Publication Date
12-1-2024
Journal
Aging Cell
DOI
10.1111/acel.14321
PMID
39177077
PMCID
PMC11634714
PubMedCentral® Posted Date
8-23-2024
PubMedCentral® Full Text Version
Post-print
Published Open-Access
yes
Keywords
Animals, Thermogenesis, Adipose Tissue, Brown, Adipose Tissue, White, Mice, Mice, Inbred C57BL, Receptors, Adrenergic, beta-3, Aging, Energy Metabolism, Adrenergic beta-3 Receptor Agonists, Male, Dioxoles, Uncoupling Protein 1, adipose metabolism, aging, and fatty acid oxidation, beta‐3 adrenergic agonists, energy expenditure, futile substrate cycling, glucose metabolism, lipolysis, thermogenesis, uncoupling protein 1
Abstract
Adipose thermogenesis has been actively investigated as a therapeutic target for improving metabolic dysfunction in obesity. However, its applicability to middle-aged and older populations, which bear the highest obesity prevalence in the United States (approximately 40%), remains uncertain due to age-related decline in thermogenic responses. In this study, we investigated the effects of chronic thermogenic stimulation using the β3-adrenergic (AR) agonist CL316,243 (CL) on systemic metabolism and adipose function in aged (18-month-old) C57BL/6JN mice. Sustained β3-AR treatment resulted in reduced fat mass, increased energy expenditure, increased fatty acid oxidation and mitochondrial activity in adipose depots, improved glucose homeostasis, and a favorable adipokine profile. At the cellular level, CL treatment increased uncoupling protein 1 (UCP1)-dependent thermogenesis in brown adipose tissue (BAT). However, in white adipose tissue (WAT) depots, CL treatment increased glycerol and lipid de novo lipogenesis (DNL) and turnover suggesting the activation of the futile substrate cycle of lipolysis and reesterification in a UCP1-independent manner. Increased lipid turnover was also associated with the simultaneous upregulation of proteins involved in glycerol metabolism, fatty acid oxidation, and reesterification in WAT. Further, a dose-dependent impact of CL treatment on inflammation was observed, particularly in subcutaneous WAT, suggesting a potential mismatch between fatty acid supply and oxidation. These findings indicate that chronic β3-AR stimulation activates distinct cellular mechanisms that increase energy expenditure in BAT and WAT to improve systemic metabolism in aged mice. Considering that people lose BAT with aging, activation of futile lipid cycling in WAT presents a novel strategy for improving age-related metabolic dysfunction.
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