Effect of dietary kelp on lipid peroxidation and glutathione peroxidase activity in livers of rats given breast carcinogen DMBA.

In our previous study of female rats, a diet containing 2% of powdered fronds of Laminaria religiosa (kelp) had a remarkable inhibitory effect on mammary tumorigenesis induced by orally given 7,12-dimethylbenz[a]anthracene (DMBA). In this study, the effect of the dietary kelp on lipid peroxidation and glutathione peroxidase (GSH-Px) activity in the liver was studied in the same experimental system. Two separate short- and long-term experiments were carried out on rats fed a diet with 2% kelp. DMBA (20 mg/kg body wt) was given to each animal 7 days after feeding began in short-term experiment and 27 days later in long-term experiment. Livers of all rats were obtained for quantitative determination and for histopathologic observation. Lipoperoxide in livers of the kelp-fed rats was of normal value, almost the same as that of untreated control rats; however, lipoperoxide in livers of control rats was significantly higher than in the other two groups in both experiments. A marked fatty change in livers of control rats was demonstrated in hepatic cells in peripheral zones of lobules in long-term experiment but not in short-term experiment. In long-term experiment, the amounts of GSH-Px and selenium in livers of kelp-fed rats were slightly less than those in untreated control rats but more than those in control rats. There was a more-intense positive reaction in the hepatic cells in the peripheral zones of the lobules in the kelp-fed and untreated rats and a less-intense positive reaction in control rats.(ABSTRACT TRUNCATED AT 250 WORDS)