Senescent Rats Research Articles

An endophenotype network strategy uncovers YangXue QingNao Wan suppresses Aβ deposition, improves mitochondrial dysfunction and glucose metabolism

BackgroundAlzheimer's disease (AD), an escalating global health issue, lacks effective treatments due to its complex pathogenesis. YangXue QingNao Wan (YXQNW) is a China Food and Drug Administration (CFDA)- approved TCM formula that has been repurposed in clinical Phase II for the treatment of AD. Identifying YXQNW's active ingredients and their mechanisms is crucial for developing effective AD treatments. PurposeThis study aims to elucidate the anti-AD effects of YXQNW and to explore its potential therapeutic mechanisms employing an endophenotype network strategy. MethodsHerein we present an endophenotype network strategy that combines active ingredient identification in rat serum, network proximity prediction, metabolomics, and in vivo experimental validation in two animal models. Specially, utilizing UPLC-Q-TOF-MS/MS, active ingredients are identified in YXQNW to build a drug-target network. We applied network proximity to identify potential AD pathological mechanisms of YXQNW via integration of drug-target network, AD endophenotype gene sets, and human protein interactome, and validated related mechanisms in two animal models. In a d-galactose-induced senescent rat model, YXQNW was administered at varying doses for cognitive and neuronal assessments through behavioral tests, Nissl staining, and transmission electron microscopy (TEM). Metabolomic analysis with LC-MS revealed YXQNW's influence on brain metabolites, suggesting therapeutic pathways. Levels of key proteins and biochemicals were measured by WB and ELISA, providing insights into YXQNW's neuroprotective mechanisms. In addition, 5×FAD model mice were used and administered YXQNW by gavage for 14 days at two doses. Amyloid-β levels, transporter expression, and cerebral blood flow have been detected by MRI and biochemical assays. ResultsThe network proximity analysis showed that the effect of YXQNW on AD was highly correlated with amyloid β, synaptic function, glucose metabolism and mitochondrial function. The results of metabolomics combined with in vivo experimental validation suggest that YXQNW has the potential to ameliorate glucose transport abnormalities in the brain by upregulating the expression of GLUT1 and GLUT3, while further enhancing glucose metabolism through increased O-GlcNAcylation and mitigating mitochondrial dysfunction via the AMPK/Sirt1 pathway, thereby improving d-galactose-induced cognitive deficits in rats. Additionally, YXQNW treatment significantly decreased Aβ1–42 levels and enhanced cerebral blood flow (CBF) in the hippocampus of 5×FAD mice. while mechanistic findings indicated that YXQNW treatment increased the expression of ABCB1, an Aβ transporter, in 5×FAD model mice to promote the clearance of Aβ from the brain and alleviate AD-like symptoms. ConclusionsThis study reveals that YXQNW may mitigate AD by inhibiting Aβ deposition and ameliorating mitochondrial dysfunction and glucose metabolism, thus offering a promising therapeutic approach for AD.

Alterations of Liver Morphology in Senescent Rats.

Age-related liver changes can have important implications for health and metabolic function. This study aimed to describe the morphoquantitative alterations of the liver in senescent rats compared to adult rats. Twelve male rats were used, divided into 6-month-old adults (group A) and 36-month-old senescent rats (group S). Morphometric and histopathological studies, quantification of collagen types I and III, and stereological analyses were performed to determine the volume density of mononucleated (VvhepM) and binucleated (VvhepB) hepatocyte nuclei, surface area density (SvhepM), and number density (NvhepM) of mononucleated hepatocyte nuclei. The findings reveal an alteration of the normal liver tissue architecture in senescent rats and the presence of inflammatory lesions and fibrosis. In addition, there was a decrease in body and liver mass and volume. Group S showed a significant reduction in VvhepM and NvhepM; however, SvhepM was significantly higher. No significant differences were noted in the percentage of binucleated hepatocytes between the two groups. This study reveals substantial morphological changes in the aging liver, with possible functional implications. More research is needed on the underlying mechanisms and their consequences at older ages.

Deacetylation of HnRNP U mediated by sirtuin1 ameliorates aged rat with liver fibrosis via inhibiting p53-related senescence and NLRP3-related inflammation

Senescence represents a major risk factor promoting liver fibrosis progression. Sirtuin 1 (SIRT1), an essential regulator of cellular senescence, may be involved in developing liver fibrosis. However, the role and mechanism of SIRT1 in liver fibrosis development were largely unknown. We constructed the liver fibrosis in aged rats induced by carbon tetrachloride (CCl4) and then transfected with GFP-SIRT1 adenoviral vectors. After that, we performed acetylomic analysis of liver tissue in aged rats to identify potential substrates of SIRT1. Furthermore, replicative senescent rat hepatocytes were pretreated with siRNA HnRNP U, SIRT1 adenoviral vectors, resveratrol, and siRNA SIRT1, following stimulation with H2O2. We found that the protein levels of SIRT1 and HnRNP U were down-regulation in aged rat liver fibrotic tissues, with an accumulation of NLRP3 inflammasome and activation of the p53/p21 pathway in liver tissue, as well as an increased level of plasma IL-1β secretion. In comparison, these effects were reversed by overexpressing SIRT1 with adenoviral vectors. Acetylation of HnRNP U and its sites at K28 and K787 might be potential targets for SIRT1-mediated liver fibrosis in aged rats. Silencing HnRNP U reduced H2O2-induced up-regulation expression of p53, p21, and NLRP3 inflammasome at protein levels. Additionally, H2O2 induced high acetylation of HnRNP U in senescent hepatocytes, whereas overexpressing SIRT1 with adenoviral vectors and resveratrol deacetylate HnRNP U to inhibit NLRP3 inflammasome and the p53/p21 pathway. Besides, the silence of SIRT1 aggravated H2O2-induced p53-related senescence and NLRP3-related inflammation in senescent hepatocytes. Our findings suggested that deacetylation of HnRNPU mediated by SIRT1 attenuated liver fibrosis in the elderly by inhibiting p53/p21 pathway and NLRP3-related inflammation.

Epicatechin‐mediated modulation of the Nrf2/HO‐1 pathway alleviates senile cerebral ischemic/reperfusion injury

AbstractExcessive reactive oxygen species (ROS) generated during cerebral ischemic reperfusion (CIRI) are crucial for subsequent tissue damage. However, despite the potential benefits of antioxidants reported in clinical applications, few have proven effective in treating CIRI, particularly in the elderly. Epicatechin (EC) is a catechol flavonoid monomer derived from natural tea plants. Multiple phenolic hydroxyl groups give it strong antioxidant properties, which can not only degrade ROS through chemical reactions between hydroxyl and ROS but also enhance the activity of antioxidant enzymes in cells, and it is easy to penetrate the blood–brain barrier. But its antagonistic effect on age‐related CIRI and potential medicinal value are still unknown. Nuclear factor erythroid 2‐related factor 2 (Nrf2) is the most important transcription factor regulating the expression of antioxidant proteins in the body. This study first compared the pathological differences of the Nrf2 system in CIRI between 2‐month‐old and 12‐month‐old Sprague–Dawley (SD) rats. Subsequently, EC was administered to 12‐month‐old rat models of middle cerebral artery occlusion and reperfusion (MCAO/R) and senescent SH‐SY5Y cell models subjected to oxygen glucose deprivation/reoxygenation (OGD/R). EC treatment improved cerebral morphology and function; increased p‐Nrf2, heme oxygenase‐1 (HO‐1), superoxide dismutase (SOD), and glutathione (GSH) expression; reduced infarct volume; and neuronal apoptosis in senescent rats. Moreover, EC enhanced cellular activity and the expression of p‐Nrf2, HO‐1, and quinone oxidoreductase‐1 (NQO‐1) while decreasing ROS and malondialdehyde (MDA) levels and mitigating apoptosis in senescent SH‐SY5Y cells. These effects were reversed upon si‐Nrf2. In sum, we confirm that EC exerts neuroprotective effects by upregulating Nrf2/ARE and reducing oxidative stress, suggesting that EC may be a promising drug for the treatment of senile cerebral apoplexy. This study also provides a scientific basis for the development and selection of new drugs for ischemic stroke in elderly patients.

Coenzyme Q10 and exercise training reinstate middle cerebral artery occlusion-induced behavioral deficits and hippocampal long-term potentiation suppression in aging rats.

Patients experience post-stroke cognitive impairment during aging. To date, no specific treatment solution has been reported for this disorder. The purpose of this study was to evaluate the effects of exercise training and coenzyme Q10 supplementation on middle cerebral artery occlusion (MCAO) induced behavioral impairment, long-term potentiation inhibition and cerebral infarction size in aging rats. Fifty aging male rats underwent MCAO surgery and were randomly distributed in to the following groups: 1-Sham, 2- control, 3- Coenzyme Q10, 4- Exercise training and 5- Exercise training with Q10 supplementation (Ex + Q10). Aerobic training groups were allowed to run on a treadmill for 12 weeks. Q10 (50mg/kg) was administered intragastrically by gavage. Morris water maze, shuttle box and elevated plus maze tests were used to evaluate cognitive function. The population spike (PS) amplitude and slope of excitatory postsynaptic potentials (EPSP) in the dentate gyrus area were recorded as a result of perforant pathway electrical stimulation. Our study showed that Q10 and aerobic training alone ameliorate spatial memory in the acquisition phase, but have no effect on spatial memory in the retention phase. Q10 and exercise training synergistically promoted spatial memory in the retention phase. Q10 and exercise training separately and simultaneously mitigated cerebral ischemia-induced passive avoidance memory impairment in acquisition and retention phases. The EPSP did not differ between the groups, but exercise training and Q10 ameliorate the PS amplitude in hippocampal responses to perforant path stimulation. Exercising and Q10 simultaneously reduced the cerebral infarction volume. Collectively, the findings of the present study imply that 12 weeks of aerobic training and Q10 supplementation alone can simultaneously reverse cerebral ischemia induced neurobehavioral deficits via amelioration of synaptic plasticity and a reduction in cerebral infarction volume in senescent rats.

The effect of brain serotonin deficit (TPH2-KO) on the expression and activity of liver cytochrome P450 enzymes in aging male Dark Agouti rats

BackgroundLiver cytochrome P450 (CYP) greatly contributes to the metabolism of endogenous substances and drugs. Recent studies have demonstrated that CYP expression in the liver is controlled by the central nervous system via hormonal pathways. In particular, the expression of hepatic CYPs is negatively regulated by the brain serotoninergic system. The present study aimed to investigate changes in the function of the main liver drug-metabolizing CYP enzymes as a result of serotonin depletion in the brain of aging rats, caused by knockout of brain tryptophan hydroxylase gene (TPH2-KO).MethodsThe hepatic CYP mRNA (qRT-PCR), protein level (Western blotting) and activity (HPLC), and serum hormone levels (ELISA) were measured in Dark Agouti wild-type (WT) male rats (mature 3.5-month-old and senescent 21-month-old) and in TPH2-KO senescent animals.ResultsThe expression/activity of the studied CYPs decreased with age in the liver of wild-type rats. The deprivation of serotonin in the brain of aging males decreased the mRNA level of most of the studied CYPs (CYP1A/2A/2B/3A), and lowered the protein level of CYP2C11 and CYP3A. In contrast, the activities of CYP2C11, CYP3A and CYP2C6 were increased. The expression of cytochrome b5 decreased in aging rats, but increased in TPH2-deficient senescent animals. The serum concentration of growth hormone declined in the aged and further dropped down in TPH2-deficient senescent rats.ConclusionsRat liver cytochrome P450 functions deteriorate with age, which may impair drug metabolism. The TPH2 knockout, which deprives brain serotonin, affects cytochrome P450 expression and activity differently in mature and senescent male rats.

The microarchitecture and chemical composition of the femur neck of senescent female rats after different physical training protocols.

A sedentary lifestyle, coupled with a decrease in estrogen, impairs bone homeostasis, favoring to the development of osteopenia and osteoporosis, both recognized as risk factors for fractures. Here, we investigated the quality of the femur, particularly the femur neck region, and the ambulation performance of senescent rats subjected to three different physical training protocols during the periestropause period. Forty-eight female rats, 18 months of age, were subjected to a 120-day training period, three times a week. The rats were distributed into four groups: aerobic training (AT), strength training (ST), concurrent training (CT), or no training (NT). After the experimental period, at 21 months of age, ambulation performance and femur were analyzed using microtomography, Raman stereology, densitometry, and mechanical strength tests. The results demonstrated greater remodeling activity and improvement in resistance and bone microarchitecture in the femur neck of senescent female rats after undergoing physical training. Our verified higher intensities of bands related to collagen, phosphate, amide III, and amide I. Furthermore, the analysis of the secondary collagen structures indicated alterations in the collagen network due to the exercise, resulting in increased bone strength. Both AT and strength-based training proved beneficial, with AT showing greater adaptations in bone density and stiffness in the femur, while strength-based training greater adaptations in trabecular and cortical structure. These insights contribute to the understanding of the potential interventions for preventing osteopenia and osteoporosis, which are critical risk factors for fractures.

Calafiore cardioplegia offers better myocardial protection in adult and senescent rat hearts than Del Nido cardioplegia.

We compared the cardioprotective capacity of Del Nido cardioplegia and warm Calafiore blood cardioplegia in an experimental setting during 90min of ischaemia. 20 adult and 20 senescent rat hearts were isolated and mounted on a blood-perfused, pressure-controlled Langendorff apparatus. After a stabilization period, cardiac arrest (90min) was induced by the administration of either Calafiore (Cala) or Del Nido solution (DNS). While Cala was given warm and intermittently, DNS was given as a cold single shot. During 90min of reperfusion, cardiac function and metabolism were evaluated and biomarker levels were measured. After the end of the experiment, hearts were prepared for electronmicroscopic investigation. Hearts exposed to Cala recovered faster during reperfusion compared with hearts administered DNS (Cala vs DNS at 30min reperfusion: left ventricular developed pressure 72, SD: 22% of baseline (BL) versus 40, SD: 32% of BL, p < .001, and positive derived left ventricular pressure over time was better in both adult and senescent Cala groups (96, SD: 31% of BL) than in the DNS groups (39, SD: 27% of BL, p < .001). Ischaemic contractures were seen in the DNS groups starting after 30min of ischaemia, whereas no rise in diastolic pressure was observed for the Cala groups. Accordingly, lactate production was higher after DNS (1.23mg/dl (SD 0.87) than after Cala (0.33mg/dl (SD 0.68), p = .015) at the beginning of reperfusion. Troponin I levels at the end of reperfusion were higher after DNS treatment in adult hearts (DNS: 287.9 SD: 147.7ng/mL vs Cala 91.2: SD: 94.7ng/mL, p = .02) and in senescent hearts (DNS: 376.5 (SD: 162.8) ng/ml versus Cala 104.7 (SD: 150.2) ng/ml, p = .025). Electron microscopy showed that the cellular oedema index was higher in adult DNS hearts (1.2 ± 0.2) than in adult Cala hearts (0.8 ± 0.1, p = .012), whereas the VS ratio was similar (0.18 ± 0.01 vs 0.17 ± 0.03). Calafiore cardioplegia offers better myocardial protection from ischaemia/reperfusion-related damage in isolated perfused adult and senescent rat hearts than Del Nido cardioplegia.

Propolis as a Potential Therapeutic Agent to Counteract Age-Related Changes in Cartilage: An In Vivo Study.

Aging is intricately linked to chronic low-grade systemic inflammation, which plays a significant role in various age-related conditions, including osteoarthritis (OA). The aging process significantly influences the development of OA due to alterations in cartilage composition, reduced proteoglycan content, dysregulation of growth factor signaling, and heightened oxidative stress. Propolis, a natural product renowned for its potent antioxidant and anti-inflammatory properties, has the potential to mitigate age-induced changes in cartilage. The primary objective of this study was to rigorously assess the impact of in vivo propolis treatment on the histopathological characteristics of knee articular cartilage in senescent rats. This study involved a cohort of twenty male Sprague-Dawley rats, randomly allocated into four distinct groups for comparative analysis: YR (control group consisting of young rats), SR (senescent rats), SR-EEP (senescent rats treated with an ethanolic extract of propolis, EEP), and SR-V (senescent rats administered with a control vehicle). This study employed comprehensive histological and stereological analyses of knee articular cartilage. Propolis treatment exhibited a significant capacity to alleviate the severity of osteoarthritis, enhance the structural integrity of cartilage, and augment chondrocyte density. These promising findings underscore the potential of propolis as a compelling therapeutic agent to counteract age-related alterations in cartilage and, importantly, to potentially forestall the onset of osteoarthritis.

The preconditioning effect of different exercise training modes on middle cerebral artery occlusion induced-behavioral deficit in senescent rats

IntroductionBrain abilities decrease after brain stroke in elderly. The neuroprotective effect of exercise training has been proved in clinical trials and animal experiment. Nevertheless, it is not still clear what kind of exercise has greater protective effect. The present study aimed at investigating pre-conditioning effect of endurance, resistance, and concurrent training on learning ability, anxiety, and spatial memory in aged rats following stroke strength with middle cerebral artery occlusion. MethodWe used 50 male Wistar rats (age = 24 months) that were assigned randomly in five groups; 1: sham group, 2: Control group 3: Endurance training 4: Resistance training, and 5: concurrent training. The exercise training groups received training for four weeks. Following training, middle cerebral artery occlusion was applied to induce cerebral ischemia. Using the elevated plus maze, shuttle box test, and Morris water maze, neurocognitive functions were tested in the sample rats. ResultsIt was found that resistance training did not affect spatial memory in the acquisition phase, while concurrent training and endurance training enhanced spatial memory in the acquisition phase. On the contrary, spatial memory was improved by resistance training in the retention phase, while concurrent and endurance exercises did not affect spatial memory in the retention phase. Passive avoidance learning ability at acquisition phase was more in resistance group compared to the endurance and concurrent training in shuttle box test, but in retention phase was similar between training groups. Unlike endurance and concurrent training, resistance training reduced anxiety in senescent rats. ConclusionAll three exercise types alleviated aversive learning and memory impairment induced by stroke in senescent rats. Notably, the resistance training showed a greater protective effect compared to the other two training methods.

Curcumin displays a potent caloric restriction mimetic effect in an accelerated senescent model of rat.

Curcumin, a strong natural compound with numerous health benefits, is extracted from the Curcuma longa. According to recent research findings, it also acts as a calorie restriction mimetic. We examined established aging biomarkers in erythrocytes and plasma and tested a persistent oral dietary dose of curcumin in young and D-galactose-induced accelerated rat aging models. For four weeks, D-gal (300mg/kg b.w. subcutaneously) and curcumin (200mg/kg b.w. oral) were administered simultaneously to test the protective effects of curcumin against D-galactose-induced accelerated aging and oxidative stress. In the accelerated senescent rat model, we discovered a significant rise in protein carbonyl, malonaldehyde (MDA), and advanced oxidation protein products. Increased levels of catalase, superoxide dismutase, ferric-reducing antioxidant potential, and reduced glutathione (GSH) were observed. Our findings reveal that curcumin has characteristics resembling a calorie restriction mimic and can successfully maintain redox equilibrium throughout the aging process in rat erythrocytes and plasma.

Age-related modifications in CYP-dependent drug metabolism: role of stress.

Accumulating clinical evidence indicates extensive inter-individual variations in the effectiveness and adverse effects of standard treatment protocols, which are largely attributed to the multifactorial regulation of the hepatic CYP-dependent drug metabolism that is connected with either transcriptional or post-translational modifications. Age and stress belong to the most important factors in CYP gene regulation. Alterations in neuroendocrine responses to stress, which are associated with modified hypothalamo-pituitary-adrenal axis function, usually accompany ageing. In this light, ageing followed by a decline of the functional integrity of organs, including liver, a failure in preserving homeostasis under stress, increased morbidity and susceptibility to stress, among others, holds a determinant role in the CYP-catalyzed drug metabolism and thus, in the outcome and toxicity of pharmacotherapy. Modifications in the drug metabolizing capacity of the liver with age have been reported and in particular, a decline in the activity of the main CYP isoforms in male senescent rats, indicating decreased metabolism and higher levels of the drug-substrates in their blood. These factors along with the restricted experience in the use of the most medicines in childhood and elderly, could explain at an extent the inter-individual variability in drug efficacy and toxicity outcomes, and underscore the necessity of designing the treatment protocols, accordingly.

Cardioprotective effects of exercise preconditioning on ischemia-reperfusion injury and ventricular ectopy in young and senescent rats.

Aging decreases ischemic tolerance, while exercise prevents myocardial ischemia reperfusion (IR) injury. The cardioprotective role of high intensity interval training (HIIT), however, is unknown. Accordingly, we investigated 8weeks (5days/week, 40min/day) of HIIT treadmill exercise (60%/90% of VO2 peak) on IR injury in young (2-month) and senescent (20-month) Wistar rat myocardia (N=10/group). Surgical IR (30min/120min) was performed via reversible left anterior descending artery ligation and ECG was analyzed to determine ventricular ectopy during IR period. Infarction size and oxidative stress were measured in hearts post-mortem. Glutathione peroxidase activity and Myeloperoxidase levels were mitigated with age, but elevated post IR. HIIT potentiated antioxidant defenses in young and old hearts, and infarction size was lower in young HIIT trained. Metrics of reactive oxygen species were not lower after IR, and were not affected by HIIT in young or old rats. Ventricular ectopy score in senescent rats was insignificantly more than young rats and HIIT significantly decreased ventricular ectopy score in young and senescent rats. Findings indicate that IR tolerance is mitigated in senescent hearts, while HIIT ameliorated infarction by increasing antioxidant enzymes activity in young and senescent hearts.

Pcsk6 Deficiency Promotes Cardiomyocyte Senescence by Modulating Ddit3-Mediated ER Stress.

Cardiac aging is a critical determinant of cardiac dysfunction, which contributes to cardiovascular disease in the elderly. Proprotein convertase subtilisin/kexin 6 (PCSK6) is a proteolytic enzyme important for the maintenance of cardiac function and vascular homeostasis. To date, the involvement of PCSK6 in cardiac aging remains unknown. Here we report that PCSK6 expression decreased in the hearts of aged mice, where high levels cyclin dependent kinase inhibitor 2A (P16) and cyclin dependent kinase inhibitor 1A (P21) (senescence markers) were observed. Moreover, PCSK6 protein expression was significantly reduced in senescent rat embryonic cardiomyocytes (H9c2) induced by D-galactose. Pcsk6 knockdown in H9c2 cells increased P16 and P21 expression levels and senescence-associated beta-galactosidase activity. Pcsk6 knockdown also impaired cardiomyocyte function, as indicated by increased advanced glycation end products, reactive oxygen species level, and apoptosis. Overexpression of PCSK6 blunted the senescence phenotype and cellular dysfunction. Furthermore, RNA sequencing analysis in Pcsk6-knockdown H9c2 cells identified the up-regulated DNA-damage inducible transcript 3 (Ddit3) gene involved in endoplasmic reticulum (ER) protein processing. Additionally, DDIT3 protein levels were remarkably increased in aged mouse hearts. In the presence of tunicamycin, an ER stress inducer, DDIT3 expression increased in Pcsk6-deficient H9c2 cells but reduced in PCSK6-overexpressing cells. In conclusion, our findings indicate that PCSK6 modulates cardiomyocyte senescence possibly via DDIT3-mediated ER stress.

Intrinsic innervation of the ovary and its variations in the rat senescence process

Ovarian functions decrease with perimenopause. The ovary has extrinsic innervation, but the neural influence on ovarian functions and dysfunction is not well-studied. The present study aimed to biochemically and morphometrically characterize the intrinsic neurons in ovaries from young adult, middle-aged, and senescent Long Evans CII-ZV rats (3, 12, and 15 months old, respectively). Ovaries were extracted from four rats of each age group (n = 12 total), cryopreserved, and processed for immunofluorescence studies with the primary NeuN/β-tubulin and NeuN/tyrosine hydroxylase (TH) antibodies. The soma area and number of intrinsic neurons in the ovarian stroma, surrounding follicles, corpus luteum, or cyst were evaluated. The intrinsic neurons were grouped in cluster-like shapes in ovarian structures. In senescent rats, the intrinsic neurons were mainly localized in the ovarian stroma and around the cysts. The number of neurons was lower in senescent rats than in young adult rats (p < 0.05), but the soma size was larger than in young adult rats. Immunoreactivity to TH indicated the presence of noradrenergic neurons in the ovary with the same characteristics as NeuN/β-tubulin, which indicates that they are part of the same neuronal group. Taken together, the findings indicate that the intrinsic neurons may be related to the loss of ovarian functions associated with aging.

Pulsed EMF stimulation increased BDNF and activated S6 levels in the hippocampus of senescent rats

Abstract Purpose Low-frequency electromagnetic field (EMF) exposure in rat has positive effects on neuronal processes in vitro. Moreover, EMF improves learning-memory and psychomotor activity during advanced ageing, but the underlying molecular mechanisms are not known in the brain. In the present study we aimed to investigate the molecular effects of chronic EMF stimulation in the hippocampus of senescent rats in vivo. Materials/Methods Thirty months old rats were treated for six weeks with different EMF doses of 45, 95, and 1,250 µT. After sacrifice the levels of Brain Derived Neurotrophic Factor (BDNF) and activated ribosomal protein S6 as measures for protein synthesis intensity in the hippocampus were determined by Western blot analysis. Results The results showed that chronic EMF exposure dose dependently increased BDNF and the amount of phosphorylated S6 protein at the highest dose. The effects on the two proteins positively correlated at individual level. The results indicate that EMF exposure may enhance neurotrophic processes indicated by increased BDNF expression in the hippocampus of senescent rats. Increased phosphorylated S6 protein suggests coupling to support molecular regulation of protein synthesis. Conclusions In a broader perspective, these findings may support EMF as a beneficial alternative form of passive exercise in active, exercise-limited, aged individuals.

Abstract WP243: Intraperitoneal Igf1 Treatment Modulates The Chronic Impact Of Ischemic Stroke In Reproductively Senescent Female Rats By Repairing The Gut While Icv-igf-1 Does Not

Background: Our previous studies have shown that reproductively senescent (RS) female rats, who have lower circulating levels of the peptide hormone Insulin-like Growth Factor (IGF-1), display worse outcomes after a stroke event than young adult female rats. ICV administration of IGF-1, decreases infarct volume, improves sensory motor performance, and reduces cytokine levels in the ischemic hemisphere of RS females as compared to vehicle-treated controls. Yet, icv IGF1 administration failed to attenuate peripheral inflammation cognitive decline and depressive behaviors in the chronic phase of stroke. In view of the evidence that stroke induces gut dysbiosis, and that gut dysfunction is implicated in depressive and cognitive behaviors, we hypothesize that, unlike icv administration of IGF-1, which is restricted to the brain, systemic i.p. administration of IGF1 would repair the gut, attenuate peripheral cytokine levels and improve long-term behavior outcomes. Methods: Acyclic middle-aged Sprague Dawley female rats (9-11 mos) were subjected to endothelin-1 induced middle cerebral artery occlusion (MCAo) or sham operation. Animals received IGF1 via i.p. injections 4h post MCAo and 24 h post MCAo, or icv infusions, while controls received vehicle. Sensory motor tests, blood and gut samples were acquired pre and post MCAo. Animals were terminated either in the acute phase (2d) or chronic phase (20d). The latter group was also subject to tests of cognition and depressive-like behavior. Results: In contrast to icv treatment, i.p.-IGF-1 did not reduce infarct volume or acute sensory motor impairment but significantly attenuated circulating levels of TNFα and IL12p70. In addition, ip-IGF-1 significantly attenuated post stroke gut dysmorphology, by preserving villus:crypt ratio and expression of tight junction proteins ZO1 and claudin-2. In addition, i.p. IGF1 treatment attenuated the reduction of social interaction and novel object preference post MCAo. Conclusion: Since long term disability after stroke is correlated with elevated levels of peripheral cytokines, our data suggest that systemic IGF1 may be a better therapeutic option for long term cognitive and depressive behaviors after stroke.

Improving SIRT1 by trehalose supplementation reduces oxidative stress, inflammation, and histopathological scores in the kidney of aged rats.

The aging process leads to progressive loss of kidney function. Sirtuin1 (SIRT1) exerts renoprotective effects by conferring resistance to cellular stresses. Trehalose potentially displayed various beneficial effects to promote health span. In this study, we investigated the effects of trehalose on renal SIRT1 and kidney function in senescent rats. Trehalose (2% w/v) was administrated in drinking water for 1month to male aged rats (24months). Then, the level of SIRT1 mRNA and protein, malondialdehyde, total antioxidant capacity, tumor necrosis factor α as well as parameters related to the function and histology of the kidneys were evaluated. Trehalose supplementation increased the level of SIRT1, whereas alleviated the level of oxidative stress, inflammation, and histopathology scores in senescent tissues. However, trehalose administration did not alter kidney function indices in old rats. Collectively, these findings suggested that trehalose was an effective intervention to ameliorate some aspects of age-associated injury in the old kidneys. PRACTICAL APPLICATIONS: Aging is associated with impairment in renal structure and function. Trehalose is a natural disaccharide, which is widely distributed in many organisms. The consumption of trehalose as a dietary supplement is increasing worldwide. This study showed that trehalose administration to aged rats had renoprotective effects through reducing oxidative stress and inflammation, which was mediated by SIRT1. Our results provide useful information for individuals using this sugar as a supplement.

Chitosan Displays a Potent Caloric Restriction Mimetic Effect in Senescent Rats.

Chitosan is a polysaccharide made up of β1,4-linked d-glucosamine (GlcN) and N-acetyl-GlcN. In this study, we evaluated the possible caloric restriction mimetic (CRM) effect of dietary chitosan on systemic redox status, inflammatory biomarkers, and lipid profile in plasma and erythrocyte samples of d-galactose-induced mimetically aged rats. We found a significant increase (p < 0.05) in the reactive oxygen species, protein carbonyl, fasting glucose, body weight, cholesterol, triglyceride, inflammatory markers-interleukin-6 and tumor necrosis factor-alpha in an accelerated senescent rat model. There was also a significant decrease (p < 0.05) in glutathione, advanced glycation end product in senescent rats. Chitosan treatment increased ferric-reducing antioxidant potential, glutathione, plasma membrane-reduced system in accelerated senescent model of rats. Our finding suggests that chitosan has properties similar to a CRM and can effectively maintain the redox homeostasis during the aging process in rat erythrocytes.

Evaluation of senescent cells in intervertebral discs by lipofuscin staining

Intervertebral disc (IVD) degeneration is considered an important contributor of low back pain, a major age-related disease. Interestingly, an unprecedented high number of senescent cells has been reported in aged and degenerated IVDs, most probably affecting tissue homeostasis. In previous studies classical markers of cellular senescence have been used, such as SA-β-gal staining or p16Ink4a expression. Aim of the presented study was a re-evaluation of the number of senescent IVD cells by using a newly established staining procedure for lipofuscin, based on a Sudan Black-B analogue (GL13), which can be used in fresh, as well as in fixed and embedded tissues. In cultures of senescent rat and human IVD cells both SA-β-gal and GL13 gave similar percentages of senescent cells. Similarly, in fresh tissues from old rats the ratios of senescent cells were high with both detection procedures. Finally, in formalin-fixed and paraffin-embedded tissues from humans, a significant increased number of GL13-positive cells was found in herniated tissues, as compared to apparently normal ones, while similar numbers of p16Ink4a-positive cells were observed. These data confirm the significantly enhanced number of senescent cells in aged and degenerated IVDs, most probably contributing to the degeneration of this tissue.