Ginkgo biloba extract EGb761 protects against aging-associated mitochondrial dysfunction in platelets and hippocampi of SAMP8 mice

Unveiling the impact of aging on BBB and Alzheimer's disease: Factors and therapeutic implications

Alzheimer's disease (AD) is a highly prevalent neurodegenerative condition that has devastating effects on individuals, often resulting in dementia. AD is primarily defined by the presence of extracellular plaques containing insoluble β-amyloid peptide (Aβ) and neurofibrillary tangles (NFTs) composed of hyperphosphorylated tau protein (P-tau). In addition, individuals afflicted by these age-related illnesses experience a diminished state of health, which places significant financial strain on their loved ones. Several risk factors play a significant role in the development of AD. These factors include genetics, diet, smoking, certain diseases (such as cerebrovascular diseases, obesity, hypertension, and dyslipidemia), age, and alcohol consumption. Age-related factors are key contributors to the development of vascular-based neurodegenerative diseases such as AD. In general, the process of aging can lead to changes in the immune system's responses and can also initiate inflammation in the brain. The chronic inflammation and the inflammatory mediators found in the brain play a crucial role in the dysfunction of the blood-brain barrier (BBB). Furthermore, maintaining BBB integrity is of utmost importance in preventing a wide range of neurological disorders. Therefore, in this review, we discussed the role of age and its related factors in the breakdown of the blood-brain barrier and the development of AD. We also discussed the importance of different compounds, such as those with anti-aging properties, and other compounds that can help maintain the integrity of the blood-brain barrier in the prevention of AD. This review builds a strong correlation between age-related factors, degradation of the BBB, and its impact on AD.

Ginkgo Biloba Extract Can Antagonize Subchronic Arsenite Exposure-Induced Hepatocyte Senescence by Inhibiting Oxidative Damage and Inflammation in Rats

A growing body of evidence suggests that long-term arsenic exposure can induce liver injury. Our previous studies have demonstrated that liver injury occurs in arsenic-poisoning patients and arsenic-exposed rats. However, therapeutic targets are still unclear, and there is a lack of effective drugs. This study aimed to investigate the effects of sodium arsenite (arsenite) exposure on hepatocyte senescence and the intervention effect of ginkgo biloba extract in rats. In this study, 24 male Sprague-Dawley rats (weighing 180-200 g) were randomized into three groups. The control group received a normal diet, and the arsenic-exposed group was given 10 mg/L arsenite for 3 months by free drinking along with a normal diet. The ginkgo biloba extract treatment group was consecutively administered EGb761 (10 mg/kg, by gavage) for 1 month following 2 months of arsenite exposure. Our results showed that exposure to 10 mg/L arsenite induced narrowing of the hepatic sinus space, enlargement of hepatocytes, and increased multinucleated hepatocytes and inflammatory cell infiltration in rat liver tissue compared with the normal control group. Moreover, 10 mg/L arsenite also caused abnormal expression of inflammation-related indices (IL1-β, IL-6, TNF-α), oxidative damage-related indices (SOD, MDA, GPx), and senescence-related proteins (p16, p-p53, E2F1). EGb761 could effectively reduce the pathological damage of liver tissue and antagonize the abnormal expression of liver tissue inflammation and oxidative damage-related indices as well as cellular senescence-related proteins caused by arsenite exposure. Notably, EGb761 reduced the accumulation of arsenic in rat liver tissues. These results suggested that EGb761 could effectively alleviate subchronic arsenic exposure-induced senescence of hepatocytes, which may be achieved partially through inhibiting inflammation and oxidative damage in rats. This study may provide a new therapeutic target for arsenic-induced liver injury.

Caloric Restriction Mitigates Kidney Fibrosis in an Aged and Obese Rat Model

Caloric restriction is an effective intervention to protract healthspan and lifespan in several animal models from yeast to primates, including humans. Caloric restriction has been found to induce cardiometabolic adaptations associated with improved health and to delay the onset and progression of kidney disease in different species, particularly in rodent models. In both aging and obesity, fibrosis is a hallmark of kidney disease, and epithelial-mesenchymal transition is a key process that leads to fibrosis and renal dysfunction during aging. In this study, we used an aged and obese rat model to evaluate the effect of long-term (6 months) caloric restriction (-40%) on renal damage both from a structural and functional point of view. Renal interstitial fibrosis was analyzed by histological techniques, whereas effects on mesenchymal (N-cadherin, Vimentin, Desmin and α-SMA), antioxidant (SOD1, SOD2, Catalase and GSTP1) inflammatory (YM1 and iNOS) markers and apoptotic/cell cycle (BAX, BCL2, pJNK, Caspase 3 and p27) pathways were investigated using Western blot analysis. Our results clearly showed that caloric restriction promotes cell cycle division and reduces apoptotic injury and fibrosis phenotype through inflammation attenuation and leukocyte infiltration. In conclusion, we highlight the beneficial effects of caloric restriction to preserve elderly kidney function.

Changes in levels of the antioxidant glutathione in brain and blood across the age span of healthy adults: A systematic review

Aging is characterized by a gradual decline of the body's biological functions, which can lead to increased production of reactive oxygen species (ROS). Antioxidants neutralize ROS and maintain balance between oxidation and reduction. If ROS production exceeds the ability of antioxidant systems to neutralize, a damaging state of oxidative stress (OS) may exist. The reduced form of glutathione (GSH) is the most abundant antioxidant, and decline of GSH is considered a marker of OS. Our review summarizes the literature on GSH variations with age in healthy adults in brain (in vivo, ex vivo) and blood (plasma, serum), and reliability of in vivo magnetic resonance spectroscopy (MRS) measurement of GSH. A systematic PubMed search identified 35 studies. All in vivo MRS studies (N = 13) reported good to excellent reproducibility of GSH measures. In brain, 3 out of 4 MRS studies reported decreased GSH with age, measured in precuneus, cingulate, and occipital regions, while 1 study reported increased GSH with age in frontal and sensorimotor regions. In post-mortem brain, out of 3 studies, 2 reported decreased GSH with age in hippocampal and frontal regions, while 1 study reported increased GSH with age in a frontal region. Oxidized glutathione disulfide (GSSG) was reported to be increased in caudate with age in 1 study, suggesting OS. Although findings in the brain lacked a clear consensus, the majority of studies suggested a decline of GSH with age. The low number of studies (particularly ex vivo) and potential regional differences may have contributed to variability in the findings in brain. In blood, in contrast, GSH levels predominately were reported to decrease with advancing age (except in the oldest-old, who may represent a select group of particularly successful agers), while GSSG findings lacked consensus. The larger number of studies assessing age-specific GSH level changes in blood (N = 16) allowed for more robust consensus across studies than in brain. Overall, the literature suggests that aging is associated with increased OS in brain and body, but the timing and regional distribution of changes in the brain require further study. The contribution of brain OS to brain aging, and the effect of interventions to raise brain GSH levels on decline of brain function, remain understudied. Given that reliable tools to measure brain GSH exist, we hope this paper will serve as a catalyst to stimulate more work in this field.

Ginkgo Biloba and Long COVID: In Vivo and In Vitro Models for the Evaluation of Nanotherapeutic Efficacy

Coronavirus infections are neuroinvasive and can provoke injury to the central nervous system (CNS) and long-term illness consequences. They may be associated with inflammatory processes due to cellular oxidative stress and an imbalanced antioxidant system. The ability of phytochemicals with antioxidant and anti-inflammatory activities, such as Ginkgo biloba, to alleviate neurological complications and brain tissue damage has attracted strong ongoing interest in the neurotherapeutic management of long COVID. Ginkgo biloba leaf extract (EGb) contains several bioactive ingredients, e.g., bilobalide, quercetin, ginkgolides A-C, kaempferol, isorhamnetin, and luteolin. They have various pharmacological and medicinal effects, including memory and cognitive improvement. Ginkgo biloba, through its anti-apoptotic, antioxidant, and anti-inflammatory activities, impacts cognitive function and other illness conditions like those in long COVID. While preclinical research on the antioxidant therapies for neuroprotection has shown promising results, clinical translation remains slow due to several challenges (e.g., low drug bioavailability, limited half-life, instability, restricted delivery to target tissues, and poor antioxidant capacity). This review emphasizes the advantages of nanotherapies using nanoparticle drug delivery approaches to overcome these challenges. Various experimental techniques shed light on the molecular mechanisms underlying the oxidative stress response in the nervous system and help comprehend the pathophysiology of the neurological sequelae of SARS-CoV-2 infection. To develop novel therapeutic agents and drug delivery systems, several methods for mimicking oxidative stress conditions have been used (e.g., lipid peroxidation products, mitochondrial respiratory chain inhibitors, and models of ischemic brain damage). We hypothesize the beneficial effects of EGb in the neurotherapeutic management of long-term COVID-19 symptoms, evaluated using either in vitro cellular or in vivo animal models of oxidative stress.

Phytotherapeutic targeting of the mitochondria in neurodegenerative disorders

Neurodegenerative diseases are characterized by degeneration or cellular atrophy within specific structures of the brain. Neurons are the major target of neurodegeneration. Neurons utilize 75-80% of the energy produced in the brain. This energy is either formed by utilizing the glucose provided by the cerebrovascular blood flow or by the in-house energy producers, mitochondria. Mitochondrial dysfunction has been associated with neurodegenerative diseases. But recently it has been noticed that neurodegenerative diseases are often associated with cerebrovascular diseases. Cerebral blood flow requires vasodilation which to an extent regulated by mitochondria. We hypothesize that when mitochondrial functioning is disrupted, it is not able to supply energy to the neurons. This disruption also affects cerebral blood flow, further reducing the possibilities of energy supply. Loss of sufficient energy leads to neuronal dysfunction, atrophy, and degeneration. In this chapter, we will discuss the metabolic modifications of mitochondria in aging-related neurological disorders and the potential of phytocompounds targeting them.

Medicinal plants and their secondary metabolites in alleviating knee osteoarthritis: A systematic review

BACKGROUND

With the increasing ages of the general population, the incidence of knee osteoarthritis (KOA) is also rising, and KOA has become a major health problem worldwide. Recently, medicinal plants and their secondary metabolites have gained interest due to their activity in treating KOA. In this paper, a comprehensive systematic review of the literature was performed concerning the effects of medicinal plant extracts and natural compounds against KOA in recent years. The related molecular pathways of natural compounds against KOA were summarized, and the possible crosstalk among components in chondrocytes was discussed to propose possible solutions for the current situation of treating KOA.

PURPOSE

This review focused on the molecular mechanisms by which medicinal plants and their secondary metabolites act against KOA.

METHODS

Literature searches were performed in the PUBMED, Embase, Science Direct, and Web of Science databases for a 10-year period from 2011 to 2022 with the search terms "medicinal plants," "bioactive compounds," "natural products," "phytochemical," "knee osteoarthritis," "knee joint osteoarthritis," "knee osteoarthritis," "osteoarthritis of the knee," and "osteoarthritis of knee joint."

RESULTS

According to the results, substantial plant extracts and secondary metabolites show a positive effect in fighting KOA. Plant extracts and their secondary metabolites can affect the diagnostic and prognostic biomarkers of KOA. Natural products inhibit the expression of MMP1, MMP3, MMP19, syndecan IV, ADAMTS-4, ADAMTS-5, iNOS, COX-2, collagenases, IL-6, IL-1β, and TNF-α in vitro and in vivo and . Cytokines also upregulate the expression of collagen II and aggrecan. The main signaling pathways affected by the extracts and isolated compounds include AMPK, SIRT, NLRP3, MAPKs, PI3K/AKT, mTOR, NF-κB, WNT/β-catenin, JAK/STAT3, and NRF2, as well as the cell death modes apoptosis, autophagy, pyroptosis, and ferroptosis.

CONCLUSION

The role of secondary metabolites in different signaling pathways supplies a better understanding of their potential to develop further curative options for KOA.

Ginkgo biloba: A Treasure of Functional Phytochemicals with Multimedicinal Applications

Ginkgo biloba is an ancient plant species that is thought to provide a variety of health benefits to living organisms and contains plenty of bioactive components, making it a chemically diversified plant. G. biloba has been shown to have a variety of medicinal and pharmacological properties, including anticancer, antidementia, antidiabetic, antiobesity, antilipidemic, antimicrobial, antioxidant, antilipid peroxidation, antiplatelet, anti-inflammatory, hepatoprotective, antidepressant, antiaging, immunomodulatory, antihypertensive, and neuroprotective effects and is frequently used to treat neurological, cardiovascular, and respiratory diseases, such as tardive dyskinesia. Therefore, this review described the therapeutic applications of G. biloba. In addition to describing the therapeutic potential, this review also evaluates the chemical constituents, toxicity, adverse effect, synergistic effect, and the clinical studies of this plant which have been utilized for therapeutic benefits but have demonstrated other consequences. The capacity of G. biloba components to act as free radical scavengers is critical, and combining its extract with other plant extracts has been shown to synergistically boost antioxidant properties. G. biloba used long-term or at high doses that resulted in some adverse effects. Severe drug interactions have also been reported in both animals and humans when combined with other medications. The available data established from both preclinical and clinical studies confirm the potential of G. biloba plant extract in various diseases. Besides, the safety and efficacy of G. biloba continue to require verification through additional experimentation to guide medicinal use.

Ginkgo biloba in the Aging Process: A Narrative Review

Neurodegenerative diseases, cardiovascular disease (CVD), hypertension, insulin resistance, cancer, and other degenerative processes commonly appear with aging. Ginkgo biloba (GB) is associated with several health benefits, including memory and cognitive improvement, in Alzheimer’s disease (AD), Parkinson’s disease (PD), and cancer. Its antiapoptotic, antioxidant, and anti-inflammatory actions have effects on cognition and other conditions associated with aging-related processes, such as insulin resistance, hypertension, and cardiovascular conditions. The aim of this study was to perform a narrative review of the effects of GB in some age-related conditions, such as neurodegenerative diseases, CVD, and cancer. PubMed, Cochrane, and Embase databases were searched, and the PRISMA guidelines were applied. Fourteen clinical trials were selected; the studies showed that GB can improve memory, cognition, memory scores, psychopathology, and the quality of life of patients. Moreover, it can improve cerebral blood flow supply, executive function, attention/concentration, non-verbal memory, and mood, and decrease stress, fasting serum glucose, glycated hemoglobin, insulin levels, body mass index, waist circumference, biomarkers of oxidative stress, the stability and progression of atherosclerotic plaques, and inflammation. Therefore, it is possible to conclude that the use of GB can provide benefits in the prevention and treatment of aging-related conditions.

Enhanced anti-amnestic effect of donepezil by Ginkgo biloba extract (EGb 761) via further improvement in pro-cholinergic and antioxidative activities

ETHNOPHARMACOLOGICAL RELEVANCE

EGb 761 is a standardized dry extract of Ginkgo biloba L. leaves traditionally used by Eastern Asia and has been associated with beneficial effects on neurodegeneration disorders, including Alzheimer's disease.

AIM OF THE STUDY

Since beneficial interactions between EGb 761 and donepezil have been observed in previous clinical studies, the current study was proposed aiming to further explore related mechanisms from both pharmacokinetics and pharmacodynamics aspects.

MATERIALS AND METHODS

Pharmacodynamic interactions were studied in scopolamine-induced cognitive impairment rats received two-weeks treatment of vehicle, EGb 761 and/or donepezil by the Morris water maze test and ex vivo evaluation of biomarkers of cholinergic transmission and oxidative stress in rat brain. In the meantime, pharmacokinetic profiles of donepezil and bilobalide were obtained and compared among all treatment groups. In addition, impact of the bioavailable EGb 761 components on donepezil brain penetration was evaluated with the hCMEC/D3 cell monolayer model.

RESULTS

Scopolamine-induced rats with co-treatment of EGb 761 and donepezil had significantly improved cognitive function in the Morris water maze test with increased brain levels of superoxide dismutase and decreased brain levels of acetylcholinesterase and malondialdehyde than that with treatment of only EGb 761 or donepezil. Despite such beneficial pharmacodynamics outcomes, the two-week co-treatment of EGb 761 and donepezil did not alter the plasma pharmacokinetics and brain uptake of donepezil or bilobalide, which was further verified in the hCMEC/D3 monolayer model.

CONCLUSION

Co-administration of EGb 761 and donepezil exerted better anti-amnestic effect via further enhanced pro-cholinergic and antioxidative effects of EGb 761 or donepezil in scopolamine-induced cognitive impairment rat without alteration in their systemic/brain exposure.

Improving Age-Related Cognitive Decline through Dietary Interventions Targeting Mitochondrial Dysfunction

Aging is inevitable and it is one of the major contributors to cognitive decline. However, the mechanisms underlying age-related cognitive decline are still the object of extensive research. At the biological level, it is unknown how the aging brain is subjected to progressive oxidative stress and neuroinflammation which determine, among others, mitochondrial dysfunction. The link between mitochondrial dysfunction and cognitive impairment is becoming ever more clear by the presence of significant neurological disturbances in human mitochondrial diseases. Possibly, the most important lifestyle factor determining mitochondrial functioning is nutrition. Therefore, with the present work, we review the latest findings disclosing a link between nutrition, mitochondrial functioning and cognition, and pave new ways to counteract cognitive decline in late adulthood through diet.

Platelets transport β-amyloid from the peripheral blood into the brain by destroying the blood-brain barrier to accelerate the process of Alzheimer's disease in mouse models

Extracellular aggregation of the β-amyloid (Aβ) peptide into toxic multimers in the brain is a prominent event occurring in the pathogenesis of Alzheimer's disease (AD), and a large amount of Aβ in the blood is derived from platelets. Thus, we speculated that platelets may play an important role in the process of AD. We first investigated the changes in platelet Aβ secretion with age. Then, we injected platelets from aged amyloid precursor protein APP/PS1 mice into young C57 mice and assessed their memory capacity along with their brain and peripheral blood Aβ expression levels. The Aβ content in mouse platelets increased with age. Exogenously aged APP/PS1 platelets changed the permeability of the blood-brain barrier in vitro, accelerating Aβ deposition in the brain and increasing the Aβ content in peripheral blood, leading to learning and memory deficits in the recipient mice. Subsequently, aspirin was administered to mice as an inhibitor of platelet activation, which effectively alleviated these toxic processes. Finally, we chose an in vitro blood-brain barrier model to explore the possible cytotoxicity of these platelets.

Alzheimer's disease treatment: The share of herbal medicines

One of the most frequent forms of dementia in neurological disorders is Alzheimer's disease (AD). It is a chronic neurodegenerative disease characterized by impaired learning and memory. Pathological symptoms as extracellular amyloid-beta (Aβ) plaques and intracellular accumulation of neurofibrillary tangles occur in AD. Due to the aging of the population and increased prevalence of AD, discovery of new therapeutic agents with the highest effectiveness and fewer side effect seems to be necessary. Numerous synthetic medicines such as tacrine, donepezil, galantamine, rivastigmine, memantine, glutathione, ascorbic acid, ubiquinone, ibuprofen, and ladostigil are routinely used for reduction of the symptoms and prevention of disease progression. Nowadays, herbal medicines have attracted popular attention for numerous beneficial effects with little side effects. Lavandula angustifolia, Ginkgo biloba, Melissa officinalis, Crocus sativus, Ginseng, Salvia miltiorrhiza, and Magnolia officinalis have been widely used for relief of symptoms of some neurological disorders. This paper reviews the therapeutic effects of phytomedicines with prominent effects against various factors implicated in the emergence and progression of AD.

Herbal Medicine for Slowing Aging and Aging-associated Conditions: Efficacy, Mechanisms and Safety

Aging and aging-associated diseases are issues with unsatisfactory answers in the medical field. Aging causes important physical changes which, even in the absence of the usual risk factors, render the cardiovascular system prone to some diseases. Although aging cannot be prevented, slowing down the rate of aging is entirely possible to achieve. In some traditional medicine, medicinal herbs such as Ginseng, Radix Astragali, Ganoderma lucidum, Ginkgo biloba, and Gynostemma pentaphyllum are recognized by the "nourishing of life" and their role as anti-aging phytotherapeutics is increasingly gaining attention. By mainly employing PubMed here we identify and critically analysed 30 years of published studies focusing on the above herbs' active components against aging and aging-associated conditions. Although many plant-based compounds appear to exert an anti-aging effect, the most effective resulted in being flavonoids, terpenoids, saponins, and polysaccharides, which include astragaloside, ginkgolide, ginsenoside, and gypenoside specifically covered in this review. Their effects as antiaging factors, improvers of cognitive impairments, and reducers of cardiovascular risks are described, as well as the molecular mechanisms underlying the above-mentioned effects along with their potential safety. Telomere and telomerase, PPAR-α, GLUTs, FOXO1, caspase-3, bcl-2, along with SIRT1/AMPK, PI3K/Akt, NF-κB, and insulin/insulin-like growth factor-1 pathways appear to be their preferential targets. Moreover, their ability to work as antioxidants and to improve the resistance to DNA damage is also discussed. Although our literature review indicates that these traditional herbal medicines are safe, tolerable, and free of toxic effects, additional well-designed, large-scale randomized control trials need to be performed to evaluate short- and long-term effects and efficacy of these medicinal herbs.

Effect of High-Oleic Peanut Intake on Aging and Its Hippocampal Markers in Senescence-Accelerated Mice (SAMP8)

In many previous studies, the preventive effects of peanut against aging and cognitive impairment have often been unclear, so to clarify the effects we first investigated effective markers for evaluating its effects in the hippocampus of senescence-accelerated mouse prone/8 (SAMP8) mice, mainly using proteomics. The effects of dietary high-oleic peanuts on the hair appearance of SAMP8, the expression of effective markers in the hippocampus, and the TBARS and amino acid contents of the hippocampus were examined. Hippocampus solute carrier family 1 (glial high-affinity glutamate transporter), calcium/calmodulin-dependent protein kinase type II, and sodium- and chloride-dependent GABA transporter, which all are considered to be closely related to glutamic acid concentration were decreased by feeding of the samples, and the GABA/glutamic acid ratio in the hippocampus was increased by feeding with the samples. The formation of glial fibrillary acidic protein and synapsin-2, which showed higher levels in the SAMP8 than in SAMR1, and the protein expression of tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein and dihydropteridine reductase, which are considered to be related to the formation of adrenergic neuron transmitters, were reduced by the feeding of peanuts and their germ-rich fraction. Ferulic acid, as an ester and minor component in peanuts, could be partly connected to the effect of peanuts. These results indicate that high-oleic peanuts and their germ-rich fraction can protect against aging and cognitive impairment by regulating protein expression, which could be measured by the proteomics of the above hippocampus proteins of SAMP8 and the hippocampal GABA/glutamic acid ratio.

Effect of Ginkgo biloba Extract EGb761 on Hippocampal Neuronal Injury and Carbonyl Stress of D-Gal-Induced Aging Rats

Background

Ginkgo biloba extract is widely studied for antiaging activities, but little is known about its antiaging mechanism of protein carbonylation. In order to verify carbonyl toxification (stress) hypothesis of aging, we have investigated the effects of EGb761 on hippocampal neuronal injury and carbonyl stress of aging rats.

Methods

Seventy-two Wister male rats were randomly assigned into six groups (n = 12), normal control (NC), model control (MC), vitamin E (VE, 60 mg/kg) group, EGb761 low doses (GBEL, 8.75 mg/kg), EGb761 moderate doses (GBEM, 17.5 mg/kg), and EGb761 high doses (GBEH, 35 mg/kg). Except the NC, the other groups were subject to subcutaneous administration of 0.5% D-gal (10 ml/kg/day) for 6 weeks to induce aging model. The study detected cognitive impairment in rats by Morris water maze test and the contents of superoxidase dismutase (SOD), malondialdehyde (MDA), total antioxidant capacity (T-AOC) by the related kits. The level of 4-hydroxy-2-nonenal (4-HNE) protein adducts in rat brain was detected, and the ultrastructure of hippocampus was observed.

Results

The EGb761 treatment groups significantly improved the spatial learning and memory of rats. Moreover, EGb761 treatment could reduce hippocampal neuronal damage based on histopathological and ultrastructural observation. Further studies have proved that these activities are remarkably related with the reducing level of MDA, protein carbonyl and lipofuscin, and 4-HNE protein expression, as well as the increasing of SOD and T-AOC content. Furthermore, EGb761 improves telomerase activity by detecting telomerase activity in the brain of aging rats.

Conclusion

Our data indicate that EGb761 is an effective agent against D-gal-induced hippocampal neuronal loss owing to its antioxidative as well as carbonyl stress properties. Meanwhile, the carbonylation hypothesis is confirmed that the high level of 4-HNE may cause age-related neurodegenerative disorders.

Studies on APP metabolism related to age-associated mitochondrial dysfunction in APP/PS1 transgenic mice

The aging brain with mitochondrial dysfunction and a reduced adenosine 5'-triphosphate (ATP) has been implicated in the onset and progression of β-Amyloid (Aβ)-induced neuronal toxicity in AD. To unravel the function of ATP and the underlying mechanisms on AD development, APP/PS1 double transgenic mice and wild-type (WT) C57 mice at 6 and 10 months of age were studied. We demonstrated a decreased ATP release in the hippocampus and platelet of APP/PS1 mice, comparing to C57 mice at a relatively early age. Levels of Aβ were raised in both hippocampus and platelet of APP/PS1 mice, accompanied by a decrease of α-secretase activity and an increase of β-secretase activity. Moreover, our results presented an age-dependent rise in mitochondrial vulnerability to oxidation in APP/PS1 mice. In addition, we found decreased pSer473-Akt levels, increased GSK3β activity by inhibiting phosphorylation at Ser9 in aged APP/PS1 mice and these dysfunctions probably due to down-regulation of Bcl-2 and up-regulation of cleaved caspase-3. Therefore, we demonstrate that PI3K/Akt/GSK3β signaling pathway could be involved in Aβ-associated mitochondrial dysfunction of APP/PS1 mice and APP abnormal metabolism in platelet might provide potential biomarkers for early diagnosis of AD.

The Importance of Natural Antioxidants in the Treatment of Spinal Cord Injury in Animal Models: An Overview

Patients with spinal cord injury (SCI) face devastating health, social, and financial consequences, as well as their families and caregivers. Reducing the levels of reactive oxygen species (ROS) and oxidative stress are essential strategies for SCI treatment. Some compounds from traditional medicine could be useful to decrease ROS generated after SCI. This review is aimed at highlighting the importance of some natural compounds with antioxidant capacity used in traditional medicine to treat traumatic SCI. An electronic search of published articles describing animal models of SCI treated with natural compounds from traditional medicine was conducted using the following terms: Spinal Cord Injuries (MeSH terms) AND Models, Animal (MeSH terms) AND [Reactive Oxygen Species (MeSH terms) AND/OR Oxidative Stress (MeSH term)] AND Medicine, Traditional (MeSH terms). Articles reported from 2010 to 2018 were included. The results were further screened by title and abstract for studies performed in rats, mice, and nonhuman primates. The effects of these natural compounds are discussed, including their antioxidant, anti-inflammatory, and antiapoptotic properties. Moreover, the antioxidant properties of natural compounds were emphasized since oxidative stress has a fundamental role in the generation and progression of several pathologies of the nervous system. The use of these compounds diminishes toxic effects due to their high antioxidant capacity. These compounds have been tested in animal models with promising results; however, no clinical studies have been conducted in humans. Further research of these natural compounds is crucial to a better understanding of their effects in patients with SCI.

Protective Effects of Hydrolyzed Chicken Extract (Probeptigen®/Cmi-168) on Memory Retention and Brain Oxidative Stress in Senescence-Accelerated Mice

The senescence-accelerated prone (SAMP8) mouse model shows age-dependent deterioration in learning and memory and increased oxidative stress in the brain. We previously showed that healthy subjects on a six-week supplementation of a chicken meat hydrolysate (ProBeptigen®/CMI-168) demonstrated enhanced and sustained cognitive performance up until two weeks after the termination of supplementation. In this study, we investigate the effect of ProBeptigen on the progression of age-related cognitive decline. Three-month old SAMP8 mice were orally administered different doses of ProBeptigen (150,300 or 600 mg/kg/day) or saline daily for 13 weeks. Following ProBeptigen supplementation, mice showed lower scores of senescence and improved learning and memory in avoidance tasks. ProBeptigen treatment also increased antioxidant enzyme activity and dopamine level while reducing protein and lipid peroxidation and mitochondrial DNA damage in the brain. Microarray analysis of hippocampus revealed several processes that may be involved in the improvement of cognitive ability by ProBeptigen, including heme binding, insulin growth factor (IGF) regulation, carboxylic metabolic process, oxidation-reduction process and endopeptidase inhibition. Genes found to be significantly altered in both ProBeptigen treated male and female mice include Mup1, Mup17, Mup21, Ahsg and Alb. Taken together, these results suggest a potential anti-aging effect of ProBeptigen in alleviating cognitive deficits and promoting the antioxidant defense system.

Extract of Ginkgo biloba exacerbates liver metastasis in a mouse colon cancer Xenograft model

Background

Metastasis refers to the spread of a primary tumor cell from the primary site to other locations in the body and it is generally associated with the severity of a tumor. Extract of Ginkgo biloba (EGb) contains various bioactive compounds and it exerts beneficial effects including improvements in brain function and reduced risk of cardiovascular diseases. On the other hand, increased risk of thyroid and liver cancers by EGb have been reported in animals.

Methods

A colon cancer metastasis model was established using intrasplenic injection of a human colon cancer cell line, SW620-luc in athymic mice to investigate the potential impact of EGb on colon cancer progression. After tumor establishment, EGb was intraperitonically injected daily for 5 wks.

Results

EGb significantly increased the rate of metastasis in mouse liver and decreased the number of necrotic and apoptotic cells in the metastatic liver when compared to the control. Meanwhile, EGb significantly induced proliferation of tumor cells in the metastatic liver, indicated by increased staining of Ki67 and H3S10p. mRNA expression of genes involved in cell cycle, metastasis, apoptosis, and oxidative stress were altered by EGb treatment in livers with tumors. Moreover, EGb activated the stress-responsive MAPK pathways in the liver with metastatic tumors.

Conclusions

EGb exacerbated liver metastasis in a mouse colon cancer metastasis model. This is potentially due to the increased tumor cell proliferation involving stimulated MAPK pathways.

Electronic supplementary material

The online version of this article (10.1186/s12906-017-2014-7) contains supplementary material, which is available to authorized users.

Advances in the Studies of Ginkgo Biloba Leaves Extract on Aging-Related Diseases

The prevalence of degenerative disorders in public health has promoted in-depth investigations of the underlying pathogenesis and the development of new treatment drugs. Ginkgo biloba leaves extract (EGb) is obtained from Ginkgo biloba leaves and has been used for thousands of years. In recent decades, both basic and clinical studies have established the effects of EGb. It is widely used in various degenerative diseases such as cerebrovascular disease, Alzheimer's disease, macroangiopathy and more. Here, we reviewed several pharmacological mechanisms of EGb, including its antioxidant properties, prevention of mitochondrial dysfunctions, and effect on apoptosis. We also described some clinical applications of EGb, such as its effect on neuro and cardiovascular protection, and anticancer properties. The above biological functions of EGb are mainly focused on aging-related disorders, but its effect on other diseases remains unclear. Thus, through this review, we aim to encourage further studies on EGb and discover more potential applications.

Brain aging and neurodegeneration: from a mitochondrial point of view

Aging is defined as a progressive time-related accumulation of changes responsible for or at least involved in the increased susceptibility to disease and death. The brain seems to be particularly sensitive to the aging process since the appearance of neurodegenerative diseases, including Alzheimer's disease, is exponential with the increasing age. Mitochondria were placed at the center of the 'free-radical theory of aging', because these paramount organelles are not only the main producers of energy in the cells, but also to main source of reactive oxygen species. Thus, in this review, we aim to look at brain aging processes from a mitochondrial point of view by asking: (i) What happens to brain mitochondrial bioenergetics and dynamics during aging? (ii) Why is the brain so sensitive to the age-related mitochondrial impairments? (iii) Is there a sex difference in the age-induced mitochondrial dysfunction? Understanding mitochondrial physiology in the context of brain aging may help identify therapeutic targets against neurodegeneration. This article is part of a series "Beyond Amyloid".

Cognitive-enhancing effects of hydrolysate of polygalasaponin in SAMP8 mice

OBJECTIVES

The aim of the study is to evaluate the cognitive-enhancing effects of hydrolysate of polygalasaponin (HPS) on senescence accelerate mouse P8 (SAMP8) mice, an effective Alzheimer's disease (AD) model, and to research the relevant mechanisms.

METHODS

The cognitive-enhancing effects of HPS on SAMP8 mice were assessed using Morris water maze (MWM) and step-through passive avoidance tests. Then N-methyl-D-aspartate (NMDA) receptor subunit expression for both the cortex and hippocampus of mice was observed using Western blotting.

RESULTS

HPS (25 and 50 mg/kg) improved the escape rate and decreased the escape latency and time spent in the target quadrant for the SAMP8 mice in the MWM after oral administration of HPS for 10 d. Moreover, it decreased error times in the passive avoidance tests. Western blotting showed that HPS was able to reverse the levels of NMDAR1 and NMDAR2B expression in the cortex or hippocampus of model mice.

CONCLUSIONS

The present study suggested that HPS can improve cognitive deficits in SAMP8 mice, and this mechanism might be associated with NMDA receptor (NMDAR)-related pathways.

Multiple Roles of Mitochondria in Aging Processes

Aging is a multifactorial process influenced by genetic factors, nutrition, and lifestyle. According to mitochondrial theory of aging, mitochondrial dysfunction is widely considered a major contributor to age-related processes. Mitochondria are both the main source and targets of detrimental reactions initiated in association with age-dependent deterioration of the cellular functions. Reactions leading to increased reactive oxygen species generation, mtDNA mutations, and oxidation of mitochondrial proteins result in subsequent induction of apoptotic events, impaired oxidative phosphorylation capacity, mitochondrial dynamics, biogenesis and autophagy. This review summarizes the major changes of mitochondria related to aging, with emphasis on mitochondrial DNA mutations, the role of the reactive oxygen species, and structural and functional changes of mitochondria.

Long-term cilostazol administration ameliorates memory decline in senescence-accelerated mouse prone 8 (SAMP8) through a dual effect on cAMP and blood-brain barrier

Phosphodiesterases (PDEs), which hydrolyze and inactivate 3', 5'-cyclic adenosine monophosphate (cAMP) and 3', 5'-cyclic guanosine monophosphate (cGMP), play an important role in synaptic plasticity that underlies memory. Recently, several PDE inhibitors were assessed for their possible therapeutic efficacy in treating cognitive disorders. Here, we examined how cilostazol, a selective PDE3 inhibitor, affects brain functions in senescence-accelerated mouse prone 8 (SAMP8), an animal model of age-related cognitive impairment. Long-term administration of cilostazol restored the impaired context-dependent conditioned fear memory of SAMP8 to match that in normal aging control substrain SAMR1. Cilostazol also increased the number of cells containing phosphorylated cAMP-responsive element binding protein (CREB), a downstream component of the cAMP pathway. Finally, cilostazol improves blood-brain barrier (BBB) integrity, demonstrated by reduced extravasation of 2-deoxy-2-¹⁸F-fluoro-d-glucose and Evans Blue dye in the brains of SAMP8. This improvement in BBB integrity was associated with an increased amount of zona occludens protein 1 (ZO-1) and occludin proteins, components of tight junctions integral to the BBB. The results suggest that long-term administration of cilostazol exerts its beneficial effects on age-related cognitive impairment through a dual mechanism: by enhancing the cAMP system in the brain and by maintaining or improving BBB integrity.

MiR-195 dependent roles of mitofusin2 in the mitochondrial dysfunction of hippocampal neurons in SAMP8 mice

Abnormal gene expression, including mRNAs, and microRNAs (miRNA), have been identified in the development of Alzheimer's disease (AD). Although mitofusin2 (mfn2) has been found to be down-regulated in the neurons from hippocampus and cortex in AD patients, little is known about its roles and the regulatory mechanisms in the pathogenesis of AD. This study was performed to investigate the roles of mfn2 protein and its upstream regulatory mechanism in the progression of AD using a senescence accelerated mouse prone-8 (SAMP8) model. The results of quantitative real-time PCR and western blot revealed that mfn2 expression displayed a consistent decrease with aging in the hippocampus of SAMP8 than did age-matched SAMR1 mice. The luciferase activity assay combined with mutational analysis confirmed the binding site of miR-195 to the 3' -untranslated region (3'-UTR) of mfn2 mRNA. Furthermore, miR-195 inhibitor or antigomir induced the higher level expression of mfn2 protein in vitro and in vivo. In addition, exogenous expression of miR-195 decreased the mitochondrial membrane potential (MMP) of the HT-22 cells by targeting mfn2. In conclusion, these results indicated that deregulation of mfn2 might be involved in mitochondrial dysfunction during the progression of AD, and its decreased expression was regulated at least in part by miR-195 in AD mice. The abnormal expression of miR-195 played a potential role in mitochondrial disorder by targeting mfn2 in hippocampus of SAMP8 mice. Therefore, upregulation of mfn2 protein by inhibiting miR-195 might be a potential new therapeutic strategy for treatment of AD.

Early onset of behavioral alterations in senescence-accelerated mouse prone 8 (SAMP8)

Senescence-accelerated mouse (SAM) is inbred lines of mice originally developed from AKR/J mice. Among the six SAM prone (SAMP) substrains, 8- to 12-month-old SAMP8 have long been used as a model of age-related cognitive impairments. However, little is still known for younger SAMP8 mice. Here, we examined the phenotypical characteristics of 4-month-old SAMP8 using a battery of behavioral tests. Four-month-old SAMP8 mice failed to recognize spatially displaced object in an object recognition task and performed poorly in the probe test of the Morris water maze task compared to SAMR1, suggesting that SAMP8 have impaired spatial memory. In addition, young SAMP8 exhibited enhanced anxiety-like behavior in an open field test and showed depression-like behavior in the forced-swim test. Their circadian rhythm was also disrupted. These abnormal behaviors of young SAMP8 are similar to behavioral alterations also observed in aged mice. In summary, age-related behavioral alterations occur in SAMP8 as young as 4 months old.

EGb761 improves histological and functional recovery in rats with acute spinal cord contusion injury

STUDY DESIGN

This is an experimental study.

OBJECTIVES

The objective of this study was to evaluate the neuroprotective effects of Ginkgo biloba extract 761 (EGb761) on histological features of injured sites and on functional performance of rats subjected to standardized spinal cord injury (SCI).

SETTING

This study was conducted in Xian, Shaanxi, China.

METHODS

Thirty female Sprague-Dawley rats were randomly divided into three groups: sham-operated, saline-treated control and EGb761-treated. The Basso, Beattie, Bresnahan Locomotor Rating Score (BBB score) was calculated and footprint analysis was performed to evaluate the functional performance of the rats in each group. Hematoxylin and eosin (HE) staining and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) and caspase-3 staining were performed to evaluate the necrosis area and apoptotic cells at the injured site in each group.

RESULTS

At 14, but not 1, 3 and 7, days post injury (DPI), rats in the EGb761-treated group exhibited significantly better BBB scores compared with the saline-treated control group (P<0.05). The EGb761-treated group also showed increased stride length, decreased stride width and reduced toe dragging at 14 DPI (P<0.05). Analysis of HE staining revealed that the EGb761-treated group had reduced necrosis at the injury site compared with the saline-treated control group (P<0.05). Analysis of TUNEL and caspase-3 staining demonstrated that cell apoptosis was increased at 1-14 DPI, peaking at 24-h post injury in the gray matter, and 7 DPI in the white matter. At 7 DPI, the quantity of apoptotic cells was significantly decreased in the EGb761-treated group.

CONCLUSION

EGb761 administration during the acute phase after SCI significantly reduced secondary injury-induced tissue necrosis and cell apoptosis and improved functional performance in rats.

Mitochondrial dysfunction: the missing link between aging and sporadic Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disease that represents the most common form of dementia among the elderly. Despite the fact that AD was studied for decades, the underlying mechanisms that trigger this neuropathology remain unresolved. Since the onset of cognitive deficits occurs generally within the 6th decade of life, except in rare familial case, advancing age is the greatest known risk factor for AD. To unravel the pathogenesis of the disease, numerous studies use cellular and animal models based on genetic mutations found in rare early onset familial AD (FAD) cases that represent less than 1 % of AD patients. However, the underlying process that leads to FAD appears to be distinct from that which results in late-onset AD. As a genetic disorder, FAD clearly is a consequence of malfunctioning/mutated genes, while late-onset AD is more likely due to a gradual accumulation of age-related malfunction. Normal aging and AD are both marked by defects in brain metabolism and increased oxidative stress, albeit to varying degrees. Mitochondria are involved in these two phenomena by controlling cellular bioenergetics and redox homeostasis. In the present review, we compare the common features observed in both brain aging and AD, placing mitochondrial in the center of pathological events that separate normal and pathological aging. We emphasize a bioenergetic model for AD including the inverse Warburg hypothesis which postulates that AD is a consequence of mitochondrial deregulation leading to metabolic reprogramming as an initial attempt to maintain neuronal integrity. After the failure of this compensatory mechanism, bioenergetic deficits may lead to neuronal death and dementia. Thus, mitochondrial dysfunction may represent the missing link between aging and sporadic AD, and represent attractive targets against neurodegeneration.

Comparison of Two Old Phytochemicals versus Two Newly Researched Plant-Derived Compounds: Potential for Brain and Other Relevant Ailments

Among hundreds of formulae of Chinese herbal prescriptions and recently extracted active components from the herbs, some of which had demonstrated their functions on nervous system. For the last decade or more, Gingko biloba and Polygala tenuifolia were widely studied for their beneficial effects against damage to the brain. Two compounds extracted from Apium graveolens and Rhizoma coptidis, butylphthalide and berberine, respectively, received much attention recently as potential neuroprotective agents. In this review, the two traditionally used herbs and the two relatively new compounds will be discussed with regard to their potential advantages in alleviating brain and other relevant ailments.

Effects of curcumin (Curcuma longa) on learning and spatial memory as well as cell proliferation and neuroblast differentiation in adult and aged mice by upregulating brain-derived neurotrophic factor and CREB signaling

Aging is a progressive process, and it may lead to the initiation of neurological diseases. In this study, we investigated the effects of wild Indian Curcuma longa using a Morris water maze paradigm on learning and spatial memory in adult and D-galactose-induced aged mice. In addition, the effects on cell proliferation and neuroblast differentiation were assessed by immunohistochemistry for Ki67 and doublecortin (DCX) respectively. The aging model in mice was induced through the subcutaneous administration of D-galactose (100 mg/kg) for 10 weeks. C. longa (300 mg/kg) or its vehicle (physiological saline) was administered orally to adult and D-galactose-treated mice for the last three weeks before sacrifice. The administration of C. longa significantly shortened the escape latency in both adult and D-galactose-induced aged mice and significantly ameliorated D-galactose-induced reduction of cell proliferation and neuroblast differentiation in the subgranular zone of hippocampal dentate gyrus. In addition, the administration of C. longa significantly increased the levels of phosphorylated CREB and brain-derived neurotrophic factor in the subgranular zone of dentate gyrus. These results indicate that C. longa mitigates D-galactose-induced cognitive impairment, associated with decreased cell proliferation and neuroblast differentiation, by activating CREB signaling in the hippocampal dentate gyrus.

Protective effects of Gingko biloba extract 761 on myocardial infarction via improving the viability of implanted mesenchymal stem cells in the rat heart

When introduced into the infarcted heart, bone marrow‑derived mesenchymal stem cells (MSCs) prevent the heart from deleterious remodeling and improve its recovery. The aim of the present study was to investigate the effects of Ginkgo biloba extract (EGb) 761 on the infarcted myocardium microenvironment following MSC transplantation. The established rat myocardial infarction (MI) model, with implanted PKH‑26 marked MSCs (1x105 cells), were randomly divided into two groups: The control group (injected with normal saline) and the EGb 761 treatment group (injected with 100 mg/kg/day EGb 761). The following indices for cardiac function, including the extent of inflammation, oxidative stress, MSC apoptosis and MSC differentiation were measured 1, 2 and 7 days after treatment. The anti‑inflammatory effect of EGb 761 was observed by histological examination. Compared with the respective control group, the malondialdehyde content significantly decreased and the superoxide dismutase, catalase and glutathione peroxidase activity significantly increased in the EGb761‑treated groups. In addition, the apoptotic index gradually decreased (P<0.05) with the extension of MI time in the EGb761-treated groups compared to the respective control groups, suggesting that EGb761 exhbits anti-oxidative effects. In addition, the level of the Fas protein was positively correlated with the implanted MSC apoptotic ratio. Following 7 days of MSC transplantation with EGb 761 treatment, the expression of cTnI in PKH26‑labeled MSCs was observed in the transplanted myocardium. Cardiac function, including the ejection fraction, left ventricular end‑systolic pressure and dp/dtmax significantly increased, and the left ventricular end diastolic diameters, left ventricular end‑diastolic volumes and left ventricular end‑diastolic pressure significantly decreased (P<0.05, vs. the control group). The results demonstrated that EGb 761 is important in improving cardiac function and the infarcted myocardium microenvironment. The present study indicated that the protective effects of EGb 761 on the infarcted myocardium may be mediated by improving the viability and the differentiation of the implanted MSCs into cardiomyocytes.

The behavioral, pathological and therapeutic features of the senescence-accelerated mouse prone 8 strain as an Alzheimer's disease animal model

Alzheimer's disease (AD) is a widespread and devastating progressive neurodegenerative disease. Disease-modifying treatments remain beyond reach, and the etiology of the disease is uncertain. Animal model are essential for identifying disease mechanisms and developing effective therapeutic strategies. Research on AD is currently being carried out in rodent models. The most common transgenic mouse model mimics familial AD, which accounts for a small percentage of cases. The senescence-accelerated mouse prone 8 (SAMP8) strain is a spontaneous animal model of accelerated aging. Many studies indicate that SAMP8 mice harbor the behavioral and histopathological signatures of AD, namely AD-like cognitive and behavioral alterations, neuropathological phenotypes (neuron and dendrite spine loss, spongiosis, gliosis and cholinergic deficits in the forebrain), β-amyloid deposits resembling senile plaques, and aberrant hyperphosphorylation of Tau-like neurofibrillary tangles. SAMP8 mice are useful in the development of novel therapies, and many pharmacological agents and approaches are effective in SAMP8 mice. SAMP8 mice are considered a robust model for exploring the etiopathogenesis of sporadic AD and a plausible experimental model for developing preventative and therapeutic treatments for late-onset/age-related AD, which accounts for the vast majority of cases.

An effective solution to discover synergistic drugs for anti-cerebral ischemia from traditional Chinese medicinal formulae

Recently, the pharmaceutical industry has shifted to pursuing combination therapies that comprise more than one active ingredient. Interestingly, combination therapies have been used for more than 2500 years in traditional Chinese medicine (TCM). Understanding optimal proportions and synergistic mechanisms of multi-component drugs are critical for developing novel strategies to combat complex diseases. A new multi-objective optimization algorithm based on least angle regression-partial least squares was proposed to construct the predictive model to evaluate the synergistic effect of the three components of a novel combination drug Yi-qi-jie-du formula (YJ), which came from clinical TCM prescription for the treatment of encephalopathy. Optimal proportion of the three components, ginsenosides (G), berberine (B) and jasminoidin (J) was determined via particle swarm optimum. Furthermore, the combination mechanisms were interpreted using PLS VIP and principal components analysis. The results showed that YJ had optimal proportion 3(G): 2(B): 0.5(J), and it yielded synergy in the treatment of rats impaired by middle cerebral artery occlusion induced focal cerebral ischemia. YJ with optimal proportion had good pharmacological effects on acute ischemic stroke. The mechanisms study demonstrated that the combination of G, B and J could exhibit the strongest synergistic effect. J might play an indispensable role in the formula, especially when combined with B for the acute stage of stroke. All these data in this study suggested that in the treatment of acute ischemic stroke, besides restoring blood supply and protecting easily damaged cells in the area of the ischemic penumbra as early as possible, we should pay more attention to the removal of the toxic metabolites at the same time. Mathematical system modeling may be an essential tool for the analysis of the complex pharmacological effects of multi-component drug. The powerful mathematical analysis method could greatly improve the efficiency in finding new combination drug from TCM.

Nodes and biological processes identified on the basis of network analysis in the brain of the senescence accelerated mice as an Alzheimer's disease animal model

Harboring the behavioral and histopathological signatures of Alzheimer's disease (AD), senescence accelerated mouse-prone 8 (SAMP8) mice are currently considered a robust model for studying AD. However, the underlying mechanisms, prioritized pathways and genes in SAMP8 mice linked to AD remain unclear. In this study, we provide a biological interpretation of the molecular underpinnings of SAMP8 mice. Our results were derived from differentially expressed genes in the hippocampus and cerebral cortex of SAMP8 mice compared to age-matched SAMR1 mice at 2, 6, and 12 months of age using cDNA microarray analysis. On the basis of PPI, MetaCore and the co-expression network, we constructed a distinct genetic sub-network in the brains of SAMP8 mice. Next, we determined that the regulation of synaptic transmission and apoptosis were disrupted in the brains of SAMP8 mice. We found abnormal gene expression of RAF1, MAPT, PTGS2, CDKN2A, CAMK2A, NTRK2, AGER, ADRBK1, MCM3AP, and STUB1, which may have initiated the dysfunction of biological processes in the brains of SAMP8 mice. Specifically, we found microRNAs, including miR-20a, miR-17, miR-34a, miR-155, miR-18a, miR-22, miR-26a, miR-101, miR-106b, and miR-125b, that might regulate the expression of nodes in the sub-network. Taken together, these results provide new insights into the biological and genetic mechanisms of SAMP8 mice and add an important dimension to our understanding of the neuro-pathogenesis in SAMP8 mice from a systems perspective.

March separate, strike together--role of phosphorylated TAU in mitochondrial dysfunction in Alzheimer's disease

The energy demand and calcium buffering requirements of the brain are met by the high number of mitochondria in neurons and in these, especially at the synapses. Mitochondria are the major producer of reactive oxygen species (ROS); at the same time, they are damaged by ROS that are induced by abnormal protein aggregates that characterize human neurodegenerative diseases such as Alzheimer's disease (AD). Because synaptic mitochondria are long-lived, any damage exerted by these aggregates impacts severely on neuronal function. Here we review how increased TAU, a defining feature of AD and related tauopathies, impairs mitochondrial function by following the principle: 'March separate, strike together!' In the presence of amyloid-β, TAU's toxicity is augmented suggesting synergistic pathomechanisms. In order to restore mitochondrial functions in neurodegeneration as a means of therapeutic intervention it will be important to integrate the various aspects of dysfunction and get a handle on targeting distinct cell types and subcellular compartments.

Antiapoptotic Effects of EGb 761

Ginkgo biloba extracts have long been used in Chinese traditional medicine for hundreds of years. The most significant extract obtained from Ginkgo biloba leaves has been EGb 761, a widely used phytopharmaceutical product in Europe. EGb 761 is a well-defined mixture of active compounds, which contains two main active substances: flavonoid glycosides (24-26%) and terpene lactones (6-8%). These compounds have shown antiapoptotic effects through the protection of mitochondrial membrane integrity, inhibition of mitochondrial cytochrome c release, enhancement of antiapoptotic protein transcription, and reduction of caspase transcription and DNA fragmentation. Other effects include the reduction of oxidative stress (which has been related to the occurrence of vascular, degenerative, and proliferative diseases), coupled to strong induction of phase II-detoxifying and cellular defense enzymes by Nrf2/ARE activation, in addition to the modulation of transcription factors, such as CREB, HIF-1 α , NF- κ B, AP-1, and p53, involved in the apoptosis process. This work reviews experimental results about the antiapoptotic effects induced by the standardized extract of Ginkgo biloba leaves (EGb 761).

EGb761 inhibits inflammatory responses in human chondrocytes and shows chondroprotection in osteoarthritic rat knee

Osteoarthritis (OA) is a degenerative joint disease involving a combination of cartilage degradation and inflammation. EGb761, a standardized extract of Ginkgo biloba leaves, holds an anti-inflammatory potency. Here, we determined whether EGb761 could inhibit lipopolysaccharide (LPS)- and IL-1β-induced inflammatory responses in human articular chondrocytes and apply the chondroprotection in OA rats. We found that LPS markedly induced the productions of PGE2 and NO and the protein expressions of COX-2 and iNOS in human chondrocytes. LPS was also seen to up-regulate the expressions of toll-like receptor-4 (TLR4), its downstream signal TNF receptor-associated factor 6 (TRAF6), and nuclear factor (NF)-κB signaling. These LPS-induced inflammatory responses were efficaciously reversed by EGb761 and its active components quercetin and kampferol. The similar results could be observed by using IL-1β as an in vitro model to mimic an inflammatory response. In an OA rat model, PGE2 and NO levels in blood, the histological alterations, and COX-2 and nitrotyrosine expressions in cartilages were markedly increased, which were effectively reversed by EGb761. Our results suggested that EGb761 exerts the anti-inflammatory effects on human articular chondrocytes and OA rats.

Senescence-Accelerated Mice P8: A Tool to Study Brain Aging and Alzheimer's Disease in a Mouse Model

The causes of aging remain unknown, but they are probably intimately linked to a multifactorial process that affects cell networks to varying degrees. Although a growing number of aging and Alzheimer’s disease (AD) animal models are available, a more comprehensive and physiological mouse model is required. In this context, the senescence-accelerated mouse prone 8 (SAMP8) has a number of advantages, since its rapid physiological senescence means that it has about half the normal lifespan of a rodent. In addition, according to data gathered over the last five years, some of its behavioral traits and histopathology resemble AD human dementia. SAMP8 has remarkable pathological similarities to AD and may prove to be an excellent model for acquiring more in-depth knowledge of the age-related neurodegenerative processes behind brain senescence and AD in particular. We review these facts and particularly the data on parameters related to neurodegeneration. SAMP8 also shows signs of aging in the immune, vascular, and metabolic systems, among others.

By improving regional cortical blood flow, attenuating mitochondrial dysfunction and sequential apoptosis galangin acts as a potential neuroprotective agent after acute ischemic stroke

Ischemic stroke is a devastating disease with a complex pathophysiology. Galangin is a natural flavonoid isolated from the rhizome of Alpina officinarum Hance, which has been widely used as an antioxidant agent. However, its effects against ischemic stroke have not been reported and its related neuroprotective mechanism has not really been explored. In this study, neurological behavior, cerebral infarct volumes and the improvement of the regional cortical blood flow (rCBF) were used to evaluate the therapeutic effect of galangin in rats impaired by middle cerebral artery occlusion (MCAO)-induced focal cerebral ischemia. Furthermore, the determination of mitochondrial function and Western blot of apoptosis-related proteins were performed to interpret the neuroprotective mechanism of galangin. The results showed that galangin alleviated the neurologic impairments, reduced cerebral infarct at 24 h after MCAO and exerted a protective effect on the mitochondria with decreased production of mitochondrial reactive oxygen species (ROS). These effects were consistent with improvements in the membrane potential level (Dym), membrane fluidity, and degree of mitochondrial swelling in a dose-dependent manner. Moreover, galangin significantly improved the reduced rCBF after MCAO. Western blot analysis revealed that galangin also inhibited apoptosis in a dose-dependent manner concomitant with the up-regulation of Bcl-2 expression, down-regulation of Bax expression and the Bax/Bcl-2 ratio, a reduction in cytochrome c release from the mitochondria to the cytosol, the reduced expression of activated caspase-3 and the cleavage of poly(ADP-ribose) polymerase (PARP). All these data in this study demonstrated that galangin might have therapeutic potential for ischemic stroke and play its protective role through the improvement in rCBF, mitochondrial protection and inhibiting caspase-dependent mitochondrial cell death pathway for the first time.

Mitochondrial effects of Ginkgo biloba extract

Oxidative stress and mitochondrial failure promote altered protein degradation, reduced neurotransmission, synapse loss and tau/hyperphosphorylation, which are early stages in the development of Alzheimer's disease (AD). A growing volume of data confirms that Ginkgo biloba extract (GBE) reduces oxidative stress and improves mitochondrial respiration and thus may be useful in preventing or slowing down the progression of AD. Treatment of Caenorhabditis elegans with GBE- extract reduces oxidative stress and extends median lifespan compared with controls. Levels of reactive oxygen species, including the superoxide anion radical, were reduced in brains from GBE-treated mice compared with controls. In older mice, GBE resulted in a protective effect by increasing production of adenosine triphosphate in neurons. A respiratory experiment indicated that GBE was able to rescue Aβ-induced defects in energy metabolism, with results suggesting long-term regulatory effects on mitochondria. GBE also had a selective effect on the activities of mitochondrial enzymes that assemble the electron transport system. The flavonoids, bilobalide and some of the ginkgolides (B and J) had a high protective capacity, indicating that a combination of several compounds within standardized Gingko biloba extracts contribute disproportionately for these protective effects.

Insights into mitochondrial dysfunction: aging, amyloid-β, and tau-A deleterious trio

SIGNIFICANCE

Alzheimer's disease (AD) is an age-related progressive neurodegenerative disorder mainly affecting elderly individuals. The pathology of AD is characterized by amyloid plaques (aggregates of amyloid-β [Aβ]) and neurofibrillary tangles (aggregates of tau), but the mechanisms underlying this dysfunction are still partially unclear.

RECENT ADVANCES

A growing body of evidence supports mitochondrial dysfunction as a prominent and early, chronic oxidative stress-associated event that contributes to synaptic abnormalities and, ultimately, selective neuronal degeneration in AD.

CRITICAL ISSUES

In this review, we discuss on the one hand whether mitochondrial decline observed in brain aging is a determinant event in the onset of AD and on the other hand the close interrelationship of this organelle with Aβ and tau in the pathogenic process underlying AD. Moreover, we summarize evidence from aging and Alzheimer models showing that the harmful trio "aging, Aβ, and tau protein" triggers mitochondrial dysfunction through a number of pathways, such as impairment of oxidative phosphorylation (OXPHOS), elevation of reactive oxygen species production, and interaction with mitochondrial proteins, contributing to the development and progression of the disease.

FUTURE DIRECTIONS

The aging process may weaken the mitochondrial OXPHOS system in a more general way over many years providing a basis for the specific and destructive effects of Aβ and tau. Establishing strategies involving efforts to protect cells at the mitochondrial level by stabilizing or restoring mitochondrial function and energy homeostasis appears to be challenging, but very promising route on the horizon.

Skeletal muscle and beyond: the role of exercise as a mediator of systemic mitochondrial biogenesis

It has been known for more than 4 decades that exercise causes increases in skeletal muscle mitochondrial enzyme content and activity (i.e., mitochondrial biogenesis). Increasing evidence now suggests that exercise can induce mitochondrial biogenesis in a wide range of tissues not normally associated with the metabolic demands of exercise. Perturbations in mitochondrial content and (or) function have been linked to a wide variety of diseases, in multiple tissues, and exercise may serve as a potent approach by which to prevent and (or) treat these pathologies. In this context, the purpose of this review is to highlight the effects of exercise, and the underlying mechanisms therein, on the induction of mitochondrial biogenesis in skeletal muscle, adipose tissue, liver, brain, and kidney.

Ginkgo biloba extract in Alzheimer's disease: from action mechanisms to medical practice

Standardized extract from the leaves of the Ginkgo biloba tree, labeled EGb761, is one of the most popular herbal supplements. Numerous preclinical studies have shown the neuroprotective effects of EGb761 and support the notion that it may be effective in the treatment and prevention of neurodegenerative disorders such as Alzheimer’s disease (AD). Despite the preclinical promise, the clinical efficacy of this drug remains elusive. In this review, possible mechanisms underlying neuroprotective actions of EGb761 are described in detail, together with a brief discussion of the problem of studying this herb clinically to verify its efficacy in the treatment and prevention of AD. Moreover, various parameters e.g., the dosage and the permeability of the blood brain barrier (BBB), impacting the outcome of the clinical effectiveness of the extract are also discussed. Overall, the findings summarized in this review suggest that, a better understanding of the neuroprotective mechanisms of EGb761 may contribute to better understanding of the effectiveness and complexity of this herb and may also be helpful for design of therapeutic strategies in future clinical practice. Therefore, in future clinical studies, different factors that could interfere with the effect of EGb761 should be considered.