Browsing by Subject "Food -- Fat content -- Physiological aspects"
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Item Effects of dietary fat and dimethylhydrazine on rat colonic antioxidant status: implications for carcinogenesis : a dissertation in home economics(Texas Tech University, 1991-08) Kuratko, Connye J. N.Previous studies have shown that the composition of membrane phospholipids reflects the fatty acid composition of the diet. Membranes that contain a high proportion of polyunsaturated fatty acids (PUFA) are potentially more susceptible to attack by free radicals. Radicals are reactive chemical species that contain one or more unpaired electrons. Oxygen and some of its metabolites are radicals that are highly reactive, potentially toxic to the cell, and have been implicated in a variety of disease processes. Double bonds within PUFA participate in reactions with these radicals and propagate their formation. Cells contain protective antioxidant mechanisms including superoxide dismutase (SOD), glutathione peroxidase (GSHPx), catalase (CAT), glutathione (GSH), glutathione reductase (GSSGRx), glutathione-S-transferase (GST) among others. Cellular damage results as these mechanisms become depleted. The effects of dietary fat on these antioxidant mechanisms in colon mucosa were examined using male Sprague-Dawley rats. Animals were fed one of four AIN 76A-based test diets differing in amount and type of lipid. The basal diet (BD) contained 5% corn oil; the menhaden oil diet (MO) contained 1% corn oil and 19% menhaden oil; the corn oil diet (CO) contained 20% corn oil; and the beef tallow diet (BT) contained 1% corn oil and 19% beef tallow; all were adjusted to provide equal amounts of other nutrients. Homogenates of colon mucosa were assayed after 2 weeks, 1, 3, 6 and 9 months for activities of CAT, GSHPx, SOD, GST, GSSGRx, and total GSH content. In the first objective of this study, measurements were made at the various time points in rats fed test diets to determine whether diets high in polyunsaturated fatty acids (PUFA) would produce an increased demand on antioxidant activity in colon mucosa. Beginning at the 2-week time point GSH, GSSGRx, and SOD showed differences due to diet. At 1 month only GST showed differences. Then, at the 3-month point, GSH, GSSGRx, GSHPx, and at the 6-month point, GST, SOD, GSHPx and CAT, respectively, were affected. By the 9-month time point, only CAT showed differences due to diet. Both the type and amount of fat in the