Effects of dietary fat and 1,2-dimethylhydrazine on microsomal lipid peroxidation.
1994
Kuratko C.N. | Tsai S.Y. | Pence B.C.
An increased intake of polyunsaturated fatty acids, especially those of the omega-3 series, has shown beneficial effects in prevention of chronic diseases, including cancer. It is not known if at high levels, incorporation of these fatty acids into membrane phospholipids will cause adverse effects due to increased tissue susceptibility to peroxidation. This study was designed to determine whether diets high in polyunsaturated fatty acids would increase liver and colon susceptibility to peroxidation. Secondly, the study examined the effect of diet and the colon carcinogen, 1,2-dimethylhydrazine, on potential peroxidation in these tissues. Rats were fed diets of varied fatty acid composition and effects were compared over time and as the result of injection of 1,2-dimethylhydrazine. Test diets consisted of a low fat corn oil diet or high fat diets of either corn oil, beef tallow, or menhaden oil. Fatty acid composition of colon microsomes was determined. Lipid peroxidation products were measured as thiobarbituric acid-reacting substances in liver and colon microsomes before and after induction with iron/ADP/ascorbate. Content of polyunsaturated fatty acids in colon microsomes was shown to vary according to diet. Induced peroxidation of liver microsomes was highest in the menhaden oil group but only in young animals. Older animals showed greater levels of induced peroxidation in the liver and less effect of diet. Dimethylhydrazine increased inducible peroxidation in the liver without a clear pattern of difference by diet. Tissue differences were also apparent. Colon microsomes showed resistance to peroxide induction by iron/ADP/ascorbate and no difference in peroxide content as the result of DMH. Increases in lipid peroxidation do not appear to be associated with this model of colon carcinogenesis.
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