Acredita-se que quantidades elevadas de glutamato estejam relacionadas à neurobiologia da depressão e trabalhos recentes indicam que a quantidade de glutamato cortical está aumentada em pacientes depressivos quando comparada a indivíduos sadios. Dentre as estruturas corticais, o córtex pré-frontal medial ventral (CPFMv), dividido em infralímbico (IL) e pré-límbico (PL), tem sido mais frequentemente implicado no desenvolvimento de transtornos mentais, como a depressão. Considerando evidências de que o IL e o PL podem agir de forma diferente quanto ao controle emocional em resposta ao estresse, o presente trabalho visou avaliar a hipótese de participação da neurotransmissão glutamatérgica do CPFMv, IL e PL, no desenvolvimento das respostas comportamentais ao estresse de nado forçado, um modelo preditivo de efeitos antidepressivos. Para tal, investigamos os efeitos induzidos pela administração no IL ou no PL, de LY 235959, um antagonista dos receptores glutamatérgicos do tipo NMDA, em três momentos diferentes, em animais submetidos ao teste do nado forçado. A administração de LY 235959, no IL ou PL, produziu efeitos do tipo antidepressivo, sendo esse efeito sensível ao tempo de administração da droga em relação à exposição ao nado forçado. Sendo assim, foi observado efeito antidepressivo quando o bloqueio glutamatérgico no PL ocorreu imediatamente após o nado ou antes da re-exposição ao estresse; enquanto no IL, o tratamento promoveu efeito antidepressivo apenas quando administrado antes da re-exposição ao nado. Portanto, os resultados sugerem que a neurotransmissão glutamatérgica mediada por receptores NMDA no CPFMv contribui para o desenvolvimento de consequências comportamentais do estresse, de modo que o bloqueio desses receptores facilitaria a adaptação ao estresse e induziria efeitos do tipo-antidepressivo. Os resultados sugerem, ainda, que o PL e o IL participam de maneira semelhante na modulação desses processos. / It is believed that high amounts of glutamate are related to the neurobiology of depression. Recent studies indicate that the amount of cortical glutamate is increased in depressed patients compared to healthy subjects. Among the cortical structures, the ventral medial prefrontal cortex (CPFMv), divided into infralimbic (IL) and prelimbic (PL) has been most often implicated in the development of mental disorders, such as depression. Considering that IL and PL play different roles on the emotional control in response to stress, this study was aimed to evaluate the hypothesis that the activation of glutamate NMDA receptors within the CPFMv, IL and PL, would facilitate the development of forced swimming-induced behavioral responses, an animal model predictive of antidepressants effects. To this end, we investigated the effects induced by the administration in the PL or the IL of LY 235959, an antagonist of NMDA receptors, at three different times, in animals submitted to the forced swimming test. The administration of LY 235959, in the IL or PL, produced antidepressant-like effects, and this effect is sensitive to moment of drug administration in relation to exposure to forced swimming. Thus, the antidepressant-like effect was observed when blocking the NMDA blockade into the PL occurred immediately after swimming or before re-exposure to stress, whereas in the IL, such treatment promoted antidepressant-like effect only when administered before re-exposure to swimming. Therefore, the results suggest that the glutamatergic neurotransmission mediated by NMDA receptors in the CPFMv contributes to the development of behavioral consequences of stress, so that blocking these receptors would facilitate the adaptation to stress and induce antidepressant-like effects. The results also suggest that PL and IL may be similarly involved in modulating these processes.

Introdução: O fechamento do defeito e reforço com prótese por via aberta sempre foi o procedimento de escolha na hérnia ventral/incisional. A Cirurgia Minimamente Invasiva (CMI) mudou a maneira de preparar e dissecar a parede abdominal. Com o advento da laparoscopia iniciou-se a correção em ponte do defeito através da colocação e fixação intraperitoneal de tela. Entretanto, evidências científicas mostram os benefícios do fechamento do defeito e colocação retro muscular da prótese como melhor técnica cirúrgica. Objetivos: Demonstração de nova técnica cirúrgica com correção laparoscópica de hérnia incisional no paciente pós cirurgia bariátrica, com avaliação dos resultados peri-operatórios e impacto na qualidade de vida. Métodos: Entre outubro de 2012 e fevereiro de 2014, 15 pacientes em pósoperatório de cirurgia para tratamento da obesidade mórbida foram submetidos a correção laparoscópica de hérnia incisional na linha média. O procedimento constitiu-se no fechamento do defeito e aproximação da linha média através do uso de grampeador linear laparoscópico, com a criação de espaço retro muscular onde a tela é posicionada e fixada. A seleção dos pacientes foi feita a partir de pacientes com hérnia incisional em sua linha média pós cirurgia bariátrica. Mulheres grávidas, pacientes com câncer ou contraindicações clínicas foram excluídos. Resultados: Quatro eram homens e onze mulheres. A idade média dos pacientes foi 52,3 anos (39 - 67). O IMC médio da série foi de 42,68 kg/m2 (40,61 - 57) antes da cirurgia bariátrica e 29,2 kg/m2 (23 - 31,6) no momento da hernioplastia. Quanto ao tamanho, a média da largura foi de 4,98 cm (2,1 - 9) e comprimento de 14 cm (7,5 - 20,5), com área média de 71,4 cm2 (21 - 138,7). O tempo cirúrgico médio foi de 114,33 min (85 - 170 min) e a média de internação hospitalar foi de 1,4 dias (1 - 6). Não houve complicações intra-operatórias ou imediatas. Um paciente apresentou seroma tratado conservadoramente uma semana após a cirurgia e outro paciente apresentou coleção retro muscular infectada tratada por drenagem percutânea. Dois pacientes apresentaram recidiva 1 ano após o procedimento (13,3%). O Questionário de qualidade de vida (QOL) mostrou boa satisfação e melhora nas limitações com significância estatística. Conclusões: O estudo demonstrou uma nova técnica vídeocirúrgica factível, segura e com baixos índices de complicação para o tratamento da Hérnia Incisional (HI) no doente obeso pós cirurgia bariátrica. Ademais obteve um impacto significante em sua qualidade de vida / Background: Open suture and mesh reinforcement were the procedure of choice for ventral/Incisional hernia repair. The minimally invasive surgery (MIS) changed the way to dissect and prepare the anatomy of the abdominal wall. Laparoscopic approach with defect bridging and mesh fixation was described since 1993, but the concept of this procedure remains unchanged. Former evidences showed benefits with defect closure and retro-muscular mesh positioning as best surgical practice. Objectives: Demonstration of a new technique for laparoscopic correction of incisional hernias in patients submitted previously to bariatric surgery, along with the evaluation of its perioperative results and the impact in the quality of life (QOL). Methods: Between October 2012 and February 2014, 15 post bariatric surgery patients undergone laparoscopic midline incisional hernia repair. The procedure consisted in the use of a laparoscopic linear stapler to close the defect and approximate the midline, as well as creating a retro rectus space in which a mesh was deployed and fixated. Selection was based on incisional midline hernias post open bariatric surgery. Pregnant women, patients in the presence of cancer or with clinical contraindications were excluded. Results: Four patients were men and the other eleven women. The patients mean age was 52.3 years (range: 39 - 67). The mean BMI of the series was 42.48 kg/m2 (range: 40,61 - 57) before the bariatric procedure and 29.5 kg/m2 (range: 23 - 31.6) when the hernia repair was done. Regarding the size of the defects, the mean width was 4.98 cm (range: 2.1 - 9) and length of 14 cm (range: 7.5 - 20.5), the mean area was 71.4 cm2 (21 - 138.7). The mean surgical time was 114.33 min (range: 85 - 170), and the mean length of hospital stay was 1.4 day. No intraoperative or immediate postoperative complication or death occurred. One patient had a seroma treated conservatively one week after surgery and another had a retro muscular infection treated with percutaneous drainage. Two patients presented recurrence one year after the procedure (13.3%). QOL questionnaries showed satisfaction and improvement in limitations with statistically significance. Conclusions: The study showed a new laparoscopic technique for the treatment of incisional hernias in the obese patient post bariatric surgery. The procedure was feasible, safe and with low rates of complications, as well as statistically significant in the improvement of QOL

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No. of bitstreams: 2 Dissertação - Rodrigo Fernandes de Lima - 2015.pdf: 2077886 bytes, checksum: 41cc0e061b83ff79f5098eb054d1fcda (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2015-03-06 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The neonatal development is stimulated by various hormonal interactions. Environmental pollutants that mimic steroid hormones, such as bisphenol A (BPA) can cause changes in the pattern of development of the prostate, leading to lifelong lesions. The objective of this study was to determine whether neonatal exposure to BPA affects the development of prostate gerbils males and females. For this, the newborns were exposed to environmental levels (LBPA - 40 μ / kg / day) and high dose (HBPA - 4 mg / kg / day) of BPA, from 1st to the 7th day of life. On the eighth day, the prostatic complexes were collected and processed for morphological analysis, stereological and immunohistochemistry. It was observed through the three-dimensional reconstruction that in males the prostatic buds have elongated in a "V" form towards the ventral condensed mesenchyme (VMP). The stereological data of males showed a significant increase in the relative frequency of the mesenchymal compartment in the LBPA group compared to other groups (p ≤ 0.05). The AR-positive cells became significantly more frequent in the periurethral mesenchyme (PEM), ventral epithelial buds (VB) and muscle layer (SM) in the BPA group. There was a reduction in the frequency of PCNA-positive cells in the periurethral buds (PeB) and in the SM of the LBPA group. In females, the three-dimensional reconstruction showed that PeBs can emerge from one or both sides of the urethra and it was also visible a significant paraurethral mesenchyme (MAP) reduction in the BPA group. Only females of the HBPA group apparently presented paraurethral buds (PAB) more developed. In the LBPA group it was observed an increase in the AR-positive cells frequency in the PeM and a decrease of these cells in the PeB and mesenchyme paraurethral (PaM). In the HBPA group the AR-positive cells were more frequent in the PeM and PaB and reduced in PeB and PaM. PCNA-positive cells became significantly less frequent in the PaB and PaM of LBPA and HBPA groups. Regarding the ER-α positive cells in the group LBPA females showed a reduction in the immunoblots of PeM and MS, whereas in the group HBPA this reduction occurred only in the PaM. This study revealed that the postnatal development of the prostate of female gerbils occurs earlier and are morphologically distinct from what occurs in males of the same species. Furthermore, it can be seen that the BPA exerted a proliferative effect on the prostate gland of males and females with eight days of postnatal life, though females being more susceptible to this environmental chemicals. / O desenvolvimento neonatal é estimulado por diversas interações hormonais. Os poluentes ambientais que mimetizam hormônios esteróides, como o bisfenol-A (BPA), podem causar alterações no padrão de desenvolvimento da próstata, levando a lesões ao longo da vida. O objetivo deste estudo foi verificar se a exposição neonatal ao BPA afeta o desenvolvimento da próstata de gerbilos machos e fêmeas. Para isso, os recém-nascidos foram expostos a níveis ambientais (LBPA – 40 μ/kg/dia) e doses elevadas (HBPA – 4 mg/kg/dia) de BPA, do 1° ao 7º dia de vida. No oitavo dia, os complexos prostáticos foram coletados e processados para as análises morfológica, estereológica e imunohistoquímica. Com a reconstrução tridimensional observamos que nos machos os brotos prostáticos se alongaram em forma de “V” em direção ao mesênquima condensado ventral (VMP). Os dados estereológicos dos machos demonstraram um aumento significativo na frequência relativa do compartimento mesenquimal do grupo LBPA em relação aos demais grupos (p ≤ 0,05). As células AR-positivas tornaram-se significativamente mais frequentes no mesênquima periuretral (PeM), brotos epiteliais ventrais (VB) e camada muscular (SM) dos grupos tratados com BPA. Ocorreu uma redução na frequência de células PCNA-positivas nos brotos periuretrais (PeB) e na SM do grupo LBPA. Em fêmeas, a reconstrução tridimensional demonstrou que os PeBs podem emergir de um ou ambos os lados da uretra e também foi visível uma significativa redução do mesênquima parauretral (PaM) nos grupos tratados com BPA. Apenas as fêmeas do grupo HBPA apresentaram brotos parauretrais (PaB) aparentemente mais desenvolvidos. No grupo LBPA observou-se um aumento na frequência de células AR-positivas no PeM e uma diminuição destas células no PeB e mesênquima parauretral (PaM). No grupo HBPA as células AR-positivas tornaram-se mais frequentes no PeM e PaB, contudo sofreram redução no PeB e PaM. Células PCNA-positivas tornaram-se significativamente menos frequentes no PaB e PaM dos grupos LBPA e HBPA. Em relação às células ER-α positivas, nas fêmeas do grupo LBPA observou-se uma redução das imunomarcações no PeM e SM, enquanto que no grupo HBPA essa redução ocorreu apenas no PaM. Este estudo revelou que o desenvolvimento pós-natal da próstata de fêmeas de gerbilos é mais precoce e morfologicamente distinto do que ocorre nos machos da mesma espécie. Além disso, pode-se observar que o BPA exerceu um efeito antiproliferativo sobre a glândula prostática de machos e fêmeas com oito dias de vida pós-natal, sendo as fêmeas mais susceptíveis a este químico ambiental.

A área tegmental ventral (VTA) contém neurônios dopaminérgicos do grupamento A10 e envia projeções muito densas para o estriado ventral. Esta circuitaria está crucialmente envolvida em mecanismos de recompensa. Recentemente, a organização destas projeções foi reexaminada por Ikemoto S. (Brain Res. Rev., 56:27-78, 2007), em um estudo de rastreamento retrógrado minucioso, sendo proposto a subdivisão destas projeções em um sistema dopaminérgico mesoestriatal ventromedial que inerva a concha medial do accumbens e o tubérculo olfatório medial, e um sistema dopaminérgico mesoestriatal ventrolateral que inerva o cerne e a concha lateral do accumbens e o tubéculo olfatório lateral. Afim de complementar o conhecimento destas projeções, no presente estudo elas foram examinadas com a técnica anterógrada da leucoaglutinina do Phaseolus vulgaris. Nossos resultados indicam que há um extenso embricamento dos campos terminais estriatais inervados por diferentes setores/núcleos da VTA e reforçam a noção de que as eferências da VTA podem ser subdivididas em um sistema mesoestriatal ventromedial e um sistema mesoestriatal ventrolateral. Eles revelam ainda que as projeções da VTA para o estriado ventral têm uma organização topográfica médio-lateral mais complexa do que previamente reconhecido, a faixa médio-lateral do estriado ventral inervada depende de uma combinação da região médio-lateral e dorsoventral da VTA. Assim, as regiões mais ventrais e mediais da VTA (correspondendo ao núcleo interfascicular) inervam os distritos mais mediais do estriado ventral (a concha dorsomedial do accumbens e a extremidade medial do tubérculo olfatório), e as regiões mais dorsais e laterais da VTA (correspondendo à região dorsolateral do núcleo parabraquial pigmentoso) se projetam para os distritos mais laterais do estriado ventral (o cerne lateral e a concha lateral do accumbens, o caudado-putâmen ventral e o tubérculo olfatório lateral). Por outro lado, as projeções da VTA para o estriado ventral não possuem uma organização topográfica rostrocaudal. Outro fato a ser destacado é que a organização das projeções mesoestriatais da VTA lembra o padrão das projeções córticoestriatais, sendo observado no estriado, além de um campo terminal principal, pequenos focos isolados de marcação. / The ventral tegmental area (VTA) contains dopaminergic neurons of the A10 group and sends dense projections to the ventral striatum. This circuitry is critically involved in reward mechanisms. Recently, the organization of these projections was reexamined by Ikemoto S. (Brain Res. Rev., 56:27-78, 2007) in a detailed retrograde tracing study, being proposed that these projections can be subdivided into two main systems, a ventromedial mesostriatal dopaminergic system that innervates the medial shell of the accumbens and medial olfactory tubercle, and a ventrolateral mesostriatal dopaminergic system that targets the core and lateral shell of the accumbens and lateral olfactory tubercle. In order to complement these data, in the present study the VTA mesostriatal projections were examined with a sensitive anterograde tracing technique using the Phaseolus vulgaris leucoaglutinin. Our results indicate that there is an extensive overlap of terminal fields innervated by different sectors / nuclei of the VTA and reinforce the notion that VTA efferents can be subdivided into a ventromedial and a ventrolateral mesostriatal system. They also show that the VTA projections to the ventral striatum have a mediolateral topographical organization more complex than previously acknowledged. In fact, projections along the mediolateral dimension of the ventral striatum depends on a combination of the mediolateral and dorsoventral axis of the VTA. In other words, the most ventral and medial parts of the VTA (corresponding to the interfascicular nucleus) innervates the most medial districts of the ventral striatum (corresponding to the dorsomedial shell of the accumbens and medial tip of the olfactory tubercle), and the most dorsal and lateral parts of the VTA (corresponding to the dorsolateral region of the parabrachial pigmented nucleus) project to the most lateral districts of the ventral striatum (lateral core and lateral shell of the accumbens, ventral caudate-putamen and lateral olfactory tubercle). Moreover, VTA projections to the ventral striatum do not seem to have a rostrocaudal topographical organization. It is also of note that the organization of the VTA mesostriatal projections shares features with cortico-striatal projections, in the sense that both fiber systems have a main terminal field and also give rise to small, scattered isolated foci of terminal labeling.

Il y a longtemps qu’on a attribué à l’hippocampe un rôle central dans la mémoire, mais ce n’est pas son unique rôle. Un nombre grandissant d’études attestent que l’hippocampe peut être séparé en deux régions, dorsale et ventrale, qui sont fonctionnellement différentes. La partie dorsale de l’hippocampe est responsable du rôle classique dans la mémoire spatiale et contextuelle, alors que la région ventrale de l’hippocampe est importante dans l’expression de l’anxiété et de la motivation, entre autres. Les projections des noyaux du raphé, l’unique source d’afférences sérotoninergiques de l’hippocampe, auraient un rôle régulateur sur ses fonctions, dont le comportement anxieux. Toutefois, les fonctions de la projection sérotoninergique raphé-hippocampe ventral ne sont pas entièrement caractérisées et les différents rôles des sous-populations de neurones sérotoninergiques au sein même de la projection raphé-hippocampe ventral sont peu connus. Dans ce projet de recherche, nous avons utilisé des tests comportementaux et des outils optogénétiques, afin de déterminer le rôle de la projection sérotoninergique raphé-hippocampe ventral dans le comportement d’aversion. Notre hypothèse est que la sérotonine régule l’anxiété en agissant sur l’hippocampe ventral via cette projection. Nous démontrons entre autres que l’activation de la projection sérotoninergique raphé-hippocampe ventral induit une hausse de l’anxiété, mais spécifiquement chez les femelles. Nous démontrons aussi que l’activation de la projection réduit la locomotion. Nos données offrent un nouveau point de vue sur le rôle du raphé médian dans l’anxiété ainsi que sur l’importance du sexe dans l’expression du comportement anxieux. / It has been known for a long time that the hippocampus has a central role in memory, but it isn’t its sole function. A growing number of studies are showing that the hippocampus can be split in two regions, dorsal and ventral, that are functionally different. The dorsal part is responsible for the classic and well-known role of the hippocampus in spatial and contextual memory, while the ventral region is important for the expression of anxiety and motivation, among other roles. The only serotonergic input of the hippocampus are the raphe nuclei and it has been suggested that it has a regulatory effect over its functions, such as anxiety. Nonetheless, the functions of the raphe-ventral hippocampus serotonergic projection are not fully characterized and sub-populations of serotonergic neurons inside the projection itself aren’t known. In this research project, we used behavioral tests and optogenetic tools to determine whether the raphe to ventral hippocampus serotonergic projection is able to influence aversive behaviors. Our hypothesis is that serotonin regulates anxiety through its influence on the ventral hippocampus via the raphe-ventral hippocampus serotonergic projection. We found that optogenetic activation of the projection induces heightened anxiety, but only in female mice. Our data offer new insight as to how the median raphe regulates anxiety and the importance of sex in the expression of anxiety.

Les troubles anxieux comptent parmi les troubles psychiatriques les plus courants dans le monde, les femmes étant presque deux fois plus susceptibles que les hommes de recevoir un diagnostic de trouble d’anxiété au cours de leur vie. Les neurones sérotoninergiques (5-HT) du raphé médian sont fortement impliqués dans la régulation de l’humeur et de l’anxiété, mais les substrats neuronaux sous-tendant les différences liées au sexe dans l’anxiété sont encore largement méconnus. L'hippocampe ventral (HPv), une région qui a été décrite comme un modulateur majeur de l'anxiété, entre autres grâce à ses communications oscillatoires avec d'autres zones cérébrales, reçoit des afférences denses de 5-HT des noyaux du raphé. Des résultats préliminaires obtenus par notre laboratoire montrent que l’activation optogénétique des neurones 5-HT du raphé qui projettent à l’HPv influence le niveau d’anxiété des souris femelles, mais pas des mâles. En se basant sur ces résultats, l’objectif de mon projet est d’explorer les causes de ce dimorphisme sexuel de la voie raphé-HPv dans l’anxiété. J’analyserai l’expression du marqueur d’activation c-Fos après un test d’anxiété, avec ou sans activation optogénétique de la voie 5-HT raphé-HPv. Notre hypothèse est qu’il existe une différence mâle-femelle dans l’excitabilité des neurones 5-HT projetant à l’HPv. Les résultats obtenus permettront de mettre en lumière i) l’expression de c-Fos dans les neurones 5-HT qui projettent à l’HPv en conditions basales (eYFP) chez les mâles et femelles et ii) la différence dans l’expression de c-Fos après activation optogénétique de notre population d’intérêt chez les mâles et femelles. Nous démontrons que l’activation optogénétique de la voie 5-HT du raphé projetant à l’HPv augmente les comportements anxieux, seulement pour les souris femelles. Nous démontrons aussi que l’activation de cette projection diminue l’activité locomotrice. Par ailleurs, les comportements anxieux semblent activer différemment les sous-régions du raphé en fonction du sexe. Ce travail contribue à une meilleure compréhension des mécanismes sous-jacents au rôle de la voie 5-HT du raphé projetant à l’HPv dans la modulation différentielle des comportements d’anxiété selon le sexe. / Anxiety disorders rank among the most common psychiatric conditions worldwide, with women being nearly twice as likely as men to receive a diagnosis of an anxiety disorder during their lifetime. Serotonergic neurons (5-HT) in the median raphe are heavily involved in regulating mood and anxiety, but the neuronal substrates underlying sex-related differences in anxiety are still largely unknown. The ventral hippocampus (vHP), a region described as a major modulator of anxiety, including through oscillatory communication with other brain areas, receives dense inputs of 5-HT from the raphe nuclei. Preliminary results from our laboratory indicate that optogenetic activation of 5-HT neurons projecting to the vHP influences the level of anxiety in female mice but not in males. Building upon these findings, the aim of my project is to explore the causes of this sexual dimorphism in the raphe-vHP pathway related to anxiety. I will analyze the expression of the c-Fos activation marker after an anxiety test, with or without optogenetic activation of the raphe-vHP 5-HT pathway. Our hypothesis is that there is a male-female difference in the excitability of 5-HT neurons projecting to the vHP. The results obtained will shed light on i) c-Fos expression in 5-HT neurons projecting to the vHP under baseline conditions (eYFP) in males and females, and ii) the difference in c-Fos expression after optogenetic activation of our population of interest in males and females. We demonstrate that optogenetic activation of the raphe-vHP 5-HT pathway increases anxiety behaviors, only in female mice. We also show that activation of this projection decreases locomotor activity. Furthermore, anxiety behaviors appear to activate different subregions of the raphe depending on sex. This work contributes to a better understanding of the underlying mechanisms of the role of the raphe-vHP 5-HT pathway in the differential modulation of anxiety behaviors based on sex.

Les neurones dopaminergiques (DA) de l’aire tegmentale ventrale (VTA) sont influencés par différents stimuli comme des récompenses naturelles et d’autres stimuli moins physiologiques tels que les drogues d’abus. Ces drogues agissent en détournant les mécanismes d’apprentissage qui sous-tendent normalement la motivation pour des renforçateurs naturels. Les neurones DA, en conditions physiologiques, sont subtilement régulés par une balance entre tonus GABA et glutamatergique. Ils sont soumis à de multiples sources inhibitrices dont le noyau accumbens, les interneurones locaux ou les neurones GABA de la queue de la VTA (tVTA). Le glutamate est également important dans leur modulation. Il contrôle leur activité en bursts, qui est le mode de décharge le plus efficace pour libérer de la dopamine et coder des informations associées à la récompense. Il permet des adaptations synaptiques à long terme qui se sont révélées importantes dans la prise de drogue. La connaissance des facteurs endogènes qui contrôlent l’excitabilité des cellules DA de la VTA est essentielle à la compréhension des processus physiologiques (recherche de plaisir…) mais aussi pathologiques (addiction…). L’objectif de mon travail a été de comprendre les circuits de régulation des neurones DA en conditions physiologiques et lors de l’exposition à la morphine. Dans un premier temps, nous avons étudié les mécanismes de régulation des neurones DA par la formation hippocampique ventrale incluant le subiculum ventral et l’aire CA1 ventrale (vSUB/CA1). Grâce à l’utilisation d’approches d’électrophysiologie in vivo chez le rat anesthésié, nous avons montré que le vSUB/CA1 exerce un contrôle excitateur glutamatergique des neurones DA. Nous avons mis en évidence que cette voie vSUB/CA1-VTA est polysynaptique, faisant intervenir le BNST comme relais. J’ai aussi pu confirmer le rôle fonctionnel de la tVTA en tant que nouvelle structure GABA modulant l’activité des neurones DA, renforçant ainsi l’idée d’une balance entre tonus GABA et glutamatergique régulant les neurones DA in vivo.La deuxième partie de ma thèse a consisté en l’étude des circuits neuronaux à l’origine des effets excitateurs de la morphine sur les neurones DA de la VTA in vivo. L’hypothèse actuelle est que la morphine excite les neurones DA par un mécanisme de désinhibition en inhibant les neurones GABA de la VTA. Grâce à l’utilisation d’approches multiples, nous avons proposé un nouveau circuit expliquant les effets de la morphine. Ces effets sont la conséquence d’une modification de la balance GABA/glutamate par la morphine. Elle se traduit par une diminution du tonus GABA et d’une augmentation du tonus glutamatergique. Enfin, nous avons pu démontrer qu’une seule exposition à la cocaïne augmente l’activité de base des neurones DA. Chez ces animaux, les effets excitateurs de la morphine sont potentialisés confirmant ainsi l’hypothèse que l’amplitude de l’activation des neurones DA par la morphine dépend de leur état d’excitabilité. / Dopaminergic (DA) neurons of the ventral tegmental area (VTA) are influenced by several stimuli such as natural rewards or drugs of abuse. Drugs shunt learning mechanisms which underlie motivation for natural reinforcers. Under physiological conditions, DA neurons are regulated by a balance between GABA and glutamatergic inputs. They receive several inhibitory inputs especially from the nucleus accumbens, VTA local interneurons and GABA neurons of the tail of the VTA (tVTA). Glutamate is also important in modulating DA neuron activity. It controls their bursting activity which is the most efficient way to release dopamine and to encode reward-associated informations. It allows long term synaptic adaptations important for addiction. Knowing how these endogenous factors control VTA DA neuron excitability is essential to understand physiological (search for pleasure…) and pathological (drug addiction…) processes.In the first part of my thesis, we studied the regulation of the VTA by the hippocampal formation including the ventral subiculum and the ventral CA1 area (vSUB/CA1). Using electrophysiological approaches in anesthetized animal, we showed that the vSUB/CA1 controls VTA DA neurons and that this input is glutamatergic. We also demonstrated that the vSUB/CA1-VTA pathway is polysynaptic implicating the BNST as a relay. I also confirmed the inhibitory control of the VTA by tVTA, new GABA input to DA neurons. Thus, in vivo, DA neurons are regulated by a balance between GABA and glutamatergic inputs. The second part of my research consisted in studying the neuronal circuits underlying excitatory effects of morphine on VTA DA neurons in vivo. The actual hypothesis is that morphine excites DA neurons by a disinhibition mechanism inhibiting VTA GABA neurons. Using several approaches (electrophysiological approaches in anesthetized animal, tract-tracing methods), we proposed a new circuitry explaining morphine effects. These excitatory effects result from a modification of the balance between GABA and glutamatergic inputs with a decrease of the GABA tone and an increase of the glutamatergic tone. Finally, we demonstrated that an acute cocaine exposure increases DA neuron activity. In animals exposed to cocaine, morphine excitatory effects are potentiated. This last experiment confirms the hypothesis that the amplitude of morphine-induced activation of VTA DA neurons depends on their excitability state.

Cette thèse a comme objectif l’étude des processus de plasticité du réseau bulbo-spinal respiratoire après une lésion spinale cervicale unilatérale en C2, qui induit une interruption de la majorité des fibres respiratoires. Cette étude est réalisée par une approche de traçage de voies, couplée à une approche immunohistochimique, biochimique et électrophysiologique.La lésion latérale chronique induit dans la région sus-lésionnelle C1/C2 une diminution du nombre de fibres bulbo-spinales marquées et de la surface de la substance blanche. Nous observons cependant une augmentation du nombre de fibres repoussant dans la substance grise, y compris de terminaisons axonales, ainsi qu’une augmentation du nombre de neurones respiratoires se projetant vers les noyaux phréniques en C3/C4. Suite à la lésion, une sous-population de neurones respiratoires axotomisés exprime des marqueurs de réponse post-lésionnelle.Ces processus de plasticité pourraient contribuer à la récupération fonctionnelle. / The aim of this thesis was to study the anatomical and cellular plasticity processes of bulbospinal respiratory pathways after a unilateral cervical spinal injury C2, which leads to an interruption of the respiratory fibers. This study used an approach of anterograde and retrograde labeling, coupled with immunohistochemical, biochemical and electrophysiological methods.The chronic lateral lesion induced in sus-lesional area C1/C2 a decreased of number of bulbospinal fibers and a decreased white matter, but an increased number fibers sprouting in the gray matter, including axon terminals, and an increased number of respiratory neurons projecting to the phrenic nuclei in C3/C4. Following the lesion, a sub-population of axotomized respiratory neurons express markers of cell body post-lesion response. These processes of plasticity could contribute to functional recovery.

Tout d’abord, nous avons démontré l’origine périphérique de la corticostérone après l’administration d’un stress aigu. Pour cela, nous avons utilisé un modèle de souris déficient en transporteur de corticostérone : Corticosterone binding-globulin (Cbg-/-). Ensuite, nous avons déterminé si les effets rapides du stress sur le rappel mnésique dépendaient de mécanismes non-génomiques. Nous avons précisé si ces effets étaient médiés par les récepteurs aux minéralocorticoïdes (MR) ou aux glucocorticoïdes de l’hippocampe. Dans ce but dans un premier temps, nous avons injecté un complexe macromoléculaire de corticostérone (Cort-3CMO-BSA) qui ne franchit pas la membrane cellulaire pour évaluer l’implication de mécanismes membranaires. Dans un deuxième temps nous avons administré dans l’hippocampe dorsal (HD) ou ventral (HV), 15 minutes avant le stress, l’antagoniste MR (RU 28318) et l’antagoniste GR (RU 38486) et nous avons évalué les performances mnésiques à 15, 60, 105 et 120 minutes après le stress. En effet ces délais ont été choisis selon l’apparition de pics de corticostérone induit par le stress, mesurés par microdialyse, dans l’HD et l’HV.Les principaux résultats obtenus sont : i) les souris Cbg -/- ne présentent pas de déficit mnésique 15 min après l’administration d’un stress aigu, contrairement aux souris contrôles qui ont un déficit mnésique important; ii) De même, l’administration de métyrapone (un inhibiteur de synthèse de la corticostérone) prévient des effets rapides du stress sur la mémoire; iii) Nous avons démontré que les effets rapides délétères sont médiés par des récepteurs membranaires, puisque l’injection de Cort-3CMO-BSA dans l’HD produit des effets similaires au stress aigu. De plus, l’effet de l’injection du complexe Cort-3CMO-BSA n’est pas bloqué par l’injection systémique d’anisomycine (un inhibiteur de synthèse protéique) nous avons montré que les récepteurs membranaires aux glucocorticoïdes de type MR sont responsables des effets cognitifs rapides du stress et de la cort-3CMO-BSA sur le rappel mnésique ;iv) Dans l’HD, l’injection du RU 28318 bloquait les effets délétères du stress quand les performances mnésiques étaient évaluées 15 min après le stress, mais non aux délais plus longs. Au contraire, le RU 38486 prévenait les déficits mnésiques quand les performances étaient évaluées à 60 mais non à 105 min après le stress. Dans l’HV, le schéma opposé est observé puisque l’injection du RU 38486 est dénuée d’effet quand il est injecté à 60 min après le stress mais il bloque les déficits mnésiques induits 105 min après le stress. L’implication des récepteurs MR et GR et l’efficacité de leur antagoniste semble dépendant de l’évolution de la concentration de corticostérone au cours du temps dans l’HD et l’HV.Pour conclure, notre étude a mis en évidence que le stress aigu diminue le rappel mnésique hipocampo-dépendant par l’intermédiaire d’un mécanisme de “switch” impliquant les récepteurs MR puis GR de l’HD à des délais plus courts et ensuite seulement les récepteurs GR de l’HV à des délais plus long. / We first showed the peripheral origin of corticosterone after an acute stress administration (electric foot-shocks) using corticosterone binding globulin-deficient mice (Cbg -/-). Then, we intended to determine if the rapid effects of stress on memory retrieval depended on non-genomic mechanisms and in a further step to precise whether such effects are mediated by mineralocorticoid (MR) or glucocorticoid receptors (GR) in the hippocampus. To that aims, we first injected a macromolecular complex of corticosterone (Cort-3CMO-BSA) that cannot cross the cell membrane to assess the involvement of membrane mechanisms. In a second step, we injected 15 minutes before stress delivery either in the dorsal (DH) or ventral (VH) hippocampus the MR antagonist (RU 28318) and GR antagonist (RU 38486) and evaluated memory at 15, 60, 105 and 120 minutes after stress delivery. Indeed, these delays were chosen according to the occurrence of stress-induced corticosterone peaks measured by microdialysis in DH and VH.The main results obtained in this study are: i) Cbg -/- mice are not affected by stress delivery occurring 15 minutes before memory testing, in contrast wild-type control mice which exhibited an important memory retrieval deficit; ii) Similarly, the rapid effects of stress on memory could be prevented by the systemic injection of metyrapone (a corticosterone synthesis inhibitor); iii) We showed that the rapid (15min) deleterious of stress on memory are mediated by membrane receptors, since the injection of Cort-3CMO-BSA in the DH produced similar effects as stress delivery. Moreover, the effect of the Cort-3CMO-BSA complex is not blocked by systemic injection of anisomycin (a protein synthesis inhibitor); iv) In DH, the injection of RU 28318 blocked the deleterious effects of stress when testing occurred 15 min after stress but not for longer delays. In contrast, RU 38486 prevented memory retrieval impairments when performance was evaluated at 60 but not at 105 min after stress. In addition, the opposite pattern was observed in VH since RU 38486 was denied of any effects when injected at 60 min but blocked the stress-induced memory impairments at the 105 min post-stress delay. The involvement of MR and GR receptors and consequently the efficiency of their antagonists seem to depend on the time-course evolutions of stress-induced corticosterone rises within the DH and VH.In conclusion, our study evidenced that acute stress impairs hippocampus-dependent memory retrieval via a switch mechanism involving the MR then GR in DH at shorter delays and then only GR in VH at longer delay.

O processamento visual se dá por duas vias, Dorsal (localização/movimento) mobilizada por TRS (tempo de reação simples), e Ventral (forma/cor) mobilizada por TER (tempo de reação escolha). Apresentamos uma nova abordagem para se investigar a distribuição dos recursos atencionais. Os métodos psicofísicos vigentes amostram repetidas vezes poucos pontos. Optou-se por amostrar muitos pontos na tela do computador poucas vezes, obtendo-se amostragem de uma grande área. Obteve-se um mapa de detalhamento da distribuição atencional. Experimentos de atenção voluntária: I. Tarefa de TRS, mobilizando a via Dorsal. Na situação de atenção difusa. II. TRE, mobilizando a via Ventral. Os estímulos possíveis diferiam na cor e foram respondidos ao se pressionar um botão, atenção difusa. III. TRE, focando-se a atenção em duas molduras, caracterizando atenção dividida. Os resultados demonstraram um favorecimento do hemicampo inferior para a TRS e um favorecimento do hemicampo superior para TER. Apareceram dois focos na atenção dividida fortalecendo a hipótese da divisão atencional. / Visual processing has two pathways: Dorsal (localization/movement) mobilized for Simple Reaction Time tasks (SRT); Ventral (shape/color) mobilized for Choice Reaction Time tasks (CRT). We presented an approach to investigate visual attentional resources. Usual psychophysical methods sample many times few points. We opted to sample many points few times aiming to enlarge the sampled visual field. It was obtained major details of the attentional distribution. Voluntary attention task: I. SRT, for Dorsal pathway. Stimuli were different in color answered triggering a button, in a diffusion attention paradigm. II. CRT, for Ventral pathway. Stimuli were two different color answered by triggering a button for each color in a diffuse paradigm. III. CRT, experimental subject instructed to focus attention in two frames for a splitted attention paradigm. Results showed anisotropy in the diffuse attention distribution, favouring the lower hemifield for SRT and superior hemifield for CRT. The splitted attention paradigm evidenced the presence of two attentional focuses.