Effect of the administration of fish oil by gavage on activities of antioxidant enzymes of rat lymphoid organs.

1. The effect of administration of fish oil by gavage on catalase (CAT), glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) activities of the lymphoid organs and liver was compared with those of soybean oil and cocoa butter. 2. Fish oil did not affect the activities of SOD and CAT but reduced that of GSH-Px in the spleen. In contrast, cocoa butter reduced the CAT activity in the thymus and liver, and soybean oil decreased CAT activity in the thymus. 3. The content of thiobarbituric acid reactive substances of the lymphoid organs was not modified but was increased in plasma.