[Effects of experimental Listeria monocytogenes infection on mice fed on lamprey or sardine oil prepared under high-temperature deodorization].

Fresh lamprey (F-La) or sardine (F-Sa) oil is known to contain a large amount of n-3 polyunsaturated fatty acids such as eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids. When F-La or F-Sa was deodorized with steam at 280 degrees C under 1 mmHg for 1 h (H-La and H-Sa, respectively), the contents of EPA and DHA were reduced and unidentified peaks were newly detected by gas-liquid chromatography. To know the biological influences of these high-temperature deodorized oils, the sterilizing function of the macrophage against Listeria monocytogenes was investigated in male ddY mice fed H-La or H-Sa. One week feeding of H-La or H-Sa lowered the LD50 values of the bacteria injected intravenously. Numbers of the viable bacteria on the day 3 after intravenous injection were about 10 times higher in the liver and 5 times higher in the spleen of mice fed H-La or H-Sa as compared with those of the control group. These results suggest that the sterilizing function of fixed macrophages both in the liver and the spleen was suppressed in mice fed H-La or H-Sa.