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Exercise prevents fatty liver by modifying the compensatory response of mitochondrial metabolism to excess substrate availability

ABSTRACT: Exercise training is a potent treatment of NAFLD and hepatic insulin resistance. Here we provide molecular information about the hepatic mitochondrial metabolism in mice when chronic overnutrition (high-energy diet (HED) for 6 weeks) is combined with exercise training. Training reduced the hepatic triacylglycerol content, fasting insulin, and reversed glucose intolerance. Training modified the hepatic mitochondrial proteome with a decrease in enzymes related to pyruvate metabolism and entry of acetyl-CoA into the TCA cycle. Transcriptome data revealed down-regulation of glucose oxidation and lipogenesis. The mitochondrial respiratory capacity of trained HED-fed mice is increased despite reduced content of complex I. Training decreased diacylglycerol species and JNK phosphorylation, both of which can induce insulin resistance. Increased mitochondrial mass and oxidative capacity of the trained muscle further unburdens the liver from substrate overload. Together, when high fat and carbohydrate intake in mice is accompanied by exercise, the decline of mitochondrial function and insulin resistance can be prevented by modification of mitochondrial acetyl-CoA metabolism.

ORGANISM(S): Mus musculus

PROVIDER: GSE167046 | GEO | 2021/10/15

REPOSITORIES: GEO

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Project description:Skeletal muscle mitochondrial dysfunction is secondary to T2DM and can be improved by long-term regular exercise training Mitochondrial dysfunction has long been implicated to play a causative role in development of type 2 diabetes (T2DM). However, a growing number of recent studies provide data that mitochondrial dysfunction is a consequence of T2DM development. The aim of our study is to clarify in further detail the causal role of mitochondrial dysfunction in T2DM by a comprehensive ex vivo analysis of mitochondrial function combined with global gene expression analysis in muscle of pre-diabetic newly diagnosed untreated T2DM subjects and long-standing insulin treated T2DM subjects compared with age- and BMI-matched controls. In addition, we assessed the impact of long-term interval exercise training on physical activity performance, mitochondrial function and glycemic control in long-standing insulin-treated T2DM subjects. Ex vivo mitochondrial density, quality and functioning was comparable between pre-diabetic subjects and matched controls, however, gene expression analysis showed a switch from carbohydrate toward lipids as energy source in pre-diabetes subjects. In contrast, long-term insulin treated T2DM subjects had slightly decreased mitochondrial density and ex vivo function. Expression of Krebs cycle and OXPHOS related genes were decreased, indicating a decreased capacity to use lipids as an energy source. The insulin-treated T2DM subjects had a lower physical activity level than pre-diabetic and normoglycemic subjects. A 52 weeks exercise training of these subjects increased submaximal oxidative efficiency, increased in vivo PCr recovery rate, as well as mildly increased in vitro mitochondrial function. Gene expression of β-oxidation, Krebs cycle and OXPHOS-related genes was increased. Our data demonstrate that mitochondrial dysfunction is rather a consequence than a causative factor in T2DM development as it was only detected in overt diabetes and not in early diabetes. Regular exercise training stabilized exogenous insulin requirement and improved mitochondrial functioning, fatty acid oxidation and general physical work load capacity in long-standing insulin-treated T2DM subjects. As such, the present study shows for the first time that long-term exercise interventions are beneficial in this group of complex diabetes patient and may prevent further metabolic deterioration. Insulin-treated T2DM subjects before and after 52 weeks of exercise training (T2DM_0 and T2DM_52), normoglycemic controls (NGT) and pre-diabetes subjects (IGT) and were selected. RNA was extracted from skeletal muscle biopsies and hybridized on Affymetrix microarrays.

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Exercise prevents fatty liver by modifying the compensatory response of mitochondrial metabolism to excess substrate availability

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