Role of pituitary adenylate cyclase-activating polypeptide (PACAP) in the action of ginsenoside Rh2 against beta-amyloid-induced inhibition of rat brain astrocytes

Molecular and Pharmacokinetic Aspects of the Acetylcholinesterase-Inhibitory Potential of the Oleanane-Type Triterpenes and Their Glycosides

The acetylcholinesterase-inhibitory potential of the oleanane-type triterpenes and their glycosides from thebark of Terminalia arjuna (Combreatceae), i.e.,arjunic acid, arjunolic acid, arjungenin, arjunglucoside I, sericic acid and arjunetin, is presented. The studies are based on in silico pharmacokinetic and biomimetic studies, acetylcholinesterase (AChE)-inhibitory activity tests and molecular-docking research. Based on the calculated pharmacokinetic parameters, arjunetin and arjunglucoside I are indicated as able to cross the blood-brain barrier. The compounds of interest exhibit a marked acetylcholinesterase inhibitory potential, which was tested in the TLC bioautography test. The longest time to reach brain equilibrium is observed for both the arjunic and arjunolic acids and the shortest one for arjunetin. All of the compounds exhibit a high and relatively similar magnitude of binding energies, varying from ca. -15 to -13 kcal/mol. The superposition of the most favorable positions of all ligands interacting with AChE is analyzed. The correlation between the experimentally determined IC50 values and the steric parameters of the molecules is investigated. The inhibition of the enzyme by the analyzed compounds shows their potential to be used as cognition-enhancing agents. For the most potent compound (arjunglucoside I; ARG), the kinetics of AChE inhibition were tested. The Michaelis-Menten constant (Km) for the hydrolysis of the acetylthiocholine iodide substrate was calculated to be 0.011 mM.

Neuroprotective Properties of Oleanolic Acid-Computational-Driven Molecular Research Combined with In Vitro and In Vivo Experiments

Oleanolic acid (OA), as a ubiquitous compound in the plant kingdom, is studied for both its neuroprotective and neurotoxic properties. The mechanism of acetylcholinesterase (AChE) inhibitory potential of OA is investigated using molecular dynamic simulations (MD) and docking as well as biomimetic tests. Moreover, the in vitro SH-SY5Y human neuroblastoma cells and the in vivo zebrafish model were used. The inhibitory potential towards the AChE enzyme is examined using the TLC-bioautography assay (the IC50 value is 9.22 μM). The CH-π interactions between the central fragment of the ligand molecule and the aromatic cluster created by the His440, Phe288, Phe290, Phe330, Phe331, Tyr121, Tyr334, Trp84, and Trp279 side chains are observed. The results of the in vitro tests using the SH-SY5Y cells indicate that the viability rate is reduced to 71.5%, 61%, and 43% at the concentrations of 100 µg/mL, 300 µg/mL, and 1000 µg/mL, respectively, after 48 h of incubation, whereas cytotoxicity against the tested cell line with the IC50 value is 714.32 ± 32.40 µg/mL. The in vivo tests on the zebrafish prove that there is no difference between the control and experimental groups regarding the mortality rate and morphology (p > 0.05).

American Ginseng for the Treatment of Alzheimer's Disease: A Review

Alzheimer's disease (AD) is a prevalent degenerative condition that is increasingly affecting populations globally. American ginseng (AG) has anti-AD bioactivity, and ginsenosides, as the main active components of AG, have shown strong anti-AD effects in both in vitro and in vivo studies. It has been reported that ginsenosides can inhibit amyloid β-protein (Aβ) production and deposition, tau phosphorylation, apoptosis and cytotoxicity, as well as possess anti-oxidant and anti-inflammatory properties, thus suppressing the progression of AD. In this review, we aim to provide a comprehensive overview of the pathogenesis of AD, the potential anti-AD effects of ginsenosides found in AG, and the underlying molecular mechanisms associated with these effects. Additionally, we will discuss the potential use of AG in the treatment of AD, and how ginsenosides in AG may exert more potent anti-AD effects in vivo may be a direction for further research.

Role of ginseng in the neurovascular unit of neuroinflammatory diseases focused on the blood-brain barrier

Ginseng has long been considered as an herbal medicine. Recent data suggest that ginseng has anti-inflammatory properties and can improve learning- and memory-related function in the central nervous system (CNS) following the development of CNS neuroinflammatory diseases such as Alzheimer's disease, cerebral ischemia, and other neurological disorders. In this review, we discuss the role of ginseng in the neurovascular unit, which is composed of endothelial cells surrounded by astrocytes, pericytes, microglia, neural stem cells, oligodendrocytes, and neurons, especially their blood-brain barrier maintenance, anti-inflammatory effects and regenerative functions. In addition, cell-cell communication enhanced by ginseng may be attributed to regeneration via induction of neurogenesis and angiogenesis in CNS diseases. Thus, ginseng may have therapeutic potential to exert cognitive improvement in neuroinflammatory diseases such as stroke, traumatic brain injury, multiple sclerosis, Parkinson's disease, and Alzheimer's disease.

Transcriptomic Insights into the Response of the Olfactory Bulb to Selenium Treatment in a Mouse Model of Alzheimer's Disease

Alzheimer’s disease (AD) is a devastating neurodegenerative disorder characterized by the presence of extracellular senile plaques primarily composed of Aβ peptides and intracellular neurofibrillary tangles (NFTs) composed of hyperphosphorylated tau proteins. Olfactory dysfunction is an early clinical phenotype in AD and was reported to be attributable to the presence of NFTs, senile Aβ plaques in the olfactory bulb (OB). Our previous research found that selenomethionine (Se-Met), a major form of selenium (Se) in organisms, effectively increased oxidation resistance as well as reduced the generation and deposition of Aβ and tau hyperphosphorylation in the olfactory bulb of a triple transgenic mouse model of AD (3×Tg-AD), thereby suggesting a potential therapeutic option for AD. In this study, we further investigated changes in the transcriptome data of olfactory bulb tissues of 7-month-old triple transgenic AD (3×Tg-AD) mice treated with Se-Met (6 µg/mL) for three months. Comparison of the gene expression profile between Se-Met-treated and control mice revealed 143 differentially expressed genes (DEGs). Among these genes, 21 DEGs were upregulated and 122 downregulated. The DEGs were then annotated against the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases. The results show that upregulated genes can be roughly classified into three types. Some of them mainly regulate the regeneration of nerves, such as Fabp7, Evt5 and Gal; some are involved in improving cognition and memory, such as Areg; and some are involved in anti-oxidative stress and anti-apoptosis, such as Adcyap1 and Scg2. The downregulated genes are mainly associated with inflammation and apoptosis, such as Lrg1, Scgb3a1 and Pglyrp1. The reliability of the transcriptomic data was validated by quantitative real time polymerase chain reaction (qRT-PCR) for the selected genes. These results were in line with our previous study, which indicated therapeutic effects of Se-Met on AD mice, providing a theoretical basis for further study of the treatment of AD by Se-Met.

Acute and genetic toxicity of GS-E3D, a new pectin lyase-modified red ginseng extract

Korean red ginseng and its extract have been used as traditional medicines and functional foods in countries worldwide. Pectin lyase-modified red ginseng extract (GS-E3D) was newly developed as a dietary supplement for obesity, diabetes-related renal dysfunction, etc. In this study, the safety of GS-E3D on acute toxicity and genotoxicity was evaluated. For acute study, Sprague-Dawley rats were administrated by oral gavage at a dose of 5000 mg/kg GS-E3D. To evaluate genotoxicity of GS-E3D, we conducted three-battery tests, which are Ames test using Escherichia coli (WP2uvrA pKM101) and Salmonella typhimurium strains (TA98, TA100, TA1535 and TA1537), chromosomal aberration test -using Chinese hamster lung cells, and micronucleus test using ICR mice. In acute toxicity studies, there were no dead animals or abnormal necropsy findings in the control group and GS-E3D (5000 mg/kg) treated group. GS-E3D did not induce mutagenicity in the bacterial test, chromosomal aberrations in Chinese hamster lung cells and micronuclei in bone marrow cells of mice. Conclusively, the approximate lethal dose of GS-E3D was greater than 5000 mg/kg bw and GS-E3D has no genotoxic potential in the three-battery tests on genotoxicity.

Neuropeptides Exert Neuroprotective Effects in Alzheimer's Disease

Alzheimer's disease (AD) is an age-related neurodegenerative disorder characterized by cognitive deficits and neuronal loss. Deposition of beta-amyloid peptide (Aβ) causes neurotoxicity through the formation of plaques in brains of Alzheimer's disease. Numerous studies have indicated that the neuropeptides including ghrelin, neurotensin, pituitary adenylate cyclase-activating polypeptide (PACAP), neuropeptide Y, substance P and orexin are closely related to the pathophysiology of Alzheimer's disease. The levels of neuropeptides and their receptors change in Alzheimer's disease. These neuropeptides exert neuroprotective roles mainly through preventing Aβ accumulation, increasing neuronal glucose transport, increasing the production of neurotrophins, inhibiting endoplasmic reticulum stress and autophagy, modulating potassium channel activity and hippocampal long-term potentiation. Therefore, the neuropeptides may function as potential drug targets in the prevention and cure of Alzheimer's disease.

Gut microbiota-mediated pharmacokinetics of ginseng saponins

Orally administered ginsengs come in contact with the gut microbiota, and their hydrophilic constituents, such as ginsenosides, are metabolized to hydrophobic compounds by gastric juice and gut microbiota: protopanxadiol-type ginsenosides are mainly transformed into compound K and ginsenoside Rh2; protopanaxatriol-type ginsenosides to ginsenoside Rh1 and protopanaxatriol, and ocotillol-type ginsenosides to ocotillol. Although this metabolizing activity varies between individuals, the metabolism of ginsenosides to compound K by gut microbiota in individuals treated with ginseng is proportional to the area under the blood concentration curve for compound K in their blood samples. These metabolites such as compound K exhibit potent pharmacological effects, such as antitumor, anti-inflammatory, antidiabetic, antiallergic, and neuroprotective effects compared with the parent ginsenosides, such as Rb1, Rb2, and Re. Therefore, to monitor the potent pharmacological effects of ginseng, a novel probiotic fermentation technology has been developed to produce absorbable and bioactive metabolites. Based on these findings, it is concluded that gut microbiota play an important role in the pharmacological action of orally administered ginseng, and probiotics that can replace gut microbiota can be used in the development of beneficial and bioactive ginsengs.

Ginsenoside Rh2 reverses sleep deprivation-induced cognitive deficit in mice

Sleep deprivation (SD) negatively caused cognitive deficit, which was associated with oxidative stress induced damage. Ginsenoside Rh2 had the ability to protect against damage caused by reactive oxygen species in vitro, showing antioxidant property. Therefore, it was hypothesized that Ginsenoside Rh2 could prevent SD-induced cognitive deficit via its antioxidant properties. In this study, the effect of Ginsenoside Rh2 on memory impairment induced by sleep deprivation was investigated. The mice were sleep deprived continuously for 14 days using our self-made Sleep Interruption Apparatus (SIA). Ginsenoside Rh2 was administered intraperitoneally at two doses (20 and 40 μmol/kg) for 20 days. Thereafter, behavioral studies were conducted to test the learning and memory ability using object location recognition (OLR) experiment and passive avoidance (PA) test. Additionally, the oxidative stress parameters in the serum and the brain tissues (cortex and hippocampus) were assessed, including the superoxide dismutase (SOD) enzyme activity, the total antioxidant reactivity (TAR), the malondialdehyde (MDA) level, the glutathione (GSH) level, and the lipid peroxidation (LPO) content. The results revealed that SD impaired both spatial and non-spatial memory (P < 0.05). Treatment with Ginsenoside Rh2 at both doses prevented memory impairment induced by SD. Moreover, Ginsenoside Rh2 normalized the reduction of SOD and TAR activities in the serum (P < 0.01) and the decrease of GSH content in both the cortex and hippocampus (P < 0.05) induced by SD. Furthermore, Ginsenoside Rh2 significantly decreased the MDA level in the serum (P < 0.05) and the LPO content in both the cortex and hippocampus (P < 0.05) compared to SD group. In conclusion, sleep deprivation impaired both spatial and non-spatial memory and Ginsenoside Rh2 reversed this impairment, probably by preventing the oxidative stress damage in the body, including the serum and brain during sleep deprivation.

TCM, brain function and drug space

Covering: up to 2015. Traditional Chinese medicine has played a significant role in the mainstream healthcare system in China for thousands of years. Here, we summarize 84 major compounds from 15 selected herbal medicines targeting neurodegenerative diseases. We present a perspective based on the analysis of physicochemical properties of these TCM compounds, and comparison with current drugs and candidates for the treatment of Parkinson's and Alzheimer's disease. The results demonstrate that traditional Chinese medicines contain compounds possessing physicochemical properties that have excellent overlap with developed western medicines.

Anti-Inflammatory Effects of Ginsenoside-Rh2 Inhibits LPS-Induced Activation of Microglia and Overproduction of Inflammatory Mediators Via Modulation of TGF-β1/Smad Pathway

Microglia activation plays an important role in neuroinflammation and contributes to several neurological disorders. Hence, inhibition of both microglia activation and pro-inflammatory cytokines may lead to the effective treatment of neurodegenerative diseases. In this study, we found that GRh2 inhibited the inflammatory response to lipopolysaccharide (LPS) and prevented the LPS-induced neurotoxicity in microglia cells. GRh2 significantly decreased the generation of nitric oxide production, and tumor necrosis factor-α, interleukin (IL)-6, IL-1β, cyclooxygenase-2 and inducible nitric oxide synthase in LPS-induced activated microglia cells. Furthermore, GRh2 (20 and 50 μM) significantly increased TGF-β1 expression and reduced the expression of Smad. These results suggest that GRh2 effectively inhibits microglia activation and production of pro-inflammatory cytokines via modulating the TGF-β1/Smad pathway.

Effects of pectin lyase-modified red ginseng extracts in high-fat diet-fed obese mice

Red ginseng and its extracts have been used as traditional medicines and functional foods in countries worldwide. The aim of this study was to examine the bioavailability of pectin lyase-modified red ginseng extracts (GS-E3D), and the effects of GS-E3D on adipogenesis of 3T3-L1 adipocytes, as well as on metabolic disorders such as hyperglycemia, dyslipidemia, and fatty liver in high-fat diet fed obese C57BL/6 mice. Mice were divided into 5 groups: normal diet group, high fat diet-vehicle group, high fat diet + 0.1 g/kg GS-E3D (0.1-GS-E3D), high fat diet + 0.3 g/kg (0.3-GS-E3D), high fat diet + 1.0 g/kg (1.0-GS-E3D). Treatment of GS-E3D reduced differentiation of 3T3-L1 adipocytes with low cytotoxicity. In the animal model, compared to the high fat diet control, serum glucose, total cholesterol, LDL-cholesterol, HDL-cholesterol, TG, and leptin level were reduced in treatment animals in a dose-dependent manner. In addition, we found that GS-E3D could decrease total hepatic lipid droplets. These results suggest that GS-E3D, as a dietary supplement, has beneficial effects on obesity and may have useful effects in health-care products.

Neuroprotection by saponins

Saponins, an important group of bioactive plant natural products, are glycosides of triterpenoid or steroidal aglycones. Their diverse biological activities are ascribed to their different structures. Saponins have long been recognized as key ingredients in traditional Chinese medicine. Accumulated evidence suggests that saponins have significant neuroprotective effects on attenuation of central nervous system disorders, such as stroke, Alzheimer's disease, Parkinson's disease, and Huntington's disease. However, our understanding of the mechanisms underlying the observed effects remains incomplete. Based on recently reported data from basic and clinical studies, this review highlights the proposed mechanisms of their neuroprotective function including antioxidant, modulation of neurotransmitters, anti-apoptosis, anti-inflammation, attenuating Ca(2+) influx, modulating neurotrophic factors, inhibiting tau phosphorylation, and regeneration of neural networks.

Pregnenolone, a cholesterol metabolite, induces glioma cell apoptosis via activating extrinsic and intrinsic apoptotic pathways

Gliomas are one of the most common types of malignant tumors worldwide, however, an effective therapeutic strategy not yet been fully determined. The present study aimed to investigate the anti-glioma activity and underlying mechanisms of pregnenolone, which originates from cholesterol and is metabolized into important steroid hormones in the body. The results demonstrated that 100 μM pregnenolone induced a significant loss of cell viability in various malignant glioma cell lines. In the U-87 MG, LN-18 and C6 cell lines, the loss of cell viability resulted from cell apoptosis, which was evidenced by apoptotic nuclear morphology changes and caspase 3 activation. Moreover, the increased activities of caspase 8 and 9 strongly indicated that pregnenolone activated the extrinsic and intrinsic pathways of apoptosis. Additionally, glioma cell apoptosis was prevented by the general caspase inhibitor, Z-VAD-FMK. In the C6 cells, upregulation of Fas and Fas ligand triggered the activation of the extrinsic pathway, whereas knockdown of Fas significantly abrogated the cell apoptosis that was induced by pregnenolone. Furthermore, downregulation of the anti-apoptotic protein, B-cell lymphoma 2 and upregulation of pro-apoptotic proteins, such as Bax and Bak, activated the intrinsic pathway. In conclusion, pregnenolone induced glioma cell apoptosis in a caspase-dependent manner, which was mediated by activation of the extrinsic and intrinsic apoptotic pathways.

Pituitary adenylate cyclase-activating polypeptide protects against β-amyloid toxicity

Pituitary adenylate cyclase activating polypeptide (PACAP) is a neurotrophin. However, its role in human Alzheimer's disease (AD) is largely unknown. We examined PACAP expression in postmortem human AD and triple transgenic mouse (3xTG, Psen1/APPSwe/TauP301L) brains. We established an in vitro model of primary neuronal cell culture to study the protective effects of PACAP against β-amyloid (Aβ) toxicity. We further studied the PACAP-Sirtuin 3 (Sirt3) pathway on mitochondrial function. PACAP expression was reduced in AD and 3xTG mouse brains. This reduction was inversely correlated with Aβ and tau protein levels. Treatment with PACAP effectively protected neurons against Aβ toxicity. PACAP stimulated mitochondrial Sirt3 production. Similar to PACAP, Sirt3 was reduced in AD and 3xTG brains. Knocking down Sirt3 compromised the neuroprotective effects of PACAP, and this was reversed by over-expressing Sirt3. PACAP is reduced in AD and may represent a novel therapeutic strategy.

Ginsenoside Rh2 improves learning and memory in mice

A wide range of plant foods and dietary supplements are able to modify the functioning of the central nervous system. In the present study, we observed that oral administration of ginsenoside Rh2 (10 mg/mL) for 3 weeks significantly improved spatial learning and memory. Spatial memory and learning was evaluated in mice by hippocampus-dependent tasks (Morris water maze test) and immunohistochemical marker of cell genesis bromodeoxyuridine. Ginsenoside Rh2 treatment (30 days) promoted cell survival and genesis. Further, ginsenoside Rh2 treatment in enriched condition had no significant effects on cell survival compared with standard condition exposure. These results revealed that ginsenoside Rh2-mediated spatial learning and memory improvement was associated with cell genesis and survival and may be parallel to the mechanism of environmental enrichment. Therefore, ginsenoside Rh2 may have efficacy as a dietary supplement for spatial learning and memory improvement.

Antistress effect of red ginseng in brain cells is mediated by TACE repression via PADI4

Ginseng is known to have antistress effects. Previously, red ginseng (RG) was shown to repress stress-induced peptidyl arginine deiminase type IV (PADI4) via estrogen receptor β (ERβ) in the brain, thus inhibiting brain cell apoptosis. Moreover, tumor necrosis factor (TNF)-α plays a critical role in immobilization (IMO) stress. However, the signaling pathway of RG-mediated repressesion of inflammation is not completely understood. In this study, we determined how RG modulated gene expression in stressed brain cells. Since secretion of TNF-α is modulated via TNF-α converting enzyme (TACE) and nuclear factor (NF)-κB, we examined the inflammatory pathway in stressed brain cells. Immunohistochemistry revealed that TACE was induced by IMO stress, but RG repressed TACE induction. Moreover, PADI4 siRNA repressed TACE expression compared to the mock transfected control suggesting that PADI4 was required for TACE expression. A reporter assay also revealed that H2O2 oxidative stress induced NF-κB in neuroblastoma SK-N-SH cells, however, RG pretreatment repressed NF-κB induction. These findings were supported by significant induction of nitric oxide and reactive oxygen species (ROS) by oxidative stress, which could be repressed by RG administration. Taken together, RG appeared to repress stress-induced PADI4 via TACE and NF-κB in brain cells thus preventing production of ROS and subsequently protecting brain cells from apoptosis.

Effects of Panax ginseng in Neurodegenerative Diseases

Ginseng, the root of the Panax ginseng, has been a popular and widely-used traditional herbal medicine in Korea, China, and Japan for thousands of years. Now it has become popular as a functional health food and is used globally as a natural medicine. Evidence is accumulating in the literature on the physiological and pharmacological effects of P. ginseng on neurodegenerative diseases. Possible ginseng- or ginsenosides-mediated neuroprotective mechanisms mainly involve maintaining homeostasis, and anti-inflammatory, anti-oxidant, anti-apoptotic, and immune-stimulatory activities. This review considers publications dealing with the various actions of P. ginseng that are indicative of possible neurotherapeutic efficacies in neurodegenerative diseases and neurological disorders such as Parkinson’s disease, Alzheimer’s disease, Huntington’s disease, and amyotrophic lateral sclerosis and multiple sclerosis.

A comprehensive review of the therapeutic and pharmacological effects of ginseng and ginsenosides in central nervous system

Ginseng is one of the most widely used herbal medicines in human. Central nervous system (CNS) diseases are most widely investigated diseases among all others in respect to the ginseng’s therapeutic effects. These include Alzheimer’s disease, Parkinson’s disease, cerebral ischemia, depression, and many other neurological disorders including neurodevelopmental disorders. Not only the various types of diseases but also the diverse array of target pathways or molecules ginseng exerts its effect on. These range, for example, from neuroprotection to the regulation of synaptic plasticity and from regulation of neuroinflammatory processes to the regulation of neurotransmitter release, too many to mention. In general, ginseng and even a single compound of ginsenoside produce its effects on multiple sites of action, which make it an ideal candidate to develop multi-target drugs. This is most important in CNS diseases where multiple of etiological and pathological targets working together to regulate the final pathophysiology of diseases. In this review, we tried to provide comprehensive information on the pharmacological and therapeutic effects of ginseng and ginsenosides on neurodegenerative and other neurological diseases. Side by side comparison of the therapeutic effects in various neurological disorders may widen our understanding of the therapeutic potential of ginseng in CNS diseases and the possibility to develop not only symptomatic drugs but also disease modifying reagents based on ginseng.

Pituitary adenylate cyclase-activating polypeptide protects astroglial cells against oxidative stress-induced apoptosis

Oxidative stress, associated with a variety of disorders including neurodegenerative diseases, results from accumulation of reactive oxygen species (ROS). Oxidative stress is not only responsible for neuron apoptosis, but can also provoke astroglial cell death. Numerous studies indicate that pituitary adenylate cyclase-activating polypeptide (PACAP) promotes neuron survival, but nothing is known regarding the action of PACAP on astroglial cell survival. Thus, the purpose of the present study was to investigate the potential glioprotective effect of PACAP on H(2)O(2)-induced astrocyte death. Pre-treatment of cultured rat astrocytes with nanomolar concentrations of PACAP prevented cell death provoked by H(2)O(2) (300 μM), whereas vasoactive intestinal polypeptide was devoid of protective activity. The effect of PACAP on astroglial cell survival was abolished by the type 1 PACAP receptor antagonist, PACAP6-38. The protective action of PACAP was blocked by the protein kinase A inhibitor H89, the protein kinase C inhibitor chelerythrine and the mitogen-activated protein (MAP)-kinase kinase (MEK) inhibitor U0126. PACAP stimulated glutathione formation, and blocked H(2)O(2)-evoked ROS accumulation and glutathione content reduction. In addition, PACAP prevented the decrease of mitochondrial activity and caspase 3 activation induced by H(2)O(2). Taken together, these data indicate for the first time that PACAP, acting through type 1 PACAP receptor, exerts a potent protective effect against oxidative stress-induced astrocyte death. The anti-apoptotic activity of PACAP on astrocytes is mediated through the protein kinase A, protein kinase C and MAPK transduction pathways, and can be accounted for by inhibition of ROS-induced mitochondrial dysfunctions and caspase 3 activation.

Ginsenosides and their CNS targets

Ginsenosides are a special group of triterpenoid saponins attributed to medical effects of ginseng. Therefore, they have been research targets over the last three decades to explain ginseng actions and a wealth of literature has been presented reporting on ginsenosides' effects on the human body. Recently, there is increasing evidence on beneficial effects of ginsenosides to the central nervous system (CNS). Using a wide range of in vitro and in vivo models, researchers have attributed these effects to specific pharmacological actions of ginsenosides on cerebral metabolism, oxidative stress and radical formation, neurotransmitter imbalance and membrane stabilizing effects, and even antiapoptotic effects. Modulating these particular mechanisms by ginsenosides has thus been reported to exert either general stimulatory effects on the brain functions or protecting the CNS against various disease conditions. In this review, we try to address the recently reported ginsenosides' actions on different CNS targets particularly those supporting possible therapeutic efficacies in CNS disorders and neurodegenerative diseases.

Ginseng for cognition

BACKGROUND

Ginseng is a herbal medicine in widespread use throughout the world. Its effect on the brain and nervous system has been investigated. It has been suggested, on the basis of both laboratory and clinical studies, that it may have beneficial effects on cognitive performance.

OBJECTIVES

To evaluate the efficacy and adverse effects of ginseng given to improve cognitive performance in healthy participants, participants with cognitive impairment or dementia.To highlight the quality and quantity of research evidence available.

SEARCH STRATEGY

The Specialized Register of the Cochrane Dementia and Cognitive Improvement Group (CDCIG), The Cochrane Library, MEDLINE, EMBASE, PsycINFO, CINAHL, LILACS, clinical trials registries and grey literature sources were searched on 24 February 2009 using the following terms: ginseng* OR panax OR ginsan OR "Jen Shen"OR shinseng OR Renshen OR schinseng OR ninjin OR gingilone OR panaxoside* OR ginsenoside* OR protopanaxa* OR protopanaxadiol OR protopanaxatriol OR panaxagin OR ginsenol OR ginsenine and terms for dementia and cognition. The CDCIG Specialized Register contains records from all major health care databases (The Cochrane Library, MEDLINE, EMBASE, PsycINFO, CINAHL, LILACS) as well as from many clinical trials registries and grey literature sources.

SELECTION CRITERIA

All double-blind and single-blind randomized, placebo controlled trials assessing the effects of ginseng on cognitive function were eligible for inclusion. Interventions were considered to be ginseng if they were compounds containing ginseng or active agents of the Panax genus as the major component.

DATA COLLECTION AND ANALYSIS

Characteristics of each included trial were extracted independently by two reviewers using a self-developed data extraction form and entered into RevMan 5.0 software. Authors of identified trials were contacted for additional information and unpublished data. The effects of ginseng in healthy participants, participants with cognitive impairment or dementia were addressed independently.

MAIN RESULTS

Nine randomized, double-blind, placebo controlled trials meeting the inclusion criteria were identified. Eight trials enrolled healthy participants, and one was of subjects with age-associated memory impairment (AAMI).Only five of the identified trials had extractable information and were included in the analysis. Four studies investigated the effects of ginseng extract and one assessed the efficacy of ginseng compound HT008-1. All of these trials investigated the effects of ginseng on healthy participants. Pooling the data was impossible owing to heterogeneity in outcome measures, trial duration, and ginseng dosage. Results of the analysis suggested improvement of some aspects of cognitive function, behavior and quality of life. No serious adverse events associated with ginseng were found.

AUTHORS' CONCLUSIONS

Currently, there is a lack of convincing evidence to show a cognitive enhancing effect of Panax ginseng in healthy participants and no high quality evidence about its efficacy in patients with dementia. Randomized, double-blind, placebo-controlled, parallel group trials with large sample sizes are needed to further investigate the effect of ginseng on cognition in different populations, including dementia patients.

Anti-aging herbal medicine--how and why can they be used in aging-associated neurodegenerative diseases?

Aging is a universal biological process that leads to progressive and deleterious changes in organisms. From ancient time, mankind has already interested in preventing and keeping ourselves young. Anti-aging study is certainly not a new research area. Nowadays, the meaning of anti-aging has been changed from simply prolonging lifespan to increasing health span, which emphasizes more on the quality of life. This is the concept of healthy aging and prevention of pathological aging, which is associated with diseases. Keeping our brain functions as in young age is an important task for neuroscientists to prevent aging-associated neurological disorders, such as Alzheimer's diseases (AD) and Parkinson's disease (PD). The causes of these diseases are not fully understood, but it is believed that these diseases are affected by multiple factors. Neurodegenerative diseases can be cross-linked with a number of aging-associated conditions. Based on this, a holistic approach in anti-aging research seems to be more reasonable. Herbal medicine has a long history in Asian countries. It is believed that many of the medicinal herbs have anti-aging properties. Recent studies have shown that some medicinal herbs are effective in intervention or prevention of aging-associated neurological disorders. In this review, we use wolfberry and ginseng as examples to elaborate the properties of anti-aging herbs. The characteristics of medicinal herbs, especially their applications in different disease stages (prevention and intervention) and multi-targets properties, allow them to be potential anti-aging intervention in prevention and treatment of the aging-associated neurological disorders.

Neuroprotective herbs and foods from different traditional medicines and diets

Plant secondary metabolites include an array of bioactive constituents form both medicinal and food plants able to improve human health. The exposure to these phytochemicals, including phenylpropanoids, isoprenoids and alkaloids, through correct dietary habits, may promote health benefits, protecting against the chronic degenerative disorders mainly seen in Western industrialized countries, such as cancer, cardiovascular and neurodegenerative diseases. In this review, we briefly deal with some plant foods and herbs of traditional medicines and diets, focusing on their neuroprotective active components. Because oxidative stress and neuroinflammation resulting from neuroglial activation, at the level of neurons, microglial cells and astrocytes, are key factors in the etiopathogenesis of both neurodegenerative and neurological diseases, emphasis will be placed on the antioxidant and anti-inflammatory activity exerted by specific molecules present in food plants or in remedies prescribed by herbal medicines.

Effect of wild ginseng on scopolamine-induced acetylcholine depletion in the rat hippocampus

Objectives

The ameliorating effects of wild ginseng on learning and memory deficits were investigated in rats.

Methods

Rats were treated daily with wild ginseng or cultivated ginseng for 7 days at 30 min before scopolamine injection (2 mg/kg, i.p.). After inducing cognitive impairment by the administration of scopolamine, behavioural assessment using the Morris water maze was performed. Changes in cholinergic system reactivity were also examined by measuring the immunoreactive neurons of choline acetyltransferase and the reactivity of acetylcholinesterase in the hippocampus.

Key findings

Scopolamine injection induced impaired performance in the water maze test and severe cell losses in hippocampal cholinergic neurons, as indicated by decreased choline acetyltransferase immunoreactivity and increased acetylcholinesterase reactivity. Daily administration of wild ginseng produced a significant improvement in the escape latency for finding the platform in the Morris water maze and reduced the loss of cholinergic immunoreactivity in the hippocampus. The reduced expression of brain-derived neurotrophic factor mRNA due to the scopolamine injection was recovered to normal levels by the administration of wild ginseng.

Conclusions

Wild ginseng demonstrates a significant neuroprotective effect against scopolamine-induced neuronal and cognitive impairment.

Ginsenoside Rh2 induces ligand-independent Fas activation via lipid raft disruption

Lipid rafts are plasma membrane platforms mediating signal transduction pathways for cellular proliferation, differentiation and apoptosis. Here, we show that membrane fluidity was increased in HeLa cells following treatment with ginsenoside Rh2 (Rh2), as determined by cell staining with carboxy-laurdan (C-laurdan), a two-photon dye designed for measuring membrane hydrophobicity. In the presence of Rh2, caveolin-1 appeared in non-raft fractions after sucrose gradient ultracentrifugation. In addition, caveolin-1 and GM1, lipid raft landmarkers, were internalized within cells after exposure to Rh2, indicating that Rh2 might disrupt lipid rafts. Since cholesterol overloading, which fortifies lipid rafts, prevented an increase in Rh2-induced membrane fluidity, caveolin-1 internalization and apoptosis, lipid rafts appear to be essential for Rh2-induced apoptosis. Moreover, Rh2-induced Fas oligomerization was abolished following cholesterol overloading, and Rh2-induced apoptosis was inhibited following treatment with siRNA for Fas. This result suggests that Rh2 is a novel lipid raft disruptor leading to Fas oligomerization and apoptosis.