Aortae of Young Rats with Metabolic Syndrome Exhibit Enhanced Vasoconstrictor Activity Than Older Rats

Abstract

Background Metabolic syndrome (MetS) causes pathological remodeling of the heart and adjacent vessels. The functional changes in the big vessels in different age groups had not been fully delineated. Aim of the work The present study was planned to investigate aortic vasodilator and vasoconstrictor reactivity in young, adult and old female rats with MetS. Design: The experimental study was performed on 90 female albino rats randomized into 6 groups: young, adult and old rats with MetS and their respective control groups. Methods MetS was induced by feeding rats 41% fructose -containing diet and giving fructose solution (5 g fructose in 4 ml distilled water/day) by gavage in two sessions (2 ml/session). On the 8th week, all rats were sacrificed and were subjected to determination of body weight (BW), body mass index (BMI), absolute and relative visceral fat weight (VF), fasting blood glucose (FBG), plasma insulin (PI), homeostasis model of insulin resistance (HOMA-IR) and plasma lipid profile. All rats’ aortae were subjected to study of vascular reactivity to Potassium chloride (KCL), phenylephrine (PE) and acetyl choline (A.Ch) as well as estimation of nitrite content. Results On the 8th week of the study, all MetS groups developed criteria of metabolic syndrome as evidenced by the significant increase in final BW, BMI, absolute and relative VF weights, FBG, PI and HOMA-IR compared to their control group values. Also, MetS rat groups exhibited evident dyslipidemia in the form of significant increase in plasma levels of triglycerides, total cholesterol and significant decrease in HDL-cholesterol compared to their control group values. Aortae of young and adult MetS rat groups showed significant increase in their vasoconstrictor response to KCl and PE and decrease in A.Ch/KCL% and A.Ch/PE % compared to their controls, while old MetS rat group showed significantly increased vasoconstrictor response only to KCL compared to their controls. When compared to each other, young age MetS group had significantly higher vasoconstrictor response to PE compared to old MetS group despite comparable nitrite content. Conclusion Met.S causes functional vascular changes in all age groups with unexpectedly enhanced vasoconstrictor response in the young group compared to old.