D-galactose induces a mitochondrial complex I deficiency in mouse skeletal muscle: potential benefits of nutrient combination in ameliorating muscle impairment

Role of mitochondrial homeostasis in D-galactose-induced cardiovascular ageing from bench to bedside

Ageing is an inevitable phenomenon which affects the cellular to the organism level in the progression of the time. Oxidative stress and inflammation are now widely regarded as the key processes involved in the aging process, which may then cause significant harm to mitochondrial DNA, leading to apoptosis. Normal circulatory function is a significant predictor of disease-free life expectancy. Indeed, disorders affecting the cardiovascular system, which are becoming more common, are the primary cause of worldwide morbidity, disability, and mortality. Cardiovascular aging may precede or possibly underpin overall, age-related health decline. Numerous studies have foundmitochondrial mechanistc approachplays a vital role in the in the onset and development of aging. The D-galactose (D-gal)-induced aging model is well recognized and commonly used in the aging study. In this review we redeposit the association of the previous and current studies on mitochondrial homeostasis and its underlying mechanisms in D-galactose cardiovascular ageing. Further we focus the novel and the treatment strategies to combat the major complication leading to the cardiovascular ageing.

Matrix mechanics regulates muscle regeneration by modulating kinesin-1 activity

Sarcopenia, a prevalent muscle disease characterized by muscle mass and strength reduction, is associated with impaired skeletal muscle regeneration. However, the influence of the biomechanical properties of sarcopenic skeletal muscle on the efficiency of the myogenic program remains unclear. Herein, we established a mouse model of sarcopenia and observed a reduction in stiffness within the sarcopenic skeletal muscle in vivo. To investigate whether the biomechanical properties of skeletal muscle directly impact the myogenic program, we established an in vitro system to explore the intrinsic mechanism involving matrix stiffness control of myogenic differentiation. Our findings identify the microtubule motor protein, kinesin-1, as a mechano-transduction hub that senses and responds to matrix stiffness, crucial for myogenic differentiation and muscle regeneration. Specifically, kinesin-1 activity is positively regulated by stiff matrices, facilitating its role in transporting mitochondria and enhancing translocation of the glucose transporter GLUT4 to the cell surface for glucose uptake. Conversely, the softer matrices significantly suppress kinesin-1 activity, leading to the accumulation of mitochondria around nuclei and hindering glucose uptake by inhibiting GLUT4 membrane translocation, consequently impairing myogenic differentiation. The insights gained from the in-vitro system highlight the mechano-transduction significance of kinesin-1 motor proteins in myogenic differentiation. Furthermore, our study confirms that enhancing kinesin-1 activity in the sarcopenic mouse model restores satellite cell expansion, myogenic differentiation, and muscle regeneration. Taken together, our findings provide a potential target for improving muscle regeneration in sarcopenia.

D-galactose might mediate some of the skeletal muscle hypertrophy-promoting effects of milk-A nutrient to consider for sarcopenia?

Sarcopenia is a process of progressive aging-associated loss of skeletal muscle mass (SMM) recognized as a serious global health issue contributing to frailty and increased all-cause mortality. Exercise and nutritional interventions (particularly intake of dairy products and milk) demonstrate good efficacy, safety, and broad applicability. Here, we propose that at least some of the well-documented favorable effects of milk and milk-derived protein supplements on SMM might be mediated by D-galactose, a monosaccharide present in large quantities in milk in the form of disaccharide lactose (milk sugar). We suggest that ingestion of dairy products results in exposure to D-galactose in concentrations metabolized primarily via the Leloir pathway with the potential to (i) promote anabolic signaling via maintenance of growth factor (e.g., insulin-like growth factor 1 [IGF-1]) receptor mature glycosylation patterns; and (ii) provide extracellular (liver glycogen) and intracellular substrates for short (muscle glycolysis) and long-term (muscle glycogen, intramyocellular lipids) energy availability. Additionally, D-galactose might optimize the metabolic function of skeletal muscles by increasing mitochondrial content and stimulating glucose and fatty acid utilization. The proposed potential of D-galactose to promote the accretion of SMM is discussed in the context of its therapeutic potential in sarcopenia.

Current understanding and future perspectives on the extraction, structures, and regulation of muscle function of tea pigments

With the aggravating aging of modern society, the sarcopenia-based aging syndrome poses a serious potential threat to the health of the elderly. Natural dietary supplements show great potential to reduce muscle wasting and enhance muscle performance. Tea has been widely recognized for its health-promoting effects. which contains active ingredients such as tea polyphenols, tea pigments, tea polysaccharides, theanine, caffeine, and vitamins. In different tea production processes, the oxidative condensation and microbial transformation of catechins and other natural substances from tea promotes the production of various tea pigments, including theaflavins (TFs), thearubigins (TRs), and theabrownins (TBs). Tea pigments have shown a positive effect on maintaining muscle health. Nevertheless, the relationship between tea pigments and skeletal muscle function has not been comprehensively elucidated. In addition, the numerous research on the extraction and purification of tea pigments is disordered with the limited recent progress due to the complexity of species and molecular structure. In this review, we sort out the strategies for the separation of tea pigments, and discuss the structures of tea pigments. On this basis, the regulation mechanisms of tea pigments on muscle functional were emphasized. This review highlights the current understanding on the extraction methods, molecular structures and regulation mechanisms of muscle function of tea pigments. Furthermore, main limitations and future perspectives are proposed to provide new insights into broadening theoretical research and industrial applications of tea pigments in the future.

Chronic D-Galactose Administration Induces Natural Aging Characteristics, in Rat's Brain and Heart

We aimed to investigate the effect of chronic D-galactose exposure on the mimicking of natural aging processes based upon the hallmarks of aging. Seven-week-old male Wistar rats (n = 12) were randomly assigned to receive either normal saline solution as a vehicle (n = 6) or 150mg/kg/day of D-galactose subcutaneously for 28 weeks. Seventeen-month-old rats (n = 6) were also included as the chronologically aged controls. At the end of week 28 of the experiment (when the rats reach 35 weeks old and 24 months old), all rats were sacrificed for brain and heart collection. Our results showed that chronic D-galactose exposure mimicked natural aging characteristics of the brain and the heart in terms of deregulated nutrient sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, altered intercellular communication, and functional impairment. All of which highlight the potential of D-galactose as a substance for inducing brain and cardiac aging in animal experiments. DATA AVAILABILITY: The data that support the findings of this study are available from the corresponding author upon reasonable request.

Effects of acupuncture on the miR-146a-mediated IRAK1/TRAF6/NF-κB signaling pathway in rats with sarcopenia induced by D-galactose

Background

Sarcopenia during aging is closely linked to sterile, low-grade, chronic inflammation. However, considering the increasingly aging global population, the effectiveness of existing treatments for sarcopenia is not exact, and acupuncture, as an effective anti-inflammatory therapy, has the potential to treat it.

Methods

Fifty Sprague-Dawley rats were randomly allocated into five groups, including Control group, D-galactose (D-gal) group, D-gal + acupuncture (DA) group, D-gal + non-acupoint (DN) group and D-gal amino acid mixture (DAA) group. An aging rat was model constructed using D-gal for 12 weeks. Rats in the control group received 0.9% physiological saline daily. Treatment groups were acupunctured or given amino acid mixture interventions daily, and lasted for last 4 consecutive weeks. The effects of acupuncture were evaluated by the hematoxylin and eosin staining (H&E), transmission electron microscopic (TEM) examination and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assays. The anti-inflammatory mechanism of acupuncture was studied by using the expressions of microRNA-146a (miR-146a) mediated nuclear factor-kappa B (NF-κB) signaling pathway-related proteins were detected by immunofluorescence, western blotting, quantitative real-time polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA).

Results

Rats injected by D-galactose (D-gal) revealed apparent skeletal muscle atrophy with significantly reduced cross-sectional area and fiber diameter. In contrast, acupuncture treatment alleviated these hallmarks of skeletal muscle atrophy and mitigated the mitochondrial aberrations and skeletal muscle apoptosis in D-gal rats. In addition, acupuncture also downgraded the overexpression of inflammatory factors in skeletal muscle, influenced miR-146a and the target genes level, and inhibited NF-κB nuclear translation in D-gal rats.

Conclusions

Acupuncture may ameliorate skeletal muscle atrophy, and its effects may be associated with the control of mitochondrial function regulation and the suppression of inflammation.

ER stress in cardiac aging, a current view on the D-galactose model

Longitudinal studies are mandatory to study aging, however, they have certain drawbacks, for example, they require strict maintenance that is expensive given the breeding time (approximately 2 years) and with a low survival rate, having some animals to study very limitedly. In vitro studies provide useful and invaluable information on the cellular and molecular mechanisms that help understand the aging process to overcome these aspects. In particular, the model of premature aging induced by chronic exposure to D-galactose (D-Gal) offers a very similar picture to that which occurs in natural aging. This model mimics most of the old animals' cellular processes, such as oxidative stress, mitochondrial dysfunction, increased advanced glycation end products (AGEs), inflammation, and senescence-associated secretory phenotype (SASP). However, the information related to the endoplasmic reticulum (ER) stress and, subsequently, the unfolded protein response (UPR) is not fully elucidated. Therefore, this review brings together the most current information on this response in the D-Gal-induced aging model and its effect on cardiac structure and function.

Role and Mechanism of Theaflavins in Regulating Skeletal Muscle Inflammation

Persistent inflammatory infiltration of skeletal muscle is a principal trigger for the loss of muscle mass and strength. Theaflavins, the main functional components of black tea, have effects on muscle health, but their biological effects on skeletal muscle inflammation are unclear. We constructed in vitro and in vivo models of muscle inflammation and found that theaflavins reduced the expression of inflammatory factors (IL-1β, IL-6, and TNF-α) by regulating the TLR4/MyD88/NF-κB signaling pathway to alleviate muscle inflammation. In addition, TF1 can regulate the metabolic function of skeletal muscle under inflammatory conditions, reduce the content of proinflammatory substances, improve the mechanical properties (stiffness and roughness) of the surface of inflammatory myotubes, and promote the recovery of muscle after an inflammatory injury. In conclusion, theaflavins may serve as a diet-derived anti-inflammatory factor with potential modulatory effects on skeletal muscle metabolism and mechanical properties in an inflammatory environment.

Theaflavin Promotes Mitochondrial Abundance and Glucose Absorption in Myotubes by Activating the CaMKK2-AMPK Signal Axis via Calcium-Ion Influx

Drinking tea has been proven to have a positive biological effect in regulating human glucose and lipid metabolism and preventing type 2 diabetes (T2D). Skeletal muscle (SkM) is responsible for 70% of the sugar metabolism in the human body, and its dysfunction is an important factor leading to the development of obesity, T2D, and muscle diseases. As one of the four known theaflavins (TFs) in black tea, the biological role of theaflavin (TF1) in regulating SkM metabolism has not been reported. In this study, mature myotubes induced by C2C12 cells in vitro were used as models. The results showed that TF1 (20 μM) promoted mitochondrial abundance and glucose absorption in myotubes by activating the CaMKK2-AMPK signaling axis via Ca²⁺ influx. Moreover, it promoted the expression of slow muscle fiber marker genes (Myh7, Myl2, Tnnt1, and Tnnc1) and PGC-1α/SIRT1, as well as enhanced the oxidative phosphorylation capacity of myotubes. In conclusion, this study preliminarily clarified the potential role of TF1 in regulating SkM glucose absorption as well as promoting SkM mitochondrial biosynthesis and slow muscle fiber formation. It has potential research and application values for the prevention/alleviation of SkM-related T2D and Ca²⁺-related skeletal muscle diseases through diet.

Alginate oligosaccharide alleviates D-galactose-induced cardiac ageing via regulating myocardial mitochondria function and integrity in mice

Ageing is a crucial risk factor for the development of age‐related cardiovascular diseases. Therefore, the molecular mechanisms of ageing and novel anti‐ageing interventions need to be deeply studied. Alginate oligosaccharide (AOS) possesses high pharmacological activities and beneficial effects. Our study was undertaken to investigate whether AOS could be used as an anti‐ageing drug to alleviate cardiac ageing. D‐galactose (D‐gal)‐induced C57BL/6J ageing mice were established by subcutaneous injection of D‐gal (200 mg·kg^‐1·d^‐1) for 8 weeks. AOS (50, 100 and 150 mg·kg^‐1·d^‐1) were administrated intragastrically for the last 4 weeks. As a result, AOS prevented cardiac dysfunction in D‐gal‐induced ageing mice, including partially preserved ejection fraction (EF%) and fractional shortening (FS%). AOS inhibited D‐gal‐induced up‐regulation of natriuretic peptides A (ANP), brain natriuretic peptide (BNP) and ageing markers p53 and p21 in a dose‐dependent manner. To further explore the potential mechanisms contributing to the anti‐ageing protective effect of AOS, the age‐related mitochondrial compromise was analysed. Our data indicated that AOS alleviated D‐gal‐induced cardiac ageing by improving mitochondrial biogenesis, maintaining the mitochondrial integrity and enhancing the efficient removal of impaired mitochondria. AOS also decreased the ROS production and oxidative stress status, which, in turn, further inhibiting cardiac mitochondria from being destroyed. Together, these results demonstrate that AOS may be an effective therapeutic agent to alleviate cardiac ageing.

Fisetin Rescues the Mice Brains Against D-Galactose-Induced Oxidative Stress, Neuroinflammation and Memory Impairment

Herein, we have evaluated the protective potentials of Fisetin against d-galactose-induced oxidative stress, neuroinflammation, and memory impairment in mice. d-galactose (D-gal) causes neurological impairment by inducing reactive oxygen species (ROS), neuroinflammation, and synaptic dysfunction, whereas fisetin (Fis) is a natural flavonoid having potential antioxidant effects, and has been used against different models of neurodegenerative diseases. Here, the normal mice were injected with D-gal (100 mg/kg/day for 60 days) and fisetin (20 mg/kg/day for 30 days). To elucidate the protective effects of fisetin against d-galactose induced oxidative stress-mediated neuroinflammation, we conducted western blotting, biochemical, behavioral, and immunofluorescence analyses. According to our findings, D-gal induced oxidative stress, neuroinflammation, synaptic dysfunctions, and cognitive impairment. Conversely, Fisetin prevented the D-gal-mediated ROS accumulation, by regulating the endogenous anti-oxidant mechanisms, such as Sirt1/Nrf2 signaling, suppressed the activated p-JNK/NF-kB pathway, and its downstream targets, such as inflammatory cytokines. Hence, our results together with the previous reports suggest that Fisetin may be beneficial in age-related neurological disorders.

Theaflavin Promotes Myogenic Differentiation by Regulating the Cell Cycle and Surface Mechanical Properties of C2C12 Cells

Aging and muscle diseases often lead to a decline in the differentiation capacity of myoblasts, which in turn results in the deterioration of skeletal muscle (SkM) function and impairment of regeneration ability after injury. Theaflavins, the "gold molecules" found in black tea, have been reported to possess various biological activities and have a positive effect on maintaining human health. In this study, we found that among the four theaflavins (theaflavin (TF1), theaflavin-3-gallate (TF2A), theaflavin-3'-gallate (TF2B), and theaflavin-3,3'-digallate (TF3) monomers), TF1 (20 μM) significantly promoted the fusion index of myoblasts, number of mature myotubes, and degree of myotube development. By combining transcriptomics, bioinformatics, and molecular biology experiments, we showed that TF1 may promote myoblast differentiation by (1) regulating the withdrawal of myoblasts from the cell cycle, inducing the release of myogenic factors (MyoD, MyoG, and MyHC) and accelerating myogenic differentiation and (2) regulating the adhesion force of myoblasts and mechanical properties of mature myotubes and promoting the migration, fusion, and development of myoblasts. In conclusion, our study outcomes show that TF1 can promote myoblast differentiation and regulate myotube mechanical properties. It is a potential dietary supplement for the elderly. Our findings provide a new scientific basis for the relationship between tea drinking and aging.

Galactose-Induced Skin Aging: The Role of Oxidative Stress

Skin aging has been associated with a higher dietary intake of carbohydrates, particularly glucose and galactose. In fact, the carbohydrates are capable of damaging the skin's vital components through nonenzymatic glycation, the covalent attachment of sugar to a protein, and subsequent production of advanced glycation end products (AGEs). This review is focused on the role of D-galactose in the development of skin aging and its relation to oxidative stress. The interest in this problem was dictated by recent findings that used in vitro and in vivo models. The review highlights the recent advances in the underlying molecular mechanisms of D-galactose-mediated cell senescence and cytotoxicity. We have also proposed the possible impact of galactosemia on skin aging and its clinical relevance. The understanding of molecular mechanisms of skin aging mediated by D-galactose can help dermatologists optimize methods for prevention and treatment of skin senescence and aging-related skin diseases.

The roles of resveratrol on cardiac mitochondrial function in cardiac diseases

Left ventricular (LV) dysfunction is commonly associated with a variety of health conditions including acute myocardial infarction and obesity/diabetes. In addition, administration of several pharmacological agents such as anticancer, antiviral, and immunosuppressive drugs has been shown to be related with LV dysfunction. The molecular mechanism responsible for LV dysfunction has been extensively studied, and it has been proposed that the overproduction of reactive oxygen species (ROS) plays a crucial role in the regulation of this function. Mitochondria require the balance between ROS production and antioxidants to maintain their appropriate function and to prevent excessive ROS production. Thus, the excessive production of ROS and the reduced scavenging process under any pathological conditions could disrupt mitochondrial function, leading to energy depletion with subsequent cell death. Therefore, maintenance of the balance between oxidative stress and antioxidants is essential. Resveratrol, a stilbene, has been investigated extensively, and potentially used to treat or prevent various cardiovascular diseases. Resveratrol directly upregulates antioxidative capacity by increasing antioxidant genes such as heme oxygenase-1, superoxide dismutase, catalase, and glutathione. In this review, accumulated data from in vitro, ex vivo, and in vivo studies regarding the effects of resveratrol on cardiac mitochondrial function in cardiac pathologies are comprehensively summarized and discussed. Since there is no conclusive available clinical study regarding the effects of resveratrol on cardiac mitochondrial function, this review also aims to encourage more clinical investigations to confirm findings from basic research. This comprehensive review will provide insight regarding the potential mechanistic roles of resveratrol in preventing and/or treating patients with cardiovascular diseases to improve LV function and their health status.

Ginsenoside Rg1 ameliorates the cognitive deficits in D-galactose and AlCl3-induced aging mice by restoring FGF2-Akt and BDNF-TrkB signaling axis to inhibit apoptosis

Ginsenoside Rg1 is the main active ingredient of Panax ginseng with the activity of neuroprotective, antioxidant and strengthening the immune system. Therefore, we hypothesized that Rg1 may afford anti-aging effects although the mechanism remains to be elucidated. In this study, chemically induced aging mice were established by consecutive administration of D-galactose and AlCl₃. We found that Rg1 effectively ameliorates spatial learning and memory deficits in aging mice demonstrated by their improved performance in step down avoidance tests and Morris water maze experiments. Rg1 restored aging-induced decline of FGF2 and BDNF, reactivated TrkB/Akt signaling pathways in the hippocampus and prefrontal cortex to inhibit apoptosis, for the expression of anti-apoptotic protein Bcl-2 and apoptosis promoting enzyme cleaved-Caspase3 were antagonistically restored. Therefore, these results established the anti-aging effects of Rg1, and FGF2, BDNF and associated signaling pathways might be promising targets. Our data may provide a new avenue to the pharmacological research and diet therapeutic role of ethnic products such as Rg1 in anti-aging and aging associated diseases.

Examining Cardiomyocyte Dysfunction Using Acute Chemical Induction of an Ageing Phenotype

Much effort is focussed on understanding the structural and functional changes in the heart that underlie age-dependent deterioration of cardiac performance. Longitudinal studies, using aged animals, have pinpointed changes occurring to the contractile myocytes within the heart. However, whilst longitudinal studies are important, other experimental approaches are being advanced that can recapitulate the phenotypic changes seen during ageing. This study investigated the induction of an ageing cardiomyocyte phenotypic change by incubation of cells with hydroxyurea for several days ex vivo. Hydroxyurea incubation has been demonstrated to phenocopy age- and senescence-induced changes in neurons, but its utility for ageing studies with cardiac cells has not been examined. Incubation of neonatal rat ventricular myocytes with hydroxyurea for up to 7 days replicated specific aspects of cardiac ageing including reduced systolic calcium responses, increased alternans and a lesser ability of the cells to follow electrical pacing. Additional functional and structural changes were observed within the myocytes that pointed to ageing-like remodelling, including lipofuscin granule accumulation, reduced mitochondrial membrane potential, increased production of reactive oxygen species, and altered ultrastructure, such as mitochondria with disrupted cristae and disorganised myofibres. These data highlight the utility of alternative approaches for exploring cellular ageing whilst avoiding the costs and co-morbid factors that can affect longitudinal studies.

Pro-neurocognitive and anti-sarcopenic benefits of one-year metformin therapy in ovariectomized aged mice

Health promotion and healthy nutrition significantly increased life expectancy around the world. Aging is associated with an increase in age-related diseases. The use of metformin (Met) as an anti-aging drug has recently been proposed based on its widespread use in clinical practice. Reports have shown that Met acts as an anti-aging agent. In this study, the effects of long-term, 1 year, Met administration on aging-related behaviors and longevity in ovariectomized mice was studied. Met (1 and 10 mg/kg, daily) was administered orally in ovariectomized mice. The anxiety-like behavior, working memory, and physical strength were measured through elevated plus maze, Y-maze, vertical grid holding, and the obligatory swimming capacity tests. Brains were harvested to measure brain-derived neurotrophic factor (BDNF) level. Also, the Kaplan-Meier survival curves were used to show differences and similarities in survival patterns. Met (10 mg/kg) decreased anxiety-like behaviors as well as increased muscle strength and working memory in the ovariectomized mice. Moreover, Met increased the physical strength and longevity as well as the level of BDNF in the ovariectomized mice. Our results indicate that Met administration can be an effective strategy for having a healthy aging in the absence of female gonadal hormones and reverses deleterious effects of ovariectomy-induced aging possibly through BDNF.

Sexual Dimorphism in the Behavioral Responses and the Immunoendocrine Status in d-Galactose-Induced Aging

For almost 20 years, chronic systemic d-galactose, a monosaccharide abundantly present in milk products, fruits, and vegetables, has been used as a tool to achieve models of accelerated aging. Its neurotoxicity, induced by abnormal accumulation of reactive oxygen species and advanced glycation end products, has been widely reported. However, behavioral outcomes are still controversial and little is known about sex-dependent vulnerability. We performed a comprehensive behavioral and multifunctional screening of the chronic effects of low (50 mg/kg) and high (100 mg/kg) doses of d-galactose in 6-month-old male and female gold-standard C57BL/6 mice. Twelve classical tests with convergent validity analyzed sensorimotor, emotional and cognitive domains, indicating the existence of thresholds of response. Distinct vulnerability patterns were found in a selective sex- and dose-dependent manner. In males, d-galactose induced sensorimotor impairment and immunoendocrine senescence, but the low dose resulted in improved learning and memory. Oppositely, d-galactose-treated females exhibited a dose-dependent worse motor and spatial learning, but improved memory. Behavioral outcome items point at distinct neuronal substrates underlying the functional capacity of d-galactose-treated animals to meet task-dependent performance demands. They support that males and females can be regarded as two exceptional natural scenarios to study the functional interplay in the cross talk of homeostatic networks in aging.

Is D-Galactose a Useful Agent for Accelerated Aging Model of Gastrocnemius and Soleus Muscle of Sprague-Dawley Rats?

Elderly population and age-related diseases are on the rise. On the contrary, aging studies are technically hard to conduct, because they require elderly animals, the maintenance of which requires ample effort and is expensive. To tackle this problem, D-galactose is used to hasten the aging process in various tissues in rodent models and it has been shown to successfully mimic the oxidative alterations that take place in the natural aging process in various tissues both by our group and others. In the present study, the validity of D-galactose aging model in skeletal muscles was tested both on predominantly slow-twitch (soleus) and rather fast-twitch (gastrocnemius) muscle in male Sprague-Dawley rats and the results are compared with young littermate controls and naturally aged rats. Redox-related modifications in soleus and gastrocnemius were assessed by measurement of protein carbonyl groups, advanced oxidation protein products, lipid hydroperoxides, total thiol, and Cu, Zn-superoxide dismutase activities. In the present study, we provide biochemical evidence demonstrating that D-galactose-induced mimetic aging does result in oxidative stress-related redox alterations that are comparable with the alterations that occur in natural aging in soleus. On the contrary, in the D-galactose-induced mimetic aging of gastrocnemius, even though the oxidative stress markers were significantly increased, the endpoint redox homeostasis markers were not statistically comparable with the redox status of naturally aged group.

Effects of d-galactose-induced ageing on the heart and its potential interventions

Ageing is a strong independent risk factor for disability, morbidity and mortality. Post-mitotic cells including those in the heart are a particular risk to age-related deterioration. As the occurrence of heart disease is increasing rapidly with an ageing population, knowledge regarding the mechanisms of age-related cardiac susceptibility and possible therapeutic interventions needs to be acquired to prevent advancing levels of heart disease. To understand more about the ageing heart, numerous aged animal models are being used to explore the underlying mechanisms. Due to time-consuming for investigations involving naturally aged animals, mimetic ageing models are being utilized to assess the related effects of ageing on disease occurrence. d-galactose is one of the substances used to instigate ageing in various models, and techniques involving this have been widely used since 1991. However, the mechanism through which d-galactose induces ageing in the heart remains unclear. The aim of this review was to comprehensively summarize the current findings from in vitro and in vivo studies on the effects of d-galactose-induced ageing on the heart, and possible therapeutic interventions against ageing heart models. From this review, we hope to provide invaluable information for future studies and based on the findings from experiments involving animals, we can inform possible therapeutic strategies for the prevention of age-related heart diseases in clinical settings.

miR-21 suppression prevents cardiac alterations induced by d-galactose and doxorubicin

d-galactose (d-gal)-induced cardiac alterations and Doxorubicin (Dox)-induced cardiomyocyte senescence are commonly used models to study cardiac aging. Accumulating evidence has suggested that microRNAs (miRNAs, miRs) are critically involved in the regulation of cellular and organismal aging and age-related diseases. However, little has been revealed about the roles of miRNAs in cardiac alterations induced by d-gal and Dox. In this study, we used miRNA arrays to investigate the dysregulated miRNAs in heart samples from 15month-old versus 2month-old male C57BL/6 mice and further validated them in d-gal-induced pseudo-aging mouse model and Dox-induced cardiomyocyte senescence in vitro model. We confirmed a significant increase of miR-21 in all these models by quantitative reverse transcription polymerase chain reactions. We further demonstrated that miR-21 was able to promote Dox-induced cardiomyocyte senescence whereas suppression of miR-21 could prevent that, as determined by percentage of β-gal-positive cells and gene markers of aging. Phosphatase and tensin homolog (PTEN) was identified as a target gene of miR-21, mediating its effect in increasing cardiomyocyte senescence. Finally, we found that miR-21 knockout mice were resistant to d-gal-induced alterations in aging-markers and cardiac function. Collectively, this study provides direct evidence that inhibition of miR-21 is protective against d-gal-induced cardiac alterations and Dox-induced cardiomyocyte senescence via targeting PTEN. Inhibition of miR-21 might be a novel strategy to combat cardiac aging.

Multi-Protection of DL0410 in Ameliorating Cognitive Defects in D-Galactose Induced Aging Mice

D-galactose has been reported to accelerate senescence in rodents, accompanied by a decline in learning and memory. We used a model of D-galactose-induced amnesia for the efficacy evaluation and pharmacologic studies of active compounds against Alzheimer's disease (AD). DL0410 is a potent inhibitor against acetylcholinesterase (AChE) and, in the present study, the effect of DL0410 was evaluated in this model. We found that DL0410 could significantly improve the learning and memory of D-galactose induced aging mice in a series of behavioral tests: novel-object recognition test, nest-building test, Morris water maze test and step-through test. Pharmacologic studies were conducted from several aspects: the cholinergic system, mitochondrial respiration, oxidative stress, neuroinflammation, apoptosis and synaptic loss. The acetylcholine level and AChE activity were not altered by D-galactose but were slightly affected by DL0410 in the brain. DL0410 could significantly improve decreased mitochondrial respiration in the NADH chain and FADH2 chain, and protect mitochondrial ultrastructure. DL0410 reduced the accumulation of advanced glycation end products (AGEs) and malondialdehyde (MDA) and increase the total antioxidant capability of the brain via an increase in activity of catalase, glutathione peroxidase (GPx) and superoxide dismutase (SOD). RAGE expression was inhibited by DL0410, followed by the decreased activation of astrocytes and microglia. Subsequent phosphorylation of NF-κB was also reversed by DL0410, with lower expression of cyclooxygenase-2 (COX2) and iNOS. With respect to apoptosis, the activation of caspase 3 and cleavage of PARP were downregulated significantly by DL0410, after the inhibition of phosphorylation of JNK induced by inflammation and oxidative stress. Synaptic protection by DL0410 was also demonstrated. These data suggest that mitochondrial protection has a primary role in the ameliorating effect of DL0410 on the impaired learning and memory, oxidative stress, inflammation, apoptosis and synaptic loss induced by D-galactose. DL0410 is a promising candidate for the treatment of aging-related AD, and this study lays an important foundation for its further research and development.

Protective effect of atorvastatin on d-galactose-induced aging model in mice

Atorvastatin (Ator), competitive inhibitors of 3-hydroxymethyl-3-glutaryl-coenzyme-A reductase, is a cholesterol lowering drug. Ator has been shown to have neuroprotective, antioxidant and anti-inflammatory properties making that a potential candidate for the treatment of central nervous system (CNS) disorders. Here we assessed the effect of Ator on the d-galactose (d-gal)-induced aging in mice. For this purpose, Ator (0.1 and 1mg/kg/p.o.), was administrated daily in d-gal-received (500mg/kg/p.o.) mice model of aging for six weeks. Anxiety-like behaviors and cognitive functions were evaluated by the elevated plus-maze and novel object recognition tasks, respectively. Physical power was assessed by forced swimming capacity test. Animals brains were analyzed for the superoxide dismutase (SOD) and brain-derived neurotrophic factor (BDNF). We found that Ator decreases the anxiety-like behaviors in d-gal-treated mice. Also, our behavioral tests showed that Ator reverses the d-gal induced learning and memory impairment. Furthermore, we found that Ator increases the physical power of d-gal-treated mice. Our results indicated that the neuroprotective effect of Ator on d-gal induced neurotoxicity is mediated, at least in part, by an increase in the SOD and BDNF levels. The results of present study suggest that Ator could be used as a novel therapeutic strategy for the treatment of age-related conditions.

H2S Donor NaHS Changes the Production of Endogenous H2S and NO in D-Galactose-Induced Accelerated Ageing

Aims. The study was designed to explore whether hydrogen sulphide (H₂S) and nitric oxide (NO) generation changed in D-galactose- (D-gal-) induced ageing, the possible effects of exogenous H₂S supplementation, and related mechanisms. Results. In D-gal-induced senescent mice, both H₂S and NO levels in the heart, liver, and kidney tissues were decreased significantly. A similar trend was observed in D-gal-challenged human umbilical vein endothelial cells (HUVECs). Sustained H₂S donor (NaHS) treatment for 2 months elevated H₂S and NO levels in these mice, and during this period, the D-gal-induced senescent phenotype was reversed. The protective effect of NaHS is associated with a decrease in reactive oxygen species levels and an increase in antioxidants, such as glutathione, and superoxide dismutase and glutathione peroxidase activities. Increased expression of the H₂S-producing enzymes cystathionine γ-lyase (CSE) and cystathionine-β-synthase (CBS) in the heart, liver, and kidney tissues was observed in the NaHS-treated groups. NaHS supplementation also significantly postponed D-gal-induced HUVEC senescence. Conclusions. Endogenous hydrogen sulphide production in both ageing mice and endothelial cells is insufficient. Exogenous H₂S can partially rescue ageing-related dysfunction by inducing endogenous H₂S and NO production and reducing oxidative stress. Restoring endogenous H₂S production may contribute to healthy ageing, and H₂S may have antiageing effects.

Milk, Fruit and Vegetable, and Total Antioxidant Intakes in Relation to Mortality Rates: Cohort Studies in Women and Men

High milk consumption might shorten life span through increased oxidative stress. We aimed to determine whether higher mortality rates with high milk consumption are modified by fruit and vegetable intake or total antioxidant intake (oxygen radical absorbance capacity). We used information from food frequency questionnaires completed by 61,420 women in a Swedish cohort (22,391 deaths from the 1987–1990 baseline onward), 36,714 women from a second survey (1997) of this cohort, and 45,280 Swedish men (15,478 deaths from the 1998 baseline onward). Compared with low consumption of milk (<1 glass/day) and high consumption of fruits/vegetables (≥5 servings/day), time-updated information revealed an adjusted hazard ratio for death of 2.79 (95% confidence interval (CI): 2.42, 3.21) in women who consumed ≥3 glasses of milk/day and <1 serving/day of fruit/vegetables and a hazard ratio of 1.60 (95% CI: 1.40, 1.82) in women who consumed the same amount of milk but ≥5 servings/day of fruits/vegetables. The same comparisons in men, based on a single food frequency questionnaire, displayed hazard ratios of 1.31 (95% CI: 1.14, 1.51) and 1.07 (95% CI: 0.97, 1.18), respectively. Total antioxidant consumption showed similar patterns as fruit/vegetable intakes. Dietary antioxidant intake, especially in women, seems to modify the elevated death rate associated with high milk consumption.

Protective effects of rambutan (Nephelium lappaceum) peel phenolics on H2O2-induced oxidative damages in HepG2 cells and d-galactose-induced aging mice

Rambutan peel phenolic (RPP) extracts were prepared via dynamic separation with macroporous resin. The total phenolic content and individual phenolics in RPP were determined. Results showed that the total phenolic content of RPP was 877.11 mg gallic acid equivalents (GAE)/g extract. The content of geranin (122.18 mg/g extract) was the highest among those of the 39 identified phenolic compounds. RPP protected against oxidative stress in H₂O₂-induced HepG2 cells in a dose-response manner. The inhibitory effects of RPP on cell apoptosis might be related to its inhibitory effects on the generation of intracellular reactive oxygen species and increased effects on superoxide dismutase activity. The in vivo anti-aging activity of RPP was evaluated using an aging mice model that was induced by d-galactose (d-gal). The results showed that RPP enhanced the antioxidative status of experimental mice. Moreover, histological analysis indicated that RPP effectively reduced d-gal-induced liver and kidney tissue damage in a dose-dependent manner. Therefore, RPP can be used as a natural antioxidant and anti-aging agent in the pharmaceutical and food industries.

Evidence of oxidative stress in brain and liver of young rats submitted to experimental galactosemia

Galactosemia is a disorder of galactose metabolism, leading to the accumulation of this carbohydrate. Galactosemic patients present brain and liver damage. For evaluated oxidative stress, 30-day-old males Wistar rats were divided into two groups: galactose group, that received a single injection of this carbohydrate (5 μmol/g), and control group, that received saline 0.9 % in the same conditions. One, twelve or twenty-four hours after the administration, animals were euthanized and cerebral cortex, cerebellum, and liver were isolated. After one hour, it was found a significant increase in TBA-RS levels, nitrate and nitrite and protein carbonyl contents in cerebral cortex, as well as protein carbonyl content in the cerebellum and in hepatic level of TBA-RS, and a significant decrease in nitrate and nitrite contents in cerebellum. TBA-RS levels were also found increased in all studied tissues, as well as nitrate and nitrite contents in cerebral cortex and cerebellum, that also present increased protein carbonyl content and impairments in the activity of antioxidant enzymes of rats euthanized at twelve hours. Finally, animals euthanized after twenty-four hours present an increase of TBA-RS levels in studied tissues, as well as the protein carbonyl content in cerebellum and liver. These animals also present an increased nitrate and nitrite content and impairment of antioxidant enzymes activities. Taken together, our data suggest that acute galactose administration impairs redox homeostasis in brain and liver of rats.