The stimulatory effect of fermented vegetable product (FVP) upon the phagocytic and superoxide generation of leukocytes was studied in the Japanese flounder Paralichthys olivaceus . The phagocytic activity of casein-induced, intraperitoneal leukocytes was investigated and quantified, that is the activity significantly increased ( P < 0.05 or < 0.01) by the addition of FVP beyond 3 mg/kg body weight. Further analysis investigated the effect of FVP on superoxide generation in leukocytes. Established in vitro cytochrome c reduction assay was used to measure superoxide generation; reduced levels of FVP in assay samples had a profound effect on superoxide generation. FVP was also incorporated in commercial diets and fed to Japanese flounder for 4 weeks. The phagocytic activities and superoxide generation of peritoneal induced leukocytes were significantly higher ( P < 0.05, < 0.01) in fish fed the FVP supplemented diet than fish fed the control diet. FVP feeding in fish had a significantly higher ( P < 0.05) activity of lysozyme than in the control fish.KEY WORDS: fermented vegetable product, immunostimulation, Japanese flounder, nonspecific immunity.

We investigated the protective effects of a fermented vegetable product (FVP) against the hemolysis and lipid peroxidation of Japanese flounder (Paralichthys olivaceus) erythrocytes in vitro. 2,2′‐Azobis (2‐aminopropane) dihydrochloride (AAPH) and tert‐butyl hydroperoxide were used as model compounds that cause oxidative stress through the generation of free radicals and induction of lipid peroxidation, respectively, in erythrocytes. The hemolysis and lipid peroxidation of erythrocytes induced with 125 mM AAPH and 25 mM tert‐butyl hydroperoxide, respectively, were suppressed by the administration of 1–2 mg/mL FVP (P < 0.01). These results suggested that the FVP reduces oxidative stress in fish and may be useful for the rearing of cultured fish.

To study the dietary effects of fermented vegetable product (FVP) on the protection against lipid peroxidation of various tissues in Japanese flounder, Paralichthys olivaceus. The fish were fed on experimental diets with or without FVP for 4 weeks. The glutathione concentrations in serum or liver had a tendency to increase on FVP-feeding fish. The FVP-feeding fish showed higher glutathione peroxidase (GPx) activity of liver than the control fish, and the GPx activity was increased by the administration of 6 mg/kg body weight/day FVP (P < 0.05). Conversely, fish fed on FVP containing diets exhibited significantly (P < 0.05) lower lipid peroxidants of serum and liver than the control fish. The FVP is suggested to suppress lipid peroxidation in the administrated fish, which led to enhancement of antioxidant effect against cultured fish.

SummaryWe examined the effects of a fermented vegetable product (FVP) , fermented by yeast as well as lactic acid bacteria, on body weight and fat deposition after ovariectomy in 10-wk-old Sprague-Dawley rats. The rats were divided into the following 5 groups: l) ovari ectomized rats fed as usual (OVX); 2) ones receiving FVP at a daily dose of 100mg/kg (LOW); 3) ones receiving FVP at a daily dose of 1,000mg/kg (HIGH); 4) ones receiving a calcium-free diet (Ca-FREE); 5) sham-operated rats (SHAM) . A slight increase in body weight was observed in the LOW group compared with the OVA group . The rate of increase in total fat content was lowest in the LOW group, but both bone weight and strength were similar to those in the other ovariectomized groups. In conclusion , the low dose of FVP turned out to reduce fat content without affecting bone weight and strength .

We studied the effects of oral administration of immunostimulants (curdlan and quillaja saponin) and formalin-killed Edwardsiella tarda cells (FKC) on the protection against edwardsiellosis in Japanese flounder Paralichthys olivaceus. Fish were fed experimental diets containing im munostimulants and FKC singly or in combination for three weeks. The survival rates were observed for 19 days after challenge with E. tarda, and the agglutination titers against the bacterium were meas ured before and after the challenge. Fish fed the immunostimulants showed higher survival rates than the control group, with the agglutination titers being as low as those of the control group. On the other hand, fish fed on FKC-containing diets exhibited significantly (p<0.05) higher survival rates and titers than the control group. The immunostimulants were suggested to activate immune systems in the vacci nated fish, which led to enhancement of resistance against edwardsiellosis.