Neuropeptide Y (NPY) receptor 2 deletion in adipocytes blunts fat‐derived aldosterone production in female mice exposed to chronic stress

Abstract

NPY is a 36‐amino acid peptide that plays a critical role in the regulation of energy homeostasis. In response to chronic environmental stress, NPY released by neurons innervating the fat promotes adipocyte proliferation and lipid storage via NPY receptor 2 (Y2). Y2 also stimulates aldosterone synthesis in the adrenal gland; however, little is known about its role in the regulation of aldosterone secretion in adipose tissue. We have previously shown that Maternal Separation and Early Weaning (MSEW), a mouse model of early life stress, exacerbates high fat diet (HF)‐induced adiposity and increases circulating aldosterone in female mice but not in males. Thus, the aim of this study was to investigate the effect of MSEW on chronic stress‐induced aldosterone release by adipose tissue with or without the deletion of Y2. In addition, we tested the capacity of adipose tissue conditioned media from these mice to modulate the endothelial function of aortic rings ex‐vivo. Y2‐WT and Y2‐KO pups were separated from the dam for 4 to 8 hours during postnatal days (PD) 2 to 16 and weaned on PD 17. Control mice remained undisturbed and were weaned on PD 21. At weaning, female mice were fed a HF (60% Kcal from fat) for 16 weeks. Following, a subset of mice were subjected to restraint stress (RS) for 6 more consecutive weeks and the other one was not disturbed (NORS). At the end of the experiment, mice were euthanized, and ~50 mg of fresh adipose tissue was incubated in DMEM + 2% fatty acid free BSA (1 hour, 37°C). Aldosterone concentration was measured in media explants by ELISA. Visceral adipose tissue‐derived aldosterone secretion was similar in WT MSEW and control explants from NORS mice (3.22±0.21 vs 3.50±0.76 pg/mg tissue). RS increased aldosterone levels in the media explant from MSEW mice compared to controls (5.34±0.85 vs. 2.96±0.35 pg/mg tissue). The deletion of Y2 from adipose tissue depots attenuated the increased aldosterone release in response to RS in MSEW mice only (5.34±0.85 to 3.46±0.21 pg/mg tissue; p < 0.05). In additional studies, we used perivascular adipose tissue (PVAT) and mesenteric adipose tissue (MESAT) media explants from RS control and MSEW mice to test their effect on acetylcholine (Ach)‐dependent relaxation (pre‐constricted with ser 10−3 M, 3 ul). We performed relaxation dose‐response curves in thoracic aortic rings from healthy female mice (16‐week‐old fed a regular chow) before and after the incubation with fat explants. We found similar worsening of the baseline vascular relaxation when we incubated rings with PVAT media from MSEW and controls (14.38±4.58 vs. 19.95±3.80 Delta % relaxation). However, rings incubated with MESAT from MSEW mice showed significant worsening of the vascular relaxation compared to controls (26.71±4.44 vs. 12.43±2.63 Delta % relaxation, p<0.05). Y2 deletion protected the vascular function in both groups. Taken together, female MSEW mice exposed to RS are prone to release aldosterone from adipose tissue, dependent upon Y2 signaling. Increased aldosterone release near vessels may explain impaired endothelial function, which could be prevented by targeting adipose tissue Y2.Support or Funding InformationR01 HL135158