Effets sur le métabolisme énergétique mitochondrial myocardique et hépatique de la carence en donneurs de méthyles au cours de la gestation et de l'allaitement chez le raton

Abstract : During development, changes in carbon metabolism related to malnutrition may be deleterious for both the mother and the newborn. In addition, long-term consequences of a methyl deficiency gestational and prenatal are poorly understood. We are particularly interested in studying these effects on the heart and liver. We have used a nutritional model of adult rats deficient in methyl donors (vitamin B12, folate and choline) before pregnancy. To be placed in a context of pathophysiology, close to the clinical situation, we chose to feed the rats with a methyl deficient diet one month before mating and continue this diet during the suckling period. We evaluated the metabolic and functional effects of this diet on myocardial and hepatic tissues, in the newborn pups in 21 days old. We studied the effects of methyl deficient diet on lipid and energy metabolism and carnitine. Consequences of the deficiency at the myocardial: The diet deficient in methyl donors induces cardiac hypertrophy with an increase in myocardial thickness and enlargement of cardiomyocytes. The proteomics analysis of the bioinformatics data identifies PGC-1[alpha], ERR[alpha] and PPAR[alpha] as major determinants of changes in protein expression of mitochondrial oxidative metabolism. We observed a decreased expression of PPAR[alpha] and ERR[alpha] and an inactivation of PGC1[alpha] by hypomethylation and hyperacetylation, in conjunction with a decrease in the expression of PRMT1 and SIRT1 and increased the level of SAH. Consequences of the deficiency at liver: Deficiency is accompanied by the appearance of microvesicular hepatic steatosis, with elevated tissue levels of lipids and triglycerides. Increase of inflammation was observed in this model with no changes in fibrosis score. In this respect, our results showed a deficiency of carnitine synthesis, involved in the beta-oxidation and storage of fatty acids, play a role in the pathogenesis of hepatic steatosis in the newborn. There is also a deregulation of the oxidative metabolism of fatty acids, with decreased activity of complex I and II of the respiratory chain, resulting in hypomethylation of PGC1 and decreased expression of PPAR[alpha], ER[alpha] and ERR[alpha]. In conclusion, our results show that maternal deprivation in methyl donors impaired the function of PGC-1[alpha]. These changes are associated with alterations in fatty acid oxidation and mitochondrial function during the neonatal period, with lipid accumulation in myocardial tissue and liver. The link between the methyl donor deficiency and impaired methylation of PGC-1[alpha] alters the activities of enzymes involved in methylation and acetylation of PGC-1[alpha]. These enzymes are also associated with epigenetic changes and the function and gene expression. Our results are consistent with population studies by Barker and colleagues, who suggest that maternal nutrition during early stages of life is correlated with the risk of cardiovascular disease in adult, independent of other risk factors
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Shabnam Pooya. Effets sur le métabolisme énergétique mitochondrial myocardique et hépatique de la carence en donneurs de méthyles au cours de la gestation et de l'allaitement chez le raton. Médecine humaine et pathologie. Université de Lorraine, 2012. Français. ⟨NNT : 2012LORR0035⟩. ⟨tel-01749205⟩

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