Markeers analysis Results are expressed reetriction mean ± Markera. e The Hunger and elderly population of GFP-LC3 redistribution was quantified Maroers conventional fluorescence microscopy mean±S. Galluzzi L, Energy-boosting shots I, Kepp O, Seror C, Hangen E, Perfettini JL et al. In 6-month calorie-restricted animals S6 groupautophagic figure size increased when compared to controls, but no further change was detected with aging. mL -1 ; Sigma-Aldrich during secondary antibody incubation. On a whole-body level. Cells were immunolabeled for LC3B green and MAP2 red, neurons.

Caloric restriction and autophagy markers -

Nevertheless, in a previous analysis carried out in mice, Finley et al. Using electron microscopy, we found an increase in the abundance of IMM from red fibers during aging in control mice, a result that is in contrast with those reported by Leduc-Gaudet et al. More recently, Sayed et al. Although these latter data are in accordance with ours, no mention to fiber type was made in that paper.

Of note, our results have documented that 6 months of CR induced no changes in SMM or IMM content in the S group, but longer periods of CR affected mitochondrial content in different ways depending on dietary fat.

In general, CR mice showed lower mitochondrial content than controls with L18 mice displaying the highest content. As we have shown here, mitochondria with altered structure may be found in subsarcolemmal areas and intermyofibrillar regions in all the experimental groups, but they were not included in our estimation of mitochondrial mass to focus our study towards structurally intact organelles.

The significance of these altered structures will be discussed below. Using mitochondrial complexes as markers of mitochondrial mass, an age-dependent decrease was only demonstrated for Complex I, which is basically in line with previous reports 12 , When we analyzed the effects of CR ie, comparing C vs S groups , the only change concerning mitochondrial complexes was a decrease in Complex III after 18 months of intervention.

Moreover, although 6 months of CR resulted in several changes in the expression levels of mitochondrial complexes depending on the dietary fat, including the increase of complexes II, III, and IV in mice fed diets enriched in PUFA, a longer CR intervention 18 months abolished these changes.

Aging also influences morphometric parameters of individual mitochondria. Leduc-Gaudet et al. These results contrast with those reported here since we found a slight but statistically significant decrease of sizes in SSM and no changes in IMM in control conditions during aging.

However, 6 months of CR induced changes depending on the dietary fat with significantly increased size in both types of mitochondria when lard was used as dietary fat. After 18 months of CR both S18 and especially L18 showed larger mitochondria than F These results seem to point out a specific role of dietary fat on development of mitochondrial size and shape in CR conditions.

In skeletal muscle, it has been proposed that paravascular mitochondria which are equivalent to subsarcolemmal are involved in the generation of proton-motive force near the capillaries and are directly connected to a specific type of IMM called I-band mitochondria, that use the proton-motive force to produce ATP Here, we show that SSM regions from old control mice are larger than those from their CR counterparts.

This may be an age-related adaptive change that produces the advantage of higher contact surface of SSM clusters with IMM, which facilitates the formation of contact between them.

In CR mice, only those fed lard as dietary fat showed this possible advantage. Results showing impaired autophagy during aging in skeletal muscle have been reported 14 , 15 , In our ultrastructural study in red fibers, we found typical autophagosomes and a relatively high number of altered mitochondria depending on the age and dietary intervention.

While autophagosomes were mainly located in subsarcolemmal areas, altered mitochondria were found throughout the sarcoplasm. In general, these structures displayed greater size than nonaltered mitochondria and the possibility exists that their increased size make them unsuitable to be removed by the autophagosome leading to their accumulation inside the fibers, a mechanism previously proposed to explain increased mitochondrial size without changes in mitophagy in muscle fibers from different mammals The possibility of an upper size limit for individual autophagosomes has been previously suggested In rats, Wohlgemuth et al.

However, other studies in mice 34 showed decreased levels of Beclin-1 with no changes in LC3 ratio during aging. Nevertheless, these authors also found significantly increased levels of p62 expression which is associated with a blockade in autophagic activity , suggesting a decrease in autophagic flux during aging.

Except for Beclin1 changes reported by Joseph et al. In our samples, 6 or 18 months of CR induced no changes in Beclin1 expression levels as occurred in CR rats Although some changes were detected after 6 months of CR for LC3 ratio compared to control mice, longer periods of intervention reverted this effect.

On the other hand, 18 months of CR resulted in decreased levels of p62 when compared to control, suggesting a possible unblocking of the autophagy flux. When comparing the different dietary fats, the main detected change was an age-related increase of LC3 ratio in mice fed a diet containing fish oil.

This result may be related to an improvement of the autophagic flux in later age in this dietary group. Pink1 and Parkin are directly related to selective mitophagy.

In our samples, we did not find changes in the levels of these proteins during aging in controls, which agrees with previous observations in aged mice and monkeys In the latter case, Pink1 can interact with Parkin triggering mitophagy In our samples, 6 months of CR resulted in decreased levels of Parkin with no changes in Pink1, especially in mice fed lard as dietary fat and these animals showed the highest accumulation of altered IMM at this time point.

After 18 months of CR, the highest values of Pink1 and Parkin were found in lard group, in which we found increased size of unaltered mitochondrial.

These results seem to indicate that the relative amounts of these proteins can determine the function of Pink1 and mitochondrial fate. The analysis of mitochondrial fusion regulation in relation to aging has yielded contrasting results with a downregulated pattern found in some cases 16 and no changes or even upregulation in others The suggestion was made that these results are compatible with a fusion—fission imbalance in favor of enhanced mitochondrial fusion in aged skeletal muscle Furthermore, in a recent paper, increased levels of both Mfn1 and Mfn2 were reported in mice and monkeys Six months of CR induced increased levels of Mfn2 and OPA1, but no further changes were found after longer periods of CR, suggesting an early control of mitochondrial fusion in calorie restricted animals.

This fact together with the higher expression level of Drp1 at 18 months of CR is probably a part of the regulatory mechanisms of mitochondrial fission and fusion dynamics in CR-mice and seems to operate in a different way that in control animals. Concerning dietary fat in CR-fed mice, the most prominent result was the significative increase of OPA1 during aging in lard group L It is known that OPA1 can be found in long and short forms depending on its cleavage once imported to the mitochondria.

The long form is inserted in the inner mitochondrial membrane facing Mfn1 and Mfn2 proteins and is involved in outer membrane fusion, while the short form contributes to crista junction formation and interacts with several inner membrane components In the present study, only the long form was clearly detected and quantified and, therefore, our results should be interpreted based on its interaction with Mfn1 and Mfn2 to promote mitochondrial fusion.

We show that in skeletal muscle from CR mice, dietary fat influences mitochondrial mass and ultrastructure and may play a role in processes such as auto- and mitophagy and mitochondrial dynamics during aging, with lard showing some advantages compared to soybean and fish oil.

These results are in accordance with previous papers using the same animals as those included here, in which we showed that dietary fat in CR mice differentially improved ultrastructural and physiological parameters in liver and kidney 21 , 22 , with lard showing an optimal effect.

The oldest animals used in this work were month-old reflecting late middle age, and sarcopenia is more apparent in advanced ages 28—30 months.

Although we would hypothesize that all mice would show a decrease in muscle mass and strength with very advanced age, a limitation of the present study is that we were not able to determine the impact of dietary fats on muscle changes in elderly mice.

Moreover, we also have recently reported that muscle strength and endurance is either not altered or improved in mice consuming mildly restricted high fat or ketogenic diets containing lard as the primary dietary fat when compared to a control group consuming a diet with soybean oil as the lipid source These results strongly suggest an interplay between diet composition and CR in life span outcomes in mice.

On the other hand, we have also shown that mitochondrial phospholipid fatty acid composition was altered in liver and skeletal muscle from CR mice in a manner that reflected the unsaturated fatty acid composition of the diet, with the consequent increase of n-3 and n-6 fatty acids in fish and soybean oil fed animals, respectively, potentially changing several properties of the membranes Additionally, lard fed animals showed a significantly higher proportion of mitochondrial monounsaturated fatty acids especially oleic acid , a result that was accompanied by improved mitochondrial functions and ultrastructure Thus, it is very likely that an increase in monounsaturated fatty acids, such as oleic acid, may be involved in the beneficial effect of lard as a dietary fat in CR fed animals.

However, further studies will be required to identify the specific fatty acids which influence muscle mass and function and health and life span in calorie restricted mice at very advanced age.

This study was supported by National Institutes of Health grant 1R01AG to J. and J. were supported by FPU contracts from the Spanish Ministerio de Educación, Cultura y Deporte. was funded by the Spanish Agencia Española de Cooperación Internacional al Desarrollo.

is supported by the Intramural Research Program of the National Institute on Aging. The authors are indebted to the personnel from the Servicio Centralizado de Apoyo a la Investigación SCAI; University of Córdoba for technical support. Johnson ML , Robinson MM , Nair KS. Skeletal muscle aging and the mitochondrion.

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Advanced Search. Search Menu. Article Navigation. Close mobile search navigation Article Navigation. Volume Article Contents Abstract. Material and Methods. Conflict of Interest. Journal Article Editor's Choice. The Impact of Aging, Calorie Restriction and Dietary Fat on Autophagy Markers and Mitochondrial Ultrastructure and Dynamics in Mouse Skeletal Muscle.

Elena Gutiérrez-Casado, BS , Elena Gutiérrez-Casado, BS. Departamento de Biología Celular, Fisiología e Inmunología, Universidad de Córdoba, Campus de Excelencia Internacional Agroalimentario, ceiA3, Spain.

Oxford Academic. Husam Khraiwesh, PhD. Department of Nutrition and Food Processing, Faculty of Agricultural Technology, Al-Balqa Applied University, Al-Salt, Jordan. José A López-Domínguez, PhD.

Jesús Montero-Guisado, BS. Guillermo López-Lluch, PhD. Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide-CSIC, CIBERER, Instituto de Salud Carlos III, Sevilla, Spain. Plácido Navas, PhD. Rafael de Cabo, PhD. Translational Gerontology Branch, National Institute of Aging, National Institutes on Health, Baltimore, Maryland.

Jon J Ramsey, PhD. Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis. José A González-Reyes, PhD. Address correspondence to: José A. González-Reyes, PhD, Departamento de Biología Celular, Fisiología e Inmunología, Universidad de Córdoba, Campus de Rabanales, Edificio Severo Ochoa, 3ª planta, Campus de Excelencia Internacional Agroalimentario, ceiA3, Córdoba, Spain.

E-mail: bc1gorej uco. José M Villalba, PhD. These authors contributed equally to this work. These authors shared last authorship. PDF Split View Views. Select Format Select format.

ris Mendeley, Papers, Zotero. enw EndNote. bibtex BibTex. The actions of ghrelin are mediated through the activation of the G-coupled protein growth hormone secretagogue type 1a receptor GHS-R1a , which also has a wide tissue distribution [ 43 , 46 ].

Ghrelin is involved in the regulation of cardiovascular functions, bone metabolism and inflammation [ 47 , 48 ]. Ghrelin is also involved in memory and learning and has a neuroprotective effect in neurodegenerative diseases and ischemic brain injury models [ 46 , 48 - 52 ].

Since caloric restriction increases autophagy and both NPY and ghrelin, the aim of this study was to investigate whether NPY and ghrelin stimulates autophagy and if these peptides mediate caloric restriction-induced autophagy in rat cortical neurons. Understanding how NPY and ghrelin may act as caloric restriction mimetics by increasing autophagic clearance in cortical neurons, provides a new anti-aging mechanisms of caloric restriction that could be further explored.

To investigate whether caloric restriction regulates autophagy in rat cortical cortical neurons, we monitored autophagy in rat cortical neurons exposed to a caloric restriction mimetic medium referred as caloric restriction hereafter by measuring the protein levels of the transient autophagosomal membrane-bound form of LC3B LC3B-II and sequestosome 1 SQSTM1, also known as p62 , widely used as markers of the autophagic process [ 53 , 54 ].

As shown in Figure 1A and B , caloric restriction increases LC3B puncta immunoreactivity in rat cortical neurons. While untreated cells control cells have a diffuse LC3B cellular distribution, with few small LC3B puncta, in caloric restriction-treated cells an increase in LC3B puncta immunoreactivity was observed, suggesting an increase in autophagosome formation and autophagy induction.

The levels of LC3B-II and SQSTM1 were also measured by Western blotting Figure 1C. The results show that caloric restriction increased LC3B-II protein levels However, an increase in LC3B-II levels and the consequent autophagosome formation does not guarantee an increase of the autophagic activity [ 53 ].

To rule out the possibility that the increase of LC3B puncta immunoreactivity was due to an inhibited auto-phagosome degradation rather than autophagosome formation, we evaluated endogenous autophagic system in the presence or absence of an inhibitor of lysosomal degradation, chloroquine [ 53 - 55 ].

Since LC3B-II and other autophagic substrates, as is the case of SQSTM1, are degraded at the final stages of autophagy, chloroquine treatment will impair their degradation, leading to the accumulation of both LC3B-II and SQSTM1.

In the presence of chloroquine, we observed that the increase of LC3B-II induced by caloric restriction was significantly higher than in cells under caloric restriction without chloroquine Figure 1C. Concomitant with the increase in LC3B-II steady state levels, caloric restriction decreased SQSTM1 protein content in rat cortical neurons Figure 1D.

The SQSTM1 levels were higher in cells under caloric restriction in the presence of chloroquine than in cells under caloric restriction without chloroquine Altogether, these results show that caloric restriction increases autophagic clearance in rat cortical neurons.

Inhibition of MTOR, therefore, results in activation of autophagy [ 57 , 58 ]. MTOR activity can be assessed by the analysis of MTOR phosphorylation at its active site Ser As shown in Figure 1E , caloric restriction decreased phospho-MTOR levels Figure 1.

Caloric restriction increases autophagy in rat cortical neurons. Primary rat cortical neurons were exposed to caloric restriction mimic medium CR , DMEM low glucose, for 6 h.

Untreated cells were used as control Ctrl. A LC3B puncta immunoreactivity was assessed by immunocytochemistry, as described in Materials and Methods. Cells were immunolabeled for LC3B green and MAP2 red.

Nuclei were stained with Hoechst blue. Figures are representative of three independents experiments. Scale bar, 20 μM. Whole cell extracts were assayed for LC3B-II C , SQSTM1 D , phospho-MTOR p-MTOR E and β-tubulin loading control immunoreactivity through Western blotting analysis, as described in Materials and Methods.

Representative Western blots for each protein are presented above each respective graph. The results represent the mean ± SEM of, at least, five independents experiments, and are expressed as percentage of control.

Since caloric restriction was shown to increase the levels of hypothalamic NPY [ 28 - 31 ] and circulating ghrelin [ 39 , 41 , 42 ], we next investigated whether caloric restriction could also regulate the levels of both peptides in rat cortical neurons.

As shown in Figure 2A and B , caloric restriction mimetic medium increased both NPY and ghrelin mRNA levels in primary rat cortical neurons 1. Concomitantly, caloric restriction mimetic medium increased both NPY and ghrelin protein content in primary rat cortical neurons Figure 2.

Caloric restriction increases NPY and ghrelin levels in rat cortical neurons. Primary rat cortical neurons were exposed to caloric restriction medium CR , DMEM low glucose, for 6 h.

A and B Total RNA was isolated and the transcript levels of NPY and ghrelin were analyzed by qRT-PCR, as described in Materials and Methods. The results represent the mean ± SEM of five independents experiments and are expressed as the relative amount compared to control.

The results represent the mean ± SEM of independents experiments and are expressed as the relative amount compared to control. We observed that caloric restriction induces autophagy in rat cortical neurons and this is accompanied by an increase in NPY levels. Given that NPY and NPY receptors are expressed in rat cortical neurons [ 56 ], we hypothesized that NPY receptors could play a role on caloric restriction-induced autophagy in rat cortical neurons.

We observed that NPY Y 1 , Y 2 or Y 5 receptor antagonists inhibited the stimulatory effect of caloric restriction on autophagy markers: the increase in LC3B-II Figure 3A and the decrease in SQSTM1 Figure 3B levels. These results suggest that caloric restriction-induced autophagy in rat cortical neurons is mediated by NPY Y 1 , Y 2 or Y 5 receptor activation.

Figure 3. NPY receptor antagonists inhibit the stimulatory effect of caloric restriction on autophagy in rat cortical neurons. Primary rat cortical neurons were incubated with NPY Y 1 receptor antagonist BIBP Y 1 ant, 1 μM , NPY Y 2 receptor antagonist BIIE Y 2 ant, 1 μM or NPY Y 5 receptor antagonist L, Y 5 ant, 1 μM , 30 min before caloric restriction medium CR for 6 h.

Whole cell extracts were assayed for LC3B-II A , SQSTM1 B and β-tubulin loading control immunoreactivity by Western blotting analysis, as described in Materials and Methods. As the activation of NPY receptors is involved in caloric restriction-induced autophagy, we then investigated the effect of NPY per se on rat cortical neurons autophagy.

We observed that NPY, similarly to caloric restriction, increased LC3B puncta immunoreactivity Figure 4A and B and LC3B-II steady state levels Moreover, in the presence of chloroquine, the increase in LC3B-II levels was higher NPY also decreased SQSTM1 content in rat cortical neurons Figure 4D and this effect was inhibited in the presence of chloroquine.

Moreover, we observed that NPY Y 1 , Y 2 or Y 5 receptor antagonists inhibited LC3B-II increase Figure 4E and SQSTM1 decrease Figure 4F induced by NPY.

Overall, these results show that NPY enhances autophagic activity in rat cortical neurons, through NPY Y 1 , Y 2 or Y 5 receptors activation. As shown in Figure 4G , NPY decreases phospho-MTOR Ser levels Figure 4.

NPY increases autophagy in rat cortical neurons. Primary rat cortical neurons were exposed to NPY nM for 6 h. A LC3B distribution was assessed by immunocytochemistry assay, as described in Materials and Methods.

Cells were immunolabeled for LC3B green and MAP2 red, neurons. Whole cell extracts were assayed for LC3B-II C and E , SQSTM1 D and F , phospho-MTOR p-MTOR G and β-tubulin loading control immunoreactivity through Western blotting analysis, as described in Materials and Methods.

Since caloric restriction increases ghrelin mRNA and protein levels in rat cortical neurons Figure 2B , we hypothesized that ghrelin, similarly to NPY, could be involved in caloric restriction-induced autophagy in rat cortical neurons.

As shown in Figure 5A and B , ghrelin receptor GHS-R1a antagonist [D - Lys 3 ] - GHRP-6 inhibited the increase of LC3B-II and the decrease of SQSTM1, induced by caloric restriction in rat cortical neurons.

These results suggest that ghrelin receptor GHS-R1a mediates, in part, caloric restriction-induced autophagy in rat cortical neurons. Figure 5. Ghrelin mediates caloric restriction-induced autophagy in rat cortical neurons.

Primary rat cortical neurons were treated with GHS-R1a receptor antagonist [D - Lys 3 ] - GHRP-6 GHS-R1a ant, μM 30 min before caloric restriction CR for 6 h. Whole cell extracts were assayed for LC3B-II A , SQSTM1 B and β-tubulin loading control immunoreactivity through Western blotting analysis, as described in Materials and Methods.

We next evaluated the effect of ghrelin per se on autophagy in rat cortical neurons. Similarly to caloric restriction and NPY, in rat cortical neurons, ghrelin induced autophagy and autophagosome formation, as shown by an increase in LC3B puncta immunoreactivity Figure 6A , LC3B-II steady state levels Figure 6B , and autophagic degradation, as shown by SQSTM1 protein decrease Figure 6C and D.

As expected, the GHS-R1a receptor blockage with the ghrelin receptor antagonist [D - Lys 3 ] - GHRP-6 abolished ghrelin stimulatory effects on both autophagic substrates Figure 6E and F. Next, we observed that ghrelin decreased phospho-MTOR levels in rat cortical neurons, suggesting that ghrelin, similarly to caloric restriction and NPY, induced autophagy through the canonical inhibition of MTOR activity Figure 6G.

Figure 6. Ghrelin induces autophagy in rat cortical neurons. Primary rat cortical neurons were exposed to ghrelin GHRL, 10 nM for 6 h. A LC3B cellular distribution was assessed by immunocytochemistry assay, as described in Materials and Methods.

As ghrelin regulates NPY expression in hypothalamic neurons [ 57 ], we hypothesized that ghrelin could also regulate NPY levels in rat cortical neurons.

As shown in Figure 7A and B , ghrelin increased NPY mRNA 1. This interesting observation led us to hypothesize whether NPY receptors activation through endogenous NPY could play a role on ghrelin-induced autophagy in rat cortical neurons.

We observed that NPY Y 1 , Y 2 or Y 5 receptor antagonists significantly decreased autophagy LC3B-II increase and SQSTM1 decrease induced by ghrelin Figure 7C and D These results suggest that ghrelin enhances autophagy in rat cortical neurons, at least partially, by increasing NPY levels and consequently NPY receptors activation.

Figure 7. Ghrelin increases NPY content and NPY receptor antagonists block the stimulatory role of ghrelin on autophagy in rat cortical neurons. Primary rat cortical neuronal cultures were exposed to ghrelin GHRL, 10 nM for 6 h.

A Total RNA was isolated and the transcript levels of NPY were analyzed by qPCR, as described in Materials and Methods. The results represent the mean ± SEM of three independents experiments and are expressed as the relative amount compared to control.

C and D Cells were incubated with NPY Y 1 receptor antagonist BIBP Y 1 ant, 1 μM , NPY Y 2 receptor antagonist BIIE Y 2 ant, 1 μM or NPY Y 5 receptor antagonist L, Y 5 ant, 1 μM , 30 min before ghrelin GHRL, 10 nM treatment for 6 h. Whole cell extracts were assayed for LC3B-II C , SQSTM1 D and β-tubulin loading control immunoreactivity through Western blotting analysis, as described in Materials and Methods.

In the present study, we show, for the first time, that NPY and ghrelin mediate autophagy stimulation induced by caloric restriction in rat cortical neurons. These results are in agreement to recent studies that show autophagy induction in primary cortical neurons upon caloric restriction and in rodent cortical neurons upon short-term food restriction [ 58 , 59 ].

Caloric restriction increases NPY in the hypothalamic neurons and herein we show that caloric restriction also increases NPY levels also in rat cortical neurons [ 29 , 39 ]. In addition, we observed that NPY Y 1 , Y 2 and Y 5 receptor antagonists decreased the stimulatory effect of caloric restriction on autophagy, suggesting that caloric restriction-induced autophagy is dependent on NPY Y 1 , Y 2 or Y 5 receptor activation in rat cortical neurons.

Accordingly, we recently showed that caloric restriction stimulates autophagy in rodent hypothalamic neurons and the NPY Y 1 , Y 2 or Y 5 receptors antagonists inhibits this stimulatory effect of caloric restriction in autophagy [ 39 ]. In the present study we showed that exogenous NPY enhances autophagy in rat cortical neurons through NPY Y 1 , Y 2 or Y 5 receptor activation.

The similarity between the effects of caloric restriction and NPY on autophagy in cortical neuronal suggests that NPY mediates caloric restriction-induced autophagy and may be considered as a caloric restriction mimetic, as suggested by others [ 29 , 60 ].

NPY and caloric restriction induce similar physiological effects, such as: hyperphagia, decreased blood glucose levels, reduced core body temperature and reduced fertility [ 29 ]. In addition, it has been shown that NPY mediates the antitumorigenic effect of caloric restriction and that caloric restriction does not increase lifespan of NPY KO mice, enlightening NPY role as a lifespan and aging regulator [ 61 , 62 ].

In fact, in humans, increased NPY levels may also be correlated with lifespan benefits, since long-lived female centenarians have higher NPY plasma levels compared to younger women [ 63 ].

Aging is associated with attenuated ghrelin signaling [ 64 , 65 ]. During aging, caloric restriction produces health benefits accompanied by enhanced ghrelin and ghrelin receptor GHS-R1a levels [ 41 - 43 , 66 - 68 ].

For the first time, we show that ghrelin levels rise in rat cortical neurons upon caloric restriction, and blocking ghrelin receptor GHS-R1a , the stimulatory effect of caloric restriction on autophagy was partially inhibited. These results suggest that ghrelin signaling may represent one of the mechanisms activated by caloric restriction.

Moreover, similarly to caloric restriction, exogenous ghrelin stimulates autophagy in rat cortical neurons, by GHS-R1a receptor activation. These results suggest the potential role of ghrelin as a caloric restriction mimetic. In fact, like caloric restriction, ghrelin has several beneficial effects of age-related diseases.

Ghrelin is involved in the regulation of cardiovascular functions increase of cardiac output, decrease blood flow, protection against cardiac damage, anti-apoptotic effects , bone metabolism increase osteoblast differentiation and bone mineral density and inflammation suppressing the production of cytokines [ 48 ].

Ghrelin is also involved in memory and learning and has a neuroprotective effect in neurodegenerative diseases and ischemic brain injury models [ 46 , 48 , 69 ]. Indeed, ghrelin is effective in improving cell survival, reducing infarct size and rescuing memory in these animal models.

Although it has been proposed that dysfunction of ghrelin signaling, through GHS-R1a ablation, may be beneficial to age-related obesity and insulin resistance [ 70 ], it has been reported that ghrelin administration in rodents and humans can possibly reverse certain characteristics of aging [ 71 - 78 ].

In fact, a recent study shows that increasing ghrelin signalling ameliorated several age-related disorders and prolonged survival in several animal models of human aging, supporting endogenous ghrelin signalling as an important role in preventing aging-related diseases and premature death [ 78 ].

Ghrelin and GHS-R1a functions are diverse and the inter-action between their central and peripheral effects are complex, raising some controversy regarding ghrelin physiological versus pharmacological action [ 79 ]. The effectiveness of ghrelin in these roles may be impaired as ghrelin levels decrease with age, perhaps contributing to other age-related conditions like insulin resistance and diabetes, reduced fertility, and decreased performance on cognitive and memory tasks with advancing age [ 80 , 81 ].

In addition, ghrelin is already being used in several clinical trials as a therapeutic strategy for the treatment of cachexia in chronic heart failure, cancer, end stage- renal disease or cystic fibrosis, frailty in elderly, anorexia nervosa, growth hormone deficient patients and sleep-wake regulation e.

major depression [ 82 , 83 ]. The significant overlap between caloric restriction- and ghrelin-induced physiological processes suggest that ghrelin may play a role in the beneficial effects of caloric restriction on health and lifespan.

In fact, we observed that ghrelin increases NPY expression in rat cortical neurons and NPY Y 1 , Y 2 or Y 5 subtypes receptors antagonists inhibited the stimulatory effect of ghrelin on autophagy.

These observations suggest that, similarly to caloric restriction, NPY also mediates ghrelin-induced autophagy in rat cortical neurons. The contribution of NPY in ghrelin effects has been shown by other on feeding behavior, energy balance, growth hormone secretion and gastrointestinal motility [ 45 , 57 , 84 - 87 ].

Cellular metabolic stress underpins the development of pathological conditions, of which the prevalence increases dramatically with age.

Aurophagy more information about Caloric restriction and autophagy markers Subject Areas, Citrus aurantium metabolism here. Studies have demonstrated that resveratrol caliric natural polyphenol and caloric restriction caloric restriction and autophagy markers Sirtuin-1 SIRT1 and mrakers autophagy. Restrictioj, autophagy caloric restriction and autophagy markers induced by caloeic SIRT1-FoxO signaling pathway and was recently shown to be a critical protective mechanism against non-alcoholic fatty liver disease NAFLD development. We aimed to compare the effects of resveratrol and caloric restriction on hepatic lipid metabolism and elucidate the mechanism by which resveratrol supplementation and caloric restriction alleviate hepatosteatosis by examining the molecular interplay between SIRT1 and autophagy. The groups were maintained for 18 weeks. Loss of skeletal Smart mealtime planning mass and function is a hallmark of restrition. This phenomenon has been related to a dysregulation of mitochondrial function sutophagy proteostasis. Calorie Energy-boosting shots Restrictioj Energy-boosting shots been caloric restriction and autophagy markers to delay aging and preserve function until late in life, particularly in muscle. In these conditions, lard fed mice showed an increased longevity compared to mice fed soybean or fish oils. We focus our discussion on dietary fatty acid saturation degree as an essential predictor of life span extension in CR mice. Many UC-authored scholarly publications are freely available on this site because of the UC's open access policies.