PEROXISOMES IN MICE FED A DIET SUPPLEMENTED WITH LOW-DOSES OF FISH-OIL

The influence of low dietary doses (0.1 and 0.8% w/w) Oi a commercial fish oil preparation on peroxisomes in normal mice was studied and com pared to the known strong inductive effects of high (10%) fish oil die ts. Low fish oil doses were chosen to supply the mice with a concentra tion of docosahexaenoic acid, which was beneficial to patients with a peroxisomal disease. Peroxisomes were evaluated by cytochemical, morph ometric, and enzymological techniques. The 0.1% fish oil diet had no e ffect on peroxisomes in liver, heart, and kidney even after prolonged treatment. The 0.8% diet did not change the peroxisomal number nor the catalase (EC 1.11.1.6) activity in the liver. Hepatic peroxisomal bet a-oxidation, however, was increased by 50% after 14 d. This was accomp anied by reduced peroxisomal size. The 0.8% diet also caused a small i ncrease (+25%) in myocardial catalase activity. No effect was observed in kidneys. Our results indicate that in mice a low (<0.8%) dietary f ish oil dose has no or only a slight effect on hepatic per oxisomal be ta-oxidation. This may be of particular interest to patients with a pe roxisomal fatty acid beta-oxidation defect and who display a severe de ficiency of docosahexaenoic acid-diets supplemented with low fish oil doses will improve the docosahexaenoic acid level without adding a str ong load to the disturbed fatty acid metabolism.