Exendin-4减轻Aβ1-42引起的大鼠工作记忆损伤

淀粉样β蛋白（amyloidβprotein,Aβ）在阿尔茨海默病（Alzheimer＇s disease,AD）的发生发展过程中起了关键作用[1],然而,目前仍缺乏拮抗Aβ的有效的治疗手段。近年来研究发现Exendin-4能减缓神经退行性疾病的发展过程,

六味地黄丸含药血清通过Caspase-1/GSDMD-N通路对Aβ_(1-42)诱导的SH-SY5Y细胞损伤的影响

目的通过对β-淀粉样蛋白1-42(Aβ_(1-42))诱导的人神经母细胞瘤细胞(SH-SY5Y细胞)损伤模型的研究,以Caspase-1/GSDMD-N为切入点,探讨六味地黄丸含药血清对SH-SY5Y细胞焦亡的影响。方法以终浓度为20μmol·L^(-1)Aβ_(1-42)诱导SH-SY5Y细胞建立细胞损伤模型。实验分为正常对照组、模型组和六味地黄丸含药血清组。采用台盼蓝染色法观察各组细胞形态并计算细胞成活率;采用酶联免疫吸附法检测细胞上清液中的白细胞介素1β(IL-1β)和白细胞介素18(IL-18)的含量。采用蛋白质印迹法检测细胞中Caspase-1和GSDMD-N的蛋白表达。结果与正常对照组相比,模型组细胞成活率显著降低(P<0.01),上清液中IL-1β和IL-18的含量显著增多(P<0.01),Caspase-1和GSDMD-N的蛋白表达显著升高(P<0.01);与模型组相比,含药血清组细胞成活率显著增高(P<0.01),上清液中IL-1β和IL-18的含量显著减少(P<0.01),Caspase-1和GSDMD-N的蛋白表达显著降低(P<0.01)。结论六味地黄丸含药血清可通过调节Caspase-1/GSDMD-N通路抑制细胞免疫炎性反应,进而抑制细胞焦亡,从而对损伤的SH-SY5Y细胞有保护作用。

吡格列酮对Aβ1-42引起的大鼠海马MAP激酶信号转导通路变化的影响

目的：研究PPAR-γ激动剂吡格列酮（pioglitazone，Pio）对淀粉样β蛋白（Amyloid-β protein，Aβ）1-42所致大鼠海马损伤的保护作用及其作用机制。方法：大鼠灌胃给予Pio（20、40、80mg·kg^-1-d^-1），正常对照组和Aβ1-42损伤组大鼠灌胃给予0．2％的二甲基亚砜（Dimethy1 Sulfoxide，DMSO），24h后，左侧脑室内单次注射Aβ1-42 5μL（2．0mmol／L）制备大鼠痴呆动物模型，

Hyperoside protects the blood-brain barrier from neurotoxicity of amyloid beta 1–42

Mounting evidence indicates that amyloid β protein（Aβ） exerts neurotoxicity by disrupting the blood-brain barrier（BBB） in Alzheimer＇s disease. Hyperoside has neuroprotective effects both in vitro and in vivo against Aβ. Our previous study found that hyperoside suppressed Aβ1-42-induced leakage of the BBB, however, the mechanism remains unclear. In this study, bEnd.3 cells were pretreated with 50, 200, or 500 μM hyperoside for 2 hours, and then exposed to Aβ1-42 for 24 hours. Cell viability was determined using 3-（4,5-dimethyl-2-thiazolyl）-2,5-diphenyl-2-H-tetrazolium bromide assay. Flow cytometry and terminal deoxynucleotidyl transferase-mediated d UTP nick-end labeling assay were used to analyze cell apoptosis. Western blot assay was carried out to analyze expression levels of Bax, Bcl-2, cytochrome c, caspase-3, caspse-8, caspase-9, caspase-12, occludin, claudin-5, zonula occludens-1, matrix metalloproteinase-2（MMP-2）, and MMP-9. Exposure to Aβ1-42 alone remarkably induced bEnd.3 cell apoptosis; increased ratios of cleaved caspase-9/caspase-9, Bax/Bcl-2, cleav ed caspase-8/caspase-8, and cleaved caspase-12/caspase-12; increased expression of cytochrome c and activity of caspase-3; diminished levels of zonula occludens-1, claudin-5, and occludin; and increased levels of MMP-2 and MMP-9. However, hyperoside pretreatment reversed these changes in a dose-dependent manner. Our findings confirm that hyperoside alleviates fibrillar Aβ1-42-induced BBB disruption, thus offering a feasible therapeutic application in Alzheimer＇s disease.

Geniposide, the component of the Chinese herbal formula Tongluojiunao, protects amyloid-β peptide(1–42)-mediated death of hippocampal neurons via the non-classical estrogen signaling pathway

Tongluojiunao （TLJN） is an herbal medicine consisting of two main components, geniposide and ginsenoside Rg1. TLJN has been shown to protect primary cultured hippocampal neurons. How-ever, its mechanism of action remains unclear. In the present study, primary cultured hippocampal neurons treated with Aβ1-42 （10 μmol/L） signiifcantly increased the release of lactate dehydroge-nase, which was markedly reduced by TLJN （2 μL/mL）, speciifcally by the component geniposide （26 μmol/L）, but not ginsenoside Rg1 （2.5 μmol/L）. hTe estrogen receptor inhibitor, ICI182780 （1 μmol/L）, did not block TLJN-or geniposide-mediated decrease of lactate dehydrogenase under Aβ1-42-exposed conditions. However, the phosphatidyl inositol 3-kinase or mitogen-activated protein kinase pathway inhibitor, LY294002 （50 μmol/L） or U0126 （10 μmol/L）, respectively blo cked the decrease of lactate dehydrogenase mediated by TLJN or geniposide. hTerefore, these results suggest that the non-classical estrogen pathway （i.e., phosphatidyl inositol 3-kinase or mitogen-activated protein kinase） is involved in the neuroprotective effect of TLJN, speciifcally its component, geniposide, against Aβ1-42-mediated cell death in primary cultured hippocampal neurons.

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.

T cells promote the regeneration of neural precursor cells in the hippocampus of Alzheimer's disease mice

Alzheimer＇s disease is closely associated with disorders of neurogenesis in the brain, and growing evidence supports the involvement of immunological mechanisms in the development of the disease. However, at present, the role of T cells in neuronal regeneration in the brain is unknown. We injected amyloid-beta 1-42 peptide into the hippocampus of six BALB/c wild-type mice and six BALB/c-nude mice with T-cell immunodeficiency to establish an animal model of Alzhei- mer＇s disease. A further six mice of each genotype were injected with same volume of normal saline. Immunohistochemistry revealed that the number of regenerated neural progenitor cells in the hippocampus of BALB/c wild-type mice was significantly higher than that in BALB/c-nude mice. Quantitative fluorescence PCR assay showed that the expression levels of peripheral T cell-associated cytokines （interleukin-2, interferon-y） and hippocampal microglia-related cyto- kines （interleukin-113, tumor necrosis factor-a） correlated with the number of regenerated neural progenitor cells in the hippocampus. These results indicate that T cells promote hippocampal neurogenesis in Alzheimer＇s disease and T-cell immunodeficiency restricts neuronal regeneration in the hippocampus. The mechanism underlying the promotion of neuronal regeneration by T cells is mediated by an increased expression of peripheral T cells and central microglial cytokines in Alzheimer＇s disease mice. Our findings provide an experimental basis for understanding the role of T cells in Alzheimer＇s disease.

Kallikrein-related peptidases 6 and 10 are elevated in cerebrospinal fluid of patients with Alzheimer’s disease and associated with CSF-TAU and FDG-PET

Background:Alterations in the expression of human kallikrein-related peptidases(KLKs)have been described in patients with Alzheimer’s disease(AD).We elucidated the suitability of KLK6,KLK8 and KLK10 to distinguish AD from NC and explored associations with established AD biomarkers.Methods:KLK levels in cerebrospinal fluid(CSF),as determined by ELISA,were compared between 32 AD patients stratified to A/T/(N)system with evidence for amyloid pathology and of 23 normal controls with normal AD biomarkers.Associations between KLK levels and clinical severity,CSF and positron emission tomography(PET)based AD biomarkers were tested for.Results:Levels of KLK6 and KLK10 were significantly increased in AD.KLK6 differed significantly between AD A+/T+/N+and AD A+/T−/N+or NC with an AUC of 0.922.CSF pTau and tTau levels were significantly associated with KLK6 in AD.Conclusions:KLK6 deserves further investigations as a potential biomarker of Tau pathology in AD.

Can blood amyloid levels be used as a biomarker for Alzheimer's disease?

Alzheimer’s disease(AD)increasingly affects society due to aging populations.Even at pre-clinical stages,earlier and accurate diagnoses are essential for optimal AD management and improved clinical outcomes.Biomarkers such as beta-amyloid(Aβ)or tau protein in cerebrospinal fluid(CSF)have been used as reliable markers to distinguish AD from non-AD,and predicting clinical outcomes,to attain these goals.However,given CSF access methods’invasiveness,these biomarkers are not used extensively in clinical settings.Blood Aβhas been proposed as an alternative biomarker since it is less invasive than CSF;however,sampling heterogeneity has limited its clinical applicability.In this review,we investigated blood Aβas a biomarker in AD and explored how Aβcan be facilitated as a viable biomarker for successful AD management.