D-gal Treatment Research Articles

Bitter taste receptors protect against skin aging by inhibiting cellular senescence and enhancing wound healing.

BACKGROUND/OBJECTIVESBitter taste receptors are taste signaling pathway mediators, and are also expressed and function in extra-gustatory organs. Skin aging affects the quality of life and may lead to medical issues. The purpose of this study was to better understand the anti-skin aging effects of bitter taste receptors in D-galactose (D-gal)-induced aged human keratinocytes, HaCaT cells.MATERIALS/METHODSExpressions of bitter taste receptors in HaCaT cells and mouse skin tissues were examined by polymerase chain reaction assay. Bitter taste receptor was overexpressed in HaCaT cells, and D-gal was treated to induce aging. We examined the effects of bitter taste receptors on aging by using β-galactosidase assay, wound healing assay, and Western blot assay.RESULTSTAS2R16 and TAS2R10 were expressed in HaCaT cells and were upregulated by D-gal treatment. TAS2R16 exerted protective effects against skin aging by regulating p53 and p21, antioxidant enzymes, the SIRT1/mechanistic target of rapamycin pathway, cell migration, and epithelial-mesenchymal transition markers. TAS2R10 was further examined to confirm a role of TAS2R16 in cellular senescence and wound healing in D-gal-induced aged HaCaT cells.CONCLUSIONSOur results suggest a novel potential preventive role of these receptors on skin aging by regulating cellular senescence and wound healing in human keratinocyte, HaCaT.

The p53/p21/p16 and PI3K/Akt signaling pathways are involved in the ameliorative effects of maltol on D-galactose-induced liver and kidney aging and injury.

Successive evidence has established that maltol, a flavor-enhancing agent, could provide resistance to oxidative stress-induced tissue injury in various animal models though its benefits for aging-induced liver and kidney injuries are still undetermined. In the present work, for demonstrating maltol's ameliorative effect and probable mechanism against aging-induced liver and kidney injuries, D-galactose (D-Gal)-induced animal in vivo and HEK293 cells in vitro models were established and results demonstrated that long-term D-Gal treatment increases the accumulation of advanced glycation end products (AGEs) in liver and kidney tissues, mitigates cell viability, and arrests the cycle. Interestingly, 4-weeks maltol treatment at 50 and 100 mg/kg activated aging-associated proteins including p53, p21, and p16 followed by inhibiting malondialdehyde (MDA)'s over-production and increasing the levels of antioxidant enzymes. Therefore, decreases in cytochrome P450 E1 (CYP2E1) and 4-hydroxydecene (4-HNE)'s immunofluorescence expression levels are confirmed. Furthermore, maltol improved oxidative stress injury by activating the phosphatidylinositol-3-kinase (PI3K)/protein kinase B (Akt) signaling pathway. In conclusion, the purpose of the present study was to estimate the mechanistic insights into maltol's role as an antioxidant in liver and kidney cell senescence and injury, which will reflect potential of therapeutic strategy for antiaging and aging-related disease treatment.

D‐Galactose‐induced accelerated aging model on human erythrocytes and role of Band 3 protein

Aging is a physiological process that induces several changes in cells and tissues, resulting in a greater risk of disease and death. Though this process has been extensively studied both in vivo and in vitro, including human erythrocytes which are an appropriate model to study aging, the involved pathways have not been fully elucidated. D-Galactose (D-Gal) has been widely used in vitro to model the characteristics of premature aging. Nevertheless, there is few information regarding its effect on Band 3 protein (B3p) in human erythrocytes. Band 3 protein is an anion exchanger, essential to maintain homeostasis of erythrocytes and, in turn, of the whole organism. In the present study, human erythrocytes were treated with high D-Gal concentrations (25-35-50-100 mM) for 24 hours at 25°C, and the rate constant for SO42-uptake through B3p was determined to investigate anion exchange capability. As oxidative damage is associated to aging, lipid peroxidation, membrane sulfhydryl oxidation (-SH groups) and % MetHb (methemoglobin) levels after D-Gal treatment were determined. Moreover, % A1c levels (glycated hemoglobin) and expression levels of B3p have been also measured. Our results suggest that D-Gal (35-50-100 mM) reduces anion exchange capability via B3p, putatively mediated both by -SH groups oxidation and lipid peroxidation of cellular membranes; conversely, neither B3p expression levels nor % MetHb were modified. However, D-Gal increased % A1c, known to crosslink with B3p, and involved in the alteration of anion exchange capability. The present findings show that erythrocytes are a good model to study the impact of aging on cell homeostasis. The D-Gal-induced aging model provokes changes at the erythrocyte's membrane level, altering thus anion exchange capability through B3p. High D-Gal concentrations induce elevation of oxidative stress levels, and successively increase % A1c in human erythrocytes. Our findings contribute to the understanding of mechanisms underlying in vitro-induced aging and provide a useful basis for developing therapeutic strategies to counteract age-related diseases and their oxidative impact on erythrocytes. In this view, future studies are recommended to assay antioxidant molecules and their beneficial effect on B3p function during aging process.

Antioxidant Effect of Polygonatum sibiricum Polysaccharides in D-Galactose-Induced Heart Aging Mice.

Polygonatum sibiricum polysaccharides (PSP), the extract of Polygonatum sibiricum, are demonstrated to exhibit a wide range of pharmacological activities. A recent study reported that PSP alleviated the aging of the kidney and meninges. However, the effect of PSP on heart aging remains unclear. The present study is aimed at investigating the protection of PSP on D-galactose- (D-gal-) induced heart aging. Results showed that irregularly arranged cardiac muscle fibers were observed in heart tissues of D-gal-treated mice, and the levels of cardiac troponin T (cTnT), creatine kinase (CK), p21, and p53 were increased after D-gal treatment. D-gal-induced heart aging and injury can be attenuated by oral administration of PSP. Moreover, PSP also decreased reactive oxygen species (ROS) and malondialdehyde (MDA) and increased the level of superoxide dismutase (SOD) in the hearts of D-gal-treated mice. DNA damages and lipid peroxidation induced by oxidative stress were also inhibited by PSP as indicated by reduced levels of 8-hydroxydeoxyguanosine (8-OHdG) and 4-hydroxy-2-nonenal (4-HNE). Collectively, PSP attenuated D-gal-induced heart aging via inhibiting oxidative stress, suggesting that PSP might serve as a potential effective Chinese herbal active constituent for antiaging therapy.

Taxifolin retards the D-galactose-induced aging process through inhibiting Nrf2-mediated oxidative stress and regulating the gut microbiota in mice.

Aging and aging-related metabolic complications are global problems that seriously threaten public health. Taxifolin (TAX) is a novel health food and has been widely proved to have a variety of biological activities used in food and medicine. However, the delayed effect of TAX on the aging process has not been investigated. The purpose of this study is to explore the role of TAX as a natural active substance on aging brain tissue induced by D-galactose (D-Gal) and to determine the effect of supplementing TAX on the metabolism of the intestinal flora in aging bodies. The aging model was established by intraperitoneal injection of D-Gal (800 mg kg-1) once per 3 days for 12 weeks, and TAX (20 and 40 mg kg-1) was administered daily by oral gavage after 6 weeks of induction with D-Gal. After testing aging mice in an eight-arm maze, the results showed that TAX treatment significantly restored spatial learning and memory impairment. Moreover, long-term D-Gal treatment incited cholinergic dysfunction of aging mice, and H&E staining revealed obvious histopathological damage and structural disorder in the hippocampus of mouse brain tissue, while TAX treatment significantly reversed these changes. Importantly, supplementing with TAX significantly mitigated oxidative stress injury by alleviating the levels of reactive oxygen species (ROS) and malondialdehyde (MDA) while increasing antioxidant enzymes. Furthermore, TAX decreased the apoptosis of the aging brain by regulating the phosphorylation levels of phosphatidylinositol 3-kinase (PI3K), protein kinase B (AKT), and activating nuclear factor-erythroid 2-related factor 2 (Nrf2), nuclear heme oxygenase-1 (HO-1), and NADH dehydrogenase quinone 1 (NQO1) to maximally moderate the oxidative stress injury that occurred after D-Gal induction. In addition, 16S rDNA analysis revealed that TAX treatment decelerated the D-gal-induced aging process by regulating the composition of the intestinal flora and abundance of beneficial bacteria, including Enterorhabdus, Clostridium, Bifidobacterium, and Parvibacter. In conclusion, the results of this study demonstrated that TAX alleviated oxidative stress injury in mice aged by D-Gal and also confirmed that TAX improved the aging process by regulating intestinal microbes, which provides the possibility of prevention and treatment for aging and metabolic disorders through the potential food health factors.

Hydrogen Sulfide Restored the Diurnal Variation in Cardiac Function of Aging Mice.

The present study was performed to investigate whether H2S could restore the diurnal variation in cardiac function of aging mice and explore the potential mechanisms. We found that ejection fraction (EF) and fractional shortening (FS) in 3-month-old mice exhibited diurnal variations over a 24-hour period. However, the diurnal variations were disrupted in 18-month-old mice, and there was a decline in EF and FS. In addition, the plasma malondialdehyde (MDA) levels were increased, and H2S concentrations and superoxide dismutase (SOD) activities were decreased in 18-month-old mice. Then, CSE KO mice were used to determine if there was a relationship between endogenous H2S and diurnal variations in EF and FS. There was no difference in 12-hour averaged EF and FS between dark and light periods in CSE KO mice accompanying increased MDA levels and decreased SOD activities in plasma, indicating that deficiency of endogenous H2S blunted diurnal variations of cardiac function. To determine whether oxidative stress disrupted the diurnal variations in cardiac function, D-galactose-induced subacute aging mice were employed. After 3-month D-gal treatment, both 12-hour averaged EF and FS in dark or light periods were decreased; meanwhile, there was no difference in 12-hour averaged EF and FS between dark and light periods. After 3-month NaHS treatment in the D-gal group, the plasma MDA levels were decreased and SOD activities were increased. The EF and FS were lower during the 12-hour light period than those during the 12-hour dark period which was fit to sine curves in the D-gal+NaHS group. Identical findings were also observed in 18-month-old mice. In conclusion, our studies revealed that the disrupted diurnal variation in cardiac function was associated with increased oxidative stress and decreased H2S levels in aging mice. H2S could restore the diurnal variation in cardiac function of aging mice by reducing oxidative stress.

Resveratrol ameliorates thymus senescence changes in D-galactose induced mice.

The thymic microenvironment plays an important role in the development of T cells. A decrease of thymic epithelial cells is the main cause of age-related thymic atrophy or degeneration. Resveratrol (RSV), a phytoalexin produced from plants, has been shown to inhibit the adverse effects of dietary obesity on the structure and function of the thymus. D-Galactose (D-gal) can induce accelerated aging in mice. In the present study, young mice (2 months old) were injected with D-gal (120 mg/kg/day) for 8 consecutive weeks to construct an accelerated aging model. Compared with normal control mice, the thymus epithelium of the D-gal treated mice had structural changes, the number of senescent cells increased, the number of CD4+ T cells decreased, and CD8+ T cells increased. After RSV administration by gavage for 6 weeks, it was found that RSV improved the surface phenotypes of D-gal treated mice, and recovered thymus function by maintaining the ratio of CD4+ to CD8+ cells. It also indicated that RSV enhanced the cell proliferation and inhibited cell senescence. Increased autoimmune regulator (Aire) expression was present in the RSV treated mice. The lymphotoxin-beta receptor (LTβR) expression also increased. These findings suggested that RSV intake could restore the alterations caused by D-gal treatment in the thymus via stimulation of Aire expression.

Effect of Anoectochilus roxburghii flavonoids extract on H2O2 - Induced oxidative stress in LO2 cells and D-gal induced aging mice model

Ethnopharmacological relevanceAnoectochilus roxburghii (A. roxburghii) is a popular folk medicine in many Asian countries, which has been used traditionally for treatment of some diseases such as diabetes, tumors, hyperlipemia, and hepatitis. The ethanol extract from A. roxburghii was recently shown to exert better ability to scavenge free radicals in vitro and possess antioxidant on natural aging mice in vivo. Aim of the studyThis study is to characterize the chemical composition, and investigate the protective effect of the A. roxburghii flavonoids extract (ARF) against hydrogen peroxide (H2O2)-induced oxidative stress in LO2 cells in vitro and D-galactose (D-gal)-induced aging mice model in vivo, and explore the underlying mechanisms. Materials and methodsThe chemical components of the flavonoids extract fromA. roxburghii were detected by ultraperformance lipid chromatography coupled with quadrupole-time-of-flight mass spectrometry (UPLC-QTOF-MS/MS). H2O2 was used to establish an oxidative stress model in LO2 cells. Cytotoxic and protective effects of ARF on the LO2 cells were determined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method. Moreover, the levels of superoxide dismutase (SOD), glutathione peroxidase (GSH-PX), and malondialdehyde (MDA) in cell supernatants were measured by commercial reagent kits. Kun-Ming mice were induced to aging with D-gal (400 mg/kg, BW) by subcutaneous injection for 58 days. From the 28th day to the 58th day of D-gal treatment, ARF (122.5, 245 and 490 mg/kg, BW) and vitamin E (100 mg/kg, BW) were orally administrated to aging mice once a day for consecutive 30 days. After 25 days of the treatment with ARF, learning and memory were assessed using Morris Water Maze (MWM). At the end of the test period, the animals were euthanized by cervical dislocation, and the levels of SOD, GSH-PX, and MDA in serum, liver homogenates and brain homogenates were measured. The levels of monoamine oxidase (MAO) and acetylcholinesterase (AchE) were determined in brain homogenates. Skin and liver histopathological morphology were observed by H&E staining. Furthermore, antioxidant-related gene expression levels in the liver were carried out by quantitative real-time polymerase chain reaction (qRT-PCR). ResultsNine flavonoids were identified in the extracts of A. roxburghii. In vitro assay, a high concentration of ARF (>612.5 μg/ml) reduced the survival rate and had toxic effects on LO2 cells. In addition, ARF (245 μg/ml, 490 μg/ml) and Vitamin C (200 μg/ml) markedly inhibited generations of MDA and increased activities of SOD, GSH-PX in H2O2-induced LO2 cells supernatants. In vivo assay, ARF (122.5 mg/kg, 245 mg/kg and 490 mg/kg) and Vitamin E (100 mg/kg) not only ameliorated learning and memory ability but also improved skin and liver pathological alterations. Strikingly, ARF significantly decreased MDA and MAO levels, markedly enhanced antioxidant enzyme (SOD and GSH-PX) activities. Further, compared to the D-gal group, ARF could obviously up-regulate glutathione peroxidase-1 (GPx-1) and glutathione peroxidase-4 (GPx-4) mRNA levels. ConclusionsThese findings suggested that ARF protects LO2 cells against H2O2-induced oxidative stress and exerts the potent anti-aging effects in D-gal aging mice model, which may be related to the inhibition of oxidative stress. Flavonoid compounds may contribute to the anti-oxidative capability and modulating aging.

CD38 Deficiency Alleviates D-Galactose-Induced Myocardial Cell Senescence Through NAD+/Sirt1 Signaling Pathway.

Our previous research showed that CD38 played vital roles in Ang-II induced hypertrophy and high fat diet induced heart injury. However, the role of CD38 in heart aging is still unknown. In the present study, we reported that CD38 knockdown significantly protected cardiomyocytes from D-galactose (D-gal)-induced cellular senescence. Cellular senescence was evaluated by β-galactosidase staining, the expressions of genes closely related to aging including p16 and p21, and the ROS production, MDA content and the expressions of oxidant stress related genes were examined by biochemical analysis, Western blot and QPCR. Our results showed that the expression of CD38 was increased in H9c2 cells after D-gal treatment and the expressions of NAMPT and Sirt1 were downregulated in heart tissue from old mice. CD38 knockdown significantly reduced the number of SA-β-gal-positive cells and the expressions of p16 and p21 in H9c2 cells with or without D-gal treatment. The acetylation level of total protein was decreased in CD38 knockdown group, but the expression of Sirt3 was increased in CD38 knockdown group treated with D-gal. In addition, knockdown of CD38 significantly attenuated D-gal induced ROS production, MDA content and NOX4 expression in the cells. Inhibition Sirt1 partially reversed the effects of CD38 knockdown on D-gal induced senescence and oxidative stress. Furthermore, NAD+ supplementation reduced D-gal induced cellular senescence, ROS production and MDA content. The expression of SOD2 was increased and the NOX4 expression was decreased in H9c2 cells after NAD+ supplementation. Taken together, our results demonstrated that CD38 knockdown alleviated D-gal induced cell senescence and oxidative stress via NAD+/Sirt1 signaling pathway.

Maltol (3-Hydroxy-2-methyl-4-pyrone) Slows d-Galactose-Induced Brain Aging Process by Damping the Nrf2/HO-1-Mediated Oxidative Stress in Mice.

Maltol, a maillard reaction product from ginseng (Panax ginseng C. A. Meyer), has been confirmed to inhibit oxidative stress in several animal models. Its beneficial effect on oxidative stress related brain aging is still unclear. In this study, the mouse model of d-galactose (d-Gal)-induced brain aging was employed to investigate the therapeutic effects and potential mechanisms of maltol. Maltol treatment significantly restored memory impairment in mice as determined by the Morris water maze tests. Long-term d-Gal treatment reduced expression of cholinergic regulators, i.e., the cholineacetyltransferase (ChAT) (0.456 ± 0.10 vs 0.211 ± 0.03 U/mg prot), the acetylcholinesterase (AChE) (36.4 ± 5.21 vs 66.5 ± 9.96 U/g). Maltol treatment prevented the reduction of ChAT and AChE in the hippocampus. Maltol decreased oxidative stress levels by reducing levels of reactive oxygen species (ROS) and malondialdehyde (MDA) production in the brain and by elevating antioxidative enzymes. Furthermore, maltol treatment minimized oxidative stress by increasing the phosphorylation levels of phosphatidylinositol-3-kinase (PI3K), protein kinase B (Akt), nuclear factor-erythroid 2-related factor 2 (Nrf2), and hemeoxygenase-1 (HO-1). The above results clearly indicate that supplementation of maltol diminishes d-Gal-induced behavioral dysfunction and neurological deficits via activation of the PI3K/Akt-mediated Nrf2/HO-1 signaling pathway in brain. Maltol might become a potential drug to slow the brain aging process and stimulate endogenous antioxidant defense capacity. This study provides the novel evidence that maltol may slow age-associated brain aging.

Ascorbic Acid Mitigates D-galactose-Induced Brain Aging by Increasing Hippocampal Neurogenesis and Improving Memory Function.

Ascorbic acid is essential for normal brain development and homeostasis. However, the effect of ascorbic acid on adult brain aging has not been determined. Long-term treatment with high levels of D-galactose (D-gal) induces brain aging by accumulated oxidative stress. In the present study, mice were subcutaneously administered with D-gal (150 mg/kg/day) for 10 weeks; from the seventh week, ascorbic acid (150 mg/kg/day) was orally co-administered for four weeks. Although D-gal administration alone reduced hippocampal neurogenesis and cognitive functions, co-treatment of ascorbic acid with D-gal effectively prevented D-gal-induced reduced hippocampal neurogenesis through improved cellular proliferation, neuronal differentiation, and neuronal maturation. Long-term D-gal treatment also reduced expression levels of synaptic plasticity-related markers, i.e., synaptophysin and phosphorylated Ca2+/calmodulin-dependent protein kinase II, while ascorbic acid prevented the reduction in the hippocampus. Furthermore, ascorbic acid ameliorated D-gal-induced downregulation of superoxide dismutase 1 and 2, sirtuin1, caveolin-1, and brain-derived neurotrophic factor and upregulation of interleukin 1 beta and tumor necrosis factor alpha in the hippocampus. Ascorbic acid-mediated hippocampal restoration from D-gal-induced impairment was associated with an enhanced hippocampus-dependent memory function. Therefore, ascorbic acid ameliorates D-gal-induced impairments through anti-oxidative and anti-inflammatory effects, and it could be an effective dietary supplement against adult brain aging.

Protective effects of alpinetin on lipopolysaccharide/d-Galactosamine-induced liver injury through inhibiting inflammatory and oxidative responses

Alpinetin, a type of novel plant flavonoid derived from Alpinia katsumadai Hayata, has been reported to have anti-inflammatory effects. The aim of this investigation was designed to reveal the protective effects of alpinetin on Lipopolysaccharide (LPS)/d-galactosamine (D-Gal)-induced liver injury in mice. Alpinetin (12.5, 25, 50 mg/kg) were given 1 h before LPS and D-Gal treatment. 12 h after LPS and D-Gal treatment, the liver tissues and serum were collected. Our results showed that alpinetin treatment improved liver histology, indicating a marked decrease of inflammatory cell infiltration and restore hepatic lobular architecture. Alpinetin also inhibited liver myeloperoxidase (MPO) activity and malondialdehyde (MDA) level. Furthermore, LPS/D-Gal-induced tumor necrosis factor-α (TNF-α) and Interleukin-1β (IL-1β) production were dose-dependently inhibited by alpinetin. Alpinetin also attenuated LPS/D-Gal-induced expression of phospho-NF-κB p65 and phospho-IκBα. In addition, alpinetin was found to increase the expression of nuclear factor E2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1). In conclusion, these findings suggested that alpinetin inhibited liver injury through inhibiting NF-κB and activating the Nrf2 signaling pathway.

Sulfur dioxide improves endothelial dysfunction by downregulating the angiotensin II/AT1R pathway in D-galactose-induced aging rats.

The aim of this study was to investigate the protective effects of sulfur dioxide (SO2) on the endothelial function of the aorta in D-galactose (D-gal)-induced aging rats. Sprague Dawley rats were randomized into a D-gal group, a D-gal + SO2 group and a control group, then injected with D-gal, D-gal + SO2 donor or equivalent volumes of saline, respectively, for 8 consecutive weeks. After 8 weeks, the mean arterial pressure was significantly increased in the D-gal group, but was lowered by SO2. SO2 significantly ameliorated the endothelial dysfunction induced by D-gal treatment. The vasorelaxant effect of SO2 was associated with the elevated nitric oxide levels and upregulated phosphorylation of endothelial nitric oxide synthase. In the D-gal group, the concentration of angiotensin II in the plasma was significantly increased, but was decreased by SO2. Moreover, levels of vascular tissue hydrogen peroxide (H2O2) and malondialdehyde were significantly lower in SO2-treated groups than those in the D-gal group. Western blot analysis showed that the expressions of oxidative stress-related proteins (the angiotensin II type 1 receptor (AT1R), and nicotinamide adenine dinucleotide phosphate oxidase subunits) were increased in the D-gal group, while they were decreased after treatment with SO2. In conclusion, SO2 attenuated endothelial dysfunction in association with the inhibition of oxidative stress injury and the downregulation of the angiotensin II/AT1R pathway in D-gal-induced aging rats.

Matrine Attenuates D-Galactose-Induced Aging-Related Behavior in Mice via Inhibition of Cellular Senescence and Oxidative Stress.

The present study was designed to evaluate the effects of matrine (MAT) on D-galactose- (D-gal-) induced aging and relative mechanism. Vitamin E at the dose of 100 mg/kg was used as a standard positive control. MAT significantly improved the D-gal-induced recognition and spatial memory impairment in novel object recognition and Y maze tests, and exercise endurance decreased in the weight-loaded swimming test at 2 and 10 mg/kg. We found that D-gal treatment induced noticeably aging-related changes such as reducing thymus coefficients, increasing the pathological injury and cellular senescence of liver, spleen, and hippocampus, as well as an increase in cyclin-dependent kinase inhibitor p16, p19, and p21 gene expression and the interleukin-1β expression in the liver and hippocampus. MAT showed effective protection on such changes. Furthermore, MAT decreased the oxidative stress of the liver, plasma, and brain, as evidenced by increased total antioxidant capacity, total superoxide dismutase, and catalase activities and decreased the malondialdehyde level. Additionally, there was a significant positive correlation between swimming time in weight-loaded swimming time and thymus index. MAT ameliorated aging-related disorder caused by D-gal through the inhibition of both cellular senescence and oxidative stress. The study provides further evidence for drug development of MAT for prevention or treatment of the aging-associated disorder.

Memory enhancement and protective effects of crocin against D-galactose aging model in the hippocampus of Wistar rats.

Objective(s):The neurodegeneration and loss of memory function are common consequences of aging. Medicinal plants have potent protective effects against chronic neurodegenerative diseases. The aim of this study was to investigate the beneficial effects and molecular mechanisms of crocin on brain function in D-galactose (D-gal)-induced aging model in rats.Materials and Methods:Male Wistar rats weighing 220 ± 20 g were randomly divided into six groups: control, D-gal (400 mg/kg, SC), D-gal (400 mg/kg) plus crocin (7.5, 15, 30 mg/kg, IP) and crocin alone at dose of 30 mg/kg for 8 weeks. The neuroprotective effects of crocin were evaluated by Morris water maze, determination of malondialdehyde (MDA) levels and Western blot analysis.Results:Crocin significantly inhibited the neurotoxic effects of D-gal through improvement of spatial learning and memory functions as well as the reduction of MDA levels. It was also found that administration of crocin up-regulated pAkt/Akt and pErk/Erk ratio which were decreased by chronic D-gal treatment. In addition, the elevated level of carboxymethyl lysine (CML), as an advance glycation product (AGE), NF-κB p65, TNFα and IL1β significantly decreased in crocin treated rats compared to D-gal group.Conclusion:These findings suggest that crocin is able to enhance memory function in D-gal aging model through anti-glycative and anti-oxidative properties which finally can suppress brain inflammatory mediators (IL-1, TNF and NF-κB) formations and increase PI3K/Akt and Erk/MAPK pathways activity. Therefore, crocin can be considered as healthcare product to prevent age-related brain diseases such as Alzheimer.

Puerarin and Amlodipine Improvement of D-Galactose-Induced Impairments of Behaviour and Neurogenesis in Mouse Dentate Gyrus: Correlation with Glucocorticoid Receptor Expression.

Glucocorticoid receptors (GRs) exert actions on the hippocampus that are important for memory formation. There are correlations between vascular dysfunctions and GR-related gene expression. Both vascular dysfunction and GR gene expression decline occur during the ageing process. Therefore, hypotensors, which have effects on improving vascular dysfunction, may be able to ameliorate GR gene expression decline in ageing mice and improve ageing-mediated memory deficits. In this study, we hypothesized that hypotensors could alleviate the decline of GR gene expression and ameliorate age-induced learning and memory deficits in a D-gal-induced ageing mice model. In line with our hypothesis, we found that chronic D-gal treatment decreased GR and DCX expression in the hippocampus, leading to learning and memory deficits. Amlodipine (AM) and puerarin (PU) treatment improved GR gene expression decline in the hippocampus and ameliorated the learning and memory deficits of D-gal-treated mice. These changes correlated with enhanced DCX expression and brain-derived neurotrophic factor (BDNF) expression in the hippocampus. Furthermore, PU treatment conveyed better effects than AM treatment, but combination therapy did not enhance the effects on improving GR expression. However, we did not find evidence of these changes in non-D-gal-treated mice that lacked GR gene expression decline. These results suggest that AM and PU could improve D-gal-induced behavioural deficits in correlation with GR gene expression.

The oral administration of D-galactose induces abnormalities within the mitochondrial respiratory chain in the brain of rats

D-Galactose (D-gal) chronic administration via intraperitoneal and subcutaneous routes has been used as a model of aging and Alzheimer disease in rodents. Intraperitoneal and subcutaneous administration of D-gal causes memory impairments, a reduction in the neurogenesis of adult mice, an increase in the levels of the amyloid precursor protein and oxidative damage; However, the effects of oral D-gal remain unclear. The aim of this study was to evaluate whether the oral administration of D-gal induces abnormalities within the mitochondrial respiratory chain of rats. Male Wistar rats (4months old) received D-gal (100mg/kg v.o.), during the 1st, 2nd, 4th, 6th or 8th weeks by oral gavage. The activity of the mitochondrial respiratory chain complexes was measured in the 1st, 2nd, 4th, 6th and 8th weeks after the administration of D-gal. The activity of the respiratory chain complex I was found to have increased in the prefrontal cortex and hippocampus in the 1st, 6th and 8th weeks, while the activity of the respiratory chain complex II increased in the 1st, 2nd, 4th, 6th and 8th weeks within the hippocampus and in the 2nd, 4th, 6th and 8th weeks within the prefrontal cortex. The activity of complex II-III increased within the prefrontal cortex and hippocampus in each week of oral D-gal treatment. The activity of complex IV increased within the prefrontal cortex and hippocampus in the 1st, 2nd, 6th and 8th weeks of treatment. After 4weeks of treatment the activity increased only in hippocampus. In conclusion, the present study showed that the oral administration of D-gal increased the activity of the mitochondrial respiratory chain complexes I, II, II-III and IV in the prefrontal cortex and hippocampus. Furthermore, the administration of D-gal via the oral route seems to cause the alterations in the mitochondrial respiratory complexes observed in brain neurodegeneration.

Localization pattern of visfatin (NAMPT) in d-galactose induced aged rat testis

Aging is a complex irreversible process which leads to decline in body physiology including reproductive activity. Neurological and brain functions defects have been studied in the d-gal induced aging rodent model. However, there is dearth of literature on reproductive aging induced by d-gal treatment. Visfatin is an adipokine which regulates testicular steroidogenesis and its level increases under stress conditions to cope and extend longevity. To the best of our knowledge the expression and localization pattern of visfatin and histological evaluation of d-gal induced aged testis have not been investigated. Thus, we hypothesized that the expression pattern and histoarchitecture of d-gal induced aged testis are impaired. Therefore, the aim of the present study was to elucidate the histopthological, immunohistochemical localization and expression of visfatin in d-gal induced aged testis along with serum testosterone level, sperm count and daily sperm production. The western blot and immunohistochemical results of the present study showed that d-gal treatment decreases visfatin expression in the testis, particularly in the Leydig cell, and decreases serum testosterone level. Further, d-gal treatment decrease in testosterone levels was positively correlated with decreases in Johnsen’s score, mean seminiferous tubule diameter, germinal epithelium height, sperm count and daily sperm production. The multinucleated giant cells showed strong immunostaining for visfatin and suggest the role of visfatin as pro/anti-apoptotic factor. Thus, it can be suggested that visfatin may play an important role in testicular aging by regulating testicular steroidogenesis and spermatogenesis.

Oral administration of d-galactose induces cognitive impairments and oxidative damage in rats

d-Galactose (d-gal) is a reducing sugar that can be used to mimic the characteristics of aging in rodents; however, the effects of d-gal administration by oral route are not clear. Therefore, the aim of this study was to elucidate if the oral administration of d-gal induces cognitive impairments, neuronal loss, and oxidative damage, mimicking an animal model of aging. Male adult Wistar rats (4 months old) received d-gal (100mg/kg) via the oral route for a period of 1, 2, 4, 6 or 8 weeks. The results showed cognitive impairments in the open-field test in the 4th and 6th weeks after d-gal administration, as well as an impairment in spatial memory in the radial maze test after the 6th week of d-gal administration. The results indicated increase of levels of thiobarbituric acid reactive species—TBARS—and carbonyl group content in the prefrontal cortex from the 4th week, and in all weeks of d-gal administration, respectively. An increase in the levels of TBARS and carbonyl group content was observed in the hippocampus over the entire period of d-gal treatment. In the 8th week of d-gal administration, we also observed reductions in synaptophysin and TAU protein levels in the prefrontal cortex. Thus, d-gal given by oral route caused cognitive impairments which were accompanied by oxidative damage. Therefore, these results indicate that orally administered d-gal can induce the behavioral and neurochemical alterations that are observed in the natural aging process. However, oral d-gal effect in rats deserve further studies to be better described.

Glutamine synthetase plays a role in d-galactose-induced astrocyte aging in vitro and in vivo

Astrocytes play multiple roles in physiological and pathological conditions in brain. However, little is known about the alterations of astrocytes in age-related changes, and few aging models of the astrocytes in vitro have been established. Therefore, in the present study, we used d-galactose (D-Gal) to establish astrocyte aging model to explore the alterations of astrocytes in brain aging. We also used 1H nuclear magnetic resonance (1H NMR) spectra to verify the metabolic changes in the cerebral cortex of mice injected with D-gal. The results showed that D-gal (55mM) treatment for 1week induced senescence characteristics in cultured cortical astrocytes. Real-time PCR and western blot analysis showed that the levels of glutamine synthetase (GS) mRNA and protein were strikingly decreased in the cultured senescent astrocytes, and the senescent astrocytes showed less resistance to the glutamate-induced gliotoxicity. The impairments of glutamate–glutamine cycle and astrocytes were also found in the cerebral cortex of mice treatment with D-gal (100mg/kg) for 6weeks, and the level of GS mRNA was also found to be reduced markedly, being consistent with the result obtained from the senescent astrocytes in vitro. These results indicate that astrocyte may be the predominant contributor to the pathogenic mechanisms of D-gal-induced brain aging in mice, and GS might be one of the potential therapeutic targets of the aged brain induced by D-gal.