Effects of Ghrelin on hypertension and insulin resistance in fructose-fed rats

Abstract

To explore the effects and mechanisms of Ghrelin on hypertension and insulin resistance in fructose-fed rats. A total of 32 male Sprague-Dawley (SD) rats were randomized into control (A) and fructose-fed groups (B). Rats in group B were fed with 10% fructose solution for 4 weeks. Then the rats in group A were randomized into intraperitoneal saline (group GA1) or intraperitoneal 50 nmol/kg Ghrelin (group GA2) and those in group B into intraperitoneal saline (group GB1) or intraperitoneal 50 nmol/kg Ghrelin (group GB2) twice daily for 6 weeks. Caudal arterial pressure was measured weekly. Plasma blood glucose, insulin concentration and lipid profile were measured. And insulin resistance (IR) was calculated by the method of homeostasis model assessment (HOMA). Plasma level of 15-F2t-isoprostane was measured by enzyme-linked immunosorbent assay (ELISA). Ghrelin caused a significant reduction of systolic pressure at Week 3 in group GB2 versus group GB1 (P < 0.05). Maximal effect appeared at Week 5 ((127 ± 5) vs (120 ± 6) mm Hg, P < 0.05, 1 mm Hg = 0.133 kPa), but blood pressure failed to reach normal value. Ghrelin also decreased plasma insulin concentration and HOMA-IR ((9.6 ± 2.6) vs (13.1 ± 3.6) µU/ml, P < 0.05;1.92 ± 0.12 vs 2.78 ± 0.14, P < 0.01). Plasma level of 15-F2t-isoprostane was lower in group GB2 than that in group GB1 ((75 ± 11) vs (102 ± 14) pg/ml, P < 0.01). Ghrelin may lower blood pressure, ameliorate insulin resistance and improve insulin sensitivity through inhibiting oxidative stress in fructose-induced rats.