Os astrócitos são células conhecidas por sua capacidade dinâmica e versatilidade, participando não somente da manutenção da homeostase cerebral em condições fisiológicas, mas também respondendo em condições patológicas, como por exemplo, na encefalopatia hepática (EH). Esta patologia neurológica está associada principalmente à hiperamonemia, decorrente de uma falência hepática aguda ou crônica. A toxicidade da amônia no sistema nervoso central (SNC) é mediada por uma série de alterações celulares e metabólicas, principalmente nas células astrogliais. Nesse sentido, a busca por moléculas com potencial terapêutico no SNC é extremamente relevante. Trabalhos do nosso grupo mostraram que o resveratrol e o ácido lipoico, duas moléculas conhecidas pelos seus efeitos antioxidantes, modulam importantes funções gliais, relacionadas principalmente ao metabolismo glutamatérgico, à defesa antioxidante e à resposta inflamatória. Neste sentido, esta tese teve como objetivo avaliar os efeitos do resveratrol e do ácido lipoico em células astrogliais e neuronais expostas à amônia, assim como seus possíveis mecanismos protetores. Primeiramente, nós observamos que o resveratrol e o ácido lipoico foram capazes de prevenir as alterações induzidas pela amônia em células astrogliais C6, sobre parâmetros do metabolismo glutamatérgico, dentre os quais podemos destacar a captação de glutamato, a atividade da enzima glutamina sintetase (GS) e o conteúdo de glutationa (GSH). Além disso, o ácido lipoico também exerceu um efeito antiinflamatório nestas células, prevenindo a liberação de citocinas pró-inflamatórias (TNFα, IL- 1β, IL-6, IL-18) e da proteína S100B, através da diminuição da ativação do fator de transcrição NFκB. Nós também verificamos que a maioria dos efeitos protetores do resveratrol e do ácido lipoico foram dependentes da heme oxigenase 1 (HO1), uma enzima associada com a defesa celular em situações de estresse. Por fim, foram avaliados os efeitos do resveratrol e do ácido lipoico sobre células neuronais expostas à amônia. Novamente, ambos apresentaram um efeito benéfico, prevenindo tanto o aumento da produção de espécies reativas de oxigênio (ERO) quanto a diminuição do conteúdo de GSH induzidos pela amônia. Nas células neuronais, a proteína HO1 também participou dos efeitos protetores do resveratrol e do ácido lipoico. Em conjunto, esses resultados nos mostram que o resveratrol e o ácido lipoico são capazes de modular positivamente o funcionamento tanto de células astrogliais quanto de células neuronais em situações de hiperamonemia, compartilhando também alguns mecanismos de ação, como a indução da HO1. Este estudo in vitro sugere que o resveratrol e o ácido lipoico são potenciais agentes terapêuticos para doenças do SNC, as quais envolvam produção de espécies reativas e resposta inflamatória, como a EH. / Astrocytes are dynamic and versatile cells which participate in the maintenance of brain homeostasis in physiological conditions and also in response to pathological conditions, such as hepatic encephalopathy. This neurological disease is mainly associated with hyperamonnemia, resulting from acute or chronic liver failure. Ammonia toxicity in the central nervous system (CNS) is mediated by several cellular and metabolic alterations, primarily in astroglial cells. In this sense, the search for molecules with therapeutical potential for CNS becomes highly relevant. Our group has shown that resveratrol and lipoic acid, two molecules known for their antioxidant activities, are able to modulate important glial functions mainly related to glutamate metabolism, antioxidant defense and inflammatory response. In this sense, this study aimed to evaluate the effects of resveratrol and lipoic acid in astroglial and neuronal cells exposed to ammonia, as well as their possible protective mechanisms. Firstly, we observed that resveratrol and lipoic acid were able to prevent ammonia-induced alterations in C6 astroglial cells functioning, such as glutamate uptake, glutamine synthetase (GS) activity and intracellular GSH content. Moreover, lipoic acid also exerted an anti-inflammatory effect in C6 astroglial cells, preventing the ammonia-stimulated release of pro-inflammatory cytokines (TNF, IL-1β, IL-6, IL-18) and S100B protein, by decreasing the activation of the transcription factor NFκB. We also verified that the most protective effects of resveratrol and lipoic acid involved the heme oxygenase 1 (HO1), an enzyme associated with protection against stressful conditions. Finally, we evaluated the effects of resveratrol and lipoic acid on neuronal cells exposed to ammonia. Again, both showed beneficial roles, preventing the increase of reactive oxygen species (ROS) and decrease of GSH content induced by ammonia. In neuronal cells, HO1 also mediated the protective effects of resveratrol and lipoic acid. Taken together, these results show that resveratrol and lipoic acid are able to positively modulate the functioning of both astroglial and neuronal cells in hyperamonemmia conditions, sharing some mechanisms of action, such as HO1. This study in vitro suggests that resveratrol and lipoic acid may represent potential therapeutic agents for CNS, during oxidative and inflammatory damages, as the induced by ammonia.

O consumo de álcool tem sido considerado um problema de saúde pública. Entretanto, também existem evidências de eventuais benefícios do consumo leve a moderado de algumas bebidas alcoólicas, no que se refere a doenças crônicas não transmissíveis. As doenças periodontais, sendo a sexta doença crônica mais prevalente, também têm sido associadas ao consumo de álcool com resultados controversos. Esta tese avaliou, através de três artigos a relação entre consumo de álcool e doenças periodontais. O primeiro artigo de divulgação, tem por objetivo alertar a profissão a respeito do estado atual do conhecimento em relação a associação entre álcool e doenças periodontais. O segundo artigo é um estudo experimental em modelo animal que avaliou o efeito da dependência química álcool sobre desfechos periodontais. Os resultados não mostraram diferenças estatisticamente significativas na perda óssea alveolar e secreção de TNF-α. O terceiro artigo, também em modelo animal, abordou o consumo do vinho tinto e valeu-se de controles total, álcool a 12%, suco de uva e resveratrol. A análise de ocorrência de periodontite espontânea demonstrou que o vinho tinto tem potencial protetor para a perda óssea alveolar e secreção de TNF- α . Os resultados encontrados nessa tese são instigantes e estão em linha com a literatura que demonstra uma relação do tipo curva J entre álcool e doenças periodontais, na qual até um determinado nível, o fator comporta-se como protetor. Assim, essa relação deve ser considerada na abordagem clínica, sem incentivo ao consumo, mas compreendendo até onde este é tolerável e/ou benéfico no que se refere a doenças periodontais. / Alcohol consumption has been considered a public health problem. Otherwise, there is evidence of eventual benefits of a light to moderate consume of some alcoholic beverage, in relation to non-transmissible chronic disease. The periodontal diseases, being the sixth most prevalent chronic disease, also have been associated to alcohol consumption with controversial results. This thesis evaluated, through three articles the relationship between alcohol consumption and periodontal diseases. The first article has the objective of alerting the professionals about the actual knowledge about the relationship between alcohol and periodontal diseases. The second article is an experimental study in animal model which evaluated the alcohol dependence over periodontal outcomes. The results did not show statistically significant differences in alveolar bone loss and TNF- α secretion. The third article, also in animal model, studied the red wine consumption and used total controls, 12% alcohol, grape juice and resveratrol. The analysis of the occurrence of spontaneous periodontitis demonstrated that red wine has a protector potential for alveolar bone loss and TNF- α secretion. The results found in this thesis are curious and they are in line with the literature that demonstrates a relationship like J-curve between alcohol and periodontal diseases, until some level, the factor behave as protector. So, this relation must be considered in clinical approaches, without encouraging the consumption, but understanding how much is tolerable and/or benefit according to periodontal diseases.

Elevated level of lipogenic enzymes and overall lipogenesis have been reported in a wide variety of cancers and blocking the lipogenic pathway by chemical inhibitors or RNA interference causes tumor cell death by apoptosis which provides a strong rationale for targeting lipogenic pathway for the treatment and prevention of cancer however the exact role of lipogenesis as a cause, facilitator or consequence is not yet clearly understood. Therefore in this dissertation research, we set up to determine the mechanism of tumor cell death by inhibiting lipogenesis and to determine the role of increased lipogenesis in the breast cancer progression. In the first part of this study, we investigated the status of fatty acid synthase (FAS) gene which is regarded as the key lipogenic gene in fatty acid biosynthetic pathway and is responsible for the synthesis of lipid molecules by facilitating the condensation reaction between acetyl-CoA and malonyl-CoA in the presence of NADPH. We observed that normal breast epithelial cells MCF10A cells have very low level of FAS expression whereas breast cancer cell lines MCF7, MDA MB231 and MDA MB231 LM have significant overexpression. Next, we observed the similar trend of FAS overexpression in breast cancer stem-like cells (CSCs) isolated from the MCF7, MDA MB231 and MDA MB231 LM cell lines using cell surface markers (CD24-/CD44+/ESA+). These cells were previously transplanted into the mammary fat pad of nude mice and the results of our limiting dilution analysis indicate that CSCs had a significantly higher ability of forming breast cancer in the injected animals which explains our rationale to use CSCs in our research. In order to exploit this lipogenic pathway for the treatment and chemoprevention of breast cancer, we then examined the effects of resveratrol on breast cancer cells. Resveratrol is a natural polyphenolic compound and has been shown to exhibit cardio-protective as well as anti-neoplastic effects on various types of cancers. However, the exact mechanism of its anti-tumor effect is not clearly defined. We observed that resveratrol significantly reduced the cell viability by inducing apoptosis in parental cells as well as in CSCs. Resveratrol also inhibited mammosphere formation which is an inherent property of CSCs. This inhibitory effect of resveratrol is accompanied by a significant reduction in lipid synthesis which is caused by the down-regulation of the FAS gene followed by up-regulation of pro-apoptotic genes, DAPK2 and BNIP3. The activation of apoptotic pathway in the cancer stem-like cells was suppressed by FAS overexpression suggesting that resveratrol-induced apoptosis is indeed through the modulation of FAS-mediated cell survival signaling. Importantly, resveratrol was able to significantly suppress the growth of CSC in an animal model of human breast cancer xenograft without showing apparental toxicity. Taken together, our results indicate that resveratrol is capable of inducing apoptosis in the CSCs through suppression of lipogenesis by modulating FAS expression, which highlights a novel mechanism of anti-tumor effect of resveratrol. Taken together, our results indicate that resveratrol is capable of inducing apoptosis in the cancer stem-like cells through suppression of lipogenesis by modulating FAS expression, which highlights a novel mechanism of anti-tumor effect of resveratrol. In the second part of research, we tried to determine the role of elevated level of lipogenesis in normal to ductal carcinoma in situ (DCIS) progression. For this, we first analyzed the expression profile of various lipogenic genes using an expression microarray and found that CSCs from DCIS.com showed significantly higher level of ATP-citrate lyase (ACLY), acetyl-CoA carboxylase (ACC) and FAS than the normal non-tumorigenic stem-like cells obtained from MCF10A. The result was also confirmed by qRT-PCR and Western blot as well as in clinical specimens of DCIS by immunohistochemistry. In the next step, we detected that SREBP1, the master regulator of lipogenic genes, is also upregulated in DCIS and further identified that SREBP1 regulates the co-ordinate expression of ACLY, ACC and FAS ultimately resulting in the elevation of lipogenesis. In order to determine the role of SREBP1 overexpression in normal to DCIS transition, we overexpressed the SREBP1 in MCF10A cells which induced a significant increase in the downstream key lipogenic genes ACLY, ACC1 and FAS which resulted in the clear upregulation of total lipid content in the cells. Furthermore, we found that this elevation of lipogenesis in MCF10A-SREBP1 stem-like cells confers proliferative advantage as well as a significant increase in mammosphere forming ability and anchorage independent growth (3D culture). Thus, our results showed a possibility that increased lipogenesis in normal stem-like cells may be responsible for providing oncogenic transformation properties which can be confirmed at least in our in vitro model. We then examined the effects of resveratrol on CSCs sorted from DCIS.com. We found that resveratrol decreased the cell viability and increased apoptosis by reducing the total lipid content by inhibiting the expression of SREBP1 and downstream lipogenic genes. Resveratrol also hindered the stemness of the DCIS CSCs by inhibiting its mammosphere forming ability. When DCIS CSCs were transplanted into mammary fat pad of nude mice which were on resveratrol treatment, we observed that resveratrol significantly suppressed the formation of DCIS by downregulating lipogenic genes and by upregulating pro-apoptotic genes, DAPK2 and BNIP3. Collectively, our results indicate that lipogenic genes SREBP1 co-ordinately regulates the overexpression of ACLY, ACC1 and FAS in DCIS CSCs at an early stage of breast tumorigenesis and thus confer proliferative and survival advantages. Anti-growth effect of resveratrol on DCIS CSCs also provides us with a strong rationale to use this agent for chemo-prevention against DCIS.

The α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs) are ligand-gated glutamatergic ion channels that mediate most excitatory neurotransmission in the brain. Alterations in AMPAR synaptic accumulation mediate synaptic plasticity, including long-term potentiation, long-term depression and homeostatic synaptic plasticity. AMPAR abundance in neurons is determined by balanced processes of protein translation and degradation. Changes in AMPAR function and trafficking have direct impacts on synaptic transmission and cognitive functions. However, the molecular mechanisms regulating AMPAR expression and dynamics in neurons remain largely unknown. In this thesis, two molecular mechanisms that regulate AMPAR translation and protein stability through two different signaling pathways, 5' adenosine monophosphate-activated protein kinase (AMPK) and sirtuin 2 (SIRT2), are described. It is shown that SIRT2, a NAD+-dependent protein deacetylase, directly controls AMPAR stability by regulating AMPAR acetylation. For the first time, we discovered that AMPARs are subject to lysine acetylation, a novel form of post-translational modification for glutamate receptors. Under basal conditions, AMPARs are highly acetylated at their intracellular C termini, which protects against ubiquitination to antagonize AMPAR endocytosis and degradation, leading to prolonged receptor half-life. SIRT2 is also identified as the enzyme responsible for AMPAR deacetylation. Knockdown of SIRT2 led to elevated AMPAR acetylation and reduced ubiquitination, and consequently, increased AMPAR levels and synaptic transmission. SIRT2 knockout mice displayed weakened synaptic plasticity and impaired learning and memory. Resveratrol is a phytoalexin that has been shown to increase AMPAR expression and synaptic accumulation in neurons. The resveratrol effect on AMPAR expression is independent of sirtuin 1, the conventional target of resveratrol, but rather is mediated by AMPK and its downstream phosphoinositide 3-kinase (PI3K)/Akt pathway. Application of the AMPK activator, 5-aminoimidazole-4-carboxamide 1-β-D-ribofuranoside (AICAR), to neurons mimics the effects of resveratrol on both signaling and AMPAR expression. The resveratrol-induced increase in AMPAR expression results from elevated protein synthesis through the AMPK-PI3K pathway activation. These studies describe novel regulatory mechanisms responsible for the control of AMPAR protein amount and subcellular distribution in neurons, providing insights into our understanding of synaptic plasticity, brain function and neurological disorders. / 2017-12-06T00:00:00Z

Autism spectrum disorder (ASD) is classified as a neurovelopmental disorder, presenting impairments in social communication and sociability, as well as stereotyped behavioral patterns. Although the etiology remains unknown, there is growing evidence suggesting a complex interplay between genetic and environmental risk factors during the gestational period. Many alterations are related to ASD, as multisensory alterations and recent data were pointing out the misbalance between excitation and inhibition, with high predominance in excitation compound, in cortical areas related to sensory processing. The valproic acid (VPA) exposure is an environmental risk to ASD and VPA is commonly used by our group to induce autistic-like behaviors in rodents. We previously showed that a prenatal subchronic treatment of the pregnant rats with resveratrol (RSV) prevented the social deficits induced by VPA in male offspring rats. The present work evaluated the influence of RSV and VPA interaction in the nest seeking behavior in 10 days old male rats and in the relative genic expression levels of synaptic proteins (Sinaptophysin) in excitatory (PSD95) and inhibitory synapses (Gephyrin) in amygdala region of 30 days old rats. We identified impairments in the number of correct choices to the nest in VPA group, which were in accordance to the literature data. Nevertheless, we showed, for the first time, that resveratrol were able to prevent these impairments In RSV+VPA group. Besides, the present work showed important significant alterations at the genic expression level of synaptic proteins related to excitatory and inhibitory synapses in the amygdala region, an important brain structure related to attachment behavior and altered in ASD. Therefore, these data highlights resveratrol as an important molecule for prevention of autistic-like sensory behaviors in the animal model of autism induced by prenatal exposure to VPA, as well as an important tool for seeking etiological targets and physiopathology studies in TEA.

O consumo de álcool tem sido considerado um problema de saúde pública. Entretanto, também existem evidências de eventuais benefícios do consumo leve a moderado de algumas bebidas alcoólicas, no que se refere a doenças crônicas não transmissíveis. As doenças periodontais, sendo a sexta doença crônica mais prevalente, também têm sido associadas ao consumo de álcool com resultados controversos. Esta tese avaliou, através de três artigos a relação entre consumo de álcool e doenças periodontais. O primeiro artigo de divulgação, tem por objetivo alertar a profissão a respeito do estado atual do conhecimento em relação a associação entre álcool e doenças periodontais. O segundo artigo é um estudo experimental em modelo animal que avaliou o efeito da dependência química álcool sobre desfechos periodontais. Os resultados não mostraram diferenças estatisticamente significativas na perda óssea alveolar e secreção de TNF-α. O terceiro artigo, também em modelo animal, abordou o consumo do vinho tinto e valeu-se de controles total, álcool a 12%, suco de uva e resveratrol. A análise de ocorrência de periodontite espontânea demonstrou que o vinho tinto tem potencial protetor para a perda óssea alveolar e secreção de TNF- α . Os resultados encontrados nessa tese são instigantes e estão em linha com a literatura que demonstra uma relação do tipo curva J entre álcool e doenças periodontais, na qual até um determinado nível, o fator comporta-se como protetor. Assim, essa relação deve ser considerada na abordagem clínica, sem incentivo ao consumo, mas compreendendo até onde este é tolerável e/ou benéfico no que se refere a doenças periodontais. / Alcohol consumption has been considered a public health problem. Otherwise, there is evidence of eventual benefits of a light to moderate consume of some alcoholic beverage, in relation to non-transmissible chronic disease. The periodontal diseases, being the sixth most prevalent chronic disease, also have been associated to alcohol consumption with controversial results. This thesis evaluated, through three articles the relationship between alcohol consumption and periodontal diseases. The first article has the objective of alerting the professionals about the actual knowledge about the relationship between alcohol and periodontal diseases. The second article is an experimental study in animal model which evaluated the alcohol dependence over periodontal outcomes. The results did not show statistically significant differences in alveolar bone loss and TNF- α secretion. The third article, also in animal model, studied the red wine consumption and used total controls, 12% alcohol, grape juice and resveratrol. The analysis of the occurrence of spontaneous periodontitis demonstrated that red wine has a protector potential for alveolar bone loss and TNF- α secretion. The results found in this thesis are curious and they are in line with the literature that demonstrates a relationship like J-curve between alcohol and periodontal diseases, until some level, the factor behave as protector. So, this relation must be considered in clinical approaches, without encouraging the consumption, but understanding how much is tolerable and/or benefit according to periodontal diseases.

A obesidade é uma doença multifatorial fortemente associada com a síndrome metabólica e com as doenças hepáticas. A distribuição da gordura corporal é um fator relevante, e especificamente o tecido adiposo visceral parece ser o elo entre o aumento de peso, a síndrome metabólica e o acúmulo de gordura hepática. Os adipócitos estão envolvidos na regulação do balanço energético e podem ser modulados por hormônios, citocinas e nutrientes, entre eles o resveratrol. São dois os objetivos principais deste trabalho: (1) identificar os níveis basais de expressão do mRNA de SIRT1, adiponectina, FOXO1, PPARg e PPARb/d em diferentes tecidos adiposos (retroperitoneal, subcutâneo e visceral) de indivíduos obesos grau III com diferentes níveis de esteatose hepática; e (2) identificar a ação do resveratrol sobre a expressão do mRNA dos genes citados em adipócitos isolados do tecido adiposo visceral de indivíduos obesos grau III. Os tecidos adiposos foram obtidos durante cirurgia bariátrica. O RNA total foi extraído usando o reagente TRIzol e o mRNA foi quantificado por PCR em tempo real. Para a análise da expressão basal dos genes, dividimos os pacientes em dois grupos: aqueles com esteatose simples ou moderada e aqueles com esteatose severa associada ou não à fibrose e inflamação. Comparando os dois grupos estudados, os pacientes com esteatose severa apresentaram uma menor expressão do mRNA de SIRT1 (p=0,006), apenas no tecido adiposo visceral. Os níveis de adiponectina, FOXO1, PPARg1-3 e PPARb/d não diferiram estatisticamente entre os dois grupos de pacientes nos três depósitos de gordura corporal. O valor de HOMA-IR foi diferente estatisticamente entre os grupos estudados, sendo maior no grupo de pacientes com diagnóstico de esteatose severa associada ou não a fibrose e necroinflamação (p=0,006). Neste mesmo grupo de pacientes, a expressão de SIRT1 e o valor de HOMA-IR correlacionaram-se positivamente no tecido adiposo visceral (r=0,607; p=0,048). Quanto à modulação por resveratrol, houve aumento significativo nos níveis do mRNA de SIRT1 (p=0,021), adiponectina (p=0,025) e FOXO1 (p=0,001) nos adipócitos isolados do tecido adiposo visceral de obesos grau III. A expressão do mRNA de PPARg1-3 foi modulada negativamente (p=0,003) nas células estudadas. Considerando a expressão do PPARb/d, não houve modulação por resveratrol na concentração, tempo e modelo celular estudados. Analisando a literatura, verificamos que valores diminuídos de SIRT1 já foram associados à progressão da esteatose, em modelos experimentais. Neste trabalho, observamos menor transcrição de SIRT1 no tecido adiposo visceral de obesos com esteatose severa, o que poderia prejudicar a biogênese mitocondrial e a oxidação de ácidos graxos, contribuindo com o aumento de ácidos graxos livres na circulação portal, favorecendo o acúmulo hepático de lipídeos nestes pacientes. Desta forma, sugerimos que o aumento da expressão de SIRT1 no tecido adiposo visceral pode ter efeito protetor contra a evolução da esteatose em obesos grau III. Também constatamos que resveratrol ativa a expressão do mRNA de SIRT1, adiponectina e FOXO1 e diminui a expressão de PPARg1-3. Os resultados indicam que resveratrol pode modular o metabolismo dos adipócitos de obesos grau III, possivelmente favorecendo o metabolismo das células estudadas. / Obesity is a complex disease, strongly associated with metabolic syndrome and hepatic disease. The distribution of body fat is important, and specifically visceral adipose tissue seems to be the link between weight gain, metabolic syndrome and hepatic fat accumulation. Adipocytes are involved in the regulation of energy balance and can be modulated by hormones, cytokines and nutrients as resveratrol. The objectives of this study were: (1) to determine the expression pattern of SIRT1, adiponectin, FOXO1, PPARg1-3 and PPARb/d mRNA in different adipose tissues (retroperitoneal, subcutaneous and visceral) of morbidly obese with different levels of hepatic steatosis; and (2) analyze whether resveratrol could modulate the mRNA expression of the cited genes in isolated visceral adipocytes of morbidly obese. The adipose tissue was obtained by bariatric surgery. Total RNAs were extracted using TRIzol reagent and genes reverse transcripts were determined by quantitative polymerase chain reaction. For analysis of basal genes expression, we divided patients in two groups: those with slight or moderate steatosis and other comprising individuals with severe steatosis associated or not with necroinflammation and fibrosis. When comparing the two groups of patients, we found that the amount of SIRT1 mRNA in the visceral adipose tissue of morbidly obese with severe steatosis was decreased (p=0.006). The levels of adiponectin, FOXO1, PPARg1-3 and PPARb/d did not differ statistically between the two groups of patients in the fat depots studied. We found that HOMA-IR value was significantly higher in severe steatosis patients group (p=0.006). Our results also show that the mRNA expression of SIRT1 and HOMA-IR was positively correlated in the visceral adipose tissue of patients with severe steatosis (r=0.654; p=0.048). Regarding the modulation by resveratrol, there was significant increase in SIRT1 (p=0.021), adiponectina (p=0.025) and FOXO1 (p=0.001) mRNA in isolated visceral adipocytes. The mRNA expression of PPARg1-3 was negatively modulated by resveratrol (p=0.003). Considering PPARb/d, there was not a significantly modulation by resveratrol, in the studied model. Reduced quantities of SIRT1 mRNA have been described in severe steatosis using experimental models. We found lower transcription of SIRT1 expression in the visceral adipose tissue of obese patients with severe steatosis, which may impair mitochondrial biogenesis and fatty acids oxidation, contributing to the increase of free fatty acids in portal circulation, impairing liver function. Thus, we suggest that the increased SIRT1 mRNA expression may have a protective role on steatosis in visceral adipose tissue of morbidly obese individuals. Also, we observed that resveratrol activated the expression of SIRT1, FOXO1 and adiponectin and decreases PPARg1-3, which indicate that resveratrol can control adipocytes metabolism, possibly favoring the metabolism of studied cells.

A espécie redox ativa resveratrol (3,5,4’-trihidroxi-trans-estilbeno), uma fitoalexina encontrada nas uvas e no vinho tinto, apresenta importantes efeitos biológicos como atividade antioxidante, anti-inflamatória, antitumoral e cardioprotetora. O sistema nervoso central (SNC) também é alvo do resveratrol que por sua vez pode atravessar a barreira hematoencefálica e exercer efeito neuroprotetor, modulando importantes funções neurogliais. Fisiologicamente os astrócitos controlam importantes funções cerebrais, principalmente, relacionadas ao metabolismo glutamatérgico, à plasticidade sináptica e neuroproteção; e em situações neuropatológicas, relacionadas ao estresse oxidativo. Assim, neste estudo nós investigamos o efeito do resveratrol sobre importantes parâmetros gliais em células C6 frente a dois modelos de insulto oxidativo: (I) 1 mM de H2O2/0,5 h e (II) 0,1 mM de H2O2/6 h. Avaliamos, nessas condições, o perfil das principais defesas antioxidantes enzimáticas celulares, a genotoxicidade celular e possíveis vias de sinalização que possam contribuir para o melhor entendimento do mecanismo de ação do resveratrol no SNC. Nós demonstramos que o resveratrol modula a captação de glutamato; a atividade da enzima glutamina sintetase; os níveis intra e extracelulares de glutationa; a secreção da proteína S100B; as enzimas SOD, CAT e GPx; a peroxidação lipídica; a frequência de micronúcleos; as enzimas heme oxigenase 1 e iNOS e o fator de transcrição NFκB, de maneira dependente das condições oxidativas do meio e do ambiente redox celular. Dessa forma, nossos resultados mostram que o resveratrol apresenta comportamentos anti e pró-oxidante e que sua ação neuroprotetora pode estar relacionada a modulação da atividade glial e da heme oxigenase 1. Enfim, o resveratrol pode representar um potencial agente terapêutico em patologias que envolvam déficits no sistema glutamatérgico associado ao estresse oxidativo. / The redox active compound, resveratrol (3,5,4 '-trihydroxy-trans-stilbene), a phytoalexin, found in grapes and red wine, has a wide range of biological effects, such as, antioxidant, antiinflammatory, anticancer and cardioprotective. The central nervous system (CNS) is also the target of resveratrol which is able to trespass the blood-brain barrier and exerts neuroprotective effects by modulating important glial parameters. Physiologically, astrocytes control important brain functions, mainly related to glutamatergic metabolism, synaptic plasticity and neuroprotection; and in neurophatology events related to oxidative stress. In this study, we investigated the effect of resveratrol on important parameters in C6 astoglial cells against oxidative insult in two models: (I) 1 mM H2O2/0.5 h and (II) 0.1 mM H2O2/6 h. We evaluated under these conditions, the activity of the major cellular enzymatic antioxidant defenses, the possible genotoxicity and cell signaling pathways that may contribute to better understanding the mechanism of resveratrol in the CNS. Resveratrol modulates glutamate uptake; glutamine synthetase activity; intracellular and extracellular levels of glutathione; S100B secretion; the enzymes SOD, CAT and GPx; lipid peroxidation; the frequency of micronuclei; the enzymes heme oxygenase 1 and iNOS and the transcription factor NFκB depending upon the oxidant conditions of the milieu and the cellular redox environment. Thus, our results show that resveratrol presents anti and pro-oxidant effects and their neuroprotective action may be related to modulation of glial function and heme oxygenase 1. Finally, resveratrol can represent a potential therapeutic agent against pathologies associated to glutamatergic system and oxidative stress.

O transtorno do espectro do autismo (TEA) representa um grupo de desordens do neurodesenvolvimento, caracterizados por 1) déficits na comunicação e na interação social e 2) comportamentos repetitivos e interesses/atividades restritas. A etiologia do TEA reside em uma interação complexa entre fatores genéticos e fatores de risco ambiental. A exposição prénatal ao ácido valproico (VPA) tem sido associada com um aumento significativo no diagnóstico de TEA no período pós-natal e, baseado nessas evidências, um modelo animal de autismo foi proposto. Anormalidades neuroquímicas, morfológicas e comportamentais, similares àquelas encontradas em indivíduos com diagnóstico de TEA, têm sido descritas nesse modelo. Ainda, validades preditivas (respostas análogas para tratamentos), de construto (mesma disfunção biológica que origina certa condição em humanos) e de face (características endofenotípicas similares às encontradas no transtorno estudado) estão presentes nesse modelo, garantindo sua eficácia como um método confiável de pesquisa experimental. Considerando os efeitos neuroprotetores, antioxidantes e anti-inflamatórios do resveratrol (RSV), nós investigamos a influência do tratamento pré-natal com RSV nos comportamentos sociais no modelo animal de autismo induzido por exposição pré-natal ao VPA. A administração pré-natal de RSV preveniu as alterações sociais, induzidas pelo VPA, avaliadas nesse estudo. A interação molecular entre o RSV e o VPA é baixa e altamente instável, sugerindo efeitos celulares ao invés de processos químicos independentes. Por fim, os achados da presente tese originaram: (1) um capítulo de livro descrevendo os achados no modelo animal de autismo por exposição pré-natal ao VPA; (2) um artigo onde uma estratégia experimental promissora, utilizando resveratrol (RSV), foi delineada para avaliar alterações no desenvolvimento relacionadas a alterações neurais e comportamentais no TEA; (3) uma patente para o uso dessa estratégia experimental; (4) resultados preliminares sobre os alvos moleculares do RSV e do VPA envolvendo a etiologia do autismo; e (5) um comentário técnico em um artigo de alto impacto ressaltando o conhecimento e domínio adquirido pelo grupo nos estudos dentro do modelo animal de autismo induzido por exposição pré-natal ao VPA. / Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by 1) deficits in social communication and social interaction and 2) restricted repetitive behaviors, interests, and activities (RRBs). Its etiology involves a complex interplay of both genetic and environmental risk factors. Prenatal exposure to valproic acid (VPA) has been associated with significantly increased risks of ASD and, based on this fact, an animal model of ASD was proposed. Neurochemical, morphological, and behavioral abnormalities, similar to those found in individuals with ASD have been described in this model. Construct (the same biological dysfunction that causes the human disorder), face (strong analogies to the endophenotypes of the human disorder), and predictive (analogous response to treatments) validities are also present in this model, ensuring its effectiveness as a trustworthy research tool. Considering the neuroprotective, antioxidant and anti-inflammatory effects of resveratrol (RSV), we investigated the influence of prenatal RSV treatment on social behaviors of in the animal model of ASD induced by prenatal exposure to VPA. Prenatal administration of RSV prevented the VPA-induced social impairments evaluated in this study. The molecular interaction between RSV and VPA is weak and highly unstable, suggesting cellular effects instead of a single chemical process. In summary, the present thesis findings resulted in: (1) a book chapter describing the findings in the VPA animal model of ASD; (2) an article where a promising experimental strategy is design to evaluate developmental alterations implicated in neural and behavioral impairments in ASD; (3) a patent protecting the use of this research strategy; (4) preliminary results about molecular targets of RSV and VPA involved in the etiology of autism; and (5) a technical comment in a high impact article, showing that we are performing our work in the state of the art.

Transtorno do espectro do autismo (TEA), é um transtorno do neurodesenvolvimento caracterizado por perturbações na comunicação social recíproca e na manifestação de comportamentos, interesses e atividades repetitivos e restritos. Embora a etiologia do autismo ainda seja desconhecida, há fortes evidências de que esta condição é causada por uma complexa interação de fatores genéticos e ambientais durante o desenvolvimento. Além disso, uma das características preponderantes a nível de circuitaria neural é o desequilíbrio entre excitação e inibição, com o predomínio do primeiro. A exposição ao ácido valpróico (VPA) durante a gestação é um dos conhecidos fatores de risco ambiental. Com base nesta informação, o VPA é comumente utilizado para desencadear um fenótipo do tipo autista em murinos. Nosso grupo demonstrou previamente que um tratamento subcrônico com resveratrol (RSV) aplicado a ratas prenhes é capaz de prevenir os prejuízos no comportamento social induzidos na prole pelo VPA. No presente trabalho, nós investigamos a influência do tratamento prenatal com o RSV nos níveis de expressão de proteínas sinápticas excitatórias (PSD-95 e neuroliguina- 1) e inibitórias (gefirina e neuroliguina-2) no córtex pré-frontal medial (CPFm) e no hipocampo de filhotes machos aos 30 dias de vida. O balanço entre excitação e inibição nestas regiões encefálicas já foi associado de maneira causal com a modulação do comportamento social em camundongos. Algumas alterações que observamos no grupo VPA foram contrapostas pela ação do RSV. Em resumo, RSV leva a uma tendência de diminuição da proteína PSD-95 no CPFm nos animais do grupo VPA+RSV em comparação ao grupo VPA (p=0,092), provavelmente exercendo suas ações ao nível da tradução. Adicionalmente, RSV aumenta significativamente os níveis de expressão gênica de gefirina no CPFm e hipocampo. Portanto, nós identificamos dois mecanismos diferentes pelos quais o RSV poderia reduzir a excitabilidade neuronal neste modelo animal de autismo. Isto se soma às crescentes evidências sobre desregulações na razão excitação/inibição no autismo que se relacionam com alterações de comportamento, e pode ser a base da ação preventiva exercida pelo RSV. / Autism spectrum disorder (ASD) is a group of neurodevelopmental disabilities characterized by sociability impairments accompanied by verbal and nonverbal communication deficits and stereotyped behavioral patterns. Although ASD etiology is still not known, there is growing evidence that this disorder is caused by a complex interplay of both genetic and environmental risk factors acting at the developmental stages and that a misbalance between excitation and inhibition (with predominance of the former) is a prominent characteristic at the circuitry level. One of the known risk factors is maternal use of valproic acid (VPA) during gestation. Based on this observation, VPA is commonly used to generate an ASD-like condition in rodents. We previously showed that a prenatal subchronic treatment of the pregnant rats with Resveratrol (RSV) prevented the social deficits generated by VPA in the male offspring. In this work, we aimed to investigate the influence of prenatal RSV treatment on the expression levels of synaptic proteins of excitatory (PSD-95 and neuroligin-1) and inhibitory (gephyrin and neuroligin-2) contacts of medial prefrontal cortex (mPFC) and hippocampus in young male rats. Excitation/inhibition balance in these two brain regions is implicated causally in the modulation of social behaviors in murines. We identified alterations in the VPA animal model of autism, some of which were corrected by the RSV treatment. In summary, we found that RSV leads to a trend of decrease in the level of protein PSD-95 in the mPFC of the VPA+RSV group animals compared to the VPA group (p=0,092), probably exerting its actions at the translation level. In addition, RSV increases gene expression of gephyrin in both mPFC and hippocampus. Therefore, we identified two different mechanisms of reduction of the neuronal excitability mediated by RSV treatment in this animal model of autism. This adds evidence to the growing body of findings about alteration of behaviors mediated by excitation/inhibition regulation in autism, and can be the basis for the phenotypic prevention exerted by RSV.