Protective effects of proanthocyanidins on beta-amyloid peptide (25-35)-induced PC12 cell apoptosis by blocking S-phase and increasing p53 gene expression

BACKGROUND： Current studies related to the effects of proanthocyanidins on Alzheimer＇s disease have focused primarily on the signal transduction pathway of cellular apoptosis. However, the influence of p53 gene expression on cell cycle regulation, with regard to the protective mechanisms of proanthocyanidins, has not been reported. OBJECTIVE： To observe the effect of proanthocyanidins on cell cycle distribution, cellular apoptosis and p53 gene expression in β-amyloid peptide （25-35） （Aβ25-35）-induced PC12 cells cultured in serum-free media, and to investigate the molecular neuroprotective mechanisms of proanthocyanidins with regard to cell cycle regulation. DESIGN, TIME AND SETTING： A parallel, controlled, at the Institute of Biochemistry and Molecular Biology cellular, and molecular study was performed Guangdong Medical College from July 2006 to July 2008. MATERIALS： Proanthocyanidins were provided by Nanjing Xuezi Medical and Chemical Research Center, China; Aβ25-35 was provided by Sigma, USA; PC12 cells were provided by the Institute of Basic Medical Science, Academy of Military Medical Sciences; and rabbit anti-p53 polyclonal antibody was provided by Santa Cruz Biotechnology, USA. METHODS： PC12 cells were cultured in serum-free media for 24 hours. Cells from the model group were treated with 25 μmol/L Aβ25-35 for 24 hours. Cells in the drug protection group were pre-treated with 30 mg/L proanthocyanidins for 1 hour and then treated with 25 μmol/LAβ2^-35 for 24 hours. The control group was not treated. MAIN OUTCOME MEASURES： Flow cytometry was used to detect cell cycle distribution and rate of apoptosis; reverse-transcriptase polymerase chain reaction was used to detect p53 mRNA expression; and Western blot was used to detect p53 protein expression. RESULTS： After treating with 25 μmol/LAβ25-35 for 24 hours, the rate of apoptosis and the percentage of cells in S phase were significantly increased （P 〈 0.01 ）, and p53 mRNA and protein expressions were decreased. Pretreatment with proanthocyanidins for 1 hour blocked the increase in apoptosis and the percentage of cells in S phase in Aβ25-35-induced PC12 cells （P 〈 0.01 ） and increased p53 mRNA and protein expressions. CONCLUSION： Proanthocyanidins blocked apoptosis and S-phase arrest in Aβ25-35-induced PC12 cells cultured in serum-free media. The protective mechanism could be related to increased p53 mRNA and protein expressions.

Hydrogen sulfide inhibits beta-amyloid peptide-induced apoptosis in PC12 cells and the underlying mechanisms

BACKGROUND：Studies have demonstrated that hydrogen sulfide（H2S） levels are 55% lower in brains of Alzheimer＇s disease（AD） patients than in age-matched normal individuals,which suggests that H2S might be involved in some aspects of AD pathogenesis.OBJECTIVE：To observe the protective mechanisms of varied concentrations of H2S against β-amyloid-peptide（Aβ） induced apoptosis in pheochromoytoma（PC12） cells,and to analyze the pathway of action.DESIGN,TIME AND SETTING：A controlled,observational,in vitro experiment was performed at Neurophysiology Laboratory in Zhongshan Medical School,Sun Yat-sen University between July 2006 and May 2007.MATERIALS：PC12 cells were provided by the Animal Experimental Center of Medical School of Sun Yat-sen University.Glybenclamide,rhodamine123,and dihydrorhodamine123 were purchased from Sigma（USA）.METHODS：PC12 cells were incubated at 37 ℃ in a 5% CO2-enriched incubator with RPMI-1640 medium,supplemented with 5% horse-serum and 10% fetal bovine serum.Cells in logarithmic growth curves received different treatment：The PC12 cells were maintains at 37 ℃ with the original medium,then incubated in Aβ25-35,sodium hydrosulfide（NaHS）,glybenclamide,NaHS＋ Aβ25-35,or pretreated with glybenclamide 30 minutes prior to administration of and Aβ25-35,respectively.MAIN OUTCOME MEASURES：（1） The survival rate of PC12 cells was detected by MTT assay and Hoechst staining.（2） The apoptosis rate of PC12 cells was detected utilizing flow cytometry with propidium iodide staining,and morphological changes of apoptotic cells were observed.（3） The mitochondrial membrane potential was detected by Rhodamine123-combined flow cytometry.（4） The intracellular reactive oxygen species content was detected by dihydrorhodamine123-combined flow cytometry.RESULTS：Aβ25-35 induced significantly decreased viability and increased percentage of apoptosis in PC12 cells,as well as dissipated mitochondrial membrane potential expression and an overproduction of reactive oxygen species.When PC12 cells were co-treated with NaHS and Aβ25-35,the decreased cell viability induced by 20 μmol/L Aβ25-35 was concentration-dependently blocked by NaHS（50,100,and 200 μmol/L）.NaHS（100 μmol/L） obviously reduced the percentage of apoptotic PC12 cells induced by 20 μmol/L Aβ25-35.In addition,100 μmol/L NaHS inhibited mitochondrial membrane potential dissipation and reactive oxygen species overproduction.When the ATP-sensitive K channel（KATP） inhibitor,glybenclamide,was administered 30 minutes prior to NaHS and Aβ25-35 treatment,the NaHS-dependent cellular protection was partly blocked.This resulted in reduced PC12 cell viability and increased the percentage of apoptosis,as well as significantly blocked mitochondrial membrane potential preservation and inhibited reactive oxygen species overproduction due to NaHS treatment.CONCLUSION：NaHS protected PC12 cells against Aβ25-35-induced damage.NaHS-dependent cellular protection was associated with mitochondrial membrane potential preservation and inhibition of reactive oxygen species overproduction.The KATP channel inhibitor,glybenclamide,significantly blocked the cellular protective effects of NaHS,indicating that KATP channel activation plays an important role in NaHS-induced protection of PC12 cells to Aβ25-35-induced damage.

Multifaceted neuroprotective effects of(-)-epigallocatechin-3-gallate(EGCG)in Alzheimer's disease:an overview of pre-clinical studies focused onβ-amyloid peptide

Alzheimer’s disease(AD)is the most common neurodegenerative disease characterized by cognitive decline and memory impairment.Many lines of evidence indicate that excessiveβ-amyloid peptide(Aβ)generation and aggregation play pivotal roles in the initiation of AD,leading to various biochemical alteration including oxidative damage,mitochondrial dysfunction,neuroinflammation,signaling pathway and finally resulting in neuronal death.AD has a complex pathogenic mechanism,and a single-target approach for anti-AD strategy is thus full of challenges.To overcome these limitations,the present study focused to review on one of multiple target-compounds,(-)-epigallocatechin-3-gallate(EGCG)for the prevention and treatment of AD.EGCG is a main bioactive polyphenol in green tea and has been reported to exert potent neuroprotective properties in a wide array of both cellular and animal models in AD.This review demonstrated multiple neuroprotective efficacies of EGCG by focusing on the involvement of Aβ-evoked damage and its Aβregulation.Furthermore,to understand its mechanism of action on the brain,the permeability of the blood-brain barrier was also discussed.

Effects of Yizhi Capsule (益智胶囊) on Learning and Memory Disorder and β-amyloid Peptide Induced Neurotoxicity in Rats

To explore the effects of Yizhi Capsule （益智胶囊, YZC） on learning and memory disorder and β-amyloid peptide induced neurotoxicity in rats. Methods： Various doses of YZC were administered to Sprague-Dawley （SD） rats for 8 consecutive days, twice a day. On the 8th day of the experiment, scopolamine hydrobromide was intraperitoneally injected to every rat and Morris water maze test and shuttle dark avoidance test were carried out respectively to explore the changes of learning and memory capacities in the rats. Resides, after the cerebral cortical neurons of newborn SD rats aged within 3 days were cultured in vitro for 7 days, drug serum containing YZC was added to the cultured neurons before or after β amyloid peptide25-35 （Aβ25-35） intoxication to observe the protective effect of YZC on neurotoxicity by MTT assay and to determine the LDH content in the supernatant. Results： Compared with those untreated with YZC, the rats having received YZC treatment got superiority in shorter time of platform seeking in Morris water maze test, as well as elongated latent period and less times of error in shuttle dark avoidance test. On the cultured neurons, YZC drug serum could effectively increase the survival rate of Aβ25-35 intoxicated neurons and reduce the LDH contents in cultured supernatant. Conclusion： YZC has an action of improving learning and memory disorder, and good protective effect on Aβ25-35 induced neurotoxicity in SD rats. KEY WORDS

STUDY ON THE THERAPEUTIC EFFECTS OF GINSENOSIDE Rg-1 AND GASTRODINE ON AD MODEL RATS INDUCED BY β-AMYLOID PEPTIDE (25-35)

Objective To study the therapeutic effects of Ginsenoside Rg-1 and Gastrodine on rats model of Alzheimer's disease(AD). Methods Aggregated β-Amyloid peptide (25-35) was injected into the lateral ventricle of rats to establish AD models. Ginsenoside Rg-1, Gastrodine and Ginsenoside Rg-1+Gastrodine were intraperitoneally injected into rats of each test group(Ginsenoside Rg-1∶10mg/kg·day; Gastrodine 100mg/kg·day) for 4 weeks, the rats of control group received equal volume of saline. Passive avoidance task and Morris maze test were done to assess the ability of learning and memory. The content of superoxide dismutase (SOD), malondiadehyde (MDA), total-antioxidative capability (T-AOC), Choline acetyltransferase (ChAT) and acetylcholinesterase (AchE) in brain tissue were measured. Results Ginsenoside Rg-1 and Gastrodine significantly improved learning and memory deficits in the rats with AD induced by β-Amyloid peptide (25-35) (P<0.05). Ginsenoside Rg-1+Gastrodine group were better than Ginsenoside Rg-1 group and Gastrodine group (P<0.05). Ginsenoside Rg-1 reduced the increase of SOD, MDA, but inhibited the decrease of T-AOC, AchE and ChAT; Gastrodine reduced the increase of SOD, MDA, while inhibited the decrease of T-AOC. Gastrodine could also prevent the activity of ChAT and AchE decline in AD rats. Conclusion Both Ginsenoside Rg-1 and Gastrodine have therapeutic effects on rats with AD; Ginsenoside Rg-1 and Gastrodine injection at the same time were better than only using one of them. Their mechanisms might different. Ginsenoside Rg-1 can not only inhibit peroxidation but also increase the activity of AchE and ChAT in brain tissue, while Gastrodine can inhibit peroxidation only, but it can't prevent the decline of ChAT and AchE activity in AD rats.

Prediction of fibril formation by early-stage amyloid peptide aggregation

Amyloid fibrils are found in systemic amyloidosis diseases such as Alzheimer's disease,Parkinson's disease,and type II diabetes.Currently,these diseases are diagnosed by observation of fibrils or plaques,which is an ineffective method for early diagnosis and treatment of disease.The goal of this study was to develop a simple and quick method to predict the possibility and speed of fibril formation before its occurrence.Oligomers generated from seven representative peptide segments were first isolated and detected by ion-mobility mass spectrometry(IM-MS).Then,their assemblies were disrupted using formic acid(FA).Interestingly,oligomers that showed small ion intensity changes upon FA addition had rapid fibril formation.By contrast,oligomers that had large ion intensity changes generated fibrils slowly.Two control peptides(aggregation/no fibrils and no aggregation/no fibrils)did not show changes in their ion intensities,which confirmed the ability of this method to predict amyloid formation.In summary,the developed method correlated MS intensity ratio changes of peptide oligomers on FA addition with their amyloid propensities.This method will be useful for monitoring peptide/protein aggregation behavior and essential for their mechanism studies.

Brain-derived neurotrophic factor prevents beta-amyloid-induced apoptosis of pheochromocytoma cells by regulating Bax/Bcl-2 expression

Brain-derived neurotrophic factor was utilized in the present study to treat cell injury models induced by aggregated β-amyloid（25 35）. Methylthiazolyldiphenyl-tetrazolium bromide assay and western blot analysis showed that brain-derived neurotrophic factor provided neuroprotection against cellular apoptosis by suppressing the decline in β-amyloid（25 35）-induced cell activity and the increasing ratio of Bax/Bcl-2. After treating pheochromocytoma cells with tyrosine kinase receptor B receptor inhibitor K252a, brain-derived neurotrophic factor reverses the above- mentioned changes. The experimental findings suggested that brain-derived neurotrophic factor prevented β-amyloid peptide-induced cellular apoptosis by modulating Bax/Bcl-2 expression, and this effect was associated with binding to the specific tyrosine kinase receptor B receptor.

<i>Ratanasampil</i>(Tibetan Medicine, RNSP) Reduces <i>β</i>-Amyloid Protein (Aβ) and Pro-Inflammatory Factor Levels and Improves Cognitive Functions in Mild-to-Moderate Alzheimer’s Disease (AD) Patients Living at High Altitude

Ratanasampil (RNSP) is a traditional Tibetan medicine used for the treatment of stroke and cerebrovascular diseases. Previous discoveries that RNSP can reduce β-amyloid protein levels and increase learning and memory in Alzheimer’s mouse models (Tg2576) led us to investigate whether RNSP can improve cognitive functions in Alzheimer’s patients. In this study, 146 AD patients living in Qinghai province received either one gram or 0.33 gram daily of RNSP for 16 weeks. Placebo patients received Piracetam. Serum Aβ40 and Aβ42 levels were measured at the beginning of the study and after 4 and 16 weeks of treatment. Compared to the same group before treatment, MMSE scores, ADAS-cog scores and ADL scores were significantly improved (p 0.05, p > 0.05). After 16-week treatment, serum TNF-α, IL-1β, IL-6 and Aβ42 levels were significantly decreased (p < 0. 01) in the high-dose RNSP group, whereas no significant differences were found in the low-dose and placebo groups. The Aβ42/Aβ40 ratio was significantly decreased after 4-week and 16-week treatment in the high-dose RNSP group (p < 0. 05, p < 0.01). Furthermore, serum Aβ42 concentrations had a strong positive correlation with TNF-α, IL-1β and IL-6 levels. There were no observable adverse effects in either treatment or control groups. We conclude that further clinical trials of RNSP in Alzheimer disease are warranted.

Cystine oligomers successfully attached to peptide cysteine- rich fibrils

Amyloid peptides are renowned to be related to neurodegenerative diseases, however, a fruitful avenue is to employ them as high-performance nanomaterials. These materials benefit from the intrinsic outstanding mechanical robustness of the amyloid backbone made of r-strands. In this work, we exploited amyloid-like fibrils as functional material to attach pristine L-cysteine aggregates （cystine oligomers） and gold nanoparticles, without the need of templating compounds. This work will open new avenues on functional materials design and their realisation.

Specific humoral immune responses in rhesus monkeys vaccinated with the Alzheimer’s disease-associated β-amyloid 1-15 peptide vaccine

Background Alzheimer’s disease(AD) is a neurodegenerative disorder characterized by overproduction of β-amyloid (Aβ), with the subsequent pathologic deposition of Aβ which is important for memory and cognition. Recent studies showed murine models of AD and AD patients inoculated with Aβ 1-42 peptide vaccine had a halted or delayed pathological progression of AD. Unfortunately, the clinical phase Ⅱ a trial of Aβ 1-42 peptide vaccine (AN1792) was halted prematurely because of episodes of menigoencephalitis in 18 of the vaccinated patients. The vaccination of BALB/c or Tg2576 transgenic mouse with Aβ 1-15 peptide vaccine is safe and the immune effects are satisfactory. This study further characterizes the specific humoral immune responses in adult rhesus monkeys induced by Aβ 1-15 peptide vaccine.Methods Five male adult rhesus monkeys were injected intramuscularly with Aβ 1-15 peptide vaccine at baseline and at weeks 2, 6, 10, 14, 18 and 22. The titers and IgG isotypes of the antibody against Aβ 1-42 in serum was measured by Enzyme-linked Immunosorbent Assay (ELISA). The specificity of the antibody against Aβ 1-42 was determined by Western blot. The Aβ plaques in Tg2576 transgenic mouse brain were stained with the antiserum using immunohistochemistry method.Results At the eighth week after the vaccination, antibody against Aβ 1-42 began to develop significantly in serum. The titers of the antibody increased following vaccine boosted and reached 1∶3840 at the twenty-fourth week, then decreased after the termination of inoculation. The IgG1 was accounted for the highest level in the antiserum pool. The antibody against Aβ 1-42 showed high specificity. The Aβ plaques in Tg2576 transgenic mouse brain were labeled with the antiserum.Conclusion Aβ 1-15 vaccine can induce vigorously specific humoral immune responses in adult rhesus monkey.

Cholesterol Depletion Reduces the Internalization of β-Amyloid Peptide in SH-SY5Y Cells

Deposition of amyloid in the brain is a critical step in the pathogenesis of Alzheimer＇s disease. The endocytosis of β-amyloid peptide （Aβ） is an important factor among the many factors that contribute to the genesis of amyloid deposits. Since cholesterol participates in many important physiological processes, the present work investigated the relationship between the cellular cholesterol content and the endocytosis of the exogenic Aβ, and found that reduction of the cholesterol content by methyl-β-cyclodextrin could reduce the endocytosis of AI3. The study indicates that the endocytosis of Aβ is partly mediated by cholesterol.

PGN对BV2细胞内吞Aβ寡聚体的影响

目的探讨前炎介质肽聚糖(peptidoglycan,PGN)对BV2细胞内吞β淀粉样蛋白1-42(amyloid proteinβ,Aβ1-42)寡聚体的影响及其机制。方法采用细胞株传代法培养BV2细胞,分别替代小胶质细胞;按Klein WL(2002)方法制备Aβ1-42寡聚体;采用免疫荧光染色鉴定BV2细胞内吞Aβ的量;Western blotting方法检测各组BV2细胞磷酸化p38丝裂原活化蛋白激酶(phosphorylated p38 mitogen-activated protein kinase,p38MAPK)、p38MAPK蛋白表达情况;PCR方法检测各组BV2细胞鼠同系物甲酰肽受体(mouse homologue formyl peptide receptor 2,mFPR2)mRNA。结果 PGN激活BV2细胞内吞Aβ1-42寡聚体增多,可被mFPR2拮抗剂抑制;PGN可引起BV2细胞表达mFPR2 mRNA增多,且存在浓度、时间相关性,可被SB202190-p38MAPK抑制剂抑制,且随着SB202190浓度增加,抑制程度增加,各组浓度与0μmol/L相比,抑制明显差异有统计学意义,1μmol/L组P<0.05,10、20、30μmol/L组均P<0.01;PGN作用BV2细胞后各时间点p38MAPK的磷酸化激活程度同对照组相比差异有统计学意义(P<0.01)。结论 PGN可激活BV2细胞内吞Aβ增多,此过程可被mFPR2拮抗剂阻断,推测BV2细胞内吞Aβ可能与mFPR2表达有关;PGN可引起BV2细胞的表达mFPR2 mRNA增多,可能参与激活BV2细胞内吞Aβ的作用;PGN可引起BV2细胞p38MAPK表达量增多,且其抑制剂抑制mFPR2 mRNA表达,可能为激活BV2细胞内吞Aβ的作用机制。

国产β-淀粉样蛋白聚合寡聚体的方法及效果初探

目的探讨国产人源性β-淀粉样蛋白(Aβ)聚合寡聚体的方法及其聚合效果。方法 Aβ40、Aβ42室温条件分别溶解于纯度≥99.0%的六氟异丙醇中,使Aβ浓度至1 mmol/L、20 min;高纯氮处理使六氟异丙醇完全挥发后,添加纯度≥99.5%的二甲基亚砜,使Aβ浓度至6 mmol/L,30℃水浴超声10 min;添加含0.05%十二烷基硫酸钠的磷酸盐缓冲液(0.02 mol/L,p H7.4),Aβ浓度至120μmol/L;再用上述缓冲液分别稀释Aβ至40、80μmol/L,形成3种浓度梯度。37℃恒温摇床100 r/pmin行聚合反应2、12、24、48、72、96和120 h;SDS-PAGE,银染处理,分别考察上述条件的聚合效果。结果 3种浓度的Aβ40寡聚体聚合效果有很大差异:40μmol/L聚合48、120 h,80μmol/L聚合12 h有较明显的二十二聚体出现,120μmol/L聚合≥12 h,有四聚体至十聚体形成。但3种浓度Aβ40形成寡聚体又有一定相似性:均有大量的单体、二聚体、三聚体存在,随着聚合时间延长,寡聚体总量及高分子量寡聚体形成量并未明显增加。3种浓度的Aβ42聚合效果有明显区别:随着聚合浓度升高,十二聚体、二十一聚体的形成量逐渐下降,相同聚合时间内,随着浓度的升高,四聚体至十聚体形成量逐渐增加;但3种浓度的Aβ42聚合也有相似处:均存在大量的单体、二聚体、三聚体,随着聚合时间的延长,四聚体至十聚体形成量有增加趋势,此与Aβ40聚合效果有明显差异。结论采用常用的方法均能使国产Aβ40、Aβ42形成寡聚体;总体来讲,相对于聚合时间,聚合浓度对形成高分子量的Aβ寡聚体种类影响较大。

β-淀粉样蛋白与膜脂作用后的交联研究

β淀粉样蛋白(Aβ)与细胞膜相互作用形成寡聚体存在于膜脂内,聚丙烯酰胺凝胶电泳常用于分析这些膜内寡聚体的结构和状态,但十二烷基硫酸钠(SDS)使得寡聚体原有的结构极易被破坏,使用合适的交联剂来稳定蛋白在膜上的状态,从而获取寡聚体本身的结构.用双琥珀酰亚胺辛二酸酯磺酸钠盐(BS3)对Aβ42进行交联,将BS3与戊二醛交联进行比较分析,通过电泳、脂质体技术,并采用电镜照片对照分析.实验结果显示:1)BS3交联后的样品能保持蛋白原先的状态;2)BS3不会导致蛋白过度交联,很适合作为分析膜脂与β淀粉样蛋白相互作用的交联剂.因此,报道了BS3分析β淀粉样蛋白这种易聚集蛋白在插膜后的结构,且BS3可以替代戊二醛成为更有效的交联剂,这将为β淀粉样蛋白及其他易聚集蛋白插膜提供很好的研究方法.

AβOs对大鼠原代海马神经细胞丝裂原活化蛋白激酶信号转导通路的影响

目的:观察β-淀粉样蛋白寡聚体(AβOs)对原代培养大鼠海马神经细胞丝裂原活化蛋白激酶(MAPK)信号转导通路的影响。方法:原代培养大鼠海马神经细胞,用免疫荧光染色鉴定纯度,制备并鉴定AβOs,用不同浓度AβOs(0.25、0.5、1及10μmol/L)处理细胞48 h,采用CCK-8试验检测细胞的存活率,蛋白印迹法(Western blotting)检测细胞中细胞外信号调节蛋白激酶(ERK)、c-Jun氨基末端激酶(JNK)及p38磷酸化及总蛋白表达水平。结果:免疫荧光染色结果显示原代大鼠海马神经细胞的体外培养纯度达85%以上;低于0.5μmol/L AβOs对原代神经细胞无明显毒性作用,但可见phospho-ERK1/2和phospho-JNK蛋白表达升高;1μmol/L及更高浓度的AβOs对原代神经细胞有细胞毒性作用,同时可引起phospho-ERK1/2和phospho-JNK蛋白表达水平均降低,但总ERK1/2及总JNK蛋白表达水平未受明显影响,而phospho-p38及总p38蛋白表达水平与AβOs作用浓度呈负相关。结论:AβOs与MAPK信号通路之间的作用可因AβOs的作用浓度不同而出现差异。

BS^3交联分析β淀粉样蛋白的寡聚结构

使用交联剂双琥珀酰亚胺辛二酸酯磺酸钠盐(Bis(sulfosuccinimidyl),BS3)对Aβ1-42进行交联,通过与之前报道的戊二醛交联进行比较分析,可以看出BS3更适合分析蛋白的寡聚状态,这将为Aβ蛋白及类似的易聚集蛋白在体内、外研究提供很好的参考。

FZS中药合剂对细胞凋亡的保护作用研究

目的探讨FZS中药合剂对Aβ25-35、Aβ42、Aβ42寡聚体诱导的PC12细胞凋亡的保护作用。方法应用正常细胞进行对照研究,通过测定MTT、LDH和原位末端标记(TUNEL)方法检测细胞凋亡。原子力显微镜观察PC12细胞表面突起的变化。结果MTT在FZS组明显增高(P<0.05);LDH、TUNEL凋亡率在FZS组表达明显降低(P<0.05);原子力显微镜观察Aβ致细胞表面突起缩短的现象在FZS组明显改善,差异有显著意义(P<0.05)。结论FZS可以通过降低Aβ的细胞凋亡作用而减少其细胞毒性,FZS中药合剂可能成为Alzheimer病的治疗手段之一。

艾塞那肽-4改善β淀粉样蛋白诱导的小鼠昼夜节律紊乱及时钟蛋白CLOCK蛋白的异常表达

目的探讨艾塞那肽(exendin)-4对β淀粉样蛋白(Aβ)引起的C57BL/6小鼠昼夜节律紊乱的影响,观察exendin-4对Aβ引起的海马时钟蛋白CLOCK蛋白异常表达的影响。方法海马内注射15 nmol Aβ31-35、50 pmol Exendin-4,对照组海马内注射等体积的高压三蒸水,利用Vital View跑轮分析软件观察各实验组小鼠昼夜节律的变化。蛋白质印迹法检测各组小鼠海马区CLOCK蛋白在不同时间的表达变化。结果 Aβ处理组小鼠出现明显昼夜节律紊乱,其自由运转周期为(23.67±0.05)h,鲁棒值为(22.5±4.3)%,与对照组比较差异有统计学意义(P<0.05),Exendin-4预处理组小鼠昼夜节律部分恢复正常,其自由运转周期为(23.53±0.05)h,鲁棒值为(47.0±4.0)%,与Aβ处理组比较差异有统计学意义(P<0.05)。蛋白质印迹法结果显示,对照组CLOCK蛋白在CT8和CT20表达高,在CT2和CT14时表达低,Aβ处理组CLOCK蛋白表达缺乏节律性,Exendin-4预处理组CLOCK蛋白部分恢复节律表达。结论 Exendin-4可部分恢复Aβ31-35导致的C57BL/6小鼠的昼夜节律紊乱,并部分纠正Aβ31-35引起的海马区CLOCK蛋白的异常表达。

β淀粉样肽在阿尔茨海默症发病中的分子机制

作为老年性痴呆的主要类型,阿尔茨海默症(AD)的病理特征包括大脑局部,尤其是海马和皮层神经元退行性变化,细胞内神经原纤维缠结和细胞外老年斑沉淀,其中老年斑的主要毒性成分为β-淀粉样肽(Aβ).随着对AD研究的深入,关于疾病发生的Aβ假说得到了深入的发展,越来越多的证据显示Aβ可能是AD发生的原发性病理因子.Aβ假说认为,AD是一种由于基因缺陷直接或间接改变淀粉样前蛋白(APP)表达或蛋白酶解过程,从而影响Aβ聚集稳定性的病理综合征,Aβ产生和清除之间的平衡逐渐改变,聚集态的Aβ累积引发连串的复杂反应,包括突触/突起的变化,Tau蛋白磷酸化,递质丢失,神经胶质增生和炎症反应等,最终出现神经元功能失调,死亡,斑块形成,神经原纤维缠积等病理现象.但Aβ究竟是通过什么样的分子途径引发AD的,Aβ作用的部位在哪里,Aβ毒性与其聚集状态的关系等等问题都还未能完全揭示.结合近年来实验室的研究结果和体会,综述了Aβ最新的研究进展.

洛伐他汀对抗AβOs引起的SH-SY5Y细胞毒性作用

目的:观察洛伐他汀对抗Aβ寡聚体(AβOs)引起的SH-SY5Y细胞毒性作用。方法:生长至80%~90%并用无血清培养基培养12 h的SH-SY5Y细胞分为对照组、洛伐他汀处理组(0.1μmol/L洛伐他汀处理24 h)、AβOs处理组(0.5μmol/L AβOs处理48 h)和洛伐他汀加AβOs处理组(0.1μmol/L洛伐他汀处理24 h,再加入0.5μmol/L AβOs继续处理48 h),采用CCK-8法检测各组细胞活性,使用相应的试剂盒检测细胞超氧化物歧化酶(SOD)及谷胱甘肽过氧化物酶(GSH-Px)活性、丙二醛(MDA)含量。结果:0.5μmol/L AβOs处理SHSY5Y细胞48 h后,与对照组相比,SH-SY5Y细胞活性、SOD及GSH-Px活性显著降低,MDA含量明显增加(P<0.05);在0.5μmol/L AβOs处理SH-SY5Y细胞前,预先用0.1μmol/L洛伐他汀处理细胞24 h,可减弱AβOs引起的细胞活性、SOD和GSH-Px活性及MDA含量的改变(P<0.05)。结论:洛伐他汀可对抗AβOs引起的SHSY5Y细胞毒性作用,其保护机制可能与抑制氧化应激有关。