Dietary oxidized frying oil enhances tissue alpha-tocopherol depletion and radioisotope tracer excretion in vitamin E-deficient rats.
Rats fed a diet containing 15% oxidized frying soybean oil (OFO) have been shown to have significantly lower tissue alpha-tocopherol (alpha-T) concentration than rats fed a 15% fresh soybean oil diet. To examine the turnover of alpha-tocopherol, a depletion-repletion experiment and a radioisotope tracer study were conducted. Two groups of male weanling Long-Evans rats were fed vitamin E-deficient diets containing either 15% OFO or 15% vitamin E-stripped fresh soybean oil (control). After 9 wk of depletion, rats fed the OFO diet had significantly higher plasma pyruvate kinase (PK) activity and lower concentrations of alpha-T in RBC, adrenal gland, heart, kidney, liver, spleen, testis and muscle compared with controls (P < 0.05), indicating that the vitamin E-deficient status was aggravated by feeding the OFO diet. After 12 wk, the depleted rats were intraperitoneally injected with a dose of all-rac-alpha-T (2.5 mg/rat, dissolved in Vitamin E-stripped corn oil) every other day. Three doses were administered to each rat during the 1-wk repletion period. Plasma PK activity decreased in both groups (P < 0.05) after repletion but that of the OFO rats was still significantly higher than that of the control group. The repleted OFO gorup also had significantly lower alpha-T concentration in adrenal gland, epididymal fat, liver and spleen than the repleted control group. Two rats from each group that had been vitamin E-depleted for 16 wk were injected intraperitoneally with a single dose of 5-methyl-14C-RRR-alpha-T (740 kBq/kg body weight). During the week after dosing, the radioactivity excreted in urine and feces of the OFO group was 1.3- and 1.7-fold, respectively, that of the control group. Tissue retention of radioactivity was also lower in the OFO rats than in the control rats. The results suggest that more of the alpha-T in the body was catabolized or turned over in rats fed the OFO-containing diet.
Liu
J F
JF
Department of Agricultural Chemistry, National Taiwan University, Taipei, Republic of China.
Huang
C J
CJ
D000311:Adrenal Glands / Q000737:chemistry; D000818:Animals; D002250:Carbon Radioisotopes; D004042:Dietary Fats, Unsaturated / Q000378:metabolism / Q000494:pharmacology*; D004435:Eating / Q000502:physiology; D004912:Erythrocytes / Q000737:chemistry; D006128:Growth / Q000502:physiology; D007668:Kidney / Q000737:chemistry; D008099:Liver / Q000737:chemistry; D008297:Male; D018482:Muscle, Skeletal / Q000737:chemistry; D009206:Myocardium / Q000737:chemistry; D010084:Oxidation-Reduction; D011770:Pyruvate Kinase / Q000097:blood; D051381:Rats; D013024:Soybean Oil / Q000378:metabolism / Q000494:pharmacology*; D013154:Spleen / Q000737:chemistry; D013737:Testis / Q000737:chemistry; D014810:Vitamin E / Q000032:analysis / Q000378:metabolism* / Q000494:pharmacology; D014811:Vitamin E Deficiency / Q000503:physiopathology / Q000652:urine*; D015430:Weight Gain / Q000502:physiology
D002250:Carbon Radioisotopes; D004042:Dietary Fats, Unsaturated; D014810:Vitamin E; D013024:Soybean Oil; D011770:Pyruvate Kinase