Senescent Mice Research Articles

Resistance Training-induced Decrease In Circulating C1q Is Associated With Attenuated Muscle Degradation In Senescent Mice

Our recent study has showed that reduction of aging-induced elevation of serum C1q level by resistance training was involved in muscle hypertrophy in old adults. C1q activates Wnt/β-catenin in aged muscle, resulting in enhancement of muscle protein degradation-related genes, such as MuRF-1 and Atrogin-1. Although resistance training attenuates muscle protein degradation, it is still unclear that resistance training-induced decrease in serum C1q level is associated with attenuation of muscle protein degradation. PURPOSE: The purpose of this study was to investigate whether resistance training-induced change in circulating C1q level affects muscle protein degradation in senescent mice. METHODS: Male 13-week-old SAMP1 mice (Young) and 38-week-old SAMP1 mice (Aged) were randomly divided into three groups; young-sedentary control (Young-Con), aged-sedentary control (Aged-Con) and aged-resistance training (Aged-RT) groups (n=10 each group). Resistance training was performed 3 days a week for 12 weeks using a climbing ladder with 70% of 1 repetition maximum weight. RESULTS: Muscle strength and mass and cross-sectional area (CSA) of tibialis anterior muscle in the Aged-Con group significantly decreased as compared with the Young-Con group (p<0.05), whereas those in the Aged-RT group significantly increased as compared with the Aged-Con group (p<0.05). Serum C1q level and expression levels of muscle β-catenin, MuRF-1 and Atrogin-1 proteins significantly increased in the Aged-Con group as compared with the Young-Con group (p<0.05), whereas those expression levels in the Aged-RT group significantly decreased as compared with the Aged-Con group (p<0.05). Additionally, serum C1q level was positively correlated with protein expression levels of muscle MuRF-1 (r = 0.713, p<0.05) and Atrogin-1 (r = 0.584, p<0.05), but was negatively correlated with muscle mass (r = -0.469, p<0.05) and CSA (r = -0.595, p<0.01). CONCLUSIONS: These results suggest that resistance training-induced decrease in serum C1q level is associated with attenuation of muscle protein degradation thereby leading to muscle hypertrophy in senescent mice. Supported by Grants-in-Aid for Scientific Research (#17H02182 and #16K13059, M. Iemitsu) and Sasakawa Scientific Research Grant (#29-628 for N. Horii).

Highlights from Recent Cancer Literature

Highlights from Recent Cancer Literature

Senescent Skeletal Muscle Produces a Distinct Cytokine Secretory Profile in Response to Endotoxin Exposure in Vitro

Skeletal muscles are thought to contribute to both pathogen detection and cytokine secretion as a part of the innate immune response. Skeletal muscle fibers contain toll like receptors (TLRs) that bind a wide array of bacterial, viral, and fungal ligands, inducing signal transduction and subsequent cytokine production. Aging populations have significantly greater mortality annually from influenza, incidence of bacterial and fungal infections, and diminished vaccine efficacy. In senescent mice, macrophage TLR expression and cytokine secretion are known to decline in some tissues. It is unknown if skeletal muscle also exhibits age associated changes in innate immune contribution. The objective of this experiment was to determine if there are alterations in cytokine secretory response of aged skeletal muscle to lipopolysaccharide (LPS), a potent TLR2 and TLR4 ligand.Matched solei muscles from 12–15‐week‐old male C57BL/6 mice (n=8; “young”) and 16‐month‐old (n=10; “old”) were excised in oxygenated (95%O2/5%CO2) Krebs solution and placed under 1 g of tension in 2 ml baths at 35°C. After a 30‐min acclimation period (T0), the buffer was changed and muscles were exposed to 1 μg/ml LPS. Bath samples at T0, 1 hr (T1) and 2 hr (T2) were taken, combined with a protease inhibitor cocktail and frozen at −80°C prior to Luminex multiplex analysis.In conclusion, solei from old mice generally displayed a diminished cytokine secretory response, with particularly large decrements in IL‐12p70, IL‐6, MCP‐1, KC, and G‐CSF compared to young controls (see Table 1). Interestingly, solei from old mice displayed relatively large increases in IL‐1α, with smaller, yet also significant increases in IL‐10 and TNFα. The drastically lowered IL‐6 secretion in older mice may diminish the normal inhibition on IL‐1α and subsequent TNFα production. The small rise in IL‐10 in the elder mice may serve as a compensatory mechanism to lower IL‐1α due to diminished IL‐6 response. It may also contribute towards the severely lowered KC production, as is seen with the inhibition of human KC homologue IL‐8 by elevated IL‐10. The combination of radically lower IL‐6 and KC secretion, and increased IL‐1α and TNFα may produce an environment favoring excessive inflammatory, yet reduced chemotactic responses to pathogen exposure in older mice.Support or Funding InformationSupported by NIGMS R01GM118895‐01 and the BK and Betty Stevens Endowment.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Naked mole rats can undergo developmental, oncogene-induced and DNA damage-induced cellular senescence

Cellular senescence is an important anticancer mechanism that restricts proliferation of damaged or premalignant cells. Cellular senescence also plays an important role in tissue remodeling during development. However, there is a trade-off associated with cellular senescence as senescent cells contribute to aging pathologies. The naked mole rat (NMR) (Heterocephalus glaber) is the longest-lived rodent that is resistant to a variety of age-related diseases. Remarkably, NMRs do not show aging phenotypes until very late stages of their lives. Here, we tested whether NMR cells undergo cellular senescence. We report that the NMR displays developmentally programmed cellular senescence in multiple tissues, including nail bed, skin dermis, hair follicle, and nasopharyngeal cavity. NMR cells also underwent cellular senescence when transfected with oncogenic Ras. In addition, cellular senescence was detected in NMR embryonic and skin fibroblasts subjected to γ-irradiation (IR). However, NMR cells required a higher dose of IR for induction of cellular senescence, and NMR fibroblasts were resistant to IR-induced apoptosis. Gene expression analyses of senescence-related changes demonstrated that, similar to mice, NMR cells up-regulated senescence-associated secretory phenotype genes but displayed more profound down-regulation of DNA metabolism, transcription, and translation than mouse cells. We conclude that the NMR displays the same types of cellular senescence found in a short-lived rodent.

Resistance training prevents muscle fibrosis and atrophy via down-regulation of C1q-induced Wnt signaling in senescent mice.

Increased complement component 1q (C1q) secretion with aging leads to muscle fibrosis and atrophy whereas resistance training attenuates circulating C1q levels. This study aimed to clarify whether resistance exercise-induced reduction of C1q secretion contributes to the inhibition of fibrosis and atrophy in aged muscles. Young (13-wk-old) and aged (38-wk-old) senescence-accelerated mouse prone 1 mice were randomly assigned to one of 4 groups: a young or aged sedentary control group, or a young or aged resistance training (climbing a ladder 3 d/wk for 12 wk) group. We found that resistance training ameliorated muscle fibrosis and atrophy in aged mice, concomitant with decreased circulating and muscle C1q levels and attenuated activation of muscle Wnt signaling (glycogen synthase kinase β/β-catenin), including β-catenin in satellite (Pax7+/DAPI+) and fibroblast (vimentin+/DAPI+) cells. Furthermore, during muscle regeneration after mice were injured by cardiotoxin injection, we observed a reduction in circulating C1q levels, the inhibition of muscle fibrosis and repair, and decreased in the activation of muscle cytoplasmic and nuclear β-catenin in aged mice from the resistance training group, but these effects were cancelled by a single preadministration of exogenous recombinant C1q. In addition, resistance training attenuated aging-related muscle loss concomitant with decreased expression of both muscle ring-finger protein 1 and muscle atrophy F-box in the muscle. Thus, resistance training-induced changes in circulating C1q levels may contribute to the prevention of muscle fibrosis and atrophy via muscle Wnt signaling in senescent mice.-Horii, N., Uchida, M., Hasegawa, N., Fujie, S., Oyanagi, E., Yano, H., Hashimoto, T., Iemitsu, M. Resistance training prevents muscle fibrosis and atrophy via down-regulation of C1q-induced Wnt signaling in senescent mice.

Chronic responses of inflammation and macrophage function to exercise training in various tissues of senescence mice

Chronic responses of inflammation and macrophage function to exercise training in various tissues of senescence mice

Dietary Animal Plasma Proteins Improve the Intestinal Immune Response in Senescent Mice.

Increased life expectancy has promoted research on healthy aging. Aging is accompanied by increased non-specific immune activation (inflammaging) which favors the appearance of several disorders. Here, we study whether dietary supplementation with spray-dried animal plasma (SDP), which has been shown to reduce the activation of gut-associated lymphoid tissue (GALT) in rodents challenged by S. aureus enterotoxin B (SEB), and can also prevent the effects of aging on immune system homeostasis. We first characterized GALT in a mouse model of accelerated senescence (SAMP8) at different ages (compared to mice resistant to accelerated senescence; SAMR1). Second, we analyzed the SDP effects on GALT response to an SEB challenge in SAMP8 mice. In GALT characterization, aging increased the cell number and the percentage of activated Th lymphocytes in mesenteric lymph nodes and Peyer’s patches (all, p < 0.05), as well as the expression of IL-6 and TNF-α in intestinal mucosa (both, p < 0.05). With respect to GALT response to the SEB challenge, young mice showed increased expression of intestinal IL-6 and TNF-α, as well as lymphocyte recruitment and activation (all, p < 0.05). However, the immune response of senescent mice to the SEB challenge was weak, since SEB did not change cell recruitment or the percentage of activated Th lymphocytes. Mice supplemented with SDP showed improved capacity to respond to the SEB challenge, similar to the response of the young mice. These results indicate that senescent mice have an impaired mucosal immune response characterized by unspecific GALT activation and a weak specific immune response. SDP supplementation reduces non-specific basal immune activation, allowing for the generation of specific responses.

Effects of Implantation of Cryopreserved Placental Explants on the Behavioral Indices and Morphological Characteristics of the Cerebral Structures in Senescent Mice

The effects of implantation of cryopreserved placental explants (CPEs) on the behavioral phenomena were studied in adult young (6 months old) and in senescent (presenile ontogenetic period, 12 months old) mice; morphological characteristics of the cerebral structures were also examined in these animals. Implantation of CPEs significantly influenced the behavioral indices and adaptational capacities of senescent mice; the direction of such effects was sex-dependent. In male mice, manifestations of deadaptation (decreases in the mobility and exploration habits and an increase in anxiety) were observed, while in females the behavioral manifestations were opposite (positive). Implantation of CPEs led to partial smoothing of negative shifts in the morphological characteristics in the motor cortex and hippocampus of senescent mice. Therefore, CPEs can serve as a source of natural compounds and cell elements providing the activation of neurogenesis, formation of new neurons, and their proliferation in key structures of the brain. In prospect, CPE-based therapeutic agents can be used for the correction of age-related dysfunctions of the CNS.

Protective effect of a phenolic extract containing indoline amides from Portulaca oleracea against cognitive impairment in senescent mice induced by large dose of D-galactose /NaNO2

Ethnopharmacological relevance:Portulaca oleracea L. is a potherb and also a widely used traditional Chinese medicine. In accordance with its nickname “longevity vegetable”, pharmacological study demonstrated that this plant possessed antioxidant, anti-aging, and cognition-improvement function. Active principles pertaining to these functions of P. oleracea need to be elucidated. Aim of the study:The present study evaluated the effect of a phenolic extract (PAAs) from P. oleracea which contained specific antioxidant indoline amides on cognitive impairment in senescent mice. Materials and methods:PAAs was prepared through AB-8 macroporous resin column chromatography. Total phenol content was determined using colorimetric method, and contents of indoline amides were determined using HPLC-UV method. Senescent Kunming mice with cognitive dysfunction were established by intraperitoneal injection of D-galactose (D-gal, 1250mg/kg/day) and NaNO2 (90mg/kg/day) for 8 weeks, L-PAAs (360mg/kg/day), H-PAAs (720mg/kg/day), and nootropic drug piracetam (PA, 400mg/kg/day) as the positive control were orally administered. Spatial learning and memory abilities were evaluated by Morris water maze experiment. Activities of AChE, SOD, CAT, and levels of GSH and MDA in the brain or plasma were measured. Hippocampal morphology was observed by HE staining. Results:Chronic treatment of large dose of D-gal/NaNO2 significantly reduced lifespan, elevated AChE activity, decreased CAT activity, compensatorily up-regulated SOD activity and GSH level, increased MDA level, induced neuronal damage in hippocampal CA1, CA3 and CA4 regions, and impaired cognitive function. Similar to PA, PAAs prolonged the lifespan and improved spatial memory ability. Moreover, PAAs improved learning ability. H-PAAs significantly reversed compensatory increase in SOD activity to the normal level, elevated serum CAT activity, and reduced MDA levels in brain and plasma, more potent than L-PAAs. Besides these, PAAs evidently inhibited hippocampal neuronal damage. However, it had no effect on brain AChE activity. Conclusion:PAAs as the bioactive principles of P. oleracea attenuated oxidative stress, improved survival rate, and enhanced cognitive function in D-gal/NaNO2-induced senile mice, similar to piracetam. This phenolic extract provides a promising candidate for prevention of aging and aging-related cognitive dysfunction in clinic.

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

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

350 - Mutation of the SERCA-Reactive Cysteine-674 to Serine Attenuates Left Ventricular Hypertrophy and Diastolic Dysfunction in Senescent Mice

Background We have shown previously that oxidation of sarcoplasmic reticulum calcium ATPase (SERCA) cysteine-674 was associated with left ventricular (LV) hypertrophy and diastolic dysfunction in senescent mice. In the present study, we tested the hypothesis that mutation of the SERCA-reactive cysteine-674 to serine (C674S), thereby protecting it from oxidation at this site, will attenuate LV hypertrophy and diastolic dysfunction in senescent mice. Methods Young (5-month-old) and senescent (24-month-old) wild-type (WT) or SERCA C674S knock-in (SKI) mice (n=5-8 per group) were studied. We measured LV structure and function by echocardiography, myocyte cross-sectional area by hematoxylin and eosin staining, and myocardial 4-hydroxynonenal (4-HNE) expression by immunohistochemical staining. Results Conventional echocardiography in senescent WT mice demonstrated an increase in LV total wall thickness (TWTh, 1.84±0.05 vs. 1.45±0.03 mm in Young WT) with preserved LV dimension and systolic function. Mitral inflow and tissue Doppler echocardiography in senescent mice showed prolongation of LV isovolumetric relaxation time and deceleration time of early filling in association with decreases in the ratio of peak early-to-late transmitral velocity (E/A ratio, 1.16±0.04 vs. 1.80±0.04 in Young WT) and diastolic myocardial tissue velocity (Em, 18.9±1.5 vs. 26.2±0.5 mm/sec in Young WT), a pattern typical of abnormal relaxation. All of these abnormalities in LV wall thickness and diastolic function were attenuated (p Conclusion Protection of SERCA from oxidation at C674S attenuates aging-induced LV hypertrophy and diastolic dysfunction, suggesting that strategies to protect oxidant target proteins such as SERCA are implicated in preserving diastolic function in the aging heart.

BDA-410 Treatment Reduces Body Weight and Fat Content by Enhancing Lipolysis in Sedentary Senescent Mice.

Loss of muscle mass and force with age leads to fall risk, mobility impairment, and reduced quality of life. This article shows that BDA-410, a calpain inhibitor, induced loss of body weight and fat but not lean mass or skeletal muscle proteins in a cohort of sedentary 23-month-old mice. Food and water intake and locomotor activity were not modified, whereas BDA-410 treatment decreased intramyocellular lipid and perigonadal fat, increased serum nonesterified fatty acids, and upregulated the genes mediating lipolysis and oxidation, lean phenotype, muscle contraction, muscle transcription regulation, and oxidative stress response. This finding is consistent with our recent report that lipid accumulation in skeletal myofibers is significantly correlated with slower fiber-contraction kinetics and diminished power in obese older adult mice. A proteomic analysis and immunoblot showed downregulation of the phosphatase PPP1R12B, which increases phosphorylated myosin half-life and modulates the calcium sensitivity of the contractile apparatus. This study demonstrates that BDA-410 exerts a beneficial effect on skeletal muscle contractility through new, alternative mechanisms, including enhanced lipolysis, upregulation of "lean phenotype-related genes," downregulation of the PP1R12B phosphatase, and enhanced excitation-contraction coupling. This single compound holds promise for treating age-dependent decline in muscle composition and strength.

Racemic oleracein E increases the survival rate and attenuates memory impairment in D-galactose/NaNO2-induced senescent mice

BackgroundCompounds that possess a pyrrolidone skeleton are a rich resource for the discovery of nootropic drugs. Oleracein E (OE), which possesses both tetrahydroisoquinoline and pyrrolidone skeletons, was first isolated from the medicinal plant Portulaca oleracea L. and was thought to be an active component in the cognition-improvement effect induced by this herb. The aim of this study was to investigate the effect of OE on cognitive impairment in senescent mice and its underlying mechanism of action. MethodSenescent Kunming mice were established by the intraperitoneal injection of D-galactose (D-gal, 1250mg/kg/d) and NaNO2 (90mg/kg/d) for 8 weeks. OE (3mg/kg/d, 15mg/kg/d) was orally administered for 8 weeks, and the nootropic drug piracetam (PA, 400mg/kg/d) was used as a positive control. A Morris water maze was used to assess cognitive ability. GSH and MDA levels and T-AOC, SOD, and CAT activities in the brain or plasma were determined. Hippocampal morphology was observed by HE staining, and expression of the anti-apoptotic protein Bcl-2 and the pro-apoptotic proteins Bax and Caspase-3 was observed by immunohistochemical staining. ResultsLarge-dosage treatments with D-gal/NaNO2 for 8 weeks significantly reduced survival, impaired spatial memory capacity, compensatorily up-regulated GSH level and T-AOC and SOD activities, decreased CAT activity, and induced hippocampal neuronal damage and apoptosis as reflected by the apparent low expression of Bcl-2 and high expression of Bax and Caspase-3. OE significantly prolonged lifespan and was more potent than PA. Similar to PA, OE at 15mg/kg/d improved memory capacity. The underlying mechanism of action was related to the reversal of abnormal brain antioxidant biomarkers (GSH, T-AOC, and SOD) to normal levels and the inhibition of hippocampal neuronal apoptosis. ConclusionOE from P. oleracea is an active compound for improving cognitive function and is also a candidate nootropic drug for the treatment of age-related dementia.

Possible role of metal ionophore against zinc induced cognitive dysfunction in D-galactose senescent mice.

Metal ionophores are considered as potential anti-dementia agents, and some are currently undergoing clinical trials. Many metals are known to accumulate and distribute abnormally in the aging brain. Alterations in zinc metal homeostasis in the glutaminergic synapse could contribute to ageing and the pathophysiology of Alzheimer's disease (AD). The present study was designed to investigate the effect of metal ionophores on long term administration of zinc in D-galactose induced senescent mice. The ageing model was established by combined administration of zinc and D-galactose to mice for 6weeks. A novel metal ionophore, PBT-2 was given daily to zinc-induced d-galactose senescent mice. The cognitive behaviour of mice was monitored using the Morris Water Maze. The anti-oxidant status and amyloidogenic activity in the ageing mouse was measured by determining mito-oxidative parameters and deposition of amyloid β (Aβ) in the brain. Systemic administration of both zinc and D-galactose significantly produced memory deficits, mito-oxidative damage, heightened acetylcholinesterase enzymatic activity and deposition of amyloid-β. Treatment with PBT-2 significantly improved behavioural deficits, biochemical profiles, cellular damage, and curbed the deposition of APP in zinc-induced senescent mice. These findings suggest that PBT-2, acting as a metal protein attenuating compound, may be helpful in the prevention of AD or alleviation of ageing.

Dietary Luteolin Reduces Proinflammatory Microglia in the Brain of Senescent Mice.

Brain microglia become dysregulated during aging and express proinflammatory cytokines that play a role in cognitive aging. Recent studies suggest the flavonoid luteolin reduces neuroinflammation and improves learning and memory in aged mice. However, if dietary luteolin reduces microglia activity in the brain of senescent mice is not known. We hypothesized that feeding aged mice a diet with luteolin would reduce microglia activity. Adult (3-6 months) and aged (22-24 months) mice were fed American Institute of Nutrition (AIN)-93M or AIN-93M with luteolin (6 g/kg) for 4 weeks and injected intraperitoneally with saline or lipopolysaccharide (LPS) before microglia were isolated and stained for major histocompatibility complex (MHC) class II, interleukin (IL)-1β, and IL-6 for flow cytometry. In saline-treated mice fed control diet, aging increased the proportion of microglia that stained for MHC class II (<3% for adults vs. 23% for aged), IL-1β (<2% for adults vs. 25% for aged), and IL-6 (<2% for adults vs. 25% for aged), indicating an age-related increase in proinflammatory microglia. In saline-treated aged mice fed luteolin, the proportion of microglia that stained for MHC class II, IL-1β, and IL-6 was reduced by nearly half (to 12%, 13%, and 12%, respectively). Interestingly, luteolin significantly reduced the proportion of microglia that stained for IL-1β and IL-6 in LPS-treated adult mice but not aged. Collectively, the results show that a diet supplemented with luteolin inhibited brain microglia activity during aging and activation by LPS in adults. Therefore, luteolin may inhibit neuroinflammation and improve cognition in the otherwise healthy aged by constraining brain microglia.

Decreased bioavailability of nitric oxide in aorta from ovariectomized senescent mice. Role of cyclooxygenase

This study investigates the effects of aging and/or ovariectomy on vascular reactivity to thromboxane A2 (TXA2) receptor stimulation with U46619, and the modulation by nitric oxide (NO) and cyclooxygenase (COX) in aorta from female senescence-accelerated mice (SAMP8) and from senescence resistant mice (SAMR1). Five-month-old female SAMR1 and SAMP8 were divided into three groups: sham-operated, ovariectomized and ovariectomized plus estradiol. Twenty-eight days after surgery, thoracic aortic rings were mounted for isometric recording of tension and concentration–response curves for U46619 (10−10–3×10−7M) were performed in the absence and in the presence of the NO synthase inhibitor NG-nitro-l-arginine methyl ester (L-NAME, 10−4M) and/or COX inhibitor indomethacin (10−5M). Vascular superoxide production was detected by dihydroethidium staining on sections of thoracic aorta. NO bioavailability in response to U46619 was suppressed by estrogen withdrawn in young and senescent mice and was restored by the administration of estradiol. In the presence of indomethacin, contractions to U46619 decreased in all groups indicating an aging- and estrogen-dependent modulation of contractile prostanoids. The simultaneous incubation of L-NAME and indomethacin did not change the maximal responses and sensitivities to TXA2 in any group in comparison with untreated aortic segments. The superoxide generation induced by TXA2 was greater in aorta from SAMP8 than in SAMR1. Moreover, in ovariectomized groups superoxide production was further increased and treatment with 17β-estradiol reverted the effects of the ovariectomy. Inhibition of COX with indomethacin prevented the U46619-induced increase in superoxide formation. Our results indicate that NO bioavailability in response to TP receptor activation is both estrogen- and aging-dependent. TXA2 induced contractions are partially mediated by COX activation. Both aging and ovariectomy enhanced COX-dependent component of the TXA2-induced contraction. It is noteworthy that in the absence of estrogen, COX inhibition induces an increase of NO bioavailability. Therefore, in senescent female mice with an experimental menopause, TP-receptor stimulation is responsible for COX activation and enhanced superoxide generation, which may result in reduced NO bioavailability. These effects were reversed by estrogen administration.

A dual role of transient receptor potential melastatin 2 channel in cytotoxicity induced by silica nanoparticles.

Silica nanoparticles (NPs) have remarkable applications. However, accumulating evidence suggests NPs can cause cellular toxicity by inducing ROS production and increasing intracellular Ca2+ ([Ca2+]i), but the underlying molecular mechanism is largely unknown. Transient receptor potential melastatin 2 (TRPM2) channel is known to be a cellular redox potential sensor that provides an important pathway for increasing the [Ca2+]i under oxidative stress. In this study, we examined the role of TRPM2 channel in silica NPs-induced oxidative stress and cell death. By quantitation of cell viability, ROS production, [Ca2+]i, and protein identification, we showed that TRPM2 channel is required for ROS production and Ca2+ increase induced by silica NPs through regulating NADPH oxidase activity in HEK293 cells. Strikingly, HEK293 cells expressing low levels of TRPM2 were more susceptible to silica NPs than those expressing high levels of TRPM2. Macrophages from young mice showed significantly lower TRPM2 expression than those from senescent mice and had significantly lower viability after silica NPs exposure than those from senescent ones. Taken together, these findings demonstrate for the first time that TRPM2 channel acts as an oxidative stress sensor that plays a dual role in silica NPs-induced cytotoxicity by differentially regulating the NADPH oxidase activity and ROS generation.

Ameliorative effect of lotus seedpod proanthocyanidins on cognitive impairment and brain aging induced by d-galactose

This study mainly investigated the ameliorative effect of lotus seedpod proanthocyanidins (LSPC) and the mechanism underlying such effect on cognitive impairment and brain aging induced by d-galactose. Aging mice induced by d-galactose (150mg/kg, sc injection daily for 6weeks) were chosen for the experiment. LSPCs (30, 60, and 90mg/kg, ig) were provided after d-galactose injection. Learning and memory functions were detected by Y-maze and step-down avoidance tests. Then, some biochemical indexes related to cognitive ability and aging were measured. Histopathological feature and P53 protein expression in the hippocampus were observed. Results showed that the three different doses of LSPC could significantly ameliorate the learning and memory abilities impaired by d-galactose. LSPC significantly reduced the levels of malondialdehyde and nitric oxide (i.e. 90mg/kg LSPC group vs. model group, P=0.008), reduced the content of β-amyloid peptide 1–42 (i.e. 90mg/kg LSPC group vs. model group, P=0.009), decreased the activities of acetylcholinesterase, monoamine oxidase B, total nitric oxide synthase (i.e. 90mg/kg LSPC group vs. model group, P=0.006), and neuronal nitric oxide synthase and synchronously increased the activities of superoxide dismutase and glutathione peroxidase in the brain. Furthermore, LSPC could prevent neuron damage and could lessen the expression of P53 protein in the hippocampus. These findings demonstrated that LSPC effectively attenuated cognitive damage and improved parameters related to brain aging in senescent mice induced by d-galactose, and may be used to treat Alzheimer's disease.

Remodeling of the intercalated disc related to aging in the mouse heart

BackgroundAging is related to declined cardiac hemodynamic function. As pumping performance may be significantly related to slowed ventricular depolarization and non-synchronous contraction, we hypothesized that aging may cause dysfunction of intercalated disc (ID), which is the structure responsible for intercellular electrical communication between cardiomyocytes. MethodsMale C57BL/6J mice were used for the study at two ages: 4 and 24 months. Electrocardiographic recording was made to analyze the time of ventricular depolarization. Then mice were killed, and the hearts were harvested for examination in transmission electron microscopy (TEM) and immunofluorescence imaging. The expression of connexin 43 (Cx43), N-cadherin, and β-catenin in the myocardium of the left ventricle was evaluated using Western blotting. ResultsIn senescent mice, analysis of averaged QRS complex showed its significant prolongation. At the ultrastructural level, we found frequent disruptions of the ID (affecting 29±5% of them), mainly at the site of adherens junction, with relatively preserved desmosomal intercellular connections and diminished number of gap junctions. Western blotting revealed significantly decreased abundance of Cx43 protein in aged animals, which may cause slowed impulse propagation through the gap junctions and contribute to the observed electrocardiographic alterations. The level of RNA for Cx43 is similar between young and old animals, which suggests a post-transcriptional mechanism of Cx43 protein downregulation. ConclusionsOur study shows age-related disorganization of ID, which may be responsible for slowed conduction of the depolarization wave within the heart, and supports the hypothesis of cardiac dysfunction in senescence.

Effect of flavonoids from Sophora flavescens in aging mice induced by D-galactos

To investigate the effect of flavonoids from Sophora flavescens in aging mice induced by D-galactose and its mechanism. Totally 60 mice were randomly divided into six groups: the control group, the model group, the piracetam group (positive control group) and flavonoids from S. flavescens low, medium and high doses groups. Except for the control group, all of the rest groups were subcutaneously injected with D-galactose (160 mg x kg(-1)) for successively 30 days to establish the sub-acute senescent model. Meanwhile, flavonoids from S. flavescens low, medium and high doses groups were respectively administered with 150, 300 and 600 mg xkg-('1)of flavonoids from S. flavescens for 30 days. The learning and memory abilities of mice were determined by avoiding darkness ex-eriment and jumping stair experiment. The contents of malondialdehyde (MDA) tumor necrosis factor-aα NF-aα the activities of superoxide dismutase (SOD) monoamine oxidase-B (MAO-B) Na'(+)K'(+)-ATPase and Ca2(+ )-ATPase in the brain of mice were deter-ined respectively after the behavioral experiments. The activity of lactic dehydrogenase ( DH) in blood serum was also determined and analyzed by microscope after HE staining to observe the changes in hippocampal organizational structure. Compared with the model group, flavonoids from S. favescens medium and high doses groups showed significantly increases in the latency of avoiding darkness and jumping stair experiments; flavonoids from S. fllvescens low, medium and high doses groups and the piracetam group showed de-reases in the numbers of errors in avoiding darkness experiment; the flavonoids from S. flavescens high dose group and the piracetam group showed reduction- n the number of errors in jumping stair experiment (P <0 . 5 or P <0 . 1). Flavonoids from S. flavescens me-ium and high doses groups and the piracetam group showed improvements in the activities of SOD, Na'(+)K'(+)ATPase in the brain of mice and declines in the contents of MDA and TNF-aα the activity of MAO-B in the brain of mice, the activity of LDH in blood serum (P <0 . 5 or P <0 . 1). Flavonoids from S. flavescens low, medium and high doses groups and the piracetam group also showed im-rovement in the activity of Ca2(+ )ATPase, with statistical difference from the model group (P <0 . 5 or P <0 . 1). The pathological result showed decreases in the number of cells of hippocampal dentate gyrus area, sparse cell arrangement, incomplete cellular mor-hology, scarce cytoplasm, blurred boundary between nucleus and cytoplasm, nuclei anachromasis, irregular pyknosis and unconspicu-us nucleoli in the model group. Compared with the model group, flavonoids from S. flavescens low, medium and high doses groups and the piracetam group showed improvements in hippocampal organization tissues. Flavonoids from S. favescens can improve the learning and memory ability of senescent mice induced by D-galactose. Its mechanism may be correlated with the enhancement of anti-oxidative actions by lowering TNF-aαcontent, which results in the stability of cell membrane and the reduction in MAO-B activity.