Date of Award:

1989

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Nutrition, Dietetics, and Food Sciences

Department name when degree awarded

Toxicology

Advisor/Chair:

A. Mahoney

Abstract

Effects of Fe and Se status on GSHPx activity and lipid peroxidation in liver and intestinal mucosa were studied. Rats were Se and Fe supplemented ( +Se+Fe), Sedeficient and Fe-supplemented (-Se+Fe), Se supplemented and Fe overloaded (+Se++Fe) by intramuscular injection, or Se deficient and Fe overloaded (-Se++Fe) for 20d. Fe overloaded tissues had more Fe, but hemoglobin was unaffected. Liver and mucosal GSHPx activity was low in Se-deficient rats. Thiobarbituric acid reactive substances (TBARS) were higher in Fe overloaded and -Se++Fe vs +Se++Fe tissues. Mucosal TBARS was higher in -Se++Fe rats gavaged with CBrCl3. In experiment 2, Fe overload was induced by a 2% carbonyl iron, low-Se diet fed for 2mo, the +Se++Fe and -Se++Fe groups. Low Se-, low Fe-diet was fed to rats supplemented with Fe or Fe and Se in the water, the -Se+Fe and +Se+Fe controls. Iron overloaded tissues had more Fe. Liver and mucosal GSHPx activity was lower in Se-deficient and +Se++Fe vs +Se+Fe rats. TBARS was higher in Fe overloaded, -Se++Fe vs +Se++Fe, and CBrCl3 tissues. Hemoglobin and serum Fe were lower in the -Se++Fe group. In experiment 3, low-Se, low-Fe diet was fed for 20d, the -Se-Fe, +Se-Fe, -Se+Fe and +Se+Fe groups. Mucosal Fe was lower in the Fe-deficient rats. Cytochrome P-450 and GSHPx activities were lower and TBARS was higher in Se-deficient tissues. In experiment 4, the +Se+Fe, +SeFe, -Se+Fe, -Se-Fe, +Se++Fe, and -Se++Fe groups treated as in experiment 3. Iron overloaded tissues had more Fe and TBARS, but hemoglobin and serum Fe were unaffected. GSHPx and Cytochrome P-450 activities were lower in Se-deficient and in +Se++Fe vs +Se+Fe rats. CBrCl3 did not affect TBARS.

High TBARS occurred in liver and mucosa of Fe overloaded rats. Chronic Fe overload was required to reduce liver and mucosal GSHPx activity. The combination of Se deficiency and Fe overload caused very high TBARS. Low oral CBrCl3 doses elevated mucosal TBARS, a first report of extrahepatic action of CBrCl3 in vivo. Iron deficiency did not affect GSHPx activity or CBrCl3 induced lipid peroxidation.

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