Different action of glucocorticoid receptor in adipose tissue remodelling to modulate energy homeostasis by chronic restraint stress.

BACKGROUND

Chronic stress in daily life is a well-known trigger for various health issues. Despite advancements in obesity research, the mechanisms governing lipid metabolism in adipose tissue during cachexia remain poorly understood.

METHODS

A chronic restraint stress (CRS) model was used to induce significant physiological and psychological stress in mice. Mice were subjected to 6 h of restraint daily in 50 mL plastic tubes for seven consecutive days. A fasting control group was included for comparison. Post-stress assessments included behavioural tests, glucose and insulin tolerance tests and indirect calorimetry. Blood and adipose tissue samples were collected for mRNA and protein analyses.

RESULTS

CRS induced significant psychological and physiological changes in mice, including depression-like behaviours, weight loss and reduced insulin sensitivity. Notably, CRS caused extensive adipose tissue remodelling. White adipose tissue (WAT) underwent significant 'browning' accompanied by an increase in the expression of thermogenic proteins. This counteracted the stress-induced 'whitening' of brown adipose tissue (BAT), which exhibited impaired thermogenesis and functionality, thereby maintaining energy balance systematically. The glucocorticoid receptor (GR) plays a crucial role in lipid metabolism regulation during these changes. GR expression levels were inversely correlated in BAT and WAT, but aligned with the expression patterns of thermogenic proteins across adipose tissues. These findings suggest that under chronic metabolic stress, GR mediates tissue-specific responses in adipose tissues, driving functional and phenotypic transitions in BAT and WAT to maintain energy homeostasis.

CONCLUSIONS

This study provides novel insights into the contrasting thermogenic phenotypes of BAT and WAT under emaciation and highlights the critical role of GRs in adipose tissue remodelling during CRS and its potential as a therapeutic target. Addressing GR-mediated changes in adipose tissues may help alleviate BAT dysfunction in cachexia and promote WAT browning, enhancing metabolic stress resistance.