A doença de Alzheimer é uma doença neurodegenerativa que causa perdas de memória, danos cognitivos e no comportamento, sendo considerada uma das causas principais de demência entre a população. Esta doença é caracterizada por uma intensa perda neuronal colinérgica, de forma que tanto os inibidores da enzima acetilcolinesterase (AChE) quanto compostos antioxidantes possam ser empregados como neuroprotetores. Nesse sentido, plantas da família Lycopodiaceae vêm sendo estudadas como fonte de novos alcalóides anticolinesterásicos desde a descoberta da huperzina A, isolada a partir da planta chinesa Huperzia serrata. Este trabalho foi realizado com o objetivo de caracterizar e isolar os alcalóides majoritários de Huperzia acerosa, H. heterocarpon, H. quadrifariata, H. reflexa, Lycopodiella cernua, Lycopodium clavatum e L. thyoides, de ocorrência no estado do Rio Grande do Sul, bem como avaliar as atividades anticolinesterásicas e antioxidantes in vitro e in vivo para os extratos. Extratos de alcalóides totais de espécies de L. clavatum e L. thyoides ocorrentes no Brasil e Argentina foram comparados quanto ao seu conteúdo químico, aliado à atividade anticolinesterásica. A atividade inibitória para AChE e butirilcolinesterase (BuChE) dos alcalóides isolados também foi ensaiada, juntamente com a determinação das propriedades citotóxicas exercidas pelos extratos sobre uma linhagem de gliomas C6. Todos os extratos de alcalóides foram analisados através de CG-EM, sendo os perfis de fragmentação dos compostos comparados através de dados da literatura. L. clavatum e L. thyoides possuem perfil químico similar, com licopodina e acetildiidrolicopodina como alcalóides principais, enquanto que L. cernua possui apenas dois alcalóides, cernuína e licocernuína. Os extratos de alcalóides de H. acerosa, H. quadrifariata e H. reflexa também foram analisados, sendo detectados tanto compostos do grupo licopodano quanto do grupo flabelidano, juntamente com outros alcalóides cujas estruturas ainda são desconhecidas. Os alcalóides encontrados em H. heterocarpon não puderam ser elucidados a partir de dados de fragmentação, uma vez que eles não coincidiram com nenhum perfil da literatura. Nesse estudo verificamos que dentre os extratos analisados, H. quadrifariata e H. reflexa promoveram a maior inibição para a enzima AChE obtida de eritrócitos humanos, com IC50 de 2,0 e 0,11 μg/mL, respectivamente, enquanto que H. heterocarpon foi o único extrato com maior seletividade para a BuChE (IC50 = 8,3 μg/mL). Além disso, dentre os alcalóides isolados licopodina, acetildiidrolicopodina, cernuína, licocernuína e clavolonina, apenas acetildiidrolicopodina e cernuína possuem inibição importante, sendo que nenhum deles possui efeito butirilcolinesterásico significativo. Também foi estimada a atividade anticolinesterásica para os extratos de alcalóides totais de L. clavatum e L. thyoides empregando-se homogenatos de córtex, hipocampo e estriato de ratos como fonte enzimática, sendo determinadas suas curvas de inibição com distintos tempos de incubação em uma faixa de concentrações. Também foi verificada para os dois extratos uma inibição do tipo competitiva/não-competitiva, bem como seu perfil antioxidante in vitro pelos métodos de descoloração do radical DPPH, degradação da 2-deoxirribose, TRAP e óxido nítrico. Após um tratamento agudo em camundongos de 14 meses com os extratos, foram verificados os efeitos antioxidantes através do método de TBA-RS, e para as enzimas catalase e superóxido dismutase. Do mesmo modo, verificamos que os mesmos extratos promoveram uma diminuição na atividade da acetilcolinesterase, quando administrados por via intraperitoneal. Nessa metodologia, os extratos mais potentes foram H. quadrifariata e H. reflexa, corroborando o efeito in vitro encontrado para os mesmos. Os extratos purificados de alcalóides de L. clavatum e L. thyoides com habitat no Brasil e Argentina foram comparados quanto ao seu perfil químico e biológico. Nesse estudo, foi verificado que os alcalóides licopodina e acetildiidrolicopodina são os compostos majoritários para todas as espécies, tendo L. clavatum maior atividade anticolinesterásica em relação a L. thyoides, tanto a espécie brasileira quanto a espécie argentina. / Alzheimer’s disease is a neurodegenerative disease which causes memory loss, cognitive and behavioral damages, considered to be the leading cause of dementia among the elderly. This disease is characterized for an intense cholinergic loss, and the use of acetylcholinesterase (AChE) inhibitors together with antioxidant compounds as neurprotectors is a strategy for the treatment. In this sense, Lycopodiaceae plants are well studied as a source of new anticholinesterasic alkaloids since the discovery of huperzine A, isolated from Chinese Huperzia serrata. This work was conducted with the objective of characterize and isolate the main alkaloids from Huperzia acerosa, H. heterocarpon, H. quadrifariata, H. reflexa, Lycopodiella cernua, Lycopodium clavatum and L. thyoides, with occurrence in Rio Grande do Sul state, and also evaluate the anticholinesterasic and antioxidant activities in vitro and in vivo for the extracts. Alkaloidal extracts from L. clavatum and L. thyoides species with habitat in Brazil and Argentina were compared to their chemical content, together with their anticholinesterasic activity. The inhibitory effect for AChE and butyrylcholinesterase (BuChE) for the isolated alkaloids was also evaluated, together with the determination of the cytotoxic properties exherced by the extracts in a gliome C6 cell line. Every alkaloidal extract was analyzed by means of GC-MS, and the fragmentation patterns for the compounds were compared with those from literature. L. clavatum and L. thyoides have similar chemical profile, with lycopodine and acetyldihydrolycopodine as main alkaloids, while L. cernua has only two alkaloids, cernuine and lycocernuine. The alkaloidal extracts of H. acerosa, H. quadrifariata e H. reflexa were also analyzed, and compounds from lycopodane and flabellidane groups were detected, along with other alkaloids whose structures are still unknown. The alkaloids found in H. heterocarpon could not be elucidated with fragmentation dates so far, since they did not coincide with those found in literature. We also verified that among the extracts, H. quadrifariata and H. reflexa promoted a higher inhibition for AChE obtained from human erythrocytes, with a IC50 value of 2,0 e 0,11 μg/mL, respectively, while H. heterocarpon extract was the only more selective for BuChE (IC50 = 8,3 μg/mL). Moreover, among the isolated alkaloid lycopodine, acetyldihydrolycopodine, cernuine, lycocernuine and clavolonine, only acetyldihydrolycopodine and cernuine possess an important inhibition, and none significantly inhibited butyrylcholinesterase. It was also assessed the anticholinesterase effect for the alkaloidal extracts of L. clavatum and L. thyoides employing cortex, hippocampus and striatum rat brain homogenates as enzymatic sources, being determined the incubation time-inhibition curves over a concentrations range. It was also verified for both extracts an inhibitory effect of the competitive/non competitive mixed type, as well as their in vitro antioxidant profile using the methods of DPPH radical decoloration, 2-deoxyrribose degradation, TRAP and nitric oxide. After an acute treatment in 14 months-aged mice, we verified the antioxidant effects though TBA-RS and also the enzymes catalase and superoxide dismutase. In the same way, we found out that the same extracts reduced the acetylcholinesterase activity when administered by intraperitoneal injection. Using this methodology, the most potent extracts were H. quadrifariata and H. reflexa, corroborating the in vitro effect found for them. The purified alkaloidal extracts of L. clavatum and L. thyoides with habitat in Brazil and Argentine were compared to their chemical and biological profile. In this study, we found out that lycopodine and acetyldihydrolycopodine are the main alkaloids found for all species, and L. clavatum possesses a better inhibition against AChE when compared to L. thyoides for both Brazilian and Argentinean collected species.

Introdução: Indíviduos com danos cerebrais podem apresentar dissociação na produção de verbos e substantivos. Há uma maior diversidade de transtornos neurológicos que apresentam prejuízo na produção de verbos do que de substantivos, e esses transtornos normalmente apresentam danos em circuitos cerebrais frontais. No entanto, pouco se sabe sobre a natureza do prejuízo na produção de verbos em cada transtorno neurológico. Objetivo: A presente tese de doutorado teve como objetivo investigar a produção de verbos em diferentes doenças neurodegenerativas e no envelhecimento normal através das tarefas de fluência e nomeação de verbos. Métodos: para atingir o objetivo geral, foram realizados três estudos que originaram três artigos científicos. O primeiro artigo realizou uma adaptação da tarefa de fluência de verbos para o português brasileiro, obteve a performance de 62 brasileiros idosos saudáveis para esta tarefa e a influência de fatores demográficos, clínicos e da aplicação de outras tarefas de fluência verbal previamente à fluência de verbos. O segundo artigo investigou a natureza dos déficits da produção de verbos na doença de Alzheimer (DA). Para isso 35 pacientes com DA em fase leve e moderada foram avaliados para as tarefas de fluência e nomeação de verbos, assim como 35 idosos saudáveis (controles). Também analisou-se a influência da frequência das palavras nas tarefas estudadas. O terceiro artigo, investigou a natureza dos déficits na produção de verbos na Afasia Progressiva Primária (APP) não-fluente. Foram avaliados 12 pacientes com APP não-fluente e 9 sujeitos controle. Todos partcipantes foram avaliados através de tarefas de nomeação e fluência de verbos e de substantivos. Um efeito de manipulabilidade foi estudado na tarefa de nomeação. Correlatos neurais foram investigados utilizado a técnica de Voxel Based Morphometry (VBM) a partir de imagens de ressonância magnética (RM) estrutural dos pacientes. Resultados: No primeiro artigo obteve-se a performance dos idosos saudáveis na fluência de verbos (11,73±5,80), a correlação com a escolaridade (r=0,616), MEEM escore total (r=0,399), MEEM Atenção e Cálculo (r=0,393), e MEEM Linguagem (r=0,322). Não houve influência da aplicação prévia de tarefas de fluência verbal na fuência de verbos. No segundo artigo, os pacientes com DA mostraram prejuízo tanto na tarefa de nomeação de verbos (p<0,000; F=36,983) quanto na fluência de verbos (p<0,000; F=21,460), porém a primeira foi mais comprometida que a segunda. A performance dos pacientes com DA na nomeação de verbos foi influenciada pela severidade da doença e pela frequência das palavras. No terceiro artigo, os pacientes com APP não-fluente foram comprometidos em todas tarefas de nomeação e de fluência verbal, porém foram significativamente piores em verbos do que em substantivos. Não houve efeito de manipulabilidade. As áreas atróficas Broadmann 44 (p<0,001) e giro pré-central (p<0,001) se correlacionaram com o prejuízo na nomeação de verbos, enquanto as áreas atróficas 44 e 45 de Broadman (p<0,001, ambas) se correlacionaram com o prejuízo na fluência de verbos. Conclusões: Nossos achados indicam que o prejuízo na produção de verbos parece ter uma natureza predominantemente semântica na DA e prodominantemente gramatical na APP não fluente. As evidências levantam questões importantes também para a neurobiologia da linguagem. / Background: Individuals with brain damage may show dissociation in the verb and noun production. There is a larger diversity of neurological disorders that show impairment in verbs rather in nouns, and these disorders use to present damage in the frontal brain circuits. However, little is known about the nature of the verb production impairment in each one of these neurological disorders. Objective: The current doctoral thesis had the aim of investigating the verb production in different neurodegenerative diseases and in the normal elderly, using verb fluency and verb naming tasks. Methods: to reach the main aim, we carried out three studies that resulted in three articles. In the first article we adapted the verb fluency task for Brazilian Portuguese, we obtained the performance of 62 healthy elderly people for this task, and we verified the influence of demographic and clinical factors as well as of the previous application of other verbal fluency tasks. The second article investigated the nature of the verb production deficits in the Alzheimer’s disease (AD). Thirty-five mild and moderate AD patients and 35 healthy controls were evaluated for verb fluency and verb naming tasks. It also analyzed the influence of word frequency in the used tasks. The third article investigated the nature of verb production deficits in the nonfluent variant of Primary Progressive Aphasia (nfPPA). Twelve patients with nfPPA and 9 healthy controls were evaluated for verb and noun fluency and naming tasks. A manipulability effect was studied in the naming task. Neural correlates were investigated by Voxel Based Morphometry (VBM) of structural Magnetic Ressonance Imaging (MRI) of the patients. Results: The first article obtained the healthy elderly people performance for verb fluency (11.73±5.80), a correlation with education (r=0.616), MMSE total score (r=0.399), MMSE Attention and Calculation (r=0.393), and with MMSE Language (r=0.322). There was no influence of previous application of verbal fluency tasks on the verb fluency. In the second article, the AD patients showed deficits in the verb naming (p<0.000; F=36.983) and in the verb fluency (p<0.000; F=21.460), however the first task was more impaired than the second one. The AD patients performance in the verb naming was influenced by the disease severity and by word frequency. In the third article, the nfPPA patients were impaired in all naming and fluency tasks, however they were significantly worse in verbs than in nouns. There was no effect of manipulability. Atrophy on BA 44 (p<0.001) and on precentral gyrus (p<0.001) correlated with impairment in verb naming. Atrophy on BA 44 and 45 (p<0.001 for both) correlated with impairment in verb fluency. Conclusions: Our findings indicate the verb production deficits seem to have a more predominant semantic nature in AD and more predominant grammatical nature in nfPPA. This evidence brings up important questions for the neurobiology of language.

Introdução: Indíviduos com danos cerebrais podem apresentar dissociação na produção de verbos e substantivos. Há uma maior diversidade de transtornos neurológicos que apresentam prejuízo na produção de verbos do que de substantivos, e esses transtornos normalmente apresentam danos em circuitos cerebrais frontais. No entanto, pouco se sabe sobre a natureza do prejuízo na produção de verbos em cada transtorno neurológico. Objetivo: A presente tese de doutorado teve como objetivo investigar a produção de verbos em diferentes doenças neurodegenerativas e no envelhecimento normal através das tarefas de fluência e nomeação de verbos. Métodos: para atingir o objetivo geral, foram realizados três estudos que originaram três artigos científicos. O primeiro artigo realizou uma adaptação da tarefa de fluência de verbos para o português brasileiro, obteve a performance de 62 brasileiros idosos saudáveis para esta tarefa e a influência de fatores demográficos, clínicos e da aplicação de outras tarefas de fluência verbal previamente à fluência de verbos. O segundo artigo investigou a natureza dos déficits da produção de verbos na doença de Alzheimer (DA). Para isso 35 pacientes com DA em fase leve e moderada foram avaliados para as tarefas de fluência e nomeação de verbos, assim como 35 idosos saudáveis (controles). Também analisou-se a influência da frequência das palavras nas tarefas estudadas. O terceiro artigo, investigou a natureza dos déficits na produção de verbos na Afasia Progressiva Primária (APP) não-fluente. Foram avaliados 12 pacientes com APP não-fluente e 9 sujeitos controle. Todos partcipantes foram avaliados através de tarefas de nomeação e fluência de verbos e de substantivos. Um efeito de manipulabilidade foi estudado na tarefa de nomeação. Correlatos neurais foram investigados utilizado a técnica de Voxel Based Morphometry (VBM) a partir de imagens de ressonância magnética (RM) estrutural dos pacientes. Resultados: No primeiro artigo obteve-se a performance dos idosos saudáveis na fluência de verbos (11,73±5,80), a correlação com a escolaridade (r=0,616), MEEM escore total (r=0,399), MEEM Atenção e Cálculo (r=0,393), e MEEM Linguagem (r=0,322). Não houve influência da aplicação prévia de tarefas de fluência verbal na fuência de verbos. No segundo artigo, os pacientes com DA mostraram prejuízo tanto na tarefa de nomeação de verbos (p<0,000; F=36,983) quanto na fluência de verbos (p<0,000; F=21,460), porém a primeira foi mais comprometida que a segunda. A performance dos pacientes com DA na nomeação de verbos foi influenciada pela severidade da doença e pela frequência das palavras. No terceiro artigo, os pacientes com APP não-fluente foram comprometidos em todas tarefas de nomeação e de fluência verbal, porém foram significativamente piores em verbos do que em substantivos. Não houve efeito de manipulabilidade. As áreas atróficas Broadmann 44 (p<0,001) e giro pré-central (p<0,001) se correlacionaram com o prejuízo na nomeação de verbos, enquanto as áreas atróficas 44 e 45 de Broadman (p<0,001, ambas) se correlacionaram com o prejuízo na fluência de verbos. Conclusões: Nossos achados indicam que o prejuízo na produção de verbos parece ter uma natureza predominantemente semântica na DA e prodominantemente gramatical na APP não fluente. As evidências levantam questões importantes também para a neurobiologia da linguagem. / Background: Individuals with brain damage may show dissociation in the verb and noun production. There is a larger diversity of neurological disorders that show impairment in verbs rather in nouns, and these disorders use to present damage in the frontal brain circuits. However, little is known about the nature of the verb production impairment in each one of these neurological disorders. Objective: The current doctoral thesis had the aim of investigating the verb production in different neurodegenerative diseases and in the normal elderly, using verb fluency and verb naming tasks. Methods: to reach the main aim, we carried out three studies that resulted in three articles. In the first article we adapted the verb fluency task for Brazilian Portuguese, we obtained the performance of 62 healthy elderly people for this task, and we verified the influence of demographic and clinical factors as well as of the previous application of other verbal fluency tasks. The second article investigated the nature of the verb production deficits in the Alzheimer’s disease (AD). Thirty-five mild and moderate AD patients and 35 healthy controls were evaluated for verb fluency and verb naming tasks. It also analyzed the influence of word frequency in the used tasks. The third article investigated the nature of verb production deficits in the nonfluent variant of Primary Progressive Aphasia (nfPPA). Twelve patients with nfPPA and 9 healthy controls were evaluated for verb and noun fluency and naming tasks. A manipulability effect was studied in the naming task. Neural correlates were investigated by Voxel Based Morphometry (VBM) of structural Magnetic Ressonance Imaging (MRI) of the patients. Results: The first article obtained the healthy elderly people performance for verb fluency (11.73±5.80), a correlation with education (r=0.616), MMSE total score (r=0.399), MMSE Attention and Calculation (r=0.393), and with MMSE Language (r=0.322). There was no influence of previous application of verbal fluency tasks on the verb fluency. In the second article, the AD patients showed deficits in the verb naming (p<0.000; F=36.983) and in the verb fluency (p<0.000; F=21.460), however the first task was more impaired than the second one. The AD patients performance in the verb naming was influenced by the disease severity and by word frequency. In the third article, the nfPPA patients were impaired in all naming and fluency tasks, however they were significantly worse in verbs than in nouns. There was no effect of manipulability. Atrophy on BA 44 (p<0.001) and on precentral gyrus (p<0.001) correlated with impairment in verb naming. Atrophy on BA 44 and 45 (p<0.001 for both) correlated with impairment in verb fluency. Conclusions: Our findings indicate the verb production deficits seem to have a more predominant semantic nature in AD and more predominant grammatical nature in nfPPA. This evidence brings up important questions for the neurobiology of language.

Submitted by MARCIA ROVADOSCHI (marciar@unifra.br) on 2018-08-16T14:24:58Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao_FrancineRodriguesIaniski.pdf: 3871772 bytes, checksum: ea06b31c8ed51f3bf9a88cbfb0d4956c (MD5) / Made available in DSpace on 2018-08-16T14:24:58Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao_FrancineRodriguesIaniski.pdf: 3871772 bytes, checksum: ea06b31c8ed51f3bf9a88cbfb0d4956c (MD5) Previous issue date: 2011-12-02 / Alzheimer's disease (AD) is a chronic neurodegenerative pathologic process associated with aging. This disease causes cognition deterioration and memory loss. The formation of senile plaques containing amyloid-β peptide (aβ) is the main characteristic of this disease. Also, AD related with the inflammation and oxidative stress. The lack of drugs used in the prevention and treatment of AD has stimulated the search for new agents that may represent a novel therapeutic alternative. In the present study, we investigated the beneficial effect of meloxicam-loaded nanocapsules in a model of AD induced by intracerebroventricular (i.c.v.) injection of aβ peptide (fragment 25-35) in mice, comparing the effect with free meloxicam. Mice were divided into six groups: (I) control, (II) aβ, (III) Nano, (IV) Free, (V) Nano + aβ and (VI) Free + aβ. Mice were treated with meloxicam-loaded nanocapsules (5 mg/kg, by gavage), free-meloxicam (5 mg/kg, by gavage) or blank nanocapsules. Thirty minutes after treatments, aβ (3 nmol) or filtered water were i.c.v. injected (day 1). Learning and memory were assessed with the Morris water-maze and step-down-type passive-avoidance tasks at the days 4–7 and 7–8 after the aβ injection, respectively. At the end of the experimental protocol, animals were died and brains were removed for determination of reactive species (RS) and non-protein thiols (NPSH) levels, and superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), glutathione S-transferase (GST) activities. The results demonstrated that aβ injection caused learning and memory deficits in mice, which were verified using the Morris water-maze and step-down-type passiveavoidance tasks. Furthermore, this study showed that oxidative stress was increased in mice that received aβ. The most important findings of the present study was that meloxicam-loaded nanocapsules protected the learning and memory impairments induced by aβ. Moreover, meloxicam-loaded nanocapsules also protected against the increase of oxidative stress. However, free-meloxicam did not have protective effect. All these findings support the beneficial role of meloxicam-loaded nanocapsules in a model of AD induced by aβ. We can suggest that nanocapsules favor the passage of meloxicam through the blood-brain barrier and entry of the drug in the central nervous system. / A doença de Alzheimer (DA) é um processo patológico neurodegenerativo crônico associado ao envelhecimento. Essa patologia ocasiona deterioração da cognição e perda da memória. A formação de placas senis contendo o peptídeo β-amiloide (βa) é a principal característica dessa doença, que também está associada à inflamação e ao estresse oxidativo. A falta de fármacos empregados na prevenção e no tratamento da DA tem estimulado a pesquisa por novos agentes que possam representar uma inovadora alternativa terapêutica. No presente estudo, investigamos o efeito benéfico das nanocápsulas contendo meloxicam sobre o déficit de aprendizagem e de memória em um modelo da DA induzido pela injeção intracerebroventricular (i.c.v.) do peptídeo βa (fragmento 25-35) nos camundongos, comparando o efeito com o fármaco na forma livre. Os camundongos foram divididos em seis grupos: (I) Controle, (II) βa, (III) Nano, (IV) Livre, (V) Nano + βa, (VI) Livre + βa. Os camundongos foram pré-tratados com as nanocápsulas contendo meloxicam (5 mg/kg, por gavagem), ou com o fármaco na forma livre (5 mg/kg, por gavagem), ou com as nanocápsulas brancas. Trinta minutos após os tratamentos, foram injetados i.c.v. o peptídeo βa (3 nmol) ou água filtrada (dia 1). A aprendizagem e a memória foram avaliadas através dos testes do labirinto aquático de Morris e da esquiva passiva, nos dias 4-7 e 7-8 após a injeção do peptídeo βa, respectivamente. No final dos testes comportamentais, os animais foram mortos e os cérebros removidos para a determinação dos níveis de espécies reativas (ER) e tióis nãoproteicos (SHNP), e a atividade das enzimas superóxido dismutase (SOD), catalase (CAT), glutationa peroxidase (GPx), glutationa redutase (GR) e glutationa S-transferase (GST). Os resultados demonstraram, através dos testes do labirinto aquático de Morris e da esquiva passiva, que a injeção i.c.v. do peptídeo βa causou um déficit na aprendizagem e na memória dos camundongos. Além disso, esse estudo demonstrou que o estresse oxidativo foi aumentado nos camundongos que receberam a injeção i.c.v. do peptídeo βa. Os achados mais importantes desse estudo foram que as nanocápsulas contendo meloxicam protegeram o déficit de aprendizado e de memória induzidas pela injeção i.c.v. do peptídeo βa, assim como foram capazes de proteger contra o aumento do estresse oxidativo. No entanto, o meloxicam na forma livre não apresentou esse efeito protetor. Todos esses achados reforçam o papel benéfico do meloxicam nanoencapsulado em um modelo da DA induzido pela injeção i.c.v. do peptídeo βa, sugerindo que as nanocápsulas favorecem a passagem do meloxicam através da barreira hematoencefálica (BHE) e a entrada do fármaco no sistema nervoso central (SNC)

Alzheimer’s disease (AD) is a neurodegenerative disorder characterized by two major pathological hallmarks, amyloid plaques and neurofibrillary tangles. The accumulation of amyloid-β protein (Aβ) is an early event associated with synaptic and mitochondrial damage in AD. Therefore, molecular pathways underlying the neurotoxicity and generation of Aβ represent promising therapeutic targets for AD. Recent studies have shown that actin severing protein, Cofilin plays an important role in synaptic remodeling, mitochondrial dysfunction, and AD pathogenesis. However, whether Cofilin is an essential component of AD pathogenesis and how Aβ induced neurotoxicity impinges its signals to Cofilin are unclear. In my dissertation studies, we found Aβ oligomers bind with intermediate activation conformers of β1-integrin to induce the loss of surface β1-integrin and activation of Cofilin via Slingshot homology-1 (SSH1) activation. Specifically, conditional loss of β1-integrin prevented Aβ induced Cofilin activation, and allosteric modulation or activation of β1-integrin significantly reduced Aβ binding to neurons and mitigated Aβ42-induced reactive oxygen species (ROS) generation, mitochondrial dysfunction, synaptic proteins depletion, and apoptosis. Furthermore, we found that SSH1 reduction, which mitigated Cofilin activation, prevented Aβ-induced mitochondrial Cofilin translocation and apoptosis, while AD brain mitochondria contained significantly increased activated/oxidized Cofilin. In mechanistic support in vivo, we demonstrated that APP transgenic mice brains contain decreased SSH/Cofilin and SSH1/14-3-3 complexes which indicates that SSH-Cofilin activation occurred by releasing of SSH from 14-3-3. We also showed that genetic reduction in Cofilin rescues APP/Aβ-induced synaptic protein loss and gliosis, as well as impairments in synaptic plasticity and contextual memory in vivo. Our lab previously found that overexpression of the scaffolding protein RanBP9 increases Aβ production in cell lines and in transgenic mice, while promoting Cofilin activation and mitochondrial dysfunction. However, how endogenous RanBP9 activates cofilin and whether endogenous RanBP9 accelerates Aβ-induced deficits in synaptic plasticity, cofilin-dependent pathology, and cognitive impairments were unknown. In my dissertation studies, we found that endogenous RanBP9 positively regulates SSH1 levels and mediates A-induced translocation of Cofilin to mitochondria. Moreover, we demonstrated that endogenous RanBP9 mediates A-induced formation of Cofilin-actin rods in primary neurons. Endogenous level of RanBP9 was also required for Aβ-induced collapse of growth cones in immature neurons and depletion of synaptic proteins in mature neurons. In vivo, we also found APP transgenic mice exhibit significantly increased endogenous RanBP9 levels and that genetic reduction in RanBP9 rescued APP/Aβ-induced synaptic protein loss, gliosis, synaptic plasticity impairments, and contextual memory deficits. These findings indicated that endogenous RanBP9 not only promotes Aβ production but also meditate Aβ induced neurotoxicity via positively regulating SSH1. Taken together, these novel findings implicate essential involvement of β1-integrin–SSH1/RanBP9–Cofilin pathway in mitochondrial and synaptic dysfunction in AD pathogenesis.

La maladie d’Alzheimer (MA) est la plus répandue des maladies neurodégénératives. Elle se caractérise par une déficience cognitive puis fonctionnelle souvent associée à des Symptômes Psychologiques et Comportementaux des Démences (SPCD). Les études longitudinales de corrélations physiopathologiques des SPCD sont rares et difficiles à évaluer en raison de grandes hétérogénéités dans les populations étudiées. Associée à l’expertise clinique, la neuroimagerie fournit des indices cruciaux pour comprendre les corrélats neuroanatomiques des SPCD les plus invalidants dans la MA. Dans les travaux de recherche, il apparaît déterminant de considérer la MA associée à certaines co-pathologies neurodégénératives et vasculaires. En effet, alors que les patients jeunes sont les plus touchés par des lésions pures, le vieillissement favorise l'apparition de co-lésions liées à la MA et aux Maladies à Corps de Lewy (MCL) et Maladies CérébroVasculaires (MCV).Soutenu par un travail bibliographique sur la MA et ses co-lésions, ce travail de thèse s’appuie sur 3 études complémentaires. La 1ière porte sur une revue de littérature ayant pour objectif d’évaluer les corrélats neuroradiologiques des SPCD dans la MA. Différents moteurs de recherche de données bibliographiques ont permis d’identifier 118 études évaluant cet objectif. Un modèle global des corrélats cérébraux des SPCD a été proposé pour soutenir la forte implication de la région frontale. Aussi, des stratégies méthodologiques ont été suggérées pour aider à diriger de futures recherches. La 2ième étude avait pour objectif d’évaluer si le profil d’atrophie cérébrale pouvait déterminer le risque de développer des SPCD dans la MA. Une analyse volumétrique de données IRM a été effectuée pour évaluer l’atrophie régionale en incluant 53 patients MA sans SPCD significatifs à l’inclusion et 40 contrôles. Vingt-quatre structures dans les régions frontale, temporale, pariétale, occipitale et sous-corticale ainsi que dans le cervelet ont été identifiées comme associées aux SPCD. L'atrophie frontale semble être le prédicteur le plus significatif des SPCD. La 3ième étude s’inscrit en continuité et en perspective de ce travail de thèse. Elle a pour but d’explorer ces questions chez des patients atteints de MA associée à des co-lésions de MCL et MCV / Alzheimer's disease (AD) is the most common neurodegenerative disease. AD is characterized by cognitive and functional impairment often associated with Behavioural and Psychological Symptoms of Dementia (BPSD). Longitudinal studies of pathophysiological correlations of BPSD are rare and difficult to evaluate due to large heterogeneities in the populations studied. Associated with clinical expertise, neuroimaging provides crucial clues to understand the neuroanatomic correlates of the most disabling BPSD in AD. It seems important to consider in the research, AD with some neurodegenerative and vascular co-pathologies. Indeed, while young patients are the most affected by pure lesions, aging favors the appearance of co-lesions related to AD and Lewy body disease and cerebrovascular diseases.Supported by a bibliographic work on AD and its co-lesions, this work is based on 3 complementary studies. The first concerns a literature review aimed at evaluating neuroradiological correlates of BPSD in AD. Bibliographic search has led to 118 studies evaluating this objective. A global pattern of cerebral cortical brain regions has been proposed to support the strong involvement of the frontal region. Also, methodological strategies have been suggested to help direct future research. The aim of the second study was to evaluate whether the profile of cerebral atrophy could determine the risk of developing BPSD in AD. A volumetric analysis of MRI data was performed to evaluate regional atrophy by including 53 patients with no significant BPSD at baseline and 40 controls. Twenty-four structures in the frontal, temporal, parietal, occipital and subcortical regions as well as in the cerebellum were identified as associated with BPSD. Frontal atrophy appears to be the most significant predictor of BPSD. The third study is in continuity of this work of thesis. It is intended to explore these issues in patients with AD associated with co-lesions

This study explores cognitive impairment and its correlation to early- life adverse experiences in non-patient population between the ages of 50 to 65. This developmental approach and observational study design explores cognition in pre-clinical Alzheimer’s disease (AD). Using a standardized neuropsychological instrument, the Montreal Cognitive Assessment (MoCA) and clinically administered questionnaire, the ACE (Adverse Childhood Experiences), I hypothesized that participants with high ACE scores will inversely have low MoCA scores. My goal was to use a multiple linear regression model with 3 covariates and 1 predictor of interest (ACEs). At 80% power, a sample size of 40 was calculated as needed. This would mean that the results would have 80 % chance of declaring statistical significance. This corresponds to an R-squared value (percentage of variation in MoCA score explained by the predictor) of 17.2%. The desired sample size was not attained successfully due to several barriers in receiving sample data from the collaborating site and the 2017 Hurricane Irma causing a drop in participation rate. Overall 13 participants had successfully participated. The analysis of the results is demonstrated in a line graph indicating a relationship between ACE and MoCA scores. The accuracy of the descriptive statistics could be argued against due to the low sample size. The analysis of the ethnographic interviews brings out some trends in the participant responses. The focus here has been to discuss these responses as to how they advocate for the entanglement theory of aging. In other words, how the exposure to social and environmental factors at various stages of an individual’s lifecourse can interact with one’s physiology, resulting in exposure- specific health conditions at later life stages. Among the period of exposure, my focus through this study is specifically on the early exposures in the lifecourse. This is facilitated by the use of the ACE questionnaire regarding exposures to adverse experiences such as sexual/ physical abuse, familial mental health issues, alcohol/ drug abuse in the family and loss or separation from parents. The entanglement theory further allows for race or culture specific exposures to adversity that raises the question of varying health consequences among cultural or racial groups and the need for a more critical approach in providing access to healthcare and healthcare policy development. Trends in ethnographic results obtained have allowed for the critical discourse in the transgenerational effects of social adversity, effects of resilience- building from adversity and the need for care- giver mental health services. The study brought out critiques on how the ACE module could be made more inclusive of experiences specific to diverse cultures and regions, as well as the need to address the severity of individual experiences. We conclude by discussing how effects of social or environmental experiences can be used toward AD and aging research and what supporting literature and initiatives currently exist. The discussion is also inspired by the existing political discourse around the medicalization of AD and how that influences the reductionist methods in AD research. This new direction of applied and holistic approach derives its perspective from neuroanthropology and applied medical anthropology. The overall aim of this study is to ask questions challenging existing research methods with the ultimate hope to newly influence the allocation of AD research and risk reduction toward interdisciplinary focus and funding, involving early-life lived experiences and life course perspectives.

La maladie d’Alzheimer est souvent précédée de troubles cognitifs légers (MCI) associés à la lésion du cortex entorhinal, une région interconnecté avec l’hippocampe. Cependant, un tiers des patients MCI présentent une rémission cognitive suggérant l’action de mécanismes compensatoires. Ces mécanismes pourraient être déficitaires chez les patients porteurs de l’allèle APOE4 présentant un MCI plus agressif.Par des approches multidisciplinaires chez la Souris, ce travail a démontré que la lésion entorhinale induit des déficits comportementaux et une hyperactivité de l’hippocampe. Or, le bourgeonnement des fibres cholinergique dans l’hippocampe compense ces déficits. Comme le bourgeonnement cholinergique est inhibé en présence de l’APOE4, cela pourrait contribuer au déclin cognitif exacerbé de ces patients. Par conséquent, l’inhibition de l’hyperactivité hippocampique chez les 50% de patients APOE4 représente une alternative prometteuse pour le traitement symptomatique du MCI. / Mild Cognitive Impairments (MCI) often precedes Alzheimer’s disease (AD) and is characterized by the loss of entorhinal neurons leading to a hippocampal disconnection. However, MCI patients also revert to normal cognition, suggesting compensatory mechanisms that alter the disease progression. This compensation may be impaired in patients bearing the APOE4 allele that are more prone to MCI, present less cognitive reversion and faster transition to AD.This work in mice, demonstrated that the sprouting of cholinergic fibers compensates entorhinal lesions through the reduction of the related hippocampal hyperactivity. As in APOE4 mice the cholinergic sprouting was altered in association with cognitive impairments, such impaired synaptic compensation may contribute to the faster cognitive decline of these patients. Therefore, supporting or mimicking the cholinergic control on hippocampal hyperactivity may represent a promising alternative therapeutic strategy for APOE4-carriers.

Les mitochondries jouent un rôle primordial dans la survie et la mort cellulaire car elles gouvernent à la fois le métabolisme énergétique et les voies apoptotiques. Un dysfonctionnement mitochondrial dans les neurones peut donc conduire à la neurodégénérescence ou à une neuropathologie. Notre objectif a été d'étudier la régulation de la fonction mitochondriale, en particulier la bioénergétique, pour contribuer à l'amélioration des connaissances actuelles sur les mitochondries. Nos résultats montrent que: i) les neurostéroïdes améliorent la bioénergétique mitochondriale en stimulant la respiration cellulaire en condition normale; ii) les neurostéroïdes réduisent les déficits bioénergétiques observés dans la maladie d'Alzheimer; iii) l'horloge circadienne développe une régulation réciproque avec la bioénergétique et la dynamique mitochondriales. Les résultats de cette thèse ouvrent des perspectives intéressantes pour l'élaboration de stratégies régulatrices de l'homéostasie métabolique chez le sujet sain et chez le patient atteint d'une pathologie due à un dysfonctionnement mitochondrial et/ou une altération des rythmes biologiques. / Mitochondria play a paramount role in cell survival and death because they are orchestrating both energy metabolism and apoptotic pathways, while impaired mitochondrial function leads inevitably to disease, especially neurodegeneration. The purpose of the present thesis was therefore to deepen our understanding of the regulation of mitochondrial function, with a focus on mitochondrial bioenergetics and dynamics. Our key findings were that: i) neurosteroids represent promising molecules which are able to increase mitochondrial bioenergetics via enhancement of mitochondrial respiration in healthy condition; ii) neurosteroids are able to alleviate Alzheimer’s disease-related bioenergetic deficits; iii) the circadian clock is able to regulate mitochondrial bioenergetics and dynamics, and vice versa. Collectively, our results contribute to a better understanding of how mitochondria function, and could have multiple implications with regard to the regulation of metabolic homeostasis in health and disease states associated with mitochondrial impairments and/or circadian disruption.

Dans cette thèse nous avons étudié le stade débutant de la maladie d'Alzheimer par deux approches distinctes. D'un point de vue fondamental, nous avons étudié le rôle des oligomères d'Aß dans un modèle d'injection intracérébrale de ces espèces solubles chez la souris sauvage. Nous avons notamment montré que ces injections engendraient chez l'animal des désordres mnésiques aigus et réversibles qui s'apparentent à la maladie d'Alzheimer. Nous avons aussi mis en évidence une diminution d'expression d'une protéine post-synaptique (PSD95), une augmentation de la phosphorylation de la protéine Tau et une hyperactivation neuronale induites par ces injections, Ces modifications histo-fonctionnelles généralisées concordent avec le profil de dissémination diffus des solutions peptidiques injectées comme en atteste la mise en évidence de peptide Aß dans des régions distantes du site d'injection en immunohistochimie mais aussi en spectrométrie de masse. D'un point de vue clinique nous avons étudié la valeur du Rappel Libre/Rappel Indicé 16 items (RLRI16), un test de mémoire épisodique, au sein d'une cohorte de patients consultant pour une plainte mnésique ayant participé à un essai thérapeutique multicentrique national. Dans cette cohorte, le RLRI16 s'est avéré être le meilleur prédicteur de la survenue d'une démence d'Alzheimer probable dans les 5 ans qui ont suivi son administration. Le grand nombre de participants, la durée de l'étude et le mode de recrutement (par les généralistes) nous ont permis de proposer des valeurs seuils qui pourront aider le clinicien dans sa pratique quotidienne et permettront de définir des critères d'inclusion dans de nouveaux essais thérapeutiques. / We studied the early phase of Alzheimer’s disease with two approaches, experimental and clinical. Firstly, experimentally, we injected Aβ oligomers in the brain of wild type mice. We showed that these soluble species elicited memory impairment reminiscent of those found in AD although in our case they were both acute and reversible. We also evidenced a decrease in the expression of a postsynaptic protein (PSD95), an increase in the phosphorylation of Tau and a neuronal hyperactivity one week after these injections. These histo-functional changes were observed throughout the brain. The diffusion of the Aß injectate shown by immunohistochemistry and by mass spectrometry imaging was widespread. Clinically, we confirmed the usefulness of a memory test, the Free and Cued Selective Reminding Test (FCSRT) to predict the risk of dementia of the Alzheimer’s type (DAt) up to 5 years prior to its onset. This was made possible by the study of a cohort of patients who consulted for memory complaints and were then included in a multicentric national clinical trial conducted in France. In this cohort, the FCSRT proved to be the best predictor of the further conversion to a DAt. The large number of participants, length of the follow-up and recruitment type (mainly by the general practitioners) allowed us to derive thresholds to be used by clinicians in their daily practice or as inclusion criteria in new clinical trials.