Made available in DSpace on 2016-06-02T19:22:54Z (GMT). No. of bitstreams: 1 3708.pdf: 1832154 bytes, checksum: 29e11e4137bb04f771b2ba6bb3dd6c96 (MD5) Previous issue date: 2011-06-17 / Financiadora de Estudos e Projetos / Decreased levels of estrogen are associated with hepatic steatosis (HS), through changes in gene expression of molecules related to fat oxidation and lipogenesis. Both resistance training (RT) and endurance training (ET) prevents the HS in ovariectomized (Ovx) rats. However, the molecular events associated with this process were only investigated for ET but not for RT. Aims: Thus, the aim of this study was to investigate the effects of Ovx and RT on the gene expression of molecules related to fat oxidation and lipogenesis in the liver of rats. Methods: Sprague-Dawley adult female rats were grouped into four groups (n = 6 per group): sham-operated sedentary (Sham-Sed); Ovx sedentary (Ovx-Sed); sham-Rt and Ovx- Rt. A 10-week RT period, during which the animals climbed a 1.1-m vertical ladder with weights attached to their tails, was used. The sessions were performed three times a week, with 4-9 climbs and 8-12 dynamic movements per climb. Gene expression was analyzed by RT-PCR by the ΔΔCt method. Results: The estrogen deficiency associated with ovariectomy decreased the gene expression of molecules related to fat oxidation, carnitine palmitoyltransferase I (53%) and β-hydroxyacyl-CoA dehydrogenase (27%), and increased of molecules related to lipogenesis, sterol regulatory element-binding protein-1c (106%), acetyl-CoA carboxilase (ACC) (72%) and stearoyl CoA desaturase-1 (109%), which had their expression restored to the RT, with the exception of the ACC. Conclusions: The present results indicate that the RT may have important effects on the prevention of HS in Ovx animals, possibly through the restoration in gene expression of molecules related to hepatic lipid metabolism / A deficiência de estrógeno está associada à esteatose hepática (EH), por meio de alteração na expressão gênica de moléculas relacionadas à oxidação de gordura e à lipogênese. Tanto o treinamento resistido (TR), quanto o treinamento de endurance (TE) previne a EH em ratas ovariectomizadas (Ovx). No entanto, os eventos moleculares somente foram investigados em relação ao TE e não ao TR. Objetivo: investigar os efeitos da Ovx e do TR sobre a expressão gênica de moléculas relacionadas tanto a oxidação de gordura quanto a lipogênese no fígado de ratas. Métodos: Ratas Sprague-Dawley adultas foram divididas em 4 grupos (n = 6 por grupo): sham operado sedentário (Sham-Sed), Ovx sedentário (Ovx-Sed), sham operado TR (Sham-Tr) e Ovx-Tr. O protocolo de TR exigiu dos animais a escalada de uma escada vertical de 1,1 m com pesos atados as suas caudas. Cada sessão consistiu de 4-9 escaladas, com intervalo de 2 min entre as escaladas, realizado com freqüência semanal de 3 vezes durante 10 semanas. A análise da expressão gênica foi realizada por PCR-RT pelo método ΔΔCt. Resultados: A Ovx diminui significativamente a expressão gênica das moléculas relacionadas à oxidação de gordura; carnitina palmitoil transferase I 53% e da hidroxiacil-CoA desidrogenase 27%, e aumentou das moléculas relacionadas com a lipogênese; proteína 1c ligadora do elemento regulado por esteróis 106%, acetil-CoA carboxilase 72% e estearoil-CoA dessaturase-1 109%, as quais tiveram suas expressões restauradas com o TR, com exceção da ACC. Conclusão: Os resultados presentes sugerem que o TR pode ter importantes efeitos sobre a prevenção da EH em animais Ovx, possivelmente por meio da restauração da expressão gênica de moléculas relacionadas ao metabolismo lipídico hepático.

La pharmacopée Cris est riche en plantes médicinales et plusieurs d’entre elles sont étudiées par notre laboratoire pour leur potentiel antidiabétique. Certaines espèces ont démontré leur capacité à stimuler la protéine kinase activée par l’AMP (AMPK), une enzyme qui favorise la translocation de transporteurs de glucose à la membrane (effet hypoglycémiant). L’AMPK stimule également d’autres fonctions, telle l’oxydation des graisses, dans le but de rétablir l’énergie cellulaire. Ce projet a comme objectifs d’évaluer, premièrement, le stress métabolique induit par huit des extraits dans des cellules musculaires et des hépatocytes, effet qui serait responsable de l’activation de l’AMPK. Ce stress peut être déterminé en mesurant l’acidification du milieu extracellulaire ainsi que la déplétion du contenu en ATP des cellules suite aux traitements. Le deuxième objectif est de mesurer l’efficacité des extraits à réduire le contenu en gras (oxydation des graisses) et à ainsi normaliser la résistance à l’insuline dans des hépatocytes rendus insulino-résistants. Les hépatocytes sont rendus résistants à l’insuline (condition fortement lié à l’obésité) via traitement avec un acide gras saturé, le palmitate. Les résultats montrent que la majorité des extraits semble induire un stress métabolique de courte durée dans les cellules. Parmi les extraits, seul un a réussi à faire diminuer significativement le taux de triglycérides intracellulaire suite au traitement au palmitate sans toutefois améliorer la sensibilité à l’insuline. En conclusion, le potentiel hypoglycémiant des extraits serait du à leur capacité à affecter la respiration mitochondriale (stress métabolique). Toutefois, leur capacité à améliorer la sensibilité à l’insuline n’a pu être établie. / Cree pharmacopeia is rich in medicinal plants and many of them are studied by our laboratory for their antidiabetic potential. Some of the species tested have shown to activate the AMP-activated protein kinase (AMPK), an enzyme responsible for the translocation of glucose transporters to the cell membrane (hypoglycaemic activity). AMPK is also known to activate other cellular functions, like fat oxidation, in order to restore cell energy loss. The objectives of this study are, first, to measure the metabolic stress induced by eight of the species in muscular and liver cells, an effect believed to be responsible for the AMPK activation. Metabolic stress is evaluated by measuring extracellular medium acidification and cellular ATP depletion. The second objective is to assess the capacity of the extracts to clear intracellular fat (fat oxidation) and, by doing this, restore insulin sensitivity in insulin-resistant driven hepatocytes. To become insulin-resistant (a condition strongly linked to obesity), the hepatocytes are treated with a saturated fatty acid, palmitate. The results show that most of the extracts seem to increase the metabolic stress in muscular cells and hepatocytes for a short period of time. Among all extracts, only one has significantly reduced intracellular triglycerides in palmitate treated hepatocytes, an effect not followed by an increase in insulin sensitivity. In conclusion, the species tested in this study seem to exert their hypoglycaemic potential by affecting mitochondrial respiration (metabolic stress). However, the experimentations have not clearly shown the capacity of the species to restore insulin sensitivity in insulin-resistant liver cells.

The primary objective of this PhD program was to investigate the impact of training at a constant-load moderate-intensity (FATmax) compared to work-matched high-intensity intervals (HIIT) on the metabolic, physiological and psychosocial health profiles of sedentary overweight and obese men. This study was unique in that it was the first time the effect of exercise intensity had been investigated to examine concurrently the components of whole-body energy metabolism and body composition as measured using gold standard techniques. Based upon the positive alterations in blood lipids, body composition, cardiorespiratory fitness and substrate oxidation, it appears that training at FATmax can positively impact health parameters as well as, or if not better than, high-intensity training. Furthermore, there are ramifications for public health messages and obesity management strategies arising from these findings, primarily attributable to the increased exercise adherence and the reduction in health risks stemming from the significant loss of abdominal visceral adipose tissue after FATmax training.