Changes in PGC-1α-Dependent Mitochondrial Biogenesis Are Associated with Inflexible Hepatic Energy Metabolism in the Offspring Born to Dexamethasone-Treated Mothers

In the present study we investigated the participation of hepatic peroxisome proliferator-activated receptor-gamma coactivator 1 alpha (PGC-1α) in the metabolic programming of newborn rats exposed in utero to dexamethasone (DEX). On the 21st day of life, fasted offspring born to DEX-treated mothers displayed increased conversion of pyruvate into glucose with simultaneous upregulation of PEPCK (phosphoenolpyruvate carboxykinase) and G6Pase (glucose-6-phosphatase). Increased oxidative phosphorylation, higher ATP/ADP ratio and mitochondrial biogenesis and lower pyruvate levels were also found in the progeny of DEX-treated mothers. On the other hand, the 21-day-old progeny of DEX-treated mothers had increased hepatic triglycerides (TAG) and lower CPT-1 activity when subjected to short-term fasting. At the mechanistic level, rats exposed in utero to DEX exhibited increased hepatic PGC-1α protein content with lower miR-29a-c expression. Increased PGC-1α content was concurrent with increased association to HNF-4α and NRF1 and reduced PPARα expression. The data presented herein reveal that changes in the transcription machinery in neonatal liver of rats born to DEX-treated mothers leads to an inflexible metabolic response to fasting. Such programming is hallmarked by increased oxidative phosphorylation of pyruvate with impaired FFA oxidation and hepatic TAG accumulation.</jats:p

MTOR pathway activity in skeletal muscle of offspring is affected by maternal consumption of high fat diet differently between newborns and infants

A redução no desenvolvimento muscular de filhotes cujas mães foram submetidas ao consumo de dietas baseadas no padrão ocidental pode ser, ao menos em parte, explicada pela resistência periférica à insulina, condição na qual a atividade de proteínas relacionadas à via de sinalização intracelular sensível a esse hormônio encontra-se reduzida. A regulação positiva dessa via resulta no aumento da atividade do Alvo da Rapamicina em Mamíferos (mTOR) que atua como efetor positivo da taxa de tradução de RNAm e, consequentemente, da síntese proteica. Estudos que avaliam a atividade dessa proteína frente ao consumo crônico de dietas hiperlipídicas são escassos e controversos e, até o momento, não são conhecidos trabalhos que avaliaram esses marcadores em animais neonatos ou desmamados, provenientes de mães alimentadas com dieta hiperlipídica gestacional e pós-gestacional. O presente estudo objetiva avaliar o efeito do consumo de uma dieta hiperlipídica por ratas adultas sobre a morfologia e sobre a expressão e a fosforilação das proteínas que compõem a via de sinalização intracelular do mTOR no músculo esquelético da prole em dois momentos: nascimento e desmame. Para isso, inicialmente, 39 ratas foram distribuídas em dois grupos, de acordo com a dieta oferecida: controle (n=19) e hiperlipídica (n=20). Após o nascimento, cerca de seis filhotes por mãe foram eutanasiados para coleta de amostras e análise dos marcadores investigados. Os filhotes selecionados para dar continuidade ao experimento foram dispostos junto às mães que, por sua vez, foram distribuídas em outros quatro grupos, segundo a dieta gestacional e pós-gestacional: CON/CON (n=8); CON/HL (n=9); HL/HL (n=8); HL/CON (n=7). Ao final da lactação, os filhotes foram eutanasiados e amostras foram coletadas para análise. Os resultados obtidos indicam que, em relação aos animais neonatos, há redução das concentrações séricas de leptina e de IGF-I e aumento da fosforilação da Akt e do mTOR musculares, em resposta ao consumo materno da dieta hiperlipídica. Por sua vez, nos animais lactentes, observamos influência da dieta hiperlipídica materna pós-gestacional sobre a promoção de fenótipo obesogênico, com concomitante redução do desenvolvimento muscular e da fosforilação de proteínas alvo do mTOR em estado pós-prandial. Com base nos resultados obtidos, concluímos que a dieta hiperlipídica materna afeta a atividade do mTOR, sendo, esse efeito, dependente da idade e da condição fisiológica dos animais.The decrease in muscle development of offspring whose mothers consume a typical Western diet can be partly explained by the progression of peripheral insulin resistance, a condition in which the activity of proteins related to the intracellular signaling pathway sensitive to this hormone is reduced. The positive regulation of this pathway results in increased activity of the Mammalian Target of Rapamycin (mTOR) that acts as a positive regulator of the rate of mRNA translation and protein synthesis. Studies that assess the activity of this protein in response to chronic consumption of high fat diets are scarce and controversial and, to date, studies that evaluated these markers in the offspring of mothers fed a high fat diet during gestational and lactation are not known. This study aims to evaluate the effect of consuming a high fat diet for female adult rats in morphology and expression and phosphorylation of proteins that comprise the intracellular signaling pathway of mTOR in skeletal muscle of offspring in two stages: birth and weaning. Therefore, initially, 39 rats were divided into two groups, according to the available diet: control (n = 19) and diet (n = 20). After birth, around six pups per mother were killed for sample collection and analysis of the markers investigated. The pups selected to continue the experiment were placed with the mothers who, in turn, were divided into four groups according to gestational and post-gestational diets: CON/CON (n = 8), CON/HL (n = 9), HL/HL (n = 8), HL/CON (n = 7). At the end of lactation, the pups were euthanized and samples were collected for analysis. The results indicate that, for the newborn animals, there is a reduction of serum leptin and IGF-I concentrations and increased phosphorylation of Akt and mTOR in muscle in response to maternal consumption of high fat diet. In turn, we found that maternal high-fat diet during lactation promoted an obese phenotype in weaned animals, with concomitant reduction of muscle development and mTOR target proteins phosphorylation in the postprandial state. Based on these results, we conclude that maternal high-fat diet affects the activity of mTOR, depending on age and physiological condition of the animals

Programming by glucocorticoid excess: actions of miRNAs on hepatic development and outcome.

Avaliamos o efeito da RCIU induzida por glicocorticoides sobre a regulação da expressão de miRNAs no fígado de ratos albinos. Animais expostos intrauterinamente à dexametasona apresentaram menor peso ao nascer, fígados relativamente menores dos que os observados em animais controle e menores concentrações hepáticas de PCNA. Em longo prazo, os animais DEX desenvolveram distúrbios metabólicos caracterizados por intolerância à glicose e maior potencial gliconeogênico no desmame e na vida adulta. Ao avaliarmos o perfil de miRNAs no fígado, detectamos aumento da expressão de todo o cluster do miR-322 no período perinatal, com menor conteúdo de alvos preditos desses transcritos (AKT3, CCND1 e INSR). A superexposição ao miR-322-5P reduz a taxa de proliferação em linhagens celulares de hepatocarcinoma e a expressão dos alvos observados no fígado dos animais estudados. Propomos um link entre a expressão aberrante do miR-322-5P e a reduzida taxa de proliferação detectada no tecido hepático em desenvolvimento, contribuindo para o estabelecimento do fenótipo em longo prazo.We evaluated the effects of glucocorticoid induced IUGR on the expression of miRNA on Wistar rat livers. Dexamethasone (DEX) treated animals were lighter and had smaller liver weight:body weight ratio when compared to control animals. Furthermore, liver PCNA expression was downregulated, sugesting a reduction on cell proliferation rate. In the long term, DEX animals developed metabolic disturbances such as glucose intolerance e increased gluconeogenesis rate in a fast state. The analysis of miRNA expression profile showed an upregulation of miR-322 cluster on perinatal period, together with a downregulation of three putative targets: Akt3, CCND1 and INSR. Later, we used in vitro studies to prove that overexpression of miR-322-5P arrests cell cycle and impairs proliferation of HEPG2 cells as well as it downregulates the predicted targets. Based on this data, we suggest a link between overexpression of miR-322-5P and impaired proliferation rate on the developing liver, which affects the phenotype in the long term

MTOR pathway activity in skeletal muscle of offspring is affected by maternal consumption of high fat diet differently between newborns and infants

A redução no desenvolvimento muscular de filhotes cujas mães foram submetidas ao consumo de dietas baseadas no padrão ocidental pode ser, ao menos em parte, explicada pela resistência periférica à insulina, condição na qual a atividade de proteínas relacionadas à via de sinalização intracelular sensível a esse hormônio encontra-se reduzida. A regulação positiva dessa via resulta no aumento da atividade do Alvo da Rapamicina em Mamíferos (mTOR) que atua como efetor positivo da taxa de tradução de RNAm e, consequentemente, da síntese proteica. Estudos que avaliam a atividade dessa proteína frente ao consumo crônico de dietas hiperlipídicas são escassos e controversos e, até o momento, não são conhecidos trabalhos que avaliaram esses marcadores em animais neonatos ou desmamados, provenientes de mães alimentadas com dieta hiperlipídica gestacional e pós-gestacional. O presente estudo objetiva avaliar o efeito do consumo de uma dieta hiperlipídica por ratas adultas sobre a morfologia e sobre a expressão e a fosforilação das proteínas que compõem a via de sinalização intracelular do mTOR no músculo esquelético da prole em dois momentos: nascimento e desmame. Para isso, inicialmente, 39 ratas foram distribuídas em dois grupos, de acordo com a dieta oferecida: controle (n=19) e hiperlipídica (n=20). Após o nascimento, cerca de seis filhotes por mãe foram eutanasiados para coleta de amostras e análise dos marcadores investigados. Os filhotes selecionados para dar continuidade ao experimento foram dispostos junto às mães que, por sua vez, foram distribuídas em outros quatro grupos, segundo a dieta gestacional e pós-gestacional: CON/CON (n=8); CON/HL (n=9); HL/HL (n=8); HL/CON (n=7). Ao final da lactação, os filhotes foram eutanasiados e amostras foram coletadas para análise. Os resultados obtidos indicam que, em relação aos animais neonatos, há redução das concentrações séricas de leptina e de IGF-I e aumento da fosforilação da Akt e do mTOR musculares, em resposta ao consumo materno da dieta hiperlipídica. Por sua vez, nos animais lactentes, observamos influência da dieta hiperlipídica materna pós-gestacional sobre a promoção de fenótipo obesogênico, com concomitante redução do desenvolvimento muscular e da fosforilação de proteínas alvo do mTOR em estado pós-prandial. Com base nos resultados obtidos, concluímos que a dieta hiperlipídica materna afeta a atividade do mTOR, sendo, esse efeito, dependente da idade e da condição fisiológica dos animais.The decrease in muscle development of offspring whose mothers consume a typical Western diet can be partly explained by the progression of peripheral insulin resistance, a condition in which the activity of proteins related to the intracellular signaling pathway sensitive to this hormone is reduced. The positive regulation of this pathway results in increased activity of the Mammalian Target of Rapamycin (mTOR) that acts as a positive regulator of the rate of mRNA translation and protein synthesis. Studies that assess the activity of this protein in response to chronic consumption of high fat diets are scarce and controversial and, to date, studies that evaluated these markers in the offspring of mothers fed a high fat diet during gestational and lactation are not known. This study aims to evaluate the effect of consuming a high fat diet for female adult rats in morphology and expression and phosphorylation of proteins that comprise the intracellular signaling pathway of mTOR in skeletal muscle of offspring in two stages: birth and weaning. Therefore, initially, 39 rats were divided into two groups, according to the available diet: control (n = 19) and diet (n = 20). After birth, around six pups per mother were killed for sample collection and analysis of the markers investigated. The pups selected to continue the experiment were placed with the mothers who, in turn, were divided into four groups according to gestational and post-gestational diets: CON/CON (n = 8), CON/HL (n = 9), HL/HL (n = 8), HL/CON (n = 7). At the end of lactation, the pups were euthanized and samples were collected for analysis. The results indicate that, for the newborn animals, there is a reduction of serum leptin and IGF-I concentrations and increased phosphorylation of Akt and mTOR in muscle in response to maternal consumption of high fat diet. In turn, we found that maternal high-fat diet during lactation promoted an obese phenotype in weaned animals, with concomitant reduction of muscle development and mTOR target proteins phosphorylation in the postprandial state. Based on these results, we conclude that maternal high-fat diet affects the activity of mTOR, depending on age and physiological condition of the animals

Low Birth Weight Intensifies Changes in Markers of Hepatocarcinogenesis Induced by Fructose Consumption in Rats.

Peer reviewed: TrueFunder: Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Intrauterine growth restriction (IUGR) due to fetal exposure to glucocorticoid excess results in metabolic inflexibility and hepatic steatosis upon nutritional stress during adulthood. We previously demonstrated that rats born to dexamethasone (DEX)-treated mothers developed hepatic steatosis when exposed to 10% fructose solution during adult life. Persistent triacylglyceride (TAG) accumulation in the liver, in turn, is a feature of non-alcoholic fatty liver disease (NAFLD), which serves as a risk factor for non-alcoholic steatohepatitis (NASH) and hepatocellular carcinoma (HCC). In the present study, we demonstrate that the combination of IUGR and fructose treatment during adulthood also results in increased hepatic myeloperoxidase (MPO) activity, AKT phosphorylation and serum aspartate transaminase. Growth-restricted rats also presented reduced hepatic TRIB3 and GADD45a after fructose treatment. Other markers of cell proliferation, such as Cyclin D, PCNA, Hgf and Hspa4/Hsp70 expression and the number of Ki-67 positive cells, were all increased in the liver of growth- restricted rats treated with fructose. On the other hand, the combination of IUGR and fructose treatment during adult life reduced the levels of IGF-1. In conclusion, our data indicate that after exposure to fructose, adult rats subjected to dexamethasone-induced IUGR display exacerbated molecular changes in markers of NASH and HCC

Changes in PGC-1α-Dependent Mitochondrial Biogenesis Are Associated with Inflexible Hepatic Energy Metabolism in the Offspring Born to Dexamethasone-Treated Mothers

In the present study we investigated the participation of hepatic peroxisome proliferator-activated receptor-gamma coactivator 1 alpha (PGC-1α) in the metabolic programming of newborn rats exposed in utero to dexamethasone (DEX). On the 21st day of life, fasted offspring born to DEX-treated mothers displayed increased conversion of pyruvate into glucose with simultaneous upregulation of PEPCK (phosphoenolpyruvate carboxykinase) and G6Pase (glucose-6-phosphatase). Increased oxidative phosphorylation, higher ATP/ADP ratio and mitochondrial biogenesis and lower pyruvate levels were also found in the progeny of DEX-treated mothers. On the other hand, the 21-day-old progeny of DEX-treated mothers had increased hepatic triglycerides (TAG) and lower CPT-1 activity when subjected to short-term fasting. At the mechanistic level, rats exposed in utero to DEX exhibited increased hepatic PGC-1α protein content with lower miR-29a-c expression. Increased PGC-1α content was concurrent with increased association to HNF-4α and NRF1 and reduced PPARα expression. The data presented herein reveal that changes in the transcription machinery in neonatal liver of rats born to DEX-treated mothers leads to an inflexible metabolic response to fasting. Such programming is hallmarked by increased oxidative phosphorylation of pyruvate with impaired FFA oxidation and hepatic TAG accumulation

Changes in PGC-1α-Dependent Mitochondrial Biogenesis Are Associated with Inflexible Hepatic Energy Metabolism in the Offspring Born to Dexamethasone-Treated Mothers

In the present study we investigated the participation of hepatic peroxisome proliferator-activated receptor-gamma coactivator 1 alpha (PGC-1α) in the metabolic programming of newborn rats exposed in utero to dexamethasone (DEX). On the 21st day of life, fasted offspring born to DEX-treated mothers displayed increased conversion of pyruvate into glucose with simultaneous upregulation of PEPCK (phosphoenolpyruvate carboxykinase) and G6Pase (glucose-6-phosphatase). Increased oxidative phosphorylation, higher ATP/ADP ratio and mitochondrial biogenesis and lower pyruvate levels were also found in the progeny of DEX-treated mothers. On the other hand, the 21-day-old progeny of DEX-treated mothers had increased hepatic triglycerides (TAG) and lower CPT-1 activity when subjected to short-term fasting. At the mechanistic level, rats exposed in utero to DEX exhibited increased hepatic PGC-1α protein content with lower miR-29a-c expression. Increased PGC-1α content was concurrent with increased association to HNF-4α and NRF1 and reduced PPARα expression. The data presented herein reveal that changes in the transcription machinery in neonatal liver of rats born to DEX-treated mothers leads to an inflexible metabolic response to fasting. Such programming is hallmarked by increased oxidative phosphorylation of pyruvate with impaired FFA oxidation and hepatic TAG accumulation