Melatonin multiple effects on brown adipose tissue molecular machinery

Area of Science:

• Metabolic Physiology
• Endocrinology
• Chronobiology

Background:

• Brown adipose tissue (BAT) is vital for energy balance via nonshivering thermogenesis.
• Melatonin regulates BAT metabolism, but its precise role in molecular machinery and daily variations is not fully understood.

Purpose of the Study:

• To investigate the role of melatonin in the molecular regulation of BAT in response to metabolic challenges.
• To assess the impact of melatonin absence and replacement on BAT gene and protein expression, daily rhythmicity, and mitochondrial function.

Main Methods:

• Pinealectomized (PINX) and melatonin-treated (PINX/Mel) adult male rats were used.
• BAT was collected across 24-hour cycles and after acute cold or high-fat diet (HFD) exposure.
• Gene expression (Dio2, Ucp1, Cidea, etc.), protein expression, and mitochondrial enzyme activity were analyzed.

Main Results:

• Melatonin absence in PINX rats impaired BAT responses to HFD and cold, altering gene expression and daily rhythmicity.
• Melatonin treatment in PINX/Mel rats restored or enhanced expression of key thermogenic genes (Dio2, Ucp1, Cidea) and mitochondrial function.
• Melatonin normalized altered daily profiles of gene and protein expression in BAT under sub-thermoneutral conditions.

Conclusions:

• Melatonin is essential for maintaining BAT's molecular machinery, daily rhythmicity, and response to metabolic challenges.
• Melatonin replacement effectively reverses impairments caused by its absence, highlighting its critical role in thermogenic activation and organismal homeostasis.