Short term exercise induces PGC-1α, ameliorates inflammation and increases mitochondrial membrane proteins but fails to increase respiratory enzymes in aging diabetic hearts

L-Ergothioneine slows the progression of age-related hearing loss in CBA/CaJ mice

The naturally occurring amino acid, l-ergothioneine (EGT), has immense potential as a therapeutic, having shown promise in the treatment of other disease models, including neurological disorders. EGT is naturally uptaken into cells via its specific receptor, OCTN1, to be utilized by cells as an antioxidant and anti-inflammatory. In our current study, EGT was administered over a period of 6 months to 25-26-month-old CBA/CaJ mice as a possible treatment for age-related hearing loss (ARHL), since presbycusis has been linked to higher levels of cochlear oxidative stress, apoptosis, and chronic inflammation. Results from the current study indicate that EGT can prevent aging declines of some key features of ARHL. However, we found a distinct sex difference for the response to the treatments, for hearing - Auditory Brainstem Responses (ABRs) and Distortion Product Otoacoustic Emissions (DPOAEs). Males exhibited lower threshold declines in both low dose (LD) and high dose (HD) test groups throughout the testing period and did not display some of the characteristic aging declines in hearing seen in Control animals. In contrast, female mice did not show any therapeutic effects with either treatment dose. Further confirming this sex difference, EGT levels in whole blood sampling throughout the testing period showed greater uptake of EGT in males compared to females. Additionally, RT-PCR results from three tissue types of the inner ear confirmed EGT activity in the cochlea in both males and females. Males and females exhibited significant differences in biomarkers related to apoptosis (Cas-3), inflammation (TNF-a), oxidative stress (SOD2), and mitochondrial health (PGC1a).These changes were more prominent in males as compared to females, especially in stria vascularis tissue. Taken together, these findings suggest that EGT has the potential to be a naturally derived therapeutic for slowing down the progression of ARHL, and possibly other neurodegenerative diseases. EGT, while effective in the treatment of some features of presbycusis in aging males, could also be modified into a general prophylaxis for other age-related disorders where treatment protocols would include eating a larger proportion of EGT-rich foods or supplements. Lastly, the sex difference discovered here, needs further investigation to see if therapeutic conditions can be developed where aging females show better responsiveness to EGT.

Physical activity and the heart: from well-established cardiovascular benefits to possible adverse effects

The favorable effects of physical activity on the cardiovascular system have been well described in scientific literature. Physical activity reduces cardiovascular morbidity and mortality in both healthy subjects and in patients with cardiovascular disease. However, different intensity levels of physical activity have a different impact on the cardiovascular system. Some data support the hypothesis of a "physical activity paradox": repetitive exposure to vigorous physical activity may induce biological effects that counteract the benefits of moderate intensity levels of physical activity. In this review, we report the main effects of acute and chronic physical activity on the cardiovascular system and we summarize the biochemical mechanisms that may explain these effects.

Potential Role of the mTORC1-PGC1α-PPARα Axis under Type-II Diabetes and Hypertension in the Human Heart

Type-2 diabetes (T2DM) and arterial hypertension (HTN) are major risk factors for heart failure. Importantly, these pathologies could induce synergetic alterations in the heart, and the discovery of key common molecular signaling may suggest new targets for therapy. Intraoperative cardiac biopsies were obtained from patients with coronary heart disease and preserved systolic function, with or without HTN and/or T2DM, who underwent coronary artery bypass grafting (CABG). Control (n = 5), HTN (n = 7), and HTN + T2DM (n = 7) samples were analysed by proteomics and bioinformatics. Additionally, cultured rat cardiomyocytes were used for the analysis (protein level and activation, mRNA expression, and bioenergetic performance) of key molecular mediators under stimulation of main components of HTN and T2DM (high glucose and/or fatty acids and angiotensin-II). As results, in cardiac biopsies, we found significant alterations of 677 proteins and after filtering for non-cardiac factors, 529 and 41 were changed in HTN-T2DM and in HTN subjects, respectively, against the control. Interestingly, 81% of proteins in HTN-T2DM were distinct from HTN, while 95% from HTN were common with HTN-T2DM. In addition, 78 factors were differentially expressed in HTN-T2DM against HTN, predominantly downregulated proteins of mitochondrial respiration and lipid oxidation. Bioinformatic analyses suggested the implication of mTOR signaling and reduction of AMPK and PPARα activation, and regulation of PGC1α, fatty acid oxidation, and oxidative phosphorylation. In cultured cardiomyocytes, an excess of the palmitate activated mTORC1 complex and subsequent attenuation of PGC1α-PPARα transcription of β-oxidation and mitochondrial electron chain factors affect mitochondrial/glycolytic ATP synthesis. Silencing of PGC1α further reduced total ATP and both mitochondrial and glycolytic ATP. Thus, the coexistence of HTN and T2DM induced higher alterations in cardiac proteins than HTN. HTN-T2DM subjects exhibited a marked downregulation of mitochondrial respiration and lipid metabolism and the mTORC1-PGC1α-PPARα axis might account as a target for therapeutical strategies.

Pleiotropic and multi-systemic actions of physical exercise on PGC-1α signaling during the aging process

Physical training is a potent therapeutic approach for improving mitochondrial health through peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α) signaling pathways. However, comprehensive information regarding the physical training impact on PGC-1α in the different physiological systems with advancing age is not fully understood. This review sheds light on the frontier-of-knowledge data regarding the chronic effects of exercise on the PGC-1α signaling pathways in rodents and humans. We address the molecular mechanisms involved in the different tissues, clarifying the precise biological action of PGC-1α, restricted to the aged cell type. Distinct exercise protocols (short and long-term) and modalities (aerobic and resistance exercise) increase the transcriptional and translational PGC-1α levels in adipose tissue, brain, heart, liver, and skeletal muscle in animal models, suggesting that this versatile molecule induces pleiotropic responses. However, PGC-1α function in some human tissues (adipose tissue, heart, and brain) remains challenging for further investigations. PGC-1α is not a simple transcriptional coactivator but supports a biochemical environment of mitochondrial dynamics, controlling physiological processes (primary metabolism, tissue remodeling, autophagy, inflammation, and redox balance). Acting as an adaptive mechanism, the long-term effects of PGC-1α following exercise may reflect the energy demand to coordinate multiple organs and contribute to cellular longevity.

Effects of the anti-inflammatory drug celecoxib on cell death signaling in human colon cancer

The anti-inflammatory drug celecoxib, the only inhibitor of cyclooxygenase-2 (COX-2) with anticancer activity, is used to treat rheumatoid arthritis and can cause endoplasmic reticulum (ER) stress by inhibiting sarco/ER Ca^{2 +}-ATPase activity in cancer cells. This study aimed to investigate the correlation between celecoxib-induced ER stress and the effects of celecoxib against cell death signaling. Treatment of human colon cancer HCT116 cells with celecoxib reduced their viability and resulted in a loss of mitochondrial membrane potential ([Formula: see text]). Additionally, celecoxib treatment reduced the expression of genes involved in mitochondrial biogenesis and metabolism such as mitochondrial transcription factor A (TFAM) and uncoupling protein 2 (UCP2). Furthermore, celecoxib reduced transmembrane protein 117 (TMEM117), and RNAi-mediated knockdown of TMEM117 reduced TFAM and UCP2 expressions. These results suggest that celecoxib treatment results in the loss of [Formula: see text] by reducing TMEM117 expression and provide insights for the development of novel drugs through TMEM117 expression.

Beyond cardiomyocytes: Cellular diversity in the heart's response to exercise

Cardiomyocytes comprise ∼70% to 85% of the total volume of the adult mammalian heart but only about 25% to 35% of its total number of cells. Advances in single cell and single nuclei RNA sequencing have greatly facilitated investigation into and increased appreciation of the potential functions of non-cardiomyocytes in the heart. While much of this work has focused on the relationship between non-cardiomyocytes, disease, and the heart's response to pathological stress, it will also be important to understand the roles that these cells play in the healthy heart, cardiac homeostasis, and the response to physiological stress such as exercise. The present review summarizes recent research highlighting dynamic changes in non-cardiomyocytes in response to the physiological stress of exercise. Of particular interest are changes in fibrotic pathways, the cardiac vasculature, and immune or inflammatory cells. In many instances, limited data are available about how specific lineages change in response to exercise or whether the changes observed are functionally important, underscoring the need for further research.

Molecular mechanisms underlying the beneficial effects of exercise and dietary interventions in the prevention of cardiometabolic diseases

Cardiometabolic diseases still represent a major cause of mortality worldwide. In addition to pharmacological approaches, lifestyle interventions can also be adopted for the prevention of these morbid conditions. Lifestyle changes include exercise and dietary restriction protocols, such as calorie restriction and intermittent fasting, which were shown to delay cardiovascular ageing and elicit health-promoting effects in preclinical models of cardiometabolic diseases. Beneficial effects are mediated by the restoration of multiple molecular mechanisms in heart and vessels that are compromised by metabolic stress. Exercise and dietary restriction rescue mitochondrial dysfunction, oxidative stress and inflammation. They also improve autophagy. The result of these effects is a marked improvement of vascular and heart function. In this review, we provide a comprehensive overview of the molecular mechanisms involved in the beneficial effects of exercise and dietary restriction in models of diabetes and obesity. We also discuss clinical studies and gap in animal-to-human translation.

An overview of the molecular and physiological antidepressant mechanisms of physical exercise in animal models of depression

BACKGROUND

Depression is a global disease that affects the physical and mental health of people of all ages. Non-pharmacological and unconventional methods of treatment, such as regular physical exercise, have been recommended to treat depression.

METHODS

Here, we briefly review the literature about the physiological and molecular mechanisms of exercise antidepressants in depressive-like behavior in animal models of depression.

RESULTS

The main hysiological and molecular mechanisms of physical exercise in depression include blood flow changes in several areas of the brain, increase in brain serotonin synthesis, increase in antioxidant enzymes, increase in serum and brain brain-derived neuro factor (BDNF) levels, decrease in cortisol levels and reduced inflammation in peripheral and brain tissues. Physical exercise also leads to increased activation of the phosphatidylinositol-3-kinase (PI3K), PGC-1α/FNDC5/Irisin pathway, BDNF concentrations (serum and cerebral), extracellular signal-regulated kinase and cAMP-response element binding protein (mainly in neurons of the hippocampus and prefrontal cortex), which together contribute to fight or inhibit the development of depression symptoms. These molecular and physiological mechanisms work in synchrony, further enhancing their effects.

CONCLUSION

Physical exercise can be used as a safe and effective non-pharmacological treatment in depression.

Syringic Acid Attenuates Cardiomyopathy in Streptozotocin-Induced Diabetic Rats

Objectives

Diabetic cardiomyopathy (DC) has become one of the serious complications in diabetic cases. In this study, we aimed to explore the syringic acid (SYR) protective effect against diabetes-induced cardiac injury in experimental rats.

Methods

Rats were divided in control and streptozotocin-induced diabetic rats which were subdivided into diabetic controls, and three test groups (SYR at 25, 50, and 100 mg/kg) and the nondiabetic group received 100 mg/kg of SYR. All treatments were given SYR for 6 weeks. SYR effects on cardiac diagnostic markers, heart lipid peroxidation, protein carbonylation, antioxidant system, and changes of the heart mitochondrial mass and biogenesis were measured.

Results

Diabetes induction prompted CK-MB, LDH levels in serum, cardiac catalase, and superoxide dismutase activity, as well as cardiac TBARs and carbonylated protein. SYR administration (100 m/kg) attenuated CK-MB and LDH levels. Also, 50 and 100 mg/kg of SYR reduced cardiac TBARs and carbonylated protein in diabetic rats. These treatments did not show any effects on GSH content, mtDNA, and mitochondrial biogenesis indices (PGC1- α, NRF1, NRF2, and TFAM) in heart tissue.

Conclusions

SYR treatment showed protective effects on diabetic cardiomyopathy in rats by reducing lipid peroxidation and protein carbonylation. The possible mechanisms could be related to antioxidant activity of this phenolic acid. SYR might play a role of a protective factor in cardiac challenges in diabetes.

The Effect of Gembili Starch (Dioscorea esculenta) and Eubacterium rectal Supplementation on Skeletal Muscle Peroxisome Proliferator-Activated Receptor γ Coactivator 1α (Pgc-1α) Expression in Diabetic Mice Models

BACKGROUND: Gembili or Dioscorea esculenta is a local food that is produced by several areas in Indonesia. Few studies have reported its health benefits for diabetes mellitus but a little is understood about its mechanism of action. PGC-1α is a transcriptional coactivator for genes that involved in energy metabolism and increased expression of this gene has previously been associated with improved insulin sensitivity. AIM: The objective of this study was to investigate the effect of Gembili starch and Gembili starch with butirogenic bacteria Eubacterium rectal on PGC-1α expression in skeletal muscle of diabetic mice. MATERIALS AND METHODS: Three months old male diabetic Wistar mice were divided into groups based on dietary supplement: Gembili starch only; Gembili starch with E. rectal; and E. rectal only. Positive (diabetic mice) and negative (non-diabetic) control groups were used in this study. After 4 weeks of supplementation, mice were sacrificed and muscle tissue was taken from musculus vastus latissimus. Plasma blood glucose was measured before and after intervention. PGC-1α expression was measured with immunohistochemistry and quantified by dividing cells that produce PGC-1α with total cells. RESULTS: Plasma blood glucose was reduced after invention in group that received Gembili starch only (p < 0.001); Gembili starch with E. rectal (p < 0.001); and E. rectal only (p < 0.001). The protein expression of PGC-1α in diabetic mice receiving Gembili starch only was significantly higher compared to control (p < 0.05). CONCLUSION: This study shown that Gembili starch supplementation was able to improve glucose control in diabetic mice and this effect was obtained perhaps through PGC-1α activation. Further study is needed to investigate the effect of Gembili starch supplementation on fat metabolism.

Moderate Intensity Aerobic Exercise Potential Favorable Effect Against COVID-19: The Role of Renin-Angiotensin System and Immunomodulatory Effects

The coronavirus disease (COVID-19) pandemic is caused by a novel coronavirus (CoV) named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). As the angiotensin converting enzyme 2 (ACE2) is the cellular receptor of SARS-CoV-2, it has a strong interaction with the renin angiotensin system (RAS). Experimental studies have shown that the higher levels of ACE2 or increasing ACE2/ACE1 ratio improve COVID-19 outcomes through lowering inflammation and death. Aerobic moderate intensity physical exercise fights off infections by two mechanisms, the inhibition of ACE/Ang II/AT1-R pathway and the stimulation of ACE2/Ang-(1-7)/MasR axis. Exercise can also activate the anti-inflammatory response so that it can be a potential therapeutic strategy against COVID-19. Here, we summarize and focus the relation among COVID-19, RAS, and immune system and describe the potential effect of aerobic moderate intensity physical exercise against CoV as a useful complementary tool for providing immune protection against SARS-CoV-2 virus infection, which is a novel intervention that requires further investigation.

Role of the Mitochondrial Protein Import Machinery and Protein Processing in Heart Disease

Mitochondria are essential organelles for cellular energy production, metabolic homeostasis, calcium homeostasis, cell proliferation, and apoptosis. About 99% of mammalian mitochondrial proteins are encoded by the nuclear genome, synthesized as precursors in the cytosol, and imported into mitochondria by mitochondrial protein import machinery. Mitochondrial protein import systems function not only as independent units for protein translocation, but also are deeply integrated into a functional network of mitochondrial bioenergetics, protein quality control, mitochondrial dynamics and morphology, and interaction with other organelles. Mitochondrial protein import deficiency is linked to various diseases, including cardiovascular disease. In this review, we describe an emerging class of protein or genetic variations of components of the mitochondrial import machinery involved in heart disease. The major protein import pathways, including the presequence pathway (TIM23 pathway), the carrier pathway (TIM22 pathway), and the mitochondrial intermembrane space import and assembly machinery, related translocases, proteinases, and chaperones, are discussed here. This review highlights the importance of mitochondrial import machinery in heart disease, which deserves considerable attention, and further studies are urgently needed. Ultimately, this knowledge may be critical for the development of therapeutic strategies in heart disease.

Effects of physical exercise on memory in type 2 diabetes: a brief review

Type 2 diabetes (T2D) is a metabolic disorder that can lead to memory impairment. T2D main features are insulin resistance and hyperglycemia. Physical exercise is a non-pharmacological intervention that can regulate glycemic levels and fight insulin resistance in T2D, but whether it influences memory has been discussed. There are 2 main types of physical exercise: aerobic exercise and resistance exercise. Here, we review about the consequences of different physical exercise protocols on memory in diabetic subjects and animal models of T2D. Physical exercise, aerobic or resistance training, most of the times, is a capable agent to prevent and treat memory loss on diabetic subjects and animal models of T2D. However, whether aerobic and resistance training combined improve memory in subjects with T2D remains controversial. Regarding animal models of T2D, aerobic and resistance training have been showed to be capable to prevent and treat memory loss. Acute and chronic protocols of exercise, generally, induce positive physiological responses and adaptations in T2D, such as a better glucose control. The ideal physical exercise protocol that will produce the best benefits to diabetic subjects and to animal models of T2D has not been described yet. A variety of combination between intensity, volume, frequency, and duration of the physical exercise protocol on future studies is necessary to both diabetic subjects and animal models of T2D to determine the best protocol that will induce more benefits on memory in T2D.

Exercise Effects On Cardiovascular Disease: From Basic Aspects To Clinical Evidence

Cardiovascular (CV) disease (CVD) remains the leading cause of major morbidity and CVD- and all-cause mortality in most of the world. It is now clear that regular physical activity (PA) and exercise training (ET) induces a wide range of direct and indirect physiologic adaptations and pleiotropic benefits for human general and CV health. Generally, higher levels of PA, ET, and cardiorespiratory fitness (CRF) are correlated with reduced risk of CVD, including myocardial infarction, CVD-related death, and all-cause mortality. Although exact details regarding the ideal doses of ET, including resistance and, especially, aerobic ET, as well as the potential adverse effects of extreme levels of ET, continue to be investigated, there is no question that most of the world's population have insufficient levels of PA/ET, and many also have lower than ideal levels of CRF. Therefore, assessment and promotion of PA, ET, and efforts to improve levels of CRF should be integrated into all health professionals' practices worldwide. In this state-of-the-art review, we discuss the exercise effects on many areas related to CVD, from basic aspects to clinical practice.

Differentiation of THP-1 monocytes to macrophages increased mitochondrial DNA copy number but did not increase expression of mitochondrial respiratory proteins or mitochondrial transcription factor A

Monocytes are differentiated into macrophages. In this study, mitochondrial DNA copy number (mtDNAcn) levels and downstream events such as the expression of respiratory chain mRNAs were investigated during the phorbol 12-myristate 13-acetate (PMA)-induced differentiation of monocytes. Although PMA treatment increased mtDNAcn, the expression levels of mRNAs encoded in mtDNA were decreased. The levels of mitochondrial transcription factor A mRNA and protein were also decreased. The levels of coenzyme Q10 remained unchanged. These results imply that, although mtDNAcn is considered as a health marker, the levels of mtDNAcn may not always be consistent with the parameters of mitochondrial functions.

Physical exercise effects on the brain during COVID-19 pandemic: links between mental and cardiovascular health

The current pandemic was caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The quarantine period during corona virus disease 19 (COVID-19) outbreak might affect the quality of life leading thousands of individuals to diminish the daily caloric expenditure and mobility, leading to a sedentary behavior and increase the number of health disorders. Exercising is used as a non-pharmacological treatment in many chronic diseases. Here, we review the molecular mechanisms of physical exercise in COVID-19 pandemic on mental health. We also point links between exercise, mental, and cardiovascular health. The infection caused by SARS-CoV-2 affects host cells binding to angiotensin-converting enzyme-2 (ACE2), which is the receptor for SARS-CoV-2. If there is not enough oxygen supply the lungs and other tissues, such as the heart or brain, are affected. SARS-CoV-2 enhances ACE2 leading to inflammation and neuronal death with possible development of mood disorders, such as depression and anxiety. Physical exercise also enhances the ACE2 expression. Conversely, the activation of ACE2/Ang 1-7/Mas axis by physical exercise induces an antiinflammatory and antifibrotic effect. Physical exercise has beneficial effects on mental health enhancing IGF-1, PI3K, BDNF, ERK, and reducing GSK3β levels. In addition, physical exercise enhances the activity of PGC-1α/ FNDC5/Irisin pathway leading to neuronal survival and the maintenance of a good mental health. Thus, SARS-CoV-2 infection leads to elevation of ACE2 levels through pathological mechanisms that lead to neurological and cardiovascular complications, while the physiological response of ACE2 to physical exercise improves cardiovascular and mental health.

Exercise-Linked Irisin: Consequences on Mental and Cardiovascular Health in Type 2 Diabetes

Type 2 diabetes mellitus (T2DM) is a metabolic disorder associated with insulin resistance and hyperglycemia. Chronic exposure to a T2DM microenvironment with hyperglycemia, hyperinsulinemia, oxidative stress and increased levels of proinflammatory mediators, has negative consequences to the cardiovascular system and mental health. Therefore, atherosclerotic cardiovascular diseases (CVD) and mental health issues have been strongly associated with T2DM. Lifestyle modifications, including physical exercise training, are necessary to prevent T2DM development and its associated complications. It is widely known that the regular practice of exercise provides several physiological benefits to subjects with T2DM, such as managing glycemic and blood pressure levels. Different types of exercise, from aerobic to resistance training, are effective to improve mental health and cognitive function in T2DM. Irisin is a myokine produced in response to exercise, which has been pointed as a relevant mechanism of action to explain the benefits of exercise on cardiovascular and mental health in T2DM patients. Here, we review emerging clinical and experimental evidence about exercise-linked irisin consequences to cardiovascular and mental health in T2DM.

Exercise and cardiac health: physiological and molecular insights

The cardiac benefits of exercise have been recognized for centuries. Studies have undisputedly shown that regular exercise is beneficial for the cardiovascular system in young, old, healthy and diseased populations. For these reasons, physical activity has been recommended worldwide for cardiovascular disease prevention and treatment. Although the benefits of exercise are clear, understanding of the molecular triggers that orchestrate these effects remains incomplete and has been a topic of intense research in recent years. Here, we provide a comprehensive review of the cardiac effects of physical activity, beginning with a brief history of exercise in cardiovascular medicine and then discussing seminal work on the physiological effects of exercise in healthy, diseased and aged hearts. Later, we revisit pioneering work on the molecular mechanisms underlying the cardiac benefits of exercise, and we conclude with our view on the translational potential of this knowledge as a powerful platform for cardiovascular disease drug discovery.

Basic Mechanisms of Diabetic Heart Disease

Diabetes mellitus predisposes affected individuals to a significant spectrum of cardiovascular complications, one of the most debilitating in terms of prognosis is heart failure. Indeed, the increasing global prevalence of diabetes mellitus and an aging population has given rise to an epidemic of diabetes mellitus-induced heart failure. Despite the significant research attention this phenomenon, termed diabetic cardiomyopathy, has received over several decades, understanding of the full spectrum of potential contributing mechanisms, and their relative contribution to this heart failure phenotype in the specific context of diabetes mellitus, has not yet been fully resolved. Key recent preclinical discoveries that comprise the current state-of-the-art understanding of the basic mechanisms of the complex phenotype, that is, the diabetic heart, form the basis of this review. Abnormalities in each of cardiac metabolism, physiological and pathophysiological signaling, and the mitochondrial compartment, in addition to oxidative stress, inflammation, myocardial cell death pathways, and neurohumoral mechanisms, are addressed. Further, the interactions between each of these contributing mechanisms and how they align to the functional, morphological, and structural impairments that characterize the diabetic heart are considered in light of the clinical context: from the disease burden, its current management in the clinic, and where the knowledge gaps remain. The need for continued interrogation of these mechanisms (both known and those yet to be identified) is essential to not only decipher the how and why of diabetes mellitus-induced heart failure but also to facilitate improved inroads into the clinical management of this pervasive clinical challenge.

Altered mitochondrial metabolism in the insulin-resistant heart

Obesity-induced insulin resistance and type 2 diabetes mellitus can ultimately result in various complications, including diabetic cardiomyopathy. In this case, cardiac dysfunction is characterized by metabolic disturbances such as impaired glucose oxidation and an increased reliance on fatty acid (FA) oxidation. Mitochondrial dysfunction has often been associated with the altered metabolic function in the diabetic heart, and may result from FA-induced lipotoxicity and uncoupling of oxidative phosphorylation. In this review, we address the metabolic changes in the diabetic heart, focusing on the loss of metabolic flexibility and cardiac mitochondrial function. We consider the alterations observed in mitochondrial substrate utilization, bioenergetics and dynamics, and highlight new areas of research which may improve our understanding of the cause and effect of cardiac mitochondrial dysfunction in diabetes. Finally, we explore how lifestyle (nutrition and exercise) and pharmacological interventions can prevent and treat metabolic and mitochondrial dysfunction in diabetes.

Egg white consumption increases GSH and lowers oxidative damage in 110-week-old geriatric mice hearts

The number of geriatrics with an advanced age is rising worldwide, with attendant cardiovascular disorders, characterized by elevated oxidative stress. Such oxidative stress is accelerated by an age-related loss of critical antioxidants like glutathione (GSH) and dietary solutions to combat this loss does not exist. While egg white is rich in sulphur amino acids (AAs), precursors for GSH biosynthesis, whether they can increase sulphur AA in vivo and augment GSH in the aged myocardium remain unclear. We hypothesized that egg white consumption increases GSH and reduces oxidative damage and inflammation in the geriatric heart. To this end, 101-102 week-old mice were given a AIN 76A diet supplemented with either 9% w/w egg white powder or casein for 8 weeks. Subsequent analysis revealed that egg white increased serum sulphur AA and cardiac GSH, while reducing the cysteine carrying transporter SNAT-2 and elevating glutamine transporter ASCT2 in the heart. Increased GSH was accompanied by elevated expression of GSH biosynthesis enzyme glutathione synthase as well as mitochondrial antioxidants like superoxide dismutase 2 and glutathione peroxidase 1 in egg white-fed hearts. These hearts also demonstrated lower oxidative damage of lipids (4-hydroxynonenal) and proteins [nitrotyrosine] with elevated anti-inflammatory IL-10 gene expression. These data demonstrate that even at the end of lifespan, egg whites remain effective in promoting serum sulphur AAs and preserve cardiac GSH with potent anti-oxidant and mild anti-inflammatory effects in the geriatric myocardium. We conclude that egg white intake may be an effective dietary strategy to attenuate oxidative damage in the senescent heart.

The Non-cardiomyocyte Cells of the Heart. Their Possible Roles in Exercise-Induced Cardiac Regeneration and Remodeling

The non-cardiomyocyte cellular microenvironment of the heart includes diverse types of cells of mesenchymal origin. During development, the majority of these cells derive from the epicardium, while a subset derives from the endothelium/endocardium and neural crest derived mesenchyme. This subset includes cardiac fibroblasts and telocytes, the latter of which are a controversial type of "connecting cell" that support resident cardiac progenitors in the postnatal heart. Smooth muscle cells, pericytes, and endothelial cells are also present, in addition to adipocytes, which accumulate as epicardial adipose connective tissue. Furthermore, the heart harbors many cells of hematopoietic origin, such as mast cells, macrophages, and other immune cell populations. Most of these control immune reactions and inflammation. All of the above-mentioned non-cardiomyocyte cells of the heart contribute to this organ's well-orchestrated physiology. These cells also contribute to regeneration as a result of injury or age, in addition to tissue remodeling triggered by chronic disease or increased physical activity (exercise-induced cardiac growth). These processes in the heart, the most important vital organ in the human body, are not only fascinating from a scientific standpoint, but they are also clinically important. It is well-known that regular exercise can help prevent many cardiovascular diseases. However, the precise mechanisms underpinning myocardial remodeling triggered by physical activity are still unknown. Surprisingly, exercise-induced adaptation mechanisms are often identical or very similar to tissue remodeling caused by pathological conditions, such as hypertension, cardiac hypertrophy, and cardiac fibrosis. This review provides a summary of our current knowledge regarding the cardiac cellular microenvironment, focusing on the clinical applications this information to the study of heart remodeling during regular physical exercise.

Roles and Mechanisms of Herbal Medicine for Diabetic Cardiomyopathy: Current Status and Perspective

Diabetic cardiomyopathy is one of the major complications among patients with diabetes mellitus. Diabetic cardiomyopathy (DCM) is featured by left ventricular hypertrophy, myocardial fibrosis, and damaged left ventricular systolic and diastolic functions. The pathophysiological mechanisms include metabolic-altered substrate metabolism, dysfunction of microvascular, renin-angiotensin-aldosterone system (RAAS) activation, oxidative stress, cardiomyocyte apoptosis, mitochondrial dysfunction, and impaired Ca²⁺ handling. An array of molecules and signaling pathways such as p38 mitogen-activated protein kinase (p38 MAPK), c-Jun N-terminal kinase (JNK), and extracellular-regulated protein kinases (ERK) take roles in the pathogenesis of DCM. Currently, there was no remarkable effect in the treatment of DCM with application of single Western medicine. The myocardial protection actions of herbs have been gearing much attention. We present a review of the progress research of herbal medicine as a potential therapy for diabetic cardiomyopathy and the underlying mechanisms.

Liraglutide alleviates H2O2-induced retinal ganglion cells injury by inhibiting autophagy through mitochondrial pathways

Retinal ganglion cells (RGCs), which exist in the inner retina, are the retinal neurons which can be damaged in the early stage of diabetic retinopathy (DR). Liraglutide, a glucagon-like peptide-1 (GLP-1) analog, exerts biological functions by binding the receptor (GLP-1R), the expression of which in RGC-5 cells was first shown by our team in 2012. It was reported that liraglutide prevented retinal neurodegeneration in diabetic subjects. However, the involvement of mechanisms such as autophagy and mitochondrial balance in liraglutide-induced retinal protection is unknown. Here, we aimed to investigate the protective effects of liraglutide and explore the potential mechanisms of liraglutide-induced retinal RGC protection. RGC-5 cells were treated with H₂O₂ and/or liraglutide. Cell viability was detected with the CCK-8 kit. The axon marker GAP43, autophagy and mitophagy indicators LC3A/B, Beclin-1, p62, Parkin, BCL2/Adenovirus E1B 19kDa protein-interacting protein 3-like (BNIP3L) and the key regulator of mitochondrial biogenesis PGC-1α were examined via western blot analysis. Autophagy was also evaluated using the ImageXpress Micro XLS system and transmission electron microscopy (TEM). Reactive oxygen species (ROS), mitochondrial membrane potential and fluorescent staining for mitochondria were also measured using the ImageXpress Micro XLS system. Our results showed that pretreatment with liraglutide significantly prevented H₂O₂-induced cell viability decline, mitochondrial morphological deterioration and induction of autophagy, which appeared as increased expression of LC3 II/I and Beclin-1, along with p62 degradation. Moreover, liraglutide suppressed the H₂O₂-induced decline in GAP43 expression, thus protecting cells. However, rapamycin induced autophagy and blocked the protective process. Liraglutide also provided mitochondrial protection and appeared to alleviate H₂O₂-induced ROS overproduction and a decline in mitochondrial membrane potential, partially by promoting mitochondrial generation and attenuating mitophagy. In conclusion, liraglutide attenuates H₂O₂ induced RGC-5 cell injury by inhibiting autophagy through maintaining a balance between mitochondrial biogenesis and mitophagy.

Incretin hormones regulate microglia oxidative stress, survival and expression of trophic factors

The incretin hormones glucagon-like peptide (GLP)-1 and glucose-dependent insulinotropic polypeptide (GIP) are primarily known for their metabolic function in the periphery. GLP-1 and GIP are secreted by intestinal endocrine cells in response to ingested nutrients. Both GLP-1 and GIP stimulate the production and release of insulin from pancreatic β cells as well as exhibit several growth-regulating effects on peripheral tissues. GLP-1 and GIP are also present in the brain, where they provide modulatory and anti-apoptotic signals to neurons. However, very limited information is available regarding the effects of these hormones on glia, the immune and supporting cells of the brain. Therefore, we set out to resolve whether primary human microglia and astrocytes, two subtypes of glial cells, express the GLP-1 receptor (GLP-1R) and GIP receptor (GIPR), which are necessary to detect and respond to GLP-1 and GIP, respectively. We further tested whether these hormones, similar to their effects on neuronal cells, have growth-regulating, antioxidant and anti-apoptotic effects on microglia. We show for the first time expression of the GLP-1R and the GIPR by primary human microglia and astrocytes. We demonstrate that GLP-1 and GIP reduce apoptotic death of murine BV-2 microglia through the binding and activation of the GLP-1R and GIPR, respectively, with subsequent activation of the protein kinase A (PKA) pathway. Moreover, we reveal that incretins upregulate BV-2 microglia expression of brain derived neurotrophic factor (BDNF), glial cell-line derived neurotrophic factor (GDNF) and nerve growth factor (NGF) in a phosphoinositide 3-kinase (PI3K)- and PKA-dependent manner. We also show that incretins reduce oxidative stress in BV-2 microglia by inhibiting the accumulation of intracellular reactive oxygen species (ROS) and release of nitric oxide (NO), as well as by increasing the expression of the antioxidant glutathione peroxidase 1 (GPx1) and superoxide dismutase 1 (SOD1). We confirm these results by demonstrating that GLP-1 and GIP also inhibit apoptosis of primary murine microglia, and upregulate expression of BDNF by primary murine microglia. These results indicate that GLP-1 and GIP affect several critical homeostatic functions of microglia, and could therefore be tested as a novel therapeutic treatment option for brain disorders that are characterized by increased oxidative stress and microglial degeneration.

Assessed and Emerging Biomarkers in Stroke and Training-Mediated Stroke Recovery: State of the Art

Since the increasing update of the biomolecular scientific literature, biomarkers in stroke have reached an outstanding and remarkable revision in the very recent years. Besides the diagnostic and prognostic role of some inflammatory markers, many further molecules and biological factors have been added to the list, including tissue derived cytokines, growth factor-like molecules, hormones, and microRNAs. The literatures on brain derived growth factor and other neuroimmune mediators, bone-skeletal muscle biomarkers, cellular and immunity biomarkers, and the role of microRNAs in stroke recovery were reviewed. To date, biomarkers represent a possible challenge in the diagnostic and prognostic evaluation of stroke onset, pathogenesis, and recovery. Many molecules are still under investigation and may become promising and encouraging biomarkers. Experimental and clinical research should increase this list and promote new discoveries in this field, to improve stroke diagnosis and treatment.

A 3-methylcrotonyl-CoA carboxylase deficient human skin fibroblast transcriptome reveals underlying mitochondrial dysfunction and oxidative stress

Isolated 3-methylcrotonyl-CoA carboxylase (MCC) deficiency is an autosomal recessive inherited metabolic disease of leucine catabolism with a highly variable phenotype. Apart from extensive mutation analyses of the MCCC1 and MCCC2 genes encoding 3-methylcrotonyl-CoA carboxylase (EC 6.4.1.4), molecular data on MCC deficiency gene expression studies in human tissues is lacking. For IEMs, unbiased '-omics' approaches are starting to reveal the secondary cellular responses to defects in biochemical pathways. Here we present the first whole genome expression profile of immortalized cultured skin fibroblast cells of two clinically affected MCC deficient patients and two healthy individuals generated using Affymetrix(®)HuExST1.0 arrays. There were 16191 significantly differentially expressed transcript IDs of which 3591 were well annotated and present in the predefined knowledge database of Ingenuity Pathway Analysis software used for downstream functional analyses. The most noticeable feature of this MCCA deficient skin fibroblast transcriptome was the typical genetic hallmark of mitochondrial dysfunction, decreased antioxidant response and disruption of energy homeostasis, which was confirmed by mitochondrial functional analyses. The MCC deficient transcriptome seems to predict oxidative stress that could alter the complex secondary cellular response that involve genes of the glycolysis, the TCA cycle, OXPHOS, gluconeogenesis, β-oxidation and the branched-chain fatty acid metabolism. An important emerging insight from this human MCCA transcriptome in combination with previous reports is that chronic exposure to the primary and secondary metabolites of MCC deficiency and the resulting oxidative stress might impact adversely on the quality of life and energy levels, irrespective of whether MCC deficient individuals are clinically affected or asymptomatic.

Suppression of endothelial PGC-1α is associated with hypoxia-induced endothelial dysfunction and provides a new therapeutic target in pulmonary arterial hypertension

Endothelial dysfunction plays a principal role in the pathogenesis of pulmonary arterial hypertension (PAH), which is a fatal disease with limited effective clinical treatments. Mitochondrial dysregulation and oxidative stress are involved in endothelial dysfunction. Peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) is a key regulator of cellular energy metabolism and a master regulator of mitochondrial biogenesis. However, the roles of PGC-1α in hypoxia-induced endothelial dysfunction are not completely understood. We hypothesized that hypoxia reduces PGC-1α expression and leads to endothelial dysfunction in hypoxia-induced PAH. We confirmed that hypoxia has a negative impact on endothelial PGC-1α in experimental PAH in vitro and in vivo. Hypoxia-induced PGC-1α inhibited the oxidative metabolism and mitochondrial function, whereas sustained PGC-1α decreased reactive oxygen species (ROS) formation, mitochondrial swelling, and NF-κB activation and increased ATP formation and endothelial nitric oxide synthase (eNOS) phosphorylation. Furthermore, hypoxia-induced changes in the mean pulmonary arterial pressure and right heart hypertrophy were nearly normal after intervention. These results suggest that PGC-1α is associated with endothelial function in hypoxia-induced PAH and that improved endothelial function is associated with improved cellular mitochondrial respiration, reduced inflammation and oxygen stress, and increased PGC-1α expression. Taken together, these findings indicate that PGC-1α may be a new therapeutic target in PAH.

Elevated Expression of Carboxy-Terminal Modulator Protein (CTMP) Aggravates Brain Ischemic Injury in Diabetic db/db Mice

Deregulation of Akt signaling is important in the brain injuries caused by cerebral ischemia in diabetic animals, and the underlying mechanism is not fully understood. We investigated the role of carboxy-terminal modulator protein (CTMP), an endogenous Akt inhibitor, in brain injury following focal cerebral ischemia in type 2 diabetic db/db mice and their control littermates non-diabetic db/+ mice. db/db mice showed a significant elevation in the expression of CTMP compared to db/+ mice under normal physiological conditions. After ischemia, db/db mice exhibit higher levels of CTMP expression, decreased Akt kinase activity, adverse neurological deficits and cerebral infarction than db/+ mice. To further certain the effectiveness of Akt signaling to the final outcome of cerebral ischemia, the animals were treated with LY294002, an inhibitor of the Akt pathway, which aggravated the ischemic injury in db/+ mice but not in db/db mice. RNA interference-mediated depletion of CTMP were finally applied in db/db mice, which restored Akt activity, improved neurological scores and reduced infarct volume. These results suggest that elevation of CTMP in diabetic mice suppresses Akt activity and ultimately negatively affects the outcome of ischemia. Inhibitors specifically targeting CTMP may be beneficial in the treatment of cerebral ischemia in patients with diabetes.

Glutathione administration reduces mitochondrial damage and shifts cell death from necrosis to apoptosis in ageing diabetic mice hearts during exercise

BACKGROUND AND PURPOSE

The effect of antioxidants on ageing type 2 diabetic (T2D) hearts during exercise is unclear. We hypothesized that GSH therapy during exercise reduces mitochondrial oxidative stress (mOXS) and cell death in ageing db/db mice hearts.

EXPERIMENTAL APPROACH

The effect of GSH on cardiac mOXS and cell death was evaluated both in vivo and in vitro.

KEY RESULTS

During exercise, GSH treatment protected db/db hearts from exaggerated mOXS without reducing total cell death. Despite similar cell death, investigations on apoptosis-specific single-stranded DNA breaks and necrosis-specific damage provided the first in vivo evidence of a shift from necrosis to apoptosis, with reduced fibrosis following GSH administration in exercised db/db hearts. Further support for a GSH-regulated 'switch' in death phenotypes came from NIH-3T3 fibroblasts and H9c2 cardiomyocytes treated with H2 O2 , a reactive oxygen species (ROS). Similar to in vivo findings, augmenting GSH by overexpressing glutamyl cysteine ligase (GCLc) protected fibroblasts and cardiomyocytes from necrosis induced by H2 O2 , but elevated caspase-3 and apoptosis instead. Similar to in vivo findings, where GSH therapy in normoglycaemic mice suppressed endogenous antioxidants and augmented caspase-3 activity, GCLc overexpression during staurosporine-induced death, which was not characterized by ROS, increased GSH efflux and aggravated death in fibroblasts and cardiomyocytes, confirming that oxidative stress is required for GSH-mediated cytoprotection.

CONCLUSIONS AND IMPLICATIONS

While GSH treatment is useful for reducing mOXS and attenuating necrosis and fibrosis in ageing T2D hearts during exercise, such antioxidant treatment could be counterproductive in the healthy heart during exercise.

Excess Linoleic Acid Increases Collagen I/III Ratio and "Stiffens" the Heart Muscle Following High Fat Diets

Controversy exists on the benefits versus harms of n-6 polyunsaturated fatty acids (n-6 PUFA). Although n-6 PUFA demonstrates anti-atherosclerotic properties, survival following cardiac remodeling may be compromised. We hypothesized that n-6 PUFA like linoleic acid (LA) or other downstream PUFAs like γ-linolenic acid or arachidonic acid alter the transforming growth factor-β (TGFβ)-collagen axis in the heart. Excess dietary LA increased the collagen I/III ratio in the mouse myocardium, leading to cardiac "stiffening" characterized by impaired transmitral flow indicative of early diastolic dysfunction within 5 weeks. In vitro, LA under TGFβ1 stimulation increased collagen I and lysyl oxidase (LOX), the enzyme that cross-links soluble collagen resulting in deposited collagen. Overexpression of fatty acid desaturase 2 (fads2), which metabolizes LA to downstream PUFAs, reduced collagen deposits, LOX maturation, and activity with LA, whereas overexpressing fads1, unrelated to LA desaturation, did not. Furthermore, fads2 knockdown by RNAi elevated LOX activity and collagen deposits in fibroblasts with LA but not oleic acid, implying a buildup of LA for aggravating such pro-fibrotic effects. As direct incubation with γ-linolenic acid or arachidonic acid also attenuated collagen deposits and LOX activity, we concluded that LA itself, independent of other downstream PUFAs, promotes the pro-fibrotic effects of n-6 PUFA. Overall, these results attempt to reconcile opposing views of n-6 PUFA on the cardiovascular system and present evidence supporting a cardiac muscle-specific effect of n-6 PUFAs. Therefore, aggravation of the collagen I/III ratio and cardiac stiffening by excess n-6 PUFA represent a novel pathway of cardiac lipotoxicity caused by high n-6 PUFA diets.

Exercise Prevention of Cardiovascular Disease in Breast Cancer Survivors

Thanks to increasingly effective treatment, breast cancer mortality rates have significantly declined over the past few decades. Following the increase in life expectancy of women diagnosed with breast cancer, it has been recognized that these women are at an elevated risk for cardiovascular disease due in part to the cardiotoxic side effects of treatment. This paper reviews evidence for the role of exercise in prevention of cardiovascular toxicity associated with chemotherapy used in breast cancer, and in modifying cardiovascular risk factors in breast cancer survivors. There is growing evidence indicating that the primary mechanism for this protective effect appears to be improved antioxidant capacity in the heart and vasculature and subsequent reduction of treatment-related oxidative stress in these structures. Further clinical research is needed to determine whether exercise is a feasible and effective nonpharmacological treatment to reduce cardiovascular morbidity and mortality in breast cancer survivors, to identify the cancer therapies for which it is effective, and to determine the optimal exercise dose. Safe and noninvasive measures that are sensitive to changes in cardiovascular function are required to answer these questions in patient populations. Cardiac strain, endothelial function, and cardiac biomarkers are suggested outcome measures for clinical research in this field.

The Protective Effects of Salidroside from Exhaustive Exercise-Induced Heart Injury by Enhancing the PGC-1 α -NRF1/NRF2 Pathway and Mitochondrial Respiratory Function in Rats

Objective. To test the hypothesis that salidroside (SAL) can protect heart from exhaustive exercise-induced injury by enhancing mitochondrial respiratory function and mitochondrial biogenesis key signaling pathway PGC-1α–NRF1/NRF2 in rats. Methods. Male Sprague-Dawley rats were divided into 4 groups: sedentary (C), exhaustive exercise (EE), low-dose SAL (LS), and high-dose SAL (HS). After one-time exhaustive swimming exercise, we measured the changes in cardiomyocyte ultrastructure and cardiac marker enzymes and mitochondrial electron transport system (ETS) complexes activities in situ. We also measured mitochondrial biogenesis master regulator PGC-1α and its downstream transcription factors, NRF1 and NRF2, expression at gene and protein levels. Results. Compared to C group, the EE group showed marked myocardium ultrastructure injury and decrease of mitochondrial respiratory function (P < 0.05) and protein levels of PGC-1α, NRF1, and NRF2 (P < 0.05) but a significant increase of PGC-1α, NRF1, and NRF2 genes levels (P < 0.05); compared to EE group, SAL ameliorated myocardium injury, increased mitochondrial respiratory function (P < 0.05), and elevated both gene and protein levels of PGC-1α, NRF-1, and NRF-2. Conclusion. Salidroside can protect the heart from exhaustive exercise-induced injury. It might act by improving myocardial mitochondrial respiratory function by stimulating the expression of PGC-1α–NRF1/NRF2 pathway.

How exercise may amend metabolic disturbances in diabetic cardiomyopathy

SIGNIFICANCE

Over-nutrition and sedentary lifestyle has led to a worldwide increase in obesity, insulin resistance, and type 2 diabetes (T2D) associated with an increased risk of development of cardiovascular disorders. Diabetic cardiomyopathy, independent of hypertension or coronary disease, is induced by a range of systemic changes and may through multiple processes result in functional and structural cardiac derangements. The pathogenesis of this cardiomyopathy is complex and multifactorial, and it will eventually lead to reduced cardiac working capacity and increased susceptibility to ischemic injury.

RECENT ADVANCES

Metabolic disturbances such as altered lipid handling and substrate utilization, decreased mechanical efficiency, mitochondrial dysfunction, disturbances in nonoxidative glucose pathways, and increased oxidative stress are hallmarks of diabetic cardiomyopathy. Interestingly, several of these disturbances are found to precede the development of cardiac dysfunction.

CRITICAL ISSUES

Exercise training is effective in the prevention and treatment of obesity and T2D. In addition to its beneficial influence on diabetes/obesity-related systemic changes, it may also amend many of the metabolic disturbances characterizing the diabetic myocardium. These changes are due to both indirect effects, exercise-mediated systemic changes, and direct effects originating from the high contractile activity of the heart during physical training.

FUTURE DIRECTIONS

Revealing the molecular mechanisms behind the beneficial effects of exercise training is of considerable scientific value to generate evidence-based therapy and in the development of new treatment strategies.

Neuroprotection of Early Locomotor Exercise Poststroke: Evidence From Animal Studies

Early locomotor exercise after stroke has attracted a great deal of attention in clinical and animal research in recent years. A series of animal studies showed that early locomotor exercise poststroke could protect against ischemic brain injury and improve functional outcomes through the promotion of angiogenesis, inhibition of acute inflammatory response and neuron apoptosis, and protection of the blood-brain barrier. However, to date, the clinical application of early locomotor exercise poststroke was limited because some clinicians have little confidence in its effectiveness. Here we review the current progress of early locomotor exercise poststroke in animal models. We hope that a comprehensive awareness of the early locomotor exercise poststroke may help to implement early locomotor exercise more appropriately in treatment for ischemic stroke.

The many roles of PGC-1α in muscle--recent developments

Skeletal muscle is the largest organ in the body and contributes to innumerable aspects of organismal biology. Muscle dysfunction engenders numerous diseases, including diabetes, cachexia, and sarcopenia. At the same time, skeletal muscle is also the main engine of exercise, one of the most efficacious interventions for prevention and treatment of a wide variety of diseases. The transcriptional coactivator PGC-1α has emerged as a key driver of metabolic programming in skeletal muscle, both in health and in disease. We review here the many aspects of PGC-1α function in skeletal muscle, with a focus on recent developments.