Reduction of hepatic stearoyl-CoA desaturase activity in rats fed iron-deficient diets.

The effect of feeding iron-deficient diets to rats on the hepatic stearoyl-CoA desaturase activity was examined since iron is present in the delta 9 desaturation system. Separate groups of rats were fed low iron diets without fat (FF-Fe) or containing either 14% hydrogenated coconut oil (HCNO-Fe) or 14% corn oil (CO-Fe) for 10 weeks. Diets supplemented with iron (FF + Fe, HCNO + Fe and CO + Fe) were fed to the corresponding control groups. Stearoyl-CoA desaturase activity in the liver microsomes of rats in the CO + Fe group (2.55 +/- 0.17 nmol oleate produced/min/mg protein) was about half of that in the HCNO + Fe (4.76 +/- 0.15) and FF + Fe (5.38 +/- 0.18) diet groups. In rats which were fed iron-deficient diets, hepatic desaturase levels were reduced significantly as compared to those of controls (1.0 +/- 0.06, CO-Fe; 2.11 +/- 0.13, HCNO-Fe; 3.65 +/- 0.1, FF-Fe). The hemoglobin (Hb) and hematocrit (Hct) levels in blood showed moderate iron depletion only in the CO-Fe group. Hence, dietary polyunsaturated fat promotes the onset of iron deficiency. Furthermore, even before the blood Hb and Hct values express iron depletion, the effect of feeding low iron diets was observed by the reduction of hepatic delta 9 desaturase activity in rats fed HCNO-Fe and FF-Fe diets.