Enhanced calorigenesis in brown adipose tissue in physically trained rats

Area of Science:

• Physiology
• Metabolism
• Exercise Science

Background:

• Brown adipose tissue (BAT) plays a crucial role in thermogenesis.
• Norepinephrine (NE) is a key stimulant of BAT calorigenesis.
• The impact of physical training on BAT's metabolic response requires further elucidation.

Purpose of the Study:

• To quantify the calorigenesis in BAT in response to NE infusion.
• To compare the NE-stimulated calorigenesis in physically trained (TR) rats versus control (CT) rats.
• To determine the contribution of BAT to the whole-body metabolic response to NE following physical training.

Main Methods:

• Rats underwent 18 weeks of daily swimming exercise.
• Calorigenesis was assessed by measuring arteriovenous O2 difference and blood flow in BAT.
• NE was infused at a rate of 4 micrograms/(kg . min) to stimulate calorigenesis.

Main Results:

• NE infusion significantly increased O2 consumption in BAT for both TR and CT rats.
• The increase in BAT O2 consumption was approximately 1.60 ml/min in TR rats versus 0.83 ml/min in CT rats.
• BAT contributed 50% to the whole-body calorigenic response in TR rats, compared to 36% in CT rats.

Conclusions:

• Physical training per se enhances the calorigenic response of brown adipose tissue to norepinephrine.
• Trained rats exhibit a heightened metabolic activity in BAT when stimulated by NE.
• These findings highlight the significant role of physical training in modulating BAT function and energy expenditure.