Divergent Phenotype of Rat Thoracic and Abdominal Perivascular Adipose Tissues

Abstract

Perivascular adipose tissue (PVAT) is implicated as a source of pro‐atherogenic adipokines. It is possible that phenotypic differences in local PVAT depots may contribute to differences in disease susceptibility among arteries and even regions within an artery. In this regard, it has been proposed that PVAT around the abdominal and thoracic aorta share characteristics of white and brown AT, respectively; however, a detailed comparison between these PVAT depots has not been performed. Using young (3 months) and older (13 months) adult rats, we compared the phenotype of PVATs surrounding the abdominal and thoracic aorta to each other and also to epididymal white and subscapular brown ATs. We found that expression of inflammatory genes and markers of immune cell infiltration were greater in abdominal PVAT than in thoracic PVAT, and that overall, abdominal and thoracic PVATs resembled the phenotype of white and brown ATs, respectively. Immunohistochemistry and electron microscopy indicated structural similarity between white and abdominal PVAT and between brown and thoracic PVAT. Our data provide evidence that abdominal PVAT is more inflamed than thoracic PVAT independent of aging. Interestingly, these phenotypic differences in PVAT depots associate with known differences in disease susceptibility of the underlying aortic regions. Support: AHA 11POST5080002, T32‐AR048523, R01‐HL036088.