Made available in DSpace on 2015-03-13T17:10:46Z (GMT). No. of bitstreams: 1 JudicleideAN_DISSERT.pdf: 1718775 bytes, checksum: 1c64b7a22a787d96b10f62b600bd2ba2 (MD5) Previous issue date: 2011-04-07 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / This research has as an empirical universe, the productive territory of red ware in the Serid? region of Rio Grande do Norte. In the last years this territory has gone through a process of appropriation that has been substantially changing the environmental and social dynamism of the place. However, the industry of red ware has been focusing in some areas, mainly, in the county of Parelhas and Carna?ba dos Dantas. From this point of view, the aim of this work consists in analyze the use of these areas by the red ware industry and the transformations occurred with the expansion of the number of industries and the productivity raise, that requires bigger amounts of earthenware and wood, resources that are low in referred territory. As the result of this process, the suitable alternative has been to acquire inputs in other Rio Grande do Norte counties, as well as in Para?ba counties. To reach the proposed objective, the methodology of this work was consisted of bibliographic and empirical research, regarding the occupation that this activity covers in the Serid? region. From the information obtained during the research, it can be stated that the inputs to the production execution in the red ware industry are acquired in the geographic nearby lands. The analysis of the stages of the production(acquisition of raw material, production and commercialization) showed that the activity acts in a continuous area, having as principal consumer market other northeastern states and the state of Par?. The present study revealed that the pottery activity is set as untenable, because of non-stopping use of the argil and wood, resources that are vanishing from the area, which consume causes a many problems such as deforestation and erosion. Besides, the sale of productive lands for the red ware industries makes harder its good use by the familiar agriculturists in the development of agriculture and cattle raising activity, which for many times is the main economic activity of the place. The precariousness reveals in the constant accidents at work, that most of them are neglected by the local authorities, without any penalty to the industries. Therefore, the industry of red ware in Serid? uses the territory as a resource, leaving its environmental problems that my compromise the quality of life of the actual and future generations / Esta pesquisa tem como universo emp?rico, o territ?rio produtor de cer?mica vermelha no Serid? potiguar. Nos ?ltimos anos esse territ?rio passou por um processo de apropria??o que tem alterado substancialmente a din?mica social e ambiental do lugar. No Serid?, a ind?stria de cer?mica vermelha tem se concentrado em algumas ?reas, sobretudo, nos munic?pios de Parelhas e Carna?ba dos Dantas. Nesta perspectiva, o objetivo desse trabalho consiste em analisar o uso do territ?rio pela ind?stria de cer?mica vermelha e as transforma??es ocorridas com a expans?o no n?mero de ind?strias e no aumento da produtividade, o que requer maiores quantidades de argila e de lenha, recursos escassos no referido territ?rio. Em decorr?ncia desse processo, a alternativa encontrada tem sido adquirir os insumos em outros munic?pios do Rio Grande do Norte, como tamb?m em munic?pios paraibanos. Para alcan?ar o objetivo proposto, o encaminhamento metodol?gico envolveu pesquisa bibliogr?fica e emp?rica, considerando a espacializa??o que essa atividade abrange no territ?rio seridoense. A partir das informa??es obtidas durante a pesquisa pode-se afirmar que os insumos para a realiza??o da produ??o na ind?stria de cer?mica vermelha s?o adquiridos no seu entorno geogr?fico. A an?lise das etapas do circuito de produ??o (aquisi??o da mat?ria-prima, produ??o e comercializa??o) mostrou que esta atividade atua numa ?rea cont?nua, tendo como principal mercado consumidor os demais estados do Nordeste e o estado do Par?. O presente estudo revelou ainda que a atividade ceramista configura-se como insustent?vel, haja vista a recorr?ncia permanente ? argila e ? lenha, insumos escassos no territ?rio, cuja aquisi??o provoca uma s?rie de problemas como o desmatamento e a eros?o. Al?m disso, a venda dos solos f?rteis para as cer?micas dificulta o seu aproveitamento pelos agricultores familiares, no desenvolvimento das atividades agropecu?rias, que muitas vezes configura-se na principal atividade econ?mica da propriedade. A precariedade da atividade se revela nos constantes acidentes de trabalho, que na grande maioria, s?o negligenciados pelas autoridades locais, sem aplica??o de nenhuma penalidade ?s empresas. Assim, a ind?stria de cer?mica vermelha no Serid? usa o territ?rio de forma seletiva e excludente, deixando s?rias problem?ticas ambientais, as quais podem comprometer a qualidade de vida das atuais e futuras gera??es

Made available in DSpace on 2014-12-17T14:52:55Z (GMT). No. of bitstreams: 1 LucianaIS.pdf: 335332 bytes, checksum: 5f89f072ec91d24abe9ce4db952202cc (MD5) Previous issue date: 2006-05-19 / This study presents itself as a contribution to the solidification of the Natural Gas industry, within the scope of the development of new products. The goal of this paper is to analyze the factors that lead to the success of new products through the evaluation of the activities done during the process of development of these products in the Natural Gas sector. To achieve this goal a case study was done in a small company of this segment. At first, as a basis for the study, a bibliographical research was done with books, theses, dissertations, monographies, publications in national and international periodicals, congress annals and publications in the internet related to the subject. Afterwards, a case study was done, aiming at the acquisition of further knowledge about the real process of development of products in a small company of the Natural Gas sector, allowing for the performance of the evaluation. The case study was done at Gas Project and Systems do Brasil, a company that works with the development of electronic equipment to the conversion of car engines to natural gas, through direct observations and interviews with the person responsible for the development and management of products. Through the evaluation of the process it was observed that the activities related to it are done in an informal way and some activities are considered unnecessary for their success. The results also suggest an emphasis in the technological activities, something that was not observed in the activities related to the market. The instruments used in this evaluation prove to be efficient to evaluate the process of development of new products in other companies, including those of different areas. Taking into account the relevance of the studied theme to the strengthening of the Natural Gas industry, it is necessary to do further complementary studies / O presente estudo apresenta-se como uma contribui??o ? solidifica??o da Ind?stria de G?s Natural, no ?mbito do desenvolvimento de novos produtos. O objetivo deste trabalho foi analisar os fatores que conduzem ao sucesso de novos produtos, atrav?s da avalia??o das atividades realizadas durante o processo de desenvolvimento desses produtos, no setor de G?s Natural. Para atingir tal objetivo, foi realizado um estudo de caso em uma pequena empresa deste segmento. Para fundamentar o estudo, foi realizada, inicialmente, uma pesquisa bibliogr?fica em livros, teses, disserta??es, monografias, artigos em peri?dicos nacionais e internacionais, anais de congressos, publica??es dispon?veis na internet, relacionadas ao tema de interesse. Posteriormente, foi realizado o estudo de caso visando obter um maior conhecimento sobre um processo real de desenvolvimento de produtos, em uma pequena empresa, no setor de G?s Natural, permitindo a realiza??o da avalia??o. O estudo de caso foi realizado na Gas Project & Systems do Brasil, empresa que atua no desenvolvimento de equipamentos eletr?nicos para convers?o automotiva em G?s Natural, a partir de observa??es e entrevistas com o respons?vel pelo gerenciamento e desenvolvimento de produtos. A empresa em estudo ? a ?nica do Nordeste a fabricar equipamentos que comp?em o kit de convers?o. Atrav?s da avalia??o do processo foi observado que as atividades a ele relacionadas s?o realizadas de maneira informal e algumas delas s?o consideradas desnecess?rias para o sucesso dos mesmos. Os resultados sugerem, tamb?m, uma ?nfase nas atividades tecnol?gicas, o que n?o foi observado para as atividades ligadas ao mercado. Os instrumentos utilizados para esta avalia??o mostram-se eficientes para avaliar o processo de desenvolvimento de novos produtos em outras empresas, inclusive de diferentes ?reas. Diante da relev?ncia do tema em estudo para o fortalecimento da Ind?stria de G?s Natural, faz-se necess?ria a realiza??o de estudos posteriores que o complementem

Made available in DSpace on 2014-12-17T14:58:25Z (GMT). No. of bitstreams: 1 WaldecioSAN.pdf: 2259202 bytes, checksum: 5cc6fb8a72468793d81d509b30ee2013 (MD5) Previous issue date: 2007-03-02 / The present work deals with an evaluation of the environmental impacts arised from a typical ceramics industry located in the Serid? region of Rio Grande do Norte State. That region contains the largest State s producing basin of red ceramics. The district of Parelhas stands out as the largest producing nucleus. The studied company is located in the rural zone of Parelhas, it was selected as study object because it possesses a great part of the representative characteristics of the Region s ceramics park as a whole. Impacts produced at the implantation and operation phases of the Company had been evaluated, being this last phase subdivided in stages of the productive process. Among found adverse impacts, they are distinguished: losses in air quality, undesirable noises, microclimatic alterations, impoverishment of the ground, elimination of the vegetal covering, agricultural exodus, crisis in cattle agriculture and, superficial and underground water contamination, beyond risks ocupational diseases and industrial accidents. The Leopold s interactive matrix, that summarizes results of the work, was presented in form of 15 (fifteen) tables that display impacts classified in qualitative and quantitative way. Totally, 175 (one hundred and seventy-five) significant impacts produced by this Company had been identified, being 114 (one hundred and fourteen) negative, 38 (thirty-eight) positive and 23 (twenty-three) among mixed, indefinite and inert ones. In the work, before the evaluation of impacts properly said, it was constructed a diagnostic table of the ambient situation at a previous moment to implantation of the Company, elaborated on basis of inferences and historical researches. It was proposed still, mitigative steps for adverse impacts identified, as also elaborated a program to accompaniment and observing that the fulfilment of indicated mitigative steps guarantees. The final part of the work contemplates conclusions and suggestions that aim to influence positively the presented sight in terms of environmental management / O presente trabalho trata de uma avalia??o de impactos ambientais gerados por uma ind?stria cer?mica t?pica da regi?o do Serid? do Rio Grande do Norte. Essa regi?o abriga a maior bacia produtora de cer?mica vermelha do Estado, destacando-se o munic?pio de Parelhas como maior n?cleo produtor. A empresa estudada localiza-se na zona rural do munic?pio de Parelhas, foi escolhida como objeto de estudo por reunir boa parte das caracter?sticas representativas do parque cer?mico da Regi?o como um todo. Foram avaliados os impactos produzidos nas fases de implanta??o e opera??o da Empresa, sendo esta ?ltima fase subdividida em etapas do processo produtivo. Entre os impactos adversos encontrados, destacam-se: perdas na qualidade do ar, ru?dos indesej?veis, altera??es no microclima, empobrecimento do solo, elimina??o da cobertura vegetal, ?xodo rural, crise na agricultura e pecu?ria, contamina??o de ?guas superficiais e subterr?neas, al?m de riscos de doen?as profissionais e acidentes de trabalho. A matriz interativa de Leopold, que resume os resultados do trabalho, foi apresentada na forma de 15 (quinze) tabelas que exp?em os impactos classificados de modo qualitativo e quantitativo. No total, foram identificados 175 (cento e setenta e cinco) impactos significativos produzidos por essa Empresa, sendo 114 (cento e quatorze) negativos, 38 (trinta e oito) positivos e outros 23 (vinte e tr?s) entre mistos, indefinidos e neutros. No trabalho, antes da avalia??o de impactos propriamente dita, foi constru?da uma tabela de diagn?stico da situa??o ambiental num momento anterior ? implanta??o da Empresa, elaborada com base em infer?ncias e pesquisas hist?ricas. Foram propostas ainda, medidas mitigadoras para impactos adversos identificados, como tamb?m elaborado um programa de acompanhamento e monitoramento que garanta o cumprimento das medidas mitigadoras indicadas. A parte final do trabalho contempla as conclus?es e sugest?es que visem influenciar positivamente o quadro apresentado em termos de gest?o ambiental

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Made available in DSpace on 2015-12-03T18:33:10Z (GMT). No. of bitstreams: 1 Marcelo_Ricardo_Carneiro_Barros_Filho.pdf: 1162396 bytes, checksum: 2dbb9e68e0598b336a41e6081fb11993 (MD5) Previous issue date: 2014-06-25 / The objective of this work is to identify the variables related to the operational and market aspects that influence the Market Value of the companies from meat and derivatives segment listed in S??o Paulo Stock Exchange over the period 2007 until 2013. The study was developed from the perspective of two theoretical axles. The first was an analysis of Market Value contributions as a useful indicator for determining the fair market value created for shareholders and, therefore, constitute a solid basis for measurement of companies performance. The second was the efficient market hypothesis which considers the information s efficiency or the impact of certain information on pricing assets. The results produced by the model ratified some of the hypotheses in this research, both in individual significance as on some independent variable sign. In addition, the model presented global significance, given by F test, at 5%, with a coefficient of multiple determination adjusted of 9,22% / O objetivo deste trabalho ?? identificar as vari??veis relacionadas aos aspectos operacionais e conjunturais que influenciam o Market Value das empresas do segmento de carnes e derivados listadas na BM&FBovespa, no per??odo de 2007 a 2013. O estudo foi elaborado sob a perspectiva de dois eixos te??ricos. O primeiro foi uma an??lise das contribui????es do Market Value como um indicador ??til para determina????o do valor justo de mercado criado aos acionistas e, portanto, constituindo uma base s??lida para mensura????o do desempenho das empresas. O segundo foi a hip??tese de mercado eficiente que considera a efici??ncia da informa????o ou o impacto de determinadas informa????es na precifica????o dos ativos. O modelo especificado produziu resultados que ratificaram algumas hip??teses da pesquisa, tanto na signific??ncia individual, quanto no sinal de algumas vari??veis independentes. Al??m disso, o modelo apresentou signific??ncia global, dada pelo teste F, a 5%, com um coeficiente de determina????o m??ltiplo ajustado de 9,22%.

Made available in DSpace on 2015-12-03T18:35:09Z (GMT). No. of bitstreams: 1 Nilton_Cesar_Carraro.pdf: 896223 bytes, checksum: 8c0daf04f6bcf3e81b87cc842356e7fd (MD5) Previous issue date: 2007-07-30 / The study of the use of the management information in the decisions of the strategic disposition by the footwear Industry of Ja?? - SP - investigates the use of the management information in a systemic process. The population of the research was limited to the formal footwear Industry comprehending Ja?? and neighbouring cities, both located in the center-west of S??o Paulo State, which during several decades, cultivated this economical activity causing Ja?? to be renowned as the Women Footwear National Capital. As an incentive to the research the great entering of hand-made Asian products, mostly footwear, brings about some apprehension about the local Industry competitiveness condition, at first taking the research to revision of the techniques of strategical management which could make the systemic use of the management information evident in the search for competition advantages. Expecting to create a census, questionaires were both handed out as well as made available in the Internet, where only 41 Industries answered to the calling, translating what would be a census into an aleatory sample. After this gathering, the questionaire involving 24 questions on the structure and organization aspects, was then treated statistically, with the creation of frequency tables, to define the entries for the treatment of the Chi-Squared tests, homogeneity and independency - crossing a series of variants and testing the results obtained. In the search for the strategic disposition, it was possible to make it evident that factors related to the experience of the entrepreneurs, period of existence of the firms, and the fact of belonging to a footwear center, are the main tools in the generation of management information capable to help in the decisions of strategic disposition, however, issues such as the low number and qualification of administrative employees impair the organization structure of these Industries, jeopardizing the use this management information. Negative factors to the research were made clear through the analysis which points out the lack of planning and strategic controlling, the lack of information about competition, the lack of indicators which proves the business performance and mostly the lack of knowledge about skills and competences which must be created to guarantee the profits and the continuity of its future activities. As a main result of the research, it is understood that this area of business has management information, however, not enough to bear the necessary decisions in the strategic disposition of this Industry. / O estudo sobre a utiliza????o da informa????o gerencial nas decis??es de posicionamento estrat??gico pela ind??stria de cal??ados de Ja?? - SP procura investigar o uso das informa????es gerenciais dentro de um processo sist??mico. Delimitou-se a popula????o da pesquisa ?? ind??stria formal de cal??ados que comp??e o munic??pio de Ja?? e cidades circunvizinhas, ambas localizadas na regi??o centro-oeste do Estado de S??o Paulo, que ao longo de v??rias d??cadas cultivaram essa atividade econ??mica levando Ja?? a ser reconhecida como a Capital Nacional do Cal??ado Feminino. Como est??mulo ?? pesquisa, a grande entrada de produtos manufaturados vindos da ??sia, principalmente o cal??ado, gera uma inquieta????o sobre a condi????o de competitividade da ind??stria local, conduzindo a principio a pesquisa para revis??o de t??cnicas sobre gest??o estrat??gica que pudessem evidenciar o uso sist??mico da informa????o gerencial na busca de vantagens competitivas. Com a expectativa de se criar um censo, foram distribu??dos question??rios tanto pessoalmente como por meio da internet, onde apenas 41 ind??strias responderam ao chamado, traduzindo o que seria um censo em uma amostra aleat??ria. Ap??s essa coleta, o question??rio envolvendo 24 quest??es, abordando estrutura e aspectos organizacionais, passou a ser tratado estatisticamente, com a cria????o de tabelas de freq????ncia para defini????o das entradas para tratamento dos testes qui-quadrado, homogeneidade e independ??ncia - cruzando uma s??rie de vari??veis e testando os resultados obtidos. Na busca pelo posicionamento estrat??gico, pode-se evidenciar que fatores ligados ?? experi??ncia dos empres??rios, tempo de exist??ncia das empresas, e o fato de pertencer a um p??lo cal??adista, s??o as principais ferramentas na gera????o de informa????es gerenciais com poder de auxiliar nas decis??es de posicionamento estrat??gico, no entanto, quest??es como a baixa quantidade e qualifica????o dos empregados do setor administrativo prejudicam a estrutura organizacional dessas ind??strias, comprometendo negativamente a utiliza????o dessa informa????o gerencial. Fatores negativos a pesquisa foram evidenciados por meio das an??lises que apontam a falta de planejamento e controle estrat??gico, a falta de informa????es sobre a concorr??ncia, falta de indicadores que comprovam o desempenho empresarial, e principalmente a falta de conhecimento sobre habilidades e compet??ncias que devem ser geradas no intuito de garantir os lucros e continuidade de suas atividades futuras. Como resultado principal da pesquisa, percebe-se que o setor possui informa????es gerenciais, por??m, elas n??o s??o suficientes para suportar decis??es necess??rias no posicionamento estrat??gico dessa ind??stria.

Made available in DSpace on 2014-12-17T14:27:30Z (GMT). No. of bitstreams: 1 AndersonSS.pdf: 411955 bytes, checksum: 5e1635b0c0478f712655188f802072b8 (MD5) Previous issue date: 2007-04-23 / In the middle of modern social changes produced by globalization and capitalism, several markets have changed. States have left the direct coordination of these markets (chiefly public utility sector in the form of monopolies), introducing regulation in order to promote competition. These changes have affected natural gas industry by promoting competition as a key factor to the development and the increase of firms in this market. The regulatory reform of natural gas industry ocurred in EUA and Europe Union and it has produced its first results. In Brazilian context, Constitutional Amendment nbr. 09 and Federal Law nbr. 9.478/97 ( Petroleum Law ) opened the natural gas market to a broad range of private economic agents and they finished the monopoly over the industry before managed by Petrobras. The new regulatory framework of Brazilian natural gas industry has designed competition as a central element to the new form of managment of business and contractual relationships of this industry. Among the regulatory instruments, open access regulation in natural gas pipelines is directed to promote competition. The questions arised about its implementation in Brazilian context are studied in the present work, in which it is discussed the constitutional rules and principles are to be applied to the open access regulation within the theme of statal regulation of economy present in constitutional economic order / No movimento de mudan?as sociais capitaneados pelo capitalismo global e pelo discurso neoliberal, t?m sido promovidas no mundo reformas nos chamados setores de infra-estrutura (antes geralmente geridos de forma direta pelo Estado sob a forma de monop?lios) no sentido de se introduzir uma regula??o que promova a concorr?ncia. Desses setores a industria do g?s natural vem sofrendo reformas institucionais relevantes que procuram retirar-lhe caracter?sticas monopol?sticas e permitir, dessa maneira, o aumento dos agentes nesse mercado. Em alguns paises essas transforma??es na industria do g?s natural encontram j? seus resultados (EUA e Uni?o Europ?ia). O Brasil tem promovido reformas no setor de g?s desde a Emenda Constitucional n? 09 e a Lei 9.478/97, abrindo as portas do mercado brasileiro de petr?leo e g?s para os investimentos privados, criando um cen?rio onde a Petrobr?s n?o est? mais sozinha na execu??o de atividades da cadeia do petr?leo e g?s natural. Acabou-se, assim, com o monop?lio da execu??o das atividades da industria do petr?leo e g?s (foi mantido o monop?lio da titularidade), passando-se a introduzir nesses setores a interven??o pela regula??o, a regula??o econ?mica. Dentre as pautas de regula??o importante da ind?stria do g?s natural encontra-se o chamado livre acesso (open access) aos gasodutos de transporte, fazendo-se pensar a regula??o do livre acesso ? luz da ordem econ?mica da nossa Constitui??o e projetar as rela??es entre Estado e Economia, buscando desenhar o conjunto de regras e princ?pios que orientam a a??o reguladora e fundamentam a possibilidade constitucional do controle de estruturas pelo livre acesso no segmento de transporte de g?s natural

La prise volontaire de nicotine augmente l'excitabilité de la voie ILCx-BNST, entraînant une hyperactivité des neurones DA de l’ATV. Dans une première partie, l'objectif était d’étudier les neuroadaptations de la voie ILCx-BNST induites par l'auto-administration intraveineuse (AAIV) de nicotine. Les récepteurs cannabinoides CB1 contrôlent les propriétés renforçantes de la nicotine. Par conséquent, nous avons examiné le rôle des récepteurs CB1 du BNST. Nous montrons que l'acquisition de l’AAIV de nicotine est associée à une facilitation persistante de l'induction d’une potentialisation à long terme (LTP) CB1-dépendantes des synapses ILCx-BNST. La stimulation électrique du ILCx favorise également la persistance du comportement de recherche de nicotine pendant les périodes où la drogue n'est pas disponible. En outre, en utilisant la pharmacologie intra-BNST, nous montrons que la stimulation des récepteurs CB1 du BNST au cours de l’acquisition de lAAIV augmente la sensibilité aux stimuli associés à la nicotine. L’idée qu’il existe un appétit incontrôlable pour les aliments palatables, en dépit des conséquences négatives. Dans une seconde partie, notre projet a porté sur le rôle des neurones dopaminergiques (DA) de l’ATV dans la perception d’un stimulus aversif chez l’animal exposé au sucrose. Nos résultats indiquent que le sucrose augmente l'activité spontanée des neurones DA de la VTA. En outre, si un choc électrique provoque une inhibition presque complète de l'activité de VTA neurones DA chez les rats témoins, le sucrose perturbe la signalisation d'un stimulus aversif, indépendamment de l’état calorique du rat. / Learning mechanisms associated with active responding for nicotine enhanced the excitability of the ILCx-BNST pathway. The objective of this project was to better understand the involvement of the ILCx-BNST pathway in nicotine self-administration. Since the endocannabinoid system controls nicotine reinforcement and nicotine-induced synaptic modifications, we examined the role of CB1 receptors in the BNST. We showed that acquisition of nicotine IVSA was associated with a persistent facilitation of LTP induction at ILCx-BNST synapses. Behaviorally, electrical stimulation temporarily increased excessive responding to nicotine when nicotine was not available. Moreover, using intra-BNST pharmacology, we revealed that stimulation of BNST CB1 receptors enhanced sensitivity to nicotine-paired cue. In contrast, after a prolonged history of nicotine intake, it blocked drug-seeking in a reinstatement model of relapse. Drug addiction is partly due to the inability to stop using despite negative consequences. The hypothesis that palatable food induces similar uncontrolled consumption is becoming more widespread. As drug addiction is known to increases activity of VTA DA neurons, we aimed to examine whether exposure to sucrose would induce similar neuronal modifications and impair the capacity to respond to an aversive stimulus. We found that sucrose enhanced spontaneous activity of DA VTA neurons. In addition, while a footshock caused a nearly complete inhibition of activity of VTA DA neurons in control rats, sucrose disrupted signaling of an aversive stimulus. These modifications were independent from the caloric state of the rats.

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.