Temporal linkage between the phenotypic and genomic responses to caloric restriction

Extended lifespan in female Drosophila melanogaster through late-life calorie restriction

Calorie restriction has many beneficial effects on healthspan and lifespan in a variety of species. However, how late in life application of caloric restriction can extend fly life is not clear. Here we show that late-life calorie restriction increases lifespan in female Drosophila melanogaster aged on a high-calorie diet. This shift results in rapid decrease in mortality rate and extends fly lifespan. In contrast, shifting female flies from a low- to a high-calorie diet leads to a rapid increase in mortality and shorter lifespan. These changes are mediated by immediate metabolic and physiological adaptations. One of such adaptation is rapid adjustment in egg production, with flies directing excess energy towards egg production when shifted to a high diet, or away from reproduction in females shifted to low-caloric diet. However, lifelong female fecundity reveals no associated fitness cost due to CR when flies are shifted to a high-calorie diet. In view of high conservation of the beneficial effects of CR on physiology and lifespan in a wide variety of organisms, including humans, our findings could provide valuable insight into CR applications that could provide health benefits later in life.

Late-life shift in caloric intake affects fly metabolism and longevity

The prevalence of obesity is increasing in older adults and contributes to age-related decline. Caloric restriction (CR) alleviates obesity phenotypes and delays the onset of age-related changes. However, how late in life organisms benefit from switching from a high-(H) to a low-calorie (L) diet is unclear. We transferred male flies from a H to a L (HL) diet or vice versa (LH) at different times during life. Both shifts immediately change fly rate of aging even when applied late in life. HL shift rapidly reduces fly mortality rate to briefly lower rate than in flies on a constant L diet, and extends lifespan. Transcriptomic analysis uncovers that flies aged on H diet have acquired increased stress response, which may have temporal advantage over flies aged on L diet and leads to rapid decrease in mortality rate after HL switch. Conversely, a LH shift increases mortality rate, which is temporarily higher than in flies aged on a H diet, and shortens lifespan. Unexpectedly, more abundant transcriptomic changes accompanied LH shift, including increase in ribosome biogenesis, stress response and growth. These changes reflect protection from sudden release of ROS, energy storage, and use of energy to growth, which all likely contribute to higher mortality rate. As the beneficial effects of CR on physiology and lifespan are conserved across many organisms, our study provides framework to study underlying mechanisms of CR interventions that counteract the detrimental effects of H diets and reduce rate of aging even when initiated later in life.

Caloric Restriction Mitigates Kidney Fibrosis in an Aged and Obese Rat Model

Caloric restriction is an effective intervention to protract healthspan and lifespan in several animal models from yeast to primates, including humans. Caloric restriction has been found to induce cardiometabolic adaptations associated with improved health and to delay the onset and progression of kidney disease in different species, particularly in rodent models. In both aging and obesity, fibrosis is a hallmark of kidney disease, and epithelial-mesenchymal transition is a key process that leads to fibrosis and renal dysfunction during aging. In this study, we used an aged and obese rat model to evaluate the effect of long-term (6 months) caloric restriction (-40%) on renal damage both from a structural and functional point of view. Renal interstitial fibrosis was analyzed by histological techniques, whereas effects on mesenchymal (N-cadherin, Vimentin, Desmin and α-SMA), antioxidant (SOD1, SOD2, Catalase and GSTP1) inflammatory (YM1 and iNOS) markers and apoptotic/cell cycle (BAX, BCL2, pJNK, Caspase 3 and p27) pathways were investigated using Western blot analysis. Our results clearly showed that caloric restriction promotes cell cycle division and reduces apoptotic injury and fibrosis phenotype through inflammation attenuation and leukocyte infiltration. In conclusion, we highlight the beneficial effects of caloric restriction to preserve elderly kidney function.

Secreted MUP1 that reduced under ER stress attenuates ER stress induced insulin resistance through suppressing protein synthesis in hepatocytes

Disturbed endoplasmic reticulum (ER) stress response driven by the excessive lipid accumulation in the liver is a characteristic feature in the pathogenesis of non-alcoholic fatty liver disease (NAFLD). Restoring metabolic homeostasis by targeting ER stress is a potentially therapeutic strategy for NAFLD. Here we aim to identify novel proteins or pathways involved in regulating ER stress response and therapeutic targets for alleviating NAFLD. Proteomic and transcriptomic analysis demonstrated that major urinary proteins (MUPs) were significantly reduced in the livers from NAFLD mouse models. Then we confirmed that MUP1, the major secreted form of MUPs, was reduced at mRNA and protein expression levels in hepatocytes both in vivo and in vitro under ER stress. We further illustrated that MUP1 protein levels in the urine were reduced in mice with NAFLD, which was reversed by GLP-1 receptor agonist treatment. To study the relationship between ER stress and MUP1 biology, our analysis demonstrated that MUP1 was misfolded and trapped in the ER under ER stress in vivo. Interestingly, we discovered that recombinant MUP1 treatment in hepatocytes increased calcium efflux from the ER, which resulted in transient ER stress response, including reduced protein synthesis. These responses facilitated the alleviation of chemical induced ER stress in hepatocytes, which was suggested as "pre-adaptive ER stress". Besides, recombinant MUP1 pretreatment also improved ER stress-induced insulin resistance in hepatocytes. Our findings revealed a novel and critical role of MUP1, and recombinant MUP1 or its potential derivates may serve as a promising therapeutic target for alleviating NAFLD.

Why Gilgamesh failed: the mechanistic basis of the limits to human lifespan

The purpose of this Perspective is to clarify for an interdisciplinary audience the fundamental concepts of human longevity and provide evidence for a limit to human lifespan. This observed limit is placed into a broader framework by showing how it has arisen through the process of evolution and by enumerating the molecular mechanisms that may enforce it. Finally, we look toward potential future developments and the prospects for possibly circumventing the current limit.

The major urinary protein gene cluster knockout mouse as a novel model for translational metabolism research

Scientific evidence suggests that not only murine scent communication is regulated by major urinary proteins, but that their expression may also vary in response to metabolism via a yet unknown mechanism. Major urinary proteins are expressed mainly in the liver, showing a sexually dimorphic pattern with substantially higher expression in males. Here, we investigate the metabolic implications of a major urinary protein knockout in twelve-week-old male and female C57BL/6N mice during ad libitum feeding. Despite both sexes of major urinary protein knockout mice displayed numerically increased body weight and visceral adipose tissue proportions compared to sex-matched wildtype mice, the main genotype-specific metabolic differences were observed exclusively in males. Male major urinary protein knockout mice exhibited plasma and hepatic lipid accumulation accompanied by a hepatic transcriptome indicating an activation of lipogenesis. These findings match the higher major urinary protein expression in male compared to female wildtype mice, suggesting a more distinct reduction in energy requirements in male compared to female major urinary protein knockout mice. The observed sex-specific anabolic phenotype confirms a role of major urinary protein in metabolism and, since major urinary proteins are not expressed in humans, suggests the major urinary protein knockout mouse as a potential alternative model for translational metabolism research which needs to be further elucidated.

The Impact of Varying Food Availability on Gene Expression in the Liver: Testing the Match-Mismatch Hypothesis

Background

During early phases of life, such as prenatal or early postnatal development and adolescence, an organism's phenotype can be shaped by the environmental conditions it experiences. According to the Match-Mismatch hypothesis (MMH), changes to this environment during later life stages can result in a mismatch between the individual's adaptations and the prevailing environmental conditions. Thus, negative consequences in welfare and health can occur. We aimed to test the MMH in the context of food availability, assuming adolescence as a sensitive period of adaptation.

Methods

We have previously reported a study of the physiological and behavioral effects of match and mismatch conditions of high (ad libitum) and low (90% of ad libitum intake) food availability from adolescence to early adulthood in female C57BL/6J mice (n = 62). Here, we performed RNA-sequencing of the livers of a subset of these animals (n = 16) to test the effects of match and mismatch feeding conditions on the liver transcriptome.

Results

In general, we found no effect of the match-mismatch situations. Contrarily, the amount of food available during early adulthood (low vs. high) drove the differences we observed in final body weight and gene expression in the liver, regardless of the amount of food available to the animals during adolescence. Many of the differentially expressed genes and the corresponding biological processes found to be overrepresented overlapped, implicating common changes in various domains. These included metabolism, homeostasis, cellular responses to diverse stimuli, transport of bile acids and other molecules, cell differentiation, major urinary proteins, and immunity and inflammation.

Conclusions

Our previous and present observations found no support for the MMH in the context of low vs high food availability from adolescence to early adulthood in female C57BL/6J mice. However, even small differences of approximately 10% in food availability during early adulthood resulted in physiological and molecular changes with potential beneficial implications for metabolic diseases.

Myeloid FoxO1 depletion attenuates hepatic inflammation and prevents nonalcoholic steatohepatitis

Hepatic inflammation is culpable for the evolution of asymptomatic steatosis to nonalcoholic steatohepatitis (NASH). Hepatic inflammation results from abnormal macrophage activation. We found that FoxO1 links overnutrition to hepatic inflammation by regulating macrophage polarization and activation. FoxO1 was upregulated in hepatic macrophages, correlating with hepatic inflammation, steatosis and fibrosis in mice and patients with NASH. Myeloid cell-conditional FoxO1 knockout skewed macrophage polarization from pro-inflammatory M1 to anti-inflammatory M2 phenotypes, accompanied by the reduction of macrophage infiltration in liver. These effects mitigated overnutrition-induced hepatic inflammation and insulin resistance, contributing to improved hepatic metabolism and increased energy expenditure in myeloid cell FoxO1 knockout mice on HFD. When fed a NASH-inducing diet, myeloid cell FoxO1 knockout mice were protected from developing NASH, culminating in the reduction of hepatic inflammation, steatosis and fibrosis. Mechanistically, FoxO1 counteracts Stat6 to skew macrophage polarization from M2 toward M1 signatures to perpetuate hepatic inflammation in NASH. FoxO1 appears as a pivotal mediator of macrophage activation in response to overnutrition and a therapeutic target for ameliorating hepatic inflammation to stem the disease progression from benign steatosis to NASH.

Intermittent fasting and caloric restriction interact with genetics to shape physiological health in mice

Dietary interventions can dramatically affect physiological health and organismal lifespan. The degree to which organismal health is improved depends upon genotype and the severity of dietary intervention, but neither the effects of these factors, nor their interaction, have been quantified in an outbred population. Moreover, it is not well understood what physiological changes occur shortly after dietary change and how these may affect the health of an adult population. In this article, we investigated the effect of 6-month exposure of either caloric restriction (CR) or intermittent fasting (IF) on a broad range of physiological traits in 960 1-year old Diversity Outbred mice. We found CR and IF affected distinct aspects of physiology and neither the magnitude nor the direction (beneficial or detrimental) of effects were concordant with the severity of the intervention. In addition to the effects of diet, genetic variation significantly affected 31 of 36 traits (heritabilities ranged from 0.04 to 0.65). We observed significant covariation between many traits that was due to both diet and genetics and quantified these effects with phenotypic and genetic correlations. We genetically mapped 16 diet-independent and 2 diet-dependent significant quantitative trait loci, both of which were associated with cardiac physiology. Collectively, these results demonstrate the degree to which diet and genetics interact to shape the physiological health of adult mice following 6 months of dietary intervention.

A review of effects of calorie restriction and fasting with potential relevance to depression

In recent years, there has been a great deal of interest in the effects of calorie reduction (calorie restriction) and fasting on depression. In the current paper, we have reviewed the literature in this area, with discussion of the possible neurobiological mechanisms involved in calorie restriction and intermittent fasting. Factors which may play a role in the effects of these dietary manipulations on health include changes involving free fatty acids, ketone bodies, neurotransmitters, cyclic adenosine monophosphate response element binding protein (CREB), brain-derived neurotrophic factor (BDNF), cytokines, orexin, ghrelin, leptin, reactive oxygen species and autophagy. Several of these factors are potential contributors to improving symptoms of depression. Challenges encountered in research on calorie restriction and intermittent fasting are also discussed. Although much is now known about the acute effects of calorie restriction and intermittent fasting, further long term clinical studies are warranted.

Short-term protein restriction at advanced age stimulates FGF21 signalling, energy expenditure and browning of white adipose tissue

Dietary protein restriction has been demonstrated to improve metabolic health under various conditions. However, the relevance of ageing and age-related decline in metabolic flexibility on the effects of dietary protein restriction has not been addressed. Therefore, we investigated the effect of short-term dietary protein restriction on metabolic health in young and aged mice. Young adult (3 months old) and aged (18 months old) C57Bl/6J mice were subjected to a 3-month dietary protein restriction. Outcome parameters included fibroblast growth factor 21 (FGF21) levels, muscle strength, glucose tolerance, energy expenditure (EE) and transcriptomics of brown and white adipose tissue (WAT). Here, we report that a low-protein diet had beneficial effects in aged mice by reducing some aspects of age-related metabolic decline. These effects were characterized by increased plasma levels of FGF21, browning of subcutaneous WAT, increased body temperature and EE, while no changes were observed in glucose homeostasis and insulin sensitivity. Moreover, the low-protein diet used in this study was well-tolerated in aged mice indicated by the absence of adverse effects on body weight, locomotor activity and muscle performance. In conclusion, our study demonstrates that a short-term reduction in dietary protein intake can impact age-related metabolic health alongside increased FGF21 signalling, without negatively affecting muscle function. These findings highlight the potential of protein restriction as a strategy to induce EE and browning of WAT in aged individuals.

Preconditioning with Short-term Dietary Restriction Attenuates Cardiac Oxidative Stress and Hypertrophy Induced by Chronic Pressure Overload

Left ventricular (LV) hypertrophy and associated heart failure are becoming a more prevalent and critical public health issue with the aging of society, and are exacerbated by reactive oxygen species (ROS). Dietary restriction (DR) markedly inhibits senescent changes; however, prolonged DR is difficult. We herein investigated whether preconditioning with short-term DR attenuates chronic pressure overload-induced cardiac hypertrophy and associated oxidative stress. Male c57BL6 mice were randomly divided into an ad libitum (AL) diet or 40% restricted diet (DR preconditioning, DRPC) group for 2 weeks prior to ascending aortic constriction (AAC), and all mice were fed ad libitum after AAC surgery. Two weeks after surgery, pressure overload by AAC increased LV wall thickness in association with LV diastolic dysfunction and promoted myocyte hypertrophy and cardiac fibrosis in the AL+AAC group. Oxidative stress in cardiac tissue and mitochondria also increased in the AL+AAC group in association with increments in cardiac NADPH oxidase-derived and mitochondrial ROS production. LV hypertrophy and associated cardiac dysfunction and oxidative stress were significantly attenuated in the DRPC+AAC group. Moreover, less severe mitochondrial oxidative damage in the DRPC+AAC group was associated with the suppression of mitochondrial permeability transition and cardiac apoptosis. These results indicate that chronic pressure overload-induced cardiac hypertrophy in association with cardiac and mitochondrial oxidative damage were attenuated by preconditioning with short-term DR.

Healthful aging mediated by inhibition of oxidative stress

The progressive increase in lifespan over the past century carries with it some adversity related to the accompanying burden of debilitating diseases prevalent in the older population. This review focuses on oxidative stress as a major mechanism limiting longevity in general, and healthful aging, in particular. Accordingly, the first goal of this review is to discuss the role of oxidative stress in limiting longevity, and compare healthful aging and its mechanisms in different longevity models. Secondly, we discuss common signaling pathways involved in protection against oxidative stress in aging and in the associated diseases of aging, e.g., neurological, cardiovascular and metabolic diseases, and cancer. Much of the literature has focused on murine models of longevity, which will be discussed first, followed by a comparison with human models of longevity and their relationship to oxidative stress protection. Finally, we discuss the extent to which the different longevity models exhibit the healthful aging features through physiological protective mechanisms related to exercise tolerance and increased β-adrenergic signaling and also protection against diabetes and other metabolic diseases, obesity, cancer, neurological diseases, aging-induced cardiomyopathy, cardiac stress and osteoporosis.

Resemblance and differences in dietary restriction nephroprotective mechanisms in young and old rats

Dietary restriction (DR) is the strategy ameliorating the morbidity of various pathologies, including age-associated diseases. Acute kidney injury (AKI) remains a problem for the elderly with DR being a promising approach for diminishing its consequences. We evaluated the possible nephroprotective potential of short-term DR in young and old rats. DR in young rats resulted in pronounced beneficial effects normalizing lipid metabolism (triglycerides concentration, adiponectin level) activating autophagic-lysosomal system evaluated by LC3II/LC3I ratio, LAMP1, p62/SQSTM1 levels, and LysoTracker Green staining. DR had a remarkable recovering effect on mitochondrial structure and functions including regaining of mitochondrial membrane potential, the elevation of SIRT-3, PGC-1α, _Bcl-XL levels and partial restoration of ultrastructure. The beneficial effects of DR resulted in the mitigation of oxidative stress including a decrease in levels of protein carbonylation and lipid peroxidation. Aging led to decreased activity of autophagy, elevated oxidative stress and impaired kidney regenerative capacity. Eventually, in old rats, even 8-week DR was not able to ameliorate AKI, but it caused some rejuvenating effects including elevation of mitochondrial membrane potential and Bcl-X_L levels, as well as lowered severity of the oxidative stress. Thus, the age-associated decline of protective signaling demands extended DR to achieve nephroprotective potential in old animals.

Mechanisms and Effects of Dietary Restriction on CNS and Affective Disorders

Neuropsychiatric disorders, including depression contribute significantly to global disability and possess high social and health burden. Management is dominated by pharmacotherapy and psychotherapy; nevertheless, such treatments prevent or treat less than half of the patients, suggesting that alternative approaches are required. Emerging data suggest that diet may be an adjustable risk factor for psychiatric disorders. Caloric restriction (CR) possesses protective effects in almost all organs including the brain. However, the precise molecular pathways of these effects remain uncertain. In this review, we will discuss the putative neurobiological mechanisms of CR on the brain. The article will address also the molecular basis of the antidepressant effects of CR, primarily including ghrelin signaling, CREB neurotropic effects and ketone bodies production. Then we will highlight the probable effect of CR on the neuroinflammation, which emerges as a key pathogenetic factor for the majority of neuropsychiatric disorders. Finally, we discuss the so called caloric restriction mimetics, compounds that reproduce properties of CR. Further research will be required to verify the safety and efficacy of CR before a general approval can be proposed to introduce it and its mimetics in clinical practice for the treatment of neuropsychiatric disorders.

In Contrast to Dietary Restriction, Application of Resveratrol in Mice Does not Alter Mouse Major Urinary Protein Expression

Resveratrol (RSV) supplementation in mice has been discussed as partly mimicking the beneficial effects of dietary restriction (DR). However, data on putative benefits from resveratrol application in mice and other model organisms including humans is contradictory. Mouse major urinary proteins (MUPs) are a family of proteins that are expressed in rodent liver and secreted via urine. Impacting (mating) behavior and pheromone communication, they are severely down-regulated upon DR. We carried out two studies in C57BL/6Rj mice where RSV was either supplemented via diet or injected intraperitoneally for 8 weeks. Contrary to −40% DR, RSV did not decrease total MUP protein expression or Mup (amongst others Mup3, Mup5, Mup6, Mup15, and Mup20) mRNA levels in mouse liver when compared to ad-libitum (AL)-fed controls. Since inhibitory glucocorticoid response elements can be found in Mup promoters, we also measured glucocorticoid receptor (GR) levels in nuclear hepatic extracts. Consistent with differential MUP expression, we observed more nuclear GR in DR mice than in RSV-supplemented and AL control mice with no difference between RSV and AL. These findings point to the notion that, in mice, RSV does not mimic DR in terms of differential MUP expression.

Non-Thermal Plasma Induces Antileukemic Effect Through mTOR Ubiquitination

Non-thermal plasma (NTP) has been studied as a novel therapeutic tool for cancer that does not damage healthy cells. In this study, we show that NTP-treated solutions (NTS) can induce death in various leukemia cells through mechanistic target of rapamycin (mTOR) ubiquitination. Previously, we manufactured and demonstrated the efficacy of NTS in solid cancers. NTS did not exhibit any deleterious side effects, such as acute death or weight loss in nude mice. In the present study, NTS induced cell death in myeloid leukemia cells, including acute myeloid leukemia (AML) and chronic myeloid leukemia (CML). We found that mTOR was downregulated in NTS-treated cells via the ubiquitin-proteasome system (UPS). We also identified ‘really interesting new gene’ finger protein 126 (RNF126) as a novel binding protein for mTOR through protein arrays and determined the role of E3 ligase in NTS-induced mTOR ubiquitination. NTS-derived reactive oxygen species (ROS) affected RNF126 expression and lysosomal dysfunction. These findings suggest that NTS has potential antileukemic effects through RNF126-mediated mTOR ubiquitination with no deleterious side effects. Thus, NTS may represent a new therapeutic method for chemotherapy-resistant leukemia.

A nutritional memory effect counteracts benefits of dietary restriction in old mice

Dietary restriction (DR) during adulthood can greatly extend lifespan and improve metabolic health in diverse species. However, whether DR in mammals is still effective when applied for the first time at old age remains elusive. Here, we report results of a late-life DR switch experiment employing 800 mice, in which 24 months old female mice were switched from ad libitum (AL) to DR or vice versa. Strikingly, the switch from DR-to-AL acutely increases mortality, whereas the switch from AL-to-DR causes only a weak and gradual increase in survival, suggesting a memory of earlier nutrition. RNA-seq profiling in liver, brown (BAT) and white adipose tissue (WAT) demonstrate a largely refractory transcriptional and metabolic response to DR after AL feeding in fat tissue, particularly in WAT, and a proinflammatory signature in aged preadipocytes, which is prevented by chronic DR feeding. Our results provide evidence for a nutritional memory as a limiting factor for DR-induced longevity and metabolic remodeling of WAT in mammals.

An emerging trend of rapid increase of leukemia but not all cancers in the aging population in the United States

The “baby boomers” born in 1946–1964 in the United States (U.S.) started to reach the age of 65 in 2011, rapidly accelerating U.S. population aging. There are great public concerns about its impact on health care with anticipation of rising cancer incidences. We examined the incidences and deaths of leukemia and overall cancer in the U.S. from 1998 to 2018. The acute myeloid leukemia (AML) and chronic myeloid leukemia (CML) incidences remained constant prior to 2011 but have climbed up substantially since then, and the chronic lymphocytic leukemia (CLL) incidence has increased continuously since 1998. The significant increase of myeloid leukemia and CLL incidences was strongly correlated with the U.S. population aging. The incidence of all cancers was increased in correlation with a small increase in aging population prior to 2011, but surprisingly has changed marginally since 2011, which was not significantly correlated with the accelerated population aging. We observed the most substantial decline of deaths with CML, whereas AML deaths continued to rise in the past 20 years. In conclusion, the overall cancer incidence was not increased as fast as previously feared with aging Americans; however, the incidences of myeloid leukemia and CLL significantly outpaced that of all cancers.

Caloric restriction reduces basal cell proliferation and results in the deterioration of neuroepithelial regeneration following olfactotoxic mucosal damage in mouse olfactory mucosa

The effects of caloric restriction (CR) on cell dynamics and gene expression in the mouse olfactory neuroepithelium are evaluated. Eight-week-old male C57BL/6 mice were fed either control pellets (104 kcal/week) or CR pellets (67 kcal/week). The cytoarchitecture of the olfactory neuroepithelium in the uninjured condition and its regeneration after injury by an olfactotoxic chemical, methimazole, were compared between mice fed with the control and CR diets. In the uninjured condition, there were significantly fewer olfactory marker protein (OMP)-positive olfactory receptor neurons and Ki67-positive proliferating basal cells at 3 months in the CR group than in the control group. The number of Ki67-positive basal cells increased after methimazole-induced mucosal injury in both the control and the CR groups, but the increase was less robust in the CR group. The recovery of the neuroepithelium at 2 months after methimazole administration was less complete in the CR group than in the control group. These histological changes were region-specific. The decrease in the OMP-positive neurons was prominent in the anterior region of the olfactory mucosa. Gene expression analysis using a DNA microarray and quantitative real-time polymerase chain reaction demonstrated that the expression levels of two inflammatory cytokines, interleukin-6 and chemokine ligand 1, were elevated in the olfactory mucosa of the CR group compared with the control group. These findings suggest that CR may be disadvantageous to the maintenance of the olfactory neuroepithelium, especially when it is injured.

Resveratrol, lunularin and dihydroresveratrol do not act as caloric restriction mimetics when administered intraperitoneally in mice

Resveratrol as well as caloric restriction were shown to extend lifespan in some model organisms and may possibly delay onset of ageing-related diseases in humans. Yet, resveratrol supplementation does not always extend lifespan of animal models or improve health status of humans. Because of interindividual differences in human microbiota, resveratrol metabolite production in the gut differs. While some individuals produce lunularin and dihydroresveratrol in their gut, others produce dihydroresveratrol only. Therefore, we addressed the question whether these metabolites differ in their biological impact on ageing and intraperitoneally injected 13-month-old C57BL/6JRj mice on an ad-libitum (AL) HFD with resveratrol, dihydroresveratrol or lunularin (24 mg/kg bodyweight; 3 times/week). Compared to mice injected with vehicle (AL-control), resveratrol and dihydroresveratrol did not change bodyweight and had no impact on insulin or glucose levels while lunularin slightly reduced feed intake and bodyweight gain. CR-mice showed lowered cholesterol, insulin and leptin levels, elevated adiponectin and phosphorylated AMPK levels in liver as well as increased transcription of Pck1 and Pgc1α when compared to the AL-control. In contrast, injections with the test substances did not change these parameters. We therefore conclude that in our model, resveratrol, lunularin and dihydroresveratrol did not act as CR mimetics.

Update on the human and mouse lipocalin (LCN) gene family, including evidence the mouse Mup cluster is result of an "evolutionary bloom"

Lipocalins (LCNs) are members of a family of evolutionarily conserved genes present in all kingdoms of life. There are 19 LCN-like genes in the human genome, and 45 Lcn-like genes in the mouse genome, which include 22 major urinary protein (Mup) genes. The Mup genes, plus 29 of 30 Mup-ps pseudogenes, are all located together on chromosome (Chr) 4; evidence points to an “evolutionary bloom” that resulted in this Mup cluster in mouse, syntenic to the human Chr 9q32 locus at which a single MUPP pseudogene is located. LCNs play important roles in physiological processes by binding and transporting small hydrophobic molecules —such as steroid hormones, odorants, retinoids, and lipids—in plasma and other body fluids. LCNs are extensively used in clinical practice as biochemical markers. LCN-like proteins (18–40 kDa) have the characteristic eight β-strands creating a barrel structure that houses the binding-site; LCNs are synthesized in the liver as well as various secretory tissues. In rodents, MUPs are involved in communication of information in urine-derived scent marks, serving as signatures of individual identity, or as kairomones (to elicit fear behavior). MUPs also participate in regulation of glucose and lipid metabolism via a mechanism not well understood. Although much has been learned about LCNs and MUPs in recent years, more research is necessary to allow better understanding of their physiological functions, as well as their involvement in clinical disorders.

An integrative theory for cancer (Review)

In the integrative theory, chronic irritations induce tumors with genetic alterations and rapid proliferative ability. Tumor cells reprogram the metabolism and employ aerobic glycolysis to sustain rapid growth. The host provides both the nutrients and exhaust system to support tumor growth via the tumor microenvironment. Under certain conditions, such as aging, diabetes, obesity and a high‑fat diet, the exhaust system is impaired, triggering a metabolic imbalance between the tumor and host. This is similar to a problematic car with an advanced motor with an out‑of‑date exhaust system. The metabolic imbalance causes a metabolic catastrophe, making tumor cells reside in a dismal environment and forcing them to invade, metastasize and undergo necrosis. Tumor necrosis, particularly in metastases, leads to non‑specific systemic inflammation, which is the major cause of cancer‑related mortality. On the whole, the integrative theory views cancer in an integrative manner and proposes that both genetic alterations and tumor‑host interaction as regards metabolism and immunology determine the destiny of the tumor and host. Although cancer is a genetic disease, tumor biology is basically the nature of the host.

Plasticity of lifelong calorie-restricted C57BL/6J mice in adapting to a medium-fat diet intervention at old age

Calorie restriction (CR) is a dietary regimen that supports healthy aging. In this study, we investigated the systemic and liver‐specific responses caused by a diet switch to a medium‐fat (MF) diet in 24‐month‐old lifelong, CR‐exposed mice. This study aimed to increase the knowledge base on dietary alterations of gerontological relevance. Nine‐week‐old C57BL/6J mice were exposed either to a control, CR, or MF diet. At the age of 24 months, a subset of mice of the CR group was transferred to ad libitumMF feeding (CR‐MF). The mice were sacrificed at the age of 28 months, and then, biochemical and molecular analyses were performed. Our results showed that, despite the long‐term exposure to the CR regimen, mice in the CR‐MF group displayed hyperphagia, rapid weight gain, and hepatic steatosis. However, no hepatic fibrosis/injury or alteration in CR‐improved survival was observed in the diet switch group. The liver transcriptomic profile of CR‐MF mice largely shifted to a profile similar to the MF‐fed animals but leaving ~22% of the 1,578 differentially regulated genes between the CR and MF diet groups comparable with the expression of the lifelong CR group. Therefore, although the diet switch was performed at an old age, the CR‐MF‐exposed mice showed plasticity in coping with the challenge of a MF diet without developing severe liver pathologies.

Effect of caloric restriction on depression

Recently, most of evidence shows that caloric restriction could induce antidepressant‐like effects in animal model of depression. Based on studies of the brain–gut axis, some signal pathways were common between the control of caloric restriction and depression. However, the specific mechanism of the antidepressant‐like effects induced by caloric restriction remains unclear. Therefore, in this article, we summarized clinical and experimental studies of caloric restriction on depression. This review may provide a new therapeutic strategy for depression.

Caloric Restriction Study Design Limitations in Rodent and Nonhuman Primate Studies

For a century, we have known that caloric restriction influences aging in many species. However, only recently it was firmly established that the effect is not entirely dependent on the calories provided. Instead, rodent and nonhuman primate models have shown that the rate of aging depends on other variables, including the macronutrient composition of the diet, the amount of time spent in the restricted state, age of onset, the gender and genetic background, and the particular feeding protocol for the control group. The field is further complicated when attempts are made to compare studies across different laboratories, which seemingly contradict each other. Here, we argue that some of the contradictory findings are most likely due to methodological differences. This review focuses on the four methodological differences identified in a recent comparative report from the National Institute on Aging and University of Wisconsin nonhuman primate studies, namely feeding regimen, diet composition, age of onset, and genetics. These factors, that may be influencing the effects of a calorie restriction intervention, are highlighted in the rodent model to draw parallels and elucidate findings reported in a higher species, nonhuman primates.

Muscle Stem Cells and Aging

Satellite cells (SCs) are a population of muscle-resident stem cells that are essential for efficient tissue repair. SCs reside in a relatively quiescent state during normal tissue turnover, but are activated in response to injury through the microenvironment and cell-intrinsic signals. During aging, SC dysfunction is a major contributor to the decline in regenerative potential of muscle tissue. Recent studies have demonstrated that both cell-intrinsic and cell-extrinsic factors are deregulated during aging. Interventions that reverse age-associated changes in SCs or the niche have shown to partially rejuvenate the regenerative capacity of aged muscle SCs. In this review, we discuss recent advances in SC biology as it pertains to the deleterious effects of aging. A better understanding of how age-dependent changes in the SC and its environment niche impact muscle regeneration could lead to interventions to ameliorate the effects of aging in humans.

Calorie restriction in rodents: Caveats to consider

The calorie restriction paradigm has provided one of the most widely used and most useful tools for investigating mechanisms of aging and longevity. By far, rodent models have been employed most often in these endeavors. Over decades of investigation, claims have been made that the paradigm produces the most robust demonstration that aging is malleable. In the current review of the rodent literature, we present arguments that question the robustness of the paradigm to increase lifespan and healthspan. Specifically, there are several questions to consider as follows: (1) At what age does CR no longer produce benefits? (2) Does CR attenuate cognitive decline? (3) Are there negative effects of CR, including effects on bone health, wound healing, and response to infection? (4) How important is schedule of feeding? (5) How long does CR need to be imposed to be effective? (6) How do genotype and gender influence CR? (7) What role does dietary composition play? Consideration of these questions produce many caveats that should guide future investigations to move the field forward.

Identification of a T cell gene expression clock obtained by exploiting a MZ twin design

Many studies investigated age-related changes in gene expression of different tissues, with scarce agreement due to the high number of affecting factors. Similarly, no consensus has been reached on which genes change expression as a function of age and not because of environment. In this study we analysed gene expression of T lymphocytes from 27 healthy monozygotic twin couples, with ages ranging over whole adult lifespan (22 to 98 years). This unique experimental design allowed us to identify genes involved in normative aging, which expression changes independently from environmental factors. We obtained a transcriptomic signature with 125 genes, from which chronological age can be estimated. This signature has been tested in two datasets of same cell type hybridized over two different platforms, showing a significantly better performance compared to random signatures. Moreover, the same signature was applied on a dataset from a different cell type (human muscle). A lower performance was obtained, indicating the possibility that the signature is T cell-specific. As a whole our results suggest that this approach can be useful to identify age-modulated genes.

Effect of dietary restriction and subsequent re-alimentation on the transcriptional profile of bovine ruminal epithelium

Compensatory growth (CG) is utilised worldwide in beef production systems as a management approach to reduce feed costs. However the underlying biology regulating the expression of CG remains to be fully elucidated. The objective of this study was to examine the effect of dietary restriction and subsequent re-alimentation induced CG on the global gene expression profile of ruminal epithelial papillae. Holstein Friesian bulls (n = 60) were assigned to one of two groups: restricted feed allowance (RES; n = 30) for 125 days (Period 1) followed by ad libitum access to feed for 55 days (Period 2) or (ii) ad libitum access to feed throughout (ADLIB; n = 30). At the end of each period, 15 animals from each treatment were slaughtered and rumen papillae harvested. mRNA was isolated from all papillae samples collected. cDNA libraries were then prepared and sequenced. Resultant reads were subsequently analysed bioinformatically and differentially expressed genes (DEGs) are defined as having a Benjamini-Hochberg P value of <0.05. During re-alimentation in Period 2, RES animals displayed CG, growing at 1.8 times the rate of their ADLIB contemporary animals in Period 2 (P < 0.001). At the end of Period 1, 64 DEGs were identified between RES and ADLIB, with only one DEG identified at the end of Period 2. When analysed within RES treatment (RES, Period 2 v Period 1), 411 DEGs were evident. Genes identified as differentially expressed in response to both dietary restriction and subsequent CG included those involved in processes such as cellular interactions and transport, protein folding and gene expression, as well as immune response. This study provides an insight into the molecular mechanisms underlying the expression of CG in rumen papillae of cattle; however the results suggest that the role of the ruminal epithelium in supporting overall animal CG may have declined by day 55 of re-alimentation.

Intermittent calorie restriction largely counteracts the adverse health effects of a moderate-fat diet in aging C57BL/6J mice

SCOPE

Calorie restriction (CR) has been shown to extend life- and health-span in model species. For most humans, a life-long CR diet is too arduous to adhere to. The aim of this study was to explore whether weekly intermittent CR can (1) provide long-term beneficial effects and (2) counteract diet-induced obesity in male aging mice.

METHODS AND RESULTS

In this study, we have exposed C57Bl/6J mice for 24 months to an intermittent (INT) diet, alternating weekly between CR of a control diet and ad libitum moderate-fat (MF) feeding. This weekly intermittent CR significantly counteracted the adverse effects of the MF diet on mortality, body weight, and liver health markers in 24-month-old male mice. Hepatic gene expression profiles of INT-exposed animals appeared much more comparable to CR- than to MF-exposed mice. At 12 months of age, a subgroup of MF-exposed mice was transferred to the INT diet. Gene expression profiles in the liver of the 24-month-old diet switch mice were highly similar to the INT-exposed mice. However, a small subset of genes was consistently changed by the MF diet during the first phase of life.

CONCLUSION

Weekly intermittent CR largely, but not completely, reversed adverse effects caused by a MF diet.

Epigenetic Mechanisms of Longevity and Aging

Aging is an inevitable outcome of life, characterized by progressive decline in tissue and organ function and increased risk of mortality. Accumulating evidence links aging to genetic and epigenetic alterations. Given the reversible nature of epigenetic mechanisms, these pathways provide promising avenues for therapeutics against age-related decline and disease. In this review, we provide a comprehensive overview of epigenetic studies from invertebrate organisms, vertebrate models, tissues, and in vitro systems. We establish links between common operative aging pathways and hallmark chromatin signatures that can be used to identify "druggable" targets to counter human aging and age-related disease.

Nutritional limitation in early postnatal life and its effect on aging and longevity in rodents

Nutrient limitation in the form of chronic dietary restriction (DR), or more specifically a life-long reduction of total daily nutritional intake, was first shown to extend longevity in rats more than eight decades ago and is one of the most robust anti-aging interventions known. More recently, it has become apparent that dietary restriction limited to only the first few weeks of life in rodents is also capable of significantly impacting aging and longevity. The imposition of nutrient limitation is often achieved via the manipulation of litter size or the modulation of maternal nutrient intake during the lactational period. Not surprisingly, nutrient limited pups are smaller at weaning, and remain so throughout their life, while exhibiting signs of slowed aging. In this review, we discuss potential mechanisms that account for the anti-aging effects of postnatal undernutrition with an emphasis on those pathways that parallel changes seen with chronic DR.

Omega-3 fatty acids partially revert the metabolic gene expression profile induced by long-term calorie restriction

Calorie restriction (CR) consistently extends longevity and delays age-related diseases across several animal models. We have previously shown that different dietary fat sources can modulate life span and mitochondrial ultrastructure, function and membrane fatty acid composition in mice maintained on a 40% CR. In particular, animals consuming lard as the main fat source (CR-Lard) lived longer than CR mice consuming diets with soybean oil (CR-Soy) or fish oil (CR-Fish) as the predominant lipid source. In the present work, a transcriptomic analysis in the liver and skeletal muscle was performed in order to elucidate possible mechanisms underlying the changes in energy metabolism and longevity induced by dietary fat in CR mice. After 8 months of CR, transcription downstream of several mediators of inflammation was inhibited in liver. In contrast, proinflammatory signaling was increased in the CR-Fish versus other CR groups. Dietary fish oil induced a gene expression pattern consistent with increased transcriptional regulation by several cytokines (TNF, GM-CSF, TGF-β) and sex hormones when compared to the other CR groups. The CR-Fish also had lower expression of genes involved in fatty acid biosynthesis and increased expression of mitochondrial and peroxisomal fatty acid β-oxidation genes than the other CR diet groups. Our data suggest that a diet high in n-3 PUFA, partially reverts CR-related changes in gene expression of key processes, such as inflammation and steroid hormone signaling, and this may mitigate life span extension with CR in mice consuming diets high in fish oil.

Preoperative dietary restriction reduces intimal hyperplasia and protects from ischemia-reperfusion injury

OBJECTIVE

Whereas chronic overnutrition is a risk factor for surgical complications, long-term dietary restriction (reduced food intake without malnutrition) protects in preclinical models of surgical stress. Building on the emerging concept that acute preoperative dietary perturbations can affect the body's response to surgical stress, we hypothesized that short-term high-fat diet (HFD) feeding before surgery is detrimental, whereas short-term nutrient/energy restriction before surgery can reverse negative outcomes. We tested this hypothesis in two distinct murine models of vascular surgical injury, ischemia-reperfusion (IR) and intimal hyperplasia (IH).

METHODS

Short-term overnutrition was achieved by feeding mice a HFD consisting of 60% calories from fat for 2 weeks. Short-term dietary restriction consisted of either 1 week of restricted access to a protein-free diet (protein/energy restriction) or 3 days of water-only fasting immediately before surgery; after surgery, all mice were given ad libitum access to a complete diet. To assess the impact of preoperative nutrition on surgical outcome, mice were challenged in one of two fundamentally distinct surgical injury models: IR injury to either kidney or liver, or a carotid focal stenosis model of IH.

RESULTS

Three days of fasting or 1 week of preoperative protein/energy restriction attenuated IH development measured 28 days after focal carotid stenosis. One week of preoperative protein/energy restriction also reduced plasma urea, creatinine, and damage to the corticomedullary junction after renal IR and decreased aspartate transaminase, alanine transaminase, and hemorrhagic necrosis after hepatic IR. However, exposure to a HFD for 2 weeks before surgery had no significant impact on kidney or hepatic function after IR or IH after focal carotid stenosis.

CONCLUSIONS

Short-term dietary restriction immediately before surgery significantly attenuated the vascular wall hyperplastic response and improved IR outcome. The findings suggest plasticity in the body's response to these vascular surgical injuries that can be manipulated by novel yet practical preoperative dietary interventions.

Effects of food variability on growth and reproduction of Aedes aegypti

Despite a large body of knowledge about the evolution of life histories, we know little about how variable food availability during an individual's development affects its life history. We measured the effects of manipulating food levels during early and late larval development of the mosquito Aedes aegypti on its growth rate, life history and reproductive success. Switching from low to high food led to compensatory growth: individuals grew more rapidly during late larval development and emerged at a size close to that of mosquitoes consistently reared at high food. However, switching to high food had very little effect on longevity, and fecundity and reproductive success were considerably lower than in consistently well-fed mosquitoes. Changing from high to low food led to adults with similar size as in consistently badly nourished mosquitoes, but even lower fecundity and reproductive success. A rapid response of growth to changing resources can thus have unexpected effects in later life and in lifetime reproductive success. More generally, our study emphasizes the importance of varying developmental conditions for the evolutionary pressures underlying life-history evolution.

Circulating microRNA signature of genotype-by-age interactions in the long-lived Ames dwarf mouse

Recent evidence demonstrates that serum levels of specific miRNAs significantly change with age. The ability of circulating sncRNAs to act as signaling molecules and regulate a broad spectrum of cellular functions implicates them as key players in the aging process. To discover circulating sncRNAs that impact aging in the long‐lived Ames dwarf mice, we conducted deep sequencing of small RNAs extracted from serum of young and old mice. Our analysis showed genotype‐specific changes in the circulating levels of 21 miRNAs during aging [genotype‐by‐age interaction (GbA)]. Genotype‐by‐age miRNAs showed four distinct expression patterns and significant overtargeting of transcripts involved in age‐related processes. Functional enrichment analysis of putative and validated miRNA targets highlighted cellular processes such as tumor suppression, anti‐inflammatory response, and modulation of Wnt, insulin, mTOR, and MAPK signaling pathways, among others. The comparative analysis of circulating GbA miRNAs in Ames mice with circulating miRNAs modulated by calorie restriction (CR) in another long‐lived mouse suggests CR‐like and CR‐independent mechanisms contributing to longevity in the Ames mouse. In conclusion, we showed for the first time a signature of circulating miRNAs modulated by age in the long‐lived Ames mouse.

Systems biology approaches to study the molecular effects of caloric restriction and polyphenols on aging processes

Worldwide population is aging, and a large part of the growing burden associated with age-related conditions can be prevented or delayed by promoting healthy lifestyle and normalizing metabolic risk factors. However, a better understanding of the pleiotropic effects of available nutritional interventions and their influence on the multiple processes affected by aging is needed to select and implement the most promising actions. New methods of analysis are required to tackle the complexity of the interplay between nutritional interventions and aging, and to make sense of a growing amount of -omics data being produced for this purpose. In this paper, we review how various systems biology-inspired methods of analysis can be applied to the study of the molecular basis of nutritional interventions promoting healthy aging, notably caloric restriction and polyphenol supplementation. We specifically focus on the role that different versions of network analysis, molecular signature identification and multi-omics data integration are playing in elucidating the complex mechanisms underlying nutrition, and provide some examples on how to extend the application of these methods using available microarray data.

Six-month Calorie Restriction in Overweight Individuals Elicits Transcriptomic Response in Subcutaneous Adipose Tissue That is Distinct From Effects of Energy Deficit

Calorie restriction confers health benefits distinct from energy deficit by exercise. We characterized the adipose-transcriptome to investigate the molecular basis of the differential phenotypic responses. Abdominal subcutaneous fat was collected from 24 overweight participants randomized in three groups (N = 8/group): weight maintenance (control), 25% energy deficit by calorie restriction alone (CR), and 25% energy deficit by calorie restriction with structured exercise (CREX). Within each group, gene expression was compared between 6 months and baseline with cutoffs at nominal p ≤ .01 and absolute fold-change ≥ 1.5. Gene-set enrichment analysis (false discovery rate < 5%) was used to identify significantly regulated biological pathways. CR and CREX elicited similar overall clinical response to energy deficit and a comparable reduction in gene transcription specific to oxidative phosphorylation and proteasome function. CR vastly outweighed CREX in the number of differentially regulated genes (88 vs 39) and pathways (28 vs 6). CR specifically downregulated the chemokine signaling-related pathways. Among the CR-regulated genes, 27 functioned as transcription/translation regulators (eg, mRNA processing or transcription/translation initiation), whereas CREX regulated only one gene in this category. Our data suggest that CR has a broader effect on the transcriptome compared with CREX which may mediate its specific impact on delaying primary aging.

Rapamycin-induced metabolic defects are reversible in both lean and obese mice

The inhibition of mTOR (mechanistic target of rapamycin) by the macrolide rapamycin has many beneficial effects in mice, including extension of lifespan and reduction or prevention of several age-related diseases. At the same time, chronic rapamycin treatment causes impairments in glucose metabolism including hyperglycemia, glucose intolerance and insulin resistance. It is unknown whether these metabolic effects of rapamycin are permanent or whether they can be alleviated. Here, we confirmed that rapamycin causes glucose intolerance and insulin resistance in both inbred and genetically heterogeneous mice fed either low fat or high fat diets, suggesting that these effects of rapamycin are independent of genetic background. Importantly, we also found that these effects were almost completely lost within a few weeks of cessation of treatment, showing that chronic rapamycin treatment does not induce permanent impairment of glucose metabolism. Somewhat surprisingly, chronic rapamycin also promoted increased accumulation of adipose tissue in high fat fed mice. However, this effect too was lost when rapamycin treatment was ended suggesting that this effect of rapamycin is also not permanent. The reversible nature of rapamycin's alterations of metabolic function suggests that these potentially detrimental side-effects might be managed through alternative dosing strategies or concurrent treatment options.

Cardioprotective Signature of Short-Term Caloric Restriction

Objective

To understand the molecular pathways underlying the cardiac preconditioning effect of short-term caloric restriction (CR).

Background

Lifelong CR has been suggested to reduce the incidence of cardiovascular disease through a variety of mechanisms. However, prolonged adherence to a CR life-style is difficult. Here we reveal the pathways that are modulated by short-term CR, which are associated with protection of the mouse heart from ischemia.

Methods

Male 10-12 wk old C57bl/6 mice were randomly assigned to an ad libitum (AL) diet with free access to regular chow, or CR, receiving 30% less food for 7 days (d), prior to myocardial infarction (MI) via permanent coronary ligation. At d8, the left ventricles (LV) of AL and CR mice were collected for Western blot, mRNA and microRNA (miR) analyses to identify cardioprotective gene expression signatures. In separate groups, infarct size, cardiac hemodynamics and protein abundance of caspase 3 was measured at d2 post-MI.

Results

This short-term model of CR was associated with cardio-protection, as evidenced by decreased infarct size (18.5±2.4% vs. 26.6±1.7%, N=10/group; P=0.01). mRNA and miR profiles pre-MI (N=5/group) identified genes modulated by short-term CR to be associated with circadian clock, oxidative stress, immune function, apoptosis, metabolism, angiogenesis, cytoskeleton and extracellular matrix (ECM). Western blots pre-MI revealed CR-associated increases in phosphorylated Akt and GSK3ß, reduced levels of phosphorylated AMPK and mitochondrial related proteins PGC-1α, cytochrome C and cyclooxygenase (COX) IV, with no differences in the levels of phosphorylated eNOS or MAPK (ERK1/2; p38). CR regimen was also associated with reduced protein abundance of cleaved caspase 3 in the infarcted heart and improved cardiac function.

Noncoding RNA in age-related cardiovascular diseases

Eukaryotic gene expression is tightly regulated transcriptionally and post-transcriptionally by a host of noncoding (nc)RNAs. The best-studied class of short ncRNAs, microRNAs, mainly repress gene expression post-transcriptionally. Long noncoding (lnc)RNAs, which comprise RNAs differing widely in length and function, can regulate gene transcription as well as post-transcriptional mRNA fate. Collectively, ncRNAs affect a broad range of age-related physiologic deteriorations and pathologies, including reduced cardiovascular vigor and age-associated cardiovascular disease. This review presents an update of our understanding of regulatory ncRNAs contributing to cardiovascular health and disease as a function of advancing age. We will discuss (1) regulatory ncRNAs that control aging-associated cardiovascular homeostasis and disease, (2) the concepts, approaches, and methodologies needed to study regulatory ncRNAs in cardiovascular aging and (3) the challenges and opportunities that age-associated regulatory ncRNAs present in cardiovascular physiology and pathology. This article is part of a Special Issue entitled "CV Aging".

The use of animal models to decipher physiological and neurobiological alterations of anorexia nervosa patients

Extensive studies were performed to decipher the mechanisms regulating feeding due to the worldwide obesity pandemy and its complications. The data obtained might be adapted to another disorder related to alteration of food intake, the restrictive anorexia nervosa. This multifactorial disease with a complex and unknown etiology is considered as an awful eating disorder since the chronic refusal to eat leads to severe, and sometimes, irreversible complications for the whole organism, until death. There is an urgent need to better understand the different aspects of the disease to develop novel approaches complementary to the usual psychological therapies. For this purpose, the use of pertinent animal models becomes a necessity. We present here the various rodent models described in the literature that might be used to dissect central and peripheral mechanisms involved in the adaptation to deficient energy supplies and/or the maintenance of physiological alterations on the long term. Data obtained from the spontaneous or engineered genetic models permit to better apprehend the implication of one signaling system (hormone, neuropeptide, neurotransmitter) in the development of several symptoms observed in anorexia nervosa. As example, mutations in the ghrelin, serotonin, dopamine pathways lead to alterations that mimic the phenotype, but compensatory mechanisms often occur rendering necessary the use of more selective gene strategies. Until now, environmental animal models based on one or several inducing factors like diet restriction, stress, or physical activity mimicked more extensively central and peripheral alterations decribed in anorexia nervosa. They bring significant data on feeding behavior, energy expenditure, and central circuit alterations. Animal models are described and criticized on the basis of the criteria of validity for anorexia nervosa.

Caloric restriction reveals a metabolomic and lipidomic signature in liver of male mice

Lipid composition, particularly membrane unsaturation, has been proposed as being a lifespan determinant, but it is currently unknown whether caloric restriction (CR), an accepted life-extending intervention, affects cellular lipid profiles. In this study, we employ a liquid chromatography quadrupole time-of-flight-based methodology to demonstrate that CR in the liver of male C57BL/6 mice: (i) induces marked changes in the cellular lipidome, (ii) specifically reduces levels of a phospholipid peroxidation product, 1-palmitoyl-2-glutaryl-sn-glycero-3-phosphatidylcholine, (iii) alters cellular phosphoethanolamine and triglyceride distributional profiles, (iv) affects mitochondrial electron transport chain complexes, increasing complex II and decreasing complex III and (v) is associated with specific changes in liver metabolic pathways. These data demonstrate that CR induces a specific lipidome and metabolome reprogramming event in mouse liver which is associated with lower protein oxidative damage, as assessed by mass spectrometry-based measurements. Such changes may be critical to the increased lifespan and healthspan observed in C57BL/6 mice following CR.

Circulating small noncoding RNAs as biomarkers of aging

Small noncoding RNAs (sncRNAs) mediate a variety of cellular functions in animals and plants. Deep sequencing has made it possible to obtain highly detailed information on the types and abundance of sncRNAs in biological specimens, leading to the discovery that sncRNAs circulate in the blood of humans and mammals. The most abundant types of circulating sncRNAs are microRNAs (miRNAs), 5' transfer RNA (tRNA) halves, and YRNA fragments, with minute amounts of other types that may nevertheless be significant. Of the more abundant circulating sncRNAs only miRNAs have well described functions, but characteristics of the others suggest specific processing and secretion as complexes that protect the RNA from degradation. The properties of circulating sncRNAs are consistent with their serving as signaling molecules, and investigations of circulating miRNAs support the view that they can enter cells and regulate cellular functions. The serum levels of specific sncRNAs change markedly with age, and these changes can be mitigated by calorie restriction (CR), indicating that levels are under physiologic control. The ability of circulating sncRNAs to transmit functions between cells and to regulate a broad spectrum of cellular functions, and the changes in their levels with age, implicate them in the manifestations of aging. Our understanding of the functions of circulating sncRNA, particularly in relation to aging, is currently at a very early stage; results to date suggest that more extensive investigation will yield important insights into mechanisms of aging.

Biophysical and biological meanings of healthspan from C. elegans cohort

Lifespan among individuals ranges widely in organisms from yeast to mammals, even in an isogenic cohort born in a nearly uniform environment. Needless to say, genetic and environmental factors are essential for aging and lifespan, but in addition, a third factor or the existence of a stochastic element must be reflected in aging and lifespan. An essential point is that lifespan or aging is an unpredictable phenomenon. The present study focuses on elucidating the biophysical and biological meanings of healthspan that latently indwells a stochastic nature. To perform this purpose, the nematode Caenorhabditis elegans served as a model animal. C. elegans fed a healthy food had an extended healthspan as compared to those fed a conventional diet. Then, utilizing this phenomenon, we clarified a mechanism of healthspan extension by measuring the single-worm ATP and estimating the ATP noise (or the variability of the ATP content) among individual worms and by quantitatively analyzing biodemographic data with the lifespan equation that was derived from a fluctuation theory.

Long-term physiological alterations and recovery in a mouse model of separation associated with time-restricted feeding: a tool to study anorexia nervosa related consequences

Background

Anorexia nervosa is a primary psychiatric disorder, with non-negligible rates of mortality and morbidity. Some of the related alterations could participate in a vicious cycle limiting the recovery. Animal models mimicking various physiological alterations related to anorexia nervosa are necessary to provide better strategies of treatment.

Aim

To explore physiological alterations and recovery in a long-term mouse model mimicking numerous consequences of severe anorexia nervosa.

Methods

C57Bl/6 female mice were submitted to a separation-based anorexia protocol combining separation and time-restricted feeding for 10 weeks. Thereafter, mice were housed in standard conditions for 10 weeks. Body weight, food intake, body composition, plasma levels of leptin, adiponectin, IGF-1, blood levels of GH, reproductive function and glucose tolerance were followed. Gene expression of several markers of lipid and energy metabolism was assayed in adipose tissues.

Results

Mimicking what is observed in anorexia nervosa patients, and despite a food intake close to that of control mice, separation-based anorexia mice displayed marked alterations in body weight, fat mass, lean mass, bone mass acquisition, reproductive function, GH/IGF-1 axis, and leptinemia. mRNA levels of markers of lipogenesis, lipolysis, and the brown-like adipocyte lineage in subcutaneous adipose tissue were also changed. All these alterations were corrected during the recovery phase, except for the hypoleptinemia that persisted despite the full recovery of fat mass.

Conclusion

This study strongly supports the separation-based anorexia protocol as a valuable model of long-term negative energy balance state that closely mimics various symptoms observed in anorexia nervosa, including metabolic adaptations. Interestingly, during a recovery phase, mice showed a high capacity to normalize these parameters with the exception of plasma leptin levels. It will be interesting therefore to explore further the central and peripheral effects of the uncorrected hypoleptinemia during recovery from separation-based anorexia.

Caloric restriction and cancer: molecular mechanisms and clinical implications

Caloric restriction (CR) is currently the most robust environmental intervention known to increase healthy life and prolong lifespan in several models, from yeast to mice. Although the protective effect of CR on the incidence of cancer is well established, its impact on tumor cell responses to chemotherapeutic treatment is currently being investigated. Interestingly, the molecular mechanisms required to extend lifespan upon reduced food intake are being evaluated, and these mechanisms may offer new opportunities for therapeutic intervention. In addition, new findings suggest a beneficial effect of CR in enhancing the efficiency of tumor cell killing by chemotherapeutic drugs and inducing an anticancer immune response.