Early Life Stress Enhances the Obesogenic Response in Female Mice Via Mineralocorticoid Receptor (MR) signaling

Abstract

Adipose tissue homeostasis is a complex processes influenced by many mechanisms that become dysregulated with obesity. We have previously shown that Maternal Separation and Early Weaning (MSEW), a mouse model of early life stress, exacerbates high fat diet (HF)-induced fat deposition in female mice, but not male mice. In addition we have shown that female MSEW mice fed a HF show increased mineralocorticoid receptor (MR) expression in gonadal white adipose tissue (gWAT), which has been shown to promote adipose tissue differentiation. Therefore, the aim of this study was to determine the effect of MSEW combined with chronic HF on gWAT hypertrophy, the tissue source and circulating levels of aldosterone, and whether the pharmacological antagonism of the MR will prevent the exacerbated gWAT expansion in female MSEW mice. MSEW and control (C) mice were weaned onto HF (60 % Kcal from fat) for 20 weeks. Adipose tissue was collected from a small subset of mice to conduct collagenase digestion followed by magnetic activated cell sorting (MACS) for isolation of preadipocytes for RNAseq analysis (Novegene, Bejing, China). Another subset of MSEW and C mice were randomized to receive either vehicle (50% Ora swift in drinking water) or spironolactone (100 mg/kg/day in vehicle) treatment for 2 weeks. RNAseq analysis revealed an upregulation of genes involved in lipoprotein particle binding and protein-lipid complex binding (Pcsk9/Trem2/Lpl/Stab2/Ldlr, P<0.05), and low-density lipoprotein particle binding (Pcsk9/Trem2/Stab2/Ldlr, P<0.05). Female MSEW mice fed a HF for 20 weeks showed increased adiposity compared to C (42.81 ± 1.62 vs. 33.50±0.97 % body weight, respectively, P<0.05). Furthermore, the MSEW females fed a HF displayed increased gWAT whitening determined by reduced mitochondrial DNA density (0.8±0.09 vs. 1.08±0.07 MitoDNA/gDNA, P<0.05). Female MSEW mice fed a HF showed increased aldosterone levels compared to C counterparts (733.12 ± 89.22 vs. 475.95 ± 36.50 pg/mL respectively, P<0.05). Adrenal-derived media explant Aldo was increased in obese female MSEW mice compared with C (83.55±10.44 vs. 38.31±7.65 pg/mg tissue, P<0.05) while it was similar in media from gWAT explants. Chronic MR antagonism induced a greater fat mass loss in female MSEW mice compared to both vehicle-treated MSEW females (-2.07±0.88 vs. 3.11±1.48 treatment delta adiposity, P<0.05) and spironolactone-treated C (-2.07±0.88 vs. 0.62±1.30 treatment delta adiposity, P=0.06). Overall, MSEW-induced exacerbated adiposity was associated with decreased mitochondrial DNA, increased pro-obesogenic gene expression, and increased serum aldosterone. Chronic MR antagonism reduced fat mass in female MSEW mice, suggesting that MSEW might enhance adipose tissue differentiation via MR activation and as well as increased LPL-induced lipid uptake, a MR downstream effector gene. Taken together, these data show that MSEW exacerbates the adrenal gland-derived aldosterone production, whereas the increased gWAT MR expression may contribute to adipocyte hypertrophy.