PPARγ activation attenuates cold-induced upregulation of thyroid status and brown adipose tissue PGC-1α and D2

Area of Science:

• Endocrinology
• Metabolism
• Adipose Tissue Biology

Background:

• Brown adipose tissue (BAT) plays a crucial role in thermogenesis and energy expenditure.
• Peroxisome proliferator-activated receptor gamma (PPARγ) is a key regulator of adipogenesis and metabolic function.
• Cold exposure activates BAT through sympathetic nervous system and thyroid hormone signaling.

Purpose of the Study:

• To investigate the effect of pharmacological PPARγ activation on early events of BAT recruitment during acute cold exposure.
• To elucidate the interplay between sympathetic and PPARγ signaling in cold-induced BAT activation.
• To understand how PPARγ activation influences thyroid hormone metabolism and adrenergic signaling in BAT.

Main Methods:

• Sprague-Dawley rats were treated with rosiglitazone (a PPARγ ligand) or vehicle.
• Rats were exposed to cold (5°C) or kept at thermoneutrality (23°C) for 24 hours.
• Assessed BAT gene expression (D2, PGC-1α, THRβ), sympathetic activity, thyroid status (T4, T3), cAMP levels, PKA activity, and CREB binding.

Main Results:

• Rosiglitazone did not alter the cold-induced increase in BAT sympathetic activity or energy expenditure.
• PPARγ activation attenuated cold-induced increases in serum thyroid hormones (T4, T3) and BAT D2 and PGC-1α mRNA levels.
• Rosiglitazone potentiated the cold-induced reduction in BAT THRβ mRNA and reduced CREB binding protein expression.

Conclusions:

• Pharmacological PPARγ activation impairs short-term cold-induced BAT recruitment by disrupting thyroid and adrenergic signaling.
• This impairment may lead to abnormal BAT tissue recruitment and reduced thermogenic capacity.
• Interactions between PPARγ and cold-induced signaling pathways are critical for effective BAT function.