Animal Models Of Aging Research Articles

Flavonoids from Rhododendron nivale Hook. f ameliorate alcohol-associated liver disease via activating the PPARα signaling pathway

Background: Flavonoids are increasingly recognized for their potent antioxidant properties and potential therapeutic roles in the management of alcohol-associated liver disease (ALD). Extracts derived from Rhododendron nivale Hook. f. (FRN) have been shown to influence glutathione metabolism in aging animal models, exhibiting notable antioxidant effects. However, the specific impact of FRN on ALD remains insufficiently explored. Hypothesis/PurposeThis study seeks to elucidate the efficacy of FRN in alleviating the pathology associated with ALD, delving into the underlying molecular mechanisms that facilitate its protective effects. Study Design: We employed network pharmacology to predict the functional roles and pathway enrichments associated with FRN targets. Both a murine model of ALD and in vitro cellular models were utilized to clarify the mechanistic basis by which FRN mitigates ALD. Methods: FRN was extracted and characterized according to well-established methodologies outlined in our previous studies. Potential functions and pathways implicated by FRN were predicted through network pharmacology analyses. A combination of liver transcriptomics, targeted lipidomics, molecular biology techniques, and antagonists of relevant targets were employed to investigate the mechanisms through which FRN exerts its protective effects in ALD. Results: Network pharmacology identified multiple target genes modulated by FRN, particularly those within critical ALD-related signaling pathways, such as PPARα signaling and fatty acids (FAs) degradation. Notably, treatment with FRN in the ALD murine model led to a significant attenuation of hepatic lipid accumulation and a restoration of serum AST and ALT to baseline ranges. Subsequent validation through liver transcriptomics and molecular biology techniques revealed an upregulation of PPARα expression concomitant with a downregulation of ACSL1 in FRN-treated ALD mice. Targeted lipidomic and bioinformatic analyses from cellular assays demonstrated that FRN substantially reduced the accumulation of long-chain fatty acids in hepatocytes. Importantly, the reversal of FRN's protective effects on lipid accumulation through the PPARα antagonist GW6471 provides compelling evidence for the critical role of PPARα signaling modulation in mediating the beneficial impact of FRN on ALD. Conclusion: Our research highlights FRN's capacity to alleviate ALD through PPARα pathway activation, paving the way for innovative treatment strategies. This underscores the significance of natural compounds in pharmacotherapy, suggesting that FRN may provide an effective alternative for managing ALD.

Task-Based Eating and Drinking Interventions in Animal Models: A Narrative Review of Functional Improvements and Neuromuscular Adaptations in Age-Related Dysphagia.

Age-related dysphagia involves sarcopenia and nervous system changes affecting ingestion. The ACT-ING program, a novel task-based occupational therapy intervention, has been developed to improve strength, endurance, and ingestive skills using real-world eating and drinking tasks for older adults with age-related dysphagia. This narrative review evaluates the outcomes and neuromuscular adaptations of task-based eating and drinking interventions in aging animal models to inform potential refinements of the ACT-ING program and interpret results from an ongoing proof-of-concept study. Publications were obtained from PubMed, SCOPUS, CINAHL, and EMBASE, and selected following the PRISMA guideline. Thirteen randomized trials investigated a task-based fluid-licking intervention in rats, combining strength, endurance, and skill training. Results suggested benefits in improving muscle strength, endurance, and swallowing skills in terms of quantity and speed. Although neuromuscular adaptations were less conclusive, the intervention appeared to induce cortical plasticity and increase fatigue-resistant muscle fibers in the involved muscles. While these findings are promising, methodological concerns and potential biases were identified. Therefore, further research is necessary to refine the ACT-ING program, including both clinical studies in humans and preclinical studies in aging animal models that clearly define interventions targeting all aspects of ingestion-related skills within a motor learning and strength training framework.

Effects of Menopause and High Fat Diet on Metabolic Outcomes in a Mouse Model of Alzheimer's Disease.

About two-thirds of those with Alzheimer's disease (AD) are women, most of whom are post-menopausal. Menopause accelerates dementia risk by increasing the risk for metabolic, cardiovascular, and cerebrovascular diseases. Mid-life metabolic disease (obesity, diabetes/prediabetes) is a well-known risk factor for dementia. A high fat diet can lead to poor metabolic health in both humans and rodents. Our goal was to determine the effects of a high fat diet on metabolic outcomes in the AppNL-F knock-in mouse model of AD and assess the effects of menopause. First, 3-month-old AppNL-F and WT female mice were placed on either a control or a high fat diet until 10 months of age then assessed for metabolic outcomes. Next, we did a more extensive assessment in AppNL-F mice that were administered VCD (4-vinylcyclohexene diepoxide) or vehicle (oil) and placed on a control or high fat diet for 7 months. VCD was used to model menopause by causing accelerated ovarian failure. Compared to WT controls, AD female mice had worse glucose intolerance. Menopause led to metabolic impairment (weight gain and glucose intolerance) and further exacerbated obesity in response to a high fat diet. There were interactions between diet and menopause on some metabolic health serum biomarkers and the expression of hypothalamic markers related to energy balance. This work highlights the need to model endocrine aging in animal models of dementia and will contribute to further understanding the interaction between menopause and metabolic health in the context of AD.

Neurological Restorative Effects of (-)-Epicatechin in a Model of Gulf War Illness.

Gulf War Illness (GWI) afflicts US military personnel who served in the Persian Gulf War. Suspect causal agents include exposure to pyridostigmine (PB), permethrin (PM) and N,N-diethyl-m-toluamide (DEET). Prominent symptoms include cognitive deficits, such as memory impairment. In aging animal models, we have documented the beneficial effect of the flavanol (-)-epicatechin (Epi) on hippocampus structure and related function. Using a rat model of GWI, we examined the effects of Epi on hippocampus inflammation, oxidative stress, mitochondrial dysfunction, cell death/survival pathways, and memory endpoints. Male Wistar rats underwent 3 weeks of exposure to either vehicles or DEET, PM, PB, and stress. Subgroups of GWI rats were then allocated to receive orally 15 days of either water (vehicle) or 1 mg/kg/day of Epi treatment. Object recognition tasks were performed to assess memory. Hippocampus samples were analyzed. Epi treatment yields significant improvements in short- and long-term memory versus GWI rats. Hippocampus oxidative stress and pro-inflammatory cytokine levels showed significant increases with GWI that were largely normalized with Epi becoming comparable to controls. Significant increases in markers of hippocampus neuroinflammation and cell death were noted with GWI and were also largely reduced with Epi. Neuronal survival signaling pathways were adversely impacted by GWI and were partially or fully restored by Epi. Markers of mitochondrial function were adversely impacted by GWI and were fully restored by Epi. In conclusion, in an animal model of GWI, Epi beneficially impacts recognized markers of hippocampus neuroinflammation, oxidative stress, cell survival, neurotoxicity and mitochondrial function leading to improved memory.

Animal Models Relevant for Geroscience: Current Trends and Future Perspectives in Biomarkers, and Measures of Biological Aging.

For centuries, aging was considered inevitable and immutable. Geroscience provides the conceptual framework to shift this focus toward a new view that regards aging as an active biological process, and the biological age of an individual as a modifiable entity. Significant steps forward have been made toward the identification of biomarkers for and measures of biological age, yet knowledge gaps in geroscience are still numerous. Animal models of aging are the focus of this perspective, which discusses how experimental design can be optimized to inform and refine the development of translationally relevant measures and biomarkers of biological age. We provide recommendations to the field, including: the design of longitudinal studies in which subjects are deeply phenotyped via repeated multilevel behavioral/social/molecular assays; the need to consider sociobehavioral variables relevant for the species studied; and finally, the importance of assessing age of onset, severity of pathologies, and age-at-death. We highlight approaches to integrate biomarkers and measures of functional impairment using machine learning approaches designed to estimate biological age as well as to predict future health declines and mortality. We expect that advances in animal models of aging will be crucial for the future of translational geroscience but also for the next chapter of medicine.

Computational model for synthesizing auditory brainstem responses to assess neuronal alterations in aging and autistic animal models.

This study presents a novel computational model of the auditory brainstem, capable of synthesizing auditory brainstem response (ABR) traces by simulating large-scale neuronal activities. Addressing limitations of traditional ABR measurements, the model links ABR waveform features to underlying neuronal properties. Validated using empirical ABRs from animal models of autism and aging, the model accurately reproduced observed ABR alterations, revealing influences of myelin deficits and hyperexcitability in Fragile X syndrome, and degraded inhibitory activity in aging. These findings, supported by experimental data, demonstrate the model's potential for predicting changes in auditory brainstem physiology and guiding further physiological investigations, thus advancing our understanding of auditory neural processes.

Abstract Or117: JNK2-mediated gut-heart crosstalk in aging-associated AF pathogenesis.

Introduction: Aging is an independent risk factor for atrial fibrillation (AF). We recently revealed a critical role of activated cardiac stress kinase JNK2 in AF risk. Yet, the mechanisms underlying JNK2 activation in the aged heart remain unclear. Emerging evidence suggests that organ crosstalk critically contributes to the development of heart diseases. Interestingly, increased AF episodes were clinically observed in patients with active gastrointestinal (GI) diseases (with a hallmark of enhanced intestinal epithelial barrier permeability (‘leaky gut’), but reduced AF during remission. While both GI dysfunction and enhanced AF risk are seen in aged humans and animal models, whether aging-associated leaky gut leads to AF pathogenesis through activated JNK2 remains unknown. Methods: To assess the leaky gut and AF link, young (Yg, 2 mo) wildtype (WT) and JNK2dn mice (cardiac-specific overexpression of inactive dominant negative (dn) JNK2) were used for aged fecal matter transplant (FMT), while aged (Ag, 24 mo) mice were transplanted with Yg fecal matter to rescue aging-associated AF. Atrial tachycardia/fibrillation (AT/AF) incidence was measured using our well-established protocol, and GI permeability was measured using a serum dextran (4-kDa) FITC fluorescence assay 7 days post-FMT. Results: Aged WT mice had an elevated FITC level (4.9±1.5 µg/ml vs 0.98±0.04 µg/ml; n=11,8; p<0.01) with increased AT/AF inducibility compared to Yg mice (n=7,10; p<0.05). Interestingly, Yg WT recipients subjected to aged FMT (Ag-to-Yg) exhibited an ~3-fold increase in GI permeability (n=14; p<0.01) and significantly enhanced AT/AF inducibility relative to Yg sham controls (8 of 13 vs 0 of 10; p<0.05), while Yg-to-Yg FMT did not alter GI permeability and AT/AF inducibility in Yg recipients (0 of 5, p=NS). Strikingly, cardiac-specific JNK2 inhibition prevented aged-FMT-caused AT/AF in Yg JNK2dn recipient mice (0 of 10; p<0.01), suggesting that activated cardiac JNK2 underlies leaky gut-evoked AF in aging. Further, Yg-to-Ag FMT eliminated aged-associated AT/AF inducibility in aged recipients (0 of 6). Conclusion: Aging-associated GI dysfunction enhances cardiac JNK2 activation, which in turn drives AF risk. Targeting cardiac JNK2 could be a novel anti-AF therapeutic strategy.

Reactive oxygen-scavenging polydopamine nanoparticle coated 3D nanofibrous scaffolds for improved osteogenesis: Toward an aging in vivo bone regeneration model.

Tissue engineered scaffolds aimed at the repair of critical-sized bone defects lack adequate consideration for our aging society. Establishing an effective aged in vitro model that translates to animals is a significant unmet challenge. The in vivo aged environment is complex and highly nuanced, making it difficult to model in the context of bone repair. In this work, 3D nanofibrous scaffolds generated by the thermally-induced self-agglomeration (TISA) technique were functionalized with polydopamine nanoparticles (PD NPs) as a tool to improve drug binding capacity and scavenge reactive oxygen species (ROS), an excessive build-up that dampens the healing process in aged tissues. PD NPs were reduced by ascorbic acid (rPD) to further improve hydrogen peroxide (H2O2) scavenging capabilities, where we hypothesized that these functionalized scaffolds could rescue ROS-affected osteoblastic differentiation in vitro and improve new bone formation in an aged mouse model. rPDs demonstrated improved H2O2 scavenging activity compared to neat PD NPs, although both NP groups rescued the alkaline phosphatase activity (ALP) of MC3T3-E1 cells in presence of H2O2. Additionally, BMP2-induced osteogenic differentiation, both ALP and mineralization, was significantly improved in the presence of PD or rPD NPs on TISA scaffolds. While in vitro data showed favorable results aimed at improving osteogenic differentiation by PD or rPD NPs, in vivo studies did not note similar improvements in ectopic bone formation an aged model, suggesting that further nuance in material design is required to effectively translate to improved in vivo results in aged animal models.

A comparative assessment of age-related nicotinamide adenine dinucleotide phosphate-diaphorase positivity in the spinal cord and medulla oblongata of pigeons, rats, and mice.

Nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase (N-d) positive neurons have been extensively studied across various animals, and N-d neurodegenerative neurites have been detected in some aged animal models. However, detailed knowledge on N-d positivity and aging-related alterations in the spinal cord and medulla oblongata of pigeons is limited. In this study, we investigated N-d positivity and age-related changes in the pigeon's spinal cord and medulla oblongata and compared them to those in rats and mice. Pigeons, had more N-d neurons in the dorsal horn, around the central canal, and in the column of Terni in the thoracic and lumbar segments, with scattered neurons found in the ventral horn of the spinal segments. N-d neurons were also present in the white matter of the spinal cord. Morphometric analysis revealed that the size of N-d soma in the lumbosacral, cervical, and thoracic regions was substantially altered in aged pigeons compared to young birds. Furthermore, the lumbar to sacral segments underwent significant morphological alterations. The main findings of this study were the presence of age-related N-d positive bodies (ANB) in aged pigeons, predominantly in the external cuneate nucleus (CuE) and occasionally in the gracilis and CuEs. ANBs were also identified in the gracile nuclei and spinal cord in the aged rats and mice, whereas in aged rats, ANBs were detected in the CuE spinal nucleus. Immunohistochemistry showed that the age-related alterations occurred in the cell types and neuropeptides in old animals. The results suggest weak inflammatory response and neuronal dysfunction in the spinal cord in aged pigeons. Our results suggested that the ANB could be a potential aging marker for the central nervous system.

Study on the molecular mechanisms of Liuwei Dihuang decoction against aging-related cognitive impairment based on network pharmacology and experimental verification

ObjectiveBased on network pharmacology and experimental validation, this study aimed to screen the potential targets of Liuwei Dihuang decoction (LW) against mild cognitive impairment (MCI). MethodsBased on network pharmacology, this study preliminarily explored the targets and molecular mechanisms of LW in the treatment of MCI. The results showed that the mechanism of action of LW against MCI may be related to the cAMP pathway. Then, an aging cell and animal model was established to further verify its molecular mechanism. ResultsA total of 23 active ingredients were identified in LW. In addition, through network pharmacological analysis, we found 22 anti-MCI active ingredients in LW, of which alisol B had the most significant effect, and predicted the potential mechanism pathway by which LW may improve MCI through the cAMP signaling pathway. Further in vivo and in vitro experiments confirmed that LW can alleviate cognitive dysfunction in aging mice and reduce D-galactose-induced senescent cells, which may be through activation of the cAMP/PKA/CREB signaling pathway. ConclusionThis study found that the traditional Chinese medicine formula LW may play a role in improving MCI by regulating the cAMP/PKA/CREB signaling pathway, which provides a reference for further clinical research on the anti-MCI effect of LW and its molecular mechanism.

Ganoderma tsuage promotes pain sensitivity in aging mice

Advances in modern medicine have extended human life expectancy, leading to a world with a gradually aging society. Aging refers to a natural decline in the physiological functions of a species over time, such as reduced pain sensitivity and reaction speed. Healthy-level physiological pain serves as a warning signal to the body, helping to avoid noxious stimuli. Physiological pain sensitivity gradually decreases in the elderly, increasing the risk of injury. Therefore, geriatric health care receives growing attention, potentially improving the health status and life quality of the elderly, further reducing medical burden. Health food is a geriatric healthcare choice for the elderly with Ganoderma tsuage (GT), a Reishi type, as the main product in the market. GT contains polysaccharides, triterpenoids, adenosine, immunoregulatory proteins, and other components, including anticancer, blood sugar regulating, antioxidation, antibacterial, antivirus, and liver and stomach damage protective agents. However, its pain perception-related effects remain elusive. This study thus aimed at addressing whether GT could prevent pain sensitivity reduction in the elderly. We used a galactose-induced animal model for aging to evaluate whether GT could maintain pain sensitivity in aging mice undergoing formalin pain test, hot water test, and tail flexes. Our results demonstrated that GT significantly improved the sensitivity and reaction speed to pain in the hot water, hot plate, and formalin tests compared with the control. Therefore, our animal study positions GT as a promising compound for pain sensitivity maintenance during aging.

Deletion of Myostatin Significantly and Preferentially Improves Muscle Function in a Sex-Dependent Manner in Both an Obese and Aging Mouse Model

Skeletal muscle mass and function are essential components of health and homeostasis. In addition to its role in balance and locomotion, skeletal muscle is the body’s largest metabolic reservoir, absorbing significant amounts of glucose and amino acids from the blood stream. The loss of muscle mass is associated with impaired glucose tolerance, threatens vascular health and contributes to cardiovascular disease in obese and aging (sarcopenic) populations, along with driving overall mortality. The myokine myostatin (GDF-8) is a potent negative regulator of skeletal muscle growth that is upregulated in humans and animal models of obesity and aging. Loss of myostatin is known to increase the number of glycolytic muscle fibers and has been shown to correct indices that govern cardiometabolic health in obesity and aging, improving endothelial function and glucose homeostasis, and protecting against renal injury and hypertension. However, these studies have largely been conducted using male mice, leaving the question regarding the effectiveness of myostatin deletion on skeletal muscle function, independent of sex, largely unexplored. As such, our hypothesis is that the deletion of myostatin will improve skeletal muscle function in both male and female mice, regardless of the disease phenotype being obesity or aging. Young (3-5 mo.) lean and obese mice were used, along with aged (18-24 mo.) mice. The obese db/db model was utilized as it is a well characterized model of hyperphagia that results in obesity and subsequent metabolic disease, including significant whole-body adiposity and reduced muscle mass. On this background we have crossed mice harboring constitutive genetic deletion of myostatin to reverse muscle loss. Thus, myostatin deletion was crossed onto the relevant backgrounds in combination with aging or obesity and included both sexes. Muscle function was assessed in all groups using in vivo plantarflexion. Young male mice demonstrated an ~20% increase in force production compared to the females. Results show that aging and obesity inhibited skeletal muscle function in both sexes, with female mice showing a lessened impact of obesity or aging. Myostatin deletion improved muscle function in male mice, returning both obesity-derived weakness and aging-induced sarcopenia back to levels of young control. However, female mice without myostatin experienced a relative gain-of-function, with force production significantly exceeding that of the young control. The implication of these results is that weight loss may be more effective in protecting muscle function in diseases in the male population whereas myostatin inhibition, either pharmaceutically or with prescription exercise, may result in greater improvements in the female sex comparatively. This research gratefully acknowledges support from the NIA (K01 AG064121), OCAST (HR21-045-1) and the Niblack Research Scholars Program. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

High-fat diet induces sarcopenic obesity in natural aging rats through the gut–trimethylamine N-oxide–muscle axis

IntroductionThe lack of suitable animal models for sarcopenic obesity (SO) limits in-depth research into the disease. Emerging studies have demonstrated that gut dysbiosis is involved in the development of SO. As the importance of microbial metabolites is starting to unveil, it is necessary to comprehend the specific metabolites associated with gut microbiota and SO. ObjectivesWe aimed to investigate whether high-fat diet (HFD) causes SO in natural aging animal models and specific microbial metabolites that are involved in linking HFD and SO. MethodsYoung rats received HFD or control diet for 80 weeks, and obesity-related metabolic disorders and sarcopenia were measured. 16S rRNA sequencing and non-targeted and targeted metabolomics methods were used to detect fecal gut microbiota and serum metabolites. Gut barrier function was evaluated by intestinal barrier integrity and intestinal permeability. Trimethylamine N-oxide (TMAO) treatment was further conducted for verification. ResultsHFD resulted in body weight gain, dyslipidemia, impaired glucose tolerance, insulin resistance, and systemic inflammation in natural aging rats. HFD also caused decreases in muscle mass, strength, function, and fiber cross-sectional area and increase in muscle fatty infiltration in natural aging rats. 16S rRNA sequencing and nontargeted and targeted metabolomics analysis indicated that HFD contributed to gut dysbiosis, mainly characterized by increases in deleterious bacteria and TMAO. HFD destroyed intestinal barrier integrity and increased intestinal permeability, as evaluated by reducing levels of colonic mucin-2, tight junction proteins, goblet cells and elevating serum level of fluorescein isothiocyanate-dextran 4. Correlation analysis showed a positive association between TMAO and SO. In addition, TMAO treatment aggravated the development of SO in HFD-fed aged rats through regulating the ROS-AKT/mTOR signaling pathway. ConclusionHFD leads to SO in natural aging rats, partially through the gut–microbiota–TMAO–muscle axis.

Impact of visceral adipose tissue on longevity and metabolic health: a comparative study of gene expression in perirenal and epididymal fat of Ames dwarf mice.

Emerging research underscores the pivotal role of adipose tissue in regulating systemic aging processes, particularly when viewed through the lens of the endocrine hypotheses of aging. This study delves into the unique adipose characteristics in an important animal model of aging - the long-lived Ames dwarf (df/df) mice. Characterized by a Prop1df gene mutation, these mice exhibit a deficiency in growth hormone (GH), prolactin, and TSH, alongside extremely low circulating IGF-1 levels. Intriguingly, while surgical removal of visceral fat (VFR) enhances insulin sensitivity in normal mice, it paradoxically increases insulin resistance in Ames dwarfs. This suggests an altered profile of factors produced in visceral fat in the absence of GH, indicating a unique interplay between adipose tissue function and hormonal influences in these models. Our aim was to analyze the gene expression related to lipid and glucose metabolism, insulin pathways, inflammation, thermoregulation, mitochondrial biogenesis, and epigenetic regulation in the visceral (perirenal and epididymal) adipose tissue of Ames dwarf and normal mice. Our findings reveal an upregulation in the expression of key genes such as Lpl, Adrβ3, Rstn, Foxo1, Foxo3a, Irs1, Cfd, Aldh2, Il6, Tnfα, Pgc1α, Ucp2, and Ezh2 in perirenal and Akt1, Foxo3a, PI3k, Ir, Acly, Il6, Ring1a, and Ring 1b in epididymal fat in df/df mice. These results suggest that the longevity phenotype in Ames dwarfs, which is determined by peripubertal GH/IGF-1 levels, may also involve epigenetic reprogramming of adipose tissue influenced by hormonal changes. The increased expression of genes involved in metabolic regulation, tumor suppression, mitochondrial biogenesis, and insulin pathways in Ames dwarf mice highlights potentially beneficial aspects of this model, opening new avenues for understanding the molecular underpinnings of longevity and aging.

Age-related increase in the expression of 11β-hydroxysteroid dehydrogenase type 1 in the hippocampus of male rhesus macaques.

The hippocampus is especially susceptible to age-associated neuronal pathologies, and there is concern that the age-associated rise in cortisol secretion from the adrenal gland may contribute to their etiology. Furthermore, because 11β-hydroxysteroid dehydrogenase type 1 (HSD11B1) catalyzes the reduction of cortisone to the active hormone cortisol, it is plausible that an increase in the expression of this enzyme enhances the deleterious impact of cortisol in the hippocampus and contributes to the neuronal pathologies that underlie cognitive decline in the elderly. Rhesus macaques were used as a translational animal model of human aging, to examine age-related changes in gene and protein expressions of (HSD11B1/HSD11B1) in the hippocampus, a region of the brain that plays a crucial role in learning and memory. Older animals showed significantly (p < 0.01) higher base-line cortisol levels in the circulation. In addition, they showed significantly (p < 0.05) higher hippocampal expression of HSD11B1 but not NR3C1 and NR3C2 (i.e., two receptor-encoding genes through which cortisol exerts its physiological actions). A similar age-related significant (p < 0.05) increase in the expression of the HSD11B1 was revealed at the protein level by western blot analysis. The data suggest that an age-related increase in the expression of hippocampal HSD11B1 is likely to raise cortisol concentrations in this cognitive brain area, and thereby contribute to the etiology of neuropathologies that ultimately lead to neuronal loss and dementia. Targeting this enzyme pharmacologically may help to reduce the negative impact of elevated cortisol concentrations within glucocorticoid-sensitive brain areas and thereby afford neuronal protection.

First International Conference on Unconventional Animal Models of Alzheimer's Disease and Aging.

The first International Conference on Unconventional Animal Models of Alzheimer's Disease and Aging (UAMAA) took place on December 13-16, 2023, in Santiago, Chile. The Alzheimer's disease (AD) research field is currently in search for new and unconventional models that could hold greater translational potential than transgenic mouse models. Thus this UAMAA conference is timely and significant. The event consisted of 6 sessions with talks from 28 world-class scientists from all over the world. These animal models of interest include the degu (Octodon degu), the dog (Canis familiaris), and certain species of nonhuman primates that may better recapitulate neuropathology and cognitive impairments in human AD. Our conference has provided a formal forum to discuss and highlight new research directions, alternative animal models, and innovative approaches for the AD and aging research field.

Cellular senescence and nanoparticle-based therapies: Current developments and perspectives

Abstract The timing and location of senescent cells in vivo is a leading candidate explanation for human aging. A rapidly developing scientific field with the potential to slow the aging process is the creation of pharmacologically active medicines that target senescent cells. Senotherapeutics have been developed to selectively or preferentially target and eliminate senescent cells. Senolytic compounds that delay aging in animal models are being explored in humans with great hope. Nanoparticle (NP) drug delivery strategies for targeting senescent cells are in their infancy, but advancements have been made, and preliminary anti-aging applications are promising. However, using nanomedicine effectively requires an understanding of how NPs behave in senescent cells. Senescence theranostics could offer a variety of information, including a prognostic predictor in cancer patients after treatment. The NPs have a much better outlook for translating it to the clinic for aging. Reversing aging pathologies may only require a percentage reduction in senescent cells to achieve therapeutic success, in contrast to cancer, where it is essential to eradicate the tumor. This review provides an overview of the factors that lead to senescence and different therapeutic approaches, focusing on the use of nanocarriers/particles in senotherapy.

Microbial dysbiosis and the aging process: a review on the potential age-deceleration role of Lactiplantibacillus plantarum.

Gut microbiota dysbiosis has been a serious risk factor for several gastric and systemic diseases. Recently, gut microbiota's role in aging was discussed. Available preclinical evidence suggests that the probiotic bacteria Lactiplantibacillus plantarums (LP) may influence the aging process via modulation of the gut microbiota. The present review summarized compelling evidence of LP's potential effect on aging hallmarks such as oxidative stress, inflammation, DNA methylation, and mitochondrial dysfunction. LP gavage modulates gut microbiota and improves overall endurance in aging animal models. LP cell constituents exert considerable antioxidant potential which may reduce ROS levels directly. In addition, restored gut microbiota facilitate a healthy intestinal milieu and accelerate multi-channel communication via signaling factors such as SCFA and GABA. Signaling factors further activate specific transcription factor Nrf2 in order to reduce oxidative damage. Nrf2 regulates cellular defense systems involving anti-inflammatory cytokines, MMPs, and protective enzymes against MAPKs. We concluded that LP supplementation may be an effective approach to managing aging and associated health risks.

Insulin Ameliorates Neurodegeneration in an Experimental Animal Model of Brain Aging by a Decrease of GFAP Expression and Apoptosis Inhibition

Background: Aging is one of the factors that will cause gradual changes in brain tissue and its destruction. One of the protective factors against aging is insulin. Objectives: Our study investigated insulin's neuroprotective effect by preventing oxidative stress-mediated neuronal damage. Methods: A total of 48 adult male NMRI (the Naval Medical Research Institute) mice were divided into 2 groups: Control and insulin. Insulin was administered intraperitoneally (IP) for 8 weeks to the control group and for 12 weeks to the insulin group. In this study, animals were treated with insulin, and insulin's role in the aging process was evaluated. Then, brain tissue was extracted for evaluation of oxidative stress by assessment of glutathione disulfide (GSH) and reactive oxygen species (ROS) levels, the expression of the glial fibrillary acidic protein (GFAP) as a biomarker for astrogliosis, stereological study, and the real-time polymerase chain reaction (PCR) technique evaluated the level of apoptosis biomarker. Results: The results of stereological parameters show that the volumes of the brain cortex and the number of neurons improved in the insulin group by aging as compared to the control group. The results of real-time PCR showed that the expression level of apoptotic markers decreased in the insulin group compared to the control group. In the insulin group, GSH levels were higher than in the control group, and the control group produced more ROS than the insulin group. As compared with insulin, the control group expressed more GFAP protein and increased the number of glial cells by aging. Conclusions: The results showed that insulin could have neuroprotective effects against aging changes and reduce apoptosis and cell death.

Restoration of norepinephrine release, cognitive performance, and dendritic spines by amphetamine in aged rat brain.

Age-related dysfunctions in specific neurotransmitter systems likely play an important role in cognitive decline even in its most subtle forms. Therefore, preservation or improvement of cognition via augmentation of neurotransmission is a potential therapeutic strategy to prevent further cognitive deficits. Here we identified a particular neuronal vulnerability in the aged Fischer 344 rat brain, an animal model of neurocognitive aging. Specifically, we demonstrated a marked impairment in glutamate-stimulated release of norepinephrine (NE) in the hippocampus and cerebral cortex of aged rats, and established that this release was mediated by N-methyl-D-aspartate (NMDA) receptors. Further, we also demonstrated that this decrease in NE release is fully rescued by the psychostimulant drug amphetamine (AMPH). Moreover, we showed that AMPH increases dendritic spine maturation, and importantly shows preclinical efficacy in restoring memory deficits in the aged rat through its actions to potentiate NE neurotransmission at β-adrenergic receptors. Taken together, our results suggest that deficits in glutamate-stimulated release of NE may contribute to and possibly be a determinant of neuronal vulnerability underlying cognitive decline during aging, and that these deficits can be corrected with currently available drugs. Overall these studies suggest that repurposing of psychostimulants for age-associated cognitive deficits is a potential avenue to delay or prevent cognitive decline and/or frank dementia later in life.