High-cholesterol diet enriched with onion affects endothelium-dependent relaxation and NADPH oxidase activity in mesenteric microvessels from Wistar rats.

Diana González-Peña,Susana Vallejo,Carlos F Sánchez-Ferrer,Concepción Sánchez-Moreno,Concepción Peiró,Clara Colina-Coca,Begoña De Ancos,Javier Angulo

doi:10.1186/1743-7075-11-57

Abstract

BackgroundThe aim of the present study was to examine the effects of onion as functional ingredient on the oxidative status, lipoprotein levels (total cholesterol-TC, HDL-C, LDL-C), triacylglycerides (TAG) and vascular reactivity of mesenteric arteries in hypercholesterolemic Wistar rats.MethodsTwenty-four animals were fed with three different diets [control, high-cholesterol diet (HC) and high-cholesterol enriched with onion diet (HCO)]. After seven weeks of experimental feeding the rats were euthanized for blood and tissues collection. TC, HDL-C, LDL-C and TAG were measured, and 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) radical cation (ABTS•+) scavenging capacity and ferric reducing antioxidant power (FRAP) were determined in plasma. Superoxide dismutase (SOD) and glutathione peroxidase (GPx) enzyme activities were assayed in erythrocyte lysates. Endothelium-dependent vasodilation to acetylcholine was evaluated in mesenteric arterial segments. NADPH oxidase (NOX) was also measured by lucigenin-derived chemiluminiscence.ResultsThe dietary cholesterol content significantly affected plasma lipoprotein levels, increased superoxide generation from NOX, and caused impaired endothelium-dependent vasodilation in the rat mesenteric arteries. Onion ingredient improved antioxidant status in HCO group, as it was evidenced by ABTS•+ and FRAP values and SOD and GPx enzyme activities compared to the HC-fed group, reduced the increment in NOX activity and reversed endothelial dysfunction promoted by the HC diet. Scavenging of superoxide with TEMPOL or inhibition of NOX with apocynin improved endothelium-dependent vasodilation only in HC-fed rats.ConclusionsEnrichment of diet with onion as functional ingredient could be proposed as a complementary approach to prevent or partially modulate vascular dysfunction, reducing some of the risk indexes linked to initial development of atherosclerosis.

Highlights

The aim of the present study was to examine the effects of onion as functional ingredient on the oxidative status, lipoprotein levels, triacylglycerides (TAG) and vascular reactivity of mesenteric arteries in hypercholesterolemic Wistar rats
Food intake and body weight gain The food intake (g/day) of the rats did not differ among the groups during the feeding period (16.14 ± 0.20 for control, 15.99 ± 0.18 for high-cholesterol diet (HC), and 16.33 ± 0.26 for high-cholesterol enriched with onion diet (HCO))
As the growth curve shows (Figure 1), there was no significant difference in the body weight gain (g) among the three groups after the feeding period (141.80 ± 9.75 for control, 133.68 ± 6.93 for HC, and 132.00 ± 9.36 for HCO)

Summary

Introduction

The aim of the present study was to examine the effects of onion as functional ingredient on the oxidative status, lipoprotein levels (total cholesterol-TC, HDL-C, LDL-C), triacylglycerides (TAG) and vascular reactivity of mesenteric arteries in hypercholesterolemic Wistar rats. Dietary intake of certain nutrients has been suggested as an alternative in the prevention of several pathologies, as a gentle mean of modifying the mechanisms involved in the progression of cardiovascular disease [5,6,7,8,9] Recent evidences in this line have pointed out the consumption of flavonoid-rich food such as wine and grape related products, chocolate and soya in the improvement of different endothelial functions [10,11,12], the consumption of the well-known rich in antioxidants Mediterranean diet in the amelioration of endothelial vasodilation in hypercholesterolemic subjects [13] and the decrease in the incidence of major cardiovascular events in persons with cardiovascular risk [14]

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