Comparison of the Effect of Fish Oil and Corn Oil on Chemical-Induced Hepatic Enzyme-Altered Foci in Rats

• Published in: Journal of agricultural and food chemistry 2000-09, Vol.48 (9), p.4144-4150
• Main Authors: Ko, Yuh-Jane, Lii, Chong-Kuei, Ou, Chu-Chyn, Liu, Jer-Yuh, Lin, Wea-Lung, Chen, Haw-Wen
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Carcinogenesis, carcinogens and anticarcinogens; Corn Oil - pharmacology; Female; Fish Oils - pharmacology; Foods and miscellaneous; gamma-Glutamyltransferase - metabolism; Glutathione Transferase - metabolism; Liver - drug effects; Liver - enzymology; Liver Neoplasms, Experimental - enzymology; Liver Neoplasms, Experimental - pathology; Liver Neoplasms, Experimental - prevention & control; Medical sciences; Precancerous Conditions - enzymology; Precancerous Conditions - pathology; Pregnancy; Rats; Rats, Sprague-Dawley; Tumors
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf0000631

The effects of fish oil and corn oil diets on diethylnitrosamine initiation/phenobarbital promotion of hepatic enzyme-altered foci in female Sprague−Dawley rats were investigated. Groups of 12 rats were initiated with diethylnitrosamine (15 mg/kg) at 24 h of age. After weaning, they received diets containing either 13.5% fish oil plus 1.5% corn oil or 15% corn oil for 24 weeks. Rats fed fish oil had significantly greater liver weight, relative liver weight, spleen weight, and relative spleen weight than rats fed corn oil (p < 0.05). Hepatic phospholipid fatty-acid profile was significantly affected by the type of dietary lipid. The rats fed fish oil had significantly greater hepatic phospholipid 20:5 and 22:6 than rats fed corn oil; in contrast, the rats fed corn oil had significantly greater hepatic phospholipid 18:2 and 20:4 than rats fed fish oil (p < 0.05). Rats fed fish oil had significantly lower hepatic vitamin E and PGE2 content but significantly greater hepatic lipid peroxidation than rats fed corn oil (p < 0.05). The hepatic levels of antioxidant enzymes (GSH reductase and GST) were significantly greater in rats fed fish oil than in rats fed corn oil (p < 0.05). Except for PGST-positive foci (foci area/tissue area), all the other foci parameters (GGT-positive foci area/tissue area, GGT-positive foci no./cm2, GGT-positive foci no./cm3, PGST-positive foci no./cm2, and PGST-positive foci no./cm3) measured in the fish oil group were 10−30% of those in the corn oil group (p < 0.05). Analyses of Pearson correlation coefficient revealed a positive correlation between hepatic GGT- or PGST-positive foci number (no./cm2) and PGE2 content (r = 0.66, P = 0.01; r = 0.56, P = 0.02, respectively) but a negative correlation between GGT- and PGST-positive foci (no./cm2) and lipid peroxidation (r = −0.8, P = 0.0006; r = −0.58, P = 0.01, respectively), GSH/(GSH + GSSG) ratio (r = −0.61, P = 0.05; r = −0.4, P = 0.14, respectively), GSH reductase (r = −0.75, P = 0.002; r = −0.53, P = 0.02, respectively), and GST activities (r = −0.65, P = 0.01; r = −0.44, P = 0.07, respectively). Similar correlation between foci number (no./cm3) and PGE2, lipid peroxidation, GSH/(GSH + GSSG) ratio, GSH reductase, and GST activities were obtained. The results of this study show that dietary fish oil significantly inhibited hepatic enzyme-altered foci formation compared with corn oil in rats. These results suggest that the possible mechanisms involved in this process are the stimulatio