopathy found only partial prevention. The major goal of this study was to determine whether CR initiated after aging cardiomyopathy developed could reverse the cardiomyopathy. Aging cardiomyopathy in 2-year-old mice was characterized by reduced left ventricular (LV) function, cardiac hypertrophy, and increased cardiac apoptosis and fibrosis. When short-term (2 months) CR was initiated after aging cardiomyopathy developed in 20-month-old mice, the decrease in cardiac function, and increases in LV weight, myocardial fibrosis and apoptosis were reversed, such that the aging hearts in these mice were indistinguishable from those of young mice or mice where CR was initiated in young mice. If apoptosis was the mechanism for protecting against aging cardiomyopathy, then total myocyte numbers should have reverted to normal with CR, but did not. However, the alterations in cytoskeletal proteins, which contribute to aging cardiomyopathy, were no longer observed with CR. This is the first study to demonstrate complete prevention of aging cardiomyopathy by CR and, more importantly, that instituting this intervention even later in life can rapidly correct aging cardiomyopathy, which could have important therapeutic implications.

Resveratrol improves vascular function in patients with hypertension and dyslipidemia by modulating NO metabolism

Epidemiological studies have demonstrated that the Mediterranean diet, which is rich in resveratrol, is associated with a significantly reduced risk of cardiovascular disease. However, the molecular mechanisms that underlie the beneficial effects of resveratrol on cardiovascular function remain incompletely understood. Therefore, we set out to identify the molecular target(s) mediating the protective action of resveratrol on vascular function. To this end, we performed vascular reactivity studies to evaluate the effects of resveratrol on superior thyroid artery obtained from 59 patients with hypertension and dyslipidemia. We found that resveratrol evoked vasorelaxation and reduced endothelial dysfunction through the modulation of NO metabolism via (1) an 5' adenosine monophosphate-activated protein kinase-mediated increase in endothelial NO synthase activity; (2) a rise in tetrahydrobiopterin levels, which also increases endothelial NO synthase activity; and (3) attenuation of vascular oxidative stress, brought about by overexpression of manganese superoxide dismutase via an nuclear factor erythroid-derived 2-like 2-dependent mechanism. The effects of resveratrol on acetylcholine vasorelaxation were also tested in vessels from patients with nonhypertensive nondyslipidemia undergoing thyroid surgery. In this setting, resveratrol failed to exert any effect. Thus, our finding that resveratrol reduces endothelial dysfunction, an early pathophysiological feature and independent predictor of poor prognosis in most forms of cardiovascular disease, supports the concept that the risk of vascular events could be further reduced by adherence to a set of dietary and behavioral guidelines.

Metabolic adaptations to short-term every-other-day feeding in long-living Ames dwarf mice

Restrictive dietary interventions exert significant beneficial physiological effects in terms of aging and age-related disease in many species. Every other day feeding (EOD) has been utilized in aging research and shown to mimic many of the positive outcomes consequent with dietary restriction. This study employed long living Ames dwarf mice subjected to EOD feeding to examine the adaptations of the oxidative phosphorylation and antioxidative defense systems to this feeding regimen. Every other day feeding lowered liver glutathione (GSH) concentrations in dwarf and wild type (WT) mice but altered GSH biosynthesis and degradation in WT mice only. The activities of liver OXPHOS enzymes and corresponding proteins declined in WT mice fed EOD while in dwarf animals, the levels were maintained or increased with this feeding regimen. Antioxidative enzymes were differentially affected depending on the tissue, whether proliferative or post-mitotic. Gene expression of components of liver methionine metabolism remained elevated in dwarf mice when compared to WT mice as previously reported however, enzymes responsible for recycling homocysteine to methionine were elevated in both genotypes in response to EOD feeding. The data suggest that the differences in anabolic hormone levels likely affect the sensitivity of long living and control mice to this dietary regimen, with dwarf mice exhibiting fewer responses in comparison to WT mice. These results provide further evidence that dwarf mice may be better protected against metabolic and environmental perturbations which may in turn, contribute to their extended longevity.

Role of mitochondrial dysfunction and altered autophagy in cardiovascular aging and disease: from mechanisms to therapeutics

Advanced age is associated with a disproportionate prevalence of cardiovascular disease (CVD). Intrinsic alterations in the heart and the vasculature occurring over the life course render the cardiovascular system more vulnerable to various stressors in late life, ultimately favoring the development of CVD. Several lines of evidence indicate mitochondrial dysfunction as a major contributor to cardiovascular senescence. Besides being less bioenergetically efficient, damaged mitochondria also produce increased amounts of reactive oxygen species, with detrimental structural and functional consequences for the cardiovascular system. The age-related accumulation of dysfunctional mitochondrial likely results from the combination of impaired clearance of damaged organelles by autophagy and inadequate replenishment of the cellular mitochondrial pool by mitochondriogenesis. In this review, we summarize the current knowledge about relevant mechanisms and consequences of age-related mitochondrial decay and alterations in mitochondrial quality control in the cardiovascular system. The involvement of mitochondrial dysfunction in the pathogenesis of cardiovascular conditions especially prevalent in late life and the emerging connections with neurodegeneration are also illustrated. Special emphasis is placed on recent discoveries on the role played by alterations in mitochondrial dynamics (fusion and fission), mitophagy, and their interconnections in the context of age-related CVD and endothelial dysfunction. Finally, we discuss pharmacological interventions targeting mitochondrial dysfunction to delay cardiovascular aging and manage CVD.

Endothelial aging associated with oxidative stress can be modulated by a healthy mediterranean diet

Aging is a condition which favors the development of atherosclerosis, which has been associated with a breakdown in repair processes that occurs in response to cell damage. The dysregulation of the biological systems associated with aging are produced partly through damage which accumulates over time. One major source of this injury is oxidative stress, which can impair biological structures and the mechanisms by which they are repaired. These mechanisms are based on the pathogenesis of endothelial dysfunction, which in turn is associated with cardiovascular disease, carcinogenesis and aging. The dependent dysfunction of aging has been correlated with a reduction in the number and/or functional activity of endothelial progenitor cells, which could hinder the repair and regeneration of the endothelium. In addition, aging, inflammation and oxidative stress are endogenous factors that cause telomere shortening, which is dependent on oxidative cell damage. Moreover, telomere length correlates with lifestyle and the consumption of a healthy diet. Thus, diseases associated with aging and age may be caused by the long-term effects of oxidative damage, which are modified by genetic and environmental factors. Considering that diet is a very important source of antioxidants, in this review we will analyze the relationship between oxidative stress, aging, and the mechanisms which may be involved in a higher survival rate and a lower incidence of the diseases associated with aging in populations which follow a healthy diet.

Role of the hypothalamus in mediating protective effects of dietary restriction during aging

Dietary restriction (DR) can extend lifespan and reduce disease burden across a wide range of animals and yeast but the mechanisms mediating these remarkably protective effects remain to be elucidated despite extensive efforts. Although it has generally been assumed that protective effects of DR are cell-autonomous, there is considerable evidence that many whole-body responses to nutritional state, including DR, are regulated by nutrient-sensing neurons. In this review, we explore the hypothesis that nutrient sensing neurons in the ventromedial hypothalamus hierarchically regulate the protective responses of dietary restriction. We describe multiple peripheral responses that are hierarchically regulated by the hypothalamus and we present evidence for non-cell autonomous signaling of dietary restriction gathered from a diverse range of models including invertebrates, mammalian cell culture, and rodent studies.

Longevity and aging

Research into the biology of aging seeks to understand the basic mechanisms of aging, with the goal of extending the period of life spent free from chronic disease and disability. Aging results from molecular processes that are modulated by genetic and environmental parameters. At least some of these mechanisms of aging are broadly shared across eukaryotic species from yeast to mice, and likely humans, as well. Recent breakthroughs in aging-related research have identified conserved longevity factors, such as components of the insulin-like signaling pathway and the mechanistic target of rapamycin, and have suggested potential paths toward developing the first interventions to slow aging in humans.

Beneficial cardiac effects of caloric restriction are lost with age in a murine model of obesity

Obesity is associated with increased diastolic stiffness and myocardial steatosis and dysfunction. The impact of aging on the protective effects of caloric restriction (CR) is not clear. We studied 2-month (younger) and 6-7-month (older)-old ob/ob mice and age-matched C57BL/6J controls (WT). Ob/ob mice were assigned to diet ad libitum or CR for 4 weeks. We performed echocardiograms, myocardial triglyceride assays, Oil Red O staining, and measured free fatty acids, superoxide, NOS activity, ceramide levels, and Western blots. In younger mice, CR restored diastolic function, reversed myocardial steatosis, and upregulated Akt phosphorylation. None of these changes was observed in the older mice; however, CR decreased oxidative stress and normalized NOS activity in these animals. Interestingly, myocardial steatosis was not associated with increased ceramide, but CR altered the composition of ceramides. In this model of obesity, aging attenuates the benefits of CR on myocardial structure and function.

Xenohormetic and anti-aging activity of secoiridoid polyphenols present in extra virgin olive oil: a new family of gerosuppressant agents

Aging can be viewed as a quasi-programmed phenomenon driven by the overactivation of the nutrient-sensing mTOR gerogene. mTOR-driven aging can be triggered or accelerated by a decline or loss of responsiveness to activation of the energy-sensing protein AMPK, a critical gerosuppressor of mTOR. The occurrence of age-related diseases, therefore, reflects the synergistic interaction between our evolutionary path to sedentarism, which chronically increases a number of mTOR activating gero-promoters (e.g., food, growth factors, cytokines and insulin) and the "defective design" of central metabolic integrators such as mTOR and AMPK. Our laboratories at the Bioactive Food Component Platform in Spain have initiated a systematic approach to molecularly elucidate and clinically explore whether the "xenohormesis hypothesis," which states that stress-induced synthesis of plant polyphenols and many other phytochemicals provides an environmental chemical signature that upregulates stress-resistance pathways in plant consumers, can be explained in terms of the reactivity of the AMPK/mTOR-axis to so-called xenohormetins. Here, we explore the AMPK/mTOR-xenohormetic nature of complex polyphenols naturally present in extra virgin olive oil (EVOO), a pivotal component of the Mediterranean style diet that has been repeatedly associated with a reduction in age-related morbid conditions and longer life expectancy. Using crude EVOO phenolic extracts highly enriched in the secoiridoids oleuropein aglycon and decarboxymethyl oleuropein aglycon, we show for the first time that (1) the anticancer activity of EVOO secoiridoids is related to the activation of anti-aging/cellular stress-like gene signatures, including endoplasmic reticulum (ER) stress and the unfolded protein response, spermidine and polyamine metabolism, sirtuin-1 (SIRT1) and NRF2 signaling; (2) EVOO secoiridoids activate AMPK and suppress crucial genes involved in the Warburg effect and the self-renewal capacity of "immortal" cancer stem cells; (3) EVOO secoiridoids prevent age-related changes in the cell size, morphological heterogeneity, arrayed cell arrangement and senescence-associated β-galactosidase staining of normal diploid human fibroblasts at the end of their proliferative lifespans. EVOO secoiridoids, which provide an effective defense against plant attack by herbivores and pathogens, are bona fide xenohormetins that are able to activate the gerosuppressor AMPK and trigger numerous resveratrol-like anti-aging transcriptomic signatures. As such, EVOO secoiridoids constitute a new family of plant-produced gerosuppressant agents that molecularly "repair" the aimless (and harmful) AMPK/mTOR-driven quasi-program that leads to aging and aging-related diseases, including cancer.

From sirtuin biology to human diseases: an update

Originally rising to notoriety for their role in the regulation of aging, sirtuins are a family of NAD(+)-dependent enzymes that have been connected to a steadily growing set of biological processes. In addition to regulating aging, sirtuins play key roles in the maintenance of organismal metabolic homeostasis. These enzymes also have primarily protective functions in the development of many age-related diseases, including cancer, neurodegeneration, and cardiovascular disease. In this minireview, we provide an update on the known roles for each of the seven mammalian sirtuins in these areas.

Energy intake and exercise as determinants of brain health and vulnerability to injury and disease

Evolution favored individuals with superior cognitive and physical abilities under conditions of limited food sources, and brain function can therefore be optimized by intermittent dietary energy restriction (ER) and exercise. Such energetic challenges engage adaptive cellular stress-response signaling pathways in neurons involving neurotrophic factors, protein chaperones, DNA-repair proteins, autophagy, and mitochondrial biogenesis. By suppressing adaptive cellular stress responses, overeating and a sedentary lifestyle may increase the risk of Alzheimer's and Parkinson's diseases, stroke, and depression. Intense concerted efforts of governments, families, schools, and physicians will be required to successfully implement brain-healthy lifestyles that incorporate ER and exercise.

The sirtuin SIRT6 blocks IGF-Akt signaling and development of cardiac hypertrophy by targeting c-Jun

Abnormal activation of insulin-like growth factor (IGF)-Akt signaling is implicated in the development of various diseases, including heart failure. However, the molecular mechanisms that regulate activation of this signaling pathway are not completely understood. Here we show that sirtuin 6 (SIRT6), a nuclear histone deacetylase, functions at the level of chromatin to directly attenuate IGF-Akt signaling. SIRT6-deficient mice developed cardiac hypertrophy and heart failure, whereas SIRT6 transgenic mice were protected from hypertrophic stimuli, indicating that SIRT6 acts as a negative regulator of cardiac hypertrophy. SIRT6-deficient mouse hearts showed hyperactivation of IGF signaling-related genes and their downstream targets. Mechanistically, SIRT6 binds to and suppresses the promoter of IGF signaling-related genes by interacting with c-Jun and deacetylating histone 3 at Lys9 (H3K9). We also found reduced SIRT6 expression in human failing hearts. These findings disclose a new link between SIRT6 and IGF-Akt signaling and implicate SIRT6 in the development of cardiac hypertrophy and failure.

Metabolic and neuropsychiatric effects of calorie restriction and sirtuins

Most living organisms, including humans, age. Over time the ability to do physical and intellectual work deteriorates, and susceptibility to infectious, metabolic, and neurodegenerative diseases increases, which leads to general fitness decline and ultimately to death. Work in model organisms has demonstrated that genetic and environmental manipulations can prevent numerous age-associated diseases, improve health at advanced age, and increase life span. Calorie restriction (CR) (consumption of a diet with fewer calories but containing all the essential nutrients) is the most robust manipulation, genetic or environmental, to extend longevity and improve health parameters in laboratory animals. However, outside of the protected laboratory environment, the effects of CR are much less certain. Understanding the molecular mechanisms of CR may lead to the development of novel therapies to combat diseases of aging and to improve the quality of life. Sirtuins, a family of NAD(+)-dependent enzymes, mediate a number of metabolic and behavioral responses to CR and are intriguing targets for pharmaceutical interventions. We review the molecular understanding of CR; the role of sirtuins in CR; and the effects of sirtuins on physiology, mood, and behavior.

The intersection between aging and cardiovascular disease

The average lifespan of humans is increasing, and with it the percentage of people entering the 65 and older age group is growing rapidly and will continue to do so in the next 20 years. Within this age group, cardiovascular disease will remain the leading cause of death, and the cost associated with treatment will continue to increase. Aging is an inevitable part of life and unfortunately poses the largest risk factor for cardiovascular disease. Although numerous studies in the cardiovascular field have considered both young and aged humans, there are still many unanswered questions as to how the genetic pathways that regulate aging in model organisms influence cardiovascular aging. Likewise, in the molecular biology of aging field, few studies fully assess the role of these aging pathways in cardiovascular health. Fortunately, this gap is beginning to close, and these two fields are merging together. We provide an overview of some of the key genes involved in regulating lifespan and health span, including sirtuins, AMP-activated protein kinase, mammalian target of rapamycin, and insulin-like growth factor 1 and their roles regulating cardiovascular health. We then discuss a series of review articles that will appear in succession and provide a more comprehensive analysis of studies carried out linking genes of aging and cardiovascular health, and perspectives of future directions of these two intimately linked fields.

Mechanisms involved in the aging-induced vascular dysfunction

Vascular aging is a key process determining health status of aged population. Aging is an independent cardiovascular risk factor associated to an impairment of endothelial function, which is a very early and important event leading to cardiovascular disease. Vascular aging, formerly being considered an immutable and inexorable risk factor, is now viewed as a target process for intervention in order to achieve a healthier old age. A further knowledge of the mechanisms underlying the age-related vascular dysfunction is required to design an adequate therapeutic strategy to prevent or restore this impairment of vascular functionality. Among the proposed mechanisms that contribute to age-dependent endothelial dysfunction, this review is focused on the following aspects occurring into the vascular wall: (1) the reduction of nitric oxide (NO) bioavailability, caused by diminished NO synthesis and/or by augmented NO scavenging due to oxidative stress, leading to peroxynitrite formation (ONOO(-)); (2) the possible sources involved in the enhancement of oxidative stress; (3) the increased activity of vasoconstrictor factors; and (4) the development of a low-grade pro-inflammatory environment. Synergisms and interactions between all these pathways are also analyzed. Finally, a brief summary of some cellular mechanisms related to endothelial cell senescence (including telomere and telomerase, stress-induced senescence, as well as sirtuins) are implemented, as they are likely involved in the age-dependent endothelial dysfunction, as well as in the lower vascular repairing capacity observed in the elderly. Prevention or reversion of those mechanisms leading to endothelial dysfunction through life style modifications or pharmacological interventions could markedly improve cardiovascular health in older people.

Cardiomyocyte death: mechanisms and translational implications

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality worldwide. Although treatments have improved, development of novel therapies for patients with CVD remains a major research goal. Apoptosis, necrosis, and autophagy occur in cardiac myocytes, and both gradual and acute cell death are hallmarks of cardiac pathology, including heart failure, myocardial infarction, and ischemia/reperfusion. Pharmacological and genetic inhibition of autophagy, apoptosis, or necrosis diminishes infarct size and improves cardiac function in these disorders. Here, we review recent progress in the fields of autophagy, apoptosis, and necrosis. In addition, we highlight the involvement of these mechanisms in cardiac pathology and discuss potential translational implications.

Improved insulin sensitivity with calorie restriction does not require reduced JNK1/2, p38, or ERK1/2 phosphorylation in skeletal muscle of 9-month-old rats

Calorie restriction [CR; ∼40% below ad libitum (AL) intake] improves the health of many species, including rats, by mechanisms that may be partly related to enhanced insulin sensitivity for glucose disposal by skeletal muscle. Excessive activation of several mitogen-activated protein kinases (MAPKs), including JNK1/2, p38, and ERK1/2 has been linked to insulin resistance. Although insulin can activate ERK1/2, this effect is not required for insulin-mediated glucose uptake. We hypothesized that skeletal muscle from male 9-mo-old Fischer 344/Brown Norway rats CR (35-40% beginning at 3 mo old) versus AL rats would have 1) attenuated activation of JNK1/2, p38, and ERK1/2 under basal conditions; and 2) no difference for insulin-induced ERK1/2 activation. In contrast to our hypothesis, there were significant CR-related increases in the phosphorylation of p38 (epitrochlearis, soleus, and gastrocnemius), JNK1 (epitrochlearis and soleus), and JNK2 (gastrocnemius). Consistent with our hypothesis, CR did not alter insulin-mediated ERK1/2 activation. The greater JNK1/2 and p38 phosphorylation with CR was not attributable to diet effects on muscle oxidative stress (assessed by protein carbonyls and 4-hydroxynonenal protein conjugates). In muscles from the same rats used for the present study, we previously reported a CR-related increase in insulin-mediated glucose uptake by the epitrochlearis and the soleus (Sharma N, Arias EB, Bhat AD, Sequea DA, Ho S, Croff KK, Sajan MP, Farese RV, Cartee GD. Am J Physiol Endocrinol Metab 300: E966-E978, 2011). The present results indicate that the improved insulin sensitivity with CR is not attributable to attenuated MAPK phosphorylation in skeletal muscle.