The effect of exercise, resveratrol or their combination on Sarcopenia in aged rats via regulation of AMPK/Sirt1 pathway

Inhibition of TLR9 attenuates skeletal muscle fibrosis in aged sarcopenic mice via the p53/SIRT1 pathway

Sarcopenia is an age-related syndrome characterized by a gradual loss of muscle mass and function, but its pathophysiological mechanism remains unclear. Skeletal muscle extracellular matrix (ECM) remodeling is an important pathological change in sarcopenia, and fibrosis is the most obvious manifestation of this change. We found that the expression of the immunoreceptor Toll-like receptor 9 (TLR9) is significantly increased in skeletal muscle in aged mice and is positively related to muscle fibrosis. Moreover, in previous reports, the longevity gene Sirt1 was reported to attenuate ECM deposition and improve muscle function. In this study, we hypothesized that TLR9 modulated skeletal muscle fibrosis via Sirt1. We used TLR9 knockout (TLR9 KO) mice and C57 mice, and grip strength and body composition were compared at different ages. We found that TLR9 knockout significantly attenuated skeletal muscle fibrosis and improved muscle function in aged mice. Furthermore, silent information regulator 1 (Sirt1) activity in mice was inhibited by Ex527, which is a specific inhibitor of Sirt1. Negative Sirt1 regulation via the activation of TLR9-related signaling pathways participated in skeletal muscle fibrosis in the sarcopenic mice, and this process might mediated by the Sirt1/Smad signaling pathway. Our findings revealed that fibrosis changes in the gastrocnemius muscle in sarcopenic mice are closely related to TLR9 activation, and TLR9 modulation could be a therapeutic strategy for combating sarcopenia during aging.

Advantages and disadvantages of apoptosis in the aging process

Researchers cannot predict as yet how long a human being can live. Life expectancy has been steadily increasing in the last century, but perhaps not always the quality of life in parallel with it. Future generations will be faced with the problems of an increased life expectancy along with the emergence of new age-related diseases. A deeper understanding of the aging process is crucial to ameliorate, if not to prevent, these projected new old-age diseases. One of the mechanisms responsible for healthy aging is through the effective maintenance of physiological, biochemical, and immunological functions. To carry this out, the organism needs to create new cells to replace old ones and to induce the disappearance of old and damaged cells. Apoptosis is involved in all these processes. However, if apoptosis is dysregulated, premature senescence-associated diseases are likely to appear. In our review, the focus will be on a better understanding of the role of apoptosis in the aging process. These signaling pathways will most assuredly be pharmacologically targeted in antiaging medicine therapies.

Caloric Restriction Mimetics against Age-Associated Disease: Targets, Mechanisms, and Therapeutic Potential

The increase in life expectancy has boosted the incidence of age-related pathologies beyond social and economic sustainability. Consequently, there is an urgent need for interventions that revert or at least prevent the pathogenic age-associated deterioration. The permanent or periodic reduction of calorie intake without malnutrition (caloric restriction and fasting) is the only strategy that reliably extends healthspan in mammals including non-human primates. However, the strict and life-long compliance with these regimens is difficult, which has promoted the emergence of caloric restriction mimetics (CRMs). We define CRMs as compounds that ignite the protective pathways of caloric restriction by promoting autophagy, a cytoplasmic recycling mechanism, via a reduction in protein acetylation. Here, we describe the current knowledge on molecular, cellular, and organismal effects of known and putative CRMs in mice and humans. We anticipate that CRMs will become part of the pharmacological armamentarium against aging and age-related cardiovascular, neurodegenerative, and malignant diseases.

Exercise and resveratrol increase fracture resistance in the 3xTg-AD mouse model of Alzheimer's disease

Background

Alzheimer’s disease (AD) and osteoporosis are progressive diseases that affect the elderly population. Both conditions are associated with fracture risk that is greater than twice that of the healthy population. Resveratrol and exercise are two treatments that have been linked with attenuation of age-related diseases, including the risk of bone fractures. In this study, we test the hypothesis that these treatments improve fracture resistance in a mouse model representative of the AD condition.

Methods

Three-month-old male 3xTg-AD mice were treated for 4 months with resveratrol or exercise or both combined, and compared with wild type mice. Exercise training was performed on a treadmill at 15 m/min for 45 min/day, 5 days/week. Resveratrol was given at 4 g/kg diet in the form of pellets. Three-point bending, cross-sectional geometric, and fluorescence analyses were conducted on tibias and compared by treatment group.

Results

Tibias of 3xTg mice exhibited signs of diminished bone quality and fracture under less force than age-matched wild type mice (P < 0.05). Treatment with both resveratrol and exercise improved indicators of fracture resistance and bone quality in AD mice to levels comparable to that of wild type mice (P < 0.05).

Conclusions

The 3xTg mouse model of AD is at elevated risk for limb bone fracture compared to wild type controls. Treatment with resveratrol, exercise, or both in combination improves fracture resistance and cross-sectional geometric indicators of bone strength.

Changes in Redox Signaling in the Skeletal Muscle with Aging

Reduction in muscle strength with aging is due to both loss of muscle mass (quantity) and intrinsic force production (quality). Along with decreased functional capacity of the muscle, age-related muscle loss is associated with corresponding comorbidities and healthcare costs. Mitochondrial dysfunction and increased oxidative stress are the central driving forces for age-related skeletal muscle abnormalities. The increased oxidative stress in the aged muscle can lead to altered excitation-contraction coupling and calcium homeostasis. Furthermore, apoptosis-mediated fiber loss, atrophy of the remaining fibers, dysfunction of the satellite cells (muscle stem cells), and concomitant impaired muscle regeneration are also the consequences of increased oxidative stress, leading to a decrease in muscle mass, strength, and function of the aged muscle. Here we summarize the possible effects of oxidative stress in the aged muscle and the benefits of physical activity and antioxidant therapy.

Evaluating the muscular strength, functional capacity, and risk of sarcopenia in elderly women who practice Mat Pilates

Abstract Introduction: Despite the importance of appropriate levels of muscular strength to maintain the functional capacity and a healthy life in old age, the current literature still lacks studies that investigate the profile of elderly women who practice Mat Pilates regarding these variables. Objective: This study aimed to analyze muscular strength, functional capacity, and risk of sarcopenia in elderly women who practiced Mat Pilates. Method: This is a cross-sectional study carried out with 50 elderly women who practice Mat Pilates in the city of Maringá, Paraná. Sociodemographic and health questionnaires were used, in addition to tests created by a Latin American development group for maturity called Grupo de Desenvolvimento Latino Americano para a Maturidade (GDLAM), sitting-rising test, arm curl test, and SARC-F questionnaire. For data analysis, Shapiro-Wilk and Mann-Whitney U tests, as well as Spearman’s Rank Correlation Coefficients, were used. The level of significance was p < 0.05. Results: The 70-79-year-old elderly women showed worse results in the functional capacity and muscular strength tests of the upper limbs and a higher risk of sarcopenia than the individuals who were under 70 years of age. Muscular strength was inversely related to the reduction of the risk of sarcopenia, and functional capacity was directly associated with this risk. Conclusion: A good functional capacity seems to be related to the reduction of the risk of sarcopenia. Age seems to be an intervening factor for reducing muscular strength levels and functional capacity and increasing the risk of sarcopenia.

Irreversible plasma and muscle protein oxidation and physical exercise

The imbalance between the reactive oxygen (ROS) and nitrogen (RNS) species production and their handling by the antioxidant machinery (low molecular weight antioxidant molecules and antioxidant enzymes), also known as oxidative stress, is a condition caused by physiological and pathological processes. Moreover, oxidative stress may be due to an overproduction of free radicals during physical exercise. Excess of radical species leads to the modification of molecules, such as proteins - the most susceptible to oxidative modification - lipids and DNA. With regard to the oxidation of proteins, carbonylation is an oxidative modification that has been widely described. Several studies have detected changes in the total amount of protein carbonyls following different types of physical exercise, but only few of these identified the specific amino acidic residues targets of such oxidation. In this respect, proteomic approaches allow to identify the proteins susceptible to carbonylation and in many cases, it is also possible to identify the specific protein carbonylation sites. This review focuses on the role of protein oxidation, and specifically carbonyl formation, for plasma and skeletal muscle proteins, following different types of physical exercise performed at different intensities. Furthermore, we focused on the proteomic strategies used to identify the specific protein targets of carbonylation. Overall, our analysis suggests that regular physical activity promotes a protection against protein carbonylation, due to the activation of the antioxidant defence or of the turnover of protein carbonyls. However, we can conclude that from the comprehensive bibliography analysed, there is no clearly defined specific physiological role about this post-translational modification of proteins.

Role of miRNAs in skeletal muscle aging

Purpose

The aim of this study was to explore the role of miRNAs in the process of skeletal muscle aging.

Materials and methods

We analyzed the miRNA microarray datasets from 19 young and 17 old skeletal muscle samples by bioinformatic analysis. Differentially expressed miRNAs were identified, followed by function and pathway enrichment analysis. The expression of miRNAs were validated by real-time quantitative PCR (RT-qPCR) analysis.

Results

A total of 23 miRNAs were found to be differentially expressed in old muscle samples based on two platforms. Gene targets of upregulated miRNAs were significantly enriched in the oxytocin signaling pathway, AMP-activated protein kinase (AMPK) signaling pathway, and Notch signaling pathway. The target genes of downregulated miRNAs were significantly related to gap junction, salivary secretion, and estrogen signaling pathway. has-miR-19a and hsa-miR-34a were significant nodes in the miRNA regulatory network. has-miR-19a was closely related to the AMPK signaling pathway. hsa-miR-34a was closely related to cellular senescence and mitogen-activated protein kinase (MAPK) signaling pathway. PCR analysis showed that the expression of has-miR-34a-5p and has-miR-449b-5p was significantly higher in the patient group than in the control group, while no significant difference was observed in the expression of has-miR-19a-3p and has-miR-144-3p between the two groups. Furthermore, the expression of key target genes involved in cellular senescence (sirtuin 1 [SITRI]), MAPK signaling pathway (vascular endothelial growth factor A [VEGFA]), and AMPK signaling pathway (protein kinase AMP-activated catalytic subunit alpha 1 [PRKAA1] and 6-phosphofructo-2-kinase/fructose-2-,6-biphosphatase 3 [PFKFB3]) were significantly increased in patients with sarcopenia.

Conclusion

has-miR-19a and hsa-miR-34a may play regulatory roles in the aging process of skeletal muscles and may be candidate targets to prevent muscle aging. Further experimental validations are warranted.

Effects of resveratrol, exercises and their combination on Farnesoid X receptor, Liver X receptor and Sirtuin 1 gene expression and apoptosis in the liver of elderly rats with nonalcoholic fatty liver

Background

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disorder. This study aims to consider effects of resveratrol, exercise and their combination on Farnesoid X receptor (Fxr), the liver X receptor (Lxr) and Sirtuin 1 (Sirt 1) genes expression in the liver of elderly rats with NAFLD.

Methods

Rats with NAFLD were randomly divided into seven groups including patient, saline, resveratrol (RSV), interval exercise, continuous exercise, interval exercise + RSV and continuous exercise + RSV. Levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP) in the liver tissue were measured using specific ELISA kits. A TUNEL assay kit was used for the assessment of hepatic cells apoptosis. Lipid profiles were considered by measuring the serum triglyceride, cholesterol, LDL, and HDL. Expression of Sirt1, Lxr and Fxr genes was considered using RT-PCR.

Results

Resveratrol administration alone or combined with exercise training significantly improved the expression of Sirt1, Lxr and Fxr genes (p < 0.05) in the hepatic tissue of rats with NAFLD, while levels of AST, ALT, ALP enzymes, as well as apoptotic cells were significantly decreased (p < 0.05).

Discussion

Although resveratrol alone improves the expression of Sirt1, Lxr and Fxr, as well as liver function, combined therapy with exercise training is more effective to improve NAFLD.

Integrated study on comparative transcriptome and skeletal muscle function in aged rats

The present study aimed to reveal aging-related changes in the skeletal muscle of SD rats by comparing transcriptome analysis, integrated with muscle physiological parameters. Ten rats aged 25 months were set as the old group (OG) and ten rats aged 6 months were set as the young group (YG). After 6 weeks of feeding, the body mass, grip strength, and gastrocnemius muscle mass were determined, and the differentially expressed genes were analyzed by transcriptome sequencing, followed by GO enrichment analysis and KEGG analysis. The results showed that the muscle index and the relative grip strength were lower in OG rats than YG rats. The expressions of AMPK, UCP3, IGF-1, several ion channel associated genes and collagen family genes were down-regulated in OG rats. MGMT, one of the strength determining genes and CHRNa1, a subunit of the acetylcholine receptor were up-regulated in OG rats. The present results supply the global transcriptomic information involved in aging related skeletal muscle dysfunction in rats. The reduced expressions of AMPK, IGF-1, and CASK can explain the losses of muscle mass and function in the aged rats. In addition, the up-regulation of MGMT and CHRNa1 also contribute to muscle wasting and weakness during aging.