MODULATION OF PLASMA AND HEPATIC OXIDATIVE STATUS AND CHANGES IN PLASMA-LIPID PROFILE BY N-3 (EPA AND DHA), N-6 (CORN-OIL) AND A 3-THIA FATTY-ACID IN RATS

This manuscript describes changes in plasma lipid profiles and paramet ers of oxidative status in the plasma and liver of rats fed 5 differen t fatty acids: 95% eicosapentaenoic acid, 92% docosahexaenoic acid (DH A), corn oil (n-6), 1-mono-(carboxymethylthio)-tetradecane (CMTTD) and palmitic acid (controls) for 3 months. At the given doses both EPA an d the 3-thia fatty acid, CMTTD, caused a significant decrease in plasm a triglycerides, phospholipids, free fatty acids and cholesterol. DHA decreased plasma free fatty acids and cholesterol, while corn oil feed ing reduced only plasma free fatty acids. Plasma and hepatic vitamin E levels were significantly decreased in EPA, DHA and CMTTD fed rats, b ut remained unchanged in corn oil fed rats. Plasma glutathione was not ed to decrease after EPA and DHA feeding but remained unchanged in oth er groups. However, hepatic glutathione content was increased in EPA, DHA and CMTTD fed rats, whereas cysteine levels were noted to decrease . As hepatic levels of cysteinylglycine remained unchanged, increased rate of cellular glutathione synthesis rather than its decreased degra dation is likely to contribute to the increased hepatic glutathione co ntent in EPA, DHA and CMTTD fed rats. Except for reduction in the leve ls of plasma lipid peroxidation caused by CMTTD, no significant change s were noted between the different treatment groups. Hepatic lipid per oxidation was elevated only in rats given DHA. Furthermore, our result s show that EPA and DHA cause minimal imbalance of the peroxisomal H2O 2 metabolising enzymes as compared to CMTTD. In addition, contrary to the potent peroxisome proliferator compound CMTTD which decreased the activities of glutathione transferase and glutathione peroxidase, EPA and DHA increased the activities of these detoxification enzymes.