Participação de a-adrenoceptores do núcleo mediano da rafe no controle da resposta ingestiva em ratos saciados

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Biológicas, Programa de Pós-Graduação em Neurociências, Florianópolis, 2014.O presente estudo avaliou a participação de a-adrenoceptores do núcleo mediano da rafe (NMR) de ratos saciados, nas variáveis de ingestão de alimentos e água e comportamentos não ingestivos. Os animais controle foram tratados com salina (SAL) ou adrenalina (ADR), injetados no NMR sete minutos após a injeção do veículo utilizado para solubilizar os antagonistas, propilenoglicol (PLG) ou SAL. Os animais dos grupos experimentais foram tratados com um antagonista de a-adrenoceptores, prazosina (a1, 20 ou 40nmol) ou ioimbina (a2, 20 ou 40nmol) ou fentolamina (a não seletivo, 20 ou 40nmol), seguido, sete minutos após, pela injeção de ADR ou SAL. Os comportamentos foram registrados durante 30 minutos. Os resultados indicam que a injeção de ADR, assim como o bloqueio de receptores a1 resulta em hiperfagia, por outro lado, o bloqueio de a2 ou de a1 e a2 simultaneamente não altera o comportamento ingestivo. O pré-tratamento do núcleo mediano da rafe com a prazosina, seguida da injeção de ADR, não foi capaz de causar um incremento na quantidade de alimento ingerido após cada um separadamente, embora a maior dose (40nmol) tenha reduzido a latência para iniciar o comportamento ingestivo. O pré-tratamento com a ioimbina ou com a fentolamina, seguido de ADR, bloqueou o comportamento ingestivo induzido pela ADR sozinha. O presente estudo reforça a ideia de que existe uma ativação tônica de a1-adrenoceptores no NMR, que ativa uma influência inibitória (provavelmente neurônios serotonérgicos) em áreas que controlam a ingestão de alimentos. A ADR, ao ativar receptores a2, leva a uma queda na disponibilidade de catecolamina endógena na sinapse, o que reduz a liberação de 5-HT e leva à hiperfagia.Abstract : The present study evaluated the involvement of a-adrenoceptors of the median raphe nucleus (MRN) in satiated rats, in the variables of food and water intake and non ingestive behaviours. Control animals were treated with saline (SAL) or adrenaline (ADR), injected into the MRN seven minutes after the injection of the vehicle used to solubilize the antagonists, propylene glycol (PLG) or SAL. The animals of the experimental groups were treated with an a-adrenoceptor antagonist, prazosin (a1, 20 or 40nmol) or yohimbine (a2, 20 or 40nmol) or phentolamine (non-selective a, 20 or 40nmol), followed (seven minutes after) by the injection of ADR or SAL. The behaviours were recorded for 30 minutes. The results indicate that the injection of ADR and the blockade of a1 receptors result in hyperphagia, on the other hand, blocking a2 or a1 and a2 simultaneously does not change feeding behaviour. Pretreatment of the MRN with prazosin, followed by the injection of ADR was not able to cause an increase in the amount of food ingested by each one, while the highest dose (40nmol) reduced the latency to start feeding. Pretreatment with phentolamine or yohimbine, followed by ADR blocks feeding induced by ADR itself. The present study reinforces the idea that there is a tonic activation of a1-adrenoceptors in the MRN, which activates an inhibitory influence (probably serotonergic neurons) in areas that control food intake. ADR activates a2 receptors, resulting in a decrease in the availability of endogenous catecholamines at the synapse, which reduces the release of 5-HT and leads to hyperphagia

Differential roles of specific sub-regions of the longitudinal axis of the hippocampus in the behavioural and neurogenesis responses to stress and antidepressant drugs

Accumulating evidence suggests that the hippocampus is functionally segregated along its longitudinal axis into a dorsal (dHi) and a ventral sub-region (vHi). Indeed, recent gene expression studies suggest that the hippocampus has a gradient of gene expression and that the area between the dHi and vHi, the intermediate hippocampus (iHi), may also be functionally independent, but it remains understudied. The hippocampus is also one of few brain regions where neurogenesis, the birth of new neurons, occurs throughout life and this process has been shown to play roles in learning and memory as well as in responses to stress and antidepressants. These diverse roles may be related to the functional segregation of the hippocampus along its longitudinal axis. Indeed, the dorsal hippocampus (dHi) plays a predominant role in spatial learning and memory, while the ventral hippocampus (vHi) is predominantly involved in the regulation of anxiety, a behaviour impacted by stress and chronic treatment with some antidepressants. In vivo studies have shown that chronic stress and chronic antidepressant treatment change neurogenesis preferentially in the vHi rather than the dHi. However, whether these findings are due to differential intrinsic sensitivities of neural progenitor cells (NPCs) resident in the dHi, iHi or vHi in response to the stress hormone corticosterone or in response to antidepressants is unknown. Moreover, the roles of the dHi, iHi and vHi in the behavioural responses to chronic stress, a risk factor for depression and anxiety disorders, and in the behavioural responses to acute and chronic antidepressant treatment have not yet been investigated. Thus, the aims of this thesis were to determine whether NPCs isolated from the dHi, iHi and vHi have differential intrinsic sensitivities in response to the stress hormone corticosterone, the glucocorticoid receptor agonist dexamethasone, and the antidepressant, fluoxetine. To this end, we isolated NPCs from the three hippocampal sub-regions and cultured them for 4 h or 4 days in vitro with either corticosterone, fluoxetine, or corticosterone with fluoxetine or for 7 days in vitro with either corticosterone or dexamethasone. Cell proliferation, neuronal differentiation and maturation, nuclear GR expression and cell viability were then assessed. Moreover, we also aimed to determine the roles of each hippocampal sub-region on emotional behaviours and neuroendocrine response under baseline conditions, chronic psychosocial stress conditions and under chronic antidepressant treatment conditions. To this end, we performed stereotaxic surgeries in C57BL/6 mice to lesion the dHi, iHi or vHi with ibotenic acid. After recovery, animals were submitted to emotional behaviour and neuroendocrine tests under baseline conditions, or after chronic psychosocial stress, or after acute and chronic fluoxetine treatment. As result, we determined for the first time that NPCs isolated from the iHi and especially vHi are more sensitive to the effects of long-term exposure (7 DIV) to corticosterone and dexamethasone. Long-term (7 DIV) corticosterone and dexamethasone exposure also reduced nuclear GR expression preferentially in cells from the vHi. Fluoxetine alone did not have any effect on cell proliferation or neuronal differentiation or maturation. However, fluoxetine prevented corticosterone-induced reductions in neuronal differentiation after 4 DIV treatment and these effects were observed predominantly in the iHi and vHi cell cultures. In vivo experiments showed that vHi lesions reduced anxiety under baseline conditions. Under chronic psychosocial stress conditions, iHi lesions increased stress-induced social avoidance and the lesion of all sub-regions prevented chronic stress-induced anxiety; dHi and vHi lesions prevented stress-induced anhedonia and only vHi lesions caused antidepressant-like behaviour in the forced swim test and promoted active coping behaviour. In the antidepressant experiment, vHi lesions prevented the antidepressant effects of acute fluoxetine treatment while iHi lesions prevented the antidepressant effects of chronic fluoxetine treatment, and both iHi and vHi lesions prevented the anxiolytic effects of chronic fluoxetine treatment. Taken together, these findings show for the first time that iHi and vHi NPCs have increased intrinsic sensitivity to longer term exposure to the stress hormone corticosterone, and that the vHi seems to be an important sub-region for antidepressant-like effects under chronic stress. Also, both the iHi and vHi but not the dHi seem to modulate the antidepressant and anxiolytic effects of fluoxetine

Inhibition of FKBP51 induces stress resilience and alters hippocampal neurogenesis

Stress-related psychiatric disorders such as depression are among the leading causes of morbidity and mortality. Considering that many individuals fail to respond to currently available antidepressant drugs, there is a need for antidepressants with novel mechanisms. Polymorphisms in the gene encoding FK506-binding protein 51 (FKBP51), a co-chaperone of the glucocorticoid receptor, have been linked to susceptibility to stress-related psychiatric disorders. Whether this protein can be targeted for their treatment remains largely unexplored. The aim of this work was to investigate whether inhibition of FKBP51 with SAFit2, a novel selective inhibitor, promotes hippocampal neuron outgrowth and neurogenesis in vitro and stress resilience in vivo in a mouse model of chronic psychosocial stress. Primary hippocampal neuronal cultures or hippocampal neural progenitor cells (NPCs) were treated with SAFit2 and neuronal differentiation and cell proliferation were analyzed. Male C57BL/6 mice were administered SAFit2 while concurrently undergoing a chronic stress paradigm comprising of intermittent social defeat and overcrowding, and anxiety and depressive -related behaviors were evaluated. SAFit2 increased neurite outgrowth and number of branch points to a greater extent than brain derived neurotrophic factor (BDNF) in primary hippocampal neuronal cultures. SAFit2 increased hippocampal NPC neurogenesis and increased neurite complexity and length of these differentiated neurons. In vivo, chronic SAFit2 administration prevented stress-induced social avoidance, decreased anxiety in the novelty-induced hypophagia test, and prevented stress-induced anxiety in the open field but did not alter adult hippocampal neurogenesis in stressed animals. These data warrant further exploration of inhibition of FKBP51 as a strategy to treat stress-related disorders.Fil: Codagnone, Martín Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Biología Celular y Neurociencia "Prof. Eduardo de Robertis". Universidad de Buenos Aires. Facultad de Medicina. Instituto de Biología Celular y Neurociencia; ArgentinaFil: Kara, Nirit. University College Cork; IrlandaFil: Ratsika, Anna. University College Cork; IrlandaFil: Rocha Levone, Brunno. University College Cork; IrlandaFil: van de Wouw, Marcel. University College Cork; IrlandaFil: Tan, Laura A.. No especifíca;Fil: Cunningham, Jacobi I.. No especifíca;Fil: Sanchez, Connie. No especifíca;Fil: Cryan, John F.. University College Cork; IrlandaFil: O'Leary, Olivia F.. University College Cork; Irland

The phase separation-dependent FUS interactome reveals nuclear and cytoplasmic function of liquid–liquid phase separation

Liquid–liquid phase separation (LLPS) of proteins and RNAs has emerged as the driving force underlying the formation of membrane-less organelles. Such biomolecular condensates have various biological functions and have been linked to disease. The protein Fused in Sarcoma (FUS) undergoes LLPS and mutations in FUS have been causally linked to the motor neuron disease Amyotrophic Lateral Sclerosis (ALS-FUS). LLPS followed by aggregation of cytoplasmic FUS has been proposed to be a crucial disease mechanism. However, it is currently unclear how LLPS impacts the behaviour of FUS in cells, e.g. its interactome. Hence, we developed a method allowing for the purification of LLPS FUS-containing droplets from cell lysates. We observe substantial alterations in the interactome, depending on its biophysical state. While non-LLPS FUS interacts mainly with factors involved in pre-mRNA processing, LLPS FUS predominantly binds to proteins involved in chromatin remodelling and DNA damage repair. Interestingly, also mitochondrial factors are strongly enriched with LLPS FUS, providing a potential explanation for the observed changes in mitochondrial gene expression in mouse models of ALS-FUS. In summary, we present a methodology to investigate the interactomes of phase separating proteins and provide evidence that LLPS shapes the FUS interactome with implications for function and disease

Desenvolvimento do controle cervical em crianças com paralisia cerebral

RESUMOO controle cervical é uma das primeiras aquisições motoras voluntária da criança. A disfunção motora na Paralisia cerebral pode ocasionar atraso no desenvolvimento do controle cervical e fixação de padrões posturais patológicos. O objetivo deste estudo foi de identificar os recursos disponíveis na literatura para aquisição do controle cervical e relacioná-los com o caso de uma criança que apresenta severo atraso do desenvolvimento motor. Foram avaliados os reflexos primitivos, as reações de retificação e equilíbrio, o grau de espasticidade, a função motora ampla e as habilidades funcionais. Observou-se presença de reflexos primitivos e espasticidade em todos os membros, deficiência ou ausência das reações de retificação e equilíbrio e limitação funcional muito severa. A obtenção de um desenvolvimento neuropsicomotor mais normal possível é o objetivo principal no tratamento de uma criança com paralisia cerebral. Observou-se escassez de estudos relacionados ao controle cervical, apesar de ser um precursor necessário para outras aquisições motoras e posturais

Função cognitiva e grau de severidade de dependência ao álcool em indivíduos com diagnóstico de síndrome de dependência alcoólica

As alterações comportamentais e neurocognitivas resultantes do uso abusivo do álcool, relacionadas à alta prevalência de indivíduos dependentes tornam o alcoolismo um problema de saúde pública. O presente estudo avaliou a função cognitiva e o grau de severidade da dependência ao álcool em indivíduos com diagnóstico da Síndrome da Dependência Alcoólica. Foi aplicada uma entrevista estruturada, além da Avaliação da Severidade da Dependência do Álcool (SADD) e do Mini-Exame do Estado Mental (MEEM). A amostra foi de 51 pacientes do sexo masculino, entre 27 e 64 anos. Observou-se que todos os pacientes que pontuaram abaixo do ponto de corte eram dependentes graves. Os resultados obtidos no presente trabalho demonstram suspeita de deterioração cognitiva nos dependentes graves do álcool, indicando a necessidade de implementação de estratégias para a prevenção e a importância da existência de centros de reabilitação