Chronic systemic D-galactose exposure induces memory loss, neurodegeneration, and oxidative damage in mice: protective effects of R-alpha-lipoic acid

Protective Effect of Ginsenoside Rg1 on Hematopoietic Stem/Progenitor Cells through Attenuating Oxidative Stress and the Wnt/β-Catenin Signaling Pathway in a Mouse Model of d-Galactose-induced Aging

Stem cell senescence is an important and current hypothesis accounting for organismal aging, especially the hematopoietic stem cell (HSC). Ginsenoside Rg1 is the main active pharmaceutical ingredient of ginseng, which is a traditional Chinese medicine. This study explored the protective effect of ginsenoside Rg1 on Sca-1⁺ hematopoietic stem/progenitor cells (HSC/HPCs) in a mouse model of d-galactose-induced aging. The mimetic aging mouse model was induced by continuous injection of d-gal for 42 days, and the C57BL/6 mice were respectively treated with ginsenoside Rg1, Vitamin E or normal saline after 7 days of d-gal injection. Compared with those in the d-gal administration alone group, ginsenoside Rg1 protected Sca-1⁺ HSC/HPCs by decreasing SA-β-Gal and enhancing the colony forming unit-mixture (CFU-Mix), and adjusting oxidative stress indices like reactive oxygen species (ROS), total anti-oxidant (T-AOC), superoxide dismutase (SOD), glutathione peroxidase (GSH-px) and malondialdehyde (MDA). In addition, ginsenoside Rg1 decreased β-catenin and c-Myc mRNA expression and enhanced the phosphorylation of GSK-3β. Moreover, ginsenoside Rg1 down-regulated advanced glycation end products (AGEs), 4-hydroxynonenal (4-HNE), phospho-histone H2A.X (r-H2A.X), 8-OHdG, p16(Ink4a), Rb, p21(Cip1/Waf1) and p53 in senescent Sca-1⁺ HSC/HPCs. Our findings indicated that ginsenoside Rg1 can improve the resistance of Sca-1⁺ HSC/HPCs in a mouse model of d-galactose-induced aging through the suppression of oxidative stress and excessive activation of the Wnt/β-catenin signaling pathway, and reduction of DNA damage response, p16(Ink4a)-Rb and p53-p21(Cip1/Waf1) signaling.

Lignans from Schisandra chinensis ameliorate cognition deficits and attenuate brain oxidative damage induced by D-galactose in rats

The aim of this study was to explore the neuroprotective effects of active compounds from Schisandra chinensis (Trucz.) Baill. (Magnoliaceae) against the D-galactose (D-gal)-induced neurotoxicity in rat. The Wistar rats were subcutaneously injected with D-gal (150 mg/(kg day)) for six weeks and orally administered with water extract or 95 % ethanol extract (partitioned with petroleum ether (PE), chloroform (CF), ethyl acetate (EA) and n-Butanol (NB), respectively) of the fruits of Schisandra chinensis simultaneously. The alteration of cognitive functions was assessed by using Morris water maze and Step-down type passive avoidance test. The results demonstrated that PE fraction was the most effective fraction to ameliorate cognitive deficits. Further biochemical examination indicated that PE could attenuate the activities decreasing of superoxide dismutase (SOD), catalase (CAT), the total antioxidant (T-AOC) induced by D-gal, and maintain the normal levels of glutathione (GSH), malondialdehyde (MDA) and nitric oxide (NO) in the serum, prefrontal cortex, striatum and hippocampus of the brain of related rat, selectively. Meanwhile, the compounds of PE fraction were also identified as mainly lignans, thus, these results suggest that lignans from the PE fraction of Schisandra chinensis represented a potential source of medicine for the treatment of the aging-associated neurodegenerative diseases.

Protective Effects of Liquiritin on the Brain of Rats with Alzheimer's Disease

Background

Alzheimer's disease (AD) is a sort of nerve degenerative disease with clinical manifestation of memory damage and cognitive dysfunction. Its typical pathological change is the abnormal deposition of amyloid-beta (Aβ).

Method

In this study, a rat AD model with liquiritin (LQ) interference was established to observe the effects of LQ on the AD rats' behavioural memory and primary hippocampus cells.

Results

Liquiritin had the effect of improving the rats' learning and memory ability, enhancing the activity of catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in rats' brain tissues, increasing the antioxidant ability, protecting the primary cultured hippocampal neurons and inhibiting the apoptosis induced by Aβ_25-35.

Conclusion

The protective effects of LQ can be related to the enhancement of antioxidase activity and clearance of oxygen radicals.

Bamboo leaf extract improves spatial learning ability in a rat model with senile dementia

Senile dementia (SD) is a syndrome characterized by progressive neurological deterioration. Treatment for the disease is still under investigation. Bamboo leaf extract (B-extract) has been known for its biological efficacy in anti-oxidant and anti-cancer activities. However, study on B-extract for its protection against dementia is very limited. The effect of B-extract on a rat model with SD was examined. B-extract improved spatial learning ability of the dementia rats. The hippocampus of dementia model rats showed reduced levels of acetylcholine (ACh), epinephrine (E), norepinephrine (NE), and dopamine (DA), and increased activities of acetylcholine esterase (AChE) and monoamine oxidase (MAO). Treatment with B-extract 20 mg/(kg·d) for 7 weeks significantly inhibited the enzyme activity compared with untreated dementia rats, and raised the levels of ACh, E, and DA in the hippocampus. In addition, treatment with B-extract elevated the level of γ-aminobutyric acid (GABA), but reduced the level of glutamate (Glu) in the brain. These data suggest that B-extract might be a potential drug in treating impairment of spatial memory in dementia rats by regulating the central neurotransmitter function.

Milk Consumption and Framingham Risk Score: Analysis of the Korea National Health and Nutrition Examination Survey Data (2008-2011)

PURPOSE

The benefit of milk intake remains controversial. The association between milk consumption and Framingham Risk Score (FRS) in a population consuming relatively low amounts of dairy products is undetermined.

MATERIALS AND METHODS

A total of 13736 adults (5718 male and 8018 female) aged 20-80 years from the Korea National Health and Nutrition Examination Survey (2008-2011) were divided into groups according to milk consumption (rarely, monthly, weekly, and daily) and compared according to FRS after relevant variable adjustments.

RESULTS

The mean FRS in males and females were 6.53 and 5.74, respectively. Males who consumed milk daily (15.9%) had a significantly lower FRS than males having milk rarely (31.6%) or monthly (17.4%; p=0.007). Females who consumed milk daily (22.3%) also had significantly lower FRS than rarely (29.8%), monthly (13.8%), or weekly (34%; p=0.001) consumers. In particular, males ≥60 years old who consumed milk daily had a significantly lower FRS than males who consumed less milk (p<0.001). The odds ratio in this age group showed a significant and gradual increase in the weekly [OR=2.15; 95% confidence interval (CI) 1.14-4.03], monthly (OR=2.29; 95% CI 1.15-4.54), and rarely (OR=3.79; 95% CI 2.01-7.14) milk consumption groups when compared with the daily milk consumption group.

CONCLUSION

Milk consumption was associated with a lower FRS in a low milk-consuming population. In particular, daily milk consumption in males over 60 years old may be beneficial for those at risk for cardiovascular disease.

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.

Effects of rhein lysinate on D-galactose-induced aging mice

The aim of the present study was to investigate the anti-aging effects of rhein lysinate (RHL), and to explore its mechanism of action in a D-galactose-induced aging mouse model. Aging was induced by D-galactose (100 mg/kg/day) that was subcutaneously injected to animals for 8 weeks. RHL was simultaneously administered once a day by intragastric gavage. The appetite, mental condition, body weight and organ index of the mice were monitored. Superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities were determined, and the levels of malondialdehyde (MDA) in the liver, kidney and serum were measured by appropriate assay kits. Western blot analysis was used to detect proteins associated with age. The results indicated that RHL may improve the appetite, mental state and organ conditions of the model mice, improve the activities of SOD and GSH-Px, reduce MDA levels and modulate the expression of age-associated proteins (Sirtuin 1, p21 and p16) in D-galactose-induced mice. Therefore, RHL may be effective at suppressing the aging process through a combination of enhancing antioxidant activity, scavenging free radicals and modulating aging-associated gene expression.

Comparative study of perception and processing of socially or sexually significant odor information in male rats with normal or accelerated senescence using fMRI

Olfaction plays an important role in mammals while aging causes olfactory dysfunction. Here the features of olfactory function in aging male rats were studied. We compared brain activity of regions involved in the perception (olfactory bulbs) and processing (cerebral cortex, hippocampus, hypothalamus) of sexually or socially significant odor stimulus with 11.7 T MR-scanner and odor perception using behavioral tests in 5-month old males with normal (Wistar rats) or accelerated senescence (d-galactose-treated Wistar rats (150 mg/kg/day, i.p., 12 weeks) or OXYS rats with hereditary defined accelerated aging). d-galactose-treated Wistar males had altered BOLD-response in the centers processing socially significant odor information and changed patterns of the functional connectivity. We detected no significant changes in the olfactory function of OXYS males probably due to compensatory processes. In saline-treated Wistar rats, the correlation of BOLD-responses to both types of stimuli in the olfactory bulbs and cerebral cortex indicated changes in odor differentiation. Behavioral tests showed no significant differences between groups. However, the time of odor exploration increased in d-galactose-treated males indicating changes in odor recognition. Thus, we first revealed that in animal model of pharmacologically induced aging olfactory dysfunction occurred at the level of the centers processing socially significant odor information while the centers of odor perception (olfactory bulbs) remained unaffected. Alterations observed in Wistar rats chronically treated with saline evidenced the influence of long-term manipulations with experimental animals on olfactory function per se.

The spread of adenoviral vectors to central nervous system through pathway of cochlea in mimetic aging and young rats

There is no definitive conclusion concerning the spread of viral vectors to the brain after a cochlear inoculation. In addition, some studies have reported different distribution profiles of viral vectors in the central auditory system after a cochlear inoculation. Thus, rats were grouped into either a mimetic aging group or a young group and transfected with adenoviral vectors (AdVs) by round window membrane injection. The distribution of AdV in central nervous system (CNS) was demonstrated in the two groups with transmission electron microscopy and immunofluorescence. We found that the AdV could disseminate into the CNS and that the neuronal damage and stress-induced GRP78 expression were reduced after transfection with PGC-1α, as compared with the control vectors, especially in the mimetic aging group. We also found that the host immune response was degraded in CNS in the mimetic aging group after transduction through the cochlea, as compared with the young group. These results demonstrate that viral vectors can disseminate into the CNS through the cochlea. Moreover, mimetic aging induced by D-galactose could facilitate the spread of viral vectors into the CNS from the cochlea. These findings may indicate a new potential approach for gene therapy against age-related diseases in the CNS.

Protective Effect of Alpha Lipoic Acid on Rat Sciatic Nerve Ischemia Reperfusion Damage

BACKGROUND

Alpha lipoic acid is a potent antioxidant that plays numerous roles in human health. This study examined the effect of ALA on rat sciatic nerve ischemia reperfusion damage.

AIMS

Protective effect of alpha lipoic acid (ALA) on sciatic nerve following ischemia-reperfusion in rats was investigated by using light microscopy and biochemical methods. Provided that the protective effect of ALA on sciatic nerve is proven, we think the damage to the sciatic nerve that has already occurred or might occur in patients for various reasons maybe prevented or stopped by giving ALA in convenient doses.

STUDY DESIGN

Animal experiment.

METHODS

Forty-two adult male Sprague-Dawley rats (250-300 grams) were used in this study. Rats were randomly divided into six groups including one control (Group 1), one sham (Group 2), two ischemia-reperfusion (Groups 3 and 4) and two treatment groups (Groups5 and 6). Doses of 60 and 100 mg/kg ALA were given (Group 5 and 6) intra peritoneally twice, 1 and 24 hours before the ischemia to each treatment group. Ischemia was carried out the abdominal aorta starting from the distal part of the renal vein for two hours followed by reperfusion for three hours. In immunohistochemical methods, fibronectin immunoreactivity was analyzed. For biochemical analyses, the tissues were taken in eppendorf microtubes and superoxide dismutase (SOD) and glutathione peroxidase (GSHPx) enzyme activities as well as malondialdehyde (MDA) and nitricoxide (NO) levels were measured.

RESULTS

Fibronectin was observed to have increased significantly in the ischemia group; on the other hand, it was observed to have decreased in parallel to the doses in the ALA groups. Biochemical studies showed that SOD and GSHPx declined with ischemia-reperfusion, but the activities of these enzymes were increased in the treatment groups in parallel with the dose. It was found that increased MDA levels with ischemia-reperfusion were decreased in parallel with ALA dose. There were no statistically significant changes in NO.

CONCLUSION

Increased fibronectin observed after ischemia/reperfusion of rat sciatic nerve is reduced after the administration of ALA. This indicates that the function of fibronectin, to reconnect cut nerve segments and regenerate nerves, is more prominent than its function in tissue healing after ischemia. ALA administered before ischemia decreases MDA and increases SOD and GSHPx. We think that ALA may protect against the pathological changes in ischemic nerve and may be used to devise more efficient treatments.

Neuronal marker recovery after Simvastatin treatment in dementia in the rat brain: in vivo magnetic resonance study

The aim of study was to search for new biomarkers with a magnetic resonance technique to identify the early stages of dementia, induced by D-galactose, and evaluate Simvastatin therapy. Localized proton magnetic resonance spectroscopy measurements showed a significant decrease in the concentration of N-acetylaspartate+N-acetylaspartylglutamate and myo-inositol in the D-galactose group compared to the control group, and, conversely, an increase of N-acetylaspartate+N-acetylaspartylglutamate in the D-galactose/Simvastatin group. Using a saturation transfer experiment, with phosphorus magnetic resonance spectroscopy, we observed a significant elevation of the forward rate constant of the creatine kinase reaction in the brains of the D-galactose group compared to controls, and subsequently, a significant reduction of this reaction in the D-galactose/Simvastatin group. Spatial learning and memory were evaluated using the modified Morris water maze test. The dynamics of the learning process represented by the learning index revealed a significant reduction in learning in the D-galactose group, but the deficits as a consequence of the D-galactose effects were recovered in the D-galactose/Simvastatin group, in which the learning dynamics resembled those of the control group. By determining the thiobarbituric acid reactive substances and total coenzyme Q9 in plasma, we have shown that long-term administration of D-galactose created conditions for oxidative stress, and that the administration of Simvastatin decreased oxidative stress in plasma. Volumetry analyses from the hippocampal area show a reduction in the segmented area in the D-galactose group, compared with the control group, and an enlarged area in the hippocampus in the d-galactose/Simvastatin group.

Age-related cataract and drug therapy: opportunities and challenges for topical antioxidant delivery to the lens

Objectives

The search for anticataract drugs has been continuing for decades; some treatments no longer exist but antioxidants are still of much interest.

Key findings

The primary function of the human lens, along with the cornea, is to refract light so that it is correctly focused onto the retina for optimum image quality. With age, the human lens undergoes morphological, biochemical and physical changes leading to opacification. Age-related or senile cataract is one of the main causes of visual impairment in the elderly; given the lack of access to surgical treatment in many parts of the world, cataract remains a major cause of sight loss. Surgical treatment is the only means of treating cataract; this approach, however, has limitations and complications.

Summary

This review discusses the anatomy and physiology of the lens and the changes that are understood to occur with ageing and cataract formation to identify potential areas for effective therapeutic intervention. Experimental techniques and agents used to induce cataract in animal models, the advantages and disadvantages of potential pharmacological treatments specific barriers to delivery of exogenous antioxidants to the lens and the prospects for future research are discussed.

Overelaborated synaptic architecture and reduced synaptomatrix glycosylation in a Drosophila classic galactosemia disease model

Classic galactosemia (CG) is an autosomal recessive disorder resulting from loss of galactose-1-phosphate uridyltransferase (GALT), which catalyzes conversion of galactose-1-phosphate and uridine diphosphate (UDP)-glucose to glucose-1-phosphate and UDP-galactose, immediately upstream of UDP-N-acetylgalactosamine and UDP-N-acetylglucosamine synthesis. These four UDP-sugars are essential donors for driving the synthesis of glycoproteins and glycolipids, which heavily decorate cell surfaces and extracellular spaces. In addition to acute, potentially lethal neonatal symptoms, maturing individuals with CG develop striking neurodevelopmental, motor and cognitive impairments. Previous studies suggest that neurological symptoms are associated with glycosylation defects, with CG recently being described as a congenital disorder of glycosylation (CDG), showing defects in both N- and O-linked glycans. Here, we characterize behavioral traits, synaptic development and glycosylated synaptomatrix formation in a GALT-deficient Drosophila disease model. Loss of Drosophila GALT (dGALT) greatly impairs coordinated movement and results in structural overelaboration and architectural abnormalities at the neuromuscular junction (NMJ). Dietary galactose and mutation of galactokinase (dGALK) or UDP-glucose dehydrogenase (sugarless) genes are identified, respectively, as critical environmental and genetic modifiers of behavioral and cellular defects. Assaying the NMJ extracellular synaptomatrix with a broad panel of lectin probes reveals profound alterations in dGALT mutants, including depletion of galactosyl, N-acetylgalactosamine and fucosylated horseradish peroxidase (HRP) moieties, which are differentially corrected by dGALK co-removal and sugarless overexpression. Synaptogenesis relies on trans-synaptic signals modulated by this synaptomatrix carbohydrate environment, and dGALT-null NMJs display striking changes in heparan sulfate proteoglycan (HSPG) co-receptor and Wnt ligand levels, which are also corrected by dGALK co-removal and sugarless overexpression. These results reveal synaptomatrix glycosylation losses, altered trans-synaptic signaling pathway components, defective synaptogenesis and impaired coordinated movement in a CG neurological disease model.

Curcumin and hesperidin improve cognition by suppressing mitochondrial dysfunction and apoptosis induced by D-galactose in rat brain

D-galactose, a reducing sugar, induces oxidative stress resulting in alteration in mitochondrial dynamics and apoptosis of neurons. Curcumin and hesperidin are antioxidants possessing multimodal functions; hence, their contribution in minimizing D-galactose induced ageing was assessed in the present study. A week prior to D-galactose treatment (150 mg/kg; s.c. for 56 days), animals were treated with curcumin alone, hesperidin alone and a combination of curcumin (50 and 100 mg/kg; orally) with hesperidin (10 and 25 mg/kg; orally) for 63 days. A naïve control was also maintained. Behavioural studies, tricarboxylic acid cycle enzymes, mitochondrial complexes, protein and lipid oxidation and glutathione levels were assessed in the brain mitochondrial fraction. Western blot analysis of caspase-3, cleaved caspase-3 and histological assessment of the CA1 region of the hippocampus were carried out. D-galactose induced significant cognitive deficits, biochemical changes and histological alterations. Individually, curcumin was more effective than hesperidin in reducing the levels of oxidized lipids, proteins, cleaved caspase-3 expression and mitochondrial enzymes. The combination reduced the expression of cleaved caspase-3, malondialdehyde, improved mitochondrial enzymes and glutathione levels. In combination, curcumin and hesperidin protect the morphological facets and improve biochemical functions of neurons thereby improving cognition.

Astaxanthin alleviates brain aging in rats by attenuating oxidative stress and increasing BDNF levels

Astaxanthin (AST) is a carotenoid pigment which possesses potent antioxidative, anti-inflammatory, and neuroprotective properties. The aim of this study was to investigate whether administration of AST had protective effects on D-galactose-induced brain aging in rats, and further examined its protective mechanisms. The results showed that AST treatment significantly restored the activities of glutathione peroxidase (GSH-PX) and superoxide dismutase (SOD), and increased glutathione (GSH) contents and total antioxidant capacity (T-AOC), but decreased malondialdehyde (MDA), protein carbonylation and 8-hydroxy-2- deoxyguanosine (8-OHdG) levels in the brains of aging rats. Furthermore, AST increased the ratio of Bcl-2/Bax, but decreased the expression of Cyclooxygenase-2 (COX-2) in the brains of aging rats. Additionally, AST ameliorated histopathological changes in the hippocampus and restored brain derived neurotrophic factor (BDNF) levels in both the brains and hippocampus of aging rats. These results suggested that AST could alleviate brain aging, which may be due to attenuating oxidative stress, ameliorating hippocampus damage, and upregulating BDNF expression.

Diabetes and the brain: oxidative stress, inflammation, and autophagy

Diabetes mellitus is a common metabolic disorder associated with chronic complications including a state of mild to moderate cognitive impairment, in particular psychomotor slowing and reduced mental flexibility, not attributable to other causes, and shares many symptoms that are best described as accelerated brain ageing. A common theory for aging and for the pathogenesis of this cerebral dysfunctioning in diabetes relates cell death to oxidative stress in strong association to inflammation, and in fact nuclear factor κB (NFκB), a master regulator of inflammation and also a sensor of oxidative stress, has a strategic position at the crossroad between oxidative stress and inflammation. Moreover, metabolic inflammation is, in turn, related to the induction of various intracellular stresses such as mitochondrial oxidative stress, endoplasmic reticulum (ER) stress, and autophagy defect. In parallel, blockade of autophagy can relate to proinflammatory signaling via oxidative stress pathway and NFκB-mediated inflammation.

Protective effect of Artemisia annua L. extract against galactose-induced oxidative stress in mice

Artemisia annua L. (also called qinghao) has been well known as a source of antimalarial drug artemisinins. In addition, the herb was reported to have in vitro antioxidative activity. The present study investigated the protective effect of aqueous ethanol extract of Qinghao (AA extract) against D-galactose-induced oxidative stress in C57BL/6J mice. Feeding AA extract-containing diet lowered serum levels of malondialdehyde and 8-OH-dG that are biomarkers for lipid peroxidation and DNA damage, respectively. Furthermore, AA extract feeding enhanced the activity of NQO1, a typical antioxidant marker enzyme, in tissues such as kidney, stomach, small intestine, and large intestine. In conclusion, AA extract was found to have antioxidative activity in mouse model.

Ginsenoside Rg1 prevents cognitive impairment and hippocampus senescence in a rat model of D-galactose-induced aging

Neurogenesis continues throughout the lifetime in the hippocampus, while the rate declines with brain aging. It has been hypothesized that reduced neurogenesis may contribute to age-related cognitive impairment. Ginsenoside Rg1 is an active ingredient of Panax ginseng in traditional Chinese medicine, which exerts anti-oxidative and anti-aging effects. This study explores the neuroprotective effect of ginsenoside Rg1 on the hippocampus of the D-gal (D-galactose) induced aging rat model. Sub-acute aging was induced in male SD rats by subcutaneous injection of D-gal (120 mg/kg·d) for 42 days, and the rats were treated with ginsenoside Rg1 (20 mg/kg·d, intraperitoneally) or normal saline for 28 days after 14 days of D-gal injection. In another group, normal male SD rats were treated with ginsenoside Rg1 alone (20 mg/kg·d, intraperitoneally) for 28 days. It showed that administration of ginsenoside Rg1 significantly attenuated all the D-gal-induced changes in the hippocampus, including cognitive capacity, senescence-related markers and hippocampal neurogenesis, compared with the D-gal-treated rats. Further investigation showed that ginsenoside Rg1 protected NSCs/NPCs (neural stem cells/progenitor cells) shown by increased level of SOX-2 expression; reduced astrocytes activation shown by decrease level of Aeg-1 expression; increased the hippocampal cell proliferation; enhanced the activity of the antioxidant enzymes GSH-Px (glutathione peroxidase) and SOD (Superoxide Dismutase); decreased the levels of IL-1β, IL-6 and TNF-α, which are the proinflammatory cytokines; increased the telomere lengths and telomerase activity; and down-regulated the mRNA expression of cellular senescence associated genes p53, p21^Cip1/Waf1 and p19^Arf in the hippocampus of aged rats. Our data provides evidence that ginsenoside Rg1 can improve cognitive ability, protect NSCs/NPCs and promote neurogenesis by enhancing the antioxidant and anti-inflammatory capacity in the hippocampus.

Silybum marianum oil attenuates oxidative stress and ameliorates mitochondrial dysfunction in mice treated with D-galactose

Background:

Silybum marianum has been used as herbal medicine for the treatment of liver disease, liver cirrhosis, and to prevent liver cancer in Europe and Asia since ancient times. Silybum marianum oil (SMO), a by-product of silymarin production, is rich in essential fatty acids, phospholipids, sterols, and vitamin E. However, it has not been very good development and use.

Objective:

In the present study, we used olive oil as a control to investigate the antioxidant and anti-aging effect of SMO in D-galactose (D-gal)-induced aging mice.

Materials and Methods:

D-gal was injected intraperitoneally (500 mg/kg body weight daily) for 7 weeks while SMO was simultaneously administered orally. The triglycerides (TRIG) and cholesterol (CHOL) levels were estimated in the serum. Superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), total antioxidant capacity (T-AOC), monoamine oxidase (MAO), malondialdehyde (MDA), caspase-3, and Bcl-2 were determined in the liver and brain. The activities of Na⁺-K⁺-adenosine triphosphatase (ATPase), Ca²⁺-Mg²⁺-ATPase, membrane potential (ΔΨm), and membrane fluidity of the liver mitochondrial were estimated.

Results:

SMO decreased levels of TRIG and CHOL in aging mice. SMO administration elevated the activities of SOD, GSH-Px, and T-AOC, which are suppressed by aging. The levels of MAO and MDA in the liver and brain were reduced by SMO administration in aging mice. Enzyme linked immunosorbent assay showed that SMO significantly decreased the concentration of caspase-3 and improved the activity of Bcl-2 in the liver and brain of aging mice. Furthermore, SMO significantly attenuated the D-gal induced liver mitochondrial dysfunction by improving the activities of Na⁺-K⁺-ATPase, Ca²⁺-Mg²⁺-ATPase, membrane potential (ΔΨm), and membrane fluidity.

Conclusion:

These results indicate that SMO effectively attenuated oxidative damage and improved apoptosis related factors as well as liver mitochondrial dysfunction in aging mice.

Plasma paraoxonase 1 arylesterase activity in D-galactose-induced aged rat model: correlation with LDL oxidation and redox status

OBJECTIVE

There is much evidence linking the involvement of oxidative stress in the pathogenesis of aging. Paraoxonase 1 (PON1) is an HDL-associated antioxidant enzyme that inhibits the oxidative modification of low-density lipoproteins (LDL). We have investigated the changes in plasma PON1 activity, LDL oxidation, radical scavenging activity and lipid peroxidation in D-galactose-induced aging rat model and also compared the results with 24-month naturally aged rats.

METHOD

Arylesterase activity of PON1, susceptibility of LDL for oxidation, plasma radical scavenging activity and plasma thiobarbituric acid reactive substances (TBARS) were measured in normal control rats (4-months-old control rats subjected to D-galactose-induced experimental aging, and 24-month-old naturally aged rats).

RESULTS

There was a significant decrease in plasma PON1 arylesterase activity in both subcutaneous D-galactose-treated groups and 24-month-old aged rats (P < 0.05, for each). TBARS, an oxidative stress marker, was seen to increase in the experimental groups (P < 0.01). In both subcutaneous galactose-treated and naturally aged rats, there was a significant rise in plasma LDL oxidation (P < 0.05, for each). However, radical scavenging activity was decreased significantly (P < 0.01) in both groups, as compared to control.

CONCLUSIONS

The D-galactose-induced rat model of aging mimics the naturally aged rat with reference to PON1 arylesterase activity and susceptibility to LDL oxidation. The results emphasize the importance of PON1 with respect to aging and its association with redox balance of the body.

Oxidation scrutiny in persuaded aging and chronological aging at systemic redox homeostasis level

BACKGROUND

The effect of the natural aging process on systemic redox homeostasis is previously documented. However, none of the studies specify the effect of experimental aging on systemic redox homeostasis. The purpose of this study is to clarify the ambiguity raised in preliminary reports as to mimetic aging dependency of the type and magnitude of oxidative damage on constituents of plasma.

METHODS

In the current study, we investigated the interrelationship among various groups of the systemic oxidative damage markers such as protein oxidation products (protein carbonyl groups, protein hydroperoxides, advanced oxidation protein products, protein thiol groups), lipid peroxidation products (malondialdehyde, lipid hydroperoxides, conjugated dienes), glycoxidation adducts (advanced glycation end products), and antioxidant capacity (ferric reducing/antioxidant power, Cu,Zn-superoxide dismutase, total thiol, non-protein thiol). All these markers were measured in plasma of mimetically aged (MA) rats (5-month-old rats subjected to d-galactose-induced experimental aging), naturally aged (NA) rats (24-month-old), and their corresponding young controls (YC) (5months old).

RESULTS AND CONCLUSIONS

Our current results show that systemic oxidation markers of the MA group share significant similarities in terms of impaired redox homeostasis with the NA rats and may be considered as a reliable experimental aging model for intravascular aging. Additional methodological studies including d-galactose dosage and application time are warranted to clarify the potential involvement of all these systemic redox variations as mechanistic factors in the development of mimetic aging related intravascular deterioration. Reversing or preventing systemic oxidative damage in experimental and natural aging should therefore be considered the primary target for the development of effective therapeutic strategies to prevent or treat age-related vascular disorders.

Lactobacillus pentosus var. plantarum C29 ameliorates memory impairment and inflammaging in a D-galactose-induced accelerated aging mouse model

Aging is associated with Alzheimer's disease (AD), cardiovascular disease and cancer. Oxidative stress is considered as a major factor that accelerates the aging process. To understand the ability of lactic acid bacteria to ameliorate memory impairment caused by aging, we investigated the effect of Lactobacillus pentosus var. plantarum (C29), which is known to protect against scopolamine-induced memory impairment, on oxidative stress (D-galactose)-induced memory impairment in mice. D-Galactose was subcutaneously injected to 20-week old male C57BL/6J mice for 10 weeks, with oral administration of C29 for the final 5 weeks. Excessive intake of D-galactose not only impaired memory, which was indicated by passive avoidance, Y-maze, and Morris water-maze tasks, but also reduced the expression of brain-derived neurotrophic factor (BDNF) and hippocampal doublecortin (DCX) and the activation of cAMP response element-binding protein (CREB). C29 treatment ameliorated D-galactose-induced memory impairment and reversed the suppression of BDNF and DCX expression and CREB activation. Moreover, C29 decreased the expression of a senescence marker p16 and inflammation markers p-p65, p-FOXO3a, cyclooxygenase (COX)-2, and inducible NO synthase (iNOS). C29 treatment inhibited D-galactose-induced expression of M1 polarization markers tumor necrosis factor-α and arginase II, and attenuated the d-galactose-suppressed expression of M2 markers IL-10, arginase I and CD206. Taken together, these findings suggest that C29 may ameliorate memory impairment and M1 macrophage-polarized inflammation caused by aging.

Comparison of behavioral and biochemical deficits in rats with hereditary defined or D-galactose-induced accelerated senescence: evaluating the protective effects of diosgenin

One of the important factors in aging is oxidative stress and aging-related disturbances are believed be ameliorated by antioxidants. Diosgenin is a bio-active ingredient of dioscorea that is widely used in Chinese medicine, shows anti-oxidant activity and improves some aging-related deficits in senescent and menopausal animals. We compared alterations in behavior, biochemical parameters (plasma levels of the uric acid, creatinine, calcium, phosphate, total cholesterol, low-density lipoprotein cholesterol and triglycerides, and the plasma activity of aminotransferases AST and ALT), and sperm motility in two models of accelerated senescence (d-galactose-induced (150 mg/kg/day, i.p., 57 days) aging in Wistar rats vs. genetically defined in OXYS rats) and examined the protective effects of diosgenin (10 or 50mg/kg/day, p.o., 57 days). Both models had augmented levels of ALT activity indicating hepatopathology. Compared to d-galactose-treated animals, OXYS rats demonstrated profound biochemical alterations (hypocalcemia, hypophosphatemia, and hypocholesterolemia) and behavioral deficits (impaired object recognition, decreased sexual motivation and locomotor activity, retarded learning) that confirmed the difference in the mechanisms of accelerated senescence in these models. We first showed diminished sperm motility in males of both models of accelerated senescence studied. Chronic diosgenin treatment failed to improve biochemical and behavioral disturbances and had some undesirable side effects on body weight and working memory in OXYS rats. However, diosgenin restored moderately decreased sperm motility in d-galactose-treated Wistar males and might be recommended for treatment of mild age-related reproductive dysfunctions.

Long-term oral galactose treatment prevents cognitive deficits in male Wistar rats treated intracerebroventricularly with streptozotocin

Basic and clinical research has demonstrated that dementia of sporadic Alzheimer's disease (sAD) type is associated with dysfunction of the insulin-receptor (IR) system followed by decreased glucose transport via glucose transporter GLUT4 and decreased glucose metabolism in brain cells. An alternative source of energy is d-galactose (the C-4-epimer of d-glucose) which is transported into the brain by insulin-independent GLUT3 transporter where it might be metabolized to glucose via the Leloir pathway. Exclusively parenteral daily injections of galactose induce memory deterioration in rodents and are used to generate animal aging model, but the effects of oral galactose treatment on cognitive functions have never been tested. We have investigated the effects of continuous daily oral galactose (200 mg/kg/day) treatment on cognitive deficits in streptozotocin-induced (STZ-icv) rat model of sAD, tested by Morris Water Maze and Passive Avoidance test, respectively. One month of oral galactose treatment initiated immediately after the STZ-icv administration, successfully prevented development of the STZ-icv-induced cognitive deficits. Beneficial effect of oral galactose was independent of the rat age and of the galactose dose ranging from 100 to 300 mg/kg/day. Additionally, oral galactose administration led to the appearance of galactose in the blood. The increase of galactose concentration in the cerebrospinal fluid was several times lower after oral than after parenteral administration of the same galactose dose. Oral galactose exposure might have beneficial effects on learning and memory ability and could be worth investigating for improvement of cognitive deficits associated with glucose hypometabolism in AD.

Valeriana officinalis extract and its main component, valerenic acid, ameliorate D-galactose-induced reductions in memory, cell proliferation, and neuroblast differentiation by reducing corticosterone levels and lipid peroxidation

Valeriana officinalis is used in herbal medicine of many cultures as mild sedatives and tranquilizers. In this study, we investigated the effects of extract from valerian root extracts and its major component, valerenic acid on memory function, cell proliferation, neuroblast differentiation, serum corticosterone, and lipid peroxidation in adult and aged mice. For the aging model, D-galactose (100 mg/kg) was administered subcutaneously to 6-week-old male mice for 10 weeks. At 13 weeks of age, valerian root extracts (100 mg/kg) or valerenic acid (340 μg/kg) was administered orally to control and D-galactose-treated mice for 3 weeks. The dosage of valerenic acid (340 μg/kg), which is the active ingredient of valerian root extract, was determined by the content of valerenic acid in valerian root extract (3.401±0.066 mg/g) measured by HPLC. The administration of valerian root extract and valerenic acid significantly improved the preferential exploration of new objects in novel object recognition test and the escape latency, swimming speeds, platform crossings, and spatial preference for the target quadrant in Morris water maze test compared to the D-galactose-treated mice. Cell proliferation and neuroblast differentiation were significantly decreased, while serum corticosterone level and lipid peroxidation in hippocampus were significantly increased in the D-galactose-treated group compared to that in the control group. The administration of valerian root extract significantly ameliorated these changes in the dentate gyrus of both control and D-galactose-treated groups. In addition, valerenic acid also mitigated the D-galactose-induced reduction of these changes. These results indicate that valerian root extract and valerenic acid enhance cognitive function, promote cell proliferation and neuroblast differentiation, and reduce serum corticosterone and lipid peroxidation in aged mice.

Antioxidant and anti-fatigue activities of phenolic extract from the seed coat of Euryale ferox Salisb. and identification of three phenolic compounds by LC-ESI-MS/MS

This study investigated the antioxidant potential and anti-fatigue effects of phenolics extracted from the seed coat of Euryale ferox Salisb. The in vitro antioxidant potentials, including scavenging DPPH, hydroxyl radical activities and reducing power were evaluated. Antioxidant status in vivo was analyzed by SOD, CAT, GSH-Px activities and the MDA content in liver and kidneys of D-galactose-induced aging mice. The anti-fatigue effect was evaluated using an exhaustive swimming test, along with the determination of LDH, BUN and HG content. The phenolic extract possessed notable antioxidant effects on DPPH, hydroxyl radical scavenging and reducing power. The mice which received the phenolic extract showed significant increases of SOD, CAT (except for in the kidney), GSH-Px activities, and a decrease of MDA content. The average exhaustive swimming time was obviously prolonged. Meanwhile, increase of LDH content and decrease of BUN content were observed after mice had been swimming for 15 min. The HG storage of mice was improved in the high and middle dose extract groups compared with the normal group. The contents of total phenols and gallic acid of the extract were determined. Three compounds in the extract were identified as 5,7-dihydroxy-2-(3,4,5-trihydroxyphenyl)-chroman-4-one, 5,7,4-trihydroxyflavanone and buddlenol E. These results suggest that the extract of E. ferox is a promising source of natural antioxidants and anti-fatigue material for use in functional foods and medicines.

Repeated administration of PEP-1-Cu,Zn-superoxide dismutase and PEP-1-peroxiredoxin-2 to senescent mice induced by D-galactose improves the hippocampal functions

Oxidative stress initiates age-related reduction in hippocampal neurogenesis and the use of antioxidants has been proposed as an effective strategy to prevent or attenuate the reduction of neurogenesis in the hippocampus. In the present study, we investigated the effects of Cu,Zn-superoxide dismutase (SOD1) and/or peroxiredoxin-2 (PRX2) on cell proliferation and neuroblast differentiation in the dentate gyrus in a model of D-galactose-induced aging model. For this study, we constructed an expression vector, PEP-1, fused PEP-1 with SOD1 or PRX2, and generated PEP-1-SOD1 and PEP-1-PRX2 fusion protein. The aging model was induced by subcutaneous injection of D-galactose (100 mg/kg) to 6-week-old male mice for 10 weeks. PEP-1, PEP-1-SOD1 and/or PEP-1-PRX2 fusion protein was intraperitoneally administered to these mice at 13-week-old once a day for 3 weeks and sacrificed at 30 min after the last administrations. The administration of PEP-1-SOD1 and/or PEP-1-PRX2 significantly improved D-galactose-induced deficits on the escape latency, swimming speeds, platform crossings, spatial preference for the target quadrant in Morris water maze test. In addition, the administration of PEP-1-SOD1 and/or PEP-1-PRX2 ameliorated D-galactose-induced reductions of cell proliferation and neuroblast differentiation in the dentate gyrus and significantly reduced D-galactose-induced lipid peroxidation in the hippocampus. These effects were more prominent in the PEP-1-SOD1-treated group with PEP-1-PRX2. These results suggest that a SOD1 and/or PRX2 supplement to aged mice could improve the memory deficits, cell proliferation and neuroblast differentiation in the dentate gyrus of D-galactose induced aged mice by reducing lipid peroxidation.

Ginkgo biloba leaf extract improves the cognitive abilities of rats with D-galactose induced dementia

Standardized Ginkgo biloba leaf extract has been used in clinical trials for its beneficial effects on brain functions, particularly in dementia. Substantial experimental evidences indicated that Ginkgo biloba leaf extract (EGB) protected neuronal cells from a variety of insults. We investigated the effect of EGB on cognitive ability and protein kinase B (PKB) activity in hippocampal neuronal cells of dementia model rats. Rats received an intraperitoneal injection of D-galactose to induce dementia. Forty-eight Spraque-Dawley rats were randomly divided into six groups, including the control group, D-galactose group (Gal), low-dose EGB group (EGB-L), mid-dose EGB group (EGB-M), high-dose EGB group (EGB-H) and treatment group. The EGB-L, EGB-M and EGB-H groups were administered with EGB and D-galactose simultaneously. Y-maze, cresyl violet staining, TUNEL assays and immunohistochemistry staining were performed to detect learning and memory abilities, morphological changes in the hippocampus, neuronal apoptosis and the expressing level of phospho-PKB, respectively. Rats in the Gal group showed decreased abilities of learning and memory, and hippocampal pyramidal cell layer was damaged, while EGB administration improved learning and memory abilities. The Gal group exhibited many stained, condensed nuclei and micronuclei, either isolated or within the cytoplasm of cells (39.5±1.4). Apoptotic cells decreased in the groups of EGB-L (35.9±0.9), EGB-M (16.8±1.0) and EGB-H (10.1±0.8), and there were statistical significances compared with the Gal group. Immunoreactivity of phospho-PKB was localized diffusely throughout the cytosol of cells in all groups, while the immunoreactivity of the Gal group was weak. EGB significantly attenuated learning and memory impairment in a dose-dependent manner, while it could decrease the nmber of TUNEL-positive cells, and increase the activity of PKB. Our results demonstrated that EGB attenuated memory impairment and cell apoptosis in galactose-induced dementia model rats by activating PKB.

Piperine and curcumin exhibit synergism in attenuating D-galactose induced senescence in rats

Aging is associated with progressive decline in mental abilities and functional capacities. Postmitotic tissues are most vulnerable to alteration due to oxidative damage leading to behavioral and biochemical changes. We hypothesized that the anatomical and functional facets of the brain could be protected with powerful antioxidants such as piperine and curcumin by examining their effects individually and in combination in delaying senescence induced by d-galactose. Young adult male Wistar rats were treated with piperine (12 mg/kg) alone, and curcumin (40 mg/kg) alone; and in combination for a period of 49 days by the oral route with treatment being initiated a week prior to d-galactose (60 mg/kg, i.p.). A control group, d-galactose alone and naturally aged control were also evaluated. Behavioral tests, hippocampal volume, CA1 neuron number, oxidative parameters, formation of lipofuscin like autofluorescent substances, neurochemical estimation, and histopathological changes in CA1 region of hippocampus were established. Our results suggest that the combination exerted a superior response compared to monotherapy as evidenced by improved spatial memory, reduced oxidative burden, reduced accumulation of lipofuscin; improvement in signaling, increase in hippocampal volume and protection of hippocampal neurons. We speculate that the powerful antioxidant nature of both, augmented response of curcumin in the presence of piperine and enhanced serotoninergic signaling was responsible for improved cognition and prevention in senescence.

Effects of alpha-lipoic acid on associative and spatial memory of sham-irradiated and 56Fe-irradiated C57BL/6J male mice

Cranial irradiation with (56)Fe, a form of space radiation, causes hippocampus-dependent cognitive changes. (56)Fe irradiation also increases reactive oxygen species (ROS) levels, which may contribute to these changes. Therefore, we investigated the effects of the antioxidant alpha lipoic acid (ALA) on cognition following sham-irradiation and irradiation. Male mice were irradiated (brain only) with (56)Fe (3 Gy) or sham-irradiated at 6-9 months of age. Half of the mice remained fed a regular chow and the other half of the mice were fed a caloric-matched diet containing ALA starting two-weeks prior to irradiation and throughout cognitive testing. Following cognitive testing, levels of 3-nitrotyrosine (3NT), a marker of oxidative protein stress, and levels of microtubule-associated protein (MAP-2), a dendritic protein important for cognition, were assessed using immunohistochemistry and confocal microscopy. ALA prevented radiation-induced impairments in spatial memory retention in the hippocampal and cortical dependent water maze probe trials following reversal learning. However, in sham-irradiated mice, ALA treatment impaired cortical-dependent novel object recognition and amygdala-dependent cued fear conditioning. There was a trend towards lower 3NT levels in irradiated mice receiving a diet containing ALA than irradiated mice receiving a regular diet. In the hippocampal dentate gyrus of mice on regular diet, irradiated mice had higher levels of MAP-2 immunoreactivity than sham-irradiated mice. Thus, ALA might have differential effects on the brain under normal physiological conditions and those involving environmental challenges such as cranial irradiation.

Polycystic ovary syndrome (PCOS)-like phenotypes in the d-galactose-induced aging mouse model

The D-galactose (D-gal)-induced animal model, which is established by consecutive subcutaneous d-gal injections for approximately 6weeks, has been frequently used for aging research. This animal model has been shown to accelerate aging of the brain, kidneys, liver, and blood cells. However, aging of the female reproductive organs in this animal model has not been reported. The aim of this study was to investigate changes in the ovary in the d-gal-induced aging mouse model. First, we evaluated anti-Müllerian hormone (AMH) as a marker of ovarian aging in blood plasma. We speculated there would be lower AMH levels in d-gal-treated mice because ovarian aging would be induced by d-gal, as reported for other tissues. However, the results showed that AMH levels in d-gal-treated mice were approximately four-fold higher than control mice. Abnormally high AMH levels are detected in ovarian cancer and polycystic ovary syndrome (PCOS) patients. Therefore, we examined PCOS-related markers in this mouse model. Total testosterone levels were high and abnormal estrous cycles were induced in d-gal-treated mice. These changes, including AMH levels, in d-gal-treated mice were inhibited by aminoguanidine treatment, an advanced glycation end product reducer. In addition, ovarian cysts were observed in some d-gal-treated mice. These results indicate that with respect to female reproduction, d-gal-treated mice are suitable for PCOS studies, rather than aging studies.

Rutin, a Flavonoid That Is a Main Component of Saussurea involucrata, Attenuates the Senescence Effect in D-Galactose Aging Mouse Model

Saussurea involucrata (Kar. et Kir.), known as the snow lotus, grows in the Tian Shan and A'er Tai areas of China. It has recently been reported that the ethyl acetate extract of S. involucrata (SI-2) can inhibit proliferation and induce apoptosis in PC-3 human prostate cancer cells. This study investigated the protective effect of ethyl acetate extract of S. involucrata (SI-2) or rutin, a flavonoid extracted from ethyl acetate extract of S. involucrata (SI-2), on D-galactose- (D-gal-) induced brain injury in mice. Administering SI-2 or rutin (30 mg/kg/d and 30 mg/kg/d) for 6 weeks, concomitant with D-gal injection, significantly increased superoxide dismutase and glutathione peroxidase activities and decreased the MDA level in plasma. Furthermore, the result showed that the percentages of cleaved caspase-3 and PARP in the D-gal-treated mice were much higher than those in the control. Pretreatment using SI-2 or rutin decreased the expression of cyclooxygenase-2 via downregulation of NF-kappaB, resulting in a decrease in lipid peroxidation. Furthermore, our results also showed that oral administration of rutin to these mice significantly improved behavioral performance in a step-through passive avoidance task and these results suggest that SI-2 or rutin exerts potent antiaging effects on D-gal in mice via antioxidative mechanisms.

NADPH oxidase-dependent oxidative stress and mitochondrial damage in hippocampus of D-galactose-induced aging rats

Mitochondrial DNA (mtDNA) common deletion (CD) plays a significant role in aging and age-related diseases. In this study, we used D-galactose (D-gal) to generate an animal model of aging and the involvement and causative mechanisms of mitochondrial damage in such a model were investigated. Twenty 5-week-old male Sprague-Dawley rats were randomly divided into two groups: D-gal group (n=10) and control group (n=10). The quantity of the mtDNA CD in the hippocampus was determined using a TaqMan real-time PCR assay. Transmission electron microscopy was used to observe the mitochondrial ultrastructure in the hippocampus. Western blot was used to detect the protein levels of NADPH oxidase (NOX) and uncoupling protein 2 (UCP2). We found that the level of mtDNA CD was significantly higher in the hippocampus of D-gal-induced aging rats than in control rats. In comparison with the control group, the mitochondrial ultrastructure in the hippocampus of D-gal-treated rats was damaged, and the protein levels of NOX and UCP2 were significantly increased in the hippocampus of D-gal-induced aging rats. This study demonstrated that the levels of mtDNA CD and NOX protein expression were significantly increased in the hippocampus of D-gal-induced aging rats. These findings indicate that NOX-dependent reactive oxygen species generation may contribute to D-gal-induced mitochondrial damage.