Periaortic adipose tissue surrounding thoracic versus abdominal aortas of LF- and HF-fed mice (4 months) was analyzed for mRNA abundance by real-time PCR. A, mRNA abundance in periaortic adipose tissue surrounding thoracic aortas from LF and HF-fed mice. B, mRNA abundance in periaortic adipose tissue surrounding abdominal aortas of LF and HF-fed mice. F4/80 mRNA abundance increased to a greater extent in periaortic adipose tissue surrounding abdominal than thoracic aortas. Similarly, obesity-induced elevations in mRNA abundance of CCL2, CCR2, and leptin were greater in adipose tissue surrounding abdominal than thoracic aortas. mRNA abundance of UCP-1 was increased by obesity in thoracic periaortic adipose tissue, but decreased in abdominal. Data are mean ± SEM from n = 5 mice/group. *, P < 0.05 compared to LF.