Senescence-accelerated Resistant Mice Research Articles

Multi-strain probiotics ameliorate Alzheimer’s-like cognitive impairment and pathological changes through the AKT/GSK-3β pathway in senescence-accelerated mouse prone 8 mice

BackgroundAlzheimer’s disease (AD), the most prevalent type of dementia, still lacks disease-modifying treatment strategies. Recent evidence indicates that maintaining gut microbiota homeostasis plays a crucial role in AD. Targeted regulation of gut microbiota, including probiotics, is anticipated to emerge as a potential approach for AD treatment. However, the efficacy and mechanism of multi-strain probiotics treatment in AD remain unclear. MethodsIn this study, 6-month-old senescence-accelerated-mouse-prone 8 (SAMP8) and senescence-accelerated-mouse-resistant 1 (SAMR1) were utilized. The SAMP8 mice were treated with probiotic-2 (P2, a probiotic mixture of Bifidobacterium lactis and Lactobacillus rhamnosus) and probiotic-3 (P3, a probiotic mixture of Bifidobacterium lactis, Lactobacillus acidophilus, and Lactobacillus rhamnosus) (1 × 109 colony-forming units) once daily for 8 weeks. Morris water maze (MWM) and novel object recognition (NOR) tests were employed to assess the memory ability. 16S sequencing was applied to determine the composition of gut microbiota, along with detecting serum short-chain fatty acids (SCFAs) concentrations. Neural injury, Aβ and Tau pathology, and neuroinflammation level were assessed through western blot and immunofluorescence. Finally, potential molecular mechanisms was explored through transcriptomic analysis and western blotting. ResultsThe MWM and NOR test results indicated a significant improvement in the cognitive level of SAMP8 mice treated with P2 and P3 probiotics compared to the SAMP8 control group. Fecal 16S sequencing revealed an evident difference in the α diversity index between SAMP8 and SAMR1 mice, while the α diversity of SAMP8 mice remained unchanged after P2 and P3 treatment. At the genus level, the relative abundance of ten bacteria differed significantly among the four groups. Multi-strain probiotics treatment could modulate serum SCFAs (valeric acid, isovaleric acid, and hexanoic acid) concentration. Neuropathological results demonstrated a substantial decrease in neural injury, Aβ and Tau pathology and neuroinflammation in the brain of SAMP8 mice treated with P3 and P2. Transcriptomic analysis identified the chemokine signaling pathway as the most significantly enriched signaling pathway between SAMP8 and SAMR1 mice. Western blot test indicated a significant change in the phosphorylation level of downstream AKT/GSK-3β between the SAMP8 and SAMR1 groups, which could be reversed through P2 and P3 treatment. ConclusionsMulti-strain probiotics treatment can ameliorate cognitive impairment and pathological change in SAMP8 mice, including neural damage, Aβ and Tau pathology, and neuroinflammation. This effect is associated with the regulation of the phosphorylation of the AKT/GSK-3β pathway.

Xixin Decoction regulates Th17/Treg balance and transcription factor expression in senescence-accelerated mouse-prone

This study aims to investigate the effect of Xixin Decoction on the T helper 17 cell(Th17)/regulatory T cell(Treg) ba-lance of intestinal mucosa and the expression of related transcription factors in the senescence-accelerated mouse-prone 8(SAMP8) model. Fifty 14-week male mice of SAMP8 were randomized by the random number table method into model group, probiotics group, and high-, medium-, and low-dose Xixin Decoction groups, with 10 mice in each group. Ten 14-week male mice of senescence-acce-lerated mouse-resistant 1(SAMR1) served as control group. After 10 weeks of feeding, the mice were administrated with correspon-ding drugs for 10 weeks. Morris water maze test was carried out to examine the learning and memory abilities of mice. Enzyme-linked immunosorbent assay(ELISA) was employed to determine the content of secretory immunoglobulin A(SIgA) in the intestinal mucosa, and flow cytometry to detect the percentage content of Th17 and Treg in the intestinal mucosa. Western blot was performed to determine the protein levels of retinoid-related orphan receptor gamma t(RORγt) and forkhead box p3(Foxp3) in the mouse colon tissue. Compared with control group, the escape latency of mice in model group was significantly prolonged(P<0.01), and the number of times of crossing the platform and the residence time in the target quadrant were significantly reduced within 60 s(P<0.01), intestinal mucosal SIgA content was significantly decreased(P<0.01), Th17 content was increased(P<0.05), Treg content was decreased(P<0.01), the expression of RORγt protein was increased and Foxp3 protein was decreased in colon(P<0.01). Compared with the model group, high-dose Xixin Decoction group improved the learning and memory ability(P<0.05 or P<0.01). Probiotics group and high-and medium-dose Xixin Decoction group increased the content of SIgA in intestinal mucosa(P<0.05 or P<0.01), decreased percentage content of Th17 and increased the percentage content of Treg in intestinal mucosa(P<0.05 or P<0.01). Furthermore, they down-regulated the protein level of RORγt and up-regulated the protein level of Foxp3 in the intestinal mucosa(P<0.01). In conclusion, Xixin Decoction may act on intestinal mucosal immune barrier, affect gut-brain information exchange, and improve the learning and memory ability of SAMP8 by promoting SIgA secretion and regulating the Th17/Treg balance and the expression of RORγt and Foxp3.

Exogenous Nucleotides Ameliorate Age-Related Decline in Testosterone in Male Senescence-Accelerated Mouse Prone-8 (SAMP8) Mice by Modulating the Local Renin-Angiotensin System Antioxidant Pathway.

In older men, an age-related decline in testosterone is closely associated with various adverse health outcomes. With the progression of aging, hyperactivation of the local renin-angiotensin system (RAS) and oxidative stress increase in the testis. The regulation of RAS antioxidants may be a target to delay testicular aging and maintain testosterone levels. Exogenous nucleotides (NTs) have anti-aging potential in several systems, but there are no studies of their effects on the reproductive system. In our study, we examined the effects of exogenous NTs on testosterone synthesis and explored possible mechanisms of action. Therefore, senescence-accelerated mouse prone-8 (SAMP8) mice and senescence-accelerated mouse resistant 1 (SAMR1) were used in the experiment, and they were randomly divided into an NTs free group (NTs-F), a normal control group (control), a low-dose NTs group (NTs-L), a middle-dose NTs (NTs-M), a high-dose NTs group (NTs-H) and SAMR1 groups, and the testis of the mice were collected for testing after 9 months of intervention. The results showed that exogenous NTs could increase the testicular organ index in mice during aging, and delayed the age-associated decline in testosterone levels in SAMP8 male mice, possibly by modulating the local RAS antioxidant pathway and reducing oxidative stress to protect the testis. The present study provides new research clues for the development of preventive and therapeutic strategies for related diseases.

Xixin Decoction improves learning and memory ability of SAMP8 by enhancing neuroprotective effect and inhibiting neuroinflammation

This study aimed to explore the possible effect of Xixin Decoction(XXD) on the learning and memory ability of Alzheimer's disease(AD) model senescence-accelerated mouse-prone 8(SAMP8) and the related mechanism in enhancing neuroprotective effect and reducing neuroinflammation. Forty SAMP8 were randomly divided into a model group(10 mL·kg~(-1)·d~(-1)), a probiotics group(0.39 g·kg~(-1)·d~(-1)), a high-dose group of XXD granules(H-XXD, 5.07 g·kg~(-1)·d~(-1)), a medium-dose group of XXD granules(M-XXD, 2.535 g·kg~(-1)·d~(-1)), and a low-dose group of XXD granules(L-XXD, 1.267 5 g·kg~(-1)·d~(-1)). Eight senescence-accelerated mouse-resistant 1(SAMR1) of the same age and strain were assigned to the control group(10 mL·kg~(-1)·d~(-1)). After ten weeks of intragastric administration, the Morris water maze was used to test the changes in spatial learning and memory ability of mice after treatment. Meanwhile, immunofluorescence staining was used to detect the positive expression of receptor for advanced glycation end products(AGER), Toll-like receptor 1(TLR1), and Toll-like receptor 2(TLR2) in the hippocampal CA1 region of mice. Western blot was employed to test the protein expression levels of silencing information regulator 2 related enzyme 1(SIRT1), AGER, TLR1, and TLR2 in the hippocampus of mice. Enzyme linked immunosorbent assay(ELISA) was applied to assess the levels of Aβ_(1-42) in the hippocampus of mice and the levels of nuclear factor κB p65(NF-κB p65), NOD-like receptor protein 3(NLRP3), tumor necrosis factor-α(TNF-α), and interleukin-1β(IL-1β) in the serum and hippocampus of mice. Compared with the model group, XXD significantly improved the spatial learning and memory ability of SAMP8, increased the expression of neuroprotective factors in the hippocampus, decreased the levels of neuroinflammatory factors, and inhibited the expression of Aβ_(1-42). In particular, H-XXD significantly increased the expression of SIRT1 in the hippocampus of mice, reduced the expression levels of NF-κB p65, NLRP3, TNF-α, and IL-1β in the serum and hippocampus of mice, and decreased the expression of AGER, TLR1, and TLR2 in the hippocampus of mice(P<0.05 or P<0.01). XXD may improve the spatial learning and memory ability of AD model SAMP8 by enhancing the neuroprotective effect and inhibiting neuroinflammation.

Exogenous Nucleotides Ameliorate Ageing-Related Intestinal Inflammation in Senescence-Accelerated Mouse Prone-8 (SAMP8) Mice.

As one of the most important barriers in the body, the intestinal barrier is a key factor in maintaining human health. Ageing of the intestine is a degenerative process that is closely associated with a variety of poor health conditions in the elderly. Inflammation and the immune system are anti-ageing targets that can regulate the function of the intestine. Nucleotides (NTs) are involved in important physiological and biochemical reactions in the body, but there are few studies about their effect on the ageing intestine. This paper examines the role of exogenous NTs in the ageing intestine. For this purpose, we used senescence-accelerated mouse prone-8 (SAMP8) mice and senescence-accelerated mouse resistant 1 (SAMR1) mice for the experiment, and randomly divided the mice into NTs-free, Normal Control, NTs-low, NTs-medium, NTs-high, and SAMR1 groups. After 9 months of intervention, we collected the colon tissue of mice for testing. In our study, exogenous NTs could increase bodyweight of mice during ageing and improve the morphological structure of the intestine, and we found that NTs could promote the secretion of intestinal protective factors, such as TFF3 and TE. Furthermore, supplementation with NTs suppressed intestinal inflammation and improved intestinal immunity, possibly by activating the p38 signaling pathway. These results suggest that exogenous NTs are able to maintain the health condition of the ageing intestine.

Proteomic analysis of anti-aging effects of Dendrobium nobile Lindl. alkaloids in aging-accelerated SAMP8 mice

Senescence-accelerated mouse prone 8 (SAMP8) mice exhibit cognitive defects and neuron loss with aging, and were used to study anti-aging effects of Dendrobium nobile alkaloids (DNLA). DNLA (20 and 40 mg/kg) were orally administered to SAMP8 mice from 6 to 10 months of age. At 10-month of age, behavioral tests via Y-maze and Open-field and neuron damage via Nissl staining were evaluated. Protein was extracted and subjected to phosphorylated proteomic analysis followed by bioinformatic analysis. The cognitive deficits and neuron loss in hippocampus and cortex of aged SAMP8 mice were improved by DNLA. Hippocampal proteomic analysis revealed 196 differentially expressed protein/genes in SAMP8 compared to age-matched senescence-accelerated resistant SAMR1 mice. Gene Oncology enriched the tubulin binding, microtubule binding, and other activities. Kyoto Encyclopedia of Genes and Genomes (KEGG) revealed endocytosis, mRNA surveillance, tight junction, protein processing in endoplasmic reticulum, aldosterone synthesis and secretion, and glucagon signaling pathway changes. Upregulated protein/genes in the hippocampus of SAMP8 mice, such as Lmtk3, Usp10, Dzip1, Csnk2b, and Rtn1, were attenuated by DNLA; whereas downregulated protein/genes, such as Kctd16, Psd3, Bsn, Atxn2l, and Kif1a, were rescued by DNLA. The aberrant protein/gene expressions of SAMP8 mice were correlated with transcriptome changes of Alzheimer's disease in the Gene Expression Omnibus (GEO) database, and the scores were attenuated by DNLA. Thus, DNLA improved cognitive dysfunction and ameliorated neuronal injury in aged SAMP8 mice, and attenuated aberrant protein/gene expressions.

ANTI-RANKL TREATMENT ENHANCES MUSCLE STRENGTH THROUGH MACROPHAGE MODULATION MECHANISM IN SARCOPENIC MICE

Sarcopenia is an age-related geriatric syndrome which is associated with subsequent disability and morbidity. Currently there is no promising therapy approved for the treatment of sarcopenia. The receptor activator of nuclear factor NF-κB ligand (RANKL) and its receptor (RANK) are expressed in bone and skeletal muscle. Activation of the NF-κB pathway mainly inhibits myogenic differentiation, which leads to skeletal muscle dysfunction and loss. LYVE1 and CD206 positive macrophage has been reported to be associated with progressive impairment of skeletal muscle function with aging. The study aims to investigate the effects of an anti-RANKL treatment on sarcopenic skeletal muscle and explore the related mechanisms on muscle inflammation and the polarization status of macrophages.Sarcopenic senescence-accelerated mouse P8 (SAMP8) mice at month 8 were treated intraperitoneally with 5mg/kg anti-RANKL (IK22/5) or isotype control (2A3; Bio X Cell) antibody every 4 weeks and harvested at month 10. Senescence accelerated mouse resistant-1 (SAMR1) were collected at month 10 as the age-matched non-sarcopenic group. Ex-vivo functional assessment, grip strength and immunostaining of C/EBPa, CD206, F4/80, LYVE1 and PAX7 were performed. Data analysis was done with one-way ANOVA, and the significant level was set at p≤0.05.At month 10, tetanic force/specific tetanic force, twitch force/specific twitch force in anti-RANKL group were significantly higher than control group (all p<0.01). The mice in the anti-RANKL treatment group also showed significantly higher grip strength than Con group (p<0.001). The SAMP8 mice at month 10 expressed significantly more C/EBPa, CD206 and LYVE1 positive area than in SAMR1, while anti-RANKL treatment significantly decreased C/EBPa, CD206 and LYVE1 positive area.The anti-RANKL treatment protected against skeletal muscle dysfunctions through suppressing muscle inflammation and modulating M2 macrophages, which may represent a novel therapeutic approach for sarcopenia.Acknowledgment: Collaborative Research Fund (CRF, Ref: C4032-21GF)

Probing the relevance of the accelerated aging mouse line SAMP8 as a model for certain types of neuropsychiatric symptoms in dementia.

People with dementia (PwD) often present with neuropsychiatric symptoms (NPS). NPS are of substantial burden to the patients, and current treatment options are unsatisfactory. Investigators searching for novel medications need animal models that present disease-relevant phenotypes and can be used for drug screening. The Senescence Accelerated Mouse-Prone 8 (SAMP8) strain shows an accelerated aging phenotype associated with neurodegeneration and cognitive decline. Its behavioural phenotype in relation to NPS has not yet been thoroughly investigated. Physical and verbal aggression in reaction to the external environment (e.g., interaction with the caregiver) is one of the most prevalent and debilitating NPS occurring in PwD. Reactive aggression can be studied in male mice using the Resident-Intruder (R-I) test. SAMP8 mice are known to be more aggressive than the Senescence Accelerated Mouse-Resistant 1 (SAMR1) control strain at specific ages, but the development of the aggressive phenotype over time, is still unknown. In our study, we performed a longitudinal, within-subject, assessment of aggressive behaviour of male SAMP8 and SAMR1 mice at 4, 5, 6 and 7 months of age. Aggressive behaviour from video recordings of the R-I sessions was analysed using an in-house developed behaviour recognition software. SAMP8 mice were more aggressive relative to SAMR1 mice starting at 5 months of age, and the phenotype was still present at 7 months of age. Treatment with risperidone (an antipsychotic frequently used to treat agitation in clinical practice) reduced aggression in both strains. In a three-chamber social interaction test, SAMP8 mice also interacted more fervently with male mice than SAMR1, possibly because of their aggression-seeking phenotype. They did not show any social withdrawal. Our data support the notion that SAMP8 mice might be a useful preclinical tool to identify novel treatment options for CNS disorders associated with raised levels of reactive aggression such as dementia.

XANTHOHUMOL REDUCES THE EXPRESSION OF PRO-INFLAMMATORY AND OXIDATIVE STRESS MARKERS IN THE LUNG OF SENESCENCE-ACCELERATED PRONE MICE (SAMP8)

<h3>Objective</h3> Aging consists of a series of deleterious changes in cells and tissues along time, which lead to altered homeostasis. Nowadays we consider oxidative stress and inflammation the most relevant mechanisms of cell damage and dysfunction during aging. Both clinical and subclinical antigen exposure along life trigger a chronic inflammatory and oxidative response in the host. The lung, due to its position between the internal and the external milieu, is particularly exposed to pathogens and pollutants. An upregulation of oxidative stress and inflammation in lung tissue is expected. Xanthohumol, the major prenylated chalcone found in hops, has been shown to present anti-inflammatory and antioxidant properties in several organs, including liver, brain, and the reproductive system. Its effect on the aging lung has yet to be elucidated. For this reason, the aim of the present study was to evaluate the possible anti-inflammatory role of xanthohumol on a model of male senescence-accelerated prone mice (SAMP8). Design and method: Animals: young and old animals, aged 2 and 10 months respectively, were maintained under a 12:12 h light-dark cycle in an environmentally-controlled room and fed ad libitum. They were divided into 4 experimental groups: young non-treated, old non-treated, old treated with 1 mg/kg/day xanthohumol, and old treated with 5 mg/kg/day xanthohumol. Young and old non-treated male senescence-accelerated resistant mice (SAMR1) were used as controls. Treatment: xanthohumol was dissolved in ethanol and added to the drinking water. Only ethanol was administered to the water of non-treated animals. After 30 days of treatment, animals were sacrificed and lungs were collected and immediately frozen in liquid nitrogen. Inflammation and oxidative stress markers: both mRNA and protein levels of tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β), and heme oxygenase 1 (HO-1) were analyzed. mRNA nuclear factor NF-kappa-B (NFκB) levels were also quantified. mRNA and protein expressions were measured by RT-PCR and Western blotting, respectively. The results were analyzed by using ANOVA followed by Fisher's post-hoc test. <h3>Results</h3> Compared to the young animals, old non-treated SAMP8 mice presented significantly elevated (p<0.05) mRNA and protein levels of TNF-α, IL-1β, and HO-1. mRNA NFκB2 levels were also significantly increased (p<0.05). SAMR1 mice showed significantly decreased values (p<0.05). <h3>Conclusions</h3> Treatment with xanthohumol was able to decrease significantly (p<0.05) the age-induced elevation at any of the doses administered. Supplementing the diet with foodstuffs containing xanthohumol may be used as a potential tool for counteracting inflammation and oxidative stress in the aging lung.

Exogenous Nucleotides Improved the Oxidative Stress and Sirt-1 Protein Level of Brown Adipose Tissue on Senescence-Accelerated Mouse Prone-8 (SAMP8) Mice.

Brown adipose tissue (BAT) is of great importance in rodents for maintaining their core temperature via non-shivering thermogenesis in the mitochondria. BAT′s thermogenic function has been shown to decline with age. The activation of adenosine 5′-monophosphate (AMP)-activated protein kinase/sirtuin-1 (AMPK/Sirt-1) is effective in regulating mitochondrial function. Exogenous nucleotides (NTs) are regulatory factors in many biological processes. Nicotinamide mononucleotide (NMN), which is a derivative of NTs, is widely known as a Sirt-1 activator in liver and muscle, but the effect of NMN and NTs on aging BAT has not been studied before. The purpose of this study was to investigate the effect of NTs on aging senescence-accelerated mouse prone-8 (SAMP8) mice. Senescence-accelerated mouse resistant 1 (SAMR1) mice were set as the model control group and NMN was used as the positive control. Male, 3 month old SAMP8 mice were divided into the SAMP8-normal chow (SAMP8-NC), SAMP8-young-normal chow (SAMP8-young-NC), NMN, NTs-free, NTs-low, NTs-medium, and NTs-high groups for long-term feeding. After 9 months of intervention, interscapular BAT was collected for experiments. Compared to the SAMP8-NC, the body weight and BAT mass were significantly improved in the NT-treated aging SAMP8 mice. NT supplementation had effects on oxidative stress in BAT. The concentration of malondialdehyde (MDA) was reduced and that of superoxide dismutase (SOD) increased significantly. Meanwhile, the expression of the brown adipocyte markers uncoupling protein-1 (UCP-1), peroxisome proliferator-activated receptor-γ coactlvator-1α (PGC-1α), and PR domain zinc finger protein 16 (PRDM16) were upregulated. The upregulated proteins may be activated via the Sirt-1 pathway. Thus, NT supplementation may be helpful to improve the thermogenesis of BAT by reducing oxidative stress and activating the Sirt-1 pathway.

AAV-mediated expression of secreted and transmembrane αKlotho isoforms rescues relevant aging hallmarks in senescent SAMP8 mice.

Senescence represents a stage in life associated with elevated incidence of morbidity and increased risk of mortality due to the accumulation of molecular alterations and tissue dysfunction, promoting a decrease in the organism's protective systems. Thus, aging presents molecular and biological hallmarks, which include chronic inflammation, epigenetic alterations, neuronal dysfunction, and worsening of physical status. In this context, we explored the AAV9‐mediated expression of the two main isoforms of the aging‐protective factor Klotho (KL) as a strategy to prevent these general age‐related features using the senescence‐accelerated mouse prone 8 (SAMP8) model. Both secreted and transmembrane KL isoforms improved cognitive performance, physical state parameters, and different molecular variables associated with aging. Epigenetic landscape was recovered for the analyzed global markers DNA methylation (5‐mC), hydroxymethylation (5‐hmC), and restoration occurred in the acetylation levels of H3 and H4. Gene expression of pro‐ and anti‐inflammatory mediators in central nervous system such as TNF‐α and IL‐10, respectively, had improved levels, which were comparable to the senescence‐accelerated‐mouse resistant 1 (SAMR1) healthy control. Additionally, this improvement in neuroinflammation was supported by changes in the histological markers Iba1, GFAP, and SA β‐gal. Furthermore, bone tissue structural variables, especially altered during senescence, recovered in SAMP8 mice to SAMR1 control values after treatment with both KL isoforms. This work presents evidence of the beneficial pleiotropic role of Klotho as an anti‐aging therapy as well as new specific functions of the KL isoforms for the epigenetic regulation and aged bone structure alteration in an aging mouse model.

Effects of electroacupuncture on DNA methylation of the TREM2 gene in senescence-accelerated mouse prone 8 mice.

To explore the mechanism by which electroacupuncture (EA) upregulates triggering receptor expressed on myeloid cells 2 (TREM2) protein in the hippocampus of Alzheimer's disease (AD) model animals from the perspective of TREM2 DNA methylation. In total, 24 eight-month-old senescence-accelerated mouse prone 8 (SAMP8) mice were divided into an (untreated) AD group (n = 8), donepezil group (receiving donepezil treatment, n = 8) or EA group (receiving an EA intervention, n = 8). A healthy control group comprising 8-month-old senescence-accelerated mouse resistant 1 (SAMR1) mice (n = 8) was also included. Western blotting, bisulfite sequencing, and oxidative bisulfite sequencing were applied to test the relative expression of TREM2 protein and the methylation levels of the TREM2 gene. EA significantly upregulated the relative expression of TREM2 protein (p < 0.01), downregulated the 5-methylcytosine level (p < 0.01) and upregulated the 5-hydroxymethylcytosine level (p < 0.05) in the hippocampus. Downregulation of 5-methylcytosine levels and upregulation of 5-hydroxymethylcytosine levels in the TREM2 gene might be the mechanism by which EA promotes the expression of TREM2 protein.

A UPLC-Q-TOF/MS-Based Metabolomics Study on the Effect of Corallodiscus flabellatus (Craib) B. L. Burtt Extract on Alzheimer's Disease.

A UPLC-Q-TOF/MS-based metabolomics study was carried out to explore the intervening mechanism of Corallodiscus flabellatus (Craib) B. L. Burtt (CF) extract on Alzheimer's disease (AD). The AD model group consisted of senescence-accelerated mouse prone 8 (SAMP8) mice, and the control group consisted of senescence-accelerated mouse resistant 1 (SAMR1) mice. UPLC-Q-TOF/MS detection, multivariate statistical analysis, and pathway enrichment were jointly performed to research the change in metabolite profiling in the urine of AD mice. The result suggested that the metabolite profiling of SAMP8 mice significantly changed at the sixth month compared with SAMR1 mice of the same age, and the principal component analysis (PCA) score scatter plots of the CF group closely resembled those of the control and positive drug (huperzine A, HA) group. A total of 28 metabolites were considered potential biomarkers associated with the metabolism of beta-alanine, glycine, serine, threonine, cysteine, methionine, arginine, proline, and purines in AD mice. Furthermore, the CF group was clustered with the control and positive group and was clearly separated from the model group in the heat map. In conclusion, significant anti-AD effects were firstly observed in mice after treatment with the CF extract, and the urinary metabolomics approach assisted with dissecting the underlying mechanism.

Anti-aging effects of a functional food via the action of gut microbiota and metabolites in aging mice.

Wushen (WS) is a mixed food containing 55 natural products that is beneficial to human health. This study aimed to reveal the preventive effect of WS on aging via a combined analysis of gut microbiome and metabolome. Senescence-accelerated mouse prone 8 (SAMP8) mice were used as aging model and senescence-accelerated mouse resistant 1 (SAMR1) mice as control. The mice were fed four diet types; control diet (for SAMR1 mice), standard diet (for SAMP8 mice, as SD group), WS diet, and fecal microbiota transplantation (FMT; transplanted from aging-WS mice). Our results showed that the weight, food intake, neurological function, and general physical conditions significantly improved in WS-fed mice compared to those fed with SD. The CA1 hippocampal region in WS-fed aged mice showed fewer shriveled neurons and increased neuronal layers compared to that of the SD group. WS-fed mice showed a decrease in malondialdehyde and an increase in superoxide dismutase levels in the brain; additionally, IL-6 and TNF-α levels significantly decreased, whereas IL-2 levels and the proportion of lymphocytes, CD3+CD8+ T, and CD4+IFNγ+T cells increased in WS-fed mice. After fed with WS, the abundance of Ruminococcus and Butyrivibrio markedly increased, whereas Lachnoclostridium and Ruminiclostridium significantly decreased in the aging mice. In addition, 887 differentially expressed metabolites were identified in fecal samples, among these, Butyrivibrio was positively correlated with D-glucuronic acid and Ruminococcus was positively associated with 5-acetamidovalerate. These findings provide mechanistic insight into the impact of WS on aging, and WS may be a valuable diet for preventing aging.

Evaluation of SAMP8 Mice as a Model for Sleep-Wake and Rhythm Disturbances Associated with Alzheimer's Disease: Impact of Treatment with the Dual Orexin (Hypocretin) Receptor Antagonist Lemborexant.

Background:Many patients with Alzheimer’s disease (AD) display circadian rhythm and sleep-wake disturbances. However, few mouse AD models exhibit these disturbances. Lemborexant, a dual orexin receptor antagonist, is under development for treating circadian rhythm disorders in dementia.Objective:Evaluation of senescence-accelerated mouse prone-8 (SAMP8) mice as a model for sleep-wake and rhythm disturbances in AD and the effect of lemborexant by assessing sleep-wake/diurnal rhythm behavior.Methods:SAMP8 and control senescence-accelerated mouse resistant-1 (SAMR1) mice received vehicle or lemborexant at light onset; plasma lemborexant and diurnal cerebrospinal fluid (CSF) orexin concentrations were assessed. Sleep-wake behavior and running wheel activity were evaluated.Results:Plasma lemborexant concentrations were similar between strains. The peak/nadir timing of CSF orexin concentrations were approximately opposite between strains. During lights-on, SAMP8 mice showed less non-rapid eye movement (non-REM) and REM sleep than SAMR1 mice. Lemborexant treatment normalized wakefulness/non-REM sleep in SAMP8 mice. During lights-off, lemborexant-treated SAMR1 mice showed increased non-REM sleep; lemborexant-treated SAMP8 mice displayed increased wakefulness. SAMP8 mice showed differences in electroencephalogram architecture versus SAMR1 mice. SAMP8 mice exhibited more running wheel activity during lights-on. Lemborexant treatment reduced activity during lights-on and increased activity in the latter half of lights-off, demonstrating a corrective effect on overall diurnal rhythm. Lemborexant delayed the acrophase of activity in both strains by approximately 1 hour.Conclusion:SAMP8 mice display several aspects of sleep-wake and rhythm disturbances in AD, notably mistimed activity. These findings provide some preclinical rationale for evaluating lemborexant in patients with AD who experience sleep-wake and rhythm disturbances.

Interleukin-1β Modulates Synaptic Transmission and Synaptic Plasticity During the Acute Phase of Sepsis in the Senescence-Accelerated Mouse Hippocampus.

BackgroundAging and pre-existing cognitive impairment are considered to be independent risk factors for sepsis-associated encephalopathy. This study aimed to investigate the manner in which aging and pre-existing cognitive dysfunction modified neuroinflammation, synaptic plasticity, and basal synaptic transmission during the acute phase of sepsis using Senescence-Accelerated Mice Prone 8 (SAMP8) and Senescence-Accelerated Resistant Mice 1 (SAMR1).MethodsWe used 6-month-old SAMP8 and SAMR1. Sepsis was induced using cecal ligation and puncture (CLP). The animal’s hippocampi and blood were collected for subsequent investigations 24 h after surgery.ResultsLong-term potentiation (LTP) was impaired in the Shaffer-collateral (SC)-CA1 pathway of the hippocampus in SAMP8 without surgery compared to the age-matched SAMR1, which was reflective of cognitive dysfunction in SAMP8. CLP impaired the SC-CA1 LTP in SAMR1 compared to the sham-operated controls, but not in SAMP8. Moreover, CLP decreased the input-output curve and increased the paired-pulse ratio in SAMP8, suggesting the reduced probability of basal synaptic transmission due to sepsis. Immunohistochemical analysis revealed that CLP elevated IL-1β levels, especially in the hippocampi of SAMP8 with microglial activation. In vivo peripheral IL-1 receptor antagonist (IL-1ra) administration in the septic SAMP8 revealed that the neuroinflammation was not correlated with the peripheral elevation of IL-1β. Ex vivo IL-1ra administration to the hippocampus ameliorated LTP impairment in SAMR1 and the reduction in basal transmission in SAMP8 after sepsis.ConclusionsThe mechanism of the modulation of synaptic transmission and synaptic plasticity by the acute stage of sepsis differed between SAMR1 and SAMP8. These changes were related to centrally derived IL-1 receptor-mediated signaling and were accompanied by microglial activation, especially in SAMP8.

Neuroinflammaging underlies emotional disturbances and circadian rhythm disruption in young male senescence-accelerated mouse prone 8 mice.

Aging causes psychological dysfunction and neurodegeneration, and can lead to cognitive impairments. Although numerous studies have reported that neurodegeneration and subsequent cognitive impairments are involved in neuroinflammation, relationship between psychological disturbance and neuroinflammation with aging (neuroinflammaging) remains unclear. Here, to clarify the relationship, we examined whether neuroinflammaging affects emotional behaviors in senescence-accelerated mouse prone 8 (SAMP8) mice. Microglial inflammatory responses to a subsequent lipopolysaccharide (LPS) challenge were significantly enhanced in male SAMP8 mice relative to normal aging senescence-accelerated mouse resistant 1 (SAMR1) mice at 17 weeks, but not 8 weeks of age. LPS injection also significantly increased brain and systemic inflammation in SAMP8 mice at 17 weeks. In a battery of behavioral tests, SAMP8 mice at 17 weeks, but not 8 weeks, exhibited anxiety- and depression-like behaviors and circadian rhythm disruption. Taken together, SAMP8 mice at 17 weeks possess a brain microenvironment in which it is easier to trigger neuroinflammatory priming; this may lead to an emergence of anxiety- and depression-like behaviors and circadian rhythm disruption. These findings provide new insights into the temporal relationship between neuroinflammaging and emotion.

Bone progeria diminished the therapeutic effects of bone marrow mesenchymal stem cells on retinal degeneration

Senescence is closely related to the occurrence of retinal degeneration. Recent studies have shown that bone marrow mesenchymal stem cells (BMMSCs) have significant therapeutic effects on retinal degeneration, While BMMSCs suffer from functional decline in bone aging. Whether senescence affects BMMSCs therapy on retinal degeneration remains unknown. Here, we applied the previously established bone progeria animal model, the senescence-accelerated mice-prone 6 (SAMP6) strain, and surprisingly discovered that SAMP6 mice demonstrated retinal degeneration at 6 months old. Furthermore, BMMSCs derived from SAMP6 mice failed to prevent MNU-induced retinal degeneration in vivo. As expected, BMMSCs from SAMP6 mice exhibited impairment in the differentiation capacities, compared to those from the age-matched senescence-accelerated mice-resistant 1 (SAMR1) strain. Moreover, BMMSCs from SAMR1 mice counteracted MNU-induced retinal degeneration, with increased expression of the retina survival hallmark, N-myc downstream regulated gene 2 (NDRG2). Taken together, these findings reveal that bone progeria diminished the therapeutic effects of BMMSC on retinal degeneration.

β-Cryptoxanthin Improves p62 Accumulation and Muscle Atrophy in the Soleus Muscle of Senescence-Accelerated Mouse-Prone 1 Mice.

We investigated the effects of β-cryptoxanthin on skeletal muscle atrophy in senescence-accelerated mouse-prone 1 (SAMP1) mice. For 15 weeks, SAMP1 mice were intragastrically administered vehicle or β-cryptoxanthin. At 35 weeks of age, the skeletal muscle mass in SAMP1 mice was reduced compared with that in control senescence-accelerated mouse-resistant 1 (SAMR1) mice. β-cryptoxanthin increased muscle mass with an increase in the size of muscle fibers in the soleus muscle of SAMP1 mice. The expressions of autophagy-related factors such as beclin-1, p62, LC3-I, and LC3-II were increased in the soleus muscle of SAMP1 mice; however, β-cryptoxanthin administration inhibited this increase. Unlike in SAMR1 mice, p62 was punctately distributed throughout the cytosol in the soleus muscle fibers of SAMP1 mice; however, β-cryptoxanthin inhibited this punctate distribution. The cross-sectional area of p62-positive fiber was smaller than that of p62-negative fiber, and the ratio of p62-positive fibers to p62-negative fibers was increased in SAMP1 mice. β-cryptoxanthin decreased this ratio in SAMP1 mice. Furthermore, β-cryptoxanthin decreased the autophagy-related factor expression in murine C2C12 myotube. The autophagy inhibitor bafilomycin A1, but not the proteasome inhibitor MG132, inhibited the β-cryptoxanthin-induced decrease in p62 and LC3-II expressions. These results indicate that β-cryptoxanthin inhibits the p62 accumulation in fibers and improves muscle atrophy in the soleus muscle of SAMP1 mice.

MiR-340 Reduces the Accumulation of Amyloid-β Through Targeting BACE1 (β-site Amyloid Precursor Protein Cleaving Enzyme 1) in Alzheimer's Disease.

Alzheimer's disease (AD) is the most common neurodegenerative disease, and the accumulation of amyloid-β is the initial process in AD. MicroRNAs (miRNAs) are widely known as key regulators of the accumulation of amyloid-β in AD. This study analyzed the potential effects and possible internal mechanisms of miR-340 on AD. The expression of miR-340 in senescence-accelerated mouse prone-8 (SAMP8) mouse and senescence-accelerated mice/resistant-1 (SAMR1) mouse was evaluated by qRT-PCR (quantitative real-time polymerase chain reaction). The expression of β-site amyloid precursor protein cleaving enzyme 1 (BACE1) was determined by qRT-PCR and western blot. The binding ability between miR-340 and BACE1 was verified by dual-luciferase reporter assay. In vitro cell model of AD was established in human neuroblastoma SH-SY5Y cells transfected with Swedish mutant form of amyloid precursor protein (APPswe). The effect of miR-340 on the accumulation of amyloid- β was investigated by western blot analysis. Flow cytometry was conducted to detect cell apoptosis. MiR-340 was down-regulated in the hippocampus of AD model SAMP8 mouse compared to SAMR1 mouse, while BACE1 was up-regulated in SAMP8, suggesting a negative correlation between miR-340 and BACE1 in SAMP8 mouse. MiR-340 could directly bind with BACE1, and over-expression of miR-340 decreased expression of BACE1 in SH-SY5Y/APPswe cells. MiR- 340 reduced the accumulation of amyloid-β and suppressed cell apoptosis through targeting BACE1 in SH-SY5Y/APPswe cells. MiR-340 was downregulated in AD and reduced the accumulation of amyloid-β through targeting BACE1, suggesting a potential therapeutic target for AD.