Role of Perivascular Adipose Tissue in Aorta Reactivity from Obese and Hyperglycemic CD-1 Mice: New Insights into Perivascular Adipose Tissue.

Background: Perivascular adipose tissue (PVAT) plays an essential role in cardiovascular homeostasis. However, during obesity and diabetes, its role in vascular tone regulation is unclear. This study aimed to evaluate the function of the PVAT on aorta reactivity in the lean and cafeteria (CAF) diet-induced obese-hyperglycemic mice model. Methods: Aorta reactivity to phenylephrine, KCl, and acetylcholine was analyzed in lean (n = 6) and obese mice (n = 6). Also, nitric oxide (NO-) and cyclooxygenase participation, in the presence (n = 6) and absence (n = 6) of PVAT, were examined in the aortas. Results: After a CAF diet for 19 weeks, obese mice showed increased body weight, glucose intolerance, and hypercholesterolemia concerning lean mice. Vascular reactivity to phenylephrine was reduced significantly in the aorta of obese mice. In contrast, the contraction produced by KCl (80 mM) was increased in the aorta of obese mice independent of PVAT. Acetylcholine-induced vasorelaxation diminished in the aortas of obese mice in the presence of PVAT. Nonselective inhibition of cyclooxygenases likely shows that PVAT and endothelium release vasorelaxant prostanoids. Conclusions: The results suggest that PVAT modulates aorta reactivity by releasing NO-, decreasing the α1-adrenergic response to phenylephrine, and probably releasing vasorelaxant prostanoids. The data suggest that PVAT regulates the vascular smooth muscle and endothelial function in a CAF diet-induced obese-hyperglycemic mice model.

Vascular endothelial function is improved by oral glycine treatment in aged rats.

Glycine has been used to reduce oxidative stress and proinflammatory mediators in some metabolic disorders; however, its effect on the vasculature has been poorly studied. The aim of this work was to explore the effect of glycine on endothelial dysfunction in aged rats. Aortic rings with intact or denuded endothelium were obtained from untreated or glycine-treated male Sprague-Dawley rats at 5 and 15 months of age. Concentration-response curves to phenylephrine (PHE) were obtained from aortic rings incubated with N(G)-nitro-l-arginine methyl ester (l-NAME), superoxide dismutase (SOD), indomethacin, SC-560, and NS-398. Aortic mRNA expression of endothelial nitric oxide synthase (eNOS), NADPH oxidase 4 (NOX-4), cyclooxygenase 1 (COX-1), cyclooxygenase 2 (COX-2), tumour necrosis factor (TNF)-α, and interleukin-1 ß was measured by real time RT-PCR. The endothelial modulation of the contraction by PHE was decreased in aortic rings from aged rats. Glycine treatment improved this modulator effect and increased relaxation to acetylcholine. Glycine augmented the sensitivity for PHE in the presence of l-NAME and SOD. It also reduced the contraction by incubation with indomethacin, SC-560, and NS-398. Glycine increased the mRNA expression of eNOS and decreased the expression of COX-2 and TNF-α. Glycine improved the endothelium function in aged rats possibly by enhancing eNOS expression and reducing the role of superoxide anion and contractile prostanoids that increase the nitric oxide bioavailability.