Increased whole body energy expenditure and protection against diet-induced obesity in Cyp8b1-deficient mice is accompanied by altered adipose tissue features
Forskningsoutput: Tidskriftsbidrag › Artikel i vetenskaplig tidskrift
The aim of this study was to elucidate mechanisms whereby bile acids exert beneficial metabolic effects, using the Cyp8b1−/- mouse as model. These mice are unable to synthesize cholic acid, resulting in increased synthesis of chenodeoxycholic acid and enlarged bile acid pool. Cyp8b1−/- mice were found to be protected against high-fat diet induced obesity. Bomb calorimetry measurements showed increased faecal energy output in Cyp8b1−/ mice. Indirect calorimetry measurements demonstrated increased energy expenditure in Cyp8b1−/- mice. Meal tolerance tests revealed no differences in glucose disposal, but the insulin response was lower in Cyp8b1−/- mice. Intravenous glucose tolerance tests, as well as static incubations of isolated islets, showed no difference between the groups, whereas insulin tolerance tests demonstrated improved insulin sensitivity in Cyp8b1−/- mice. The genes encoding mitochondrial transcription factor A (TFAM) and type 2-iodothyronine deiodinase were upregulated in brown adipose tissue of Cyp8b1/- mice and Western blot analyses showed increased abundance of TFAM, and a trend towards increased abundance of UCP1. The upregulation of TFAM and UCP1 was accompanied by increased mitochondrial density, as shown by transmission electron microscopy. White adipocytes of Cyp8b1−/- mice exhibited increased responsiveness to both catecholamines and insulin in lipolysis experiments and increased insulin-stimulated lipogenesis. In conclusion, increased energy expenditure, mitochondrial density of brown adipocytes and faecal energy output may all contribute to the protection against diet-induced obesity of Cyp8b1−/- mice. Enhanced insulin sensitivity of Cyp8b1−/- mice is accompanied by increased hormonal responsiveness of white adipocytes.
|Enheter & grupper|
Ämnesklassifikation (UKÄ) – OBLIGATORISK
|Status||Published - 2020|
|Peer review utförd||Ja|