Seiichi Hayakawa

Effect of age of the modification of brain polyunsaturated fatty acids and enzyme activities by fish oil diet in rats

To determine the effect of age on the modification of brain lipids and functions by fish oil and lard diets, the polyunsaturated fatty acids, phospholipid states and enzyme activities of intracellular organelles in young and aged rats fed these diets were analyzed. The concentration of arachidonic acid (20:4) and docosahexaenoic acid (22:6) tended to decrease with increasing age. The UV absorption of phosphatidylethanolamine (PE) and phosphatidylcholine (PC) also decreased. An increasing effect of the sardine oil diet on brain 22:6 concentration in aged rats was slightly greater than that in young rats. However, the modification of 20:4 concentration in aged rats was similar to that in young rats. Significant increases in the UV absorption of PE and PC of aged rats fed the fish oil diet were observed. The lactate dehydrogenase (LDH) activities of aged rats fed the sardine oil diet increased significantly, whereas the activities of aged rats fed the lard diet decreased. These results suggest that fish oil may be able to regulate the brain lipid composition and LDH activity in aged rats.

Effect of age on the modification of rat plasma lipids by fish and soybean oil diets

The effects of sardine and soybean oils on plasma lipids have been studied in young and aged rats. Plasma cholesterol and bile acids of aged rats fed on a sardine oil diet decreased to a greater degree than those of young rats. Cholesterol, bile acids and phospholipids of the soybean oil diet group decreased only in aged rats. Increases in plasma eicosapentaenoic (sardine) and linoleic (soybean) acid levels of aged rats were observed to be greater than those of young rats. These results indicate that the age enhances the effects of fish and soybean oils on plasma lipids by suppressing their characteristic fatty acid metabolism.

Effect of coix on plasma, liver, and fecal lipid components in the rat fed on lard- or soybean oil-cholesterol diet.

To determine the influence of dietary coix on lipid metabolism, the effect of coix on plasma, liver, and fecal lipid components was studied using Sprague-Dawley male rats. All rats were divided into four groups, and the rats of each group were fed the coix-lard diet, coix-soybean oil diet, or the respective control diets (containing 1% cholesterol each) for 27 days. Plasma and liver cholesterol levels in the coix-lard diet group significantly decreased as compared with those in the control group, whereas there was no effect on the fecal excretion of cholesterol. The decreases in the concentrated liver triglyceride and the increases in the fecal excretion of triglyceride were found in coix-soybean oil diet group. Moreover, liver and fecal phospholipid levels in both coix diet groups significantly increased. But there were no significant changes in plasma and fecal bile acids in either coix diet group. These results suggest the possibilities that coix may have an inhibitory action on cholesterol synthesis in liver, a facilitating effect on biliary excretion of triglyceride, and an acceleratory action on phospholipid synthesis in liver.

Effect of age on plasma bile acids and lipid components in the rat

With increasing age, total plasma bile acid contents increased in rats over a period of 11 months, and also total plasma cholesterol and carcass fat contents increased in the same manner. Plasma showing high bile acid levels at 11 months was found by means of high performance liquid chromatography to contain cholic acid as one of the major components, chenodeoxycholic acid and trace deoxycholic acid. These results suggest that there are close relationships between the plasma bile acids and age-dependent changes of lipid components in the rat.

Age-associated changes in rat plasma lipids, platelet fatty acids and prostacyclin release

The effect of age on plasma lipids, platelet fatty acids and prostacyclin release was studied in the rat. The contents of arachidonic acid, cholesterol, bile acids and free fatty acids in the plasma of aged rats (15 months old) were higher than those of young rats (3 months old). No significant differences in fatty acid composition of platelet lipids and release of prostacyclin from aortas between young and aged rats were observed. The data suggest that plasma lipids may play a more important role in the development of cardiovascular disease with increasing age than prostaglandins do.