Made available in DSpace on 2016-03-22T17:27:35Z (GMT). No. of bitstreams: 1 FERNANDAPEDROTTI_MESTRADO.pdf: 708081 bytes, checksum: 5ee01fbf7025bcd8bfa8448519f5340e (MD5) Previous issue date: 2014-11-13 / Background: Generalized Anxiety Disorder (GAD) is a common psychiatric disorder characterized by long term worry, tension, nervousness, fidgeting and symptoms of autonomic system hyperactivity. The neurobiology of this disorder is still unclear, although it has been consistently demonstrated that the environment and the genetic profile could increase its risk. We examined whether a polymorphism in the BDNF gene, which plays a role in neuroplasticity and memory, could increase the vulnerability to this disorder. Methods: In our study, 816 subjects from a population-based study were genotyped by qPCR for the BDNF functional variant rs6265 (Val66Met) and the BDNF serum levels were measured by ELISA. Results: Our results revealed a significant association between the Met allele and risk for GAD (p=0.014), but no differences were observed in the serum levels of BDNF according to diagnosis (p=0.531) or genotype distribution (p=0.197). The interaction between Val66Met genotype and GAD in explaining serum BDNF levels approached significance (F=3.93; p=0.048). The logistic regression analysis confirmed the independent association of Met allele as a risk factor to develop GAD after adjusting for confounders (β=1.92; 95% IC: 1.168-3.16; p=0.010. Conclusion: These results suggest that BDNF could be involved in the neurobiology of GAD and might represent a useful marker associated with the disease. Key words: Anxiety disorders, generalized anxiety disorder, brain-derived neurotrophic factor, BDNF serum levels, Val66Met polymorphism / O transtorno de ansiedade generalizada (TAG) é uma doença crônica, caracterizada pelo excesso de ansiedade e preocupação somada à presença de outros sintomas, como tensão muscular, e irritabilidade (Hanrahan et al, 2013; Zargar et al, 2013). De acordo com o Manual Diagnóstico e Estatístico de Transtornos Mentais (DSM-IV), esse transtorno normalmente inicia na adolescência e afeta cerca de 5,7% da população em geral com altas taxas de incidência em mulheres (Kessler et al, 2005; Tempesta et al, 2013). Além disso, o TAG tem considerável impacto na qualidade de vida, sendo responsável por prejuízos na vida social, profissional e familiar dos seus portadores (Zargar et al, 2013; Tempesta et al, 2013). O TAG, geralmente é acompanhado de comorbidades psiquiátricas como a depressão maior, outros transtornos de ansiedade, e abuso de álcool, sendo caracterizado por altas taxas de falha na terapêutica, o que dificulta a resposta ao tratamento, bem como a resposta a psicoterapia (Zargar et al, 2013; Grant et al, 2005). O TAG é uma doença complexa na qual ocorre a interação de múltiplos fatores ambientais, biológicos e genéticos, cuja neurobilogia exata permanece ainda desconhecida (Zargar et al, 2013; Chen et al, 2006). O fator neurotrófico derivado do cérebro (BDNF), membro da família das neurotrofinas, age sobre certos neurônios do SNC e periférico, desempenhando um papel importante na sobrevivência, diferenciação e crescimento neuronal durante o desenvolvimento e na idade adulta (Gratacos et al, 2007; Egan et al, 2004). No cérebro está presente em regiões específicas como hipocampo, neocortex e hipotálamo, regiões-chave na regulação do humor e comportamento, bem como na aprendizagem e memória, indicando um envolvimento direto na patofisiologia das doenças psiquiátricas (Yoshii and Constantine-Paton, 2010; Lu et al, 2008). Estudos clínicos e pré-clínicos com transtornos de ansiedade demonstram que alterações no gene e nos níves de BDNF podem estar associados a doença (Hartmann et al., 2001; Rasmusson et al., 2002; Molle et al., 2012). Porém os estudos nesta área são escassos e inconsistentes, mas indicam que indivíduos com TAG apresentam uma maior frequência do alelo Met (Suliman et al, 2013; Ball et al, 2013). Dessa forma, uma melhor compreensão de alguns fatores genéticos envolvidos nos transtornos de ansiedade poderá permitir avanços não só ao nível de tratamento, mas também de prevenção e diagnóstico, podendo algumas alterações neurobiológicas vir a integrar os critérios de diagnóstico e monitoramento da doença, hoje exclusivamente semiológicos, e contribuir, assim, para a explicação da heterogeneidade desta patologia

MTOR est une sérine/thréonine kinase appartenant au complexe mTORC1 (mTOR Complexe 1), un régulateur clé de la traduction. Ce complexe joue un rôle au sein de la LTP (Potentialisation à Long Terme), une forme de plasticité synaptique qui requiert la synthèse de nouvelles protéines pour renforcer la transmission synaptique. La première partie de ma thèse porte sur les mécanismes de régulation de la voie mTORC1 dans les neurones. Dans les cellules non neuronales, cette voie de signalisation est classiquement régulée par deux voies distinctes. D’une part, les acides aminés induisent le recrutement du complexe mTORC1 à la membrane des endo-lysosomes où la protéine Rheb est enrichie et favorisent ainsi l’activation de mTORC1. D’autre part, les facteurs de croissance activent mTORC1 en stimulant la voie PI3K/Akt/TSC/Rheb. Nos résultats indiquent que les neurones sont capables d’ "utiliser" le mécanisme responsable de la translocation de mTORC1 en réponse à la supplémentation en acides aminés pour coupler l’induction de la plasticité synaptique à l’activation de mTORC1. En effet, les récepteurs NMDA et le BDNF, deux acteurs centraux de la LTP, augmentent le recrutement de mTORC1 à la membrane des endo-lysosomes même en absence d’acides aminés, et activent mTORC1. Par des stratégies induisant la translocation de mTORC1 à la membrane des endo-lysosomes, nous avons montré que ce mécanisme est important pour l’activation de mTORC1 mais n’est pas suffisant : il faut également une activation de la protéine Rheb. Le second aspect de mon projet porte sur la régulation de mTORC1 dans le cadre de la maladie d’Alzheimer, une maladie neurodégénérative caractérisée par une perte progressive de la mémoire. Les déficits cognitifs s’accompagnent d’un dysfonctionnement progressif des synapses suivi par la perte neuronale, tous deux causés par une accumulation anormale du peptide amyloïde β (Aβ). Les données de la littérature montrent que les oligomères toxiques du peptide Aβ (AβO) inhibent la plasticité synaptique dans les stades précoces de la maladie. Cependant, les mécanismes restent obscurs. Plusieurs études mettent en évidence une altération de la voie mTORC1. Nos résultats montrent que les AβO inhibent le recrutement de mTORC1 à la membrane des endo-lysosomes. Ce mécanisme est rétabli par une inhibition pharmacologique de l’AMPK. Ainsi, ces données indiquent que les AβO inhibent l’adressage de mTORC1 aux compartiments endo-lysosomaux via l’AMPK. Cela aurait pour conséquence une inhibition de la synthèse protéique décrite dans la littérature et contribuerait ainsi au dysfonctionnement synaptique. / MTOR is a serine/threonine kinase that belongs to mTORC1 (mTOR complex 1), a key regulator of translation. This complex is involved in LTP (Long Term Potentiation), a form of synaptic plasticity requiring new protein synthesis to reinforce synaptic transmission. The first part of my thesis investigates the mechanism of mTORC1’s regulation in neurons. In non-neuronal cells, mTORC1 pathway is commonly activated by two distinct pathways. On the one hand, amino acids induce mTORC1 recruitment to the membrane of endo-lysosomes where Rheb is enriched and can thus promote mTORC1 activation. On the other hand, growth factors activate mTORC1 via the PI3K/Akt/TSC/Rheb pathway. Our results indicate that neurons are capable of “using” amino acid-induced translocation of mTORC1 to connect synaptic plasticity induction to mTORC1 activation. Indeed, NMDA receptors and BDNF, two main actors of synaptic plasticity, increase mTORC1 recruitment to the membrane of endo-lysosomes even in the absence of amino acids, and activate mTORC1. Using strategies targeting mTORC1 to endo-lysosomes, we show that this mechanism promotes activation of mTORC1 but is not sufficient: Rheb activation is also required. The second part of my project is focused on the regulation of mTORC1 in Alzheimer’s disease, a neurodegenerative pathology characterized by a progressive memory loss. Cognitive deficits are widely believed to result from a progressive dysfunction of synapses, followed by a loss of neurons, both caused by an abnormal accumulation of the amyloid β peptide (Aβ). Data from others show that toxic Aβ oligomers (AβOs) inhibit synaptic plasticity at early stages of the disease. However, the mechanisms remain poorly understood. Several studies indicate an alteration of the mTORC1 pathway. Our results show that AβOs inhibit mTORC1 recruitment to the membrane of endo-lysosomes and that this effect can be rescued by a pharmacological inhibition of AMPK. Thus our data indicate that AβOs inhibit mTORC1 translocation to endo-lysosomal compartments via AMPK. This could lead to the impairment of protein synthesis reported in other studies and thus alter synaptic function.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Taking into account the unknow etiology of neuropsychiatry disturbances, including bipolar disorder (BD) and the bad eating habbits, the purpose of this study was to evaluate the influence of chronic consumption of trans fat, remaining in a large amount in processed foods, on lipid composition of striatal membranes, as well as its biochemical-molecular alterations in this tissue. To perform this study, a second generation of male rats born from mothers and grandmothers supplemented with soybean oil (SO-C, an isocaloric control group) or hydrogenated vegetable fat (HVF, rich in TFA) (3 g/kg; p.o.) since gestational period until adulthood was used. They were kept under oral treatment until adulthood, when they were exposed to an AMPH-induced model of mania (4 mg/Kg/ml/day, i.p., during 14 days). The HVF group presented 0.38% of TFA incorporation in the striatum, affecting Na+/K+ ATPase enzyme activity, which was decreased per se and following AMPH-exposure. The HVF group also showed increased protein carbonyl (PC) and brain-derived neurotrophic factor (BDNF) mRNA levels after AMPH administration, while these oxidative and molecular changes were not observed in the other experimental groups. Additionally, a negative correlation between striatal Na+/K+ ATPase activity and PC levels (r2= 0.49) was observed. The prolonged consumption of HVF, rich in TFA, allowed that FA incorporation and increases striatal oxidative status, thus impairing the functionality of Na+/K+ATPase and affecting molecular targets as BDNF mRNA. We hypothesized that the chronic intake of processed foods (rich in TFA) facilitates the development of neuropsychiatric diseases, particularly the bipolar disorder. / Levando em consideração a etiologia desconhecida dos transtornos neuropsiquiátricos, incluindo o transtorno bipolar (TB) e os maus hábitos alimentares, o propósito desse estudo foi avaliar a influência do consumo crônico de gordura trans, que ainda se encontra presente em grandes quantidades em alimentos processados, sobre a natureza das membranas estriatais de ratos, assim como alterações bioquímico-moleculares nesse tecido, em ratos expostos a um modelo animal de mania. Para a realização este estudo, a 2a geração de ratos machos nascidos de mães e avós suplementadas com óleo de soja (OS-C) ou gordura vegetal hidrogenada (GVH) (3 g/kg; via oral) desde o período gestacional até a idade adulta foram utilizados. Eles foram mantidos sob a mesma suplementação de suas mães até a idade adulta, quando foram expostos a um modelo animal de mania induzido por anfetamina (ANF) (4 mg/Kg/ml/dia, i.p.; durante 14 dias). O grupo suplementado com GVH apresentou uma incorporação de 0.38% de ácidos graxos trans (AGT) no estriado comparado com o grupo OS-C, afetando a atividade da enzima Na+/K+ ATPase, que foi diminuída per se e após a administração de ANF. Além disso, o grupo suplementado com GVH apresentou níveis aumentados de proteína carbonil (PC) e do RNAm do fator neurotrófico derivado do encéfalo (BDNF) após administração de ANF, o que não foi observado nos outros grupos experimentais. Adicionalmente, uma correlação negativa entre a atividade estriatal da enzima Na+/K+ ATPase e níveis de PC (r2=0.49) foi observada. O prolongado consumo de GVH, rica em AGT, permitiu a incorporação destes AG e aumentou o status oxidativo estriatal, comprometendo a atividade da Na+/K+ ATPase e afetando alvos moleculares como RNAm do BDNF. Nós hipotetizamos que a ingesta crônica de alimentos processados (ricos em AGT) pode facilitar o desenvolvimento de doenças neuropsiquiátricas, entre elas o transtorno bipolar.

Made available in DSpace on 2016-03-15T19:39:56Z (GMT). No. of bitstreams: 1 Cyntia Moraes Teixeira.pdf: 299481 bytes, checksum: 9bb0d211bcfc9fdcd4b0b8dbed28d6e4 (MD5) Previous issue date: 2012-08-09 / Universidade Presbiteriana Mackenzie / Obesity has been considered epidemic in the whole world and is a risk factor for the development of hypertension, dyslipidemia, hyperglycemia, type 2 diabetes and hepatic steatosis. The increase of obesity in during pregnancy not only increases the risk of developing cardiovascular diseases but may also be related to abnormalities in the developing CNS of embryos, for example, reduction of potential long-term (LTP) in the hippocampus and neurogenesis . It is possible that the reduced levels of BDNF observed in these embryos, are involved with the injury in the processes of learning and memory observed in these animals. Studies also show that BDNF is reduced in fetuses of mothers with maternal subclinical hypothyroidism. These puppies have worsening neurological development, with deficits in long and short term memory. Here we evaluated whether maternal obesity may alter levels of BDNF and enzyme expression of type III deiodinase (D3) in the brains of pups, with consequent alteration of local levels of T3 to 7 °, 10 ° and 16 ° day-old post -natal. Our results showed that obesity reduced the expression of D3 on the 7th day of postnatal life of the offspring of obese mothers, but not in later days. There were no significant alterations in the levels of BDNF in any of the evaluated days. Our data suggest that it is possible that thyroid hormone is involved in neurophysiological abnormalities observed in offspring of obese rats. / A obesidade é uma epidemia de ordem mundial que é fator de risco para o desenvolvimento de hipertensão arterial, dislipidemia, hiperglicemia, diabetes tipo 2 e esteatose hepática. O aumento de obesidade em gestantes além de aumentar o risco do desenvolvimento de doenças cardiovasculares, também pode estar relacionado com anomalias no desenvolvimento do Sistema Nervoso Central dos embriões como, por exemplo, redução dos potenciais de longa duração (LTP) e da neurogênese no hipocampo. É possível que os níveis reduzidos de BDNF observados nestes embriões, estejam envolvidos com o prejuízo nos processos de aprendizado e memória exibidos por esses animais. Estudos também mostram que o BDNF se encontra reduzidos em fetos de mães com hipotiroidismo subclínico materno. Estes filhotes apresentam piora no desenvolvimento neurológico, demonstrando déficits na memória de longo e de curto prazo. O presente avaliou se a obesidade materna pode alterar os níveis de BDNF e a expressão da enzima desiodase do tipo III (D3) no cérebro dos filhotes, com consequente alteração dos níveis locais de T3 ao 7°, 10° e 16° dias de vida pós-natal. Os nossos resultados mostraram que a obesidade reduziu a expressão da D3 no 7º dia de vida pós-natal dos filhotes de mães obesas, mas não nos dias posteriores, sem alteração significativa nos níveis de BDNF. Não houve alteração significativa nos níveis de BDNF em nenhum dos dias avaliados. Os nossos dados sugerem que é possível que o hormônio tiroideano esteja envolvido nas alterações neurofisiológicas observadas em filhotes de ratas obesas.

Recentemente suspeitas de que mecanismos epigenéticos poderiam estar relacionados à fisiopatologia da depressão foram levantadas. Estudos recentes indicam que as alterações na transcrição gênica, induzidas por estresse ou por drogas antidepressivas, parecem envolver mecanismos epigenéticos. Nesse sentido, resultados preliminares de nosso grupo de pesquisa indicaram pioneiramente inibição global da metilação de DNA através da administração sistêmica do agente inibidor da DNA metiltransferase (DNMTs), 5-aza-2-deoxicitidina (5-azaD), induz efeito tipo-antidepressivo, dose-dependente, no modelo animal do nado forçado em ratos(Sales et al., 2011). O córtex pré-frontal medial ventral (CPFMv) é uma estrutura límbica intimamente relacionada com a neurobiologia da depressão. Evidências recentes indicam que o efeito tipo-antidepressivo aparece associado a aumento dos níveis da neurotrofina BDNF (brain derived neurotrophic factor) e de seu receptor TrkB no CPFMv, sendo a sinalização intracelular mediada pela ativação da proteína m-TOR. Contudo, não há evidências de que esses mecanismos moleculares estariam envolvidos nos efeitos induzidos pelos inibidores da metilação do DNA. Sabe-se, no entanto, que tanto o BDNF quanto TrkB têm sua expressão regulada por metilação do DNA. Diante disso, o objetivo presente trabalho será investigar a participação da via BDNF-TrkB-mTOR do CPFMv no efeito antidepressivo induzido por inibidores da metilação de DNA. Para tanto, ratos tratados com inibidores da metilação de DNA (5-azaD ou RG-108), em dois momentos diferentes (imediatamente após o PT e 23horas após o PT) foram submetidos ao teste do nado forçado (FST). Outro grupo de animais recebeu uma injeção intra-CPMv de k252a ou Rapamicina, 40 minutos antes do teste e uma injeção de BDNF intra-CPFMv, 30 minutos antes do teste. Em outro experimento, grupos independentes de animais submetidos ao nado forçado foram tratados sistemicamente com RG-108 e receberam injeção intra-CPFMv de K252a (antagonista de Trk) ou de rapamicina (inibidor da m-Tor), a fim de investigar se o efeito dessas drogas depende da via BDNF-TrkB-mTOR no CPFMv. Um grupo independente foi tratado com RG108 e CPFM desses animais foi dissecado para posterior análise da expressão de BDNF, TrkB e m-TOR, bem como da metilação de DNA. O tratamento com RG108 e 5azaD sistêmico reduziu o tempo de imobilidade dos animais submetidos ao nado forçado nos dois tempo de administração. A administração intra-CPFMv de BDNF promoveu efeito antidepressivo no FST, e esse efeito foi bloqueado pela administração de k252a ou Rapamicina no CPFMv. No mesmo sentido, o efeito antidepressivo do RG108 sistêmico foi bloqueado pela administração intra-CPFMv de k252a ou Rapamicina. Entretanto, a medida dos níveis de metilação global no CPFMv não apresentou alteração como tratamento com RG108, e também não mostrou alteração nos níveis de BDNF presente no CPF. O tratamento com RG108 não alterou a expressão, bem como a ativação de TRkB e mTOR. Concluímos que os inibidores da metilação do DNA apresentam agudamente efeito tipo antidepressivo rápido, que necessita da funcionalidade integral da via BDNF-TRkB-mTOR. Entretanto, esse efeito parece não alterar a síntese e expressão das proteínas envolvidas nessa via no que diz respeito ao CPFmv. / Recent studies indicate that changes in gene transcription induced by stress or antidepressant drugs appear to involve epigenetic mechanisms. Accordingly, results of our research group pioneered indicated global inhibition of DNA methylation through systemic administration of an inhibitor of DNA methyltransferase (DNMTs), 5-aza-2-deoxycytidine (5-AzaD), induces antidepressant-like effect dose-dependent in the animal model of forced swimming in rats (Sales et al., 2011). The ventral medial prefrontal (vmPFC) cortex is a limbic structure closely related to the neurobiology of depression. Recent evidence indicates that the antidepressant-like effect appears associated with increased levels BDNF (Brain derived neurotrophic factor) and its receptor TrkB in vmPFC, and intracellular signaling mediated by activation of protein mTOR. However, there is no evidence that these molecular mechanisms are involved in the effects induced by inhibitors of DNA methylation. It is known, however, both as BDNF and TrkB expression is regulated by DNA methylation. Thus, the goal of this work is to investigate the role of BDNF-TRkB pathway mTOR-vmPFC in the antidepressant effect induced by inhibitors of DNA methylation. To this end, rats treated with inhibitors of DNA methylation (5-Azad or RG-108), at two different times (immediately after 23hours after the PT and PT) were subjected to the forced swim test (FST). Another group received an intra-vmPFC injection of K252a or Rapamycin 40 minutes before the test, and an injection intra-vmPFC of BDNF 30 minutes before the test. In another experiment, separate groups undergoing the forced swim were treated systemically with RG-108 and received intra-vmPFC of K252a (Trk antagonist) or injection of rapamycin (m-Tor inhibitors) in order to investigate the effect these drugs depends on BDNF-TrkB-mTOR pathway in vmPFC. A separate group was treated with RG108 and mPFC these animals were dissected for analysis of the expression of BDNF and TrkB m-TOR, as well as DNA methylation. The systemic treatment whit 5azaD and RG108 reduced the immobility time of rats subjected to FST administration in both time. The intra-vmPFC BDNF administration promoted antidepressant effect in the FST, and this effect was blocked by the administration of K252a or Rapamycin in vmPFC. Similarly, the antidepressant effect of systemic RG108 was blocked by intra-vmPFC of K252a or Rapamycin administration. However, the measurement of the levels of global methylation in CPFMv did not change as treatment with RG108, and also showed no change in the levels of BDNF present in the CPF. Treatment with RG108 did not alter the expression and activation of TrkB and mTOR. We conclude that inhibitors of DNA methylation present acutely antidepressant-like effect, it needs the full functionality of the BDNF-TrkB-mTOR pathway. However, this effect seems not to alter the synthesis and expression of proteins involved in this pathway at vmPFC.

O número de pessoas acometidas por doenças cérebro vasculares, entre as quais, o acidente vascular cerebral (AVC), constitui um cenário alarmante nos dias atuais, fato que pode estar associado ao aumento da longevidade. A recuperação funcional de pessoas com sequelas de AVC requer a aplicação de técnicas de reabilitação que se baseiam em princípios de neuroplasticidade; no entanto, pouco se sabe quais são os benefícios morfofuncionais resultantes de diferentes abordagens terapêuticas. O presente estudo, portanto, teve como objetivos analisar a concentração plasmática de BDNF antes e após tratamento de reabilitação de indivíduos com AVC e correlacionar com o polimorfismo Val66Met; identificar e comparar a frequência do polimorfismo Val66Met na população brasileira e em pessoas que sofreram AVC. Os procedimentos experimentais foram aprovados pelo Comitê de Ética em Pesquisa da EACH/USP. O estudo foi dividido em duas abordagens experimentais: (i) caracterização genotípica de pessoas com diagnóstico de AVC e sua relação com diferentes protocolos de reabilitação e com o BDNF plasmático e (ii) estudo genético populacional para caracterização da frequência do polimorfismo Val66Met na população brasileira. Participaram deste estudo indivíduos saudáveis dos estados de Alagoas, Rio Grande do Sul e São Paulo (n=1558) e pacientes com sequelas de AVC (n=54). A análise do BDNF plasmático foi realizada por meio do teste imunoenzimático de ELISA e somente os indivíduos submetidos à terapia robótica tiveram níveis aumentados de BDNF circulante. As análises do polimorfismo Val66Met foram realizadas utilizando a técnica de PCR-RFLP (HRM). Não houve associação entre o polimorfismo e os níveis plasmáticos de BDNF. As frequências genotípicas e alélicas do polimorfismo Val66Met dos indivíduos saudáveis e com AVC foram muito semelhantes. Os dados de gênero apontou aumento nos níveis de BDNF em mulheres, entretanto, a idade não interferiu nos níveis de BDNF. Considerando-se os resultados, podemos concluir que o polimorfismo não apresenta relação com a ocorrência de AVC e não interfere nos níveis plasmáticos de BDNF plasmático. No que concerne às técnicas de reabilitação, a terapia robótica pode ser mais efetiva para desencadear eventos de neuroplasticidade considerando o aumento de BDNF circulante após o tratamento. Através do estudo populacional foi possível verificar que o perfil da miscigenação mudou ao longo de três gerações analisadas e confirmamos a presença rara do polimorfismo em pessoas de cor/raça preta e indígena / The number of people affected by cerebrovascular diseases, including the stroke, is an alarming scenario nowadays, which may be associated with the increment of the longevity. Functional recovery of people with stroke sequelae requires the application of rehabilitation techniques based on principles of neuroplasticity, however, the knowledge about how the morphological and functional benefits of different therapeutic approaches is insipient. This study, therefore, aimed to analyze the plasma concentration of BDNF before and after rehabilitation program of patients with stroke and correlate with Val66Met polymorphism; to identify and to compare the frequency of Val66Met polymorphism in the Brazilian population and in the patients who have suffered strokes. The experimental procedures were approved by the Research Ethics Committee of EACH/USP. The study was divided into two experimental approaches: (i) genotypic characterization of people diagnosed with stroke and their relation to different rehabilitation protocols and plasma BDNF and (ii) populational genetic study to characterize the frequency of Val66Met polymorphism in the Brazilian population. The study included healthy individuals in the states of Alagoas, Rio Grande do Sul and São Paulo (n = 1558) and patients with stroke sequelae (n = 54). The analysis of plasma BDNF was performed by immunoenzymatic test ELISA, and only those individuals undergoing robotic therapy had increased levels of circulating BDNF. The analysis of the polymorphism Val66Met was performed using PCR-RFLP (HRM). There was no association between the polymorphism and the plasma levels of BDNF. The genotypic and allelic frequencies of the Val66Met polymorphism of healthy individuals and stroke were similar. The gender data showed an increase in BDNF levels in women, but age did not interfere with BDNF levels. Considering the results, we can conclude that the polymorphism is not related to the occurrence of stroke and does not affect the plasma levels of serum BDNF. As regards the rehabilitation techniques, robotic therapy may be more effective to trigger neuroplasticity events considering the increase of circulating BDNF after treatment. Through the study population was possible to verify that the profile of miscegenation has changed over the three generations examined and confirmed the presence of the rare polymorphism in black and indigenous people

Les hallucinations auditives (HA) sont présentes chez 70% à 80% des patients atteints de schizophrénie et sont résistantes aux traitements pharmacologiques dans environs 25% cas. Ces symptômes induisent une détresse importante chez les sujets et grèvent le pronostic. Dans ce travail, nous avons mis en avant des altérations cérébrales spécifiques aux HA chez des patients atteints de schizophrénie. Dans une première étude, en utilisant la méthode de DTI, nous avons montré que les patients atteints de schizophrénie avec HA ont une intégrité du faisceau arqué, supérieure à celle mesurée chez des patients atteints de schizophrénie sans HA. Dans une seconde étude, en utilisant la méthode de SRM, nous avons montré une augmentation de NAA, reflet du métabolisme neuronal, dans le cortex préfrontal dorsolatéral de l'hémisphère droit chez les patients atteints de schizophrénie avec HA comparé au CPFDL gauche et à des patients atteints de schizophrénie sans HA. Dans ces deux études, le taux de NAA du CPFDL droit et l'intégrité du faisceau arqué ont été associés à la sévérité des HA présentes chez les patients. Dans notre dernière étude, nous avons montré une association entre le taux de BDNF périphérique, marqueur de la plasticité neuronale, et le taux de NAA mesuré dans le CPFDL droit, chez les patients atteints de schizophrénie résistante. Ces résultats montrent qu'il existe une pathophysiologie spécifique des HA chez les patients atteints de schizophrénie et mettent en avant l'importance de stratifier les patients sur la base de leurs symptômes prédominants dans les futures études pathophysiologiques de la schizophrénie / Auditory hallucinations (AH) are present in 70% to 80% of patients with schizophrenia and are resistant to pharmacological treatments in 25% of cases. These symptoms induce significant distress in patients and predict a bad prognosis. In this work we have highlighted cerebral alterations specific to AH in patients suffer from schizophrenia. In a first study, using DTI method, we showed that patients with schizophrenia and AH have an arcuate fasciculus integrity, reflected by the measurement of fractional anisotropy (FA) greater than the one measured in patients with schizophrenia without AH. In a second study, using MRS method, we showed an increase of NAA level measured in the dorsolateral prefrontal cortex (DLPFC) in the right hemisphere in patients with schizophrenia and AH compared to the DLPFC in the left hemisphere and compared to patients with schizophrenia and without AH. Moreover, in these two studies we showed an association between AH severity and the arcuate fasciculus integrity in the left hemisphere and an association between AH severity and NAA levels in the right DLPFC. Finally, in our last study, we quantified BDNF levels using ELISA method and showed an association between peripheral BDNF level, a marker of neuronal plasticity, and NAA levels in the right DLPFC, marker of neuronal metabolism, in patients with treatment-resistant schizophrenia. These results show that there is a specific pathophysiology of AH in patients with schizophrenia and highlight the importance of stratifying patients on the basis of their predominant symptoms in future pathophysiological studies of schizophrenia

Les douleurs neuropathiques, celles qui sont provoquées par des lésions du système nerveux central ou périphérique, sont les plus difficiles à traiter du fait de leur résistance aux traitements antalgiques classiques. Les traitements utilisés aujourd’hui font appel à des classes thérapeutiques non spécifiquement ciblées sur la douleur, en particulier des antidépresseurs et des anticonvulsivants. Leur efficacité limitée ne repose en fait que sur des observations empiriques. Une meilleure connaissance des processus physiopathologiques sous-tendant les douleurs neuropathiques constitue un préalable à toute innovation thérapeutique, et c’est à cette fin que je me suis appliqué à développer deux modèles de douleurs neuropathiques chez le rat pour en étudier les caractéristiques comportementales, fonctionnelles, cellulaires et biochimiques. Le premier modèle visait à l’induction d’une douleur neuropathique centrale provoquée par la section complète de la moelle épinière au niveau thoracique (T8-T9) ; le second a consisté à injecter, directement au niveau spinal, par voie intrathécale (i.t.), le facteur neurotrophique BDNF (Brain Derived Neurotrophic Factor ; dont l’implication dans les voies de signalisation nociceptive est bien établie dans la littérature). Dans les deux cas, les conséquences pro-algiques de ces interventions ont été comparées à celles induites par la ligature unilatérale du nerf sciatique, qui constitue encore aujourd’hui un modèle classique, mais très imparfait, d’une douleur neuropathique périphérique. Dès le 2ème jour après la section spinale, et jusqu’au moins deux mois plus tard, les rats lésés présentent une forte allodynie mécanique (test des filaments de von Frey) dans le territoire cutané juste en avant de la lésion. Cet effet traduit bien une neuropathie centrale car il n’existe pas chez les rats « sham » qui ont subi l’intégralité de l’intervention chirurgicale à l’exception de la section spinale. L’allodynie mécanique est associée à une induction significative de l’expression (RTqPCR) de marqueurs de souffrance neuronale (ATF-3) et d’activation microgliale (OX-42, récepteurs P2X4, P2X7 et TLR4) et astrocytaire (GFAP), ainsi que du BDNF et de cytokines pro-inflammatoires (IL-1ß, IL-6, TNF-α), mais de façon plus transitoire, ceci dans les ganglions de racines dorsales et/ou la moelle épinière dorsale (comme à la suite de la ligature du nerf sciatique, mais avec des cinétiques différentes). Pour sa part, l’injection intrathécale i.t. d’une dose infra-nanomolaire unique de BDNF (0.3 – 3.0 ng) induit aussi une forte allodynie et une hyperalgésie mécaniques, au niveau des pattes postérieures, qui se développent en 3-5 jours, et perdurent pendant deux semaines. Cependant, au contraire de la section spinale (et de la ligature du nerf sciatique), l’injection i.t. de BDNF ne provoque pas d’activation microgliale ni d’induction de cytokines. Elle entraine en revanche une auto-induction du BDNF, qui semble clé pour l’hyperalgésie puisque celle-ci peut être, en grande partie, supprimée par l’administration d’un inhibiteur du récepteur TrkB du BDNF, la cyclotraxine B (20 mg/kg i.p.), comme d’ailleurs l’hyperalgésie induite par la ligature du nerf sciatique. Au plan pharmacologique, un antalgique opiacé comme le tapentadol s’est révélé efficace dans les deux modèles. De même, les anticonvulsivants, comme la prégabaline et la gabapentine, ont réduit la douleur neuropathique chez les rats injectés par le BDNF i.t. et chez les rats CCI-SN. En conclusion, il semble que l’injection intrathécale de BDNF, qui évite la réalisation de lésions par intervention chirurgicale, puisse constituer un nouveau modèle pertinent de douleur neuropathique chez le rat. De plus, nos résultats laissent à penser que le blocage de la voie de signalisation BDNF-TrkB pourrait ouvrir de nouvelles pistes pour la réduction des douleurs neuropathiques périphériques. (...) / Neuropathic pain, caused by lesions of central or peripheral nervous system, is difficult to treat because of its resistance to classical antalgic treatments. Most of pharmacotherapeutic treatments of neuropathic pain (antidepressants, anticonvulsants) currently used are only based on empirical data and are not specifically aimed at relieving pain. Better knowledge of the mechanisms underlying neuropathic pain is an absolute prerequesite to develop new and innovative treatments. With the aim of contributing to elucidate these mechanisms, I developed two models of neuropathic pain in rats, and studied their behavioral, pharmacological, cellular and biochemical characteristics. The first model consisted of the induction of central neuropathic pain by complete transection of the spinal cord at T8-T9 level. The second one consisted of the administration of BDNF (Brain Derived Neurotrophic Factor; which implication in nociceptive signaling pathways is well established in the literature), directly at the spinal level, via intrathecal (i.t.) injection. In both cases, pro-algesic consequences of these interventions have been compared to those induced by unilateral ligation of the sciatic nerve, which is still considered as a classical, although not really satisfactory, model of peripheral neuropathic pain. From the second day after spinal cord transection up to (at least) 2 months later, lesioned rats developed a strong mechanical allodynia (von Frey filaments test) within a limited cutaneous territory just rostral to the surgical scar. This effect really reflected central neuropathic pain because it did not occur in control, « sham operated » animals, that underwent the same surgical intervention except the spinal cord transection. Mechanical allodynia was associated with marked overexpression of markers of neuronal injury (ATF-3), microglial activation (OX-42, P2X4, P2X7 and TLR4 receptors), astrocyte activation (GFAP), as well as upregulation of transcripts encoding BDNF and pro-inflammatory cytokines (IL-1ß, IL-6 and TNF-α, but only transiently for the latter cytokine), in dorsal root ganglia and/or spinal cord. Therefore, spinal cord transection triggered a strong neuroinflammatory reaction, like that occurring after peripheral nerve lesion, but with different time course and amplitude. On the other hand, intrathecal injection of an infra-nanomolar dose of BDNF (0.3 – 3.0 ng) also induced a strong mechanical allodynia and hyperalgesia at hindpaw level, which developed within 3-5 days and lasted for at least two weeks. However, in sharp contrast with spinal cord transection (and sciatic nerve ligation), i.t. injection of BDNF did not induce any microglial activation and/or proinflammatory cytokines upregulation. Intrathecal (exogenous) BDNF-induced (endogenous) BDNF auto-induction might play a key role in the maintenance of i.t. BDNF-induced hyperalgesia as the latter can be reversed by pharmacological blockade of the BDNF receptor TrkB (with cyclotraxin B at 20 mg/kg i.p., which also reversed sciatic nerve ligation-induced hyperalgesia). Pharmacological investigations showed that the opioid antalgic drug tapentadol and anticonvulsants such as pregabalin and gabapentin efficiently reduced neuropathic pain in i.t. BDNF i.t. as well as in sciatic nerve-ligated rats. Accordingly, intrathecal injection of BDNF might represent a new non-surgical model of neuropathic pain in rats. Moreover, our results indicate that blockade of BDNF-TrkB signaling could open new therapeutic perspectives for alleviating peripheral neuropathic pain. This innovative pharmacological approach should also be explored in the case of central neuropathic pain caused by spinal cord injury.

Le « Brain-Derived Neurotrophic Factor » (BDNF) est la neurotrophine la plus abondante et la plus répandue dans le cerveau humain. De nombreuses études se sont intéressées à son rôle dans la survie neuronale, la croissance et la plasticité synaptique. La signalisation BDNF est dépendante de deux récepteurs, le récepteur tyrosine kinase (TrkB) et le récepteur neurotrophine p75 (p75NTR). Il est bien établi que le rôle trophique du BDNF est assuré via son récepteur de haute-affinité TrkB, alors que la forme précurseur proBDNF active p75NTR vers la voie d'apoptose. Cette double signalisation est physiologiquement contrôlée par un équilibre entre les différentes voies. Les résultats obtenus à partir des études cliniques et des modèles animaux suggèrent un rôle de la signalisation BDNF dans les tauopathies, caractérisées par l'existence de dépôts intracérébraux de protéine tau, une caractéristique commune à certaines maladies neurodégénératives, notamment la maladie d'Alzheimer (MA). Cependant, aucune investigation n'a été menée jusqu'à présent sur les modifications que pouvaient induire les tauopathies dans la signalisation BDNF et si une dérégulation de l'expression du BDNF pouvait affecter ses propres récepteurs TrkB et p75NTR.Dans ce travail de thèse, nous avons utilisé une lignée de poisson-zèbre transgénique portant la mutation humaine TAUP301L retrouvée notamment dans le démence fronto-temporale. Nous avons mesuré l'expression de BDNF et de ses deux récepteurs au niveau transcriptionnel et protéique. Nous n'avons observé aucune modification des taux d'expression de BDNF et de TrkB, en revanche, nous avons noté une augmentation significative de p75NTR. A l'aide de la même lignée transgénique, nous avons induit une baisse d'expression de BDNF via la micro-injection de morpholinos. De manière remarquable, la baisse d'expression de BDNF affecte de façon différentielle TrkB et p75NTR. En effet, nous avons observé une diminution de l'expression de TrkB et parallèlement une augmentation de p75NTR. De plus, la baisse d'expression de BDNF aggrave la neurotoxicité associée au développement de la tauopathie ce qui se traduit par une augmentation de la mort neuronale et de l'hyperphosphorylation de tau, cette dernière étant concommittante à une activation de la Glycogen Synthétase Kinase 3 beta (GSK3beta).Une diminution de l'effet neuroprotecteur de BDNF à travers un déséquilibre de ces récepteurs de signalisation a été également montré en étudiant le rôle de BDNF au cours du développement de la ligne latérale postérieure (PLL). Ce système est considéré comme un modèle d'étude particulièrement pertinent pour évaluer différents processus biologiques comme la migration cellulaire collective ou la régénération cellulaire. Nous avons détecté l'expression de BDNF dans plusieurs structures de la PLL. La diminution d'expression de BDNF conduit à un défaut de migration du primordium de la PLL, associé à une augmentation de la mort cellulaire. De plus, nous avons observé une réduction de la prolifération cellulaire et un défaut de repousse axonale du nerf, ce qui conduit à des anomalies de régénération à la fois du nerf de la PLL et des cellules ciliées. Nos résultats suggèrent que le BDNF joue un rôle essentiel au cours du développement de la PLL et démontrent la pertinence du système de la ligne latérale en tant que modèle d'étude des fonctions de BDNF.En conclusion, notre étude représente la première analyse du rôle in vivo de BDNF et de ses 2 récepteurs de signalisation. Nous avons ainsi montré les répercussions d'une dérégulation des voies de signalisation du BDNF. Un équilibre entre ces deux voies est essentiel pour le développement et la survie cellulaire, ce qui fait de BDNF non seulement une cible thérapeutique potentielle, mais également une neurotrophine clé pouvant activer plusieurs circuits de signalisation, potentialisant ainsi son rôle protecteur. / Brain-derived neurotrophic factor (BDNF) is the most abundant secreted and widely distributed neurotrophin in human brain. It has been extensively studied for its role in neuronal survival, growth and synaptic plasticity. BDNF signaling mediated through tryosine receptor kinase B (TrkB) and p75NTR neurotrophin receptor (p75NTR). It is well established that BDNF beneficial actions are mediated by it is high-affinity TrkB, whereas pro-BDNF activates p75NTR towards apoptosis. This diverse dual signaling is normally under a tight balance regulation. Based on clinical and animal studies, it has been suggested that BDNF signaling is involved in tauopathy, which is a pathological hallmark in several neurodegenerative diseases, including Alzheimer's disease (AD). However, what changes tauopathy may induce on BDNF signaling, and whether BDNF deregulation could affect its two signaling receptors (TrkB, p75NTR), and eventually tauopathy pathogenesis, have not been investigated. In this study we used a transgenic zebrafish line for human Tau-P301L tauopathy, and measured transcriptional and protein levels of BDNF and of its two signaling receptors. We found no modification of BDNF and TrkB expression levels, but a significant up-regulation of p75NTR. We then used the same transgenic line to generate BDNF knockdown using morpholino microinjection technique. Interestingly, BDNF knockdown differentially affects TrkB and p75NTR; we observed a reduction of TrkB expression and an increase in p75NTR expression. In addition, BDNF knockdown aggravates tauopathy-associated toxicity; we found an increase in neuronal cell death and tau hyperphosphorylation, the latter was accompanied by an activation of tau glycogen synthase kinase 3beta (GSK3beta). Attenuation of BDNF neuroprotective effects through imbalance of its signaling receptors was further highlighted through studying BDNF role in the development of zebrafish posterior lateral line system (PLL). This system has recently emerged as a powerful tool to study several dynamic biological processes, including collective cell migration and nerve/hair cells regeneration. We detected BDNF expression in different PLL components. BDNF knockdown led to an impairment of the PLL primordium migration due to concomitant increase in cell death rate. In addition, reduced cell proliferation and defect in axonal re-growth were observed , which led to major defects of PLL nerve/hair cells regeneration, respectively. These findings suggest that BDNF has an essential role in PLL development, but more important they introduce PLL as research model to study BDNF functions. This is the first study to provide a detailed in vivo analysis of BDNF and its two signaling receptors. Our findings highlight several implications of BDNF signaling deregulation. Balanced signaling clearly has essential roles in survival and development, in addition to being a therapeutic target, BDNF can itself activate diverse molecular pathways, thus setting up a potential circuitry that could enhance its protective role.

Les récepteurs purinergiques P2X sont des canaux ioniques activés par l’ATP. Ils sont exprimés très largement dans l’organisme, et possèdent de nombreux rôles physiologiques et pathologiques. Les récepteurs P2X4 en particulier ont été impliqués dans les processus de douleur chronique. Suite à une lésion nerveuse, l’expression des récepteurs P2X4 est induite de novo dans la microglie spinale activée, où ils sont responsables de l’hypersensibilité mécanique caractéristique des douleurs neuropathiques.Notre étude montre que les récepteurs P2X4 neuronaux sont également des acteurs centraux dans plusieurs processus pathologiques, et notamment dans la douleur inflammatoire périphérique chronique. Les récepteurs P2X4 sont exprimés par les neurones sensoriels des ganglions rachidiens et semblent impliqués dans la libération du BDNF dans la corne dorsale de la moëlle épinière. Cette libération conduit à l’activation des voies de signalisation de la voie BDNF/TrkB, et en particulier à la diminution de l’expression de KCC2. Ce processus est en partie responsable de l’allodynie tactile et de l’hyperalgésie mécanique observée en cas de douleur inflammatoire chronique. Notre étude a également permis d’étendre cette hypothèse à un modèle d’excitotoxicité in vitro dans l’hippocampe, mimant une activité épileptiforme. Nos résultats indiquent que les récepteurs P2X4 neuronaux pourraient être des acteurs importants de la libération de BDNF dans l’hippocampe lors d’un évènement excitotoxique. / Purinergic receptors P2X are ATP-gated ion channels widely expressed in the organism and involved in many physiological and pathological states. Particularly, P2X4 receptors have been involved in chronic pain. Following nerve injury, their expression is induced de novo in activated spinal cord microglia where they are responsible for the BDNF release leading to tactile allodynia, a characteristic of neuropathic pain. Our study shows that neuronal P2X4 receptors are crucial actors of other pathological processes, including inflammatory pain. We show that P2X4R are expressed in sensory neurons in dorsal root ganglions and seem involved in BDNF release in the spinal cord. This release leads to activation of BDNF/TrkB signalization pathways, and particularly to the downregulation of KCC2. This process underlies the spinal hyperexcitability in chronic inflammatory pain states. These results have been extended to model of excitotoxicity in the hippocampus mimicking the lesions caused by an epileptic activity. Our preliminary results suggest that neuronal P2X4 receptors are likely major actors in the BDNF release in the hippocampus following an excitotoxicitic insult.