Thesis (Ph. D.)--University of Washington, 2007. / Vita. Includes bibliographical references (leaves 81-97).

Brain-machine interfaces (BMIs) hold promise for restoring motor functions in severely paralyzed individuals. Invasive BMIs are capable of recording signals from individual neurons and typically provide the highest signal-to-noise ratio. Despite many efforts in the scientific community, BMI technology is still not reliable enough for widespread clinical application. The most prominent challenges include biocompatibility, stability, longevity, and lack of good models for informed signal processing and BMI comparison. To address the problem of low signal quality of chronic probes, in the first part of the thesis one such design, the Neurotrophic Electrode, was modified by increasing its channel capacity to form a Neurotrophic Array (NA). Specifically, single wires were replaced with stereotrodes and the total number of recording wires was increased. This new array design was tested in a rhesus macaque performing a delayed saccade task. The NA recorded little single unit spiking activity, and its local field potentials (LFPs) correlated with presented visual stimuli and saccade locations better than did extracted spikes. The second part of the thesis compares the NA to the Utah Array (UA), the only other micro-array approved for chronic implantation in a human brain. The UA recorded significantly more spiking units, which had larger amplitudes than NA spikes. This was likely due to differences in the array geometry and construction. LFPs on the NA electrodes were more correlated with each other than those on the UA. These correlations negatively impacted the NA's information capacity when considering more than one recording site. The final part of this dissertation applies information theory to develop objective measures of BMI performance. Currently, decoder information transfer rate (ITR) is the most popular BMI information performance metric. However, it is limited by the selected decoding algorithm and does not represent the full task information embedded in the recorded neural signal. A review of existing methods to estimate ITR is presented, and these methods are interpreted within a BMI context. A novel Gaussian mixture Monte Carlo method is developed to produce good ITR estimates with a low number of trials and high number of dimensions, as is typical for BMI applications.

Introdução: Existem fortes evidências de um fator genético estar envolvido na etiologia do transtorno bipolar (TB), contudo a interação entre polimorfismos genéticos e alterações bioquímicas permanecem desconhecidas. O fator neurotrófico derivado do cérebro (BDNF) parece exercer um papel importante na patofisiologia do TB. Objetivos: O presente estudo tem por objetivo avaliar a associação do polimorfismo localizado no gene do fator neurotrófico derivado do cérebro (BDNF) e os níveis séricos desta substância em pacientes com transtorno bipolar. Material e Métodos: Foram selecionados 114 pacientes com TB tipo I de acordo com critério do DSMIV e 137 controles pareados por sexo, idade e anos de estudo para a análise do polimorfismo val66met do BDNF e do BDNF sérico. Suas associações foram medidas através da análise de variância (ANOVA).Resultados: Não houve diferenças significativas na freqüência dos genótipos do polimorfismo val66met do BDNF entre pacientes e controles (p>0.05; teste Qui-quadrado). Não foi encontrada associação entre o polimorfismo do gene do BDNF e o diagnósticode transtorno bipolar(eutímicos) nos níveis séricos de BDNF (p=0.34; ANOVA Fatorial) Conclusão: O polimorfismo do BDNF val66met parece não interferir no nível sérico de BDNF em pacientes bipolares em tratamento e controles sem TB, sugerindo que a variante BDNFMet não diminui a secreção constitutiva; possivelmente este polimorfismo do BDNF exerça alguma influencia nos níveis séricos do BDNF durante os episódios agudos da doença. / Introduction: There is strong evidence demonstrating that genetic inheritance is associated with higher susceptibility to bipolar disorder (BD) but the interaction between gene polymorphisms and biochemical changes remains largely unknown. The brainderived neurotrophic factor (BDNF) may play a role in the pathophysiology of BD. Objectives: The aim of the present study was to evaluate the association between BDNF polymorphism val66met and its serum levels in bipolar patients. Methods: One hundred and seven Caucasian type-I bipolar patients were recruited from the Bipolar Disorders Program and underwent Structured Clinical Interview for DSMIV- Axis I for diagnosis. The subjects were matched by age, gender and education with137 controls without BD. The association between BDNF serum levels and polymorphism was analysed by ANOVA. Results: No significant differences were found in the frequency of the BDNF val66met genotype or allele distribution between patients and controls (p>0.05; Chi-square test). We have found no significant interaction between BDNF polymorphism anddiagnostic status (bipolar disorder and controls) on serum BDNF levels (p=0.34; Factorial ANOVA) Conclusion: BDNF val66met polymorphism does not affect serum BDNF levels in a sample of mostly euthymic BD subjects currently on medication. Considering that the BDNFMet variant decreases only the activity-dependent but not the constitutive BDNF secretion, it is conceivable that BDNF polymorphism may exert some influence on serum BDNF levels during acute mood episodes.

Introdução: Em humanos, sugere-se que um trauma precoce está relacionado com o desenvolvimento de transtornos de ansiedade na vida adulta. Essa relação poderia ser mediada pela resposta ao estresse, fator neurotrófico derivado do encéfalo (BDNF) e/ou óxido nítrico sintase neuronal (nNOS). O objetivo deste trabalho foi propor um modelo animal para o desenvolvimento de ansiedade, utilizando, como intervenção, um ambiente neonatal hostil que afeta o cuidado materno, além de verificar potenciais mecanismos relacionados ao desenvolvimento de ansiedade. Também objetivou-se investigar associações similares em humanos. Métodos: Ao segundo dia de vida, ninhadas de ratos Wistar e suas genitoras foram divididas em dois grupos: grupo intervenção, com redução do material disponível para a confecção do ninho, ou grupo controle. O comportamento materno foi observado do dia 1 ao dia 9 de vida. Após o desmame, o peso corporal e o consumo de ração padrão foram avaliados uma vez por semana. Na vida adulta, os ratos foram submetidos a testes comportamentais. Foram determinados os níveis plasmáticos de glicose e o perfil lipídico, além da quantidade de BDNF no plasma, hipocampo, amígdala e sustância cinzenta periaquedutal e de óxido nítrico no hipocampo. Um subgrupo de animais intactos foi submetido ao estresse por restrição para avaliação da curva de corticosterona. Em humanos, 129 adolescentes com sintomas ansiosos, avaliados pela escala Screen for Children and Anxiety Related Emotional Disorders (SCARED), responderam ao Parental Bonding Instrument (PBI), coletaram sangue para avaliação do BDNF e foram genotipados para o polimorfismo Val66Met do BDNF. Resultados: As genitoras do grupo intervenção apresentaram um maior contato de baixa qualidade com seus filhotes, comparadas às genitoras controles. O consumo alimentar de ração padrão foi menor no grupo intervenção. Não houve diferença entre os grupos no peso corporal, no consumo de alimento palatável, na hiperfagia de rebote, nem no teste do campo aberto. No teste do labirinto em cruz elevado, observou-se que a intervenção esteve associada a maior ansiedade, porém de forma diferenciada entre os sexos. Foram observados níveis maiores de BDNF plasmáticos no grupo intervenção e uma correlação positiva entre o contato de baixa qualidade e o BDNF periférico. Não houve diferença entre os grupos na quantidade de BDNF no hipocampo, amígdala e sustância cinzenta periaquedutal e, também, nos níveis de óxido nítrico no hipocampo. Machos do grupo intervenção levaram mais tempo para atingir o pico de corticosterona em resposta ao estresse. No estudo clínico, observaram-se correlações negativas entre o cuidado materno e sintomas ansiosos, assim como uma correlação positiva entre a superproteção materna e os níveis periféricos de BDNF apenas nos indivíduos portadores do alelo Met. Conclusão: O modelo animal proposto mostrou que o estresse precoce, capaz de alterar a relação mãe-filhote, tem impacto persistente sobre o comportamento do tipo ansioso e os níveis periféricos de BDNF. Estes achados são similares às associações descritas em humanos. A abordagem translacional da questão evidenciou que os efeitos do trauma no início da vida podem ser mediados pelo cuidado materno, sendo o aumento do BDNF periférico um marcador em potencial para esses indivíduos. / Introduction: In humans, there is the suggestion that an adverse early life environment is related to the development of anxiety disorders in adulthood. This association could potentially be mediated by stress responses, brain-derived neurotrophic factor (BDNF) and by neuronal nitric oxide synthase (nNOS). This study aimed at proposing an animal model for the development of adult anxiety-like behavior, using as intervention an adverse early life environment affecting matenal care, and verifies potencial mechanisms related to the development of anxiety-like behavior. Another aim was investigate similar associations in humans. Methodology: By the second day of life, litters of Wistar rats and their dams where divided in two groups: intervention, with limited access to nesting material, or control. Maternal behavior was observed from day 1 to day 9 of life. After weaning, animals’ weight and standard chow consumption were measured once a week. Starting on day 60 of life, rats were submitted to behavioral testing. Glucose and lipid profile were assessed. Plasma, hippocampus, amygdala and periaqueductal gray BDNF contents and hippocampus nitric oxide were also measured. A subgroup of naive animals was submitted to restraint stress for determination of corticosterone curve. In humans, 129 adolescents, screened for anxiety using the Screen for Children and Anxiety Related Emotional Disorders (SCARED) scale, responded to the Parental Bonding Instrument (PBI), collected blood for BDNF measurements and were genotyped for BDNF Val66Met polymorphism. Results: Intervention dams showed increased contact of low quality with their pups when compared to control dams. The intervention group consumed less standard chow than the control group. No differences in body weight gain, acute palatable food consumption, rebound hyperphagia and open field test were observed between groups. On plus maze test, the intervention was associated with higher anxiety-like behavior, however differently between the sexes. Higher plasma BDNF levels were found in the intervention group and low quality maternal care (pure contact) was positively correlated with adult peripheral BDNF. There were no differences in hippocampus, amygdala and periaqueductal gray BDNF contents, as hippocampus nitric oxide contents. Males of the intervention group took longer to reach the corticosterone peak. In humans, negative correlations between maternal care and anxiety symptoms were observed, as well as a positive correlation between overprotection and serum BDNF levels only among the Met carriers. Conclusion: The animal model proposed showed that an early life stress, able to alter the relationship between dam and pup, have a persistent impact on anxiety-like behavior and peripheral BDNF levels. These findings were similar to the associations described in humans. The translational approach to the question evidenced that the effects of early trauma may be mediated through maternal care, being the increased peripheral BDNF a potential relevant marker for these individuals.

Introdução: Em humanos, sugere-se que um trauma precoce está relacionado com o desenvolvimento de transtornos de ansiedade na vida adulta. Essa relação poderia ser mediada pela resposta ao estresse, fator neurotrófico derivado do encéfalo (BDNF) e/ou óxido nítrico sintase neuronal (nNOS). O objetivo deste trabalho foi propor um modelo animal para o desenvolvimento de ansiedade, utilizando, como intervenção, um ambiente neonatal hostil que afeta o cuidado materno, além de verificar potenciais mecanismos relacionados ao desenvolvimento de ansiedade. Também objetivou-se investigar associações similares em humanos. Métodos: Ao segundo dia de vida, ninhadas de ratos Wistar e suas genitoras foram divididas em dois grupos: grupo intervenção, com redução do material disponível para a confecção do ninho, ou grupo controle. O comportamento materno foi observado do dia 1 ao dia 9 de vida. Após o desmame, o peso corporal e o consumo de ração padrão foram avaliados uma vez por semana. Na vida adulta, os ratos foram submetidos a testes comportamentais. Foram determinados os níveis plasmáticos de glicose e o perfil lipídico, além da quantidade de BDNF no plasma, hipocampo, amígdala e sustância cinzenta periaquedutal e de óxido nítrico no hipocampo. Um subgrupo de animais intactos foi submetido ao estresse por restrição para avaliação da curva de corticosterona. Em humanos, 129 adolescentes com sintomas ansiosos, avaliados pela escala Screen for Children and Anxiety Related Emotional Disorders (SCARED), responderam ao Parental Bonding Instrument (PBI), coletaram sangue para avaliação do BDNF e foram genotipados para o polimorfismo Val66Met do BDNF. Resultados: As genitoras do grupo intervenção apresentaram um maior contato de baixa qualidade com seus filhotes, comparadas às genitoras controles. O consumo alimentar de ração padrão foi menor no grupo intervenção. Não houve diferença entre os grupos no peso corporal, no consumo de alimento palatável, na hiperfagia de rebote, nem no teste do campo aberto. No teste do labirinto em cruz elevado, observou-se que a intervenção esteve associada a maior ansiedade, porém de forma diferenciada entre os sexos. Foram observados níveis maiores de BDNF plasmáticos no grupo intervenção e uma correlação positiva entre o contato de baixa qualidade e o BDNF periférico. Não houve diferença entre os grupos na quantidade de BDNF no hipocampo, amígdala e sustância cinzenta periaquedutal e, também, nos níveis de óxido nítrico no hipocampo. Machos do grupo intervenção levaram mais tempo para atingir o pico de corticosterona em resposta ao estresse. No estudo clínico, observaram-se correlações negativas entre o cuidado materno e sintomas ansiosos, assim como uma correlação positiva entre a superproteção materna e os níveis periféricos de BDNF apenas nos indivíduos portadores do alelo Met. Conclusão: O modelo animal proposto mostrou que o estresse precoce, capaz de alterar a relação mãe-filhote, tem impacto persistente sobre o comportamento do tipo ansioso e os níveis periféricos de BDNF. Estes achados são similares às associações descritas em humanos. A abordagem translacional da questão evidenciou que os efeitos do trauma no início da vida podem ser mediados pelo cuidado materno, sendo o aumento do BDNF periférico um marcador em potencial para esses indivíduos. / Introduction: In humans, there is the suggestion that an adverse early life environment is related to the development of anxiety disorders in adulthood. This association could potentially be mediated by stress responses, brain-derived neurotrophic factor (BDNF) and by neuronal nitric oxide synthase (nNOS). This study aimed at proposing an animal model for the development of adult anxiety-like behavior, using as intervention an adverse early life environment affecting matenal care, and verifies potencial mechanisms related to the development of anxiety-like behavior. Another aim was investigate similar associations in humans. Methodology: By the second day of life, litters of Wistar rats and their dams where divided in two groups: intervention, with limited access to nesting material, or control. Maternal behavior was observed from day 1 to day 9 of life. After weaning, animals’ weight and standard chow consumption were measured once a week. Starting on day 60 of life, rats were submitted to behavioral testing. Glucose and lipid profile were assessed. Plasma, hippocampus, amygdala and periaqueductal gray BDNF contents and hippocampus nitric oxide were also measured. A subgroup of naive animals was submitted to restraint stress for determination of corticosterone curve. In humans, 129 adolescents, screened for anxiety using the Screen for Children and Anxiety Related Emotional Disorders (SCARED) scale, responded to the Parental Bonding Instrument (PBI), collected blood for BDNF measurements and were genotyped for BDNF Val66Met polymorphism. Results: Intervention dams showed increased contact of low quality with their pups when compared to control dams. The intervention group consumed less standard chow than the control group. No differences in body weight gain, acute palatable food consumption, rebound hyperphagia and open field test were observed between groups. On plus maze test, the intervention was associated with higher anxiety-like behavior, however differently between the sexes. Higher plasma BDNF levels were found in the intervention group and low quality maternal care (pure contact) was positively correlated with adult peripheral BDNF. There were no differences in hippocampus, amygdala and periaqueductal gray BDNF contents, as hippocampus nitric oxide contents. Males of the intervention group took longer to reach the corticosterone peak. In humans, negative correlations between maternal care and anxiety symptoms were observed, as well as a positive correlation between overprotection and serum BDNF levels only among the Met carriers. Conclusion: The animal model proposed showed that an early life stress, able to alter the relationship between dam and pup, have a persistent impact on anxiety-like behavior and peripheral BDNF levels. These findings were similar to the associations described in humans. The translational approach to the question evidenced that the effects of early trauma may be mediated through maternal care, being the increased peripheral BDNF a potential relevant marker for these individuals.

abstract: Chronic stress results in functional and structural changes to the hippocampus. Decades of research has led to insights into the mechanisms underlying the chronic stress-induced deficits in hippocampal-mediated cognition and reduction of dendritic complexity of hippocampal neurons. Recently, a considerable focus of chronic stress research has investigated the mechanisms behind the improvements in hippocampal mediated cognition when chronic stress ends and a post-stress rest period is given. Consequently, the goal of this dissertation is to uncover the mechanisms that allow for spatial ability to improve in the aftermath of chronic stress. In chapter 2, the protein brain derived neurotrophic factor (BDNF) was investigated as a mechanism that allows for spatial ability to show improvements following the end of chronic stress. It was found that decreasing the expression of BDNF in the hippocampus prevented spatial memory improvements following a post-stress rest period. Chapter 3 was performed to determine whether hippocampal CA3 apical dendritic complexity requires BDNF to show improvements following a post-stress rest period, and whether a receptor for BDNF, TrkB, mediates the improvements of spatial ability and dendritic complexity in a temporal manner, i.e. during the rest period only. These experiments showed that decreased hippocampal BDNF expression prevented improvements in dendritic complexity, and administration of a TrkB antagonist during the rest period also prevented the improvements in spatial ability and dendritic complexity. In chapter 4, the role of the GABAergic system on spatial ability following chronic stress and a post-stress rest period was investigated. Following chronic stress, it was found that male rats showed impairments on the acquisition phase of the RAWM and this correlated with limbic glutamic acid decarboxylase, a marker for GABA. In chapter 5, a transgenic mouse that expresses a permanent marker on all GABAergic interneurons was used to assess the effects of chronic stress and a post-stress rest period on hippocampal GABAergic neurons. While no changes were found on the total number of GABAergic interneurons, specific subtypes of GABAergic interneurons were affected by stressor manipulations. Collectively, these studies reveal some mechanisms behind the plasticity seen in the hippocampus in response to a post-stress rest period. / Dissertation/Thesis / Doctoral Dissertation Psychology 2018

Introdução: Existem fortes evidências de um fator genético estar envolvido na etiologia do transtorno bipolar (TB), contudo a interação entre polimorfismos genéticos e alterações bioquímicas permanecem desconhecidas. O fator neurotrófico derivado do cérebro (BDNF) parece exercer um papel importante na patofisiologia do TB. Objetivos: O presente estudo tem por objetivo avaliar a associação do polimorfismo localizado no gene do fator neurotrófico derivado do cérebro (BDNF) e os níveis séricos desta substância em pacientes com transtorno bipolar. Material e Métodos: Foram selecionados 114 pacientes com TB tipo I de acordo com critério do DSMIV e 137 controles pareados por sexo, idade e anos de estudo para a análise do polimorfismo val66met do BDNF e do BDNF sérico. Suas associações foram medidas através da análise de variância (ANOVA).Resultados: Não houve diferenças significativas na freqüência dos genótipos do polimorfismo val66met do BDNF entre pacientes e controles (p>0.05; teste Qui-quadrado). Não foi encontrada associação entre o polimorfismo do gene do BDNF e o diagnósticode transtorno bipolar(eutímicos) nos níveis séricos de BDNF (p=0.34; ANOVA Fatorial) Conclusão: O polimorfismo do BDNF val66met parece não interferir no nível sérico de BDNF em pacientes bipolares em tratamento e controles sem TB, sugerindo que a variante BDNFMet não diminui a secreção constitutiva; possivelmente este polimorfismo do BDNF exerça alguma influencia nos níveis séricos do BDNF durante os episódios agudos da doença. / Introduction: There is strong evidence demonstrating that genetic inheritance is associated with higher susceptibility to bipolar disorder (BD) but the interaction between gene polymorphisms and biochemical changes remains largely unknown. The brainderived neurotrophic factor (BDNF) may play a role in the pathophysiology of BD. Objectives: The aim of the present study was to evaluate the association between BDNF polymorphism val66met and its serum levels in bipolar patients. Methods: One hundred and seven Caucasian type-I bipolar patients were recruited from the Bipolar Disorders Program and underwent Structured Clinical Interview for DSMIV- Axis I for diagnosis. The subjects were matched by age, gender and education with137 controls without BD. The association between BDNF serum levels and polymorphism was analysed by ANOVA. Results: No significant differences were found in the frequency of the BDNF val66met genotype or allele distribution between patients and controls (p>0.05; Chi-square test). We have found no significant interaction between BDNF polymorphism anddiagnostic status (bipolar disorder and controls) on serum BDNF levels (p=0.34; Factorial ANOVA) Conclusion: BDNF val66met polymorphism does not affect serum BDNF levels in a sample of mostly euthymic BD subjects currently on medication. Considering that the BDNFMet variant decreases only the activity-dependent but not the constitutive BDNF secretion, it is conceivable that BDNF polymorphism may exert some influence on serum BDNF levels during acute mood episodes.

abstract: Chronic restraint stress impairs hippocampal-mediated spatial learning and memory, which improves following a post-stress recovery period. Here, we investigated whether brain derived neurotrophic factor (BDNF), a protein important for hippocampal function, would alter the recovery from chronic stress-induced spatial memory deficits. Adult male Sprague-Dawley rats were infused into the hippocampus with adeno- associated viral vectors containing the coding sequence for short interfering (si)RNA directed against BDNF or a scrambled sequence (Scr), with both containing the coding information for green fluorescent protein to aid in anatomical localization. Rats were then chronically restrained (wire mesh, 6h/d/21d) and assessed for spatial learning and memory using a radial arm water maze (RAWM) either immediately after stressor cessation (Str-Imm) or following a 21-day post-stress recovery period (Str-Rec). All groups learned the RAWM task similarly, but differed on the memory retention trial. Rats in the Str-Imm group, regardless of viral vector contents, committed more errors in the spatial reference memory domain than did non-stressed controls. Importantly, the typical improvement in spatial memory following recovery from chronic stress was blocked with the siRNA against BDNF, as Str-Rec-siRNA performed worse on the RAWM compared to the non-stressed controls or Str-Rec-Scr. These effects were specific for the reference memory domain as repeated entry errors that reflect spatial working memory were unaffected by stress condition or viral vector contents. These results demonstrate that hippocampal BDNF is necessary for the recovery from stress-induced hippocampal dependent spatial memory deficits in the reference memory domain. / Dissertation/Thesis / M.A. Psychology 2013

Introdução: Em humanos, sugere-se que um trauma precoce está relacionado com o desenvolvimento de transtornos de ansiedade na vida adulta. Essa relação poderia ser mediada pela resposta ao estresse, fator neurotrófico derivado do encéfalo (BDNF) e/ou óxido nítrico sintase neuronal (nNOS). O objetivo deste trabalho foi propor um modelo animal para o desenvolvimento de ansiedade, utilizando, como intervenção, um ambiente neonatal hostil que afeta o cuidado materno, além de verificar potenciais mecanismos relacionados ao desenvolvimento de ansiedade. Também objetivou-se investigar associações similares em humanos. Métodos: Ao segundo dia de vida, ninhadas de ratos Wistar e suas genitoras foram divididas em dois grupos: grupo intervenção, com redução do material disponível para a confecção do ninho, ou grupo controle. O comportamento materno foi observado do dia 1 ao dia 9 de vida. Após o desmame, o peso corporal e o consumo de ração padrão foram avaliados uma vez por semana. Na vida adulta, os ratos foram submetidos a testes comportamentais. Foram determinados os níveis plasmáticos de glicose e o perfil lipídico, além da quantidade de BDNF no plasma, hipocampo, amígdala e sustância cinzenta periaquedutal e de óxido nítrico no hipocampo. Um subgrupo de animais intactos foi submetido ao estresse por restrição para avaliação da curva de corticosterona. Em humanos, 129 adolescentes com sintomas ansiosos, avaliados pela escala Screen for Children and Anxiety Related Emotional Disorders (SCARED), responderam ao Parental Bonding Instrument (PBI), coletaram sangue para avaliação do BDNF e foram genotipados para o polimorfismo Val66Met do BDNF. Resultados: As genitoras do grupo intervenção apresentaram um maior contato de baixa qualidade com seus filhotes, comparadas às genitoras controles. O consumo alimentar de ração padrão foi menor no grupo intervenção. Não houve diferença entre os grupos no peso corporal, no consumo de alimento palatável, na hiperfagia de rebote, nem no teste do campo aberto. No teste do labirinto em cruz elevado, observou-se que a intervenção esteve associada a maior ansiedade, porém de forma diferenciada entre os sexos. Foram observados níveis maiores de BDNF plasmáticos no grupo intervenção e uma correlação positiva entre o contato de baixa qualidade e o BDNF periférico. Não houve diferença entre os grupos na quantidade de BDNF no hipocampo, amígdala e sustância cinzenta periaquedutal e, também, nos níveis de óxido nítrico no hipocampo. Machos do grupo intervenção levaram mais tempo para atingir o pico de corticosterona em resposta ao estresse. No estudo clínico, observaram-se correlações negativas entre o cuidado materno e sintomas ansiosos, assim como uma correlação positiva entre a superproteção materna e os níveis periféricos de BDNF apenas nos indivíduos portadores do alelo Met. Conclusão: O modelo animal proposto mostrou que o estresse precoce, capaz de alterar a relação mãe-filhote, tem impacto persistente sobre o comportamento do tipo ansioso e os níveis periféricos de BDNF. Estes achados são similares às associações descritas em humanos. A abordagem translacional da questão evidenciou que os efeitos do trauma no início da vida podem ser mediados pelo cuidado materno, sendo o aumento do BDNF periférico um marcador em potencial para esses indivíduos. / Introduction: In humans, there is the suggestion that an adverse early life environment is related to the development of anxiety disorders in adulthood. This association could potentially be mediated by stress responses, brain-derived neurotrophic factor (BDNF) and by neuronal nitric oxide synthase (nNOS). This study aimed at proposing an animal model for the development of adult anxiety-like behavior, using as intervention an adverse early life environment affecting matenal care, and verifies potencial mechanisms related to the development of anxiety-like behavior. Another aim was investigate similar associations in humans. Methodology: By the second day of life, litters of Wistar rats and their dams where divided in two groups: intervention, with limited access to nesting material, or control. Maternal behavior was observed from day 1 to day 9 of life. After weaning, animals’ weight and standard chow consumption were measured once a week. Starting on day 60 of life, rats were submitted to behavioral testing. Glucose and lipid profile were assessed. Plasma, hippocampus, amygdala and periaqueductal gray BDNF contents and hippocampus nitric oxide were also measured. A subgroup of naive animals was submitted to restraint stress for determination of corticosterone curve. In humans, 129 adolescents, screened for anxiety using the Screen for Children and Anxiety Related Emotional Disorders (SCARED) scale, responded to the Parental Bonding Instrument (PBI), collected blood for BDNF measurements and were genotyped for BDNF Val66Met polymorphism. Results: Intervention dams showed increased contact of low quality with their pups when compared to control dams. The intervention group consumed less standard chow than the control group. No differences in body weight gain, acute palatable food consumption, rebound hyperphagia and open field test were observed between groups. On plus maze test, the intervention was associated with higher anxiety-like behavior, however differently between the sexes. Higher plasma BDNF levels were found in the intervention group and low quality maternal care (pure contact) was positively correlated with adult peripheral BDNF. There were no differences in hippocampus, amygdala and periaqueductal gray BDNF contents, as hippocampus nitric oxide contents. Males of the intervention group took longer to reach the corticosterone peak. In humans, negative correlations between maternal care and anxiety symptoms were observed, as well as a positive correlation between overprotection and serum BDNF levels only among the Met carriers. Conclusion: The animal model proposed showed that an early life stress, able to alter the relationship between dam and pup, have a persistent impact on anxiety-like behavior and peripheral BDNF levels. These findings were similar to the associations described in humans. The translational approach to the question evidenced that the effects of early trauma may be mediated through maternal care, being the increased peripheral BDNF a potential relevant marker for these individuals.

Introdução: Existem fortes evidências de um fator genético estar envolvido na etiologia do transtorno bipolar (TB), contudo a interação entre polimorfismos genéticos e alterações bioquímicas permanecem desconhecidas. O fator neurotrófico derivado do cérebro (BDNF) parece exercer um papel importante na patofisiologia do TB. Objetivos: O presente estudo tem por objetivo avaliar a associação do polimorfismo localizado no gene do fator neurotrófico derivado do cérebro (BDNF) e os níveis séricos desta substância em pacientes com transtorno bipolar. Material e Métodos: Foram selecionados 114 pacientes com TB tipo I de acordo com critério do DSMIV e 137 controles pareados por sexo, idade e anos de estudo para a análise do polimorfismo val66met do BDNF e do BDNF sérico. Suas associações foram medidas através da análise de variância (ANOVA).Resultados: Não houve diferenças significativas na freqüência dos genótipos do polimorfismo val66met do BDNF entre pacientes e controles (p>0.05; teste Qui-quadrado). Não foi encontrada associação entre o polimorfismo do gene do BDNF e o diagnósticode transtorno bipolar(eutímicos) nos níveis séricos de BDNF (p=0.34; ANOVA Fatorial) Conclusão: O polimorfismo do BDNF val66met parece não interferir no nível sérico de BDNF em pacientes bipolares em tratamento e controles sem TB, sugerindo que a variante BDNFMet não diminui a secreção constitutiva; possivelmente este polimorfismo do BDNF exerça alguma influencia nos níveis séricos do BDNF durante os episódios agudos da doença. / Introduction: There is strong evidence demonstrating that genetic inheritance is associated with higher susceptibility to bipolar disorder (BD) but the interaction between gene polymorphisms and biochemical changes remains largely unknown. The brainderived neurotrophic factor (BDNF) may play a role in the pathophysiology of BD. Objectives: The aim of the present study was to evaluate the association between BDNF polymorphism val66met and its serum levels in bipolar patients. Methods: One hundred and seven Caucasian type-I bipolar patients were recruited from the Bipolar Disorders Program and underwent Structured Clinical Interview for DSMIV- Axis I for diagnosis. The subjects were matched by age, gender and education with137 controls without BD. The association between BDNF serum levels and polymorphism was analysed by ANOVA. Results: No significant differences were found in the frequency of the BDNF val66met genotype or allele distribution between patients and controls (p>0.05; Chi-square test). We have found no significant interaction between BDNF polymorphism anddiagnostic status (bipolar disorder and controls) on serum BDNF levels (p=0.34; Factorial ANOVA) Conclusion: BDNF val66met polymorphism does not affect serum BDNF levels in a sample of mostly euthymic BD subjects currently on medication. Considering that the BDNFMet variant decreases only the activity-dependent but not the constitutive BDNF secretion, it is conceivable that BDNF polymorphism may exert some influence on serum BDNF levels during acute mood episodes.