Abstract 12069: Brown Adipose Specific Genes UCP-1 and Cidea Are Highly Expressed in Murine Perivascular Adipose Tissue
Introduction: Perivascular adipose tissue (PVAT) is a unique adipose depot with characteristics of both brown and white adipose. It is not known whether PVAT contains true brown adipose tissue (BAT) or “brite” adipocytes; white adipose tissue that can be induced to express UCP−1. Cidea, a gene encoding a BAT specific lipid droplet protein, is not robustly expressed in “brite” adipocytes.
Hypothesis: We tested the hypothesis that Cidea expression is lower in PVAT than in true BAT, and that expression of this gene might be influenced by a high fat diet (HFD).
Methods: C57BL/6 (n=12) mice were fed normal diet (ND) or a HFD for 13 weeks. Mice were weighed, fasting plasma glucose was measured, and then animals were then sacrificed and adipose tissue was harvested from the aortic arch (PVAT), subcutaneous (SC), visceral (VF), and BAT. Tissues were fixed for microscopy or frozen for RNA extraction. cDNA was synthesized and QPCR was performed. Results were quanitated with the 2-ΔΔct method and expressed relative to the SC fat of ND controls.
Results: HFD mice were more obese (45.5 ± 1.3 vs. 31.6 ± 11.1, p<0.001) and had greater fasting plasma glucose (222 ± 13.4 vs. 168 ± 11.1, p<0.05) than ND controls. In ND animals, expression of PPARγ2 was higher in PVAT than in SC (3.0 ± 0.55 vs. 1.0 ± 0.64, p<0.01); in HFD animals there was no difference (Figure 1). Cidea (120.42 ± 41.0 vs 0.79 ± 0.08, p<0.03) and UCP-1(2433 ± 821.12 vs. 2.7 ± 1.3, p<0.03) were markedly increased in PVAT compared to SC. Interestingly, there was no difference in Cidea and UCP-1 expression between PVAT and BAT. There was a non-significant trend for reduced Cidea expression in PVAT with HFD. Electron microscopy of PVAT revealed both white and brown adipocytes.
Conclusions: Cidea and UCP-1 are highly expressed in PVAT, to levels equivalent to BAT. There is a trend for a reduction in expression of Cidea with HFD. We conclude that PVAT contains true brown adipose tissue which may be influenced by high fat diet.
- © 2010 by American Heart Association, Inc.