Improvement of Cardiac Function in Rats With Myocardial Infarction by Low-Intensity to Moderate-Intensity Endurance Exercise Is Associated With Normalization of Klotho and SIRT1

Therapeutic applications of exercise in neurodegenerative diseases: focusing on the mechanism of SIRT1

Neurodegenerative diseases comprise a group of central nervous system disorders marked by progressive neuronal degeneration and dysfunction. Their pathogenesis is multifactorial, involving oxidative stress, mitochondrial dysfunction, excitotoxicity, and neuroinflammation. Recent research has highlighted the potential of exercise as a non-pharmacological intervention for both the prevention and treatment of these disorders. In particular, exercise has received growing attention for its capacity to upregulate the expression and activity of SIRT1, a critical mediator of neuroprotection via downstream signaling pathways. SIRT1, a key member of the Sirtuin family, is a nicotinamide adenine dinucleotide (NAD +)-dependent class III histone deacetylase. It plays an essential role in regulating cellular metabolism, energy homeostasis, gene expression, and cellular longevity. In the context of neurodegenerative diseases, SIRT1 confers neuroprotection by modulating multiple signaling cascades through deacetylation, suppressing neuronal apoptosis, and promoting neural repair and regeneration. Exercise enhances SIRT1 expression and activity by increasing NAD + synthesis and utilization, improving intracellular redox balance, alleviating oxidative stress-induced inhibition of SIRT1, and thereby promoting its activation. Moreover, exercise may indirectly modulate SIRT1 function by influencing interacting molecular networks. This review summarizes recent advances in the therapeutic application of exercise for neurodegenerative diseases, with a focus on SIRT1 as a central mechanism. It examines how exercise mediates neuroprotection through the regulation of SIRT1 and its associated molecular mechanisms and signaling pathways. Finally, the paper discusses the potential applications and challenges of integrating exercise and SIRT1-targeted strategies in the management of neurodegenerative diseases, offering novel perspectives for the development of innovative treatments and improvements in patients' quality of life.

The role of Klotho and sirtuins in sleep-related cardiovascular diseases: a review study

The prevalence of sleep disorders has been reported from 1.6% to 56.0%, worldwide. Sleep deprivation causes cardiovascular diseases (CVDs) including atherosclerosis, vascular aging, hypertension, heart dysfunction, reduced heart rate variability, and cardiac arrhythmia. Reduced tissue oxygen causes various CVDs by activating pro-inflammatory factors and increasing oxidative stress. Sleep disorders are more important and prevalent in older people and cause more severe cardiovascular complications. On the other hand, the reduction of Klotho level, an age-dependent protein whose expression decreases with age, is associated with age-related diseases. Sirtuins, class III histone deacetylases, also are among the essential factors in postponing cellular aging and increasing the lifespan of organisms, and they do this by regulating different pathways in the cell. Sirtuins and Klotho play an important role in the pathophysiology of CVDS and both have anti-oxidative stress and anti-inflammatory activity. Studies have shown that the levels of Klotho and sirtuins are altered in sleep disorders. In this article, alterations of Klotho and sirtuins in sleep disorders and in the development of sleep-related CVDs were reviewed and the possible signaling pathways were discussed. The inclusion criteria were studies with keywords of different types of sleep disorders and CVDs, klotho, SIRT1-7, and sirtuins in PubMed, Scopus, Embase، Science Direct، Web of Sciences and Google Scholar by the end of 2023. The studies revealed there is a bidirectional relationship between sleep disorders and the serum and tissue levels of Klotho and sirtuins and sleep related-CVDs.

The mechanism and therapeutic strategies in doxorubicin-induced cardiotoxicity: Role of programmed cell death

Doxorubicin (DOX) is the most commonly used anthracycline anticancer agent, while its clinical utility is limited by harmful side effects like cardiotoxicity. Numerous studies have elucidated that programmed cell death plays a significant role in DOX-induced cardiotoxicity (DIC). This review summarizes several kinds of programmed cell death, including apoptosis, pyroptosis, necroptosis, autophagy, and ferroptosis. Furthermore, oxidative stress, inflammation, and mitochondrial dysfunction are also important factors in the molecular mechanisms of DIC. Besides, a comprehensive understanding of specific signal pathways of DIC can be helpful to its treatment. Therefore, the related signal pathways are elucidated in this review, including sirtuin deacetylase (silent information regulator 2 [Sir2]) 1 (SIRT1)/nuclear factor erythroid 2-related factor 2, SIRT1/Klotho, SIRT1/Recombinant Sestrin 2, adenosine monophosphate-activated protein kinase, AKT, and peroxisome proliferator-activated receptor. Heat shock proteins function as chaperones, which play an important role in various stressful situations, especially in the heart. Thus, some of heat shock proteins involved in DIC are also included. Hence, the last part of this review focuses on the therapeutic research based on the mechanisms above.

ACTIVATION OF KLOTHO/SIRT1 SIGNALING PATHWAY ATTENUATES MYOCARDIAL ISCHEMIA REPERFUSION INJURY IN DIABETIC RATS

ABSTRACT

Diabetes and myocardial ischemia reperfusion (MIR) injury are characterized by oxidative stress, inflammation, autophagy disorders, and cardiac contractile dysfunction. Klotho and SIRT1 regulate the level of oxidative stress to participate in the regulation of many physiological functions such as cell survival, aging, apoptosis, autophagy, mitochondrial biogenesis, and inflammation. We hypothesized that the activation of Klotho/SIRT1 signaling pathway could attenuate MIR in diabetic rats. Type 1 diabetes and MIR injury model were established to examine this hypothesis in vivo . Primary rat cardiomyocytes and H9c2 cells were exposed to high glucose conditions and hypoxia/reoxygenation (H/R) insult in vitro . Hemodynamic parameters of heart function, myocardial infarct size, oxidative stress, markers of MIR injury or cell viability, and the mRNA and protein expression of Klotho and SIRT1 were measured. There was lower expression of Klotho and SIRT1 in diabetic MIR hearts than in nondiabetic rats, as well as significantly increased oxidative stress levels and decreased autophagy levels. Recombinant Klotho (rKlotho) protein and the SIRT1 agonist SRT1720 could significantly attenuate MIR injury in diabetes by activating Klotho/SIRT1 signaling pathway to reduce oxidative stress and restore autophagy levels. These findings suggest that the Klotho/SIRT1 pathway plays an important role in MIR injury in diabetic rats, and rKlotho protein and agonist SRT1720 have therapeutic potential for alleviating diabetic myocardial IR injury by activating Klotho/SIRT1 to reduce oxidative stress and restore autophagy levels.

Aerobic exercise and metformin on intermuscular adipose tissue (IMAT): insights from multimodal MRI and histological changes in prediabetic rats

BACKGROUND

Physical exercise is the first-line intervention for prediabetes, and metformin is the most widely used oral insulin-sensitizing agent. Moreover, intermuscular adipose tissue (IMAT) directly affects insulin resistance by helping maintain glucose homeostasis. Here, we evaluated the effects of moderate aerobic exercise and/or metformin on histological IMAT parameters in non-streptozotocin-induced prediabetes.

METHODS

Male Wistar rats with prediabetes fed a high-fat diet and high-sugar drinks were randomly assigned to high-fat diet (PRE), metformin (MET), moderate aerobic exercise (EXE), combined therapy (EMC), or EMC + compound-c (EMA) groups for 4 weeks. Multimodal magnetic resonance imaging (MRI) was then performed, and tissue-specific inflammation and energy and lipid metabolism were evaluated in IMAT.

RESULTS

The EXE group had lower inflammatory factor levels, lipid metabolism, and mitochondrial oxidative stress, and shorter IMAT adipocyte diameters than the MET group. The MET group exhibited lower IL-1β and Plin5 expression than the PRE group. Furthermore, the IMAT of the EMC group had lower TNF-α and phosphorylated NF-κB levels and higher GLUT1 and GLUT4 expression than the PRE group. Multimodal MRI revealed significant changes in transverse-relaxation time 2, apparent diffusion coefficient, and fractional anisotropy values in the IMAT and muscles, as well as lower IMAT% values in the EXE and EMC groups than in the MET and PRE groups.

CONCLUSION

Moderate aerobic exercise training can effectively improve IMAT function and structure via the AMP-activated protein kinase pathway in prediabetes. Combining metformin with moderate aerobic exercise might elicit modest synergy, and metformin does not counterbalance the beneficial effects of exercise.

Interaction of Klotho and sirtuins

OBJECTIVE

In this article, we review the articles that have reported the interaction between Klotho and sirtuins.

RECENT FINDINGS

Sirtuins are a family of histone deacetylase enzymes that are considered to be the main regulators of biological processes. This family is one of the essential factors for postponing aging and increasing the life span of organisms. Sirtuins play a role in regulating the function of various cellular processes such as cellular metabolism, oxidative stress, apoptosis, and inflammation. It has also been shown that various diseases are related to these enzymes. Klotho is an anti-aging protein that exists as a membrane protein as well as a soluble circulating form. The membrane type of this protein acts as a co-receptor of the FGF endocrine family. It has been shown that the Klotho gene is related to age-related diseases, including osteoporosis, coronary artery, brain diseases, diabetes, etc. At the same time, it is difficult to separate the actions of Klotho and endocrine FGFs. Several studies have shown that Klotho and sirtuins interact with each other at different regulatory levels. However, it is necessary to carry out more in-vivo investigations to create new windows towards the treatment or prevention of various diseases.

Treatment for Myocardial Infarction: In Vivo Evaluation of Curcumin-Loaded PEGylated-GQD Nanoparticles

ABSTRACT

Curcumin (Cur) has been suggested as a complementary treatment for cardiovascular diseases. Its efficiency, however, is modest due to poor biocompatibility. This study examined the effects of curcumin loaded on polyethylene glycol-graphene quantum dots (Cur-PEG-GQDs) on hemodynamic and cardiac function in rats with myocardial infarction (MI). The study groups included control, MI, MI+Cur-3, MI + Cur-7, MI + Cur-15, MI + PEG-GQDs-5, MI + PEG-GQDs-10, MI + Cur-PEG-GQDs-5, and MI + Cur-PEG-GQDs-10. MI was established by left anterior descending artery ligation. Two weeks after intraperitoneal administration of vehicle, Cur, PEG-GQDs, and Cur-PEG-GQDs, blood pressure and heart contractility indices were measured. Triphenyl tetrazolium chloride, colorimetry, and clinical laboratory methods were used to measure the infarct size, the oxidant and antioxidant content, and the kidney and liver function parameters, respectively. In the MI animals, Cur-7, PEG-GQDs-10, Cur-PEG-GQDs-5, and Cur-PEG-GQDs-10 recovered systolic blood pressure, diastolic blood pressure, left ventricular systolic pressure, and ±dp/dt max disturbances and reduced myocardial infarct size, fibrosis, and left ventricular end-diastolic pressure. Curcumin lowered antioxidant markers and elevated 1 oxidant marker in the heart in a dose-dependent manner. Although Cur-PEG-GQDs-5 and Cur-PEG-GQDs-10 reduced curcumin's oxidative stress effects, the superoxide dismutase, glutathione peroxidase, and total antioxidant capacity levels were significantly lower in Cur-PEG-GQDs-5 and Cur-PEG-GQDs-10 groups compared with the MI group. Malondialdehyde levels were lower in Cur-PEG-GQDs-5 and -10 groups compared with the Cur-3, Cur-7, and Cur-15 groups. The glutathione/glutathione disulfide ratio improved in the groups treated by Cur-7, PEG-GQDs-10, Cur-PEG-GQDs-5, and Cur-PEG-GQDs-10. The findings indicated that Cur-PEG-GQDs mitigated MI-induced cardiac dysfunction. However, because of the increase in oxidative stress in the heart, nonclassic mechanisms may be involved in the beneficial effect of Cur-PEG-GQDs on MI-induced cardiac dysfunction.

Cognitive decline in heart failure: Biomolecular mechanisms and benefits of exercise

By definition, heart failure (HF) is a human pathological condition affecting the structure and function of all organs in the body, and the brain is not an exception to that. Failure of the heart to pump enough blood centrally and peripherally is at the foundation of HF patients' inability to attend even the most ordinary daily activities and progressive deterioration of their cognitive capacity. What is more, between heart and brain exists a bidirectional relationship that goes well beyond hemodynamics and concerns bioelectric and endocrine signaling. This increasingly consolidated evidence makes the scenario even more complex. Studies have mainly chased how HF impairs cognition without focusing much on preventive measures, notably cardio-cerebral health proxies. Here, we aim to provide a brief account of known and hypothetical factors that may explain how exercise can help obviate cognitive dysfunction associated with HF in its different forms. As we shall see, there is a stringent need for a deeper grasp of such mechanisms. Indeed, gaining this new knowledge will automatically shed new light on the inner workings of HF itself, thus resulting in more effective prevention and treatment of this escalating syndrome.

Exercise Training Attenuates Cardiac Vulnerability and Promotes Cardiac Resistance to Isoproterenol-Induced Injury Following Hookah Smoke Inhalation in Male Rats: Role of Klotho and Sirtuins

Hookah smoking is on the rise around the world. Present study investigated the heart resistance to harmful stress following long-term waterpipe tobacco smoking (WTS) and moderate-intensity exercise training intervention in male Wistar rats. Animals were randomly divided into a non-ischemic heart control group and four ischemic heart groups including ISO (isoproterenol-treated), Ex + ISO (subjected to exercise plus ISO), S + ISO (exposed to hookah smoke plus ISO), and Ex + S + ISO (subjected to exercise along with hookah smoke plus ISO). After eight weeks of training and WTS, heart ischemia induced by isoproterenol injections. Then, cardiac functional indices and some biochemical and histopathological parameters were assessed. WTS + ISO reduced systolic pressure, ± dP/dt max, and contractility indices (P < 0.001 vs. ISO group) and increased end diastolic pressure and Tau index (P < 0.001 vs. ISO) of the left ventricle. Also, WTS + ISO was associated with an increase in Bax protein level and Bax/Bcl-2 ratio (P < 0.05 and P < 001, respectively, vs. ISO group) as apoptotic markers of heart tissue. Hookah smoke significantly decreased SIRT1 (P < 0.05 and P < 0.001, respectively, vs. ISO) and klotho (P < 0.01 and P < 0.001, respectively, vs. ISO) in serum and heart, and SIRT3 and pS9-GSK-3β (P < 001 and P < 0.05, respectively, vs. ISO) in heart tissue. Combination of exercise with WTS prevented the hookah smoke-induced alterations in apoptotic markers, cardiac functional indices, and SIRT1, SIRT3, klotho, and pS9-GSK-3β proteins. The findings demonstrated that hookah smoke inhalation intensifies ventricular dysfunction and decreases heart resistance to harmful stresses. Moderate-intensity exercise training attenuated these complications partly through recovering the klotho and sirtuins levels and apoptosis-survival balancing.

PEGylated Graphene Quantum Dot Improved Cardiac Function in Rats with Myocardial Infarction: Morphological, Oxidative Stress, and Toxicological Evidences

Introduction

The biocompatibility and potential application of graphene-based nanomaterials in biomedicine have been documented. The effects of polyethylene glycol-graphene quantum dots (GQDs-PEG) on cardiac function in rats with myocardial infarction (MI) were examined.

Methods

Wistar rats were randomly assigned to two main groups, each consisting of sham-Veh., MI-Veh., and MI+GQDs-PEG at doses of 5, 10, and 20 mg/kg. MI was induced by the closure of the left anterior descending (LAD) coronary artery. After MI, GQDs-PEG were injected at different doses IP every other day for two weeks. In the end, hemodynamic and heart contractility indices were assessed. The levels of myocardial MDA (malondialdehyde), SOD (superoxide dismutase), GPX (glutathione peroxidase), and TAC (total antioxidant capacity) were measured by the ELISA method. The serum ALP, ALT, AST, creatinine, and urea levels were measured using the photometric method. The infarct size was assessed by TTC staining.

Results

GQDs-PEG decreased the infarct size at doses of 10 and 20 mg/kg and recovered the MI-induced reductions of +dp/dt max and -dp/dt max in the study groups. GQDs-PEG normalized systolic blood pressure and left ventricular systolic pressure reduction at the dose of 20 mg/kg in the MI group. Heart SOD, GPX, and TAC increased in the GQDs-PEG 10 and 20 groups. Almost no signs of toxic effects due to GQDs-PEG administration were observed on the liver and kidneys.

Conclusions

The results provided clear evidence that GQDs-PEG improve cardiac performance and hemodynamic parameters in rats with MI by reducing oxidative stress. GQDs-PEG is proposed as a therapeutic target for the treatment of MI.

Beneficial effects of PEGylated graphene quantum dot on arrhythmias induced by myocardial infarction

Arrhythmias are one of the leading causes of early death following myocardial infarction (MI) and heart failure. Graphene derivatives have emerged as an therapeutic target that have electrical conductivity. The study aimed to evaluate the impacts of polyethylene glycol-graphene quantum dots (GQDs-PEG) on arrhythmias created by MI in the rat. Animals were randomly assigned to five groups of sham, MI, and MI + GQDs-PEG at doses of 5, 10, and 20 mg/kg. MI was induced by the closure of the left anterior descending artery. The day after MI, animals were administered vehicle (phosphate buffered saline) or GQDs-PEG at different doses every other day for 2 weeks. On day 15, electrocardiogram (ECG), mean arterial pressure (MAP), and heart contractility indices were recorded by the PowerLab data acquisition system. GQDs-PEG 20 mg/kg increased contractility and improved the reduction of MAP in the MI group. The prolonged QT and QTc intervals, inverted T wave, and deviated ST segment were modified by GQDs-PEG 10 and 20 mg/kg in rats with MI. The amplitude of the Q wave was also decreased in a dose-dependent manner in the GQDs-PEG-treated rats. The results demonstrated that 2 weeks of treatment with GQDs-PEG normalized ECG abnormalities and improved left ventricular dysfunction in rats with MI.

Sirtuin 1 in Endothelial Dysfunction and Cardiovascular Aging

Sirtuin 1 (SIRT1) is a histone deacetylase belonging to the family of Sirtuins, a class of nicotinamide adenine dinucleotide (NAD+)-dependent enzymes with multiple metabolic functions. SIRT1 localizes in the nucleus and cytoplasm, and is implicated in the regulation of cell survival in response to several stimuli, including metabolic ones. The expression of SIRT1 is associated with lifespan and is reduced with aging both in animal models and in humans, where the lack of SIRT1 is regarded as a potential mediator of age-related cardiovascular diseases. In this review, we will summarize the extensive evidence linking SIRT1 functional and quantitative defects to cellular senescence and aging, with particular regard to their role in determining endothelial dysfunction and consequent cardiovascular diseases. Ultimately, we outline the translational perspectives for this topic, in order to highlight the missing evidence and the future research steps.

Involvement of Sirtuins and Klotho in Cardioprotective Effects of Exercise Training Against Waterpipe Tobacco Smoking-Induced Heart Dysfunction

Despite its negative effect on the cardiovascular system, waterpipe smoking (WPS) is currently popular worldwide, especially among youth. This study investigated the effects of moderate endurance exercise on heart function of rats exposed to WPS and its possible mechanism. The animals were randomly divided into four groups: control group (CTL), the exercise group (Ex) which trained for 8 weeks, the waterpipe tobacco smoking group (S) exposed to smoke inhalation (30 min per day, 5 days each week, for 8 weeks), and the group that did exercise training and received waterpipe tobacco smoke inhalation together (Ex + S). One day after the last session of Ex and WPS, cardiac pressures and functional indices were recorded and calculated. The levels of SIRT1, SIRT3, Klotho, Bax, and Bcl-2 in the serum and heart, the expression of phosphorylated GSK3β of heart tissue, and cardiac histopathological changes were assessed. WPS reduced systolic pressure, +dP/dt max, -dP/dt max, and heart contractility indices (P < 0.001 vs. CTL) and increased cardiac tissue lesions (P < 0.05 vs. CTL) and end diastolic pressure and Tau index (P < 0.001 vs. CTL) of the left ventricle. Exercise training normalized the left ventricular end diastolic pressure, +dP/dt max, and contractility index. Also, exercise improved the levels of SIRT1, SIRT3, Klotho, and Bcl-2 and reduced Bax level in the heart. The findings showed that WPS causes left ventricular dysfunction. Moderate exercise prevented WPS-induced heart dysfunction partly through its anti-apoptotic features and activation of the sirtuins and Klotho pathways.

Sirtuins-Mediated System-Level Regulation of Mammalian Tissues at the Interface between Metabolism and Cell Cycle: A Systematic Review

Sirtuins are a family of highly conserved NAD+-dependent proteins and this dependency links Sirtuins directly to metabolism. Sirtuins' activity has been shown to extend the lifespan of several organisms and mainly through the post-translational modification of their many target proteins, with deacetylation being the most common modification. The seven mammalian Sirtuins, SIRT1 through SIRT7, have been implicated in regulating physiological responses to metabolism and stress by acting as nutrient sensors, linking environmental and nutrient signals to mammalian metabolic homeostasis. Furthermore, mammalian Sirtuins have been implicated in playing major roles in mammalian pathophysiological conditions such as inflammation, obesity and cancer. Mammalian Sirtuins are expressed heterogeneously among different organs and tissues, and the same holds true for their substrates. Thus, the function of mammalian Sirtuins together with their substrates is expected to vary among tissues. Any therapy depending on Sirtuins could therefore have different local as well as systemic effects. Here, an introduction to processes relevant for the actions of Sirtuins, such as metabolism and cell cycle, will be followed by reasoning on the system-level function of Sirtuins and their substrates in different mammalian tissues. Their involvement in the healthy metabolism and metabolic disorders will be reviewed and critically discussed.