Diss. (sammanfattning) Stockholm : Karol. inst., 2004. / Härtill 4 uppsatser.

Recent research, that has been focused on recognition memory, has revealed that two processes contribute to recognition of previously encountered items: recollection and familiarity (Aggleton & Brown, 1999; Eichenbaum, 2006; Eichenbaum, Yonelinas, & Ranganath, 2007; Rugg & Yonelinas, 2003; Skinner & Fernandes, 2007; Squire, Stark, & Clark, 2004; Wixted, 2007a; Yonelinas, 2001a; Yonelinas, 2002). The findings of neural correlates of recollection and familiarity lead to the assumption that there are different brain regions activated in either process, but there are, to the best of my knowledge, no studies assessing how these brain regions are working together in a recollection or a familiarity network, respectively. Additionally, there are almost no studies to date, which directly searched for overlapping regions. Therefore, in study I of the current thesis, brain regions associated to both recognition processes are searched investigated. Additionally, a connectivity analysis will search for functional correlated brain activations that either build a recollection or a familiarity network. It is undoubtable that the Brain Derived Neurotrophic Factor (BDNF) is strongly involved in synaptic plasticity in the hippocampus (Bramham & Messaoudi, 2005) and there is evidence that a genetic variant of this neurotrophin (BDNF 66Met) is related to poorer memory performance (Egan, et al., 2003). Therefore, in study II of the current thesis, the effect of BDNF Val66Met on recollection and familiarity performance and related brain activations is investigated. Finally, one could summarize, that serotonin, like BDNF, is strongly involved in brain development and plasticity as well as in learning and memory processes (Vizi, 2008). More precisely, there is evidence for alterations in the structure of brain regions, which are known to be involved in emotional memory formation and retrieval, like amygdala and hippocampus (Frodl, et al., 2008; Munafo, Brown, & Hariri, 2008; Pezawas, et al., 2005). One study found an slight epistatic effect of BDNF and 5-HTTLPR on the grey matter volume of the amygdala (Pezawas, et al., 2008). Therefore, in study III, it is investigated if such an interaction effect could be substantiated for the amygdala and additionally revealed for the hippocampus. The results of the current thesis allow further comprehension of recollection, hence episodic memory, and point to a special role of the BDNF in temporal and prefrontal brain regions. Additionally, the finding of an epistatic effect between BDNF and serotonin transporter function point to the need of analyzing interactions between genes and also between genes and environmental factors which reveals more information than the study of main effects alone. In conclusion, analyzing behavioral and neural correlates of episodic memory reveal allowed insights in brain functions that may serve as guideline for future studies in clinical populations with memory deficits, including susceptibility factors such as good or bad environment, as well as promising gene variants that influence episodic memory.

La présente thèse est liée à l'étude des indices externes au réseau neuronal et comment ceux-ci impactent le développement du système nerveux central. Spécifiquement, notre objectif était d'explorer l'effet de la leptine, une hormone sécrétée par les adipocytes, sur la plasticité développementale GABAergique. Nous avons utilisé des tranches aigues d'hippocampe de rat nouveau-né pour montrer que la leptine induit une potentialisation de la fréquence de l'activité miniature GABAergique, nécessitant une augmentation postsynaptique de calcium et l'activation de voies de signalisation spécifiques. Nous avons confirmé cet effet sur des cultures de neurones hippocampiques, sur lesquelles nous avons commencé à développer une méthode pour mesurer le corrélat morphologique de la plasticité fonctionnelle des synapses GABAergiques en culture. Cette approche suggère que la plasticité GABAergique induite par la leptine pourrait survenir à densité constante de récepteurs GABAA membranaires. La leptine induit donc une potentialisation de l'activité GABAergique dans les neurones hippocampiques en développement. Enfin, nous avons trouvé que les neurones pyramidaux de CA3 reçoivent une activité miniature GABAergique réduite chez des souris ob/ob ne produisant pas de leptine, suggérant que la leptine contribue au développement de la circuiterie GABAergique in vivo. Dans l'ensemble, les études que nous présentons apportent un éclairage nouveau sur le développement d'aires cérébrales dites de « haut niveau », dont nous avons observé qu'elles intègrent des signaux dits de « bas niveau », c'est-à-dire en provenance de la périphérie afin de modeler leur développement. / The present dissertation tackles the larger question of how external cues impact the development of the central nervous system. Our specific aim was to explore the effect of leptin, an adipocyte-derived hormone, on GABAergic plasticity in the developing rodent hippocampus. We used acute hippocampal slices of newborn rats to show that leptin induces a long lasting potentiation of the frequency of miniature GABAergic activity. Using pharmacological tools we found that this event requires a postsynaptic increase in intracellular calcium as well as specific postsynaptic signaling pathways. To address the mechanistic action of leptin we confirmed the leptin-induced plasticity on hippocampal cultures and began to develop a method to measure the morphological correlate of GABAergic synapses in culture. Applying this method suggested that the leptin-induced GABAergic plasticity might occur with a constant density of postsynaptic GABAA receptor puncta. Taken together, these data show that leptin induces a potentiation of GABAergic activity in developing hippocampal neurons, perhaps by recruiting clusters of GABAA receptors expressed at the membrane to form newly functional GABAergic synapses. In addition we found that CA3 pyramidal neurons of leptin-deficient ob/ob mice exhibit lower miniature GABAergic activity compared to wild type littermates, which suggests that leptin contributes to the development of the hippocampal GABAergic circuitry in vivo. Overall, these studies shed a new light on the development of admittedly "higher-level" cerebral regions which were found here to integrate "lower-level", peripheral signals to shape their development.

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

A prevalência de Doença Mental Grave (do inglês Severe Mental Illness, SMI) atinge 5,4% em um ano segundo os estudos Baltimore Epidemiologic Catchment Area e National Comorbidity Survey. O conceito de SMI surgiu na década de 1970 para o planejamento dos serviços de saúde e apresentou importância crescente a partir do movimento de desinstitucionalização psiquiátrica. Uma das definições para SMI deriva do NIMH (National Institute of Mental Health) em 1987, e utiliza como critérios a presença de prejuízo funcional, decorrente de déficits em aspectos básicos do dia-a-dia, bem como a duração da doença. Casos agudos de SMI podem necessitar tratamento em Unidade de Internação Psiquiátrica em Hospital Geral (UIPHG). No entanto, há poucos estudos disponíveis no Brasil avaliando esta modalidade de tratamento e os desfechos destes pacientes. Evidências também apontam que os pacientes com transtornos psiquiátricos apresentam níveis reduzidos de Fator Neurotrófico Derivado do Cérebro (Brain-Derived Neurotrophic Factor, BDNF). O BDNF age no sistema nervoso central (SNC) promovendo crescimento e diferenciação de neurônios. Dentro deste contexto, a presente tese apresenta como objetivo principal a avaliação naturalística de desfechos clínicos e funcionais, associados à avaliação dos níveis séricos de BDNF, em pacientes com SMI. Os pacientes que foram encaminhados para tratamento na Unidade de Internação Psiquiátrica do Hospital de Clínicas de Porto Alegre foram incluídos se apresentassem os critérios de SMI: Avaliação Global de Funcionamento (Global Assessment of Functioning, GAF) menor ou igual a 50 e tempo de tratamento maior ou igual a dois anos. As avaliações ocorreram em dois momentos (admissão e alta). Compreenderam avaliação sociodemográfica, clínica e coleta de sangue (com dosagem de BDNF sérico). Foram realizadas avaliação diagnóstica pelo Mini-International Neuropsychiatric Interview (MINI) e aplicação das escalas Brief Psychiatric Rating Scale (BPRS), Clinical Global Impression scale (CGI-S), GAF e World Health Organization Quality of Life Instrument—Short Version (WHOQOL-Bref). Ainda, foram aplicadas escalas específicas nos diagnósticos principais (i.e., depressão maior, depressão bipolar, episódio maníaco, esquizofrenia): Hamilton Depression Rating Scale (HAM-D); Young Mania Rating Scale (YMRS). O primeiro artigo desta tese descreve os desfechos clínicos, funcionais e também de qualidade de vida durante a internação psiquiátrica. Observou-se melhora significativa nos parâmetros avaliados nos pacientes com SMI como um todo. Os pacientes com episódio maníaco apresentaram maior chance (em relação aos com episódio depressivo) de atingir remissão pela CGI (OR: 4.03; 95% CI: 1.14-14.30; p=0.03). A duração média da hospitalização (LOS) foi 28,95 (± 19,86) dias. No segundo artigo, observou-se redução dos níveis séricos de BDNF nos pacientes com SMI em relação aos controles saudáveis, independentemente do diagnóstico. Houve aumento significativo no BDNF entre a admissão e a alta. Os resultados apresentados replicam dados previamente publicados a partir de amostra única de pacientes com SMI, sua característica diferencial. Estes resultados reforçam que a internação em UIPHG, uma intervenção relativamente breve, demonstra desfechos positivos e é alternativa bem estabelecida no tratamento da SMI. Além disso, a redução inespecífica do BDNF sérico seguida de um pequeno aumento associado ao tratamento reforçam a possibilidade do BDNF como marcador transdiagnóstico de transtorno mental. / The estimated prevalence of Severe Mental Illness (SMI) according to Baltimore Epidemiologic Catchment Area and National Comorbidity Survey studies is 5.4% in one year. One suggested definition of Severe Mental Illness (SMI) derives from the 1987 National Institute of Mental Health (NIMH) definition and is based on two criteria: 1. duration, characterized as involving “prolonged illness”, and 2. disability, which includes dangerous or disturbing social behavior, and mild impairment in achieving basic needs. These acute psychiatric conditions may require psychiatric inpatient treatment located in acute wards in General Hospitals. However, little data is currently available evaluating the characteristics and the outcomes during an acute inpatient stay in Brazil. Evidence also suggests that Brain-derived neurotrophic factor (BDNF) levels are significantly decreased in neuropsychiatric disorders. BDNF is found throughout the brain and is involved in neurogenesis and neuroplasticity. So, the main objectives of this work are to evaluate SMI patients’ outcomes during treatment in a psychiatric unit in a general hospital by symptomatology, functionality, quality of life and by the evaluation of BDNF serum levels. After the admission to a psychiatric unit in a general hospital in Brazil, patients were included and if they had two of the SMI criteria: Global Assessment of Functioning (GAF) ≤ 50 and duration of services contact ≥ 2 years. Patients were assessed in admission and upon discharge with Mini-International Neuropsychiatric Interview (MINI), Brief Psychiatric Rating Scale (BPRS), Clinical Global Impression Scale (CGI), GAF, World Health Organization’s QOL Instrument—Short Version (WHOQOL-Bref) and diagnostic specific scales (Hamilton Depression Rating Scale, HAM-D; Young Mania Rating Scale, YMRS; and Hamilton Anxiety Rating Scale, HAM-A). Blood samples were also obtained. The first manuscript showed that SMI patients had marked and significant improvements in symptomatic and functional measures during psychiatric hospitalization. Patients with manic episode had higher chance of CGI remission (OR: 4.03; 95% CI: 1.14-14.30; p=0.03) when compared with patients with depressive episode. Mean LOS was 28.95 (± 19.86) days. The second manuscript showed that BDNF serum levels were equally reduced among different SMI diagnoses. Also, the observed improvements in SMI patients were associated with a significant, but small increase in mean serum BDNF levels. Therefore, the results replicate evidence from previous findings in single samples, suggesting that SMI patients can have marked acute improvements during a a relatively short intervention (approximately 1 month) represented by the psychiatric hospitalization in a general tertiary hospital. Also, the similar reduction observed in BDNF levels among SMI patients with different diagnoses and the significant increase but non-restoration indicate that BDNF serum levels could be considered a marker for the presence of an unspecific psychiatric disorder and possibly a transdiagnostic and unspecific marker of disease activity.

As leucemias correspondem a 30% dos tumores pediátricos, e constituem as neoplasias mais frequentes em indivíduos com menos de 15 anos. Apesar da elevada taxa de cura, frequentemente a ela está associada resistência à quimioterapia e efeitos colaterais tardios. Por isso, novas estratégias de tratamento, diagnóstico e prognóstico são necessárias. O fator neurotrófico derivado do cérebro (BDNF) e seus receptores de quinase relacionados à tropomiosina (tropomyosin related kinase, ou Trk) estão envolvidos com muitos processos na medula óssea (MO). Entretanto, o papel do BDNF em leucemias agudas (LA) pediátricas ainda não é bem conhecido. O objetivo desse estudo foi analisar os níveis de BDNF em amostras de MO ou sangue periférico (SP) de crianças com LA, e iniciar a caracterização dos efeitos de agonistas e antagonistas de neurotrofinas sobre culturas primárias de leucemias linfóides agudas em diferentes momentos terapêuticos Foram coletadas amostras de MO ou SP de crianças e adolescentes com leucemia linfóide aguda (LLA), crianças e adolescentes com leucemia mielóide aguda (LMA), e indivíduos saudáveis (IS) da mesma faixa etária. Para análise dos níveis séricos de BDNF utilizou-se kit de imuno-ensaio enzimático tipo sanduíche. Quando comparados aos IS os níveis de BDNF de pacientes com LA, ao diagnóstico, foram significativamente menores. Resultados similares foram observados nos pacientes durante indução, consolidação, diagnóstico e tratamento de recidiva. Da mesma forma, os níveis de BDNF foram inferiores em pacientes que receberam transfusão de plaquetas e, ao diagnóstico naqueles pacientes que foram a óbito. Para a caracterização dos efeitos de agonistas e antagonistas de neurotrofinas em cultura de células, amostras de pacientes ao momento do diagnóstico e no momento de indução do tratamento foram utilizadas. Os linfócitos foram extraídos e, após plaqueamento, as células foram tratadas com BDNF (Sigma, B3795), NGF (Sigma, SRP3015) e K252a (Sigma, 05288) por 72 horas. A viabilidade foi avaliada pelo método de exclusão por azul de Tripan. Devido às dificuldades no cultivo das células, esses dados ainda estão em análise. / Leukemias account for 30% of pediatric tumors and are the most frequent cancers in people under 15 years. Despite the high cure rate, often it is associated with resistance to chemotherapy and late side effects. Therefore, new strategies for treatment, diagnosis and prognosis are necessary. The brain-derived neurotrophic factor (BDNF) and their kinase receptor related tropomyosin (tropomyosin related kinase, and Trk) are involved in many processes in bone marrow (BM), however, the role of BDNF in acute leukemias (AL) pediatric it is not well known. The aim of this study was to analyze the BDNF levels in BM samples or peripheral blood (PB) of children with AL, and start the characterization of the effects of agonists and antagonists on neurotrophin primary cultures of acute lymphoblastic leukemias in different therapeutic moments. BM or PB samples were collected from children and adolescents with acute lymphoblastic leukemia (ALL), children and adolescents with acute myeloid leukemia (AML), and healthy individuals (HI) of the same age. For analysis of serum levels of BDNF was used sandwich enzyme immunoassay kit. When compared to HI, BDNF levels in patients with AL at diagnosis were significantly lower. Similar results were observed in patients during induction, consolidation, diagnosis and treatment of relapse. Similarly, BDNF levels were lower in patients receiving platelet transfusion and at diagnosis in patients that died. To characterize the effects of agonists and antagonists for neurotrophin in cell culture, samples of patients at diagnosis and at the time of induction treatment were used. Lymphocytes were extracted and, after plating, cells were treated with BDNF (Sigma B3795), NGF (Sigma, SRP3015) and K252a (Sigma, 05288) for 72 hours. Viability was assessed by exclusion of trypan blue method. Due to difficulties in cell culture, these data are still under analysis.

Pang Petti. / "August 2004." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

Introdução: A cefaleia do tipo tensional crônica (CTTC) é caracterizada por dor de cabeça quase diária e sensibilização central. A acupuntura tem sido estudada no tratamento de diversos tipos de cefaleia, porém os resultados são controversos e apenas sugerem maior eficácia em relação ao placebo. A eletroacupuntura (EA) modula algumas das funções do sistema nervoso central (SNC), podendo modificar a neuroplasticidade. A plasticidade do SNC pode ser rastreada através dos níveis séricos do fator neurotrófico derivado do cérebro (BDNF), um mediador de neuroplasticidade. Objetivo: Este estudo testou a hipótese de que a analgesia pela EA na CTTC estaria relacionada à neuroplasticidade, avaliada através dos níveis séricos de BDNF. Métodos: Foram recrutadas mulheres, com idades entre 18-60 anos, portadoras de CTTC, para um ensaio clinico randomizado, cegado, controlado por placebo-sham. Foram aplicadas 10 sessões de EA, durante 30 minutos (2- 10 Hz, com intensidade conforme a tolerância) na cervical e áreas autonômicas, duas vezes por semana, que foram comparadas com placebosham. Os períodos de tratamento foram separados por duas semanas de intervalo. Avaliou-se dor (através de escala análoga visual (VAS) de 10 cm) e níveis séricos de BDNF como desfechos primários. Resultados: Trinta e quatro pacientes foram randomizadas e vinte e nove completaram o protocolo. Os escores da VAS foram menores durante o tratamento com EA, do que no tratamento com placebo-sham. (2.38±1.77, 3.02±2.49 respectivamente, P=0.005). Os escores de dor variaram conforme a sequência de intervenção, demonstrando efeito de carreamento (P<0.05). Utilizando regressão múltipla, os níveis séricos de BDNF foram ajustados para a escala de depressão de Hamilton e VAS (r-squared= 0.07, standard β coefficients= -0.2, -0.14, respectivamente). Ao final do período da primeira intervenção os valores de BDNF ajustados, foram maiores no grupo EA, (29.31±3.24, 27.53±2.94 ng/mL) a magnitude de efeito mensurada pela diferença na media padronizada expressou um efeito moderado (Cohen´s d= 0.55). Conclusão: A analgesia produzida pela EA pode estar relacionada à neuroplasticidade, avaliada através do BDNF ajustado para dor e depressão. A modulação pela EA na dor e BDNF depende da condição do SNC, uma vez que está relacionada à depressão e depende do momento da aplicação da intervenção. / Background: Chronic tension-type headache (CTTH) is characterized by almost daily headaches and central sensitization. Electroacupunture (EA) is effective for this condition and modules some central nervous system (CNS) functions. CNS plasticity could be tracked in serum using the brain derived neurotrophic factor (BDNF), a neuroplasticity mediator. Objective: We tested the hypothesis that EA analgesia in CTTH would be related to neuroplasticity indexed by the BDNF. Patients and methods: We enrolled females aging 18-60 with CTTH in a randomized, blinded, placebo-controlled crossover trial, comparing ten EA sessions applied during 30 minutes (2-10 Hz, intensity by tolerance) in cervical and autonomic areas twice per week, vs. placebo-sham (PS). Treatment periods were separated by two washout weeks. Pain on the 10 cm visual analog scale (VAS) and serum BDNF were assessed as primary outcomes. Results: Thirty-four subjects underwent randomization, twenty-nine completed the protocol. VAS during EA period was lower than during PS (2.38±1.77, 3.02±2.49 respectively, P=0.005). VAS differed according to intervention sequence demonstrating carry-over effect (P<0.05). Using multiple regression serum BDNF was adjusted for the Hamilton depression rating scale (HDRS) and VAS (r-squared=0.07, standard β coefficients=-0.2, -0.14, respectively; omnibus-test P<0.001). At the end of the first intervention period the adjusted BDNF was higher in the EA cohort (29.31±3.24, 27.53±2.94 ng/mL, Cohen´s d= 0.55). Conclusion: EA analgesia may relate to neuroplasticity indexed by the adjusted BDNF. EA modulation on pain and BDNF depends on the situation of the CNS, as is related to depression and depends on the timing of the intervention.

Major depressive disorder (MDD) affects 300 million people worldwide and is a major contributor to the global burden of disease. The aetiology of depression, emerging through a gene x environment interaction, is still incompletely understood which prevents tailoring of treatment approaches. In addition to MDD core symptoms, such as anhedonia (a diminished anticipation or experience of pleasure), depressed patients suffer from a plethora of manifestations including cognitive impairments, which occur primarily in the domains of executive function, attention and memory. Patients remitted from affective symptoms of MDD often continue to display cognitive impairments. These cognitive deficits are the longest present residual symptom, predict treatment response and increase risk of relapse. Consequently, cognitive impairments need to be targeted more effectively by antidepressants for complete remission from MDD. Clinically relevant animal models are essential for developing, tailoring and testing such novel, pro-cognitive antidepressants. This PhD project aimed to establish a preclinical screening platform for the testing of pro-cognitive antidepressants, to improve understanding of MDD risk factors and consequent symptom development, and finally, to focus on clinical relevance of the applied techniques. The chronic mild stress (CMS) rodent model of depression was used, known for displaying the core symptom anhedonia, but also for a high construct, face and predictive validity. The environmental MDD risk factor 'stress' induces an anhedonic-like phenotype in a subgroup of exposed rats, whereas another subgroup of rats is resilient, as determined by the sucrose consumption test. The cognitive performance of different rat strains, including CMS anhedonic-like and resilient rats, was assessed employing the touchscreen operant platform, which was developed based on the Cambridge neuropsychological test automated battery (CANTAB) for assessing cognition in humans. Furthermore, a group of anhedonic-like rats was treated with the antidepressant vortioxetine, which acts as both a pro-cognitive and antidepressant treatment. Our results showed that stress exposure induced anhedonia in albino and pigmented rat strains, although stress did not affect cognitive performance of pigmented rats in a simple pairwise discrimination touchscreen task. Applying a more complex pairedassociates learning touchscreen task revealed impaired cognitive performance in the CMS anhedonic-like but not in the resilient phenotype. Furthermore, vortioxetine treatment reversed anhedonia in the CMS model and altered executive functions in treated rats. The expression of genes involved in the stress response, affective disorders and neuronal plasticity was altered in the prefrontal cortex and hippocampus owned to treatment and hedonic state. Thus, we have demonstrated that the CMS model exhibits both stress-induced cognitive alterations and depression-associated cognitive impairments in touchscreen tasks. Furthermore, touchscreen testing was sufficiently sensitive to detect alterations in cognitive performance due to pharmacological intervention. Overall, we established a potential platform for pro-cognitive antidepressant drug screening. Furthermore, brain derived neurotrophic factor (BDNF), involved in learning and memory, was examined in the context of depression. BDNF is reduced in MDD patients as well as in preclinical models in response to stress. Although this suggests that BDNF contributes to the aetiology of depression, studies including mice heterozygous for BDNF (BDNF+/-) have generated conflicting results. BDNF+/- rats may provide a more suitable model as (1) rats have a greater behavioural repertoire than mice, (2) classical behaviour tests are designed for rats, and (3) rats, like humans, produce peripheral BDNF. We found anhedonia and mild signs of anxiety in BDNF+/- rats, accompanied by prefrontal and hippocampal changes in expression of genes relevant in psychiatric disorders and underpinning learning. Thus, behavioural and molecular findings in BDNF+/- rats complement existing literature and suggest that rats are a more suitable model in BDNF research than mice. Overall, the project uncovered environmental and genetic manifestations of risk factors in translational models and established a novel tool for translational pro-cognitive antidepressant drug screening.

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