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

Deregulation of Neuroinflammatory and Neurotrophic Factors as Biological Events Triggered by D-Galactose Chronic Administration in Wistar Rats

The chronic administration of D-galactose (D-gal) is widely used to model brain senescence in rodents. However, the effects of prolonged oral exposure of D-gal on the neuroinflammatory cytokines in rats remain poorly characterized. Therefore, we administered D-gal (100 mg/kg) in male Wistar rats aged 3-4 months, via oral gavage once a day for 1, 2, 4, 6, or 8 weeks. Cytokine and neurotrophin levels were analyzed using the ELISA method. D-gal administrations for 4, 6, and 8 weeks significantly increased interleukin -1β (IL-1β), tumor necrosis factor-alpha (TNF-α), and interleukin-4 (IL-4) levels in the frontal cortex and hippocampus. In addition, 4, 6, and 8 weeks of D-gal administration significantly increased interleukin-10 (IL-10) levels in the frontal cortex; however, in the hippocampus, only 6 and 8 weeks of D-gal administration significantly increased the IL-10 levels. In terms of neurotrophin levels, our results demonstrated that 1 week of D-gal administration significantly increased Brain-derived Neurotrophic Factor (BDNF) and Nerve Growth Factor (NGF) in the hippocampus. In the frontal cortex, D-gal increased BDNF levels when administered for 1 and 2 weeks and increased NGF levels when administered for only 2 weeks. However, we observed a reduction of BDNF, NGF, and Glial cell line-derived Neurotrophic Factor (GDNF) levels after 6 and 8 weeks of D-gal treatment in the frontal cortex. Moreover, GDNF levels also were reduced after 4 weeks of D-gal administration. These findings suggest that oral D-gal exposure disrupts the balance of cytokines and neurotrophins, which may be an essential mechanism in brain aging and neurodegenerative processes.

17β-estradiol delays cardiac aging through suppressing the methylation of Beclin1 in a murine model

INTRODUCTION

Cardiac endogenous senescence will gradually change and aggravate with age. Recent research showed that 17β-estradiol (17β-E2), an estrogen with numerous biological activities including the prevention of vascular senescence. However, how 17β-E2 against cardiac aging is still unknown. This work addressed the underlying mechanism with regard to Beclin1 and autophagy activity to better understand the anti-senescent effect of 17β-E2 on a well-established animal model of cardiac aging.

MATERIAL AND METHODS

In this study, an aging model in female mice was established using d-galactose and ovariectomy. Cardiac function was evaluated by echocardiography, RNA-seq was performed to analyze the gene expression profiles of myocardial tissues from 17β-E2 treated mice. Additionally,The levels of Beclin1, LC3, P62, and ATG5 in myocardial tissues were assessed using qPCR and Western blotting. Methylation levels of the Beclin1 promoter region in myocardial tissues were determined by MSP and BSP.

RESULTS

The findings demonstrated that cardiac aging mice treated with 17β-E2 had improved heart function. 17β-E2 restored EF(increase 1.25-fold) and FS(increase 1.2-fold) to near-normal levels. By RNA-sequencing and Gene Set Enrichment Analysis (GSEA) analysis, the autophagy signaling pathway was further enriched in the myocardial tissue of cardiac aging mice treated with 17β-E2, and we also discovered that 17β-E2 suppress the methylation of Beclin1 promoter region, which mediate the activation of autophagy signal.

CONCLUSIONS

Overall, our data showed that 17β-E2's anti-senescent effect on cardiac aging mice was mediated by the crucial suppression of methylation in the Beclin1 promoter area and subsequent activation of the autophagy signal, which may present a possible therapeutic approach to prevent cardiac aging.

Characterization of microcirculatory endothelial functions in a D-Galactose-induced aging model

BACKGROUND

Microcirculation health is critical to human health, and aging is an important factor affecting microcirculation health. Although D-Galactose has been widely used in aging research models, there is a lack of relevant studies on D-Galactose simulating microcirculatory aging. Here, we explored microcirculatory endothelial function in D-Galactose-induced aging mice.

METHODS

Intraperitoneal injection of 150 mg/(kg·d) of D-Galactose was given to cause senescence in mice. Aging was evaluated by SA-β-gal (senescence-associated β-galactosidase) staining. The auricular skin and hepatic microcirculation of mice were observed and detected by enzyme-linked immunosorbent assay (ELISA), immunohistochemistry (IHC) and microcirculation apparatus. The aging of microcirculation was analyzed from oxidative stress, endothelial impairment, inflammation, microvascular morphology and hemodynamics.

RESULTS

In aging mice, percentage of SA-β-gal positive area, oxidative stress products reactive oxygen species (ROS) and nitric oxide (NO), endothelial impairment marker syndecan-1 (SDC-1), stromal cell derived factor-1 (SDF-1), intercellular cell adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) in the senescence-associated secretory phenotype (SASP) were all up-regulated. The tortuosity of microvessels increased in aging mice, the linear density did not change significantly, but the total length of narrow microvessels (TLNMV) increased and wide microvessels (TLWMV) decreased, speculate that vasomotor dysfunction may be present. Hemodynamically, both perfusion and velocity of blood flow were reduced in senescent mice, presumably due to endothelial dysfunction.

CONCLUSION

Microcirculatory endothelial dysfunction is induced by D-Galactose, leading to microcirculatory aging. In vivo, this is manifested by elevated levels of oxidative stress, impaired endothelial glycocalyx (eGC), and a greater production of chemokines and adhesive molecules. These changes cause vasomotor dysfunction and remodeling, ultimately leading to hemodynamic impairment.

Quercetin preserves mitochondria-endoplasmic reticulum contact sites improving mitochondrial dynamics in aged myocardial cells

Cardiomyocyte senescence plays a crucial role in the pathophysiology of age-related cardiovascular disease. Senescent cells with impaired contractility, mitochondrial dysfunction, and hypertrophic growth accumulate in the heart during aging, contributing to cardiac dysfunction and remodeling. Mitochondrial dynamics is altered in aging cells, leading to changes in their function and morphology. Such rearrangements can affect the spatially restricted region of the mitochondrial membrane that interacts with reticulum membrane fragments, termed mitochondria-endoplasmic reticulum (ER) contact sites (MERCs). Besides, oxidative stress associated with inefficient organelle turnover can drive cellular senescence. Therefore, in this study, we evaluated the possible association between the senolytic effect of the antioxidant quercetin (Q) and MERCs preservation in a D-galactose-induced cellular senescence model. We found that Q ameliorates the senescent phenotype of H9c2 cells in association with increased mitochondria-ER colocalization, reduced distance between both organelles, and lower ROS production. Moreover, regulation of fusion and fission processes was related with increased mitochondrial ATP production and enhanced transmembrane potential. Overall, our data provide evidence that the inhibitory effect of Q on cellular senescence is associated with preserved MERCs and improved mitochondrial function and morphology, which might contribute to the attenuation of cardiac dysfunction.

Aluminum chloride and D-galactose induced a zebrafish model of Alzheimer's disease with cognitive deficits and aging

Alzheimer's disease (AD) is an age-related neurodegenerative disorder. Transgenic and pharmacological AD models are extensively studied to understand AD mechanisms and drug discovery. However, they are time-consuming and relatively costly, which hinders the discovery of potential anti-AD therapeutics. Here, we established a new model of AD in larval zebrafish by co-treatment with aluminum chloride (AlCl3) and D-galactose (D-gal) for 72 h. In particular, exposure to 150 μM AlCl3 + 40 mg/mL D-gal, 200 μM AlCl3 + 30 mg/mL D-gal, or 200 μM AlCl3 + 40 mg/mL D-gal successfully induced AD-like symptoms and aging features. Co-treatment with AlCl3 and D-gal caused significant learning and memory deficits, as well as impaired response ability and locomotor capacity in the plus-maze and light/dark test. Moreover, increased acetylcholinesterase and β-galactosidase activities, β-amyloid 1-42 deposition, reduced telomerase activity, elevated interleukin 1 beta mRNA expression, and enhanced reactive oxygen species production were also observed. In conclusion, our zebrafish model is simple, rapid, effective and affordable, incorporating key features of AD and aging, thus may become a unique and powerful tool for high-throughput screening of anti-AD compounds in vivo.

Ferulic Acid-Loaded Nanostructure Maintains Brain Levels of ACh, Glutamate, and GABA and Ameliorates Anxiety and Memory Impairments Induced by the D-Galactose Aging Process in Rats

Population aging is a global reality driven by increased life expectancy. This demographic phenomenon is intrinsically linked to the epidemic of cognitive disorders such as dementia and Alzheimer's disease, posing challenges for elderly and their families. In this context, the search for new therapeutic strategies to prevent or minimize cognitive impairments becomes urgent, as these deficits are primarily associated with oxidative damage and increased neuroinflammation. Ferulic acid (FA), a natural and potent antioxidant compound, is proposed to be nanoencapsulated to target the central nervous system effectively with lower doses and an extended duration of action. Here, we evaluated the effects of the nanoencapsulated FA on d-galactose (d-Gal)- induced memory impairments. Male Wistar adult rats were treated with ferulic acid-loaded nanocapsules (FA-Nc) or non-encapsulated ferulic acid (D-FA) for 8 weeks concurrently with d-Gal (150 mg/kg s.c.) injection. As expected, our findings showed that d-Gal injection impaired memory processes and increased anxiety behavior, whereas FA-Nc treatment ameliorated these behavioral impairments associated with the aging process induced by d-Gal. At the molecular level, nanoencapsulated ferulic acid (FA-Nc) ameliorated the decrease in ACh and glutamate induced by d-galactose (d-Gal), and also increased GABA levels in the dorsal hippocampus, indicating its therapeutic superiority. Additional studies are needed to elucidate the mechanisms underlying our current promising outcomes. Nanoscience applied to pharmacology can reduce drug dosage, thereby minimizing adverse effects while enhancing therapeutic response, particularly in neurodegenerative diseases associated with aging. Therefore, the strategy of brain-targeted drug delivery through nanoencapsulation can be effective in mitigating aging-related factors that may lead to cognitive deficits.

Inhibition of 5-alpha reductase attenuates cardiac oxidative damage in obese and aging male rats via the enhancement of antioxidants and the p53 protein suppression

In aging and metabolic syndrome oxidative stress is a causative factor in the cardiovascular pathology. Upregulation of 5-⍺ reductase is associated with cardiac hypertrophy but how inhibition of 5-⍺ reductase affects cardiometabolic function during oxidative damage under those conditions is unclear. Our hypothesis was that Finasteride (Fin), a 5-⍺ reductase inhibitor, promotes an antioxidant response, leading to an improvement in cardiac function in obese and aging rats. Male rats were divided into 3 groups including normal diet (ND) fed rats, ND-fed rats treated with d-galactose (D-gal) to induce aging, and high-fat diet (HFD) fed rats to induce obesity. Rats received their assigned diet or D-gal for 18 weeks. At week 13, rats in each group were divided into 2 subgroups and received either a vehicle or Fin (5 mg/kg/day, oral gavage). Cardiometabolic and molecular parameters were subsequently investigated. Both D-gal and HFD successfully induced cardiometabolic dysfunction, oxidative stress, mitochondrial dysfunction, and DNA fragmentation. Fin treatment did not affect metabolic disturbances; however, it reduced cardiac sympathovagal imbalance, cardiac dysfunction through the inhibition of oxidative stress and promoted antioxidants, resulting in reduced p53 protein levels and DNA fragmentation. Surprisingly, Fin induced insulin resistance in ND-fed rats. Fin effectively improved cardiac function in both models by enhancing antioxidant levels, suppressing oxidative stress and DNA fragmentation. However, Fin treatment did not confer any beneficial effects on metabolic status. Fin administration effectively improved cardiac sympathovagal balance and cardiac function in rats with oxidative damage induced by either D-gal or HFD.

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.

Berberine attenuates brain aging via stabilizing redox homeostasis and inflammation in an accelerated senescence model of Wistar rats

Aging is a multifaceted and progressive physiological change of the organism categorized by the accumulation of deteriorating processes, which ultimately compromise the biological functions. The objective of this study was to investigate the anti-aging potential of berberine (BBR) in D-galactose (D-Gal) induced aging in rat models. In this study, male Wistar rats were divided into four groups: The control group was given only vehicle, the BBR group was treated with berberine orally, the D-Gal group was treated with D-galactose subcutaneously and the BBR + D-Gal group was treated with D-galactose and berberine simultaneously. D-galactose exposure elevated the pro-oxidants such as malondialdehyde (MDA) level, protein carbonyl and advanced oxidation protein products (AOPP) in the brain. It decreased the anti-oxidants such as reduced glutathione (GSH) and ferric reducing antioxidant potential (FRAP) in the brain. D-galactose treatment also reduced the mitochondrial complexes (I, II, III and IV) activities and elevated the inflammatory markers such as interleukine-6 (IL-6), tumor necrosis factor- α (TNF-α) and C-reactive protein (CRP). The mRNA expressions of IL-6 and TNF-α in the brain were upregulated following D-galactose exposure. Berberine co-treatment in D-galactose induced aging rat model prevented the alteration of pro-oxidant and anti-oxidant in the brain. Berberine treatment restored the mitochondrial complex activities in the brain and also normalized the inflammatory markers. Based on these findings we conclude that berberine treatment has the potential to mitigate brain aging in rats via stabilizing the redox equilibrium and neuroinflammation.

Future perspectives on the roles of mitochondrial dynamics in the heart in obesity and aging

Increasing global obesity rates and an aging population are independently linked to cardiac complications. Consequently, it is crucial to comprehensively understand the mechanisms behind these conditions to advance innovative therapies for age-related diseases. Mitochondrial dysfunction, specifically defects in mitochondrial fission/fusion processes, has emerged as a central regulator of cardiac complications in aging and age-related diseases (e.g., obesity). Since excessive fission and impaired fusion of cardiac mitochondria lead to disruptions in mitochondrial dynamics and cellular metabolism in aging and obesity, modulating mitochondrial dynamics with either fission inhibitors or fusion promoters has offered cardioprotection against these pathological conditions in preclinical models. This review explores the molecular mechanisms governing mitochondrial dynamics as well as the disturbances observed in aging and obesity. Additionally, pharmaceutical interventions that specifically target the processes of mitochondrial fission and fusion are presented and discussed. By establishing a connection between mitochondrial dynamism through fission and fusion and the advancement or mitigation of age-related diseases, particularly obesity, this review provides valuable insights into the progression and potential prevention strategies for such conditions.

Exercise and Caloric Restriction Exert Different Benefits on Skeletal Muscle Metabolism in Aging Condition

Exercise and caloric restriction improve skeletal muscle metabolism. However, the benefits of exercise and caloric restriction on skeletal muscle metabolism in aging have never been compared. Seven-week-old male Wistar rats (n = 24) were divided into 4 groups (n = 6 per group) to receive either normal saline solution for 28 weeks, 150 mg/kg/day of D-galactose for 28 weeks to induce premature aging, 150 mg/kg/day of D-galactose for 28 weeks plus exercise for 16 weeks (week 13-28), or 150 mg/kg/day of D-galactose for 28 weeks plus 30% caloric restriction for 16 weeks (week 13-28). The 17-month-old rats (n = 6) were also injected with normal saline solution for 28 weeks as the naturally aged controls. At the end of week 28, total walking distance and fatty acid and carbohydrate oxidation during physical activity were determined. Then, all rats were euthanized for the collection of blood and tibialis anterior muscle. The results showed that D-galactose successfully mimicked the natural aging of skeletal muscle. Exercise and caloric restriction equally improved carbohydrate oxidation during physical activity and myogenesis. However, exercise was superior to caloric restriction in terms of improving fatty acid oxidation and oxidative phosphorylation. Interestingly, caloric restriction decreased oxidative stress, whereas exercise increased oxidative stress of skeletal muscle. All of these findings indicated that the benefits of exercise and caloric restriction on skeletal muscle metabolism during aging were different, and therefore the combination of exercise and caloric restriction might provide greater efficacy in ameliorating skeletal muscle aging.

Long-term lifestyle intervention is superior to transient modification for neuroprotection in D-galactose-induced aging rats

AIMS

To investigate whether transient dietary restriction or aerobic exercise in young adulthood exert long-lasting protection against brain aging later in life.

MAIN METHODS

Seven-week-old male Wistar rats were divided into 2 groups and given either normal saline as a vehicle (n = 8) or 150 mg/kg/day of D-galactose (n = 40) for 28 weeks, the D-galactose being used to induce aging. At week 13 of the experiment, D-galactose-treated rats were further divided into 5 groups, 1) no intervention, 2) transient dietary restriction for 6 weeks (week 13-18), 3) transient exercise for 6 weeks (week 13-18), 4) long-term dietary restriction for 16 weeks (week 13-28), and 5) long-term exercise for 16 weeks (week 13-28). At the end of week 28, cognitive function was examined, followed by molecular studies in the hippocampus.

KEY FINDINGS

Our results showed that either long-term dietary restriction or aerobic exercise effectively attenuated cognitive function in D-galactose-treated rats via the attenuation of oxidative stress, cellular senescence, Alzheimer's-like pathology, neuroinflammation, and improvements in mitochondria, brain metabolism, adult neurogenesis, and synaptic integrity. Although transient interventions provided benefits in some brain parameters in D-galactose-treated rats, an improvement in cognitive function was not observed.

SIGNIFICANCE

Our findings suggested that transient lifestyle interventions failed to exert a long-lasting protective effect against brain aging. Hence, novel drugs mimicking the neuroprotective effect of long-term dietary restriction or exercise and the combination of the two since young age appear to be more appropriate treatments for the elderly who are unable to engage in long-term dietary restriction or exercise.