Impact of apolipoprotein E isoforms on sporadic Alzheimer's disease:beyond the role of amyloid beta

The impact of apolipoprotein E(ApoE)isoforms on sporadic Alzheimer's disease has long been studied;however,the influences of apolipoprotein E gene(APOE)on healthy and pathological human brains are not fully understood.ApoE exists as three common isoforms(ApoE2,ApoE3,and ApoE4),which differ in two amino acid residues.Traditionally,ApoE binds cholesterol and phospholipids and ApoE isoforms display diffe rent affinities for their receptors,lipids transport and distribution in the brain and periphery.The role of ApoE in the human depends on ApoE isoforms,brain regions,aging,and neural injury.APOE E4 is the strongest genetic risk factor for sporadic Alzheimer's disease,considering its role in influencing amyloid-beta metabolism.The exact mechanisms by which APOE gene variants may increase or decrease Alzheimer's disease risk are not fully understood,but APOE was also known to affect directly and indirectly tau-mediated neurodegeneration,lipids metabolism,neurovascular unit,and microglial function.Consistent with the biological function of ApoE,ApoE4 isoform significantly alte red signaling pathways associated with cholesterol homeostasis,transport,and myelination.Also,the rare protective APOE variants confirm that ApoE plays an important role in Alzheimer's disease pathogenesis.The objectives of the present mini-review were to describe classical and new roles of various ApoE isoforms in Alzheimer's disease pathophysiology beyond the deposition of amyloid-beta and to establish a functional link between APOE,brain function,and memory,from a molecular to a clinical level.APOE genotype also exerted a heterogeneous effect on clinical Alzheimer's disease phenotype and its outcomes.Not only in learning and memory but also in neuro psychiatric symptoms that occur in a premorbid condition.Cla rifying the relationships between Alzheimer's disease-related pathology with neuropsychiatric symptoms,particularly suicidal ideation in Alzheimer's disease patients,may be useful for elucidating also the underlying pathophysiological process and its prognosis.Also,the effects of anti-amyloid-beta drugs,recently approved for the treatment of Alzheimer's disease,could be influenced by the APOE genotype.

Jiaohong pills attenuate neuroinflammation and amyloid-βprotein-induced cognitive deficits by modulating the mitogen-activated protein kinase/nuclear factor kappa-B pathway

Background:Jiaohong pills(JHP)consist of Pericarpium Zanthoxyli(PZ)and Radix Rehmanniae,two herbs that have been extensively investigated over many years due to their potential protective effects against cognitive decline and memory impairment.However,the precise mechanisms underlying the beneficial effects remain elusive.Here,research studies were conducted to investigate and validate the therapeutic effects of JHP on Alzheimer's disease.Methods:BV-2 cell inflammation was induced by lipopolysaccharide.AD mice were administered amyloid-β(Aβ).Behavioral experiments were used to evaluate learning and memory ability.The levels of nitric oxide(NO),tumor necrosis factor-alpha(TNF-α),interleukin-1β(IL-1β),and interleukin-10(IL-10)were detected using enzymelinked immunosorbent assay(ELISA).The protein expressions of inducible nitric oxide synthase(iNOS)and the phosphorylation level of mitogen-activated protein kinase(MAPK)and nuclear factor kappa-B(NF-κB)were detected using Western blot.Nissl staining was used to detect neuronal degeneration.Results:The results demonstrated that an alcoholic extract of PZ significantly decreased the levels of NO,IL-1β,TNF-α,and iNOS;increased the expression level of IL-10;and significantly decreased the phosphorylation levels of MAPK and NF-κB.These inhibitory effects were further confirmed in the AD mouse model.Meanwhile,JHP improved learning and memory function in AD mice,reduced neuronal damage,and enriched the Nissl bodies in the hippocampus.Moreover,IL-1βand TNF-αin the cortex were significantly downregulated after JHP administration,whereas IL-10showed increased expression.Conclusions:It was found that JHP reduced neuroinflammatory response in AD mice by targeting the MAPK/NF-κB signaling pathway.

Role of peripheral amyloid-β aggregates in Alzheimer’s disease: mechanistic, diagnostic, and therapeutic implications

Compelling evidence demonstrates that the levels of peripheral amyloid-β(Aβ)fluctuate in Alzheimer’s disease(AD)patients.Moreover,Aβdeposits have been identified in peripheral tissues.However,the relevance of peripheral Aβ(misfolded or not)in pathological situations,and the temporal appearance of these pathological fluctuations,are not well understood.The presence of misfolded Aβin peripheral compartments raises concerns on potential inter-individual transmissions considering the well-reported prion-like properties of this disease-associated protein.The latter is supported by multiple reports demonstrating that Aβmisfolding can be transmitted between humans and experimental animals through multiple routes of exposure.In this mini-review,we discuss the potential implications of peripheral,disease-associated Aβin disease mechanisms,as well as in diagnostic and therapeutic approaches.

Misfolded amyloid-beta conformational variants(strains)as drivers of Alzheimer's disease neuropathology

Pathological and clinical variability in Alzheimer's disease(AD):AD is clinically cha racterized by progressive memory loss and cognitive impairment.From a pathological point of view,the main features of AD are the deposition of amyloid plaques(composed of amyloid-beta,Aβ)and neurofibrillary tangles containing hyperphosphorylated Tau in the brain,accompanied by neu ronal and synaptic loss,neuroinflammation and brain atrophy(Jellinger,2022).Regardless of these common traits,growing evidence shows increased heterogen eity in the brain of AD patients considering both clinical manifestations and pathological features.

Design and redesign journey of a drug for transthyretin amyloidosis

The misfolding and subsequent aggregation of proteins into amyloid fibrils underlie the onset of a variety of human disorders collectively known as amyloidosis.Transthyretin(TTR)is one of the>30 amyloidogenic proteins identified to date and is associated with a group of highly debilitating and life-threatening disorders called TTR amyloidosis(ATTR).ATTR comprises senile systemic amyloidosis,which is linked to wild-type(WT)TTR aggregation,and hereditary ATTR,a dominantly inherited disorder caused by the deposition of one of over 130 TTR genetic variants.Senile systemic amyloidosis is a prevalent age-related amyloidosis,affecting up to 25%of the population over 80 years of age,and is characterized by the build-up of TTR fibrils in the myocardium.Regarding hereditary ATTR,the clinical presentation is highly heterogeneous,primarily affecting the peripheral nervous system(familial amyloid polyneuropathy-FAP)or the heart(familial amyloid cardiomyopathy).In rare cases,aggregation develops in the central nervous system,giving rise to a phenotype known as familial leptomeningeal amyloidosis(Carroll et al.,2022).

Corrigendum: Activation of autophagy by Citri Reticulatae Semen extract ameliorates amyloid-beta-induced cell death and cognition deficits in Alzheimer’s disease

In the article titled“Activation of autophagy by Citri Reticulatae Semen extract ameliorates amyloid-beta-induced cell death and cognition deficits in Alzheimer’s disease”published on pages 2467-2479,Issue 11,Volume 19 of Neural Regeneration Research(Tang et al.,2024),there are some errors in selecting the appropriate images in Figure 7 by authors during assembling the images.

Anti-amyloid antibodies in Alzheimer’s disease: what did clinical trials teach us?

Although many causes of Alzheimer’s disease(AD)may exist,both the original amyloid cascade and tau hypotheses posit that abnormal misfolding and accumulation of amyloid-β(Aβ)and tau protein is the central event causing the pathology.However,that conclusion could be only partly true,and there is conflicting evidence about the role of both proteins in AD,being able to precede and influence one another.Some researchers argue that these proteins are mere executors rather than primary causes of pathology.Therefore,there have been continuing refinements of both hypotheses,with alternative explanations proposed.Aβand tau proteins may be independently involved in specific neurotoxic pathways;yet there may be other crucial processes going on in early AD.Moreover,accumulating evidence suggests that Aβand tau act synergistically,rather than additively in disease onset(Jeremic et al.,2021,2023a).

Beyond neurodegeneration:engineering amyloids for biocatalysis

Amyloid fibrils are highly organized protein or peptide aggregates,often characterized by a distinctive supramolecular cross-β-sheet structure.The formation and accumulation of these structures have been traditionally associated with neural or systemic human diseases,such as Alzheimer’s disease,Parkinson’s disease,type-2 diabetes,or amyotrophic lateral sclerosis(Wei et al.,2017;Wittung-Stafshede,2023).

Protein nanoparticles as potent delivery vehicles for polycytosine RNA-binding protein one

Ma et al recently reported in the World Journal of Diabetes that ferroptosis occurs in osteoblasts under high glucose conditions,reflecting diabetes pathology.This condition could be protected by the upregulation of the gene encoding polycytosine RNA-binding protein 1(PCBP1).Additionally,Ma et al used a lentivirus infection system to express PCBP1.As the authors’method of administration can be improved in terms of stability and cost,we propose delivering PCBP1 to treat type 2 diabetic osteoporosis by encapsulating it in protein nanoparticles.First,PCBP1 is small and druggable.Second,intravenous injection can help deliver PCBP1 across the mucosa while avoiding acid and enzyme-catalyzed degradation.Furthermore,incorporating PCBP1 into nanoparticles prevents its interaction with water or oxygen and protects PCBP1’s structure and activity.Notably,the safety of the protein materials and the industrialization techniques for large-scale production of protein nanoparticles must be comprehensively investigated before clinical application.

RGS4 promotes the progression of gastric cancer through the focal adhesion kinase/phosphatidyl-inositol-3-kinase/protein kinase B pathway and epithelial-mesenchymal transition

BACKGROUND Regulator of G protein signaling(RGS)proteins participate in tumor formation and metastasis by acting on theα-subunit of heterotrimeric G proteins.The speci-fic effect of RGS,particularly RGS4,on the progression of gastric cancer(GC)is not yet clear.AIM To explore the role and underlying mechanisms of action of RGS4 in GC develop-ment.METHODS The prognostic significance of RGS4 in GC was analyzed using bioinformatics based public databases and verified by immunohistochemistry and quantitative polymerase chain reaction in 90 patients with GC.Function assays were employed to assess the carcinogenic impact of RGS4,and the mechanism of its possible influence was detected by western blot analysis.A nude mouse xenograft model was established to study the effects of RGS4 on GC growth in vitro.RESULTS RGS4 was highly expressed in GC tissues compared with matched adjacent normal tissues.Elevated RGS4 expression was correlated with increased tumor-node-metastasis stage,increased tumor grade as well as poorer overall survival in patients with GC.Cell experiments demonstrated that RGS4 knockdown suppressed GC cell proliferation,migration and invasion.Similarly,xenograft experiments confirmed that RGS4 silencing significantly inhibited tumor growth.Moreover,RGS4 knockdown resulted in reduced phosphorylation levels of focal adhesion kinase,phosphatidyl-inositol-3-kinase,and protein kinase B,decreased vimentin and N-cadherin,and elevated E-cadherin.CONCLUSION High RGS4 expression in GC indicates a worse prognosis and RGS4 is a prognostic marker.RGS4 influences tumor progression via the focal adhesion kinase/phosphatidyl-inositol-3-kinase/protein kinase B pathway and epithelial-mesenchymal transition.

Protein arginine methyltransferase-6 regulates heterogeneous nuclear ribonucleoprotein-F expression and is a potential target for the treatment of neuropathic pain

Protein arginine methyltransferase-6 participates in a range of biological functions,particularly RNA processing,transcription,chromatin remodeling,and endosomal trafficking.However,it remains unclear whether protein arginine methyl transferase-6 modifies neuropathic pain and,if so,what the mechanisms of this effect.In this study,protein arginine methyltransferase-6 expression levels and its effect on neuropathic pain were investigated in the spared nerve injury model,chronic constriction injury model and bone cancer pain model,using immunohistochemistry,western blotting,immunoprecipitation,and label-free proteomic analysis.The results showed that protein arginine methyltransferase-6 mostly co-localized withβ-tubulinⅢin the dorsal root ganglion,and that its expression decreased following spared nerve injury,chronic constriction injury and bone cancer pain.In addition,PRMT6 knockout(Prmt6~(-/-))mice exhibited pain hypersensitivity.Furthermore,the development of spared nerve injury-induced hypersensitivity to mechanical pain was attenuated by blocking the decrease in protein arginine methyltransferase-6 expression.Moreover,when protein arginine methyltransferase-6 expression was downregulated in the dorsal root ganglion in mice without spared nerve injury,increased levels of phosphorylated extracellular signal-regulated kinases were observed in the ipsilateral dorsal horn,and the response to mechanical stimuli was enhanced.Mechanistically,protein arginine methyltransferase-6 appeared to contribute to spared nerve injury-induced neuropathic pain by regulating the expression of heterogeneous nuclear ribonucleoprotein-F.Additionally,protein arginine methyltransfe rase-6-mediated modulation of hete rogeneous nuclear ribonucleoprotein-F expression required amino atids 319 to 388,but not classical H3R2 methylation.These findings indicated that protein arginine methyltransferase-6 is a potential therapeutic target fo r the treatment of peripheral neuro pathic pain.

Exploring the interaction between the gut microbiota and cyclic adenosine monophosphate-protein kinase A signaling pathway:a potential therapeutic approach for neurodegenerative diseases

The interaction between the gut microbiota and cyclic adenosine monophosphate(cAMP)-protein kinase A(PKA)signaling pathway in the host's central nervous system plays a crucial role in neurological diseases and enhances communication along the gut–brain axis.The gut microbiota influences the cAMP-PKA signaling pathway through its metabolites,which activates the vagus nerve and modulates the immune and neuroendocrine systems.Conversely,alterations in the cAMP-PKA signaling pathway can affect the composition of the gut microbiota,creating a dynamic network of microbial-host interactions.This reciprocal regulation affects neurodevelopment,neurotransmitter control,and behavioral traits,thus playing a role in the modulation of neurological diseases.The coordinated activity of the gut microbiota and the cAMP-PKA signaling pathway regulates processes such as amyloid-β protein aggregation,mitochondrial dysfunction,abnormal energy metabolism,microglial activation,oxidative stress,and neurotransmitter release,which collectively influence the onset and progression of neurological diseases.This study explores the complex interplay between the gut microbiota and cAMP-PKA signaling pathway,along with its implications for potential therapeutic interventions in neurological diseases.Recent pharmacological research has shown that restoring the balance between gut flora and cAMP-PKA signaling pathway may improve outcomes in neurodegenerative diseases and emotional disorders.This can be achieved through various methods such as dietary modifications,probiotic supplements,Chinese herbal extracts,combinations of Chinese herbs,and innovative dosage forms.These findings suggest that regulating the gut microbiota and cAMP-PKA signaling pathway may provide valuable evidence for developing novel therapeutic approaches for neurodegenerative diseases.

Spastin and alsin protein interactome analyses begin to reveal key canonical pathways and suggest novel druggable targets

Developing effective and long-term treatment strategies for rare and complex neurodegenerative diseases is challenging. One of the major roadblocks is the extensive heterogeneity among patients. This hinders understanding the underlying disease-causing mechanisms and building solutions that have implications for a broad spectrum of patients. One potential solution is to develop personalized medicine approaches based on strategies that target the most prevalent cellular events that are perturbed in patients. Especially in patients with a known genetic mutation, it may be possible to understand how these mutations contribute to problems that lead to neurodegeneration. Protein–protein interaction analyses offer great advantages for revealing how proteins interact, which cellular events are primarily involved in these interactions, and how they become affected when key genes are mutated in patients. This line of investigation also suggests novel druggable targets for patients with different mutations. Here, we focus on alsin and spastin, two proteins that are identified as “causative” for amyotrophic lateral sclerosis and hereditary spastic paraplegia, respectively, when mutated. Our review analyzes the protein interactome for alsin and spastin, the canonical pathways that are primarily important for each protein domain, as well as compounds that are either Food and Drug Administration–approved or are in active clinical trials concerning the affected cellular pathways. This line of research begins to pave the way for personalized medicine approaches that are desperately needed for rare neurodegenerative diseases that are complex and heterogeneous.

AAV mediated carboxyl terminus of Hsp70 interacting protein overexpression mitigates the cognitive and pathological phenotypes of APP/PS1 mice

The E3 ubiquitin ligase,carboxyl terminus of heat shock protein 70(Hsp70)interacting protein(CHIP),also functions as a co-chaperone and plays a crucial role in the protein quality control system.In this study,we aimed to investigate the neuroprotective effect of overexpressed CHIP on Alzheimer’s disease.We used an adeno-associated virus vector that can cross the blood-brain barrier to mediate CHIP overexpression in APP/PS1 mouse brain.CHIP overexpression significantly ameliorated the performance of APP/PS1 mice in the Morris water maze and nest building tests,reduced amyloid-βplaques,and decreased the expression of both amyloid-βand phosphorylated tau.CHIP also alleviated the concentration of microglia and astrocytes around plaques.In APP/PS1 mice of a younger age,CHIP overexpression promoted an increase in ADAM10 expression and inhibitedβ-site APP cleaving enzyme 1,insulin degrading enzyme,and neprilysin expression.Levels of HSP70 and HSP40,which have functional relevance to CHIP,were also increased.Single nuclei transcriptome sequencing in the hippocampus of CHIP overexpressed mice showed that the lysosomal pathway and oligodendrocyte-related biological processes were up-regulated,which may also reflect a potential mechanism for the neuroprotective effect of CHIP.Our research shows that CHIP effectively reduces the behavior and pathological manifestations of APP/PS1 mice.Indeed,overexpression of CHIP could be a beneficial approach for the treatment of Alzheimer’s disease.

Liver as a new target organ in Alzheimer's disease:insight from cholesterol metabolism and its role in amyloid-beta clearance

Alzheimer's disease,the primary cause of dementia,is characterized by neuropathologies,such as amyloid plaques,synaptic and neuronal degeneration,and neurofibrillary tangles.Although amyloid plaques are the primary characteristic of Alzheimer's disease in the central nervous system and peripheral organs,targeting amyloid-beta clearance in the central nervous system has shown limited clinical efficacy in Alzheimer's disease treatment.Metabolic abnormalities are commonly observed in patients with Alzheimer's disease.The liver is the primary peripheral organ involved in amyloid-beta metabolism,playing a crucial role in the pathophysiology of Alzheimer's disease.Notably,impaired cholesterol metabolism in the liver may exacerbate the development of Alzheimer's disease.In this review,we explore the underlying causes of Alzheimer's disease and elucidate the role of the liver in amyloid-beta clearance and cholesterol metabolism.Furthermore,we propose that restoring normal cholesterol metabolism in the liver could represent a promising therapeutic strategy for addressing Alzheimer's disease.

Regulator of G protein signaling 6 mediates exercise-induced recovery of hippocampal neurogenesis,learning,and memory in a mouse model of Alzheimer’s disease

Hippocampal neuronal loss causes cognitive dysfunction in Alzheimer’s disease.Adult hippocampal neurogenesis is reduced in patients with Alzheimer’s disease.Exercise stimulates adult hippocampal neurogenesis in rodents and improves memory and slows cognitive decline in patients with Alzheimer’s disease.However,the molecular pathways for exercise-induced adult hippocampal neurogenesis and improved cognition in Alzheimer’s disease are poorly understood.Recently,regulator of G protein signaling 6(RGS6)was identified as the mediator of voluntary running-induced adult hippocampal neurogenesis in mice.Here,we generated novel RGS6fl/fl;APP_(SWE) mice and used retroviral approaches to examine the impact of RGS6 deletion from dentate gyrus neuronal progenitor cells on voluntary running-induced adult hippocampal neurogenesis and cognition in an amyloid-based Alzheimer’s disease mouse model.We found that voluntary running in APP_(SWE) mice restored their hippocampal cognitive impairments to that of control mice.This cognitive rescue was abolished by RGS6 deletion in dentate gyrus neuronal progenitor cells,which also abolished running-mediated increases in adult hippocampal neurogenesis.Adult hippocampal neurogenesis was reduced in sedentary APP_(SWE) mice versus control mice,with basal adult hippocampal neurogenesis reduced by RGS6 deletion in dentate gyrus neural precursor cells.RGS6 was expressed in neurons within the dentate gyrus of patients with Alzheimer’s disease with significant loss of these RGS6-expressing neurons.Thus,RGS6 mediated voluntary running-induced rescue of impaired cognition and adult hippocampal neurogenesis in APP_(SWE) mice,identifying RGS6 in dentate gyrus neural precursor cells as a possible therapeutic target in Alzheimer’s disease.

AAV-mediated expression of p65shRNA and bone morphogenetic protein 4 synergistically enhances chondrocyte regeneration

BACKGROUND:Adeno-associated virus(AAV)gene therapy has been proven to be reliable and safe for the treatment of osteoarthritis in recent years.However,given the complexity of osteoarthritis pathogenesis,single gene manipulation for the treatment of osteoarthritis may not produce satisfactory results.Previous studies have shown that nuclear factorκB could promote the inflammatory pathway in osteoarthritic chondrocytes,and bone morphogenetic protein 4(BMP4)could promote cartilage regeneration.OBJECTIVE:To test whether combined application of AAV-p65shRNA and AAV-BMP4 will yield the synergistic effect on chondrocytes regeneration and osteoarthritis treatment.METHODS:Viral particles containing AAV-p65-shRNA and AAV-BMP4 were prepared.Their efficacy in inhibiting inflammation in chondrocytes and promoting chondrogenesis was assessed in vitro and in vivo by transfecting AAV-p65-shRNA or AAV-BMP4 into cells.The experiments were divided into five groups:PBS group;osteoarthritis group;AAV-BMP4 group;AAV-p65shRNA group;and BMP4-p65shRNA 1:1 group.Samples were collected at 4,12,and 24 weeks postoperatively.Tissue staining,including safranin O and Alcian blue,was applied after collecting articular tissue.Then,the optimal ratio between the two types of transfected viral particles was further investigated to improve the chondrogenic potential of mixed cells in vivo.RESULTS AND CONCLUSION:The combined application of AAV-p65shRNA and AAV-BMP4 together showed a synergistic effect on cartilage regeneration and osteoarthritis treatment.Mixed cells transfected with AAV-p65shRNA and AAV-BMP4 at a 1:1 ratio produced the most extracellular matrix synthesis(P<0.05).In vivo results also revealed that the combination of the two viruses had the highest regenerative potential for osteoarthritic cartilage(P<0.05).In the present study,we also discovered that the combined therapy had the maximum effect when the two viruses were administered in equal proportions.Decreasing either p65shRNA or BMP4 transfected cells resulted in less collagen II synthesis.This implies that inhibiting inflammation by p65shRNA and promoting regeneration by BMP4 are equally important for osteoarthritis treatment.These findings provide a new strategy for the treatment of early osteoarthritis by simultaneously inhibiting cartilage inflammation and promoting cartilage repair.

The Value of CSF Level of β- amyloid Protein in the Diagnosis of Alzheimer's Disease

Objective:To evaluate the diagnostic potential of cerebrospmal fluid (CSF) levels of β-amyloid protein (Aβ) as biochemical marker for senile dementia in clinical practice. Methods : Sensitive enzyme-linked immunosorbent assay (ELISA) was performed in our lalxrratory to delect the CSF levels of Aβt-40, Aβ1-42 in 54 patients with Alzlteimer's disease (AD), and 30 normal controls (NC). Results: The cut off value of Aβ ratio and Aβ1-42 concentration in NC group provided 54. 51%, 90. 00% sensitivity and 81. 25%, 84. 38% specificity respectively in diagnosis of AD. Conclusion : AD group had a significant decreased level of Aβ1-42 and an increased level of Aβ ratio, compared with NC group.

Observation of amyloid precursor protein cleavage and Aβ generation in living cells by using multiphoton laser scanning microscopy

Objective To investigate the proteolytic mechanism of amyloid precursor protein （APP） and to explore amyloidbeta （Aβ） generation in living neurons. Methods DNA fragments were amplified by PCR or synthesized. The four fragments, CFP, 54bp, YFP and C99 were ligated into pcDNA3.0 vector to construct the recombinant plasmids pcDNA3.0-CFP-54bp- YFP and pcDNA3.0-CFP-54bp-YFP-C99. The SH-SY5Y cells were transiently transfected with pcDNA3.0-CFP-54bp-YFP or pcDNA3.0-CFP-54bp-YFP-C99. The expression of fusion gene was examined under a multiphoton laser scanning microscope. Fluorescence resonance energy transfer （FRET） was used to measure the β cleavage and γ cleavage of APE Aβ generation was confirmed by immunocytochemistry and multiphoton laser scanning microscopy. Cell viability was tested by MTT assay at different time points. Results （1） The double restriction endonuclease digestion and sequencing analysis confirmed the authenticity of the recombinant plasmids pcDNA3.0-CFP-54bp-YFP and pcDNA3.0-CFP-54bp- YFP-C99. （2） Blue and yellow fluorescences were detected in the transfected cells. （3） FRET occurred in pcDNA3.0-CFP- 54bp-YFP-transfected cells but not in pcDNA3.0-CFP-54bp-YFP-C99-transfected cells. （4） Aβ was produced in the pcDNA3.0- CFP-54bp-YFP-C99 transfected cells. （5） Aβ-deposition was widespread in the cell. （6） Cell viability decreased along with the intracellular Aβ deposition. Conclusion C99 is important for the APP β cleavage. Aβ may be generated and deposited in cells at the early stage of Alzheimer＇s disease. Intracellular Aβ accumulation brings deleterious effects on cells.

Effect of Panax notoginseng saponins on the expression of beta-amyloid protein in the cortex of the parietal lobe and hippocampus, and spatial learning and memory in a mouse model of senile dementia

BACKGROUND： The pharmacological actions of Panax notoginseng saponins （PNS） lie in removing free radicals, anti-inflammation and anti-oxygenation. It can also improve memory and behavior in rat models of Alzheimer＇s disease. OBJECTIVE： Using the Morris water maze, immunohistochemistry, real-time PCR and RT-PCR, this study aimed to measure improvement in spatial learning, memory, expression of amyloid precursor protein （App） and β -amyloid （A β ）, to investigate the mechanism of action of PNS in the treatment of AD in the senescence accelerated mouse-prone 8 （SAMP8） and compare the effects with huperzine A. DESIGN, TIME AND SETTING： A completely randomized grouping design, controlled animal experiment was performed in the Center for Research ＆ Development of New Drugs, Guangxi Traditional Chinese Medical University from July 2005 to April 2007. MATERIALS： Sixty male SAMP8 mice, aged 3 months, purchased from Tianjin Chinese Traditional Medical University of China, were divided into four groups： PNS high-dosage group, PNS low-dosage group, huperzine A group and control group. PNS was provided by Weihe Pharmaceutical Co., Ltd. （batch No.： Z53021485, Yuxi, Yunan Province, China）. Huperzine A was provided by Zhenyuan Pharmaceutical Co., Ltd. （batch No.： 20040801, Zhejiang, China）. METHODS： The high-dosage group and low-dosage group were treated with 93.50 and 23.38 mg/kg PNS respectively per day and the huperzine A group was treated with 0.038 6 mg/kg huperzine A per day, all by intragastric administration, for 8 consecutive weeks. The same volume of double distilled water was given to the control group. MAIN OUTCOME MEASURES： After drug administration, learning and memory abilities were assessed by place navigation and spatial probe tests. The recording indices consisted of escape latency （time-to-platform）, and the percentage of swimming time spent in each quadrant. The number of A β 1-40, A β 1-42 and App immunopositive neurons in the brains of SAMP8 mice was analyzed by immunohistochemistry. The mRNA content ofApp, tau, acetylcholinesterase, and synaptophysin （Syp） was tested by real time PCR and RT-PCR. RESULTS： The PCR results show that PNS can downregulate the expression of the App gene and upregulate the expression of the Syp gene in the parietal cortex and hippocampus of SAMP8 mice. The therapeutic effects of the PNS high-dosage group were greater than those of the PNS low-dosage group and the huperzine A group （P 〈 0.05）. The results of the Morris water maze and immunohistochemistry indicated that PNS can improve the capacity for spatial learning and memory in SAMP8 mice, and reduce the content of A β 1-40, A β 1-42 and expression of App in the brains of SAMP8 mice. The therapeutic effects of the PNS high-dosage group were greater than that of the PNS low-dosage group and the huperzine A group （P 〈 0.05）. CONCLUSION： These results support the hypothesis that PNS plays a therapeutic and protective role on the pathological lesions and learning dysfunction of Alzheimer＇s disease. The therapeutic effects of PNS for Alzheimer＇s disease are possibly achieved through downregulating the expression of the App gene and upregulating the expression of the Syp gene. The therapeutic effects of PNS are dose-dependent and are greater than the effect of huperzine A.