Mise en évidence de plusieurs transcrits de la γ-butyrobétaine hydroxylase

Ghrelin reduces hepatic mitochondrial fatty acid beta oxidation.

Ghrelin is a 28-amino-acid peptide secreted during starvation by gastric cells. Ghrelin physiologically induces food intake and seems to alter lipid and glucid metabolism in several tissues such as adipose tissue and liver. Liver has a key position in lipid metabolism as it allows the metabolic orientation of fatty acids between oxidation and esterification. We investigated the effects of peripheral ghrelin administration on 2 crucial parameters of fatty acid oxidation: the levocarnitine (L-carnitine)-dependent entry of the fatty acids in the mitochondria and the mitochondrial fatty acid oxidation. Ghrelin was either given to rats prior to the hepatocyte preparation and culture or used to t…

Carnitine et performance physique

Resume Objectif. – L’objectif de cette publication est de preciser l’implication de la carnitine dans le fonctionnement normal de la cellule musculaire et d’evaluer l’interet que pourrait representer pour les performances physiques une supplementation en carnitine. Actualites. – Recemment, de nouvelles informations concernant la voie de la biosynthese de la carnitine ainsi que de son transport dans les cellules musculaires ont ete publiees. Les bases moleculaires des deficiences en carnitine ont notamment ete identifiees permettant ainsi de mieux comprendre les mecanismes controlant l’utilisation de la carnitine dans ces cellules. Une analyse aussi exhaustive que possible a ete menee afin d…

Thyroid hormone controls carnitine status through modifications of gamma-butyrobetaine hydroxylase activity and gene expression.

The carnitine system plays a key role in beta-oxidation of long-chain fatty acids by permitting their transport into the mitochondrial matrix. The effects of hypothyroidism and hyperthyroidism were studied on gamma-butyrobetaine hydroxylase (BBH), the enzyme responsible for carnitine biosynthesis in the rat. In rat liver, BBH activity was decreased in the hypothyroid state and increased in hyperthyroid animals. The modifications in BBH activity correlated with changes in the enzyme Vmax values. These changes were shown to be related to hepatic BBH mRNA abundance. Thyroid hormones are known to interact with lipid metabolism, in particular by increasing long-chain fatty acid oxidation through…