Effects of DHA (omega-3 fatty acid) and estradiol on amyloid ß-peptide regulation in the brain.

In the early stages of sporadic Alzheimer's disease (SAD), there is a strong correlation between memory impairment and cortical levels of soluble amyloid-ß peptide oligomers (Aß). It has become clear that Aß disrupt glutamatergic synaptic function, which can in turn lead to the characteristic cognitive deficits of SAD, but the actual pathways are still not well understood. This opinion article describes the pathogenic mechanisms underlying cerebral amyloidosis. These mechanisms are dependent on the amyloid precursor protein and concern the synthesis of Aß peptides with competition between the non-amyloidogenic pathway and the amyloidogenic pathway (i.e. a competition between the ADAM10 and BACE1 enzymes), on the one hand, and the various processes of Aß residue clearance, on the other hand. This clearance mobilizes both endopeptidases (NEP, and IDE) and removal transporters across the blood-brain barrier (LRP1, ABCB1, and RAGE). Lipidated ApoE also plays a major role in all processes. The disturbance of these pathways induces an accumulation of Aß. The description of the mechanisms reveals two key molecules in particular: (i) free estradiol, which has genomic and non-genomic action, and (ii) free DHA as a preferential ligand of PPARα-RXRα and PPARÉ£-RXRα heterodimers. DHA and free estradiol are also self-regulating, and act in synergy. When a certain level of chronic DHA and free estradiol deficiency is reached, a permanent imbalance is established in the central nervous system. The consequences of these deficits are revealed in particular by the presence of Aß peptide deposits, as well as other markers of the etiology of SAD.

[Effect of moxibustion on autophagy in mice with Alzheimer's disease based on mTOR/p70S6K signaling pathway].

OBJECTIVE: To investigate the effect of moxibustion on autophagy and amyloid ß-peptide1-42 (Aß1-42) protein expression in amyloid precursor protein/presenilin 1 (APP/PS1) double-transgenic mice with Alzheimer's disease (AD). METHODS: After 2-month adaptive feeding, fifty-six 6-month-old APP/PS1 double transgenic AD mice were randomly divided into a model group, a moxibustion group, a rapamycin group and an inhibitor group, 14 mice in each group. Another 14 C57BL/6J mice with the same age were used as a normal group. The mice in the moxibustion group were treated with monkshood cake-separated moxibustion at "Baihui"(GV 20), "Fengfu" (GV 16) and "Dazhui" (GV 14) for 20 min; the mice in the rapamycin group were intraperitoneally injected with rapamycin (2 mg/kg); the mice in the inhibitor group were treated with moxibustion and injection of 1.5 mg/kg 3-methyladenine (3-MA). All the treatments were given once a day for consecutive 2 weeks. The morphology of hippocampal tissue was observed by HE staining; the ultrastructure of hippocampal tissue was observed by transmission electron microscopy; the expression of Aß1-42 protein in frontal cortex and hippocampal tissue was detected by immunohistochemistry; the expressions of mammalian target of rapamycin (mTOR), phosphorylated mTOR (p-mTOR), p70 ribosomal protein S6 kinase (p70S6K) and phosphorylated p70S6K (p-p70S6K) protein in hippocampus were detected by Western blot method. RESULTS: Compared with the normal group, the number of neuron cells was decreased, cells were necrotic and deformed, and autophagy vesicle and lysosome were decreased in the model group. Compared with the model group, the number of neuron cells was increased, cell necrosis was decreased, and autophagy vesicle and lysosome were increased in the moxibustion group and the rapamycin group. Compared with the normal group, the protein expressions of Aß1-42, mTOR, p-mTOR, p70S6K and p-p70S6K in the model group were increased (P<0.05); compared with the model group, the protein expressions of Aß1-42, mTOR, p-mTOR, p70S6K and p-p70S6K in the moxibustion group, rapamycin group and inhibitor group were decreased (P<0.05); compared with the inhibitor group, the protein expressions of Aß1-42, mTOR, p-mTOR, p70S6K and p-p70S6K in the moxibustion group and rapamycin group were decreased (P<0.05); compared with the rapamycin group, the protein expressions of mTOR, p-mTOR, p70S6K and p-p70S6K in the moxibustion group were decreased (P<0.05). CONCLUSION: Moxibustion could enhance autophagy in hippocampal tissue of APP/PS1 double transgenic AD mice and reduce abnormal Aß aggregation in brain tissue, the mechanism may be related to the inhibition of mTOR/p70S6K signaling pathway.

Potential therapeutic natural products against Alzheimer's disease with Reference of Acetylcholinesterase.

Alzheimer's disease (AD), is the most common type of dementia primarily affecting the later years of life. Its prevalence is likely to increase in any aging population and will be a major burden on healthcare system by the mid of the century. Despite scientific and technological breakthroughs in the last 50 years, that have expanded our understanding of the disease on a system, cellular and molecular level, therapies that could stop or slow the progression of the disease are still unavailable. The Food and Drug Administration (FDA), has approved acetylcholinesterase (AChE) inhibitors (donepezil, galantamine, tacrine and rivastigmine) and glutamate receptor antagonist (memantine) for the treatment of AD. In this review we summarize the studies reporting phytocompounds and extracts from medicinal plants that show AChE inhibitory activities and could be of potential benefit in AD. Future research directions are suggested and recommendations made to expand the use of medicinal plants and their formulations to prevent, mitigate and treat AD.

Crocin attenuates the granular cells damages on the dentate gyrus and pyramidal neurons in the CA3 regions of the hippocampus and frontal cortex in the rat model of Alzheimer's disease.

Amyloid ß-peptides (Aß) are considered as a major hallmark of Alzheimer's disease (AD) that can induce synaptic loss and apoptosis in brain regions, particularly in the cortex and the hippocampus. Evidence suggests that crocin, as the major component of saffron, can exhibit neuromodulatory effects in AD. However, specific data related to their efficacy to attenuate the synaptic loss and neuronal death in animal models of AD are limited. Hence, we investigated the efficacy of crocin in the CA3 and dentate gyrus (DG) regions of the hippocampus and also in frontal cortex neurons employing a rat model of AD. Male Wistar rats were randomly divided into control, sham, AD model, crocin, and AD model + crocin groups, with 8 rats per group. AD model was established by injecting Aß1-42 into the frontal cortex rats, and thereafter the rats were administrated by crocin (30 mg/kg) for a duration of 12-day. The number of live cells, neuronal arborization and apoptosis were measured using a Cresyl violet, Golgi-Cox and TUNEL staining, respectively. Results showed that, the number of live cells in the hippocampus pyramidal neurons in the CA3 and granular cells in the DG regions of the AD rats significantly decreased, which was significantly rescued by crocin. Compared with the control group, the axonal, spine and dendrites arborization in the frontal cortex and CA3 region of the AD model group significantly decreased. The crocin could significantly reverse this arborization loss in the AD rats (P < 0.05). The apoptotic cell number in the CA3 and DG regions in the AD model group was significantly higher than that of the control group (P < 0.05), while crocin significantly decreased the apoptotic cell number in the AD group (P < 0.05). Conclusion. Crocin can improve the synaptic loss and neuronal death of the AD rats possibly by reducing the neuronal apoptosis.

Inhibition of Aß aggregates in Alzheimer's disease by epigallocatechin and epicatechin-3-gallate from green tea.

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by progressive accumulation of senile plaques, which are primarily composed of misfolded amyloid ß-peptide (Aß). Aß aggregates are believed to be a key factor in the pathogenesis of AD, affecting the nervous system in human body. The therapeutic potential of tea-derived polyphenolic compounds, (-)-epigallocatechin (EGC) and (-)-epicatechin-3-gallate (ECG), for AD was investigated by assessing their effects on the Cu2+/Zn2+-induced or self-assembled Aß40 aggregation using thioflavine T fluorescent spectrometry, inductively coupled plasma mass spectrometry, UV-Vis spectroscopy, transmission electron microscope, silver staining, immunohistochemistry, and immunofluorescence assays. EGC and ECG mildly bind to Cu2+ and Zn2+, and diminish the Cu2+- or Zn2+-induced or self-assembled Aß aggregates; they also modulate the Cu2+/Zn2+-Aß40 induced neurotoxicity on mouse neuroblastoma Neuro-2a cells by reducing the production of ROS. Metal chelating, hydrogen bonding or Van Der Waals force may drive the interaction between the polyphenolic compounds and Aß. The results demonstrate that green tea catechins EGC and ECG are able to alleviate the toxicity of Aß oligomers and fibrils. Particularly, ECG can cross the blood-brain barrier to reduce the Aß plaques in the brain of APP/PS1 mice, thereby protecting neurons from injuries. The results manifest the potential of green tea for preventing or ameliorating the symptoms of AD.

Cognitive improvements and reduction in amyloid plaque deposition by saikosaponin D treatment in a murine model of Alzheimer's disease.

Alzheimer's disease (AD), is a severe neurodegenerative disease that currently lacks an optimally effective therapeutic agent for its management. Saikosaponin D (SSD) is a component extracted from the herb Bupleurum falcatum that is commonly used in Chinese medicine. Although SSD has been reported to exert neuroprotective effects, its pharmacological role in AD has not been previously elucidated. Therefore, the aim of the present study was to investigate whether SSD treatment improves the cognitive function and pathological features of 3xTg mice, a triple-transgenic mouse model of AD that displays classical pathological features of AD. The effects of SSD treatment on the behavioral, histological and physiological features of the animal were quantified. Results from the behavioral experiments on the SSD-treated 3xTg mice identified a significant reduction in memory impairment. In addition, histological staining results indicated that SSD application could preserve the morphology of neurons, reduce apoptosis and significantly inhibit amyloid-ß deposition in the hippocampus of 3xTg mice. SSD treatment also decelerated the activation of microglia and astrocytes in the hippocampus of 3xTg mice, possibly via the inhibition of the NF-κB signal transduction pathway. Therefore, the present study demonstrated the protective effects of SSD against progressive neurodegeneration and identified the potential underlying pharmacological mechanism. It was speculated that SSD may serve as a possible therapeutic agent in AD treatment in the future.

Pine Bark Polyphenolic Extract Attenuates Amyloid-ß and Tau Misfolding in a Model System of Alzheimer's Disease Neuropathology.

Plant-derived polyphenolic compounds possess diverse biological activities, including strong anti-oxidant, anti-inflammatory, anti-microbial, and anti-tumorigenic activities. There is a growing interest in the development of polyphenolic compounds for preventing and treating chronic and degenerative diseases, such as cardiovascular disorders, cancer, and neurological diseases including Alzheimer's disease (AD). Two neuropathological changes of AD are the appearance of neurofibrillary tangles containing tau and extracellular amyloid deposits containing amyloid-ß protein (Aß). Our laboratory and others have found that polyphenolic preparations rich in proanthocyanidins, such as grape seed extract, are capable of attenuating cognitive deterioration and reducing brain neuropathology in animal models of AD. Oligopin is a pine bark extract composed of low molecular weight proanthocyanidins oligomers (LMW-PAOs), including flavan-3-ol units such as catechin (C) and epicatechin (EC). Based on the ability of its various components to confer resilience to the onset of AD, we tested whether oligopin can specifically prevent or attenuate the progression of AD dementia preclinically. We also explored the underlying mechanism(s) through which oligopin may exert its biological activities. Oligopin inhibited oligomer formation of not only Aß1-40 and Aß1-42, but also tau in vitro. Our pharmacokinetics analysis of metabolite accumulation in vivo resulted in the identification of Me-EC-O-ß-Glucuronide, Me-(±)-C-O-ß-glucuronide, EC-O-ß-glucuronide, and (±)-C-O-ß-glucuronide in the plasma of mice. These metabolites are primarily methylated and glucuronidated C and EC conjugates. The studies conducted provide the necessary impetus to design future clinical trials with bioactive oligopin to prevent both prodromal and residual forms of AD.

[Moxibustion at acpoints of governor vessel on regulating PI3K/Akt/mTOR signaling pathway and enhancing autophagy process in APP/PS1 double-transgenic Alzheimer's disease mice].

OBJECTIVE: To observe the eliminating effects of moxibustion at "Baihui" (GV 20), "Fengfu" (GV 16) and "Dazhui" (GV 14) on amyloid ß-peptide (Aß) in brain of the amyloid precursor protein/presenili1 (APP/PS1) double-transgenic mice with Alzheimer's disease (AD) by regulating the phosphoinositide 3-kinases/protein kinase B/mammalian target of rapamycin (PI3K/Akt/mTOR) signaling pathway. METHODS: A total of 60 APP/PS1 double-transgenic mice with AD were randomly divided into a model group, a moxibustion group, a rapamycin group and a combination group (treated with moxibustion and inhibitor), 15 mice in each group, another 15 male C57BL/6J mice with same age and background were selected as the control group. In the moxibustion group, pressing moxibustion was applied at "Baihui" (GV 20) while the mild moxibustion was applied at "Fengfu" (GV 16) and "Dazhui" (GV 14). The treatment was manipulated for 20 min each time, once a day for 2 weeks. In the rapamycin group, rapamycin (2 mg/kg) was given by intraperitoneal injection once a day for 2 weeks. On the basis of the treatment in the moxibustion group, 3-methyladenine (1.5 mg/kg) was given by intraperitoneal injection once a day for 2 weeks. The mice in the control and the model group received normal diet and no intervention was given for 2 weeks. Immunohistochemica method was used to measure the levels of Aß1-42 in the cerebral cortex and hippocampal, transmission electron microscopy was used to observe the formation of autophagosome in hippocampus, and Western blot method was used to observe the levels of PI3K, Akt, p-Akt, mTOR and p-mTOR in hippocampus. RESULTS: Compared with the control group, the levels of Aß1-42 in the cerebral cortex and hippocampal were increased in the model group (P<0.01). Compared with the model group, the levels of Aß1-42 in the cerebral cortex and hippocampal were decreased in the moxibustion group, the rapamycin group and the combination group (all P<0.01), compared with the moxibustion group, the levels of Aß1-42 in the cerebral cortex and hippocampal were increased in the combination group (P<0.01), while there was no significant difference between the moxibustion group and the rapamycin group in the levels of Aß1-42（P>0.05）. Compared with the rapamycin group, the levels of Aß1-42 in the cerebral cortex and hippocampal were increased in the combination group (P<0.01). In the model group, the cytoplasmic utophagic vacuoles and organelles of neuron were reduced. In the moxibustion group, the utophagic vacuoles were increased, and the organelles showed deformation and atrophy. In the rapamycin group, the utophagic vacuoles were widely disturbed and few deformed organelles were found. In the combination group, few utophagic vacuoles were found and additional organelles showed deformation and atrophy. Compared with the control group, the levels of PI3K、Akt、p-Akt、mTOR and p-mTOR were increased in the model group (all P<0.01). Compared with the model group, the levels of PI3K、Akt、p-Akt、mTOR and p-mTOR were reduced in the moxibustion group, the rapamycin group and the combination group (all P<0.01). Compared with the moxibustion group, the levels of PI3K、Akt、and p-mTOR were increased in the rapamycin group and the levels of PI3K、Akt、p-Akt、mTOR and p-mTOR were increased in the combination group (all P<0.01). Compared with the rapamycin group, the levels of PI3K、Akt、p-Akt、mTOR and p-mTOR were increased in the combination group (P<0.01). CONCLUSION: Moxibustion at acupoints of governor vessel can enhance the autophagy process on Aß1-42 in brain of the APP/PS1 double-transgenic AD mice, which may be associated with its effects on inhibiting the abnormal activation of PI3K/Akt/mTOR signaling pathway.

Multi-Target Anti-Alzheimer Activities of Four Prenylated Compounds from Psoralea Fructus.

Alzheimer's disease (AD) is an age-related neurodegenerative disease that is mediated by multiple signaling pathways. In recent years, the components of Psoralea Fructus (PF) have demonstrated some anti-Alzheimer effects both in vitro and in vivo. To further reveal the active compounds of PF and their mechanisms regulating key targets of AD, in this study, we identified four prenylated compounds from the 70% ethanolic aqueous extract of PF, namely bavachin, bavachinin, bavachalcone, and isobavachalcone. Multi-target bioactivity analysis showed that these compounds could differentially inhibit neuroinflammation, oxidative damage, and key AD-related protein targets, such as amyloid ß-peptide 42, ß-secretase, glycogen synthase kinase 3ß, and acetylcholinesterase. These compounds may generate beneficial effects in AD prevention and treatment.

Protection of Differentiating Neuronal Cells from Amyloid ß Peptide-induced Injury by Alkaline Extract of Leaves of Sasa senanensis Rehder.

BACKGROUND/AIM: We have previously reported the protection of doxorubicin-induced keratinocyte toxicity by alkaline extract of the leaves of Sasa senanensis Rehder (SE). In order to extend the generality of the cell protective effect of SE, we investigated whether it also protects rat PC12 and human SH-SY5Y neuron model cells from amyloid ß-peptide (Aß)-induced injury. MATERIALS AND METHODS: Viability of cells was determined by the MTT method. Cytotoxicity was evaluated by the concentration that reduces the cell viability by 50% (CC50). Protection from Aß-induced cytotoxicity was evaluated by the concentration that reversed the Aß-induced reduction of viability by 50% (EC50). The selectivity index (SI) of neuroprotective activity was defined as the ratio of EC50 to CC50 Aß1-42 aggregation was assayed using Aß1-42 ammonium hydroxide. RESULTS: SE showed hormetic growth stimulation at lower concentrations in both neuron precursors and differentiated cells. SE reproducibly inhibited Aß-induced cytotoxicity against both undifferentiated and differentiated neuron cells. Both the extent of differentiation induction and viability depended on the cell density, suggesting the release of growth and differentiation stimulation substances into culture supernatant. Higher concentrations of SE partially reduced the Aß1-42 aggregation. CONCLUSION: Hormetic growth stimulation and inhibition of aggregation may be involved in the neuroprotective activity of SE.

In vitro screening of neuroprotective activity of Indian medicinal plant Withania somnifera.

Canine cognitive dysfunction (CCD) is an age-dependent neurodegenerative condition characterised by changes in decline in learning and memory patterns. The neurodegenerative features of CCD in ageing dogs and cats are similar to human ageing and Alzheimer's disease (AD). Discovering neuroprotective disease-modifying therapies against CCD and AD is a major challenge. Strong evidence supports the role of amyloid ß peptide deposition and oxidative stress in the pathophysiology of CCD and AD. In both the human and canine brain, oxidative damage progressively increases with age. Dietary antioxidants from natural sources hold a great promise in halting the progression of CCD and AD. Withania somnifera (WS), an Ayurvedic tonic medicine, also known as 'Indian ginseng' or ashwagandha has a long history of use in memory-enhancing therapy but there is a dearth of studies on its neuroprotective effects. The objective of this study was to investigate whether WS extract can protect against Aß peptide- and acrolein-induced toxicity. We demonstrated that treatment with WS extract significantly protected the human neuroblastoma cell line SK-N-SH against Aß peptide and acrolein in various cell survival assays. Furthermore, treatment with WS extract significantly reduced the generation of reactive oxygen species in SK-N-SH cells. Finally, our results showed that WS extract is also a potent inhibitor of acetylcholinesterase activity. Thus, our initial findings indicate that WS extract may act as an antioxidant and cholinergic modulator and may have beneficial effects in CCD and AD therapy.

Increasing anti-Aß-induced neurotoxicity ability of Antrodia camphorata-fermented product with deep ocean water supplementary.

BACKGROUND: Antrodia camphorata is proven to probably inhibit the neurotoxicity of amyloid ß-peptide (Aß), known as a risk factor toward the development of Alzheimer's disease. Deep ocean water (DOW), drawn from an ocean depth of more than 200 m, has proven to stimulate the growth and metabolite biosynthesis of fungi owing to its rich minerals and trace elements. Based on these advantages of DOW, this study used statistical response surface methodology (RSM) to investigate the effects of DOW on the growth and anti-Aß-induced neurocytotoxicity ability of A. camphorata. RESULTS: The results showed that DOW was useful for increasing the biomass of A. camphorata and enhancing its neuroprotective capability. The anti-Aß40-induced neurocytotoxicity ability of filtrate was increased via raising the mycelium-secreted components. Furthermore, the anti-Aß40-induced neurocytotoxicity ability of mycelium was also increased by the DOW-stimulated intracellular antioxidants. Using 80% DOW concentration, initial pH 3.3 and 20% inoculum size as the optimal culture conditions of A. camphorata significantly stimulated the biomass and mycelium-mediated Aß40-induced cell viability from 302 ± 14 mg per 100 mL and 49.2 ± 2.2% to 452 ± 33 mg per 100 mL and 65.0 ± 7.4% respectively. CONCLUSION: This study indicated that DOW could be used as a promising supplementary for the production of A. camphorata secondary metabolites with strong antioxidant activity to protect neuron cells from damage based on Aß stimulation cytotoxicity. © 2016 Society of Chemical Industry.

Preferential interaction of the Alzheimer peptide Aß-(1-42) with Omega-3-containing lipid bilayers: structure and interaction studies.

Many age-related neurodegenerative diseases, including Alzheimer Disease (AD), are elicited by an interplay of genetic, environmental, and dietary factors. Food rich in Omega-3 phospholipids seems to reduce the AD incidence. To investigate the molecular basis of this beneficial effect, we have investigated by CD and ESR studies the interaction between the Alzheimer peptide Aß-(1-42) and biomimetic lipid bilayers. The inclusion of 1,2-didocosahexaenoyl-sn-glycero-3-phosphocholine does not change significantly the bilayers organization, but favors its Aß-(1-42) interaction. The Omega-3 lipid amount modulates the effect intensity, suggesting a peptide selectivity for membranes containing polyunsatured fatty acids (PUFA) and providing hints for the mechanism and therapy of AD.

Folic Acid Inhibits Amyloid ß-Peptide Production through Modulating DNA Methyltransferase Activity in N2a-APP Cells.

Alzheimer's disease (AD) is a common neurodegenerative disease resulting in progressive dementia, and is a principal cause of dementia among older adults. Folate acts through one-carbon metabolism to support the methylation of multiple substrates. We hypothesized that folic acid supplementation modulates DNA methyltransferase (DNMT) activity and may alter amyloid ß-peptide (Aß) production in AD. Mouse Neuro-2a cells expressing human APP695 were incubated with folic acid (2.8-40 µmol/L), and with or without zebularine (the DNMT inhibitor). DNMT activity, cell viability, Aß and DNMTs expression were then examined. The results showed that folic acid stimulated DNMT gene and protein expression, and DNMT activity. Furthermore, folic acid decreased Aß protein production, whereas inhibition of DNMT activity by zebularine increased Aß production. The results indicate that folic acid induces methylation potential-dependent DNMT enzymes, thereby attenuating Aß production.

Cytotoxic effects of G(M1) ganglioside and amyloid ß-peptide on mouse embryonic neural stem cells.

AD (Alzheimer's disease) is a neurodegenerative disease and the most common form of dementia. One of the pathological hallmarks of AD is the aggregation of extracellular Aßs (amyloid ß-peptides) in senile plaques in the brain. The process could be initiated by seeding provided by an interaction between G(M1) ganglioside and Aßs. Several reports have documented the bifunctional roles of Aßs in NSCs (neural stem cells), but the precise effects of G(M1) and Aß on NSCs have not yet been clarified. We evaluated the effect of G(M1) and Aß-(1-40) on mouse NECs (neuroepithelial cells), which are known to be rich in NSCs. No change of cell number was detected in NECs cultured in the presence of either G(M1) or Aß-(1-40). On the contrary, a decreased number of NECs were cultured in the presence of a combination of G(M1) and Aß-(1-40). The exogenously added G(M1) and Aß-(1-40) were confirmed to incorporate into NECs. The Ras-MAPK (mitogen-activated protein kinase) pathway, important for cell proliferation, was intact in NECs simultaneously treated with G(M1) and Aß-(1-40), but caspase 3 was activated. NECs treated with G(M1) and Aß-(1-40) were positive in the TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling) assay, an indicator of cell death. It was found that G(M1) and Aß-(1-40) interacted in the presence of cholesterol and sphingomyelin, components of cell surface microdomains. The cytotoxic effect was found also in NSCs prepared via neurospheres. These results indicate that Aß-(1-40) and G(M1) co-operatively exert a cytotoxic effect on NSCs, likely via incorporation into NEC membranes, where they form a complex for the activation of cell death signalling.