Maternal Separation Enhances Anti-contractile Perivascular Adipose Tissue Function in Male Rats on a High Fat Diet.

Clinical studies have shown that obesity negatively impacts large arteries' function. We reported that rats exposed to maternal separation (MatSep), a model of early life stress, display enhanced angiotensin II (ANG II)-induced vasoconstriction in aortic rings cleaned of perivascular adipose tissue (PVAT) under normal diet (ND) conditions. We hypothesized that exposure to MatSep promotes a greater loss of PVAT-mediated protective effects on vascular function and loss of blood pressure (BP) rhythm in rats fed a high-fat diet (HFD) when compared with controls. MatSep was performed in male Wistar-Kyoto rats from days 2 to 14 of life. Normally reared littermates served as controls. On ND, aortic rings from MatSep rats with PVAT removed showed increased ANG II-mediated vasoconstriction versus controls; however, rings from MatSep rats with intact PVAT displayed blunted constriction. This effect was exacerbated by an HFD in both groups; however, the anticontractile effect of PVAT was greater in MatSep rats. Acetylcholine-induced relaxation was similar in MatSep and control rats fed an ND, regardless of the presence of PVAT. HFD impaired aortic relaxation in rings without PVAT from MatSep rats, whereas the presence of PVAT improved relaxation in both groups. On an HFD, immunolocalization of vascular smooth muscle-derived ANG-(1-7) and PVAT-derived adiponectin abundances were increased in MatSep. In rats fed an HFD, 24-h BP and BP rhythms were similar between groups. In summary, MatSep enhanced the ability of PVAT to blunt the heightened ANG II-induced vasoconstriction and endothelial dysfunction in rats fed an HFD. This protective effect may be mediated via the upregulation of vasoprotective factors within the adipovascular axis.