Le précurseur de la protéine amyloïde (APP) est une protéine transmembranaire qui, après coupure séquentielle par les sécrétases β et γ, produit des peptides Aβ trouvés dans les plaques séniles de patientsatteints d’Alzheimer. Par contre, la forme soluble de l’APP (sAPPα), produite après coupure par une sécrétase α, augmente la survie cellulaire, la croissance des neurites et la synaptogénèse. L’APP est coupéeau site α par 3 métalloprotéases : ADAM9, ADAM10 et ADAM17.Notre laboratoire a montré que la stimulation du récepteur purinergique P2X7 (P2X7R) provoque la coupure protéolytique du précurseur de la protéine amyloïde (APP). Le Dr Delarasse a établi que la voie non amyloïdogénique est mise en jeu et que c'est le fragment sAPPα, neuroprotecteur, qui est produit. Deplus, le laboratoire a précédemment démontré que ce ne sont pas les alpha-sécrétases ADAM9, 10 et 17 qui sont responsables du clivage protéolytique de l'APP après stimulation du P2X7R dans les cellules de neuroblastome Neuro2a.Durant mes travaux de thèse, nous avons étudié la voie biochimique menant à la libération du fragments APPα. L’activation du P2X7R stimule la phosphorylation et la translocation rapide à la membrane plasmique de protéines, appelées ezrine, radixine et moesine (ERM) qui ont la capacité d’établir un lien entre la région cytosolique du P2X7R et la F-actine. Les ERM jouent un rôle crucial dans la coupure protéolytique de l’APP par les métalloprotéases ADAM. En effet, l’inhibition de l’expression des ERM par RNA interférence aboutit à une absence de coupure de l’APP. Par ailleurs, nous avons observé que les MAPKERK1/2 et JNK et la ROCKinase sont nécessaires à la phosphorylation activatrice des ERM et jouent donc un rôle en amont des ERM. Enfin, nous avons mis en évidence le rôle de la PI3K en aval des ERM.Par ailleurs, nous avons démontré que l’activation du récepteur purinergique P2X7 entraînait la coupure protéolytique de la molécule NrCAM par ADAM17 aboutissant à la libération du fragment soluble del’ectodomaine de NrCAM. Les résultats obtenus indiquent que la coupure de NrCAM est dépendante de l’activation et de la fixation des ERM à NrCAM. Ces résultats suggèrent fortement que les ERM sont indispensables à la coupure protéolytique de différents substrats après stimulation du P2X7R.Les données obtenues mettent en évidence un mécanisme moléculaire original et important qui fait jouer aux ERM un rôle central de « liens moléculaires » dans le clivage protéolytique des protéines transmembranaires. A ce stade de notre étude, nous émettons l’hypothèse que les ERM agissent en aval du récepteur P2X7, en liant les substrats et/ou les protéases qu’ils regroupent à la membrane plasmique favorisant ainsi le clivage des substrats. / The amyloid protein precursor (APP) can be cleaved in neural cells by α-secretases to produce the soluble APP ectodomain (sAPPα), which is neuroprotective. We have shown previously that activation of the purinergic receptor P2X7 (P2X7R), a member of the P2X receptor family of ATP-gated cation channels, triggers sAPPα shedding from neural cells. Here, we demonstrate that theactivation of Ezrin/Radixin/Moesin proteins (ERM) is required for the P2X7R-dependent proteolyticprocessing of APP leading to sAPPα release. Indeed, the down regulation of ERM by siRNA blocksthe P2X7R-dependent shedding of sAPPα. We also show that P2X7R stimulation triggers thephosphorylation of ERM. Thus, ezrin translocates to the plasma membrane to interact with P2X7R.Using specific pharmacological inhibitors, we have established the order in which several enzymestrigger the P2X7R-dependent release of sAPPα. Thus, a Rho-kinase and the MAPK modules ERK1/2and JNK act upstream of ERM while a PI3Kinase activity is triggered downstream. This work for the first time identifies ERM as major partners in the regulated non-amyloidogenic processing of APP. Inaddition, we have recently established that the stimulation of P2X7R leads to the proteolytic cleavage of NrCAM by ADAM17 and the shedding of the soluble extracellular domain of NrCAM. Our results clearly show that the proteolytic cleavage of NrCAM is dependant of ERM activation and fixation tothe intracellular region of NrCAM. Thus, our results strongly suggest that ERM are required for the proteolytic cleavage of numerous substrates after P2X7R stimulation. Our findings suggest that ERM play a central role in the proteolytic cleavage of transmembrane proteins and act as molecular linkswhich aggregate ADAMs and substrates at the plasma membrane promoting the cleavage of substrates.

As demências Frontotemporais (DFT) compreendem 2 fenótipos clínicos: distúrbios comportamentais ou de linguagem. Coletivamente, as DFT podem ser causadas por um grupo diversas de doenças neurodegenerativas chamadas degeneração lobar frontotemporal (DLFT). Novas entidades têm sido descritas neste grupo e o conceito está em constante evolução. Parte dos mecanismos envolvidos na morte celular nas DLFTs também são observados n envelhecimento normal. Determinar as entidades e freqüência das DLFTs em uma série com utilização de imunoistoquímica. Uma série prospectiva de 833 casos avaliados prospectivamente no Centro de Pesquisas de Doença de Alzheimer da Washington University - EUA. Os casos de DFT foram selecionados por critérios clínicos e a classificação neuropatológica foi baseada em protocolos universalmente aceitos para DLFT. Dos casos de demência, 53(6,3%) atenderam aos critérios clínicos e neuropatológicos para DLFT. Outros 8 casos atenderam apenas aos critérios clínicos de DFT. As tauopatias representaram 40% dos casos. Entretanto, a maioria dos casos apresentava inclusões ubiquitina-positivas e tau-negativas. Esclerose hipocampal e alterações do tipo Doença de Alzheimer foram encontradas em 12 e 10 casos, respectivamente. Apesar da DLFT-U ter sido a entidade mais freqüente nesta série, entidades e menos comuns não incluídas nas recomendações de McKhann também podem apresentar fenótipo clínico de DFT. A inclusão destas novas entidades é mais uma evidência de que os sintomas clínicos são mais dependentes das áreas acometidas do que da entidade em si. A melhor compreensão desses mecanismos tem um grande potencial em auxiliar no desenvolvimento de medidas que possam modular ou retardar os efeitos do envelhecimento no cérebro, além é claro de trazer possibilidade de tratamento, hoje inexistente, para os pacientes acometidos. / Frontotemporal dementia (FTD) encompasses two clinical phenotypes: progressive behavioral change and language disorder. Collectively, FTD may be caused by a diverse group of neurodegenerative diseases called frontotemporal lobar degenerations (FTLDs). New entities have been described and the nosology of FTLDs continues to evolve. To determine the type and frequency of FTLDs in a series using contemporary immunohistochemical methods. Eight hundred and thirtythree dementia cases were prospectively assessed at Washington University Alzheimer Disease Research Center (WUADRC) and cases with clinical FTD were identified using existing diagnostic criteria and neuropathologic entities were ascertained using immunohistochemistry and contemporary diagnostic criteria. Of the dementia cases, 53(6.3%) met clinical criteria for FTD; 45(5.1%) fulfilled both clinical and neuropathological criteria for FTLD, and another 8 fulfilled only the clinical criteria. Forty percent of the cases were tauopathies. However, most FTLD cases were characterized by ubiquitin-positive, tau-negative inclusions. Co-existing hippocampal sclerosis and AD-type changes were observed in 12 and 10 cases, respectively. Although FTLD-MND-type is the most frequent FTLD in this prospectively assessed series, less common entities not included in the McKhann criteria, may also present clinically as FTD and should be considered as part of the neuropathologic spectrum of FTLDs that may be encountered in the dementia clinic. The better understanding of the cell death mechanisms related to those entities is likely to contribute for the development of a treatment for FTLD as well for a way of modulate brain aging.

A doença de Alzheimer (DA) é caracterizada por declínio cognitivo e funcional progressivo e constitui-se como a forma mais prevalente de demência. O diagnóstico da DA é realizado atualmente, exclusivamente por meio de critérios clínicos. No entanto, a manifestação clínica da DA é precedida por um longo período assintomático, com depósito silencioso das proteínas tau e -amiloide no tecido cerebral. Evidências recentes demonstram que a mucosa olfatória, estrutura periférica e facilmente acessível também está acometida na DA, podendo representar um bom método de diagnóstico preciso e precoce desta moléstia. Os objetivos desse estudo consistem em correlacionar a prevalência das proteínas tau e -amiloide no epitélio olfatório (EO) com os estágios clínicos e neuropatológicos da doença e determinar a sensibilidade e especificidade dos achados no EO para o diagnóstico da DA em seus diferentes estágios de evolução. Para tal fim, é proposto estudo post-mortem, com avaliação de 92 tecidos cerebrais de indivíduos com idade igual ou superior a 50 anos, provenientes do Banco de Encéfalos Humanos do Grupo de Estudos em Envelhecimento Cerebral da Universidade de São Paulo, com coleta dos blocos de mucosa olfatória no momento da autópsia. A avaliação cognitiva foi realizada por meio de entrevista com informante de convívio próximo com o falecido, aplicando as escalas CDR e IQCODE. A avaliação neuropatológica do encéfalo e do EO foi realizada por meio de técnicas de . Os casos foram classificados mediante critério neuropatológico do CERAD e do estadiamento de Braak e Braak para DA. A presença de proteína tau e -amiloide no EO foi correlacionada com os parâmetros clínicos e neuropatológicos obtidos. A análise do EO da concha superior permitiu identificar as proteínas tau e -amiloide com sensibilidade alta, quando comparada com o diagnóstico neuropatológico (>80%) e clínico ( > 90%). Desta forma, a análise para as proteínas tau e - amiloide do epitélio olfatório pode representar um possível biomarcador para diagnóstico da DA / Alzheimer\'s disease (AD) is characterized by a progressive functional and cognitive decline and is considered the most prevalent type of dementia. AD is diagnosed exclusively on the basis of clinical criteria. However, clinical symptoms of AD are preceded by a long asymptomatic period, with silent deposition of tau and amyloid proteins in brain tissue. Recent studies demonstrate the same findings in the olfactory epithelium, a ready accessible structure which could contribute to the precise and early diagnosis of AD. The objectives of the current study were to correlate the prevalence of tau and amyloid proteins distributed in several areas of the olfactory epithelium with clinical and neuropathological criteria used for the diagnosis of AD and to determine the sensitivity and specificity of the olfactory epithelium involvement for the diagnosis of AD. Ninety-two individuals, belonging to the Brazilian Brain Bank of the Aging Brain Study Group from University of São Paulo, whose blocks of olfactory mucosa were collected during autopsy, were tested. Cognitive data were gathered through an interview with a knowledgeable informant, using the CDR (Clinical Dementia Rating Scale) and the IQCODE (Informant Questionnaire on Cognitive Decline in the Elderly) scales. Neuropathological examination was carried out on the basis of accepted criteria, using immunohistochemistry. Neuropathological classification of AD was performed in accordance with the CERAD criteria and Braak & Braak staging. The presence of tau and amyloid protein deposits in the olfactory epithelium was compared with clinical and neuropathological parameters. Immunostaining of olfactory epithelium from the superior turbinate was able to identify tau protein and amyloid-? with high sensitivity when compared with neuropathological scales ( > 80%) and clinical classification of CDR ( > 90%). Thus, immunohistochemistry for tau and amyloid proteins of the olfactory epithelium may represent a potential biomarker for early diagnosis of AD

A Doença de Alzheimer (DA) é a doença mais prevalente entre as demências, retratada por déficits progressivos da memória, funções cognitivas e funcionalidade. Apesar das evidências dos benefícios do exercício físico nas funções cognitivas e no declínio funcional, há poucos estudos com idosos com DA, que incluem efeitos de programas multimodais de exercícios físicos comparados com idosos sem DA. Os objetivos foram comparar os efeitos do programa multimodal de exercícios físicos na capacidade funcional, memória e atenção em idosos sem e com DA. Foram randomizados vinte idosos sem DA para grupo controle (NDA-C) ou grupo treinamento físico (NDA-T) e 18 idosos com DA no grupo controle (DA-C) ou treinamento físico (DA-T). Todos realizaram avaliação do nível sócio econômico, nível de atividade física (Questionário Internacional de Atividade física), e avaliação neuropsicológica (Miniexame do Estado Mental, Teste Breve de Desempenho Cognitivo, Escore Clínico de Demência e Escala de Depressão Geriátrica). A avaliação funcional incluiu testes de resistência muscular de membros inferiores (MMII) e superiores (MMSS) (Teste de Sentar e levantar e Teste de Flexão do cotovelo), capacidade aeróbia (Teste de Marcha estacionária), flexibilidade de MMII e MMSS (Teste de Sentar e alcançar e Teste de Alcançar atrás) e agilidade/equilíbrio dinâmico (Teste de Levantar e ir). A avaliação da amplitude de movimento de ombro e tornozelo foi realizada através do Flexímetro. Os grupos DA-T e NDA-T participaram do programa durante 6 meses, 2 vezes/semana com duração de 75 minutos cada sessão. A análise estatística para verificar diferenças entre os quatro grupos no período inicial foi realizada por Análise de variância (ANOVA) de 1 fator. E para verificar diferenças entre os grupos antes e depois de 6 meses foi realizada ANOVA de 2 fatores. No caso de significância foi realizado uma análise de pos-hoc com Tukey. Admitiu-se, em todas as análises, o nível de significância de 5% (P 0,05). O programa aumentou significativamente (P < 0,05) o nível de atividade física no lazer, a força muscular de MMSS, capacidade aeróbia, flexibilidade de MMII e amplitude de extensão de tornozelo e ombro nos grupos NDA-T e DA- T. Os grupos NDA-T e DA-T melhoraram a capacidade de agilidade e equilibro dinâmico em relação ao grupo DA-C. O programa proporcionou melhora significativa (P < 0,05) na força muscular de MMII do grupo NDA-T e, na flexibilidade de MMSS e amplitude de flexão de tornozelo e ombro no grupo DA-T. Após a intervenção houve melhora significativa (P < 0,05) da memória dos grupos NDA-T e DA-T, e da atenção no grupo NDA-T. Conclui-se que o programa foi efetivo para aumentar o nível de atividade física no lazer, capacidade aeróbia, força muscular de MMSS, flexibilidade de MMII e amplitude de extensão de tornozelo e ombro, bem como a memória dos idosos, independente da presença da DA. O declínio da agilidade/equilibro dinâmico e da atenção do DA-T foi atenuado em relação ao DA-C. Estes benefícios contribuem para um melhor desempenho nas atividades da vida diária melhorando a qualidade de vida dos idosos com e sem DA / The Alzheimer Disease (AD) is the most prevalent disease between all the dementia, and it is portrayed by progressive deficits of memory and cognition. Besides all the evidences of the benefits of the physical exercises to the cognitive function, there are a few studies that include the effects of the multimodal programs on the physical function and cognitive functions, comparing older adults with and without AD. The goals were compare the multimodal program effects in functional capacity, memory and attention on older adults with and without AD. Twenty older adults without AD were randomized on Control Group (NAD-C) or Physical Training Group (NAD-T) and eighteen elderly with AD were randomized on control group (AD-C) or physical training group (AD-T). All patients realized socioeconomic evaluation, physical activities level (International Physical Activities Questionary), and neuropsychological evaluation (Mental State Miniexam, Syndrom Kurztest, Clinical Dementia Rating and Geriatric Depression Screening Scale). On the period of 6 months, the NAD-T and AD-T groups, participated on the multimodal program, the exercise routine was 2 times a week and the duration of 75 minutes. A measuring functional fitness of older adults were applied, the tests evaluated the Inferior and Superior liths muscular Resistance/Strenght (30-second Chair Stand and Arm Curl), Aerobic Capacity (2-minute Step), the lower and upper body flexibility (Chair Sit-and-Reach, and Back Scratch tests) and agility/dynamic balance (8-foot Up and Go). The shoulder and ankle amplitude evaluation tests were realized using a Fleximeter. The statistical analysis to verify if there was any difference between the four groups (NAD-C, NAD-T, AD-C and AD-T) on the initial period were realized using the Variance Analysis (ANOVA) 1way. The statistical analysis to verify the difference between the groups before and after the six months period was realized using the ANOVA 2way. In the case of significance, were used the Tukey Pos-Hoc analysis. In all analysis the level of significance was 5% (P 0.05). The multimodal exercise program was effective to increase the leisure time physical activity level of older adults with or without AD. The program, also contributed to increase the physical conditioning, getting a significant improvement (P<0.05) on the upper body muscular strength, aerobic capacity, upper and lower body flexibility, and, on the Shoulder and Ankle extension amplitude, in the NAD-T and AD-T groups. The NAD-T and AD-T groups improved agility/dynamic balance in relation to the AD-C group. Concerning the cognition, after exercise program, the groups NAD-T and AD-T showed an improvement on the memory (P<0.05). However, the attention only improved in the NAD-T group (P<0.05). Independent of multimodal physical exercise program was improve the leisure time physical activity level, aerobic capacity, upper body muscular strength, lower body flexibility shoulder and ankle extension, and memory in the older adults. The program attenuated the decline in agility/dynamic balance, and attention in DA-T group. These benefits contribute to a better performance in daily living activities which contributes to improve the quality of life of the older adults with and without AD

INTRODUÇÃO: A doença de Alzheimer (DA) é a causa mais frequente de demencia em nosso pais. Sua caracterisica progressiva tem sido muito estudada assim como o estágio pre-clinico intermediário da doença. Alguns estudos epidemiológicos corroboram que idosos com Comprometimento Cognitivo Leve (CCL) apresentam maior risco de desenvolver demência e DA. Os déficits de memória episódica são apontados como o melhor marcador para auxilio no diagnostico diferencial, no entanto, déficits executivos também caracterizam as fases iniciais da DA e se correlacionam clinicamente com sintomas neuropsiquiátricos e perda de desempenho funcional. A Bateria de Avaliação Comportamental da Síndrome Disexecutiva (BADS) é uma bateria de testes utilizada para avaliar problemas que surgem nas atividades de vida diária devido a síndrome disexecutiva. Poucos estudos relataram o desempenho nas funções executivas entre pacientes com CCL, DAPS e DA. OBJETIVOS: Comparar o desempenho na BADS entre indivíduos controles, CCL amnéstico (CCLa) e pacientes com DA de intensidade leve com início pré-senil e senil e também verificar a acurácia da BADS para discriminar entre os grupos. MÉTODOS: A BADS foi administrada em 60 controles saudáveis com média de idade 67,35 (7,40) e escolaridade 9,52 (4,68); 20 pacientes com CCLa média de idade 71,80 (7,79) e escolaridade 9,45 (4,89); 40 pacientes com DA provável sendo 20 pacientes com DAPS com média de idade 59,85 (4,52) , escolaridade 9,40 (4,87) e 20 pacientes com DA senil com média de idade de 79,45 (4,58) e escolaridade 6,45 (3,97). RESULTADOS: Encontramos diferenças significativas no desmpenho na BADS entre os grupos nos subtestes: cartões de troca de regras, programa de ação, mapa do jardim zoológico, seis elementos modificados e nos três escores totais da bateria. Encontramos alterações precoces nas funções executivas em pacientes com DA (independentemente da idade de início) e pacientes com CCLa. O subteste mapa do jardim zoológico, o escore total de perfil e o escore total padronizado da BADS foram capazes de discriminar entre o grupo controle e o grupo de pacientes com CCLa. CONCLUSÃO: A BADS se mostrou útil para discriminar entre os grupos. Nossos resultados confirmaram a presença de alterações precoces das funções executivas em pacientes CCLa e DA leve / INTRODUCTION: Alzheimer Disease (AD) is the most frequent cause of dementia in our country. Its progressive feature has been thoroughly studied as well as the intermediate pre-clinical stage of the disease. Some epidemiological studies corroborate that elderly patients with Mild Cognitive Impairment (MCI) present greater risks of developing dementia and AD. Deficits in episodic memory are pointed out here as the best tool to make the differential diagnosis however, executive deficits are also characteristic of the initial phases of AD and are clinically correlated to neuropsychiatric symptoms and loss of functional performance. The Behavioral Assessment of Dysexecutive Syndrome (BADS) is a battery of tests used to evaluate problems that occur in daily life activities due to the dysexecutive syndrome. A few studies reported the performance of executive syndromes among patients with MCI, PSAD and AD. OBJECTIVES: To compare BADS performance to control group, patients with amnestic MCI (aMCI) and mild onset AD with presenile and senile onset and also check the accuracy of BADS to differentiate among the groups. METHODS: BADS was administered to 60 healthy controls with mean age of 67.35 (7.40) and Educational levels of 9.52 (4.68); 20 patients with aMCI, mean age was 71.80 (7.79) and educational levels of 9.45 (4.89); 40 patients with probable AD out of which 20 patients had PSAD with mean age of 59.85 (4.52), educational levels of 9.40 (4.87) and 20 patients with senile AD with mean age of 79.45 (4.58) and educational levels of 6.45 (3.97). RESULTS: We found significant differences as to BADS performance among the groups in the subtests: rule shift cards, action program, zoo map test, modified six elements and in the three total scores of the battery. We have found early changes in executive functions in patients with AD (regardless of the age at the onset) and patients with aMCI. The subtest, zoo map test, total score and standard score were able to differentiate from the control group and aMCI patients. CONCLUSION: BADS has proved useful to discriminate between groups. Our results confirmed the presence of early changes of executive functions in patients with aMCI and mild AD

by Yao Hong-Bing. / "January 2002." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (p. 113-135). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

阻塞性睡眠呼吸暂停（OSA）是一种常见的睡眠障碍，睡眠过程中反复发作的气道阻塞，导致间歇性低氧血症。OSA 中的間歇性缺氧（IH）一直被视為一個主要致病因素。會影響神經認知功能，包括記憶障礙，遲鈍的反應和其它。以前的研究提示氧化应激产物（ROS）和细胞凋亡是間歇性缺氧引起的认知功能障碍的主要機制之一。然而，确切的机制仍然知之甚少，并没有得到解决。我们基于間隙性缺氧 （IH）的动物模型的实验结果首次发现，即在IH 模型中海馬長時程增強（LTP）的降低，以及腦源性神經營養因子（BDNF）的表达减少。同時我們發現，大脑内注射BDNF 可以有效地恢复LTP 的幅度。因此，我们的研究提供了一种新的可能机制，即在缺乏脑源性神经营养因子可能是阻塞性睡眠呼吸暂停導致的伴有脑功能障碍一个关键因素。 / Ampakine 是一種AMPA 受體調節劑，更重要的是可以增加腦內BDNF 的表達。在这项研究中，我們在不同缺氧時間處理的動物模型中通过腹部注射ampakine 來觀察其效應。我們使用了四组成年雄性小鼠，其中組接受7 天IH处理，另外两组接受14 天缺氧处理。所有四组均分别接受腹腔ampakine 和对照生理盐水注射。 IH 模式仍然是氧含量在90 秒内从21 降到10%，再回复到21%。缺氧时间是每天8 小時周期。从整个IH /正常氧环境的第一天开始，八臂放射迷宮被用来研究参考记忆和工作记忆的表现。然后，我们对脑源性神经营养因子，活性氧和细胞凋亡的分子标记和海马的树突棘形态的表达进行了检查， 海馬突触可塑性的表現，包括E-LTP，L-LTP 也都被檢測。 / Western blot 分析显示，ampakine 注射有效恢复了IH 導致的海马BDNF 水平下降。同时， 我們也發現在ampakine 注射組中ROS 的表达减少，细胞凋亡的减轻，其中包括内质网应激诱导的细胞凋亡。树突棘被認為是海马突触可塑性的结构基础之一。高尔基体染色也表明， ampakine 注射IH 成功回復了7 天IH 導致的較大的，成熟树突棘的減少。 / 此外，八臂放射迷宮的结果表明，无论是参考记忆和工作记忆在7 天IH和14 天IH 均有受損表現。但是，ampkine 的使用同樣挽救了IH 引起的這些记忆障碍。 / 最後，通過研究AMPA 受體調節劑（ampakines）對IH-誘導的神經認知功能障礙及長時程增強障礙影響，我們發現進一步的闡明BDNF 在OSA 所起的重要作用。這些結果也將探索新的藥物治療的OSA 了新的思路。 / 阿爾茨海默病（AD），也叫老年癡呆癥，在65 歲的人的失憶症中，是最常見的原因，也是最常見的神經退行性疾病。 AD 的原因並不清楚，其起病也並不明顯。它的特點是逐漸喪失記憶，語言障礙及其他認知功能障礙，這些症狀可能會變得明顯。在AD 中，兩種蛋白質聚集體的參與和特點的AD 病理澱粉樣斑塊，由澱粉樣蛋白-β 肽，並導致細胞外病變和tau 蛋白纏結，這是由過度磷酸化的絲微管相關蛋白tau，並導致細胞內的病變。 / 鐵是最豐富的微量金屬，在大腦中參與範圍廣泛的細胞過程的運作。然而，鐵臭名昭著的另一方面是其強大的氧化催化性能。事實上，失調的鐵已被發現與細胞老化和各種各樣的神經退行性疾病有牽連。鐵在突觸功能的重要性是對突觸的影響，例如其可以順行軸突運輸突觸功能區域，這也是阿爾茨海默病中的澱粉樣蛋白斑的沉積的起始部位。然而，到現在，鐵的積累是如何影響突觸功能以及更普及的大腦功能很少被研究。 / 為了調查是否高鐵食有任何正常或阿爾茨海默氏病的影響，我們在實驗中引入了APPswe/ps1 轉基因小鼠，這是一個經典的老年癡呆症的疾病的動物模型。研究中，我們使用四組動物模型，即野生型（WT）和APPswe/ps1 小鼠（TG），每組給予至少10 個月正常（ctrl）的食和高鐵（HI）食。 / 海馬LTP 記錄表明，野生小鼠與正常食（WT-HI）的海馬長時程增強下降。 Tg-ctrl 組也相比wt-ctrl 組顯示LTP 水準下降，包括E-LTP 和L-LTP。引人注目的是，高鐵食下的APPswe/ps1 下顯示了被提高和恢復的海馬長時程突觸可塑性。 / 八臂放射迷宮的結果還表明，與高鐵食的野生型以及正常食的APPswe/ps1，無論是在參考記憶體或工作記憶，比野生型與正常食組有較差的記憶水準。同樣，我們驚訝地發現，和APPswe/ps1 正常食的小鼠相比，給予高鐵食的APPswe/ps1 組的迷宮成績要好得多,几乎回复到和野生型对照组一样的水平。 / 這些結果表明，鐵在阿爾茨海默病的功能是非常複雜的，可能會對其神經可塑性顯示雙相調節作用特性。詳細機制有待進一步探討。 / Obstructive sleep apnea (OSA) is a common sleep disorder, characterized by repeated episodes of airway obstruction during sleep resulting in intermittent hypoxemia. Previous studies proposed that reactive oxygen species (ROS) and apoptosis caused by intermittent hypoxia (IH) contributed to cognitive deficits. However, the exact mechanism is still poorly understood and not settled. Our recent studies, for the first time, showed that there is decreased expression of brain-derived neurotrophic factor (BDNF) in the hippocampus and impairment in long-term potentiation (LTP). Intra-brain injection of BDNF can effectively restore the magnitude of LTP. Thus, our study provides a novel mechanism and insight in the etiology of OSA-induced brain dysfunction in that lacking BDNF could be a critical factor. / In this study, ampakine application was used as “BDNF raiser“ during 7-day IH and 14-day IH treatment by intraperitoneal (i.p.) injection. Four groups of adult male mice were used, two of them exposed to 7-day IH and two of them exposed to 14-day IH, each received either vehicle or ampakine i.p. injection. The paradigm of IH consisted of cycles of oxygen levels between 10% and 21% every 90s during the daytime for 8 hrs. Radial arm maze was used to investigate the performance of reference memory and working memory during the whole IH/ normoxia treatment from the first day. After that, expression of BDNF, ROS and molecular markers of apoptosis and morphology of hippocampal dendritic spines were examined, together with the investigation of both hippocamal synaptic plasticity, including early phase LTP (E-LTP) and late phase L-LTP (L-LTP). / Ampakine treatment restored the decreased level of hippocampal BDNF in the IH-treated group, as revealed by Western blot. Meanwhile, decreased ROS expression and alleviated cell death, including ER stress induced-apoptosis are all found in those ampakine injected groups. Golgi staining also showed that ampakine injection IH treatment rescued the decrease of mature dendritc spines, which is the structural basis of hippocampal synaptic plasticity, under 7-day IH treatment. Hippocampal long-term synaptic plasticity, which underlies the proposed mechanism of memory, was also found reversed in those ampakine injected groups, compared with groups under IH treatment. / Furthermore, results of radial arm maze showed that both the reference memory and working memory are impaired by 7-day IH treatment or 14-day IH treatment. However, the application of ampakine rescued IH-induced memory deficits. / Finally, by studying the effects of the ampakines on IH-induced neurocognitive dysfunction and LTP impairment, the role played by BDNF in OSA was further elucidated. These results were shed new lights on the exploration of novel pharmacological treatments in the OSA. / Alzheimer’s disease is the most common cause of dementia among aged people. The causes of AD are not clear and onset of the disease is also not obvious. Iron is the most abundant trace metal in the brain and dysregulation of iron has been implicated in cell aging and a wide variety of neurodegenerative diseases including Alzheimer disease. However, up to now, very little is known about how iron accumulation is involved in Alzheimer disease. / To investigate whether high iron diet has any effects on normal or Alzheimer’s disease, we introduced APPswe/ps1 transgenic mice, an Alzheimer’s disease animal model, and used four groups in our study, namely wild type (wt) and APPswe/ps1 mice (tg), each with normal (ctrl) diets and high iron (HI) diet for at least 10 months. / Hippocampal LTP recording showed that wild type with high iron diet (wt-HI) decreased than that of wt-ctrl group. Tg-ctrl group also displayed decreased LTP level, including E-LTP and L-LTP, than that of wt-ctrl group. Strikingly, that of APPswe/ps1 under HI diets rescued the impaired hippocampal long-term synaptic plasticity than that of APPswe/ps1 mice under normal diets. / Results from radial arm maze also showed that both APPswe/ps1 with normal diet and wild type with HI diet had worse performance, either in reference memory or working memory, than those of wild type with normal diets. Again, it is surprised to find that performances of tg-HI group were much better than APPswe/ps1 mice under normal diet. / These results showed that the function of iron are very complicated, may have different effects on neural function of normal and AD objects. The detailed mechanisms needs to be further explored. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Xie, Hui. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 200-225). / Abstracts also in Chinese. / Declaration --- p.II / ABSTRACT OF THESIS ENTITLED --- p.III / 中文摘要 --- p.VII / Acknowledgements --- p.XI / List of abbreviations --- p.XIII / List of publications --- p.XVI / Chapter CHAPTER 1 --- INTRODUCTION --- p.4 / Chapter 1.1 --- Overview of the study --- p.4 / Chapter 1.2 --- Obstructive sleep apnea --- p.7 / Chapter 1.2.1 --- Epidemiology --- p.8 / Chapter 1.2.2 --- Pathogenesis --- p.10 / Chapter 1.2.3 --- Pathophysiologic Consequences --- p.11 / Chapter 1.2.4 --- Diagnosis --- p.14 / Chapter 1.2.5 --- Treatment --- p.15 / Chapter 1.3 --- Memory and long-term potentiation --- p.17 / Chapter 1.3.1 --- Memory --- p.17 / Chapter 1.3.2 --- Hippocampal Synaptic plasticity --- p.19 / Chapter 1.3.3 --- Dendritic Spines --- p.23 / Chapter 1.4 --- Brain-derived neurotrophic factor --- p.35 / Chapter 1.4.1 --- Introduction of BDNF --- p.35 / Chapter 1.4.2 --- BDNF and synaptic plasticity --- p.36 / Chapter 1.5 --- Intermittent hypoxia impaired memory and neuroplasticity --- p.38 / Chapter 1.5.1 --- Clinical and basic studies on IH-induced neurological dysfunction --- p.38 / Chapter 1.5.2 --- Current mechanisms of IH-induced neurological dysfunction --- p.39 / Chapter 1.5.3 --- ROS generation and intermittent hypoxia --- p.41 / Chapter 1.5.4 --- Critical role of decreased BDNF expression in chronic intermittent hypoxia --- p..46 / Chapter 1.6 --- Ampakine --- p.48 / Chapter 1.6.1 --- Effects of ampakine on receptor activities --- p.49 / Chapter 1.6.2 --- Effects of ampakine on synaptic transmission --- p.50 / Chapter 1.6.3 --- Effects of ampakine on long-term potentiation --- p.52 / Chapter 1.6.4 --- Ampakine, BDNF and neurological disease --- p.53 / Chapter CHAPTER 2 --- METHODS --- p.61 / Chapter 2.1 --- Experimental procedure --- p.61 / Chapter 2.1 --- Animal model of Obstructive Sleep Apnea --- p.62 / Chapter 2.1.1 --- Chronic Intermittent Hypoxia --- p.62 / Chapter 2.1.2 --- Oxygen saturation measurement under normoxia and intermittent hypoxia --- p.64 / Chapter 2.1.3 --- Body weight during hypoxia treatment --- p.64 / Chapter 2.2 --- Western Blot Analysis --- p.65 / Chapter 2.3 --- ROS measurement --- p.67 / Chapter 2.4 --- Golgi staining --- p.67 / Chapter 2.4.1 --- Analysis of spine density --- p.68 / Chapter 2.4.2 --- Measurement of dendritic spines --- p.68 / Chapter 2.5 --- Electrophysiological Experiments --- p.69 / Chapter 2.5.1 --- Brain Slice Preparation --- p.69 / Chapter 2.5.2 --- Multi-electrode Recording Setup (MED64) --- p.70 / Chapter 2.5.3 --- Slice Superfusion --- p.72 / Chapter 2.5.4 --- Field Potential Recordings --- p.73 / Chapter 2.5.5 --- LTP Induction Protocol --- p.74 / Chapter 2.6 --- Radial arm maze --- p.76 / Chapter CHAPTER 3 --- RESULTS --- p.91 / Chapter 3.1 --- Molecular detection under IH treatment and ampakine injection --- p.91 / Chapter 3.1.1 --- BDNF expression under IH treatment and ampakine injection --- p.91 / Chapter 3.1.2 --- ROS measurement under IH treatment and ampakine injection --- p.92 / Chapter 3.1.3 --- Involvement of ER stress during IH treatment --- p.93 / Chapter 3.2 --- Changes of dendritic spines under IH treatment and ampakine injection --- p.100 / Chapter 3.2.1 --- Changes of total dendritic spine density under IH treatment and ampakine injection --- p.100 / Chapter 3.2.2 --- Changes of different dendritic spine density under IH treatment and ampakine injection --- p.101 / Chapter 3.2.3 --- Changes of dendritic spine morphology under IH treatment and ampakine injection --- p.103 / Chapter 3.3 --- IH-induced impairment in hippocampal synaptic plasticity --- p.110 / Chapter 3.3.1 --- E-LTP measurement of 7-day intermittent hypoxia treatment in long-term synaptic plasticity --- p.110 / Chapter 3.3.2 --- L-LTP measurement of 7-day intermittent hypoxia treatment in long-term synaptic plasticity --- p.111 / Chapter 3.3.3 --- E-LTP measurement of 14-day intermittent hypoxia treatment in long-term synaptic plasticity --- p.112 / Chapter 3.3.4 --- L-LTP measurement of 14-day intermittent hypoxia treatment in long-term synaptic plasticity --- p.113 / Chapter 3.4 --- Behavioral studies under IH treatment and ampakine injection --- p.119 / Chapter 3.4.1 --- Reference memory test under IH treatment and ampakine injection --- p.119 / Chapter 3.4.2 --- Working memory measurement under IH treatment and ampakine injection --- p..122 / Chapter CHAPTER 4 --- DISCUSSION --- p.140 / Chapter 4.1 --- Molecular changes under IH treatment and ampakine application --- p.140 / Chapter 4.1.1 --- Intermittent hypoxia down regulate BDNF expression in hippocampus while ampakine injection rescued IH-induced decreased BDNF level --- p.140 / Chapter 4.1.2 --- Ampakine injection against ROS and apoptosis --- p.143 / Chapter 4.1.3 --- Involvement of ER stress-induced apoptosis during IH treatment --- p.145 / Chapter 4.2 --- Changes of spine morphology and density under IH treatment and ampakine injection --- p.146 / Chapter 4.3 --- Ampakine rescued hippocampal synaptic plasticity --- p.152 / Chapter 4.4 --- IH impaired reference memory and working memory --- p.156 / Chapter 4.5 --- Summary --- p.160 / Chapter Chapter 5 --- Effects of High-iron diet in Alzheimer’s Disease --- p..164 / Chapter 5.1 --- Overview of the study --- p.164 / Chapter 5.2 --- Introduction --- p.166 / Chapter 5.2.1 --- Alzheimer's disease --- p.166 / Chapter 5.2.2 --- Function of iron in brain --- p.167 / Chapter 5.2.3 --- Involvement of iron in oxidative damage --- p.168 / Chapter 5.2.4 --- Role of iron in neurodegeneration diseases --- p.168 / Chapter 5.2.5 --- Role of iron in Alzheimer's disease --- p.169 / Chapter 5.2.6 --- Deleterious effects of iron in memory function --- p.171 / Chapter 5.3 --- Methods --- p.172 / Chapter 5.3.1 --- Experimental design --- p.172 / Chapter 5.3.2 --- T-maze --- p.172 / Chapter 5.4 --- Results --- p.174 / Chapter 5.4.1 --- Validation of animal model of Alzheimer's disease --- p.174 / Chapter 5.4.2 --- Examination of normal and high iron diet on body weight --- p.174 / Chapter 5.4.3 --- Effects of Aβ accumulation and high-iron diet on hippocampal synaptic plasticity --- p.175 / Chapter 5.4.4 --- Effects of Aβ accumulation and high-iron diet on spatial memory measured by T-maze --- p.177 / Chapter 5.4.5 --- Effects of Aβ accumulation and high-iron diet on reference memory and working memory measured by radial arm maze --- p.178 / Chapter 5.5 --- Discussion --- p.180 / Chapter Chapter 6 --- General discussion --- p.195 / Reference --- p.200

INTRODUÇÃO: Os estudos epidemiológicos apresentam limitações para a investigação dos fatores relacionados à senescência e à senilidade cerebral. A correlação clinicopatológica é o padrão-ouro para o diagnóstico definitivo de doença de Alzheimer (DA) e permite identificar os casos de DA em fase pré-clínica. Ainda há controvérsia acerca da existência de um limiar neuropatológico separando o envelhecimento normal da DA ou se há constituição de uma reserva cognitiva que protegeria idosos contra os achados cerebrais desta deonça. Este estudo visa investigar os mecanismos do processo de envelhecimento cerebral, através da busca de fatores associados com o processo natural de envelhecimento, DA pré-clínica e demência causada por DA. MÉTODOS: Estudo post-mortem, avaliando 141 indivíduos com idade igual ou superior a 80 anos, participantes do Banco de Cérebros do Projeto Envelhecimento Cerebral. Avaliação cognitiva foi realizada através de entrevista com informante de convívio próximo com o falecido, aplicando as escalas CDR e IQCODE. Avaliação neuropatológica foi realizada através de técnicas de imunohistoquímica, valendo-se do critério neuropatológico do CERAD e do NIA-RI e do estadiamento de Braak e Braak. Os participantes foram classificados como envelhecimento natural se: CDR=0 e CERAD=0 ou A e estágio de BraakIII, como DA pré-clínica se CDR=0 e CERAD B ou C e estágio de Braak IV e como portadores de demência por DA quando apresentaram CDR2 e CERAD B ou C e estágio de Braak IV. Dados demográficos, perfil funcional e comportamental, tabagismo, etilismo, hipertensão arterial, diabetes mellitus, doenças cardio e cerebrovascular e depressão foram comparados entre os grupos. A presença de alterações microvasculares foi registrada. RESULTADOS: Porcentagem considerável dos indivíduos portadores de CDR=0 preencheu um ou mais critérios neuropatológicos para DA. (29,8%, 31,6% e 19,3%, de acordo com o estadiamento de Braak e Braak e critérios do CERAD e NIA-RI, respectivamente). Gênero feminino foi mais prevalente no grupo demência por DA (OR:6,35 IC95%:1,58-25,51). Tabagismo foi mais prevalente entre os indivíduos do grupo envelhecimento normal quando comparado ao grupo DA pré-clínica (OR:4,44 IC95%:1,04-19,01) e ao subgrupo de mulheres portadoras de demência por DA (OR:9,00 IC95%:1,56-51,87). Maior nível educacional foi encontrado no grupo DA pré-clínica, comparado ao envelhecimento normal, de acordo com o estadiamento de Braak e Braak (OR:1,22 por ano estudado IC95%:1,01-,147). CONCLUSÕES: Um limiar neuropatológico associado à DA não pode ser determinado com base nos critérios neuropatológicos atuais. Em uma população muito-idosa, indivíduos com cognição intacta podem frequentemente abrigar achados cerebrais disseminados típicos de DA. Estes indivíduos provavelmente possuem maior reserva cognitiva, influenciada pelo nível de escolaridade. O tabagismo associa-se com menor concentração de achados cerebrais típicos de DA / BACKGROUND: Epidemiologic studies are limited to investigate the factors related to brain senescence and senility. The clinicopathological assessment is the gold standard for an accurate diagnosis of Alzheimer disease (AD) and permits the identification of the pre-clinical AD cases. It is a matter of debate whether there is a threshold for AD-type pathology to become clinically manifested or a cognitive reserve protecting individuals against cerebral burden. This study attempts to investigate the mechanisms related to brain aging process by searching for the factors associated with normal aging, pre-clinical AD and AD dementia. METHODS: A post-mortem study evaluating 141 cases, aged 80 years or older, randomly selected from the Brain Bank of the Brazilian Aging Brain Study. Cognitive evaluation was gathered through the CDR and the IQCODE, applied with a knowledgeable informant of the deceased. Neuropathologic examinations were performed using immunohistochemistry and were classified according to the CERAD and NIA-RI criteria and Braak and Braak staging. Cases were classified as normal aging if: CDR = 0, IQCODE <3.20, CERAD = 0 or A and Braak and Braak stage III. The pre-clinical AD group included subjects with CDR=0, IQCODE <3.20, CERAD B or C and Braak stage IV. Cases were considered as AD dementia when presented CDR 2, IQCODE > 3.80, CERAD B or C and Braak and Braak stage IV. Demographical data, functional and behavioral profile, history of cigarette smoking, alcohol abuse, hypertension, diabetes, stroke, cardiovascular disease and depression were compared between the groups. Microvascular findings were registered. RESULTS: A considerable percentage of CDR=0 subjects fulfilled one or more neuropathologic criteria for AD. (29.8%, 31.6% and 19.3%, according to Braak and Braak staging, CERAD and NIA-RI criteria, respectively). Female gender (OR:6.25 95% CI: 1.58-25.51) was associated to AD when compared to normal aging group. Cigarette smoking was more prevalent among the individuals of the normal aging group when compared to both the pre-clinical AD group (OR: 4.44 95%CI:1.04-19.01) and the female gender AD dementia subgroup. (OR: 9.00 95%CI:1.56-51.87). A higher educational level was found significant on the preclinical AD group when compared to normal aging group, according to Braak and Braak staging (OR: 1.22 per year of education 95%CI:1.011,47). CONCLUSION: A minimum neuropathologic threshold for AD cannot be determined based on current diagnostic criteria. On a very-old population, cognitively normal subjects can frequently harbor disseminate pathology of AD. These individuals probably have a higher cognitive reserve in which educational level may play an important role. Cigarette smoking is associated with lower burdens of AD-like pathologic findings in the brain

INTRODUÇÃO: A Mini-Addenbrooke\'s Cognitive Examination (M-ACE) consiste em um teste de avaliação cognitiva breve composta de cinco itens que visam avaliar quatro domínios cognitivos principais (orientação, memória, linguagem e função viso-espacial) com pontuação máxima de 30 pontos e um tempo de administração de cinco minutos. OBJETIVO: Avaliar o desempenho de idosos cognitivamente saudáveis, com CCL e DA leve na versão brasileira da M-ACE. MÉTODOS: o teste foi aplicado um grupo de 23 pacientes com DA provável leve, 36 CCL e 25 idosos cognitivamente saudáveis. Todos os participantes incluídos tinham idade >= 60 anos. Foram excluídos pacientes com demência de intensidade moderada ou grave, demência de outra etiologia, comorbidades graves com potencial de comprometer a cognição e uso de medicação psicotrópica. A acurácia do teste foi avaliada por meio da análise das curvas ROC. Para analisar a relação entre os escores da M-ACE e os demais testes cognitivos aplicados foram utilizados os coeficientes de correlação de Spearman. Para analisar a consistência interna da M-ACE e suas três versões foi utilizado o coeficiente alfa de Cronbach. RESULTADOS: Houve um predomínio do gênero feminino, a média de idade foi de 73 anos, com faixa etária predominante de 60-69 anos. A média de escolaridade obtida foi de 11 anos. A M-ACE apresentou alta consistência interna (alfa de Cronbach > 0,8; IC 95% 0,776 a 0,869) e mostrou ser extremamente capaz de diferenciar o grupo DA dos demais participantes, com uma acurácia superior ao MEEM. O ponto de corte de 20 foi o de maior sensibilidade e especificidade (95,6% e 90,16% respectivamente), com área sob a curva considerada alta (ASC = 0,805; IC 95% 0,705 -0,904). A M-ACE apresentou melhor precisão em diferenciar os três grupos quando comparado com o MEEM (71,43 versus 60,71). Observou-se ainda uma precisão mais robusta em diferenciar DA de CCL com a M-ACE (63,89 versus 30,56 no MEEM). O escore total da M-ACE não sofreu considerável influência da idade e escolaridade. A M-ACE apresentou forte correlação com MEEM (cor = 0,78), bem como todos os itens (exceto percepção) da BBRC e QAF (cor = -0,76). CONCLUSÃO: A M-ACE pode ser considerada um teste rápido de rastreio com elevada acurácia no diagnóstico de DA. O ponto de corte sugerido neste estudo é de 20 para DA e 27 para CCL / INTRODUCTION: The Mini-Addenbrooke\'s Cognitive Examination (M-ACE) consists of a brief cognitive assessment test composed of five items that aim to evaluate four main cognitive domains (orientation, memory, language and visuospatial function) with a maximum score of 30 points and a time of administration of five minutes. OBJECTIVE: Evaluate the performance of cognitively healthy elderly, MCI and mild AD in the Brazilian version of M-ACE. METHODS: The test was applied to a group of 23 patients with mild probable AD, 36 MCI and 25 cognitively healthy elderly. All included participants were aged >= 60 years. Patients with moderate or severe dementia, dementia of another etiology, severe comorbidities with potential to compromise cognition and use of psychotropic medication were excluded. The accuracy of the test was evaluated by analyzing the ROC curves. Spearman\'s correlation coefficients were used to analyze the relationship between the M-ACE scores and the other cognitive tests applied. In order to analyze the internal consistency of the M-ACE, the Cronbach\'s alpha coefficient was used. RESULTS: There was a predominance of females, mean age was 73 years, with a predominant age range of 60-69 years. The average level of schooling was 11 years. MACE presented high internal consistency (Cronbach\'s alpha > 0.8, 95% CI 0.776 to 0.869) and showed to be extremely capable of differentiating the AD group from the other participants, with a higher accuracy than the MMSE. The cutoff point of 20 was the one with the highest sensitivity and specificity (95.6% and 90.16%, respectively), with an AUC considered to be high (AUC = 0.805, 95% CI 0.705-0.904). The M-ACE presented better accuracy in differentiating the three groups when compared to the MMSE (71.43 versus 60.71). It was also observed a more robust precision in differentiating DA of MCI with M-ACE (63.89 versus 30.56 in MMSE). The total M-ACE score was not very influenced by age and schooling. M-ACE showed a strong correlation with MMSE (spearman = 0.78), as well as all items (except perception) of BBRC and QAF (spearman = -0.76). CONCLUSIONS: M-ACE can be considered a brief screening tool with high accuracy in the diagnosis of AD. The cutoff point suggested in this study is 20 for AD and 27 for MCI

A doença de Alzheimer (DA) é uma doença neurodegenerativa e a principal causa de demência em idosos. Os mecanismos fisiopatológicos mais envolvidos na DA são: o acúmulo do peptídeo beta amiloide (A?) em agregados extracelulares, e a formação dos emaranhados neurofibrilares (ENF). A Proteína Precursora do Amiloide (APP) é clivada pelas secretases alfa (ADAM10), beta (BACE1) e y (Presenilina 1 [PSEN1]). As plaquetas contêm 95% da APP circulante e possuem toda a maquinaria necessária para estudar perifericamente a APP e suas secretases. A pesquisa de biomarcadores na DA tem como objetivo identificar, em vida, os indicadores do processo patogênico em fluídos corporais e/ou por métodos de imagem cerebral. O objetivo do presente estudo foi investigar proteínas envolvidas no metabolismo da APP em plaquetas de pacientes com DA e o potencial de modificação destas vias pela ação do tratamento com cloridrato de donepezila. Para tanto foram analisadas amostras de 23 pacientes com DA leve ou moderada, avaliados antes e depois de 6 meses de tratamento e 38 indivíduos idosos cognitivamente saudáveis (controles). As variáveis de desfecho estudadas foram: (1) expressão protéica de ADAM10, BACE1 e PSEN1; (2) expressão protéica dos metabólitos secretados da APP de 110 e 130kDa, possibilitando o cálculo da razão de APP (rAPP); e (3) atividade enzimática das APP-secretases ADAM10 e BACE1. Foram utilizados os métodos de western blotting e o fluorimétrico. Encontramos, nos pacientes com DA pré-tratamento, uma diminuição da rAPP em relação aos controles; porém, não identificamos diferenças após seis meses de tratamento. Os níveis de ADAM10 mostraram-se menores em pacientes com DA na avaliação basal quando comparados aos controles, mas também sem modificação com o tratamento, o tratamento mostrou-se associado a uma redução da expressão de BACE1 em pacientes com DA, embora não tenhamos encontrado diferenças entre pacientes e controles na avaliação basal. A expressão de PSEN1 mostrou-se menor nos pacientes com DA pré-tratamento quando comparada aos controles, sem contudo haver alteração em resposta ao tratamento. Quanto à atividade enzimática de ADAM10 e BACE1, não observamos diferenças nos valores pré e pós-tratamento. Nossos achados reforçam a utilidade da utilização de plaquetas como matriz biológica para o estudo do metabolismo da APP em tecidos periféricos e para a investigação de efeitos modificadores da patogenia da DA a partir do tratamento com drogas antidemência / Alzheimer\'s disease (AD) is a neurodegenerative disease and the major cause of dementia in the elderly. The main mechanisms in AD are: extracellular aggregates of beta amyloid peptide (Abeta) and neurofibrillary tangles formation (NFT). Amyloid Precursor Protein (APP) is cleaved by the secretases alfa (ADAM10), beta (BACE1) and ? (Presenilin 1 [PSEN1]). Platelets containing 95% of the circulating APP and possess all the machinery necessary to study peripherically APP and its secretases. The search for biomarkers in AD aims to identify, in life, the pathogenic process indicators in body fluids and/or brain image methods. The aim of this study was to investigate proteins involved in APP metabolism in platelets of AD patients, and the potential modification of these pathways by treatment with Donepezil hydrochloride. Therefore, 23 patients with mild to moderate AD evaluated before and after 6 months treatment and 38 healthy elderly subjects (controls) were analyzed. Outcome variables were: (1) ADAM10, BACE1 and PSEN1 expression; (2) APP secreted metabolites expression (110 and 130kDa), allowing the APP ratio (rAPP) estimate; (3) APP-secretase ADAM10 and BACE1 enzymatic activity. Western blotting and fluorimetric methods were used. We found in AD patients pre-treatment, a decrease of rAPP compared to controls; however, we did not identify differences of this parameter after six months of treatment. The ADAM10 levels were lower in AD patients at baseline when compared to controls, however no differences were observed after treatment. Treatment was associated with a reduction of BACE1 expression in AD patients, although we have not found differences between patients and controls at baseline. PSEN1 expression was lower in pre-treatment AD patients compared to controls. No differences were observed after treatment. Concerning to BACE1 and ADAM10 enzymatic activity, we did not observe differences in pre and post-treatment. Our findings strengthen the use of platelets as a biological matrix for the APP metabolism as well as the modifying effects on AD pathogenicity of antidementia drugs