Iron intake affects lipid peroxidation and glutathione peroxidase activity of distal colonic mucosa

Abstract

The purpose of this study was to examine the effect of low, adequate, and high dietary iron (Fe) levels on lipid peroxidation, glutathione S-transferase (GST) and glutathione peroxidase (GSH-Px) activities, and glutathione (GSH) concentrations in colon and liver. Male Sprague Dawley rats were fed iron deficient (DFe; 14 mg Fe/kg diet; n=8), adequate iron (AFe; 39 mg Fe/kg diet, n=8), or high iron (HFe; 454 mg Fe/kg diet; n=8) diets for 3 weeks. Liver Fe concentrations were 26, 84, and 243 ug/g wet weight, respectively, for rats fed DFe, AFe, and HFe diets (p<0.0001). Lipid peroxidation was increased 70% in distal colonic mucosa of rats fed HFe diets compared to that of rats fed AFe and DFe diets (p<0.01), but lipid peroxidation was unaffected by diet in proximal colon or liver. While distal colonic mucosal GSH-Px activity was lower in DFe rats (0.062 U/mg protein), than in AFe rats (0.091 U/mg protein), and HFe rats (0.089 U/mg protein) (p<0.05), iron intake had no effect on GSH-Px activity in proximal colon or liver. The distal colon had higher GSH-Px activity than proximal colon (p<0.0001). GST activity in colon and liver, and hepatic GSH concentrations were not altered by dietary iron intakes. This study suggests that distal and proximal colonic mucosa may respond differently to changes in Fe status.