Supranutritional dietary selenium induced hyperinsulinemia and dyslipidemia via affected expression of selenoprotein genes and insulin signal-related genes in broiler

Abstract

The purpose of this study was to investigate the effects of supranutritional selenium (Se) on the mRNA expression of selenoprotein genes and insulin signal-related genes in the liver, muscle and pancreas of the broiler. A total of 160 one-day-old Cobb male broilers (n = 80 per group) were fed a Se-deficient corn–soybean basal diet supplemented with 0.3 (adequate), and 3.0 (excess) mg kg⁻¹ sodium selenite for 6 weeks. Pancreas, liver and muscle were collected, and the effects of supranutritional Se on mRNA abundance of 23 selenoprotein genes and 17 insulin-related genes were compared at day 42. Also, enzyme activities and plasma biochemical measurements were measured at days 14, 28, and 42. The results showed that a high-Se diet depressed the growth performance of broilers and elevated (P < 0.05) the activities of superoxidase dismutase (SOD), total antioxidant capacity (T-AOC) and glutathione peroxidase (GSH-Px), mainly in the early stages. A high-Se diet up-regulated 12 selenoprotein genes in muscle, 7 genes in liver and Sephs2 in the pancreas, and down-regulated 3 selenoprotein genes in muscle, 4 genes in liver and 7 genes in the pancreas. Meanwhile, 4, 3 and 2 insulin signal-related genes were up-regulated in muscle, liver and the pancreas, respectively, 3 and 5 genes were down-regulated in muscle and the pancreas. Accompany the aberrant expression of selenoprotein and insulin signal-related genes, the birds exhibited a higher plasma insulin, total triglyceride (TG) and total cholesterol (TC) concentrations by high Se. In conclusion, the high Se diet induced hyperinsulinemia and dyslipidemia in birds via a mediating aberrant expression of selenoprotein genes associated with insulin signal-related genes, which indicated potential roles of those selenoprotein genes in the lipid and carbohydrate metabolism regulation in birds.