DIETARY DOCOSAHEXAENOIC ACID HAS LITTLE EFFECT ON PEROXISOMES IN HEALTHY MICE

NMRI mice were fed diets supplemented with 0.05, 0.2, or 2% (w/w) doco sahexaenoic acid (DHA), a polyunsaturated fatty acid present in fish o il, for 3 d, 3 wk, or 3 mon. The doses of DHA were chosen to supply th e mice with concentrations of DHA which approximate those that have be en reported to be beneficial to patients with peroxisomal disease. Die ts containing 0.05 or 0.2% DHA did not change hepatic, myocardial, and renal catalase (EC 1.11.1.6) activity except for a slight but signifi cant increase (to 120%) in myocardial catalase activity in mice treate d with the 0.05% DHA diet for 3 mon. A diet with 2% DHA induced myocar dia[ catalase activity to 150% after both 3 d and 3 wk of administrati on. In the liver of mice fed this diet for 3 wk, hepatic catalase acti vity was increased to 140% while no induction of palmitoyl-CoA oxidase (EC 1.3.99.3), urate oxidase (EC 1.7.3.3), and L-alpha-hydroxyisovale rate oxidase (EC 1.1.3.a) was observed. With the light microscope, no changes in peroxisomal morphology were visually evaluated in catalase stained sections of liver, myocardium, and kidney of mice fed either d iet. Our results show that in healthy mice a low dietary DHA dose (<0. 2%; this corresponds to a dose prescribed to peroxisomal patients) has no effect on several hepatic peroxisomal H2O2-producing enzymes, incl uding the rate-limiting enzyme of the peroxisomal fatty acid P-oxidati on. This may indicate that such a DHA dose will not add a strong load on the often disturbed fatty acid metabolism in the liver of patients with peroxisomal disorders.