Proteomics-based identification of different training adaptations of aged skeletal muscle following long-term high-intensity interval and moderate-intensity continuous training in aged rats

High intensity interval training alters linear gait parameters associated with muscle fiber morphometry regardless of age and diet in rats

Most research involving rodents has analyzed biomechanical gait parameters under pathological conditions, with some studies exploring the effects of moderate-intensity training on these variables in the context of aging and disease. Additionally, aging and obesity in humans cause morphological changes in the musculoskeletal system, while physical exercise helps mitigate muscle deterioration. This study aimed to investigate linear gait kinematics and muscle tissue morphometry in Wistar rats of different ages, fed a high-fat diet (HFD), and subjected to a HIIT protocol. Thus, the aim of this study was to analyze linear kinematic gait parameters, as well as morphometric aspects of muscle tissue in Wistar rats of different ages fed with an HFD diet and subjected to a high-intensity interval training (HIIT) protocol. Seven-, nine-, 12- and 18-month-old male Wistar rats divided in 16 groups (n = 7): T-SD and S-SD (trained and sedentary fed with standard diet), S-HFD and T-HFD (trained and sedentary fed with high-fat diet) were subjected to a HIIT protocol, 3x a week, for 8 weeks. After the training period, the gait cycles of all groups were recorded. The cross-sectional area of the muscle fibers of the soleus and extensor digitorum longus was assessed. The practice of HIIT body mass and causing muscle fiber hypertrophy regardless of diet and age (p < 0.001), increased maximum running capacity, reduced stride length, stride and support time, and increased stride frequency, even under the influence of age (p < 0.001). As a conclusion, HIIT promoted greater linear locomotor efficiency, resulting in a more efficient and dynamic gait. Obesity condition did not directly affect the linear variables analyzed.

Bioinformatics Analysis Identifies Key Genes in the Effect of Resistance Training on Female Skeletal Muscle Aging

Resistance training is used to combat skeletal muscle function decline in older adults. Few studies have been designed specific for females, resulting in very limited treatment options for skeletal muscle atrophy in aging women. Here, we analyzed the gene expression profiles of skeletal muscle samples from sedentary young women, sedentary older women, and resistance-trained older women, using microarray data from public database. A total of 45 genes that were differentially expressed during female muscle aging and reversed by resistance training were identified. Functional and pathway enrichment analysis, protein-protein interaction network analysis, and receiver operating characteristic analysis were performed to reveal the key genes and pathways involved in the effects of resistance training on female muscle aging. The collagen genes COL1A1, COL3A1, and COL4A1 were identified important regulators of female muscle aging and resistance training, by modulating multiple signaling pathways, such as PI3 kinase-Akt signaling, focal adhesions, extracellular matrix-receptor interactions, and relaxin signaling. Interestingly, the expression of CDKN1A and TP63 were increased during aging, and further upregulated by resistance training in older women, suggesting they may negatively affect resistance training outcomes. Our findings provide novel insights into the molecular mechanisms of resistance training on female muscle aging and identify potential biomarkers and targets for clinical intervention.

Proteomic reference map for sarcopenia research: mass spectrometric identification of key muscle proteins of organelles, cellular signaling, bioenergetic metabolism and molecular chaperoning

During the natural aging process, frailty is often associated with abnormal muscular performance. Although inter-individual differences exit, in most elderly the tissue mass and physiological functionality of voluntary muscles drastically decreases. In order to study age-related contractile decline, animal model research is of central importance in the field of biogerontology. Here we have analyzed wild type mouse muscle to establish a proteomic map of crude tissue extracts. Proteomics is an advanced and large-scale biochemical method that attempts to identify all accessible proteins in a given biological sample. It is a technology-driven approach that uses mass spectrometry for the characterization of individual protein species. Total protein extracts were used in this study in order to minimize the potential introduction of artefacts due to excess subcellular fractionation procedures. In this report, the proteomic survey of aged muscles has focused on organellar marker proteins, as well as proteins that are involved in cellular signaling, the regulation of ion homeostasis, bioenergetic metabolism and molecular chaperoning. Hence, this study has establish a proteomic reference map of a highly suitable model system for future aging research.

Aged gastrocnemius muscle of mice positively responds to a late onset adapted physical training

Introduction: A regular physical training is known to contribute to preserve muscle mass and strength, maintaining structure and function of neural and vascular compartments and preventing muscle insulin resistance and inflammation. However, physical activity is progressively reduced during aging causing mobility limitations and poor quality of life. Although physical exercise for rehabilitation purposes (e.g., after fractures or cardiovascular events) or simply aiming to counteract the development of sarcopenia is frequently advised by physicians, nevertheless few data are available on the targets and the global effects on the muscle organ of adapted exercise especially if started at old age. Methods: To contribute answering this question for medical translational purposes, the proteomic profile of the gastrocnemius muscle was analyzed in 24-month-old mice undergoing adapted physical training on a treadmill for 12 weeks or kept under a sedentary lifestyle condition. Proteomic data were implemented by morphological and morphometrical ultrastructural evaluations. Results and Discussion: Data demonstrate that muscles can respond to adapted physical training started at old age, positively modulating their morphology and the proteomic profile fostering protective and saving mechanisms either involving the extracellular compartment as well as muscle cell components and pathways (i.e., mitochondrial processes, cytoplasmic translation pathways, chaperone-dependent protein refolding, regulation of skeletal muscle contraction). Therefore, this study provides important insights on the targets of adapted physical training, which can be regarded as suitable benchmarks for future in vivo studies further exploring the effects of this type of physical activity by functional/metabolic approaches.

Advances in exercise to alleviate sarcopenia in older adults by improving mitochondrial dysfunction

Sarcopenia is a chronic degenerative disease affecting primarily older adults. A growing aging population is gradually increasing the number of patients suffering from sarcopenia, placing increasing financial pressure on patients' families and society in general. There is a strong link between mitochondrial dysfunction and sarcopenia pathogenesis. As a result, treating sarcopenia by improving mitochondrial dysfunction is an effective strategy. Numerous studies have demonstrated that exercise has a positive effect on mitochondrial dysfunction when treating sarcopenia. Exercise promotes mitochondrial biogenesis and mitochondrial fusion/division to add new mitochondria or improve dysfunctional mitochondria while maintaining mitochondrial calcium homeostasis, mitochondrial antioxidant defense system, and mitochondrial autophagy to promote normal mitochondrial function. Furthermore, exercise can reduce mitochondrial damage caused by aging by inhibiting mitochondrial oxidative stress, mitochondrial DNA damage, and mitochondrial apoptosis. Exercise effectiveness depends on several factors, including exercise duration, exercise intensity, and exercise form. Therefore, Moderate-intensity exercise over 4 weeks potentially mitigates sarcopenia in older adults by ameliorating mitochondrial dysfunction. HIIT has demonstrated potential as a viable approach to addressing sarcopenia in aged rats. However, further investigation is required to validate its efficacy in treating sarcopenia in older adults.

High intensity interval training attenuates osteoarthritis-associated hyperalgesia in rats

High-intensity interval training (HIIT) is a physical therapy that may benefit patients with osteoarthritis (OA). Cacna2d1 is a calcium channel subunit protein that plays an important role in the activity of nerve cells. However, there is currently no evidence on HIIT relieving OA-associate hyperalgesia by decreased Cacna2d1. Our study established the OA rat models with intra-articular injection of monosodium iodoacetate (MIA). This experiment was divided into two stages. The first stage comprised three groups: the control, OA, and OA-HIIT groups. The second stage comprised two groups, including the AAV-C and AAV-shRNA-Cacna2d1 groups. OA rats were positioned at the L5-L6 segments, and 20 µl of AAV virus was injected intrathecally. The pain threshold, cartilage analysis, Cacna2d1, and pain neurotransmitters were measured and compared. The pain threshold was significantly lower in OA rats than in control rats from the first to the tenth week. Starting from the sixth week, OA-HIIT rats exhibited significantly increased pain thresholds. The expression of Cacna2d1 increased in OA rats. Moreover, the knockdown of Cacna2d1 significantly down-regulated the expression of c-Fos, SP, and Vglut2 in the posterior horn of the spinal cord. In conclusion, HIIT attenuates OA-associated hyperalgesia, which may be related to the down-regulation of Cacna2d1.

Indirect regulation of HIPPO pathway by miRNA mediates high-intensity intermittent exercise to ameliorate aging skeletal muscle function

Exercise-induced microRNA (miRNA) and HIPPO pathways participate in the regulation of skeletal muscle plasticity but their underlying mechanisms remain unclear. We aimed to investigate the effect of high-intensity interval training (HIIT) on miRNA expression and the HIPPO pathway in the skeletal muscle of aging rats to determine its role in the amelioration of muscle aging. Thirty-six 18-month-old female rats were randomly divided into sedentary control (SED, n = 12), moderate-intensity continuous training (MICT, n = 12), and HIIT (n = 12) groups, with continuous exercise for 8 months. Quantitative reverse transcription-polymerase chain reaction, immunoblotting, KEGG enrichment, and dual-luciferase assays were performed on the target skeletal muscle. Compared with the SED group, the MICT and HIIT groups showed a significant trend of improvement in Lee's index and grip strength and a marked increase in skeletal muscle mitochondrial function, apoptosis, antioxidant, and lipolysis-related protein expression. They also exhibited PI3K/AKT pathway activation and a decrease in expression of HIPPO pathway-related proteins; 20 miRNAs were differentially expressed and enriched in the exercise group compared with the SED group, including the HIPPO pathway and metabolic pathways. Further analysis of L6 cells confirmed that miR-182 may target PTEN, which indirectly regulates HIPPO signaling, but not Mob1. the combined application of HIIT and MICT increased the antioxidant and lipolytic capacities of skeletal muscle and improved atrophy of aging skeletal muscle; HIIT was more effective than MICT. This may be related to HIIT-mediated AKT pathway activation and HIPPO pathway inhibition by miRNAs (miR-486 and miR-182).

Fiber-Type Shifting in Sarcopenia of Old Age: Proteomic Profiling of the Contractile Apparatus of Skeletal Muscles

The progressive loss of skeletal muscle mass and concomitant reduction in contractile strength plays a central role in frailty syndrome. Age-related neuronal impairments are closely associated with sarcopenia in the elderly, which is characterized by severe muscular atrophy that can considerably lessen the overall quality of life at old age. Mass-spectrometry-based proteomic surveys of senescent human skeletal muscles, as well as animal models of sarcopenia, have decisively improved our understanding of the molecular and cellular consequences of muscular atrophy and associated fiber-type shifting during aging. This review outlines the mass spectrometric identification of proteome-wide changes in atrophying skeletal muscles, with a focus on contractile proteins as potential markers of changes in fiber-type distribution patterns. The observed trend of fast-to-slow transitions in individual human skeletal muscles during the aging process is most likely linked to a preferential susceptibility of fast-twitching muscle fibers to muscular atrophy. Studies with senescent animal models, including mostly aged rodent skeletal muscles, have confirmed fiber-type shifting. The proteomic analysis of fast versus slow isoforms of key contractile proteins, such as myosin heavy chains, myosin light chains, actins, troponins and tropomyosins, suggests them as suitable bioanalytical tools of fiber-type transitions during aging.

High Intensity Interval Training: A Potential Method for Treating Sarcopenia

Sarcopenia, an age-related disease characterized by loss of muscle strength and muscle mass, has attracted the attention of medical experts due to its severe morbidity, low living quality, high expenditure of health care, and mortality. Traditionally, persistent aerobic exercise (PAE) is considered as a valid way to attenuate muscular atrophy. However, nowadays, high intensity interval training (HIIT) has emerged as a more effective and time-efficient method to replace traditional exercise modes. HIIT displays comprehensive effects on exercise capacity and skeletal muscle metabolism, and it provides a time-out for the recovery of cardiopulmonary and muscular functions without causing severe adverse effects. Studies demonstrated that compared with PAE, HIIT showed similar or even higher effects in improving muscle strength, enhancing physical performances and increasing muscle mass of elder people. Therefore, HIIT might become a promising way to cope with the age-related loss of muscle mass and muscle function. However, it is worth mentioning that no study of HIIT was conducted directly on sarcopenia patients, which is attributed to the suspicious of safety and validity. In this review, we will assess the effects of different training parameters on muscle and sarcopenia, summarize previous papers which compared the effects of HIIT and PAE in improving muscle quality and function, and evaluate the potential of HIIT to replace the status of PAE in treating old people with muscle atrophy and low modality; and point out drawbacks of temporary experiments. Our aim is to discuss the feasibility of HIIT to treat sarcopenia and provide a reference for clinical scientists who want to utilize HIIT as a new way to cope with sarcopenia.

Effect of 32-Weeks High-Intensity Interval Training and Resistance Training on Delaying Sarcopenia: Focus on Endogenous Apoptosis

Sarcopenia caused by aging is an important factor leading to a decline in the quality of life of older people. Apoptosis in muscle atrophy accelerates the process of muscle loss in older populations. The present study aimed to investigate the effects of 32 weeks of high-intensity interval training (HIIT) and resistance training (RT) on the skeletal muscle-related indices and provide a theoretical basis for regulating the mitochondrial-mediated pathway to delay sarcopenia. We randomly selected 10 from eight-month-old male SD rats (N = 130) as the baseline group; after 1 week of adaptive feeding, the rats were sacrificed. The remaining rats were randomly assigned to one of three groups: control group (C, N = 40, natural aging for 32 weeks), HIIT group (H, N = 40, performed six loops of 3 min at 90% and 3 min at 50% VO2 max speed treadmill running, with 5 min at 70% VO2 max speed at the beginning and the end of the training, 3 times a week for 32 weeks), and resistance group (R, n = 40, 46 min per day, 3 days per week, with a 30% maximum load on a treadmill with a slope of 35°, 15 m/min). The soleus muscles were collected for analysis at baseline and every 8 weeks. Aging resulted in decreased soleus muscle mass and Bcl-2 levels in the mitochondria, while the levels of reactive oxygen species (ROS) and Bax did not change. HIIT reversed the age-associated activation of pro-apoptotic processes, but RT did not. In addition, when rats were aged from 8 to 16 months, the level of Cyt-C did not change, the Caspase-9 levels and Caspase-3 levels decreased gradually in the soleus muscles, the rats of both the HIIT and RT groups had these indices decreased at 32 weeks. The results suggest that the age-associated loss of muscle mass was reversed by training, and the effect of RT was better than that of HIIT. Both the HIIT and RT rats showed a decrease in the apoptosis of skeletal muscle cells after 32 weeks of intervention. HIIT performed better for long-term intervention regarding the pro-apoptotic factors. This study warranted further research to delineate the underlying mechanism of effects of different exercise methods on the changes of aging skeletal muscle at in vivo level.

Multi-omics research in sarcopenia: Current progress and future prospects

Sarcopenia is a systemic disease with progressive and generalized skeletal muscle dysfunction defined by age-related low muscle mass, high content of muscle slow fibers, and low muscle function. Muscle phenotypes and sarcopenia risk are heritable; however, the genetic architecture and molecular mechanisms underlying sarcopenia remain largely unclear. In recent years, significant progress has been made in determining susceptibility loci using genome-wide association studies. In addition, recent advances in omics techniques, including genomics, epigenomics, transcriptomics, proteomics, and metabolomics, offer new opportunities to identify novel targets to help us understand the pathophysiology of sarcopenia. However, each individual technology cannot capture the entire view of the biological complexity of this disorder, while integrative multi-omics analyses may be able to reveal new insights. Here, we review the latest findings of multi-omics studies for sarcopenia and provide an in-depth summary of our current understanding of sarcopenia pathogenesis. Leveraging multi-omics data could give us a holistic understanding of sarcopenia etiology that may lead to new clinical applications. This review offers guidance and recommendations for fundamental research, innovative perspectives, and preventative and therapeutic interventions for sarcopenia.

Effects of high-intensity interval training on mitochondrial supercomplex assembly and biogenesis, mitophagy, and the AMP-activated protein kinase pathway in the soleus muscle of aged female rats

PURPOSE

Exercise helps improve mitochondrial function to combat sarcopenia. Certain parts of the mitochondrial respiratory chain complex can form a higher-order structure called "supercomplex" to reduce the production of reactive oxygen species and improve muscle mass. The effect of exercise on the assembly of the mitochondrial supercomplex is still unclear. The aim of this study was to investigate the effects of long-term high-intensity interval training (HIIT) on mitochondrial biogenesis, mitophagy, and mitochondrial supercomplexes (mitoSCs) assembly in aging soleus muscle.

METHODS

Female Sprague-Dawley rats (n = 36) were randomly divided into four groups: young sedentary (Y-SED, 8 months old, n = 12), old sedentary (O-SED, 26 months old, n = 12), moderate-intensity continuous training (MICT, from 18 to 26 months old, n = 12), and HIIT (from 18 to 26 months old, n = 12). Rats in the MICT and HIIT groups were subjected to an 8-month training program. Real-time fluorescent quantitative polymerase chain reaction was used to measure the expression of the antioxidative factors, inflammatory factors, and mitochondrial fusion- and division-related genes. Western blotting was used to detect the expression of mitochondrial biogenesis and mitophagy markers and AMP-activated protein kinase (AMPK) pathway proteins. Enzyme-linked immunosorbent assays were used to determine serum irisin contents. Blue native polyacrylamide gel electrophoresis was used to assess the formation of mitochondrial supercomplexes.

RESULTS

Compared with the Y-SED group, the soleus muscle and mitochondria in the O-SED group showed reduced expression of mitophagy- and mitochondrial biogenesis-related proteins. In the HIIT group, the expression of autophagy-related proteins in the soleus muscle and mitochondria was significantly increased compared with that in the MICT group. Serum irisin and mitochondrial fusion protein levels significantly decreased with age. Superoxide dismutase 2 protein levels and AMPK pathway protein expression were significantly increased in the HIIT group compared with those in the other groups. Additionally, the expression levels of mitoSCs and the mRNA levels of interleukin-15 and optical atrophy 1 increased in the HIIT group compared with that in the MICT group.

CONCLUSION

Compared with MICT, HIIT activated the AMPK pathway to upregulate mitochondrial biogenesis- and mitophagy-related proteins, and promote the assembly and formation of mitoSCs to improve the mitochondrial function of aging soleus muscles.

Bibliometric Review to Explore Emerging High-Intensity Interval Training in Health Promotion: A New Century Picture

Background: High-intensity interval training (HIIT) is an emerging exercise strategy and is considered to be a recipe for health promotion. This study aimed to systematically identify collaboration networks, track research trends, highlight current hotspots, and predict future frontiers in HIIT and its applications in health promotion since the start of the new century. Methods: Relevant original publications were obtained from the Science Citation Index Expanded of the Web of Science Core Collection (WoSCC) database between 2001 and 2020. CiteSpace and VOSviewer software were used to perform bibliometric visualization and comparative analysis of involved indexes that included countries, institutions, journals, authors, references, and keywords. Results: A total of 572 papers were included, and the trend of annual publications showed a remarkable growth. The United States and the University of Exeter were the most productive country and institutions, respectively, with 107 and 18 publications, respectively. European Journal of Applied Physiology took the lead in the number of published articles, and Medicine and Science in Sports and Exercise ranked first in the cocitation counts. Barker AR and Gibala MJ were considered as the most productive and the most highly-cited authors. Conclusions: "Health risks," "adolescent," and "aging" are the three noteworthy topics during the evolution of HIIT-health promotion (HIIT-HP) research. The current research hotspots of HIIT and its practices in the health promotion domain lies in "metabolic diseases," "cardiovascular diseases," "neurological diseases," and "musculoskeletal diseases." The authors summarize that "prevention and rehabilitation," "micro and molecular level," and "cognition and mental health" are becoming frontiers and focus on the health topics related to HIIT in the upcoming years, which are worthy of further exploration.

Impact of high-intensity interval training on cardiorespiratory fitness, body composition, physical fitness, and metabolic parameters in older adults: A meta-analysis of randomized controlled trials

High-intensity interval training (HIIT) can effectively increase peak oxygen consumption, body composition, physical fitness, and health-related characteristics of adults; however, its impact in the older population remains highly debated. This review and meta-analysis aimed to evaluate the effects of high-intensity interval training on cardiorespiratory fitness, body composition, physical fitness, and health-related outcomes in older adults. Four electronic databases (PubMed, Scopus, Medline, and Web of Science) were searched (until July 2020) for randomized trials comparing the effect of HIIT on physical fitness, metabolic parameters, and cardiorespiratory fitness in older adults. The Cochrane risk of bias assessment tool was used to evaluate the methodological quality of the included studies; Stata 14.0 software was used for statistical analysis. HIIT significantly improved the maximum rate of oxygen consumption (VO_2peak) as compared to a moderate-intensity continuous training (MICT) protocol (HIIT vs. MICT: weighted mean difference = 1.74, 95% confidence interval: 0.80-2.69, p < 0.001). Additional subgroup analyses determined that training periods >12 weeks, training frequencies of 2 sessions/week, session lengths of 40 min, 6 sets and repetitions, training times per repetition of >60 s, and rest times of <90 s were more effective for VO_2peak. This systematic review and meta-analysis showed that HIIT induces favorable adaptions in cardiorespiratory fitness, physical fitness, muscle power, cardiac contractile function, mitochondrial citrate synthase activity, and reduced blood triglyceride and glucose levels in older individuals, which may help to maintain aerobic fitness and slow down the process of sarcopenia.

Key Signaling Pathways in Aging and Potential Interventions for Healthy Aging

Aging is a fundamental biological process accompanied by a general decline in tissue function. Indeed, as the lifespan increases, age-related dysfunction, such as cognitive impairment or dementia, will become a growing public health issue. Aging is also a great risk factor for many age-related diseases. Nowadays, people want not only to live longer but also healthier. Therefore, there is a critical need in understanding the underlying cellular and molecular mechanisms regulating aging that will allow us to modify the aging process for healthy aging and alleviate age-related disease. Here, we reviewed the recent breakthroughs in the mechanistic understanding of biological aging, focusing on the adenosine monophosphate-activated kinase (AMPK), Sirtuin 1 (SIRT1) and mammalian target of rapamycin (mTOR) pathways, which are currently considered critical for aging. We also discussed how these proteins and pathways may potentially interact with each other to regulate aging. We further described how the knowledge of these pathways may lead to new interventions for antiaging and against age-related disease.

Effects of lifelong exercise on age-related body composition, oxidative stress, inflammatory cytokines, and skeletal muscle proteome in rats

PURPOSE

This study aims to evaluate whether regular lifelong exercise has effects on age-related inflammatory cytokines, oxidative stress, and the skeletal muscle proteome.

METHODS

Four groups of adult-aged (8-month-old) female Sprague Dawley rats were used: rats for which training was initiated at either 8 (8 M-MICT, moderate-intensity continuous training) or 18 months (18 M-MICT) and sedentary rats aged either 26 (26 M-SED) or 8 months (8M-SED), who served as aging and adult sedentary controls, respectively. Aged skeletal muscles were subjected to proteomic and Kyoto Encyclopedia of Genes and Genomes (KEGG) and immunoblotting analyses.

RESULTS

Age-related loss of physical performance and anti-inflammatory steroid levels were lowest in the 8 M-MICT group, while the anti-oxidative activities remained unchanged compared to 18 M-MICT rats. The proteomic analysis demonstrated an amelioration of age-related changes to muscle contraction, focal adhesion signaling, mitochondrial function, apoptosis and regeneration, anti-oxidation, and protein processing in the endoplasmic reticulum in the 8 M-MICT. Additionally, neurotrophin (BDNF) and AKT/FOXO signaling pathways were upregulated in 8 M-MICT rats compared to 26 M-SED.

CONCLUSION

8 M-MICT exhibited greater beneficial effects in ameliorating age-related inflammation and physical performance loss, compared to 18 M-MICT. The amelioration is potentially related to the upregulation of autophagy activities via BDNF/AKT signaling.

Proteomic profiling analysis of postmenopausal osteoporosis and osteopenia identifies potential proteins associated with low bone mineral density

Postmenopausal osteoporosis (PMOP) is a major global public health concern and older women are more susceptible to experiencing fragility fractures. Our study investigated the associations between circulating proteins with bone mineral density (BMD) in postmenopausal women with or without low BMD (osteoporosis and osteopenia) using a tandem mass tag (TMT) labeling proteomic experiment and parallel reaction monitoring testing. Across all plasma samples, we quantitatively measured 1,092 proteins, and the OP and normal control (NC) samples were differentiated by principal component analysis and a partial least squares-discrimination analysis model based on the protein profiling data. The differentially abundant proteins between the low BMD and NC samples mostly exhibited binding, molecular function regulator, transporter and molecular transducer activity, and were involved in metabolic and cellular processes, stimulus response, biological regulation, immune system processes and so forth. TMT analysis and RRM validation indicated that the expression of protein Lysozyme C (P61626) was negatively related to BMD, while the expression of proteins Glucosidase (A0A024R592) and Protein disulfideisomerase A5 (Q14554) was positively related to BMD values. Collectively, our results suggest that postmenopausal women with low BMD have a different proteomic profile or signature. Protein alterations may play an important role in the pathogenesis of PMOP, and they may act as novel biomarkers and targets of therapeutic agents for this disease.

Exercise, redox system and neurodegenerative diseases

Regular exercise induces a wide range of redox system-associated molecular adaptive responses to the nervous system. The intermittent induction of reactive oxygen species (ROS) during acute exercise sessions and the related upregulation of antioxidant/repair and housekeeping systems are associated with improved physiological function. Exercise-induced proliferation and differentiation of neuronal stem cells are ROS dependent processes. The increased production of brain derived neurotrophic factor (BDNF) and the regulation by regular exercise are dependent upon redox sensitive pathways. ROS are causative and associative factors of neurodegenerative diseases and regular exercise provides significant neuroprotective effects against Alzheimer's disease, Parkinson's disease, and hypoxia/reperfusion related disorders. Regular exercise regulates redox homeostasis in the brain with complex multi-level molecular pathways.