Perivascular Adipose Tissue Media Explant Impairs the ex‐vivo Endothelial Function in Obese Mice Exposed to Early Life Stress via the Mineralocorticoid Receptor signaling

Abstract

Perivascular adipose tissue (PVAT) is no longer exclusively linked to energy storage; it releases hormonal factors that may influence vascular function and other metabolic processes. Maternal Separation and Early Weaning (MSEW) is a mouse model that mimics the effect of early life stress on cardiovascular and metabolic systems and increases the risk of obesity, hypertension, and eventually, cardiovascular disease. We have previously shown that female MSEW mice present exacerbated obesogenic response to chronic high fat diet (HFD), showing a metabolic syndrome-like phenotype and associated hypertension. Additionally, female obese MSEW mice display an increase in plasma aldosterone and gonadal White Adipose Tissue (gWAT) mineralocorticoid receptor (MR) expression. Therefore, this study aimed to test the influence of PVAT-derived factors on the endothelial function of female MSEW mice fed a HFD, treated chronically with a vehicle or an MR antagonist. Female C57BL/6J mice pups were separated from their dams Postnatal Day (PD) 2 to 16 and weaned early on PD 17. Control litters remained unhandled with their dams and were weaned on PD 21. After weaning, Control and MSEW mice were placed on HFD (60% Kcal from fat) for 16 weeks. Then, mice were euthanized, thoracic aortas were isolated and cleaned for vascular reactivity studies, and PVAT was collected in DMEM (2% BSA, 2-hour incubation, 37C). Cumulative concentration response (CCR) curves were performed for acetylcholine (Ach, 10-5 to 10-9 M) and sodium nitroprusside (SNP, 1x10-6 to 1x10-14 M) after pre-constriction with serotonin (2×10-3 M, 5 ul). Experiments were performed in mice treated with vehicle (50% Ora Swift in drinking water) or spironolactone (100 mg/kg/day, two weeks). A first CCR curve was performed after isolated rings were incubated with DMEM, followed by a second CCR curve following a PVAT media explant incubation. In isolated rings of vehicle-treated mice incubated with DMEM, Ach-induced Vascular relaxation was similar in control and MSEW mice (50.15±4.7 vs. 49.8±1.6 % Relaxation, respectively). However, PVAT preincubation impaired vascular relaxation in MSEW mice compared to controls (37.3±3.4 vs. 49.6±1.3 % Relaxation, p<0.05). Overall, spironolactone-treated mice showed improved vascular relaxation in isolated rings of MSEW and control mice (57.8±3.5 vs. 64.1±1.4 % Relaxation). Furthermore, Spironolactone enhanced the endothelial function in rings from MSEW mice pre-incubated with PVAT media explant compared to controls (57.18±5.1 vs. 57.20±4.8 % Relaxation). No differences in SNP-induced relaxation were found between groups. Treatment with an MR antagonist restores the endothelial function in female MSEW mice fed a HFD. These findings suggest that PVAT-derived factors from female mice exposed to MSEW have a detrimental effect on the vascular function mediated by MR signaling. Further investigation is needed to pinpoint the role of PVAT on the mechanism contributing to the worsening of the vascular function via the MR signaling in obese female mice exposed to early life stress.