Dexamethasone Inhibits White Adipose Tissue Browning

Area of Science:

• Adipose tissue biology
• Metabolic regulation
• Endocrinology

Background:

• White adipose tissue (WAT) is crucial for energy homeostasis via storage, secretion, and thermogenesis.
• Beige adipocytes within WAT mediate thermogenesis through a process called browning.
• Glucocorticoids (GCs) influence WAT, but their role in browning and beige adipocyte generation is unclear.

Purpose of the Study:

• To investigate the effect of dexamethasone (DXM), a synthetic glucocorticoid, on WAT thermogenesis.
• To elucidate DXM's impact on beige adipocyte differentiation and function.
• To assess DXM's influence on the WAT browning process.

Main Methods:

• Rats were treated with DXM under room temperature and cold conditions to measure thermogenic markers.
• In vitro studies assessed DXM's effects on beige precursor cell adipogenesis.
• In vitro experiments evaluated DXM's impact on mature beige adipocyte thermogenic gene expression and mitochondrial respiration.

Main Results:

• DXM treatment reduced uncoupling protein 1 (UCP-1) mRNA and protein levels, particularly during cold exposure.
• In vitro, DXM impaired beige precursor differentiation by decreasing Ebf2 expression.
• DXM inhibited the thermogenic response of mature beige adipocytes, evidenced by reduced UCP-1, Dio2, and Pgc1α gene expression and mitochondrial respiration.

Conclusions:

• Dexamethasone significantly inhibits the thermogenic program in both retroperitoneal and inguinal WAT depots.
• DXM's inhibitory effects may stem from reduced de novo beige adipocyte generation and impaired function of mature beige adipocytes.
• These findings suggest GCs could negatively impact WAT browning and thermogenesis, with implications for metabolic health.