Goldthioglucose肥満マウスにおける脂酸代謝に関する研究 第2編 (U)-14C-palmitic acid, 1-14C-linoleic acidおよび1-14C-γ-linolenic acidの脂酸代謝について

Fatty acids synthesis from acetate in goldthioglucose obese (GTG) mice was described in part Ⅰ. In this report, the incorporation of (14)C from (U)-(14)C-palmitic acid, 1-(14)C-linoleic acid and 1-(14)C-γlinolenic acid into individual fatty acids and major lipid classes of liver was determined in vivo. Results were as follows. 1) No significant differences between GTG and control mice were found in the incorporation of (14)C into saponifiable fraction of lipids (total fatty acids) from (14)C-palmitic acid, (14)C-linoleic acid and (14)C-γ-linolenic acid. 2) In the percentage distribution of (14)C in malor lipid classes in both groups of mice, it was found that (14)C come from (14)C-palmitic acid was incorporated mainly into triglyceride, (14)C from (14)C-linoleic acid into triglyceride and phospholipids, and (14)C from (14)C-γ-linolenic acid. mainly into phospholipids. A few differences between. GTG and control mice were found in the percentage distribution of (14)C from (14)C-palmltic acid, (14)C-linoleic acid and (14)C-γ-linolenic acid in triglyceride and phospholipids. 3) In regard to the study on the incorporation of (14)C into individual fatty acids of saponifiable fraction of lipids, the percentage of (14)C recovered in palmitic acid from (14)C-palmitic acid more increased and that in stearic acid more decreased in GTG mice than in control mice. When (14)C-linoleic acid was used as precursor the percentage of (14)C recovered in linoleic acid was 55-62% and that in arachidonic acid was about 12% of 14C in total fatty acids, in both groups of mice. However, the percentage distribution of (14)C in γ-linolenic acid from (14)C-γ-linolenic acid was 10% and that in arachidonic acid was 46-58% , in both groups of mice. The rate of conversion from γ-linolenic acid to arachidonic acid more increased in GTG mice than control mice. 4) In regard to the esterification of individual fatty acids into major lipid classes, it was found in both groups of mice that linoleic acid was more esterified into tryglyceride than into phospholipids, and arachidonic acid was esterified mainly into phospholipids. From these results, metabolism of palmitic acid and essential fatty acids in GTG mice is characterized by increased palmitic acid pool and increased ratio of the conversion from γ-linolenic acid to arachidonic acid.