Abstract
Obesity, a condition of excessive fat mass and subclinical inflammation, reached epidemic proportions with higher prevalence in women compared to men worldwide. Expansion of the perivascular adipose tissue (PVAT) is observed in obesity and clinical studies indicate a positive correlation between PVAT amount and body mass index. PVAT, a fat depot surrounding most of the vessels, modulates vascular function by releasing PVAT-derived factors such as adipokines that exert anticontractile effect in health individuals. Despite sexual dimorphism on PVAT morphology, it is still unknown whether or not there is sex differences in the PVAT modulating vascular function in the setting of obesity. Aldosterone-mineralocorticoid receptor (MR) signaling pathway has been demonstrated to be adipogenic and proinflammatory in classical fat depots and treatment with MR antagonists (A) might reverse vascular dysfunction and remodeling in obese models, especially in female sex. Therefore, we aimed to evaluate the anticontractile effect of PVAT in male and female obese mice and hypothesized that MR signaling would be involved in possible sex differences in PVAT dysfunction in obesity. Male and female C57Bl6/J mice were fed a chow or a high-fat diet (HFD, 60% energy from fat) for 20 weeks. At the last 4 weeks of HFD, female and male mice were treated with the MRA spironolactone (Spi, 100 mg/kg/day). HFD feeding significantly increased body weight and visceral adipose tissue, which was not modified by Spi treatment in both sexes. Resistance mesenteric arteries were isolated with or without PVAT and mounted in a wire myograph to evaluate vascular contractile responses. Lean male and female mice PVAT had an anticontractile effect in the response to phenylephrine that was greater in females than males. The anticontractile effect of PVAT was significantly impaired in obese females but not modified in males. HFD-induced dysfunctional PVAT was prevented by Spi treatment in females. Next, we evaluated the protein expression of aldosterone-synthase CYP11B2, serum and glucocorticoid-regulated kinase 1 (SGK1), and epithelial sodium channel subunits (ENaCs) in isolated mesenteric PVAT of lean and obese male and female mice. There was an increased expression of CYP11B2, SGK1 and ENaCs only in obese female PVAT. Protein expression of adiponectin, a major PVAT-released adipokine was also increased in female mesenteric PVAT. In conclusion, the findings suggest sexual dimorphism in PVAT function in health and in obesity. Although anticontractile role of PVAT was exacerbated in lean female mice, female sex was more susceptible to develop PVAT dysfunction in the setting of obesity which was prevented by MR blockade. HFD-induced PVAT dysfunction in females was associated with increased expression of SGK1 and ENaCs. Therefore, data suggest MR activation as a mechanism mediating sex differences in PVAT dysfunction.
FAPESP, CAPES.
SUN-LB93 Mineralocorticoid Receptor Mediates Sex-Dependent Anticontractile Effect of Perivascular Adipose Tissue in Obese Mice
