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Mice, at weaning, were placed on a diet supplemented with beef tallow (BT), linoleic acid (18: 2n-6)-rich safflower oil (SO), alpha-linolenic acid (18: 3n-3)-rich perilla oil (PO) or docosahexaenoic acid (22: 6n-3, DHA)-rich fish oil (FO) to modify membrane fatty acid vulnerability to peroxidation, then carbon tetrachloride (CCl4) was administered chronically. CCl4-induced liver injury, estimated using serum alanine aminotransferase activity and liver hydroxyproline content, was not different among the 4 dietary groups; however, the FO diet lowered the liver triacylglycerol (TG) level when compared with the BT and SO diets. The FO diet group exhibited a significantly higher level of thiobarbituric acid-reactive substances (TBARS) in the liver when compared with the three other dietary groups. Chronic CCl4 treatment decreased the proportion of eicosanoid precursors (arachidonate and eicosapentaenoate) rather than that of DHA, with the highest peroxidizability among major fatty acids in liver, and did not enhance TBARS formation in any of the dietary groups. The protein carbonyl content in the liver was similar among the 4 dietary groups but was decreased following CCl4 treatment. Liver alpha-tocopherol contents were affected both by diet and CCl4 treatment, and a positive correlation was observed between alpha-tocopherol and TG contents. These results indicate that increasing the autoxidizability of dietary fatty acids or the chronic CCl4 treatment did not synergistically enhance liver injury or the accumulation of oxidation products in mice.

The fatty acid composition of rat polymorphonuclear leukocytes (PMN) was modified by diets supplemented with a high linoleate (LA) safflower oil (76% LA), mixtures of eicosapentaenoate (EPA) and safflower oil (EPA(20) containing 20% EPA and 61% LA, EPA(40) containing 40% EPA and 46% LA), mixtures of docosahexaenoate (DHA) and safflower oil (DHA(20) containing 20% DHA and 61% LA, DHA(40) containing 40% DHA and 46% LA) or a high alpha-linolenate (alpha-LNA) perilla oil (57% alpha-LNA and 13% LA), and then lipid mediator production in casein-induced peritoneal PMN were compared. EPA and DHA were relatively ineffective in reducing platelet-activating factor (PAF) production; a statistically significant reduction was observed only in the DHA(40) group. In contrast, perilla oil reduced PAF production by 50% as compared with safflower oil. Arachidonate (AA) in the PAF precursor, 1-alkyl-2-acyl-glycerophosphocholine, was roughly correlated with PAF production, but EPA and DHA in the precursor lipid were relatively unrelated. On the other hand, both PGE2 and LTB4 production correlated positively with AA and negatively with EPA and DHA in PMN phospholipids; EPA tended to be somewhat more effective than DHA in reducing PGE2 and LTB4 formation; the activity of perilla oil was no less than EPA(20). Thus, replacing safflower oil with perilla oil was no less effective than supplementing safflower oil with EPA or DHA (at 40% of total fatty acids) in reducing lipid mediator production in rat PMN.

Low-fat conventional diets supplemented with 5 or 10% vegetable oils were fed to stroke-prone spontaneously hypertensive rats (SHR-SP) from weaning and the mean survival times were determined. A 1% aqueous sodium chloride solution was used as drinking water throughout the experiments. In four separate experiments, the rapeseed oil group showed a significantly shorter mean survival time. The relative mean survival times were 50-59% (rapeseed oil group), 78-100% (soybean oil group) and 86% (microbial oil group) as compared with the group fed perilla oil (100%). The group which received 4-fold diluted rapeseed oil exhibited a significantly shorter survival time as compared with the group receiving soybean oil. Although the feeding experiments were performed under very simple and restricted conditions, these results suggest that the rapeseed oil prepared for human use contains a factor (s) which is toxic to SHR-SP rats.

Previously, we noted significant differences in the behavioral patterns of mice fed safflower oil with a very low alpha-linolenate/linoleate ratio and perilla oil with a high alpha-linolenate/linoleate ratio from mothers to offsprings. In this report, we compared the behavior and drug responses in mice fed diets containing six different vegetable oils-corn, rapeseed, soybean, safflower, perilla and a mixture of perilla and safflower oils- for a relatively short period: 8 months after weaning. Soybean oil is a component of most conventional diets and was used as a control. The alpha-linolenate/linoleate ratios of the oils appeared to affect the locomotor activities in a wheel cage: the activity decreased in the order of safflower, the mixture (1:1) and the perilla oil groups. However, the rapeseed oil group exhibited much higher locomotor activity than that expected from the alpha-linolenate/linoleate ratio. Additionally, the rapeseed oil group exhibited unusual behavior patterns, including higher ambulation and rearing activities, faster acquisition of the water maze task and slower habituation behavior as compared with the control group. Susceptibility to pentobarbital anesthesia tended to be higher in the rapeseed oil group. The differences in the alpha-linolenate/linoleate ratios of these oils alone do not account for the observed differences in the behavioral patterns among the six dietary groups. Although we cannot exclude the possibility that the observed behavioral anomaly is due to the unique fatty acid composition of rapeseed oil, we speculate that a factor(s) other than fatty acids in rapeseed oil affected nervous system functions.

Aged mice (6 months of age) fed a conventional diet were shifted to diets containing 10% lard, high-linoleate safflower seed oil, high α-linolenate perilla seed oil or high-docosahexaenoate fish oil. A significant increase in whole body cholesterol (/g wt) was seen within 30 d after the shift (rapid response), followed by a gradual decrease in 60 to 120 d (slow response) ; similar changes occurred in all the dietary groups. Shortly after the shift, the serum cholesterol concentrations increased to higher levels in the lard and safflower oil groups than in the other groups, and the levels at 120 d were in the group order of safflower oil>lard>perilla oil>fish oil. Rapid and slow responses to dietary shifts were also seen in hepatic cholesterol levels (/g wt), which were higher in the lard group than in the other groups at 120 d. The arterial cholesterol contents of the fish oil group tended to be less than in the other groups at 120 d. Thus in aged mice after a relatively long-term feeding (>one tenth of the life-span), safflower oil was not hypocholesterolemic as compared with lard and other ω3-rich oils. Long-term feeding of fish oil maintained serum cholesterol concentrations at lower levels than feeding with safflower oil or lard and without accumulating cholesterol in the aorta, liver or whole body ; perilla oil was also hypocholesterolemic but to a lesser degree than fish oil. Saturated, monounsaturated and linoleic acids in diets accumulated relatively efficiently in the whole body but ω3 fatty acids were catabolized preferentially in aged mice. Our results do not support the concept that an increased intake of high-linoleate vegetable oils is useful for the prevention of hypercholesterolemia-associated diseases ; however, dietary oils rich in ω3 fatty acids may be useful.

Anti-allergic drugs, tranilast and azelastine, were examined for their effects on lysophosphatidylserine (lysoPS)-dependent histamine release from rat mast cells. Although both compounds suppressed the histamine release in a dose-dependent manner, the inhibition was affected by lysoPS concentration differently. In the presence of an increasing concentration of lysoPS, the suppressive effect of tranilast decreased. The inhibition by azelastine, however, was independent of the concentration of lysoPS. The findings suggest that these two drugs inhibit lysoPS-dependent histamine release through essentially different routes.