Alta prevalência, farmacorresistência e bom prognóstico cirúrgico são algumas das características clínicas que tornam a epilepsia do lobo temporal mesial com esclerose hipocampal (ELTM-EH) uma das mais importantes formas de epilepsia. Ela é o modelo da epilepsia cirurgicamente curável. Infelizmente, cerca de 10% dos pacientes evoluem com resultado cirúrgico insatisfatório. A ELTM-EH está associada a alterações amplas do perfil de expressão dos microRNAs (miRNAs) do hipocampo. Recentemente, constatou-se a existência de miRNAs estáveis no sangue periférico e em outros fluidos corporais, comprovadamente aplicáveis como biomarcadores, cuja abrangência vai do diagnóstico à resposta terapêutica. Tendo isso em vista, a pesquisa partiu do seguinte questionamento: é possível a identificação, no sangue periférico, de assinaturas moleculares por miRNAs que predigam o resultado do tratamento cirúrgico da ELTM-EH? Por meio de técnicas de biologia molecular, avaliaram-se amostras de sangue e hipocampo de pacientes submetidos à lobectomia temporal anterior em consequência de ELTMEH farmacorresistente. As amostras eram representativas de indivíduos com resultado cirúrgico favorável (Engel IA) e desfavorável (Engel III e IV). Com a técnica de microarray obteve-se o perfil de expressão de miRNAs das amostras triadas e chegou-se a um conjunto de seis miRNAs candidatos a biomarcadores de prognóstico cirúrgico: miR-92b-3p; miR-1238-3p; miR-1181; miR-636; miR- 1229-3p e miR-486-5p. Em seguida, com a técnica de PCR em tempo real, quantificou-se a expressão destes seis miRNAs e, a partir da otimização de um ponto de corte na escala de expressão, cada miRNA circulante foi apreciado como preditor de resultado cirúrgico. Assim, constatou-se hiperexpressão sanguínea dos seis miRNAs, sem distinção estatística entre os grupos Engel IA e Engel III-IV, hiperexpressão hipocampal do miR-486-5p no grupo Engel IA e hipoexpressão hipocampal do miR-636 nos grupos Engel IA e Engel III-IV. Na análise dos miRNAs circulantes como preditores de sucesso cirúrgico, o miR- 1238-3p exibiu uma sensibilidade de 40,00%, especificidade de 92,86% e acurácia de 65,52%. O conjunto miR-1238/miR1181 mostrou sensibilidade de 46,67%, especificidade de 85,71% e acurácia de 65,52%. O único miRNA circulante sondado como preditor de insucesso cirúrgico, o miR-636, revelou sensibilidade de 21,43%, especificidade de 93,33% e acurácia de 58,62% / A high prevalence, drug resistance and good surgical prognosis are some of the clinical characteristics that cause mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS) to be one of the most important forms of epilepsy. This condition is the model of surgically curable epilepsy, although unfortunately about 10% of the patients exhibit an unsatisfactory surgical outcome. MTLE-HS is associated with extensive changes in the expression profile of hippocampal microRNAs (miRNAs). It has been recently observed that stable miRNAs exist in peripheral blood and in other body fluids which have been proved to be applicable as biomarkers from diagnosis to therapeutic response. On this basis, the present investigation was based on the following question: is it possible to identify molecular signatures by peripheral blood miRNAS that predict the outcome of surgical treatment of MTLE-HS? Molecular biology techniques were used to evaluate blood and hippocampal samples of patients submitted to anterior temporal lobectomy as a consequence of drug-resistant MTLE-HS. The samples were representative of patients with a favorable (Engel IA) and unfavorable (Engel III and IV) surgical outcome. The microarray technique was used to obtain the expression profile of miRNAs in the samples, with a set of six miRNAs being reached as candidate biomarkers for surgical prognosis: miR-92b-3p, miR-1238- 3p, miR-1181, miR-636, miR-1229-3p, and miR-486-5p. Next, real-time PCR was used to quantitate the expression of these six miRNAs and, based on the optimization of a cut-off point on the expression scale, each circulating miRNA was evaluated as surgical outcome predictor. We observed blood hyperexpression of the six miRNAs with no significant difference between the Engel IA and Engel IIIIV groups, hippocampal hyperexpression of miR-486-5p in the Engel IA group, and hippocampal hypoexpression of miR-636 in the Engel IA and Engel III-IV groups. Analysis of circulating miRNAs as predictors of surgical success revealed that miR-1238-3p exhibited 40.00% sensitivity, 92.86% specificity and 65.52% accuracy. The miR-1238/miR1181 set showed 46.67% sensitivity, 85.71% specificity and 65.52% accuracy. The only circulating miRNA evaluated as a predictor of surgical failure, miR-636, showed 21.43% sensitiviy, 93.33% specificity, and 58.62% accuracy

O consumo mundial de cocaína vem crescendo e no Brasil já são estimados mais de 2 milhões de usuários, destes 370 mil usam regularmente o crack. A cocaína, em suas diversas formas, é um psicoestimulante com alto potencial de abuso e a forma fumada causa à seus usuários mais complicações de saúde do que as demais formas. Muitas dessas complicações estão relacionadas às funções cognitivas, como comprometimento da atenção e memória. O usuário de crack, no ato de fumar, está sujeito tanto à ação da cocaína volatilizada quanto a dos seus produtos de pirólise, principalmente da anidroecgnonina metil éster (AEME). Considerando que pouco se conhece a respeito da AEME, ou de sua associação com cocaína, que os distúrbios cognitivos podem estar relacionados à morte neuronal e que o hipocampo é uma das principais estruturas encefálicas relacionada com cognição e memória, este trabalho visou investigar as vias de ativação de morte celular decorrente das exposições à 1 mM de AEME, 2 mM de cocaína, bem como da associação de ambas (C + A), por 3, 6 e 12 h. Para tanto, utilizamos neurônios hipocampais de embriões de rato no 18º dia embrionário (E18) que foram mantidos em cultura por até 7 dias (DIV7), quando foram feitas as exposições. Nossos resultados mostraram que em 3 h a cocaína e a AEME promoveram aumento de atividade enzimática (pelo teste de MTT) que se reverteu ao longo de 12 h. Além disso, AEME aumentou na permeabilidade da membrana plasmática em 6 h que se manteve em 12 h. Embora essas alterações tenham ocorrido em 3 h e 6 h, caspase-8 se ativou apenas em 12 h, ativando também a sinalização apoptótica com a externalização de FS. A cocaína ativou o processo autofágico a partir de 3 h aumentando a quantificação de LC3 II, mas apresentou redução de células com vesículas ácidas em 6 h e 12 h, sugerindo que esta promova morte neuronal por causar falha no fluxo autofágico. A AEME apresentou somente aumento de células com vesículas ácidas em 3 h, revertendo-se já em 6 h, indicando que o processo autofágico só se fez presente no primeiro horário, dando vez à programação de apoptose celular, por ativação da via extrínseca. A associação dessas substâncias apresentou-se mais neurotóxica do que as substâncias isoladas, com redução de células íntegras a partir de 3 h de exposição, ativação de caspase-8 e externalização de FS em 6 h, sem envolver o sistema autofágico. Além disso, as características morfológicas observadas em 6 h, como o aumento do tamanho do núcleo e do corpo celular que se tornaram picnóticos em 12 h, podem sugerir que a neurotoxicidade induzida por C + A seja por necroptose, onde a ativação de caspases resulta em um processo tipo necrótico. Assim, concluímos que, embora a literatura mostre morte neuronal por apoptose a partir de 24 h de exposição para cocaína e para AEME, as respostas celulares que levam à este fim iniciam-se já em 12 h, por ativação da via extrínseca e a associação destas substâncias é ainda mais neurotóxica, iniciando a sinalização de morte já em 6 h e induzindo uma morfologia tipo necrótica. / Cocaine market is increasing all around the world. In Brazil it is estimated that almost 2 million people make usage of this substance which 370 thousand people use the crack form. Cocaine is a psychostimulant with large potential for abuse and the smokable form produces more health problems than the other routes of use, mainly in the cognitive field related to compromising attention, memory and decision take. The crack users are exposed to both volatized cocaine and their pyrolysis products, which the main product is the anhydroecgonine methyl ester (AEME). Considering that the cognitive disturbs could be related to neurons death, the memory functions are also related to the hippocampal functions, and little is known about the AEME neurotoxicity or even the combination of cocaine and AEME in cell fate, our study aims to characterize the time and pathways related to the hippocampal neurotoxicity induced by 2 mM of cocaine, 1 mM of AEME and the association (C + A) of both substances during 3 h, 6 h and 12 h of exposure. Our results showed that cocaine and AEME increased enzymatic activity (MTT test) in 3 h but it reversed during 12 h of exposure. Moreover, AEME increased cell permeability in 6 h keeping it until 12 h. Although theses early alterations, both substances activated caspase -8 after 12 h when early apoptosis was also observed by the FS externalization. Cocaine activated the autophagic process at 3 h increasing the LC3 II quantification, but decreased the number of cell with acid vesicle at 6 h and 12 h, suggesting neuronal death due to failure in the autophagic flux. AEME showed increased in cell number with acid vesicle only in 3 h which returned after 6 h suggesting that the autophagic process gave place to the apoptotic program starting from the extrinsic pathway. The association of cocaine and AEME was shown more neurotoxic than them alone, decreasing the number of integral cells after 3 h, activating caspase -8 and promoting FS externalization after 6 h without involving the autophagy. In addition, taking the C + A morphology in 6 h, where it was observed increasing of nucleus and soma size that became pyknotic at 12 h, we suggest that the neuronal death could occur by necroptosis because this composition activated caspase -8 and resulted in necrotic like morphology. Thus, we conclude that cocaine- and AEME-induced apoptosis neuronal death starts in 12 h of exposure by the extrinsic pathway and the association of both substances is more neurotoxic than they alone, starting earlier after 6 h and resulting in a necrotic-like morphology.

Leung, Kin Ling. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 133-162). / Abstracts in English and Chinese. / CONTENTS --- p.i / ACKNOWLEDGEMENTS --- p.ii / ABBREVIATIONS --- p.iii / ABSTRACT --- p.vi / 論文摘要 --- p.ix / Chapter CHAPTER 1 --- INTRODUCTION --- p.1 / Chapter 1.1 --- Obstructive sleep apnea syndrome --- p.1 / Chapter 1.1.1 --- Symptoms of OSA --- p.2 / Chapter 1.1.2 --- Causes of OSA --- p.5 / Chapter 1.1.3 --- Complications of OSA --- p.6 / Chapter 1.1.4 --- Episodic hypoxia profile --- p.9 / Chapter 1.2 --- Hippocampus --- p.12 / Chapter 1.2.1 --- General structure of hippocampus --- p.12 / Chapter 1.2.2 --- The neuronal circuitry of hippocampus --- p.17 / Chapter 1.2.3 --- Cell types of hippocampus --- p.21 / Chapter 1.2.4 --- Functions of hippocampus --- p.24 / Chapter 1.3 --- Memory Formation and long term potentiation --- p.27 / Chapter 1.4 --- Neurotrophins --- p.33 / Chapter 1.5 --- Brain-derived neurotrophic factor (BDNF) --- p.38 / Chapter 1.5.1 --- Molecular characteristics of BDNF --- p.38 / Chapter 1.5.3 --- Functions of BDNF --- p.46 / Chapter 1.5.4 --- BDNF and neuronal plasticity --- p.46 / Chapter 1.6 --- Tissue plasminogen activator - plasmin system --- p.51 / Chapter 1.6.1 --- Molecular characteristics of tissue plasminogen activator - plasmin system --- p.51 / Chapter 1.6.2 --- Functions of tissue plasminogen activator - plasmin system --- p.54 / Chapter 1.7 --- Aim of the study --- p.59 / Chapter CHAPTER 2 --- MATERIALS AND METHODS --- p.61 / Chapter 2.1 --- Animal model of obstructive sleep apnea --- p.61 / Chapter 2.1.1 --- Intermittent hypoxia --- p.61 / Chapter 2.2 --- Electrophysiological recordings --- p.65 / Chapter 2.2.1 --- Preparation of brain slices --- p.65 / Chapter 2.2.1 --- Visualization of hippocampus CA1 Neurons --- p.66 / Chapter 2.2.3 --- Patch-clamp recordings --- p.66 / Chapter 2.3 --- Protein analysis - ELISA --- p.71 / Chapter 2.3.1 --- Isolation of mouse hippocampus total protein --- p.71 / Chapter 2.3.2 --- ELISA --- p.72 / Chapter 2.3 --- Protein analysis (II) - Western blot --- p.74 / Chapter 2.4.1 --- Isolation of mouse hippocampus total protein --- p.74 / Chapter 2.4.2 --- Western blot analysis --- p.75 / Chapter 2.5 --- Data analysis --- p.78 / Chapter CHAPTER 3 --- RESULTS --- p.79 / Chapter 3.1 --- Effect of intermittent hypoxia on passive and active properties of hippocampal CA1 neurons --- p.79 / Chapter 3.1.1 --- Passive properties --- p.79 / Chapter 3.1.2 --- Membrane excitability --- p.83 / Chapter 3.1.3 --- Action potential characteristics --- p.93 / Chapter 3.2 --- Effect of intermittent hypoxia on the expression of BDNF and related proteins --- p.104 / Chapter 3.2.1 --- "Levels of total BDNF, NGF, NT-3 and NT-4/5" --- p.104 / Chapter 3.2.2 --- Recovery study of the expression of BDNF after IH treatment --- p.110 / Chapter 3.2.3 --- Differential effect of IH on pro-BDNF and mature BDNF --- p.114 / Chapter 3.2.4 --- "Expressions of tissue plasminogen activator, plasmin and plasminogen" --- p.117 / Chapter Chapter 4 --- Discussion --- p.121 / Chapter 4.1 --- Changes in neuronal excitability of CA1 neurons under intermittent hypoxia --- p.121 / Chapter 4.2 --- Intermittent hypoxia-induced changes in BDNF level --- p.127 / Chapter 4.3 --- Conclusion --- p.130 / REFERENCES --- p.133

Ho, Tsz Wan. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 125-165). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (leaves 67-80).

Post-traumatic stress disorder (PTSD), an anxiety disorder, may develop after experiencing or witnessing a severe traumatic event. Characteristic symptoms include hyper arousal and amnesic symptoms, while volume reductions in the hippocampus of these patients appear correlated with illness severity and the degree of cognitive deficit. Stress-induced increases in plasma cortisol have been implicated in this apparent atrophy of the hippocampus, although, clinical studies have described a marked suppression of plasma cortisol in PTSD. Given this hypocortisolemia, the basis for hippocampal neuro degeneration and cognitive decline remains unclear. While stress-related hippocampal structural changes have been linked to the neurotoxic effects of glucocorticoids and glutamate. NMDA-NO pathways have been found to play a causal role in anxiety-related behaviours. Prior exposure to trauma is an important risk factor for PTSD. In most instances the disorder becomes progressively worse over time, possibly with a delayed onset, suggesting a role for sensitization. In this study a time-dependent sensitization (TDS) model was used to induce PTSD-like sequelae in male Spraque-Dawley rats. The TDS-model is based on exposure to acute stressors, with a reminder of the trauma, in the form of re-exposure to one of the acute stressor, seven days later. NOS-activity, NMDA receptor parameters (Bmax and Kd) and GABA levels in the hippocampus of rats, as well as plasma corticosterone levels were determined 21 days after exposure to the TDS-model. Increased levels of corticosterone were measured after exposure to acute stress, but these levels were found to decrease below basal levels 21 days after the re-exposure, thus mimicking glucocorticoid levels in patients with PTSD. These findings may also imply that the increase in glucocorticoid levels after stress exposure is only the initial step in a cascade of events leading to neuronal damage in the hippocampus. This study also found that stress-restress evoked a long-lasting increase in hippocampal NOS activity that was accompanied by a reactive down-regulation of hippocampal NMDA receptors and dysregulation of inhibitory GABA pathways. Subsequently, animals were chronically treated with certain pharmacological agents prior to exposure to the TDS-model to determine possible approaches for inhibiting the induction of PTSD. Pre-treatment with fluoxetine, currently indicated in the treatment of PTSD. and the nNOS inhibitor, 7-nitroindazole, had no effect on the increased NOS activity measured 21 days afler exposure to the TDS-model. Pre-treatment with the iNOS inhibitor, aminoguanidine, however, resulted in inhibition of the observed increase in hippocampal NOS-activity, implicating a possible role for the iNOS isoform in the etiology of PTSD. Treatment with ketoconazole, an inhibitor of glucoccfticoid synthesis, resulted in inhibition of the increase in NOS-activity observed after exposure to TDS-stress, thus indicating a possible link between stress glucocorticoid-release and NO synthesis. These perturbations may have importance in explaining the increasing evidence for stress-related hippocampal degenerative pathology and cognitive deficits seen in patients with PTSD. Uncovering and understanding the role of NO in PTSD will hopefully lead to the development of selective therapeutic agents in disorders like PTSD. as well as providing a better understanding of basic processes underlying normal and pathological neuronal functions in PTSD. / Thesis (Ph.D. (Pharmacology))--North-West University, Potchefstroom Campus, 2004.

Post-traumatic stress disorder (PTSD), an anxiety disorder, may develop after experiencing or witnessing a severe traumatic event. Characteristic symptoms include hyper arousal and amnesic symptoms, while volume reductions in the hippocampus of these patients appear correlated with illness severity and the degree of cognitive deficit. Stress-induced increases in plasma cortisol have been implicated in this apparent atrophy of the hippocampus, although, clinical studies have described a marked suppression of plasma cortisol in PTSD. Given this hypocortisolemia, the basis for hippocampal neuro degeneration and cognitive decline remains unclear. While stress-related hippocampal structural changes have been linked to the neurotoxic effects of glucocorticoids and glutamate. NMDA-NO pathways have been found to play a causal role in anxiety-related behaviours. Prior exposure to trauma is an important risk factor for PTSD. In most instances the disorder becomes progressively worse over time, possibly with a delayed onset, suggesting a role for sensitization. In this study a time-dependent sensitization (TDS) model was used to induce PTSD-like sequelae in male Spraque-Dawley rats. The TDS-model is based on exposure to acute stressors, with a reminder of the trauma, in the form of re-exposure to one of the acute stressor, seven days later. NOS-activity, NMDA receptor parameters (Bmax and Kd) and GABA levels in the hippocampus of rats, as well as plasma corticosterone levels were determined 21 days after exposure to the TDS-model. Increased levels of corticosterone were measured after exposure to acute stress, but these levels were found to decrease below basal levels 21 days after the re-exposure, thus mimicking glucocorticoid levels in patients with PTSD. These findings may also imply that the increase in glucocorticoid levels after stress exposure is only the initial step in a cascade of events leading to neuronal damage in the hippocampus. This study also found that stress-restress evoked a long-lasting increase in hippocampal NOS activity that was accompanied by a reactive down-regulation of hippocampal NMDA receptors and dysregulation of inhibitory GABA pathways. Subsequently, animals were chronically treated with certain pharmacological agents prior to exposure to the TDS-model to determine possible approaches for inhibiting the induction of PTSD. Pre-treatment with fluoxetine, currently indicated in the treatment of PTSD. and the nNOS inhibitor, 7-nitroindazole, had no effect on the increased NOS activity measured 21 days afler exposure to the TDS-model. Pre-treatment with the iNOS inhibitor, aminoguanidine, however, resulted in inhibition of the observed increase in hippocampal NOS-activity, implicating a possible role for the iNOS isoform in the etiology of PTSD. Treatment with ketoconazole, an inhibitor of glucoccfticoid synthesis, resulted in inhibition of the increase in NOS-activity observed after exposure to TDS-stress, thus indicating a possible link between stress glucocorticoid-release and NO synthesis. These perturbations may have importance in explaining the increasing evidence for stress-related hippocampal degenerative pathology and cognitive deficits seen in patients with PTSD. Uncovering and understanding the role of NO in PTSD will hopefully lead to the development of selective therapeutic agents in disorders like PTSD. as well as providing a better understanding of basic processes underlying normal and pathological neuronal functions in PTSD. / Thesis (Ph.D. (Pharmacology))--North-West University, Potchefstroom Campus, 2004.

Introdução: Perda de memória é um dos sintomas mais comuns em pacientes nos estágios iniciais da doença de Alzheimer; esses déficits são um reflexo do envolvimento da formação do hipocampo. O BDNF tem sido relacionado com a plasticidade do hipocampo. Neste sentido, as combinações de biomarcadores, como, por exemplo, a volumetria do hipocampo, pode apresentar um maior valor preditivo para diferenciar doença de Alzheimer do envelhecimento normal em pacientes com comprometimento cognitivo leve. Objetivo: A presente tese de doutorado teve como objetivo avaliar os níveis séricos do BDNF e o volume do hipocampo em pacientes com demência devido à doença de Alzheimer, Comprometimento Cognitivo Leve (CCL) e idosos saudáveis. Métodos: Para realização do estudo foram selecionados 10 idosos saudáveis, 10 CCL e 13 pacientes com demência devido à doença de Alzheimer pelos critérios NIA-AA. Todos participantes foram submetidos a uma avaliação cognitiva. Para as análises do BDNF, foi utilizado método de ELISA e para as análises de volumetria do hipocampo as imagens foram obtidas por meio de equipamento de ressonância de 1.5T e os volumes obtidos por meio do programa NeuroQuant®. Resultados: Idosos saudáveis apresentaram níveis séricos mais elevados de BDNF do que os CCL e pacientes com demência. O grupo de pacientes com demência apresentou menor volume total do hipocampo do que os idosos saudáveis e os CCL. Não houve correlação significativa do BDNF sérico com volume do hipocampo. Conclusão: Considerando nossos resultados em conjunto (baixos níveis de BDNF nos grupos CCL e demência devido à DA e menor volume do hipocampo na demência devido à AD), podemos supor que a diminuição dos níveis de BDNF ocorre antes da lesão neuronal expressa pela redução do hipocampo. / Introduction: Memory impairment is the most common symptom in patients in the early stages of Alzheimer's disease; this deficit is a reflection of the involvement of the hippocampal formation. BDNF has been linked to the hippocampal plasticity. Combinations of biomarkers, such as the hippocampal volumetry may have higher predictive value for differentiating Alzheimer's disease from normal aging in patients with mild cognitive impairment. Objective: The objective of present thesis was to evaluate serum levels of BDNF and hippocampal volume in patients with Mild Cognitive Impairment (MCI) and dementia due to Alzheimer's disease, and healthy elderly participants. Method: Ten healthy elderly subjects, 10 MCI and 13 patients with dementia due to Alzheimer's Disease (NIA-AA criteria) were selected for the study. All participants were assessed cognitively. The ELISA method was used for BDNF analysis, and the analysis of hippocampal volumetric images were acquired with 1.5T magnetic resonance equipment and volumes obtained with NeuroQuant® program. Results: Healthy elderly had higher BDNF serum levels than MCI and dementia due to AD patients. The group of dementia patients had lower total hippocampal volume than MCI and healthy elderly participants. No significant correlation between serum BDNF and hippocampal volume was observed. Conclusion: Taking our results together (lower BDNF levels in MCI and dementia due to AD and smaller hippocampal volume in dementia due to AD) we can hypothesize that the decrease of BDNF may start before the establishment of neuronal injury expressed by the hippocampal reduction.

Les crises fébriles représentent l'évènement épileptique le plus fréquent dans l'espèce humaine et touchent 5 % de la population. Bien que la bénignité de leur pronostic ait été établie par de nombreuses études prospectives, une infime proportion de ces enfants va développer un syndrome d'épilepsie mésio-temporale avec sclérose de l'hippocampe. L'hypothèse de ce travail est que la crise fébrile serait nécessaire mais non suffisante au développement de ce type d'épilepsie, un second élément au potentiel épileptogène serait ainsi indispensable. Notre travail a montré que les crises hyperthermiques chez la souris constituent une bonne approche pour modéliser les crises fébriles de l'enfant. Nous avons ainsi montré que les conséquences des crises hyperthermiques étaient différentes selon la séquence de survenue par rapport au second évènement épileptogène. (i) Lorsque la crise hyperthermique précède l'injection de kaïnate dans l'hippocampe, elle accélère la phase d'épileptogenèse et majore la dispersion des cellules granulaires du gyrus denté, sans modifier la perte cellulaire des neurones pyramidaux de la corne d'Ammon. Elle entraine également une modification du pattern des décharges rythmiques hippocampiques lors de la phase chronique, sans modifier la fréquence ni la durée de ces décharges. (ii) Lorsque la crise hyperthermique succède à la présence d'une dysplasie de la partie CA3 de la corne d'Ammon d'origine génétique, elle semble diminuer le risque de crise chez les animaux KO pour le gène de la double cortine. Pourtant, l'augmentation de la fréquence d'une néo-expression du NPY par les cellules granulaires, chez les animaux Hz pour cette mutation, suggère que les crises hyperthermiques favoriseraient la route vers une épilepsie, tout en activant la mise en place de mécanismes protecteurs contre la survenue des crises. En conclusion, les crises hyperthermiques faciliteraient la route vers l'épilepsie, mais n'auraient pas d'effet facilitateur sur la route vers la crise. / Whereas febrile seizures are the most common seizure type in children and are reported in the history of mesial temporal lobe epilepsy, their role in its etiology remains controversial. They have been suggested to modify the functional organization of the hippocampus but to require another insult to induce epilepsy. To test this hypothesis, we developed a model of hyperthermic seizures in mice and examined their long-term consequences on a second insult induced either by (i) intra-hippocampal kaïnic acid injection in adult animals or by (ii) hippocampal dysplasia developed by double-cortin knock-out mice. (i) While adults, mice that were subjected to hyperthermic seizures developed epileptogenesis more rapidly than sham mice. The occurrence and duration of hippocampal paroxysmal discharges were not modified by hyperthermic seizures, as was their mean time-frequency. In this model, hyperthermic seizures increased the granular cells dispersion, but have no influence on the massif pyramidal cell loss. (ii) In preexisting hippocampal dysplasia, the occurrence of hyperthermic seizures did not increase the proportion of seizures in double-cortin knock-out mice after hyperthermic seizures, and suggest that hyperthermic seizures rather might decrease recurrent seizures via the neo-expression of NPY. In conclusion, hyperthermic seizures in immature mice might facilitate the route to epilepsy, but did not exacerbate the route to seizures.

Introdução: Perda de memória é um dos sintomas mais comuns em pacientes nos estágios iniciais da doença de Alzheimer; esses déficits são um reflexo do envolvimento da formação do hipocampo. O BDNF tem sido relacionado com a plasticidade do hipocampo. Neste sentido, as combinações de biomarcadores, como, por exemplo, a volumetria do hipocampo, pode apresentar um maior valor preditivo para diferenciar doença de Alzheimer do envelhecimento normal em pacientes com comprometimento cognitivo leve. Objetivo: A presente tese de doutorado teve como objetivo avaliar os níveis séricos do BDNF e o volume do hipocampo em pacientes com demência devido à doença de Alzheimer, Comprometimento Cognitivo Leve (CCL) e idosos saudáveis. Métodos: Para realização do estudo foram selecionados 10 idosos saudáveis, 10 CCL e 13 pacientes com demência devido à doença de Alzheimer pelos critérios NIA-AA. Todos participantes foram submetidos a uma avaliação cognitiva. Para as análises do BDNF, foi utilizado método de ELISA e para as análises de volumetria do hipocampo as imagens foram obtidas por meio de equipamento de ressonância de 1.5T e os volumes obtidos por meio do programa NeuroQuant®. Resultados: Idosos saudáveis apresentaram níveis séricos mais elevados de BDNF do que os CCL e pacientes com demência. O grupo de pacientes com demência apresentou menor volume total do hipocampo do que os idosos saudáveis e os CCL. Não houve correlação significativa do BDNF sérico com volume do hipocampo. Conclusão: Considerando nossos resultados em conjunto (baixos níveis de BDNF nos grupos CCL e demência devido à DA e menor volume do hipocampo na demência devido à AD), podemos supor que a diminuição dos níveis de BDNF ocorre antes da lesão neuronal expressa pela redução do hipocampo. / Introduction: Memory impairment is the most common symptom in patients in the early stages of Alzheimer's disease; this deficit is a reflection of the involvement of the hippocampal formation. BDNF has been linked to the hippocampal plasticity. Combinations of biomarkers, such as the hippocampal volumetry may have higher predictive value for differentiating Alzheimer's disease from normal aging in patients with mild cognitive impairment. Objective: The objective of present thesis was to evaluate serum levels of BDNF and hippocampal volume in patients with Mild Cognitive Impairment (MCI) and dementia due to Alzheimer's disease, and healthy elderly participants. Method: Ten healthy elderly subjects, 10 MCI and 13 patients with dementia due to Alzheimer's Disease (NIA-AA criteria) were selected for the study. All participants were assessed cognitively. The ELISA method was used for BDNF analysis, and the analysis of hippocampal volumetric images were acquired with 1.5T magnetic resonance equipment and volumes obtained with NeuroQuant® program. Results: Healthy elderly had higher BDNF serum levels than MCI and dementia due to AD patients. The group of dementia patients had lower total hippocampal volume than MCI and healthy elderly participants. No significant correlation between serum BDNF and hippocampal volume was observed. Conclusion: Taking our results together (lower BDNF levels in MCI and dementia due to AD and smaller hippocampal volume in dementia due to AD) we can hypothesize that the decrease of BDNF may start before the establishment of neuronal injury expressed by the hippocampal reduction.