Therapeutic efficacy of stemazole in a beta-amyloid injection rat model of Alzheimer's disease

Stemazole Promotes Oligodendrocyte Precursor Cell Survival In Vitro and Remyelination In Vivo

Maintaining the normal function of oligodendrocyte precursor cells (OPCs) and protecting OPCs from damage is the basis of myelin regeneration in multiple sclerosis (MS). In this paper, we investigated the effect of stemazole, a novel small molecule, on the promotion of oligodendrocyte precursor cell survival and remyelination. The results show that stemazole enhanced the survival rate and the number of clone formation in a dose-dependent manner and decreased the percentage of cell apoptosis. In particular, the number of cell clones was increased up to 6-fold (p < 0.001) in the stemazole group compared with the control group. In vivo, we assessed the effect of stemazole on recovering the motor dysfunction and demyelination induced by cuprizone (CPZ). The results show that stemazole promoted the recovery of motor dysfunction and the repair of myelin sheaths. Compared with the CPZ group, the stemazole group showed a 30.46% increase in the myelin area (p < 0.001), a 37.08% increase in MBP expression (p < 0.01), and a 1.66-fold increase in Olig2 expression (p < 0.001). Histologically, stemazole had a better effect than the positive control drugs. In conclusion, stemazole promoted OPC survival in vitro and remyelination in vivo, suggesting that this compound may be used as a therapeutic agent against demyelinating disease.

A Quantitative Proteomic Approach Explores the Possible Mechanisms by Which the Small Molecule Stemazole Promotes the Survival of Human Neural Stem Cells

Neurodegenerative disorders have become a serious healthcare problem worldwide and there is no efficacious cure. However, regulating the fate of stem cells is an effective way to treat these neurological diseases. In previous work, stemazole was reported to maintain the survival of human neural stem cells in the absence of growth factors and to have therapeutic effects on neurodegenerative diseases. However, although it is a promising small molecule, the molecular mechanisms against apoptosis are ambiguous. In this study, tandem mass tag (TMT)-based proteomics were performed to obtain whole protein expression profiles of human neural stem cells in different groups under extreme conditions. Bioinformatics analysis based on protein–protein interaction (PPI) network construction, gene ontology (GO) and the Kyoto Encyclopaedia of Genes and Genomes (KEGG) pathway enrichment analysis were adopted to explore crucial proteins and possible pharmacological mechanisms. A total of 77 differentially expressed proteins were identified, comprising 38 upregulated proteins and 39 downregulated proteins. Combined with a diseases database of Alzheimer’s disease (AD), caspase-2 (CASP2), PKA C-alpha (PRKACA), fibronectin (FN1), large neutral amino acid transporter small subunit 1 (SLC7A5), which are involved in cell proliferation and apoptosis, this was further validated by enzyme activity assay and molecular docking, and regarded as putative targets regulated by stemazole. The present results give an insight into this small molecule and a better understanding for further elucidating the underlying mechanisms in the treatment of stem cells and neurodegenerative diseases.

A quantitative proteomics analysis for small molecule Stemazole's effect on human neural stem cells

BACKGROUND

Stemazole is a novel small molecule that has been suggested to have the ability to protect multiple stem cells. The proliferation-promoting activity and promising neuroprotective effects of stemazole make it a prospective drug for neurodegenerative disease treatment.

METHODS

Since previous studies have shown that it protective effect in extreme conditions, to understand more aspects of stemazole, in this study, a systematic tandem mass tags (TMT)-labelled proteomics approach was used to address the whole proteome expression profile with or without stemazole in normal conditions instead of extreme conditions. Bioinformatics analyses, including Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment and protein-protein interaction (PPI) network analyses, were employed.

RESULTS

The effect of stemazole on the expression profiles of neural stem cells was obtained. A total of 408 proteins with changes at the abundance level of two groups were identified: 178 proteins increase in abundance and 240 proteins decrease in abundance, respectively. Low abundance of some mitochondrial respiratory chain enzyme, overproduction of reactive oxygen species (ROS) and reduction of mitochondrial membrane potential may indicate stemazole has cytotoxicity.

CONCLUSIONS

It is the first proteomics research about stemazole, and the possible cytotoxicity of stemazole has been reported for the first time. The information about proteins that were affected by stemazole and more characteristics of stemazole will help obtain a complete picture of this small molecule drug. These findings provide a scientific basis for further stemazole treatment research.

Pyrola incarnata demonstrates neuroprotective effects against β-amyloid-induced memory impairment in mice

This study aims to investigate the neuroprotective effects of Pyrola incarnata against β-amyloid-induced memory impairment in mice. Ethanol extract of Pyrola incarnata (EPI) was obtained and led to eleven phytochemicals successfully by isolation and purification, which were elucidated by spectroscopic analysis (¹H NMR, ¹³C NMR and HR-ESI-MS). Thereinto, ursolic acid was gained as most abundant monomer. C57BL/6 mice were intracerebroventricular injected with aggregated Aβ_25-35. Open-field test, Barnes maze test and Morris water maze were conducted for evaluating cognition processes of EPI and ursolic acid. EPI significantly improved learning and memory deficits, attenuated the Aβ_25-35 level of deposition immunohistochemically. Further studies revealed that ursolic acid as bioactive phytochemical of P. incarnata improved spatial memory performance and ameliorated Aβ_25-35 accumulation by activating microglia cells and up-regulating Iba1 level in the hippocampus. These findings suggest P. incarnata could improve the cognition of mice and be a promising natural source for the treatment of neurodegenerative disease.

Uncovering the Pharmacological Mechanism of Stemazole in the Treatment of Neurodegenerative Diseases Based on a Network Pharmacology Approach

Stemazole exerts potent pharmacological effects against neurodegenerative diseases and protective effects in stem cells. However, on the basis of the current understanding, the molecular mechanisms underlying the effects of stemazole in the treatment of Alzheimer's disease and Parkinson's disease have not been fully elucidated. In this study, a network pharmacology-based strategy integrating target prediction, network construction, gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses, and molecular docking was adopted to predict the targets of stemazole relevant to the treatment of neurodegenerative diseases and to further explore the involved pharmacological mechanisms. The majority of the predicted targets were highly involved in the mitogen-activated protein kinase (MAPK) signaling pathway. RAC-alpha serine/threonine-protein kinase (AKT1), caspase-3 (CASP3), caspase-8 (CASP8), mitogen-activated protein kinase 8 (MAPK8), and mitogen-activated protein kinase 14 (MAPK14) are the core targets regulated by stemazole and play a central role in its anti-apoptosis effects. This work provides a scientific basis for further elucidating the mechanism underlying the effects of stemazole in the treatment of neurodegenerative diseases.

Stem Cell Therapy for Alzheimer's Disease

Alzheimer's disease (AD) is the most common neurodegenerative disease caused by eventually aggregated amyloid β (Aβ) plaques in degenerating neurons of the aging brain. These aggregated protein plaques mainly consist of Aβ fibrils and neurofibrillary tangles (NFTs) of phosphorylated tau protein. Even though some cholinesterase inhibitors, NMDA receptor antagonist, and monoclonal antibodies were developed to inhibit neurodegeneration or activate neural regeneration or clear off the Aβ deposits, none of the treatment is effective in improving the cognitive and memory dysfunctions of the AD patients. Thus, stem cell therapy represents a powerful tool for the treatment of AD. In addition to discussing the advents in molecular pathogenesis and animal models of this disease and the treatment approaches using small molecules and immunoglobulins against AD, we will focus on the stem cell sources for AD using neural stem cells (NSCs); embryonic stem cells (ESCs); and mesenchymal stem cells (MSCs) from bone marrow, umbilical cord, and umbilical cord blood. In particular, patient-specific-induced pluripotent stem cells (iPS cells) are proposed as a future prospective and the challenges for the treatment of AD.

Pharmacokinetics and absolute oral bioavailability of stemazole by UPLC-MS/MS and its bio-distribution through tritium labeling

The small molecule, stemazole, has significant therapeutic effects on neurodegenerative diseases, such as Alzheimer's disease (AD), due to its neuroprotective effects and remarkable survival-promoting activity in stem cells. However, pharmacokinetic properties of stemazole were unclear. In this study, a rapid and effective ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed to detect stemazole. The detector was operated in the positive-ion mode with an electrospray ionization (ESI) interface in multiple reaction monitoring (MRM) mode. Chromatographic separation was performed on an Acquity UPLC^® BEH C₁₈ column with gradient elution. Stemazole was extracted from plasma following a one-step protein precipitation method. The method was fully validated for its selectivity, specificity, and sensitivity. The calibration curve range of 5-1125 ng/mL showed good linearity for stemazole. Intra-day and inter-day precision rates were less than 10%, and accuracy ranged from 95.87% to 105.23%. The pharmacokinetic profiles were illustrated through the newly developed method for the first time. The absolute oral bioavailability of stemazole is 32.10%. Therefore, it is feasible as an oral medication, which greatly facilitates its broad application. The biological distribution of tritium-labeled stemazole in mice was studied, and the results showed that stemazole was absorbed rapidly and distributed widely, mainly in the liver and kidneys. A specific amount was also detected in the brain, which provides a prerequisite for the use of stemazole to treat neurodegenerative diseases. This work represents first description of the pharmacokinetics, bioavailability, and tissue distribution of stemazole and will lay the foundation for further investigation and drug development.

Protective role of Apelin-13 on amyloid β25-35-induced memory deficit; Involvement of autophagy and apoptosis process

Alzheimer's disease (AD) by progressive neurodegenerative pattern is associated with autophagy stress which is suggested as a potential cause of amyloid β (Aβ) aggregation and neural loss. Apelin-13, a neuropeptide with modulatory effect on autophagy, has been shown the beneficial effects on neural cell injuries. We investigated the effect of Apelin-13 on Aβ-induced memory deficit as well as autophagy and apoptosis processes. We performed bilateral intra-CA1 injection of Aβ25-35 alone or in combination with Apelin-13. Spatial reference and working memory was evaluated using the Morris water maze (MWM) and Y-maze tests. Hippocampus was harvested on 2, 5, 10 and 21 days after Aβ injection. The light chain 3 (LC3II/I) ratio, histone deacetylase 6 (HDAC6) level, Caspase-3 cleavage, and mTOR phosphorylation were assessed using western blot technique. Intra-CA1 injection of Aβ caused impairment of working and spatial memory. We observed higher LC3II/I ratio, cleaved caspase-3 and lower HDAC6, and p-mTOR/mTOR ratio in Aβ-treated animals. Apelin-13 provided significant protection against the destructive effects of Aβ on working and spatial memory. Apelin-13 prevented the increase of LC3II/I ratio and cleaved caspase-3 on days 10 and 21 after injection of Aβ. It also limited the Aβ-induced reduction in HDAC6 expression. This implies that Apelin-13 has suppressed both autophagy and apoptosis. Our findings suggested that the neuroprotection of Apelin-13 may be in part related to autophagy and apoptosis inhibition via the mTOR signaling pathway. Apelin-13 may be a promising approach to improve memory impairment and potentially pave the way for new therapeutic plans in AD.

miR-1247-3p mediates apoptosis of cerebral neurons by targeting caspase-2 in stroke

Brain stroke is one of the leading causes of death worldwide. We explored a potential stroke-related role for a newly found microRNA, miR-1247-3p, and one of its target genes, caspase-2, predicted by TargetScanVert. In the present study, we found that miR-1247-3p was downregulated during ischemia/reperfusion (I/R) and that LV-miR-1247-3p overexpression attenuated brain impairment induced by I/R. Similar results were observed in neuro2a (N2a) cells treated with oxygen-glucose deprivation/reoxygenation (OGD/R). Caspase-2 was upregulated in the I/R and OGD/R model, while Z-VDVAD-FMK - the inhibitor of caspase-2-inhibited apoptosis of N2a cells induced by OGD/R. An miR-1247-3p mimic inhibited caspase-2 expression and attenuated apoptosis of N2a cells induced by OGD/R. Myocardin-related transcription factor-A (MRTF-A) overexpression upregulated miR-1247 and mature miR-1247-3p levels and attenuated apoptosis induced by OGD/R, whereas its anti-apoptotic function could be blocked by a miR-1247-3p inhibitor. Hence, we conclude that miR-1247-3p may protect cells during brain stroke. This study offers insights for the development of effective therapeutics for promoting the survival of cerebral neurons during brain I/R injury.

Subtle Alterations in Spatial Memory Induced by Amyloid Peptides Infusion in Rats

The cause of Alzheimer's disease (AD) remains uncertain. The accumulation of amyloid peptides (Aβ) is the main pathophysiological hallmark of the disease. Spatial deficit is an important initial sign of AD, while other types of memory impairments that appear in later stages. The Barnes maze allows the detection of subtle alterations in spatial search by the analysis of use of different strategies. Previous findings showed a general performance deficit in this task following long-term (35 days) infusion of Aβ, which corresponds to the moderate or severe impairments of the disease. In the present study, we evaluated the effects of a low-dose 15-day long treatment with Aβ peptides on spatial and non-spatial strategies of rats tested in the Barnes maze. Aβ peptides (0.5 μL/site/day; 30 pmoL solution of Aβ1-40:Aβ1-42 10:1) or saline were bilaterally infused into the CA1 (on the first treatment day) and intraventricularly (on the following 15 days) in 6-month-old Wistar male rats. Aβ infusion induced a deficit in the performance (increased latency and distance traveled to reach the target compared to saline group). In addition, a significant association between treatment and search strategy in the retrieval trial was found: Aβ group preferred the non-spatial search strategy, while saline group preferred the spatial search. In conclusion, the protocol of Aβ infusion used here induced a subtle cognitive deficit that was specific to spatial aspects. Indeed, animals under Aβ treatment still showed retrieval, but using non-spatial strategies. We suggest that this approach is potentially useful to the study of the initial memory deficits in early AD.

Stemazole promotes survival and preserves stemness in human embryonic stem cells

Human embryonic stem cells (hESCs) are extremely delicate, and survive poorly under suboptimal culture conditions, severely restricting long-term studies and practical applications. Thus, a protective agent that promotes stem cell survival is urgently needed. In this study, we evaluated the protective effects of stemazole in single-cell and starved hESC cultures. Colony formation was quantified by alkaline phosphatase and immunofluorescence staining, while apoptosis was assessed by flow cytometry and TUNEL assay. Expression of hESC and other stem cell markers was evaluated by western blot, RT-PCR, and qPCR. We found that stemazole enhanced clonal expansion from single cells in dose-dependent fashion and clearly decreased apoptosis from 54.1% to 25.2%. Furthermore, the drug reduced apoptosis from 43.6% to 8.4% over 15 h of starvation, with 66% of stemazole-treated cells remaining viable after 2 weeks of starvation. Importantly, starved cells protected with stemazole retained the same proliferation and differentiation properties as cells in normal culture. In conclusion, stemazole significantly promotes survival of stem cells in single-cell or starvation cultures without compromising stemness and pluripotency.

Kai Xin San aqueous extract improves Aβ1-40-induced cognitive deficits on adaptive behavior learning by enhancing memory-related molecules expression in the hippocampus

ETHNOPHARMACOLOGICAL RELEVANCE

Kai Xin San (KXS), a traditional formula of Chinese medicine, has been used to treat dementia.

AIM OF THE STUDY

The present study aimed to investigate its ameliorating effects on Aβ_1-40-induced cognitive impairment in rats using a series of novel reward-directed instrumental learning tasks, and to determine its possible mechanism of action.

MATERIALS AND METHODS

Rats were pretreated with KXS aqueous extract (0.72 and 1.44g/kg, p.o.) for 10 days, and were trained to gain reward reinforcement by lever pressing at the meantime. Thereafter, rats received a bilateral microinjection of Aβ_1-40 in CA1 regions of the hippocampus. Cognitive performance was evaluated with the goal directed (higher response ratio) and habit (visual signal discrimination and extinction) learning tasks, as well as on the levels of memory-related biochemical parameters and molecules.

RESULTS

Our findings first demonstrated that KXS can improve Aβ_1-40-induced amnesia in RDIL via enhancing the comprehension of action-outcome association and the utilization of cue information to guide behavior. Then, its ameliorating effects should be attributed to the modulation of memory-related molecules in the hippocampus.

CONCLUSION

In conclusion, KXS has the potential to prevent and/or delay the deterioration of cognitive impairment in AD.

Therapies for Prevention and Treatment of Alzheimer's Disease

Alzheimer's disease (AD) is the most common cause of dementia associated with a progressive neurodegenerative disorder, with a prevalence of 44 million people throughout the world in 2015, and this figure is estimated to double by 2050. This disease is characterized by blood-brain barrier disruption, oxidative stress, mitochondrial impairment, neuroinflammation, and hypometabolism; it is related to amyloid-β peptide accumulation and tau hyperphosphorylation as well as a decrease in acetylcholine levels and a reduction of cerebral blood flow. Obesity is a major risk factor for AD, because it induces adipokine dysregulation, which consists of the release of the proinflammatory adipokines and decreased anti-inflammatory adipokines, among other processes. The pharmacological treatments for AD can be divided into two categories: symptomatic treatments such as acetylcholinesterase inhibitors and N-methyl-D-aspartate (NMDA) receptor antagonists and etiology-based treatments such as secretase inhibitors, amyloid binders, and tau therapies. Strategies for prevention of AD through nonpharmacological treatments are associated with lifestyle interventions such as exercise, mental challenges, and socialization as well as caloric restriction and a healthy diet. AD is an important health issue on which all people should be informed so that prevention strategies that minimize the risk of its development may be implemented.

The role of myocardin-related transcription factor-A in Aβ25-35 induced neuron apoptosis and synapse injury

Myocardin-related transcription factor-A (MRTF-A) highly expressed in brain has been demonstrated to promote neuronal survival via regulating the transcription of related target genes as a powerful co-activator of serum response factor (SRF). However, the role of MRTF-A in Alzheimer's disease (AD) is still unclear. Here, we showed that MRTF-A was significantly downregulated in cortex of the Aβ25-35-induced AD rats, which played a key role in Aβ25-35 induced cerebral neuronal degeneration in vitro. Bilateral intracerebroventricular injection of Aβ25-35 caused significantly MRTF-A expression decline in cortex of rats, along with significant neuron apoptosis and plasticity damage. In vitro, transfection of MRTF-A into primary cultured cortical neurons prevented Aβ25-35 induced neuronal apoptosis and synapses injury. And luciferase reporter assay determined that MRTF-A could bind to and enhance the transactivity of the Mcl-1 (Myeloid cell leukemia-1) and Arc (activity-regulated cytoskeletal-associated protein) promoters by activating the key CArG box element. These data demonstrated that the decreasing of endogenous MRTF-A expression might contribute to the development of AD, whereas the upregulation MRTF-A in neurons could effectively reduce Aβ25-35 induced synapse injury and cell apoptosis. And the underlying mechanism might be partially due to MRTF-A-mediated the transcription and expression of Mcl-1 and Arc by triggering the CArG box.

Ovarian hormones ameliorate memory impairment, cholinergic deficit, neuronal apoptosis and astrogliosis in a rat model of Alzheimer's disease

Ovarian hormones, including progesterone (P4) and 17 β-estradiol (E2), have been shown to affect memory functions; however, the underlying mechanism whereby ovarian hormone replacement therapy may decrease the risk of Alzheimer's disease (AD) is currently unclear. The present study aimed to investigate the effects of P4 and E2 on spatial and learning memory in an ovariectomized rat model of AD. β-amyloid (Aβ) or saline were stereotaxically injected into the hippocampus of the rats and, after 1 day, ovariectomy or sham operations were performed. Subsequently, the rats were treated with P4 alone, E2 alone, or a combination of P4 and E2. Treatment with E2 and/or P4 was shown to improve the learning and memory functions of the rats, as demonstrated by the Morris water maze test. In addition, treatment with E2 and P4 was associated with increased expression levels of choline acetyltransferase and 5-hydroxytryptamine receptor 2A (5-HT2A), and decreased expression levels of the glial fibrillary acidic protein in the hippocampus of the rats. Furthermore, E2 and P4 treatment significantly attenuated neuronal cell apoptosis, as demonstrated by terminal deoxynucleotidyl transferase dUTP nick end labeling assays; thus suggesting that the ovarian hormones were able to protect against Aβ-induced neuronal cell toxicity. The results of the present study suggested that the neuroprotective effects of P4 and E2 were associated with amelioration of the cholinergic deficit, suppression of apoptotic signals and astrogliosis, and upregulation of 5-HT2A expression levels. Therefore, hormone replacement therapy may be considered an effective strategy for the treatment of patients with cognitive disorders and neurodegenerative diseases.

Angelica sinensis reduced Aβ-induced memory impairment in rats

BACKGROUND

Studies have shown that Angelica sinensis (JiLin AoDong Medicine Industry Groups Co., Ltd., Jilin, China) root (AS) ameliorates various diseases, although its effects in Alzheimer's disease (AD) have not been elucidated.

PURPOSE

The present study examined the effects of AS in a rat model of AD.

METHODS

Positional Aβ injections were administered to rats. The behavioral effects of AS administration were examined using the Morris water maze, and the molecular effects on gene and protein expression, and apoptosis, were determined.

RESULTS

AS reversed the social behavioral impairments observed in this rat model of Aβ-induced memory impairment. Western blot analysis also revealed lower hippocampal levels of Aβ and β-site amyloid precursor protein-cleaving enzyme. Terminal deoxynucleotidyl transferased UTP nick end labeling indicated that AS significantly inhibited apoptosis via effects on nuclear factor kappa B (NF-κB) signaling. Real-time PCR, enzyme-linked immunosorbent assay, and immunohistochemical staining indicated that AS effectively inhibited inflammation and upregulated expression of glial cell line-derived neurotrophic factor (GDNF) and brain-derived neurotrophic factor (BDNF) in the hippocampus of this rat AD model.

DISCUSSION

AS effectively rescued the symptoms of AD in a rat model by inhibiting inflammation, apoptosis, and NF-κB signaling pathway.

CONCLUSION

These findings suggested that AS could provide a potential drug for the treatment of AD.

Protective Effects of Baicalin on Aβ₁₋₄₂-Induced Learning and Memory Deficit, Oxidative Stress, and Apoptosis in Rat

The accumulation and deposition of β-amyloid peptide (Aβ) in senile plaques and cerebral vasculature is believed to facilitate the progressive neurodegeneration that occurs in the Alzheimer's disease (AD). The present study sought to elucidate possible effects of baicalin, a natural phytochemical, on Aβ toxicity in a rat model of AD. By morris water maze test, Aβ1-42 injection was found to cause learning and memory deficit in rat, which was effectively improved by baicalin treatment. Besides, histological examination showed that baicalin could attenuate the hippocampus injury caused by Aβ. The neurotoxicity mechanism of Aβ is associated with oxidative stress and apoptosis, as revealed by increased malonaldehyde generation and TUNEL-positive cells. Baicalin treatment was able to increase antioxidant capabilities by recovering activities of antioxidant enzymes (superoxide dismutase, catalase, and glutathione peroxidase) and up-regulating their gene expression. Moreover, baicalin effectively prevented Aβ-induced mitochondrial membrane potential decrease, Bax/Bcl-2 ratio increase, cytochrome c release, and caspase-9/-3 activation. In addition, we found that the anti-oxidative effect of baicalin was associated with Nrf2 activation. In conclusion, baicalin effectively improved Aβ-induced learning and memory deficit, hippocampus injury, and neuron apoptosis, making it a promising drug to preventive interventions for AD.

Tong Luo Jiu Nao ameliorates Aβ1-40-induced cognitive impairment on adaptive behavior learning by modulating ERK/CaMKII/CREB signaling in the hippocampus

BACKGROUND

Tong Luo Jiu Nao (TLJN), a modern formula of Chinese medicine extracts on the basis of Traditional Chinese Medicine theory, has been used to treat dementia. The present study aimed to investigate its ameliorating effects on Aβ1-40-induced cognitive impairment in rats using a series of novel reward-directed instrumental learning (RDIL) tasks, and to determine its possible mechanism of action.

METHODS

Rats were pretreated with TLJN extract (0.9 and 1.8 g/kg, p.o.) for 10 daysbefore surgery, and were trained to gain reward reinforcement by lever pressing at the meantime. Thereafter, rats received a bilateral microinjection of Aβ1-40 in CA1 regions of the hippocampus. Cognitive performance was evaluated with the goal directed (higher response ratio) and habit (visual signal discrimination and extinction) learning tasks, as well as on the levels of biochemical parameters and molecules.

RESULTS

Our findings first demonstrated that TLJN can improve Aβ1-40-induced amnesia in RDIL via enhancing the comprehension of action-outcome association and the utilization of cue information to guide behavior. Then, its ameliorating effects should attribute to the modulation of ERK/CaMKII/CREB signaling in the hippocampus.

CONCLUSION

TLJN can markedly enhance cognitions of Aβ1-40 microinjection animal model in adaptive behavioral tasks. It has the potential, possibly as complementary and alternative therapy, to prevent and/or delay the deterioration of cognitive impairment in AD.

Neuroprotective effect of the active components of three Chinese herbs on brain iron load in a mouse model of Alzheimer's disease

Alzheimer’s disease (AD) is a neurodegenerative brain disorder and the most common cause of dementia. New treatments for AD are required due to its increasing prevalence in aging populations. The present study evaluated the effects of the active components of Epimedium, Astragalus and Radix Puerariae on learning and memory impairment, β-amyloid (Aβ) reduction and brain iron load in an APP_swe/PS1_ΔE9 transgenic mouse model of AD. Increasing evidence indicates that a disturbance of normal iron homeostasis may contribute to the pathology of AD. However, the underlying mechanisms resulting in abnormal iron load in the AD brain remain unclear. It has been hypothesized that the brain iron load is influenced by the deregulation of certain proteins associated with brain iron metabolism, including divalent metal transporter 1 (DMT1) and ferroportin 1 (FPN1). The present study investigated the effects of the active components of Epimedium, Astragalus and Radix Puerariae on the expression levels of DMT1 and FPN1. The treatment with the active components reduced cognitive deficits, inhibited Aβ plaque accumulation, reversed Aβ burden and reduced the brain iron load in AD model mice. A significant increase was observed in the levels of DMT1-iron-responsive element (IRE) and DMT1-nonIRE in the hippocampus of the AD mouse brain, which was reduced by treatment with the active components. In addition, the levels of FPN1 were significantly reduced in the hippocampus of the AD mouse brain compared with those of control mice, and these levels were increased following treatment with the active components. Thus, the present study indicated that the active components of Epimedium, Astragalus and Radix Puerariae may exert a neuroprotective effect against AD by reducing iron overload in the AD brain and may provide a novel approach for the development of drugs for the treatment of AD.

The neuroprotective effects of β-hydroxybutyrate on Aβ-injected rat hippocampus in vivo and in Aβ-treated PC-12 cells in vitro

Alzheimer's disease is a neurodegenerative disorder associated with the deposition of the peptide amyloid-beta (Aβ) in senile plaques and cerebral vasculature. The neurotoxic mechanisms of this condition have been linked to oxidative-stress-induced apoptosis leading to widespread neuronal loss. Herein, we demonstrate the neuroprotective effects of a ketone body D-β-hydroxybutyrate (β-HB) in neural cell lines and an animal model induced by injecting Aβ into the hippocampus. Using histological examination and the TUNEL assay, we show that administration of exogenous β-HB effectively prevents Aβ deposition and neuron apoptosis in this rat model. β-HB pretreatment also relieves the oxidative stress in Aβ-induced PC-12 cells, as shown by decreased intracellular reactive oxygen species and Ca(2+) levels, activated Nrf2 and recovered superoxide dismutase and catalase activities. Consequently, the apoptotic pathway is also inhibited in these cells, with decreased levels of p53, caspase-12, caspase-9, caspase-3; a decreased Bax/Bcl-2 ratio; and decreased cytochrome c release. Taken together, our study provides a molecular basis for the neuroprotective effects of β-HB in line with the suppression of oxidative stress and the inhibition of apoptotic protein activation.

Behavioral assays with mouse models of Alzheimer's disease: practical considerations and guidelines

In Alzheimer's disease (AD) basic research and drug discovery, mouse models are essential resources for uncovering biological mechanisms, validating molecular targets and screening potential compounds. Both transgenic and non-genetically modified mouse models enable access to different types of AD-like pathology in vivo. Although there is a wealth of genetic and biochemical studies on proposed AD pathogenic pathways, as a disease that centrally features cognitive failure, the ultimate readout for any interventions should be measures of learning and memory. This is particularly important given the lack of knowledge on disease etiology - assessment by cognitive assays offers the advantage of targeting relevant memory systems without requiring assumptions about pathogenesis. A multitude of behavioral assays are available for assessing cognitive functioning in mouse models, including ones specific for hippocampal-dependent learning and memory. Here we review the basics of available transgenic and non-transgenic AD mouse models and detail three well-established behavioral tasks commonly used for testing hippocampal-dependent cognition in mice - contextual fear conditioning, radial arm water maze and Morris water maze. In particular, we discuss the practical considerations, requirements and caveats of these behavioral testing paradigms.

Modeling Alzheimer's disease with non-transgenic rat models

Alzheimer's disease (AD), for which there is no cure, is the most common form of dementia in the elderly. Despite tremendous efforts by the scientific community, the AD drug development pipeline remains extremely limited. Animal models of disease are a cornerstone of any drug development program and should be as relevant as possible to the disease, recapitulating the disease phenotype with high fidelity, to meaningfully contribute to the development of a successful therapeutic agent. Over the past two decades, transgenic models of AD based on the known genetic origins of familial AD have significantly contributed to our understanding of the molecular mechanisms involved in the onset and progression of the disease. These models were extensively used in AD drug development. The numerous reported failures of new treatments for AD in clinical trials indicate that the use of genetic models of AD may not represent the complete picture of AD in humans and that other types of animal models relevant to the sporadic form of the disease, which represents 95% of AD cases, should be developed. In this review, we will discuss the evolution of non-transgenic rat models of AD and how these models may open new avenues for drug development.

Salidroside attenuates beta amyloid-induced cognitive deficits via modulating oxidative stress and inflammatory mediators in rat hippocampus

Beta amyloid (Aβ)-induced oxidative stress and chronic inflammation in the brain are considered to be responsible for the pathogenesis of Alzheimer's disease (AD). Salidroside, the major active ingredient of Rhodiola crenulata, has been previously shown to have antioxidant and neuroprotective properties in vitro. The present study aimed to investigate the protective effects of salidroside on Aβ-induced cognitive impairment in vivo. Rats received intrahippocampal Aβ1-40 injection were treated with salidroside (25, 50 and 75 mg/kg p.o.) once daily for 21 days. Learning and memory performance were assessed in the Morris water maze (days 17-21). After behavioral testing, the rats were sacrificed and hippocampi were removed for biochemical assays (reactive oxygen species (ROS), superoxide dismutase (SOD), glutathione peroxidase (GPx), malondialdehyde (MDA), acetylcholinesterase (AChE), acetylcholine (ACh)) and molecular biological analysis (Cu/Zn-SOD, Mn-SOD, GPx, nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, nuclear factor κB (NF-κB), inhibitor of κB-alpha (IκBα), cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), receptor for advanced glycation end products (RAGE)). Our results confirmed that Aβ1-40 peptide caused learning and memory deficits in rats. Further analysis demonstrated that the NADPH oxidase-mediated oxidative stress was increased in Aβ1-40-injected rats. Furthermore, NF-κB was demonstrated to be activated in Aβ1-40-injected rats, and the COX-2, iNOS and RAGE expression were also induced by Aβ1-40. However, salidroside (50 and 75 mg/kg p.o.) reversed all the former alterations. Thus, the study indicates that salidroside may have a protective effect against AD via modulating oxidative stress and inflammatory mediators.

Fucoidan, a sulfated polysaccharide from brown algae, improves cognitive impairment induced by infusion of Aβ peptide in rats

Fucoidan is a complex sulfated polysaccharide, derived from marine brown seaweed. In the present study, we investigated the effects of fucoidan on improving learning and memory impairment in rats induced by infusion of Aβ (1-40), and its possible mechanisms. The results indicated that fucoidan could ameliorate Aβ-induced learning and memory impairment in animal behavioral tests. Furthermore, fucoidan reversed the decreased activity of choline acetyl transferase (ChAT), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and content of acetylcholine (Ach), as well as the increased activity of acetylcholine esterase (AchE) and content of malondialdehyde (MDA) in hippocampal tissue of Aβ-injected rats. Moreover, these were accompanied by an increase of Bcl-2/Bax ratio and a decrease of caspase-3 activity. These results suggested that fucoidan could ameliorate the learning and memory abilities in Aβ-induced AD rats, and the mechanisms appeared to be due to regulating the cholinergic system, reducing oxidative stress and inhibiting the cell apoptosis.