Perivascular adipose tissue: friend or foe to age-related aortic stiffness

Introduction: Previous reports have demonstrated that Aortic Perivascular Adipose Tissue (APVAT), when left intact, makes a young aorta less stiff. However, little is known about how the APVAT phenotype changes with age and how these changes directly influence aortic stiffness. Purpose: The purpose of this study was 1) determine how the APVAT phenotype changes with age and 2) to determine whether the aging APVAT directly influences age-related aortic stiffness. Methods: Young (4-6mo) and Old (22-24mo) male mice were utilized (n-3-10/group). Ex vivo mechanical aortic stiffness with and without the APVAT intact was determined using a wire myograph in calcium free solution. Collagen and adipocyte size was determined via histology. Gene expression was quantified using the ΔΔCT method. Group differences assessed by t-test. Data shown as mean±SEM. Results: Upon visual inspection, the aged APVAT appeared more visibly brown relative to young. Histological analysis revealed that old mice exhibited a lower APVAT lipid area (young: 67.25±1.05%; old: 48.3±4.04%; p=0.0063), and greater APVAT specific aortic collagen content (Young 1±0 Arbitrary Units (AU); Old: 1.905±0.7AU; p=0.004) relative to young. Old mice also exhibited greater Ucp1, Lipe (hormone sensitive lipase), and Adrb3 gene expression compared to young, all genes that are highly expressed in brown adipose tissue. Ex vivo mechanical testing of the old aorta revealed leaving the APVAT intact (2247±297.4AUC) resulted in greater intrinsic stiffness compared to a cleaned aorta (1761±277.5AUC; p=0.04). Conclusion: The Aged APVAT exhibits a browner, but fibrotic APVAT phenotype and contributes to greater intrinsic aortic stiffness. Funding: NIH 1261603280 (Trott) This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.