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.