Regulation of expression and activity of selenoenzymes by different forms and concentrations of selenium in primary cultured chicken hepatocytes

Abstract

The expression and activity of selenoenzymes are regulated by Se. In the present study, the effects of different forms and concentrations of Se on the regulation of glutathione peroxidase (GPx) activity and phospholipid hydroperoxide GPx (GPx4) and type I deiodinase (D1) mRNA levels in chicken hepatocytes were evaluated. Primary cultured chicken hepatocyte monolayers derived from male White Leghorn chickens (aged 30-40d) were incubated for 24h with 0 (control), 05, 1, 15, 2, 3, 4 or 5mol/l of Se supplied as dl-selenomethionine (Se-Met), -selenocarrageenan (Se-Car) or sodium selenite (Na2SeO3). Compared with the control, Se significantly increased GPx activity in all the hepatocytes, but the activity was not increased in the hepatocytes treated with 5mol/l of Na2SeO 3, with maximal effects being observed at 2μmol/l of Se-Met or Se-Car and at 15mol/l of Na2SeO3, respectively. Significant decreases in GPx4 mRNA levels were observed in all the hepatocytes treated with Se (v. control). The D1 mRNA levels were significantly increased in all the groups treated with Se (v. control), with maximal effects being observed at 15mol/l of Se-Met and at 05mol/l of Se-Car or Na2SeO 3, respectively. Se-Met at doses of 15-5μmol/l had a greater effect on D1 mRNA than Se-Car and Na2SeO3 at equivalent doses. After resulting in a maximal effect, higher Se supplementation led to a dose-dependent reduction in GPx activity and D1 mRNA levels in all the hepatocytes treated with Se. These results suggest that in chicken hepatocytes, the regulations of GPx and D1 by different forms and concentrations of Se vary. Copyright © The Authors 2010.