L’obésité et le diabète sont associés à des complications, notamment une fragilité cutanée. Celle-ci pourrait être associée à une altération du métabolisme du glucose et à une augmentation du tissu adipeux sous-cutané. Il a été montré que l’hypoderme pourrait avoir une fonction spécifique pour la peau. Notre travail a consisté d’une part à caractériser l’adiposité hypodermique et à étudier son influence dans la réactivité du tissu cutané en réponse à des pressions faibles ou fortes chez des souris obèses et d’autre part à étudier le processus de cicatrisation. Les fortes pressions augmentent la fragilité cutanée ce qui peut aboutir à des lésions, notamment des ulcères de pression. Les études ont été réalisées chez des souris C57BL/6J développant une obésité induite par une alimentation riche en lipides et en sucres pendant 4 et 12 semaines. La taille des adipocytes de l’hypoderme a été mesurée ainsi que leur réponse lipolytique en présence ou non d’insuline. La réactivité tissulaire a été évaluée en mesurant les variations du flux sanguin en réponse : 1) à l’application d’une pression locale faible afin de déterminer la vasodilatation induite par la pression (PIV), 2) par iontophorèse d’acétylcholine ou de nitroprussiate de sodium. Afin d’explorer le processus spécifique d’ulcère de pression chez les souris obèses diabétiques, une compression par cycles d’ischémie-reperfusion a été réalisée. Ces études ont été complétées par des explorations métaboliques, histologiques et biochimiques. Par ailleurs nous avons déterminé l’impact de l’augmentation de l’adiposité sur des fibroblastes dermiques in vitro afin de mieux comprendre le processus de cicatrisation.Dans ce travail de thèse, nous avons mis en évidence une augmentation de l’adiposité hypodermique associée à une insulinorésistance tissulaire et systémique. Nous avons également montré un retard de cicatrisation en fonction de l’évolution de l’obésité et des réponses micro vasculaires diminuées post cicatrisation par rapport à une peau non lésée / Obesity and diabetes led to complications, including skin fragility. Skin fragility could be associated to a glucose metabolism alteration and a subcutaneous adipose tissue increase. It has been shown that hypodermis could have a specific function for the skin. Our work consisted on the one hand in characterizing the dermal adiposity and studying its involvement in the skin tissue reactivity in response to low or high pressures in obese mice and, on the other hand, in studying the healing process. High pressures increase cutaneous fragility which can lead to skin wounds, in particular pressure ulcers. This study was realized using C57BL/6J male mice with a diet-induced obesity. C57BL/6J mice were fed a high fat and high sugar diet during 4 or 12 weeks. Hypodermis adipocytes size was measured as well as their lipolytic response in presence or absence of insulin. The skin tissue reactivity was assessed measuring the skin blood flow variations in response to 1) a local pressure application in order to determine the pressure-induced vasodilation (PIV), 2) an acetylcholine or sodium nitroprusside iontophoresis. To examine the specific mechanism of the pressure ulcer in obese diabetic mice, a compression with ischemia-reperfusion cycles was realized. Metabolic assessment, histological and molecular biological studies were carried out to characterize each stage of healing through obesity. Furthermore, we determined the adiposity increase on dermal fibroblasts in vitro to better understand the healing process. In this thesis work, we have highlighted a hypodermis adiposity linked to a tissue and a systemic insulin resistance. We have also showed a delayed healing depending on the evolution of the obesity. The microvascular responses were decreased post healing compared to a non-wounded skin

A dieta hiperlipídica (high-fat, HF) materna durante a gestação e/ou lactação aumenta a susceptibilidade da prole para o desenvolvimento de doenças crônicas na fase adulta. Verificar a hipótese que a ingestão materna de dieta HF nos períodos críticos de desenvolvimento (gestação e/ou lactação) predispõe à doença não alcoólica do fígado gorduroso e alterações pancreáticas e no tecido adiposo de camundongos machos adultos. Camundongos C57BL/6 fêmeas receberam durante a gestação e/ou lactação dieta padrão (standard chow, SC) ou HF. Filhotes machos foram divididos em cinco grupos: SC provenientes de mães SC; G provenientes de mães HF durante a gestação; L provenientes de mães HF durante a lactação; GL/HF provenientes de mães HF durante a gestação/lactação, mantendo a mesma dieta HF no período pós-natal (do desmame aos 3 meses deidade); GL provenientes de mães HF durante a gestação/lactação trocando a dieta para SC no período pós-natal (do desmame aos 3 meses deidade). Foi analisada ao longo do experimento a massa corporal da prole. No sacrifício (3 meses), o fígado, o pâncreas e a gordura epididimária foram removidos, pesados e processados e o sangue foi coletado para análise bioquímica. Ao nascimento e ao desmame, filhotes GL/HF foram mais pesados (+6% e +44%, p<0,05, respectivamente) que os filhotes SC. Os filhotes G apresentaram resistência à insulina e menor expressão do transportador de glicose no fígado (GLUT-2). A esteatose hepática foi observada nos grupos G, L, GL e principalmente nos filhotes do grupo GL/HF. A expressão hepática da proteína ligante de elementos regulatórios de esteróis (SREBP-1c) estava aumentada nos filhotes G, GL e GL/HF. Os filhotes G, GL e GL/HF apresentaram hipertrofia da ilhota pancreática e dos adipócitos quando comparados com o grupo SC. O consumo de dieta HF durante a gestação mostra-se ser o período mais prejudicial para os filhotes adultos de camundongos. A programação metabólica por dieta HF leva ao remodelamento adverso do fígado, do pâncreas e do tecido adiposo / Maternal high-fat diet (HF) during gestation and/or lactation period increases the susceptibility to development of chronic disease in offspring adult life. This work aimed to verify the hypothesis that maternal intake of high-fat diet in critical periods of pregnancy and/or suckling period predisposes to non alcoholic fatty liver disease, pancreatic and adipose tissue alterations in adulthood mice offspring. C57BL/6 female mice were fed, during gestation and/or lactation phases, with standard chow (SC) or HF diet. Male pups were divided into 5 groups: SC- from SC fed dam; G- from HF fed dam during gestation period; L- from HF fed dam during lactation period; GL- from HF fed dam during gestation and lactation periods and GL/HF- from HF fed dam during gestation and lactation, maintaining HF diet from post-weaning to adulthood. We analyzed body mass in all experiment, and at the euthanasia (3 mo-old), liver, pancreas and adipose tissue were removed, weighted and embedded. Blood was collected to biochemical analyses. At birth and at weaning, GL/HF pups were heavier than SC pups (+6% and +44%, p<0.05, respectively). G offspring showed insulin resistance and lower glucose transporter-2 expression (GLUT-2). Hepatic steatosis was present in G, L, GL and mainly in GL/HF offspring. Sterol regulatory element-binding protein-1c (SREBP-1c) expression was higher in G, GL and GL/HF offspring. It is important to mention that pancreatic islet hypertrophy and adipocyte hypertrophy were affected in G, GL and GL/HF offspring in comparison to SC. HF diet administration during gestation period is worse than lactation period. Furthermore, this type of programming by HF predisposes to adverse remodeling in liver, pancreas and adipose tissue in adult mice offspring

O objetivo do trabalho foi investigar se há ritmicidade dos eventos lipolíticos e lipogênicos no TA peri-epididimal e caracterizar se a pinealectomia interfere nesse processo. O sacrifício dos animais, controles e pinealectomizados, foi realizado de quatro em quatro horas. Em relação a lipogênese observaram-se diferenças significativas entre os horários analisados, no entanto, a comparação entre grupos, não mostrou diferenças significativas, indicando que a pinealectomia não interfere nesse processo metabólico do TAB. O estudo da lipólise mostrou que existem algumas diferenças significativas entre os horários, contudo, a pinealectomia também não interferiu no ritmo desse processo. A utilização do programa COSINOR, para análise da existência de ritmos, evidenciou que existe um ritmo, tanto na lipogênese quanto na lipólise, mas que não ocorre de maneira circadiana, ou seja, não ocorre em intervalos de 24h ±4. Também não foram encontradas diferenças significativas, entre os grupos, quando analisadas: consumo alimentar, ingestão hídrica e evolução do peso corporal. / The objective was to investigate whether there rhythmicity of events in lipolytic and lipogenic TA peri-epididymal and characterize whether pinealectomy interferes with this process. The sacrifice of animals, controls and pinealectomized was performed every four hours. In relation to lipogenesis observed significant differences between the times tested, however, the comparison between groups showed no significant differences, indicating that pinealectomy does not intervene in the metabolic process of WAT. The study of lipolysis showed that there are some significant differences between the times, however, pinealectomy did not affect the rhythms of this process. The use of COSINOR program for analysis of the existence of rhythms, suggest that there is a rhythm in both lipogenesis and lipolysis, but that does not occur in a circadian manner, i.e., does not occur at intervals of 24 ± 4. We also found no significant differences between groups when analyzed food intake, water intake and body weight evolution.

Made available in DSpace on 2016-06-02T19:22:09Z (GMT). No. of bitstreams: 1 5256.pdf: 6965922 bytes, checksum: 5df2e41fa93348b8ef396978016ce615 (MD5) Previous issue date: 2013-06-06 / Universidade Federal de Sao Carlos / Visceral obesity is an important risk factor cardiovascular diseases. After menopause, fat distribution shifts to visceral depots leading to lipid metabolism disorders and chronic lowgrade inflammation. Resistance training (RT) has beneficial effects in postmenopausal women, but its effectiveness in normalizing visceral adipose tissue disorders is not well understood. To address this questions adult female Sprague-Dawley rats were randomly divided into six groups (n=6 per group): sham-sedentary (SHAM), ovariectomized- sedentary (OVX), SHAM-trained (S-T), OVX-T. Sham or ovariectomy procedure was performed with 250 grams. Three weeks after the surgery, trained groups started 10 weeks of climbing in a 1.1-m vertical ladder with progressive load of 65%, 85%, 95% and 100% of rat s previous maximal overload. All animals were killed 92 days after being ovariectomized and trained animals were killed 48 hours after the last training session. Mesenteric, parametrial and subcutaneous adipose tissues were prepared for morphometric analyses in colidina and osmium tetroxide and part of mesenteric adipose tissue was stored for mRNA analyses by quantitative PCR. Resistance training prevented ovariectomy-induced higher body weight, food intake, feeding efficiency and mesenteric and subcutaneous, but not parametrial adipocyte area. In addition, RT avoided OVX-induced upregulation in the lipogenic genes PPAR-&#947;, SREBP-1c and its downstream targets SCD-1 and ACC gene expression. Further, RT increases the gene expression of mitochondrial &#946;-oxidation enzyme CPT-1 in OVX rats. RT also prevented the chronic low-grade inflammation in OVX group, demonstrated by the presence of macrophage markers (F4/80 and CD11b), increase in activated Th1 cells (IFN-&#947;) and the proinflammatory cytokines (TNF-&#945;, IL-1&#946; and IL-6). RT additionally created an antiinflammatory (IL-10) environment. The present results reflect a powerful prophylactic effects of resistance training in preventing pathological effects of estrogen deficiency, both at physiological and molecular levels. Therefore, we suggest that this may be an advantageous low cost-effective treatment at post-menopausal phase, since appropriately prescribed. / A obesidade visceral é um importante fator de risco para doenças cardiovasculares. Após a menopausa, as gorduras passam a ser depositadas preferencialmente em locais viscerais e surgem desordens no metabolismo lipídico e um quadro inflamatório crônico de baixa intensidade. O treinamento resistido (TR) possui efeitos benéficos na pós-menopausa, mas não se sabe se ele é efetivo para normalizar as desordens do tecido adiposo visceral. Para pesquisar estas respostas, ratas Sprague-Dawley adultas foram divididas em 4 grupos (n=6 por grupo): Sham sedentárias (SHAM), ovariectomizadas sedentárias (OVX), sham treinadas (SHAM-TR) e OVX-TR. A cirurgia foi realizada quando as ratas estavam com 250 gramas. Após 3 semanas, os grupos treinados iniciaram um programa de treinamento de 10 semanas (3x por semana) de escalada (4-9 repetições) em uma escada vertical de 1,1 m de altura com sobrecargas progressivas de 65%, 85%, 95% and 100% da carga máxima do rato. As ratas foram sacrificadas 92 dias após a ovariectomia e 48 horas após a última sessão de treino. Os tecidos adiposos mesentérico, parametrial e subcutâneo foram preparados em colidina e tetróxido de ósmio para análises morfométricas e parte do tecido mesentérico foi armazenado para análises de expressão gênica por PCR quantitativa. O treinamento resistido evitou o aumento de massa corporal provocado pela ovariectomia, consumo alimentar, eficiência alimentar e a área dos adipócitos mesentérico e subcutâneo, mas não do parametrial. Além disso, evitou a alta expressão dos genes lipogênicos PPAR-&#947;, SREBP-1c e de seus genes alvos ACC e SCD-1. Adicionalmente, o TR, aumentou a expressão do gene da &#946;-oxidação mitocondrial CPT-1 nas ratas OVX-TR. O TR também evitou a condição inflamatória de baixa intensidade instaurada nas ratas OVX, demonstrado pelo acúmulo de macrófagos (F4/80 e CD11b), aumento de células Th1 ativadas (IFN-&#947;) e de mediadores pó-inflamatórios (TNF-&#945;, IL-1&#946; e IL-6), além de criar um ambiente anti-inflamatório (IL-10). Os resultados deste trabalho refletem um significativo efeito profilático do treinamento resistido sobre parâmetros fisiológicos e moleculares na falta dos hormônios ovarianos. Portanto, podemos sugerir que este pode ser um vantajoso tratamento de baixo custo no período pós-menopausal, se adequadamente prescrito.

Made available in DSpace on 2016-06-02T19:22:55Z (GMT). No. of bitstreams: 1 3956.pdf: 1826733 bytes, checksum: e72222f7d290cf5a26f0db7d34928af6 (MD5) Previous issue date: 2011-10-20 / Financiadora de Estudos e Projetos / The purpose of this study was to investigate the effects of high-fat diet and swimming and resistance training in the adipose tissue, endocannabinoid system and lipid profile in obese rats. Wistar adult male rats were divided into 6 groups (n = 10 per group): sedentary chow diet (SP); sedentary high-fat diet (SH); swimming chow diet (NP); swimming high-fat diet (NH); resistance training chow diet (FP); resistance training high-fat diet (FH). After three weeks feeding on a chow diet or high-fat diet, the animals started the exercise protocols. The NP and NH groups swam 60 minutes/day, five days a week, with a constant overload of 5% body weight during 8 weeks in tanks of 50 cm of height and 30 cm of diameter, for 8 weeks. The groups FP and FH started the resistance training with weights tied to their tails, once every three days for 8 weeks. The animals of SP and HS groups remained sedentary and fed their respective diets. After this period all animals were sacrificed by decapitation and tissues dissected, weighed and immediately stored at -80 º C. High-fat diet increased body weight gain, relative weight of adipose tissues (epididymal, retroperitoneal, visceral and subcutaneous) and adipose tissue area (epididymal, retroperitoneal and visceral). It also increased the fat percentage of all adipose tissues and liver, and increased gene expression of CB1 receptor. The trained groups, both resistance training and swimming, presented lower values of adipocyte area, benefits in lipid profile, lower percentage of fat in the adipose tissue and liver, lower body weight gain, and lower values for gene expression the CB1 receptor. Thus our results indicate the potential benefits of the resistance training and swimming as non pharmacological alternatives to control the deleterious effects of high-fat diet on adipose tissue, lipid profile, lipid content of tissues and control of the endocannabinoid system imbalance caused by high-fat diet. / O objetivo do presente estudo foi investigar os efeitos da dieta hiperlipídica e do treinamento de natação e força sobre o tecido adiposo, perfil lipídico e sistema endocanabinóide de ratos obesos. Para isso, utilizamos sessenta ratos adultos machos divididos em seis grupos: Sedentário Padrão (SP); Sedentário Hiperlipídico (SH); Natação Padrão (NP); Natação Hiperlipídica (NH); Força Padrão (FP); Força Hiperlipídica (FH). Após três semanas recebendo dieta padrão ou hiperlipídica, os animais iniciaram os protocolos de exercício. Os grupos NP e NH nadaram 60 minutos por dia, 5 dias na semana com uma carga de 5% do peso corporal atada ao corpo, em tanques de 50 cm de altura e 30 cm de diâmetro, durante 8 semanas. Os grupos FP e FH realizaram exercício de subida em escada com pesos atados às suas caudas, uma vez a cada três dias, durante 8 semanas. Os animais dos grupos SP e SH continuaram sedentários e alimentados com suas respectivas dietas. Após esse período todos os animais foram sacrificados por decapitação, e os tecidos dissecados, pesados e imediatamente congelado a -80ºC. A dieta hiperlipídica aumentou o ganho de massa corporal, peso relativo dos tecidos adiposos (epididimal, retroperitoneal, visceral e subcutâneo) e área de adipócitos (epididimal, retroperitoneal e visceral). Também aumentou o percentual de gordura de todos os tecidos adiposos e fígado, além de aumentar a expressão gênica do receptor CB1. Os grupos treinados, tanto em força quanto em natação, apresentaram menores valores de área de adipócitos, melhora do perfil lipídico, menores valores no percentual de gordura dos tecidos adiposos e fígado, menores ganhos de massa corporal, além de menores valores de expressão gênica para o receptor CB1. Assim nossos resultados indicam os potenciais benefícios do treinamento força e natação, como alternativas não farmacológicas para controlar os efeitos deletérios da dieta hiperlipídica sobre o tecido adiposo, perfil lipídico, conteúdo lipídico dos tecidos e controle do desequilíbrio do sistema endocanabinóide provocado pela dieta hiperlipídica.

(EN) GH/IGF-1 axis components (GH, growth hormone receptor (GH-R), IGF-1, IGF-1 receptor (IGF-1R), IGF-binding proteins (IGFBPs)) participate in the control of glucose metabolism, inflammatory processes as well as cell proliferation and differentiation, including adipocytes and monocytes. The aim of the present study was to evaluate the role of local mRNA expression of GH/IGF-1 axis components in subcutaneous adipose tissue (SCAT) and peripheral monocytes (PM) in the development of insulin resistance and differences of adipose tissue mass in following groups of patients: obese females with and without type 2 diabetes mellitus and subjects with active untreated acromegaly. A total number of 66 subjects were included in the study: obese females without type 2 diabetes mellitus (OB), obese females with type 2 diabetes mellitus (T2DM), acromegalic patients (AC) and healthy lean control subjects (C). T2DM underwent 2 weeks of very-low- calorie diet (VLCD - energy content 2500 kJ/day). According to our results we suggest that decreased mRNA expression of IGF-1, IGF-1R, IGFBP-2 and IGFBP-3 in adipose tissue of T2DM subjects may contribute to changes of fat differentiation capacity and the increased IGF-1R mRNA expression in peripheral monocytes in these patients may play a role in the regulation of...

Title: Acipimox during Short-Term Exercise Exerts A Negative Feedback of Growth Hormone on Ghrelin Secretion in Patients with Bulimia Nervosa and in Healthy Women: The Role of Lipolysis Objective: Eating disorders, such as bulimia nervosa (BN) and anorexia nervosa (AN), are characterized by abnormal eating behavior. The main features of BN are binge-eating and inappropriate compensatory methods to prevent weight gain. The appetite-modulating peptide ghrelin is secreted by the stomach and shows a strong release of growth hormone (GH). A potential GH-ghrelin feedback loop between stomach and the pituitary has been recently reported. Acipimox (Aci), an analogue of nicotinic acid, inhibits lipolysis in adipose tissue (AT) and reduces plasma glycerol and free fatty acids (FFA) levels. Exercise and Aci are stimulators of GH secretion. We suppose that a negative feedback from increased GH levels during exercise may play a role in reducing plasma ghrelin levels. We surmised that altered baseline activity and exercise-induced activation of the sympathetic nervous system (SNS) results in excessive stimulation of lipolysis associated with negative energy balance and may lead to abnormal AT metabolism in patients with BN. Disruption of the gut-brain-AT axis might be involved in the pathogenesis of BN. The...

Hyperglycemia in critically ill patients was considered for many years an adaptive response to stress conditions being present in both patients with and without previous history of diabetes. Hyperglycemia is caused mainly by peripheral insulin resistance induced by the factors acting counteracting insulin signalling at the postreceptor level. Furthermore, hyperglycemia itself can then increase serum levels of pro-inflammatory cytokines such as tumor necrosis factor alpha (TNF-α), interleukin-6 (Il-6) and interleukin-8 (Il- 8) and others. On the contrary, peripheral insulin resistance induced by pro- inflammatory cytokines may further potentiate hyperglycemia. White adipose tissue represents in addition to its energy storage function also a very active endocrine active organ. In addition to regulation of a number of metabolic processes it also significantly modulates the inflammatory response. In critically ill patients, adipose tissue changes its morphology, i.e. the adipocytes are shrinking and adipose tissue is abundantly infiltrated by macrophages. Paradoxically, overweight and obese critically ill patients have lower mortality than underweight, lean and morbidly obese subjects. In our studies, we selected population of the patients undergoing elective major cardiac surgery with extracorporeal...

(AJ) Adipose tissue produces numerous adipokines, pro- and antiinflammatory cytokines and hormones which may influence the development of insulin resistance, type 2 diabetes mellitus and other comorbidities of the metabolic syndrome. The ability of adipose tissue to store lipids and thus protect other organs and tissues from ectopic lipid accumulation and development of insulin resistance (IR) is largely dependent on the adipogenic potential of preadipocytes. The amount and function of these cells may be the key factor in creating "healthy" adipose tissue or on the contrary "unhealthy" adipose tissue eventually leading to metabolic derangements. The regulation of the amount of body fat by converting preadipocytes into mature adipocytes may be crucial in the prevention and treatment of obesity and its comorbidities. One of the reasons for development of insulin resistance can be the inhibition of the differentiation process of preadipocytes into mature adipocytes with consequent ectopic lipid accumulation caused by the secretion of preadipocyte factor - 1 (Pref - 1). Pref - 1 has been discovered recently as a protein produced by preadipocytes but not by mature adipocytes. Pref - 1 is a member of the protein family sharing similarity with epidermal growth factors which regulate the differentiation of...

O tecido adiposo marrom (TAM), caracterizado pela presença da proteína termogênica UCP-1, é conhecido há muitas décadas como um tecido termogênico em mamíferos, porém sua significância clínica em humanos era considerada pequena, com exceção de neonatos, até que o desenvolvimento e uso de métodos de PET-FDG terem demonstrado que humanos adultos também possuem TAM ativo, especialmente após exposição ao frio. Essa descoberta levou a um enorme aumento nas pesquisas sobre o assunto, já que sua ativação, levando a um aumento do gasto energético, poderia, pelo menos na teoria, ser uma possível arma no tratamento da obesidade e diabetes tipo 2 e sua redução ou ausência ser uma causa de ganho de peso. Muitos compostos vêm sendo estudados como possíveis recrutadores e ativdadores desse tecido. A melatonina é um deles, embora nenhum estudo tenha sido feito em humanos. A melatonina, um hormônio pineal sintetizado à noite com um papel crítico na sincronização do ritmo circadiano, é estudado há várias décadas como um regulador chave do metabolismo energético em diversas espécies animais. Ratos pinealectomizados ganham peso e tem distúrbios metabólicos durante sua vida, e a suplementação noturna de melatonina, reverte estas alterações, sem redução da ingesta alimentar. Devido a isso, uma hipótese é que o papel central da melatonina no metabolismo energético inclui sua função no gasto energético, possivelmente relacionado à ativação do TAM. Muitos modelos experimentais, a maioria em animais hibernantes, demonstraram o papel da melatonina no recrutamento do TAM. Nesse estudo, o objetivo é determinar se a suplementação de melatonina para indivíduos e animais de experimentação (ratos Wistar) deficientes de melatonina aumenta sua ativação. Foi encontrado que, em ratos Wistar, animais pinelaectomizados possuem uma capacidade termogênica do TAM reduzida após exposição ao frio comparado com a temperatura ambiente, e a suplementação de melatonina normaliza essa capacidade termogênica. Esse dado sugere um papel da melatonina na resposta máxima de ativação do TAM após um desafio ao frio agudo. Também foi observado um aumento de expressão de UCP-1 (RNA) em animais repostos com melatonina, tanto em controles como em pinealectomizados, e animais pinealectomizados não repostos apresentam uma expressão de UCP-1 menor que um grupo controle. Em humanos, a suplementação de melatonina aumenta o volume e atividade do TAM em quatro indivíduos pinealectomizados (por tumores pineais) com baixo nível de melatonina no basal, analisado por tomografia de emissão de prótons acoplada a ressonância magnética (PET-RM). Embora a análise do TAM em ambos os protocolos tenha sido distinta, seus resultados apontam para a mesma regulação positiva do TAM pela melatonina. A termografia infravermelha (TIV) foi também realizada em humanos, com aumento de atividade de TAM após exposição ao frio, poréma correlação entre as respostas com a TIV e o PET-RM foi moderada e não significativa. Diferenças entre o protocolo frio e limitação da TIV em indivíduos mais obesos podem ter contribuído para esses resultados. Uma relação positiva da suplementação de melatonina nos lípides (principalmente colesterol e triglicérides) também foi encontrada, porém sem impacto na gordura hepática / Brown adipose tissue (BAT), characterized by the presence of the thermogenic protein UCP-1 have long been known as a thermogenic tissue in mammals, however its significance in humans was considered minor, with the exception of newborns, until FDG-PET exams demonstrated that human adults still have active BAT, especially after cold exposure. This prompted to an incredible increase in research on the field, since its activation, leading to increased energy expenditure could, at least theoretically, be a possible tool for the treatment of obesity and type 2 diabetes and its reduction or absence be a cause of weight gain. Many compounds aiming to recruit and activate BAT have been studied. Melatonin has been one of them, although no study has been performed in humans. Melatonin, a pineal hormone synthetized at night with a critical role in the synchronization of circadian rhythms, has long been studied as a key regulator of energy metabolism in many animal species. Pinealectomized rats gain weight and have metabolic disturbances during life, and the circadian supplementation of melatonin, at night, reverts these alterations, without decrease in energy intake. Due to that, it is hypothesized that a main role of melatonin in energy metabolism includes its action on energy expenditure, possibly related to activation of BAT. Many experimental models, mainly in hibernating animals, have shown a role of melatonin on BAT recruitment. In the present study, we ought to determine if the supplementation of melatonin for melatonin deficient subjects and experimental animals (Wistar rats) increases BAT activation. We found, in Wistar rats, that pinealectomized animals have a reduced BAT thermogenic capacity after acute cold exposure compared with ambient temperature, and melatonin supplementation in this animals leads to normalization of BAT thermogenic capacity. This data suggests a role of melatonin in improving the maximal response of BAT after an acute challenge. We also found that melatonin supplementation increases UCP-1 RNA expression both in control and pinealectomized rats, and pinealectomized rats without supplementation have a reduced UCP-1 expression compared with controls. In humans, we found that melatonin supplementation increased BAT volume and activity in four pinealectomized (due to pineal tumors) individuals with low melatonin at baseline, analyzed by Positron Emission Tomography associated with magnetic resonance (PET-MR). Although the analysis of BAT in both studies was different, their results point to the same positive regulation of BAT by melatonin. We also performed infrared termography (IRT) in humans, but the results were not conclusive since although we also found an increase in BAT activity measured in Watts, the correlation between the methods was moderate. The difference may be due to different protocols of cold exposure between methods, probably inadequate in IRT, as well as maybe to a limitation of IRT in more obese individuals. We also found that melatonin supplementation in melatonin deficient humans may have a positive impact on blood lipid concentrations, (mainly total cholesterol and triglycerides) but, at least for the time studied, does not appear to have an impact on liver fat