De nombreuses études indiquent que la prématurité, qui représente 8 % des naissances, estassociée à des indices précoces de dysfonction vasculaire, d’élévation de la pression sanguineet de survenue de diabète de type 2. Les enfants nés prématurément sont plus sujets auxblessures oxydatives de par l’immaturité de leurs défenses antioxydantes et de leur expositionà des situations pro-oxydantes (exposition à l’air ambiant, à un supplément d’oxygène, ou àune exposition aux infections). Cependant, les conséquences à long terme des blessuresoxydatives induites par une exposition à l’oxygène en période périnatale restent méconnues.Le but de ce doctorat a été de mettre en évidence certains mécanismes pouvant relier lesdommages de la prématurité induits par l’oxygène, et le risque à long terme de développer desmaladies cardiovasculaires et métaboliques dans le concept global d’une programmationdéveloppementale de l’hypertension et des pathologies reliées au syndrome métabolique. Des ratons Sprague-Dawley (SD) ont été exposés à 80 % O2 (O2) vs air ambiant (AA) du 3èmeau 10ème jour de vie. Concernant les paramètres cardiovasculaires, nous avons mesuré aucours de la croissance, la pression sanguine à la queue (de la 4ème semaine à la 15ème semaine)et à l’âge adulte : la réactivité vasculaire à l’angiotensine II (AngII) et au carbachol (ex vivo,carotides) avec ou sans le tempol; la production d’oxyde nitrique (NO) en présence ou non Larginineet de L-sépiaptérine (aorte, immunohistochimie) ainsi que l’expression de la nitricoxyde synthase endothéliale (eNOS) (aorte, immunohistochimie et western blot); le stressoxydant vasculaire (aorte, chemiluminescence) par la mesure de la production d’anionssuperoxide en présence ou non des inhibiteurs de la nicotinamide-adenine-dinucleotide-phosphate (NADPH oxydase) et de la nitric oxyde synthase endotheliale (eNOS), l’apocynine,et N-nitro-L-arginine methyl ester (L-NAME) respectivement, ainsi que le stress oxydantcirculant par la mesure des niveaux plasmatiques de malondialdéhyde (MDA, HPLC); ladensité microvasculaire a été évaluée au niveau du muscle tibial antérieur,immunohistochimie); la vitesse d’onde pulsée (VOP) (entre la valve aortique et juste avant labifurcation ilio-fémorale) a été mesurée par ultrason; le nombre de néphrons a été compté pardigestion acide. L’ontogenèse de la plupart de ces mécanismes a été regardée à l’âge de 4semaines.Concernant les paramètres métaboliques, le poids a été mesuré au cours de la croissance. Àl’âge adulte, la composition corporelle et la tolérance au glucose ont été évaluées. À l’âge de 4 semaines, aucune différence n’a été observée dans la pression sanguine, laréactivité vasculaire et le stress oxydant, mais chez les rats O2 vs AA, la densitémicrovasculaire est moindre, et des changements histologiques suggèrent la présence d’unerigidité artérielle augmentée.À l’âge adulte chez les rats O2 vs AA (n = 6-8 /groupe) : i) les pressions sanguines systoliqueset diastoliques sont augmentées; ii) la réactivité vasculaire à l’AngII est augmentée et celle aucarbachol est diminuée, le tempol prévient ces dysfonctions; iii) la production de NO est plusfaible au niveau basal et après stimulation par le carbachol, mais est restaurée après la préincubationavec L-arginine et L-sépiaptérine; iv) l’expression d’eNOS est diminuée parimmunohistochimie et augmentée par western blot; v) les niveaux d’anions superoxide, auniveau basal et en réponse à l’AngII, sont augmentés et sont induits par la NADPH oxydase etle non-couplage d’eNOS; vi) les niveaux plasmatiques de MDA sont augmentés; vii) Ladensité microvasculaire est moindre; viii) la VOP est augmentée; ix) le nombre de néphrons par rein est réduit; x) le poids est plus faible au cours de la croissance et un catch up estobservé à l’âge adulte; la composition corporelle n’est pas différente entre les groupes; xi) latolérance au glucose est diminuée. Ces résultats supportent l’hypothèse d’une programmation développementale des maladiescardiovasculaires et métaboliques à l’âge adulte à la suite d’un stress hyperoxique néonatal. / Many studies showed that prematurity, which represents 8 % of birth, is associated with earlyindices of vascular dysfunction, increased blood pressure and Type 2 diabetes. Prematuritybabies are more susceptible to oxidative injury, consequence of the immaturity of theirantioxidant defences, and exposure to pro-oxidant situations (oxygen supplementation,infection). However, the long-term consequences of oxidative injury induced by oxygenexposure in the neonatal period are unknown.The aim of these PhD studies was to unravel some mechanisms that might underlie thedamage induced by oxygen and the long-term risk of developing vascular and metabolicdiseases in the overall concept of developmental programming of hypertension and metabolicsyndrome-related diseases. Sprague-Dawley pups were kept with their mother in 80 % O2 (O2) or room air (RA) from day3 to 10 of life. Cardiovascular parameters, tail blood pressure was measured between 4 and15 weeks of life. In adulthood : vascular reactivity (ex vivo carotid rings) to angiotensine II(AngII) and carbachol with and without tempol was studied; studies of nitric oxide (NO)production with and without L-arginine and L-sépiaptérine (aorta, immunohistochemistry)and endothelial nitric oxide synthase expression (eNOS; aorta, immunohistochemistry,western blot) were performed; vascular oxidative stress (aorta, using chemiluminescence) bymeasuring superoxide anion production with and without inhibitors of nicotinamide-adeninedinucleotide-phosphate (NADPH oxydase) and nitric oxyde synthase endotheliale (eNOS),apocynin and N-nitro-L-arginine methyl ester (L-NAME) respectively, and circulating oxidative stress by measuring the plasma levels of malondialdéhyde (MDA, HPLC) wereevaluated; microvascular density was assessed on tibialis anterior muscle sections; pulse wavevelocity (PWV) was measured by ultrasound, between aortic valve and ilio-femoralbifurcation; nephrons were counted after hydrochloric acid digestion. The main observationswere also evaluated at 4 weeks of age. Metabolic parameters: body weight has beenmeasured during the growth. In adulthood, body composition, glucose tolerance wereevaluated. A 4 weeks of age, no difference was observed regarding blood pressure, vascular reactivity,and oxidative stress indices, but in rats O2 vs. RA (n = 6-8 /group), microvascular rarefactionand histological changes suggesting enhanced vascular stiffness were present.To adulthood, rats O2 vs. RA (n = 6-8/group) : i) systolic and diastolic blood pressures areincreased; ii) vascular reactivity to Ang II is increased and to carbachol is decreased, thesedysfunction were totally abolished by co-incubation of the vessel rings with tempol; iii) NOproductionis decreased in basal condition and after carbachol stimulation, but is restored afterpre-incubation of aorta sections with L- arginine and L-sépiaptérine; iv) eNOS expression isdecreased by immunohistochemistry but increased by western blot; v) vascular superoxideanion levels are increased in basal condition, after AngII stimulation and this is mediated byNADPH oxydase and eNOS uncoupling; vi) the plasma levels of MDA are increased; vii)microvascular density is decreased; viii) PWV is increased; ix) nephron count per kidney isdecreased; x) body weight is less during growth, but a catch up is observed in adulthood,body composition is similar; xi) the glucose tolerance is decreased in adults. These results support the hypothesis of developmental programming of vascular andmetabolic diseases in adulthood, after exposure to hyperoxic stress in the neonatal period.

Thèse réalisée dans le cadre d'une cotutelle entre l'Université de Montréal et l'Université d'Auvergne en France / Introduction De nombreuses études indiquent que la prématurité, qui représente 8 % des naissances, est associée à des indices précoces de dysfonction vasculaire, d’élévation de la pression sanguine et de survenue de diabète de type 2. Les enfants nés prématurément sont plus sujets aux blessures oxydatives de par l’immaturité de leurs défenses antioxydantes et de leur exposition à des situations pro-oxydantes (exposition à l’air ambiant, à un supplément d’oxygène, ou à une exposition aux infections). Cependant, les conséquences à long terme des blessures oxydatives induites par une exposition à l’oxygène en période périnatale restent méconnues. Le but de ce doctorat a été de mettre en évidence certains mécanismes pouvant relier les dommages de la prématurité induits par l’oxygène, et le risque à long terme de développer des maladies cardiovasculaires et métaboliques dans le concept global d’une programmation développementale de l’hypertension et des pathologies reliées au syndrome métabolique. Matériels et méthodes Des ratons Sprague-Dawley (SD) ont été exposés à 80 % O2 (O2) vs air ambiant (AA) du 3ème au 10ème jour de vie. Concernant les paramètres cardiovasculaires, nous avons mesuré au cours de la croissance, la pression sanguine à la queue (de la 4ème semaine à la 15ème semaine) et à l’âge adulte : la réactivité vasculaire à l’angiotensine II (AngII) et au carbachol (ex vivo, carotides) avec ou sans le tempol; la production d’oxyde nitrique (NO) en présence ou non L-arginine et de L-sépiaptérine (aorte, immunohistochimie) ainsi que l’expression de la nitric oxyde synthase endothéliale (eNOS) (aorte, immunohistochimie et western blot); le stress oxydant vasculaire (aorte, chemiluminescence) par la mesure de la production d’anions superoxide en présence ou non des inhibiteurs de la nicotinamide-adenine-dinucleotide-phosphate (NADPH oxydase) et de la nitric oxyde synthase endotheliale (eNOS), l’apocynine, et N-nitro-L-arginine methyl ester (L-NAME) respectivement, ainsi que le stress oxydant circulant par la mesure des niveaux plasmatiques de malondialdéhyde (MDA, HPLC); la densité microvasculaire a été évaluée au niveau du muscle tibial antérieur, immunohistochimie); la vitesse d’onde pulsée (VOP) (entre la valve aortique et juste avant la bifurcation ilio-fémorale) a été mesurée par ultrason; le nombre de néphrons a été compté par digestion acide. L’ontogenèse de la plupart de ces mécanismes a été regardée à l’âge de 4 semaines. Concernant les paramètres métaboliques, le poids a été mesuré au cours de la croissance. À l’âge adulte, la composition corporelle et la tolérance au glucose ont été évaluées. Résultats À l’âge de 4 semaines, aucune différence n’a été observée dans la pression sanguine, la réactivité vasculaire et le stress oxydant, mais chez les rats O2 vs AA, la densité microvasculaire est moindre, et des changements histologiques suggèrent la présence d’une rigidité artérielle augmentée. À l’âge adulte chez les rats O2 vs AA (n = 6-8 /groupe) : i) les pressions sanguines systoliques et diastoliques sont augmentées; ii) la réactivité vasculaire à l’AngII est augmentée et celle au carbachol est diminuée, le tempol prévient ces dysfonctions; iii) la production de NO est plus faible au niveau basal et après stimulation par le carbachol, mais est restaurée après la pré-incubation avec L-arginine et L-sépiaptérine; iv) l’expression d’eNOS est diminuée par immunohistochimie et augmentée par western blot; v) les niveaux d’anions superoxide, au niveau basal et en réponse à l’AngII, sont augmentés et sont induits par la NADPH oxydase et le non-couplage d’eNOS; vi) les niveaux plasmatiques de MDA sont augmentés; vii) La densité microvasculaire est moindre; viii) la VOP est augmentée; ix) le nombre de néphrons par rein est réduit; x) le poids est plus faible au cours de la croissance et un catch up est observé à l’âge adulte; la composition corporelle n’est pas différente entre les groupes; xi) la tolérance au glucose est diminuée. Conclusion Ces résultats supportent l’hypothèse d’une programmation développementale des maladies cardiovasculaires et métaboliques à l’âge adulte à la suite d’un stress hyperoxique néonatal. / Introduction Many studies showed that prematurity, which represents 8 % of birth, is associated with early indices of vascular dysfunction, increased blood pressure and Type 2 diabetes. Prematurity babies are more susceptible to oxidative injury, consequence of the immaturity of their antioxidant defences, and exposure to pro-oxidant situations (oxygen supplementation, infection). However, the long-term consequences of oxidative injury induced by oxygen exposure in the neonatal period are unknown. The aim of these PhD studies was to unravel some mechanisms that might underlie the damage induced by oxygen and the long-term risk of developing vascular and metabolic diseases in the overall concept of developmental programming of hypertension and metabolic syndrome-related diseases. Materials and methods Sprague-Dawley pups were kept with their mother in 80 % O2 (O2) or room air (RA) from day 3 to 10 of life. Cardiovascular parameters, tail blood pressure was measured between 4 and 15 weeks of life. In adulthood : vascular reactivity (ex vivo carotid rings) to angiotensine II (AngII) and carbachol with and without tempol was studied; studies of nitric oxide (NO) production with and without L-arginine and L-sépiaptérine (aorta, immunohistochemistry) and endothelial nitric oxide synthase expression (eNOS; aorta, immunohistochemistry, western blot) were performed; vascular oxidative stress (aorta, using chemiluminescence) by measuring superoxide anion production with and without inhibitors of nicotinamide-adenine-dinucleotide-phosphate (NADPH oxydase) and nitric oxyde synthase endotheliale (eNOS), apocynin and N-nitro-L-arginine methyl ester (L-NAME) respectively, and circulating oxidative stress by measuring the plasma levels of malondialdéhyde (MDA, HPLC) were evaluated; microvascular density was assessed on tibialis anterior muscle sections; pulse wave velocity (PWV) was measured by ultrasound, between aortic valve and ilio-femoral bifurcation; nephrons were counted after hydrochloric acid digestion. The main observations were also evaluated at 4 weeks of age. Metabolic parameters: body weight has been measured during the growth. In adulthood, body composition, glucose tolerance were evaluated. Results A 4 weeks of age, no difference was observed regarding blood pressure, vascular reactivity, and oxidative stress indices, but in rats O2 vs. RA (n = 6-8 /group), microvascular rarefaction and histological changes suggesting enhanced vascular stiffness were present. To adulthood, rats O2 vs. RA (n = 6-8/group) : i) systolic and diastolic blood pressures are increased; ii) vascular reactivity to Ang II is increased and to carbachol is decreased, these dysfunction were totally abolished by co-incubation of the vessel rings with tempol; iii) NO-production is decreased in basal condition and after carbachol stimulation, but is restored after pre-incubation of aorta sections with L- arginine and L-sépiaptérine; iv) eNOS expression is decreased by immunohistochemistry but increased by western blot; v) vascular superoxide anion levels are increased in basal condition, after AngII stimulation and this is mediated by NADPH oxydase and eNOS uncoupling; vi) the plasma levels of MDA are increased; vii) microvascular density is decreased; viii) PWV is increased; ix) nephron count per kidney is decreased; x) body weight is less during growth, but a catch up is observed in adulthood, body composition is similar; xi) the glucose tolerance is decreased in adults. Conclusion These results support the hypothesis of developmental programming of vascular and metabolic diseases in adulthood, after exposure to hyperoxic stress in the neonatal period.

L’insuline et la sérotonine (5-HT) sont deux acteurs majeurs du maintien de l’homéostasie énergétique, fonction placée sous le contrôle de l’hypothalamus. En ciblant cette région, l’insuline remplit de nombreuses fonctions métaboliques via l’activation de la voie PI3K/Akt. La 5-HT exercent des effets biologiques similaires mais les voies de signalisation impliquées dans ces processus étaient jusqu’alors mal connues. De plus, il avait été démontré que la 5-HT est capable d’activer la voie PI3K/Akt/GSK3β dans l’hippocampe, mécanisme sous-tendant potentiellement les effets antidépresseurs du neurotransmetteur. Les principaux objectifs de cette thèse étaient d’étudier 1/ l’activation de la voie PI3K/Akt par la 5-HT dans l’hypothalamus de rats diabétiques (modèle Goto-Kakizaki) et chercher un potentiel dialogue avec l’insuline and 2/ les mécanismes sous-tendant l’induction de la dépression par une alimentation hyperlipidique, par l’analyse de la phosphorylation d’Akt et GSK3β sous l’action de l’insuline, de la leptine et de la 5-HT dans l’hippocampe de rat.Ici on montre que 1/ la 5-HT stimule la voie PI3K/Akt dans l’hypothalamus et que la phosphorylation d’Akt induite par la 5-HT est atténuée dans des conditions d’insulino-résistance, suggérant l’existence d’un dialogue entre les voies de signalisation de l’insuline et de la 5-HT. Par ailleurs, nos résultats indiquent qu’une alimentation hyperlipidique induit un comportement dépressif réversible chez le rat, qui pourrait impliquer la voie PI3K/Akt/GSK3β dans les neurones subgranulaires du gyrus denté. La mise en évidence d’un dialogue entre les voies de signalisation de la 5-HT, de la leptine et de l’insuline au niveau central enrichit nos connaissances sur le rôle de ces facteurs dans la régulation de l’homéostasie énergétique et de l’humeur, et propose un lien moléculaire entre diabète de type 2, obésité et dépression / Insulin and serotonin (5-HT) are two key players in the maintenance of energy homeostasis which is controlled by the hypothalamus. In this brain region, insulin mediates numerous metabolic effects via the activation of the PI3K/Akt signaling pathway. 5-HT exerts similar biological properties by acting in the hypothalamus but the signaling pathways accountable for these effects are still unclear. Moreover, it has been reported that 5-HT induces the activation of the PI3K/Akt pathway in the hippocampus and the inhibition of GSK3β, suggesting this action as a potential mechanism for the antidepressant effects of this neurotransmitter.The main objectives of this thesis were to study 1/ the serotonin-induced activation of the PI3K/Akt in the hypothalamus of wild type and diabetic rats (Goto-Kakizaki model) and search a potential cross-talk with insulin and, 2/ the mechanisms underlying the high-fat diet induced depression by investigating the role of the phosphorylation of Akt and GSK3β by 5-HT, insulin and leptin in the hippocampus of rats.Here, we show that 5-HT triggers the PI3K/Akt signaling pathway in the rat hypothalamus, and that this activation is attenuated in insulin-resistant conditions, suggesting a cross-talk between insulin and 5-HT. Moreover, we reported that high-fat diet feeding induces a reversible depressive-like behavior, which may involve the PI3K/Akt/GSK3β pathway in subgranular neurons of the dentate gyrus. In conclusion, the activation of the PI3K/Akt pathway and its target GSK3β by 5-HT in the hypothalamus and in the dentate gyrus, respectively, can be impaired in insulin-/leptin-resistant states, which may underlie a link between metabolic diseases and depression.

O Diâmetro Abdominal Sagital (DAS) é uma medida antropométrica relacionada com a gordura visceral e empregada para avaliar a obesidade abdominal, uma variável associada à síndrome metabólica. Sua utilização é indicada na prática clínica para avaliação de risco cardiometabólico em adolescentes obesos. OBJETIVO: Verificar a concordância entre o DAS e a circunferência abdominal (CA) na avaliação da obesidade central e sua associação com os critérios da Síndrome Metabólica e HOMA-IR em adolescentes obesos. CASUÍSTICA E MÉTODOS: Estudo de corte transversal constituído por 83 adolescentes obesos entre 14 e 18 anos, (46 do sexo feminino e 37 do sexo masculino) matriculados no Instituto da Criança do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, nos ambulatórios das Unidades de Endocrinologia Pediátrica e de Adolescentes. Foram submetidos a avaliações antropométricas (IMC, Escore Z do IMC, percentual de gordura corporal, circunferência abdominal, diâmetro abdominal sagital), laboratoriais (HDL-c, triglicérides (TG), glicemia (GLIS) e insulina para o cálculo do HOMA-IR) e de pressão arterial sistólica (PAS) e diastólica (PAD), utilizadas para classificação dos critérios da SM. RESULTADOS: Todos os adolescentes apresentaram valores elevados de IMC (36,9±6,7 kg/m2), Z-IMC (+3,27±0,94) e 91,6% da casuística tiveram valores alterados no percentual de gordura corporal (41,4% para o grupo feminino e 36% para o grupo masculino), confirmando a obesidade grave do grupo. Considerando o percentil >=90 do Center for Disease Control and Prevention (CDC), no National Health and Nutrition Examination Survey (NHANES 2011-2014), 85,5% dos adolescentes apresentaram valores elevados de CA (117,7 ± 14,7) e 89,2% valores alterados no DAS (26,9±3,7). Quanto às variáveis laboratoriais, 32,5% dos pacientes apresentaram diminuição de HDL-c e níveis aumentados de: TG (10,8%); GLIS (3,6%); PAS (32,5%,); PAD (21,7%) e HOMA-IR (79,5%), considerando toda a amostra. De acordo com os critérios utilizados pelo International Diabetes Federation, 27,7% da casuística apresentou SM. O DAS demonstrou estar significantemente correlacionado com as variáveis PAS (r=0,489 p < 0,001), PAD(r=0,277 p 0,011) e HOMA-IR (r=0,462 p < 0,001) nos grupos geral, feminino, masculino, com e sem SM. A correlação encontrada entre as medidas do DAS e CA no grupo geral e feminino foi de r = 0,91 (p 0,000) e, no grupo masculino, de r = 0,93 (p 0,000). A concordância entre a CA e o DAS é significante (Kappa k = 0.511; p < 0,001). Nos grupos geral, feminino e masculino com SM, a concordância é mais expressiva (Kappa k = 1,00; p < 0,001.). Esses resultados mostram que os adolescentes apresentavam risco cardiometabólico aumentado e expressiva obesidade central, identificada pelo DAS e CA, apesar de 73,5% deles estarem medicados. O DAS oferece vantagem metodológica na sua mensuração. CONCLUSÕES: Nas condições deste estudo, conclui-se que: as medidas antropométricas CA e DAS se equivalem para o grupo de adolescentes avaliados na classificação da SM; O DAS é preditor de PAS, PAD e HOMA-IR e forte indicador de risco cardiometabólico em adolescentes obesos / The sagittal abdominal diameter (SAD) is an anthropometric measure related to visceral fat and used to evaluate abdominal obesity, a variable associated with the metabolic syndrome. Studies have suggested its employment in the clinical practice for estimating cardiometabolic risk of obese adolescents. OBJECTIVE: To verify the concordance between SAD and abdominal circumference in the assessment of central obesity and its association with the Metabolic Syndrome cluster and with HOMA-IR in obese adolescents. CASUISTICS AND METHODS: In a cross-sectional study, 83 obese adolescents between 14 and 18 years (46 females and 37males) with body mass index (BMI) of 36.9 ± 6.7 kg/m2, followed at the Pediatric Endocrinology Unit and at the Adolescent Unit of the Children\'s Institute, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo were submitted to anthropometric (BMI, BMI Z Score, body fat percentage, abdominal circumference, sagittal abdominal diameter), laboratory (HDL-c, triglycerides, glycemia and insulin for calculating HOMA-IR) and systolic and diastolic blood pressure assessments aimed for classification of metabolic syndrome. Previous consentment was given by all patients and their families. RESULTS: All adolescents presented elevated BMI and Z-BMI, and high body fat percentage was displayed by 91.6% of the patients (41.4% for the female group and 36% for the male group), confirming severe obesity. Considering the >= 90 percentile cut-off values as provided by the Anthropometric Reference Data for Children and Adults: United States 2011-2014 for abdominal circumference and SAD, 85.5% of the patients presented high abdominal circumference values (117.7±14.7) and 89.2% presented elevated values of SAD (26.9±3.7). With regard to laboratory variables, 32.5% of the patients displayed decreased HDL-c and increased values of: triglycerides (10.8%); glycemia (3.6%); systolic blood pressure (32.5%); diastolic blood pressure (21.7%) and HOMA-IR (79.5%). According to the criteria of the International Diabetes Federation (IDF), 27.7% of patients presented metabolic syndrome. SAD was significantly correlated with systolic (r=0.489 p < 0.001) and diastolic (r=0.277 p 0.011) blood pressures and HOMA-IR (r=0.462 p < 0.001) in the general, female and male groups, with and without metabolic syndrome. The correlation between SAD and abdominal circumference in the general and female groups was r = 0.91(p 0.000) and in the male group was r = 0.93 (p 0.000). The concordance between SAD and abdominal circumference was significant (Kappa coefficient k = 0.511; p < 0.001). In the general, male and female groups with metabolic syndrome, the concordance was more expressive (Kappa coefficient; k = 1.00 and p < 0.001). These results show that the adolescents presented increased cardiometabolic risk and significant central obesity identified by SAD and abdominal circumference although 73.5% of the studied patients were maintained under medication for clinical metabolic syndrome symptoms. SAD displayed methodological advantages concerning its measurement. CONCLUSIONS: Under the conditions of this study, it is concluded that: the anthropometric measurements of SAD and abdominal circumference are equivalent for metabolic syndrome classification of the studied adolescents; that SAD is a predictor of systolic and diastolic blood pressures and HOMA-IR and is a strong indicator of cardiometabolic risk in obese adolescents

O Diâmetro Abdominal Sagital (DAS) é uma medida antropométrica relacionada com a gordura visceral e empregada para avaliar a obesidade abdominal, uma variável associada à síndrome metabólica. Sua utilização é indicada na prática clínica para avaliação de risco cardiometabólico em adolescentes obesos. OBJETIVO: Verificar a concordância entre o DAS e a circunferência abdominal (CA) na avaliação da obesidade central e sua associação com os critérios da Síndrome Metabólica e HOMA-IR em adolescentes obesos. CASUÍSTICA E MÉTODOS: Estudo de corte transversal constituído por 83 adolescentes obesos entre 14 e 18 anos, (46 do sexo feminino e 37 do sexo masculino) matriculados no Instituto da Criança do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, nos ambulatórios das Unidades de Endocrinologia Pediátrica e de Adolescentes. Foram submetidos a avaliações antropométricas (IMC, Escore Z do IMC, percentual de gordura corporal, circunferência abdominal, diâmetro abdominal sagital), laboratoriais (HDL-c, triglicérides (TG), glicemia (GLIS) e insulina para o cálculo do HOMA-IR) e de pressão arterial sistólica (PAS) e diastólica (PAD), utilizadas para classificação dos critérios da SM. RESULTADOS: Todos os adolescentes apresentaram valores elevados de IMC (36,9±6,7 kg/m2), Z-IMC (+3,27±0,94) e 91,6% da casuística tiveram valores alterados no percentual de gordura corporal (41,4% para o grupo feminino e 36% para o grupo masculino), confirmando a obesidade grave do grupo. Considerando o percentil >=90 do Center for Disease Control and Prevention (CDC), no National Health and Nutrition Examination Survey (NHANES 2011-2014), 85,5% dos adolescentes apresentaram valores elevados de CA (117,7 ± 14,7) e 89,2% valores alterados no DAS (26,9±3,7). Quanto às variáveis laboratoriais, 32,5% dos pacientes apresentaram diminuição de HDL-c e níveis aumentados de: TG (10,8%); GLIS (3,6%); PAS (32,5%,); PAD (21,7%) e HOMA-IR (79,5%), considerando toda a amostra. De acordo com os critérios utilizados pelo International Diabetes Federation, 27,7% da casuística apresentou SM. O DAS demonstrou estar significantemente correlacionado com as variáveis PAS (r=0,489 p < 0,001), PAD(r=0,277 p 0,011) e HOMA-IR (r=0,462 p < 0,001) nos grupos geral, feminino, masculino, com e sem SM. A correlação encontrada entre as medidas do DAS e CA no grupo geral e feminino foi de r = 0,91 (p 0,000) e, no grupo masculino, de r = 0,93 (p 0,000). A concordância entre a CA e o DAS é significante (Kappa k = 0.511; p < 0,001). Nos grupos geral, feminino e masculino com SM, a concordância é mais expressiva (Kappa k = 1,00; p < 0,001.). Esses resultados mostram que os adolescentes apresentavam risco cardiometabólico aumentado e expressiva obesidade central, identificada pelo DAS e CA, apesar de 73,5% deles estarem medicados. O DAS oferece vantagem metodológica na sua mensuração. CONCLUSÕES: Nas condições deste estudo, conclui-se que: as medidas antropométricas CA e DAS se equivalem para o grupo de adolescentes avaliados na classificação da SM; O DAS é preditor de PAS, PAD e HOMA-IR e forte indicador de risco cardiometabólico em adolescentes obesos / The sagittal abdominal diameter (SAD) is an anthropometric measure related to visceral fat and used to evaluate abdominal obesity, a variable associated with the metabolic syndrome. Studies have suggested its employment in the clinical practice for estimating cardiometabolic risk of obese adolescents. OBJECTIVE: To verify the concordance between SAD and abdominal circumference in the assessment of central obesity and its association with the Metabolic Syndrome cluster and with HOMA-IR in obese adolescents. CASUISTICS AND METHODS: In a cross-sectional study, 83 obese adolescents between 14 and 18 years (46 females and 37males) with body mass index (BMI) of 36.9 ± 6.7 kg/m2, followed at the Pediatric Endocrinology Unit and at the Adolescent Unit of the Children\'s Institute, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo were submitted to anthropometric (BMI, BMI Z Score, body fat percentage, abdominal circumference, sagittal abdominal diameter), laboratory (HDL-c, triglycerides, glycemia and insulin for calculating HOMA-IR) and systolic and diastolic blood pressure assessments aimed for classification of metabolic syndrome. Previous consentment was given by all patients and their families. RESULTS: All adolescents presented elevated BMI and Z-BMI, and high body fat percentage was displayed by 91.6% of the patients (41.4% for the female group and 36% for the male group), confirming severe obesity. Considering the >= 90 percentile cut-off values as provided by the Anthropometric Reference Data for Children and Adults: United States 2011-2014 for abdominal circumference and SAD, 85.5% of the patients presented high abdominal circumference values (117.7±14.7) and 89.2% presented elevated values of SAD (26.9±3.7). With regard to laboratory variables, 32.5% of the patients displayed decreased HDL-c and increased values of: triglycerides (10.8%); glycemia (3.6%); systolic blood pressure (32.5%); diastolic blood pressure (21.7%) and HOMA-IR (79.5%). According to the criteria of the International Diabetes Federation (IDF), 27.7% of patients presented metabolic syndrome. SAD was significantly correlated with systolic (r=0.489 p < 0.001) and diastolic (r=0.277 p 0.011) blood pressures and HOMA-IR (r=0.462 p < 0.001) in the general, female and male groups, with and without metabolic syndrome. The correlation between SAD and abdominal circumference in the general and female groups was r = 0.91(p 0.000) and in the male group was r = 0.93 (p 0.000). The concordance between SAD and abdominal circumference was significant (Kappa coefficient k = 0.511; p < 0.001). In the general, male and female groups with metabolic syndrome, the concordance was more expressive (Kappa coefficient; k = 1.00 and p < 0.001). These results show that the adolescents presented increased cardiometabolic risk and significant central obesity identified by SAD and abdominal circumference although 73.5% of the studied patients were maintained under medication for clinical metabolic syndrome symptoms. SAD displayed methodological advantages concerning its measurement. CONCLUSIONS: Under the conditions of this study, it is concluded that: the anthropometric measurements of SAD and abdominal circumference are equivalent for metabolic syndrome classification of the studied adolescents; that SAD is a predictor of systolic and diastolic blood pressures and HOMA-IR and is a strong indicator of cardiometabolic risk in obese adolescents

Introduction De nombreuses études indiquent que la prématurité, qui représente 8 % des naissances, est associée à des indices précoces de dysfonction vasculaire, d’élévation de la pression sanguine et de survenue de diabète de type 2. Les enfants nés prématurément sont plus sujets aux blessures oxydatives de par l’immaturité de leurs défenses antioxydantes et de leur exposition à des situations pro-oxydantes (exposition à l’air ambiant, à un supplément d’oxygène, ou à une exposition aux infections). Cependant, les conséquences à long terme des blessures oxydatives induites par une exposition à l’oxygène en période périnatale restent méconnues. Le but de ce doctorat a été de mettre en évidence certains mécanismes pouvant relier les dommages de la prématurité induits par l’oxygène, et le risque à long terme de développer des maladies cardiovasculaires et métaboliques dans le concept global d’une programmation développementale de l’hypertension et des pathologies reliées au syndrome métabolique. Matériels et méthodes Des ratons Sprague-Dawley (SD) ont été exposés à 80 % O2 (O2) vs air ambiant (AA) du 3ème au 10ème jour de vie. Concernant les paramètres cardiovasculaires, nous avons mesuré au cours de la croissance, la pression sanguine à la queue (de la 4ème semaine à la 15ème semaine) et à l’âge adulte : la réactivité vasculaire à l’angiotensine II (AngII) et au carbachol (ex vivo, carotides) avec ou sans le tempol; la production d’oxyde nitrique (NO) en présence ou non L-arginine et de L-sépiaptérine (aorte, immunohistochimie) ainsi que l’expression de la nitric oxyde synthase endothéliale (eNOS) (aorte, immunohistochimie et western blot); le stress oxydant vasculaire (aorte, chemiluminescence) par la mesure de la production d’anions superoxide en présence ou non des inhibiteurs de la nicotinamide-adenine-dinucleotide-phosphate (NADPH oxydase) et de la nitric oxyde synthase endotheliale (eNOS), l’apocynine, et N-nitro-L-arginine methyl ester (L-NAME) respectivement, ainsi que le stress oxydant circulant par la mesure des niveaux plasmatiques de malondialdéhyde (MDA, HPLC); la densité microvasculaire a été évaluée au niveau du muscle tibial antérieur, immunohistochimie); la vitesse d’onde pulsée (VOP) (entre la valve aortique et juste avant la bifurcation ilio-fémorale) a été mesurée par ultrason; le nombre de néphrons a été compté par digestion acide. L’ontogenèse de la plupart de ces mécanismes a été regardée à l’âge de 4 semaines. Concernant les paramètres métaboliques, le poids a été mesuré au cours de la croissance. À l’âge adulte, la composition corporelle et la tolérance au glucose ont été évaluées. Résultats À l’âge de 4 semaines, aucune différence n’a été observée dans la pression sanguine, la réactivité vasculaire et le stress oxydant, mais chez les rats O2 vs AA, la densité microvasculaire est moindre, et des changements histologiques suggèrent la présence d’une rigidité artérielle augmentée. À l’âge adulte chez les rats O2 vs AA (n = 6-8 /groupe) : i) les pressions sanguines systoliques et diastoliques sont augmentées; ii) la réactivité vasculaire à l’AngII est augmentée et celle au carbachol est diminuée, le tempol prévient ces dysfonctions; iii) la production de NO est plus faible au niveau basal et après stimulation par le carbachol, mais est restaurée après la pré-incubation avec L-arginine et L-sépiaptérine; iv) l’expression d’eNOS est diminuée par immunohistochimie et augmentée par western blot; v) les niveaux d’anions superoxide, au niveau basal et en réponse à l’AngII, sont augmentés et sont induits par la NADPH oxydase et le non-couplage d’eNOS; vi) les niveaux plasmatiques de MDA sont augmentés; vii) La densité microvasculaire est moindre; viii) la VOP est augmentée; ix) le nombre de néphrons par rein est réduit; x) le poids est plus faible au cours de la croissance et un catch up est observé à l’âge adulte; la composition corporelle n’est pas différente entre les groupes; xi) la tolérance au glucose est diminuée. Conclusion Ces résultats supportent l’hypothèse d’une programmation développementale des maladies cardiovasculaires et métaboliques à l’âge adulte à la suite d’un stress hyperoxique néonatal. / Introduction Many studies showed that prematurity, which represents 8 % of birth, is associated with early indices of vascular dysfunction, increased blood pressure and Type 2 diabetes. Prematurity babies are more susceptible to oxidative injury, consequence of the immaturity of their antioxidant defences, and exposure to pro-oxidant situations (oxygen supplementation, infection). However, the long-term consequences of oxidative injury induced by oxygen exposure in the neonatal period are unknown. The aim of these PhD studies was to unravel some mechanisms that might underlie the damage induced by oxygen and the long-term risk of developing vascular and metabolic diseases in the overall concept of developmental programming of hypertension and metabolic syndrome-related diseases. Materials and methods Sprague-Dawley pups were kept with their mother in 80 % O2 (O2) or room air (RA) from day 3 to 10 of life. Cardiovascular parameters, tail blood pressure was measured between 4 and 15 weeks of life. In adulthood : vascular reactivity (ex vivo carotid rings) to angiotensine II (AngII) and carbachol with and without tempol was studied; studies of nitric oxide (NO) production with and without L-arginine and L-sépiaptérine (aorta, immunohistochemistry) and endothelial nitric oxide synthase expression (eNOS; aorta, immunohistochemistry, western blot) were performed; vascular oxidative stress (aorta, using chemiluminescence) by measuring superoxide anion production with and without inhibitors of nicotinamide-adenine-dinucleotide-phosphate (NADPH oxydase) and nitric oxyde synthase endotheliale (eNOS), apocynin and N-nitro-L-arginine methyl ester (L-NAME) respectively, and circulating oxidative stress by measuring the plasma levels of malondialdéhyde (MDA, HPLC) were evaluated; microvascular density was assessed on tibialis anterior muscle sections; pulse wave velocity (PWV) was measured by ultrasound, between aortic valve and ilio-femoral bifurcation; nephrons were counted after hydrochloric acid digestion. The main observations were also evaluated at 4 weeks of age. Metabolic parameters: body weight has been measured during the growth. In adulthood, body composition, glucose tolerance were evaluated. Results A 4 weeks of age, no difference was observed regarding blood pressure, vascular reactivity, and oxidative stress indices, but in rats O2 vs. RA (n = 6-8 /group), microvascular rarefaction and histological changes suggesting enhanced vascular stiffness were present. To adulthood, rats O2 vs. RA (n = 6-8/group) : i) systolic and diastolic blood pressures are increased; ii) vascular reactivity to Ang II is increased and to carbachol is decreased, these dysfunction were totally abolished by co-incubation of the vessel rings with tempol; iii) NO-production is decreased in basal condition and after carbachol stimulation, but is restored after pre-incubation of aorta sections with L- arginine and L-sépiaptérine; iv) eNOS expression is decreased by immunohistochemistry but increased by western blot; v) vascular superoxide anion levels are increased in basal condition, after AngII stimulation and this is mediated by NADPH oxydase and eNOS uncoupling; vi) the plasma levels of MDA are increased; vii) microvascular density is decreased; viii) PWV is increased; ix) nephron count per kidney is decreased; x) body weight is less during growth, but a catch up is observed in adulthood, body composition is similar; xi) the glucose tolerance is decreased in adults. Conclusion These results support the hypothesis of developmental programming of vascular and metabolic diseases in adulthood, after exposure to hyperoxic stress in the neonatal period. / Thèse réalisée dans le cadre d'une cotutelle entre l'Université de Montréal et l'Université d'Auvergne en France