Intestinal PPAR? signalling is required for sympathetic nervous system activation in response to caloric restriction.

ABSTRACT: Nuclear receptor PPAR? has been proven to affect metabolism in multiple tissues, and has received considerable attention for its involvement in colon cancer and inflammatory disease. However, its role in intestinal metabolism has been largely ignored. To investigate this potential aspect of PPAR? function, we submitted intestinal epithelium-specific PPAR? knockout mice (iePPAR?KO) to a two-week period of 25% caloric restriction (CR), following which iePPAR?KO mice retained more fat than their wild type littermates. In attempting to explain this discrepancy, we analysed the liver, skeletal muscle, intestinal lipid trafficking, and the microbiome, none of which appeared to contribute to the adiposity phenotype. Interestingly, under conditions of CR, iePPAR?KO mice failed to activate their sympathetic nervous system (SNS) and increase CR-specific locomotor activity. These KO mice also manifested a defective control of their body temperature, which was overly reduced. Furthermore, the white adipose tissue of iePPAR?KO CR mice showed lower levels of both hormone-sensitive lipase, and its phosphorylated form. This would result from impaired SNS signalling and possibly cause reduced lipolysis. We conclude that intestinal epithelium PPAR? plays an essential role in increasing SNS activity under CR conditions, thereby contributing to energy mobilization during metabolically stressful episodes.

SUBMITTER: Duszka K 

PROVIDER: S-EPMC5113069 | biostudies-other | 2016 Nov

REPOSITORIES: biostudies-other