Contents lists available at ScienceDirect Experimental Gerontology journal homepage: www.elsevier.com/locate/expgero Study of insulin vascular sensitivity in aortic rings and endothelial cells from aged rats subjected to caloric restriction: Role of perivascular adipose tissue S. Amor a , B. Martín-Carro a , C. Rubio b , J.M. Carrascosa b , W. Hu c , Y. Huang c , A.L. García-Villalón a , M. Granado a,d,⁎ a Departamento de Fisiología, Facultad de Medicina, Universidad Autónoma de Madrid, Spain b Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias, Universidad Autónoma de Madrid, Spain c School of Biomedical Sciences, Institute of Vascular Medicine, Faculty of Medicine, Chinese University of Hong Kong, China d CIBER Fisiopatología de la Obesidad y Nutrición, Instituto de Salud Carlos III, Madrid, Spain ARTICLE INFO Keywords: Aging Insulin Akt Perivascular adipose tissue Aorta eNOS ABSTRACT The prevalence of metabolic syndrome is dramatically increasing among elderly population. Metabolic syn- drome in aged individuals is associated with hyperinsulinemia and insulin resistance both in metabolic tissues and in the cardiovascular system, with this fact being associated with the cardiometabolic alterations associated to this condition. Caloric restriction (CR) improves insulin sensitivity and is one of the dietetic strategies most commonly used to enlarge life and to prevent aging induced cardiovascular alterations. The aim of this study was to analyze the possible beneficial effects of CR in aging-induced vascular insulin resistance both in aortic rings and in primary culture of endothelial cells. In addition, the inflammatory profile of perivascular adipose tissue (PVAT) and its possible role in the impairment of vascular insulin sensitivity associated with aging was also assessed. Three experimental groups of male Wistar rats were used: 3 (3 m), 24 (24 m) fed ad libitum and 24 months old rats subjected to 20% CR during their three last months of life (24 m–CR). Aorta rings surrounded or not by PVAT were mounted in an organ bath and precontracted with phenylephrine (10 -7.5 M). Changes in isometric tension were recorded in response to cumulative insulin concentrations (10 -8 –10 -5.5 M) in the presence or absence of L-NAME (10 -4 M). Aortic rings and primary aortic endothelial cells were incubated in presence/absence of insulin (10 -7 M) and the activation of the PI3K/Akt and MAPK pathways as well as nitrite and nitrates concentrations and the mRNA levels of eNOS, insulin receptor, and GLUT-4 were assessed. CR prevented the aging-induced decrease in the vasodilator response to insulin and the aging-induced increase in the vasoconstrictor response to high insulin concentrations. Changes between 24 m and 24 m–CR aorta rings were abolished in the presence of L-NAME. CR induced-improvement in insulin vascular sensitivity was related with activation of the PI3K/Akt both in aortic rings and in aortic endothelial cells in response to insulin. CR attenuated the overexpression of iNOS, TNF-α and IL-1β in the PVAT of aged rats although aortic rings sur- rounded by PVAT from 24 m rats showed and increased vasorelaxation in response to insulin compared to aortic rings from 3 m and 24 m–CR rats. In conclusion, a moderate protocol of CR improves insulin vascular sensitivity and prevents the aging induced overexpression of pro-inflammatory cytokines in PVAT. 1. Introduction Aging is the major risk factor for cardiovascular diseases, as nearly 90% of incident CV events occur in adults over 55 years of age (Gu and Xu, 2013). Aging is associated with several cardiovascular alterations such as endothelial dysfunction and arterial stiffness that lead to an impairment on cardiovascular function (Tuomilehto, 2004). Some of these alterations are linked to metabolic syndrome whose prevalence is increased among elderly men and women. Indeed, the ratio for metabolic syndrome among men and women of 65 years old of age and older is approximately fivefold higher than among those aged 20–34 years old (Park et al., 2003; Schulman et al., 2007). A large body of evidence demonstrates that aging and metabolic syndrome share several metabolic alterations that include an altered distribution, expansion, and endocrine function of adipose tissue (Bonomini et al., 2015; Haffner, 2000), as well as hyperinsulinaemia and insulin resistance (Armani et al., 2017). Indeed, the onset of insulin resistance and type 2 diabetes is a hallmark of aging (Lopez-Lluch and http://dx.doi.org/10.1016/j.exger.2017.10.017 Received 4 August 2017; Received in revised form 15 October 2017; Accepted 16 October 2017 ⁎ Corresponding author at: Department of Physiology, Faculty of Medicine, Universidad Autónoma de Madrid, C/Arzobispo Morcillo no. 2, 28029 Madrid, Spain. E-mail address: miriam.granado@uam.es (M. Granado). Experimental Gerontology xxx (xxxx) xxx–xxx 0531-5565/ © 2017 Elsevier Inc. All rights reserved. Please cite this article as: Amor, S., Experimental Gerontology (2017), http://dx.doi.org/10.1016/j.exger.2017.10.017