Incorporation of 1-14C-acetate into lipids of liver slices from rats fed threonine imbalanced diet

It has been generally accepted that stimulation of hepatic lipogenesis is largely responsible for fatty infiltration in the liver of rats fed a low casein diet supplemented with 0.3% methionine (threonine imbalanced diet). The present study was undertaken to reexamine if the increased lipogenesis could virtually be a sole factor for production of this type of fatty liver. Lipogenesis by liver slices from 1-14C-acetate during the course of lipid accumulation was compared between rats fed a low-protein diet (control group) and those fed the imbalanced diet. 1) The accumulation of liver triglyceride due to feeding the imbalanced diet was already demonstrated after 3 days. No significant difference was observed in liver phospholipid. 2) The incorporation of 1-14C-acetate into hepatic total lipids did not significantly increased in all of rats fed the imbalanced diet for 1 to 14 days. However, the relative distribution of radioactivity in triglyceride tended to increase in the imbalanced group. 3) The specific activity of triglyceride tended to increase after feeding the imbalanced diet for 1 day, but it was not significant. No differences could be observed after 3 and 7 days. 4) The ratio of the incorporation into monoenoic to saturated fatty acids tended to increase in the rats fed the imbalanced diet for 6 days. These results did not support the view that the increased hepatic lipogenesis would be the major cause for the production of this type of fatty liver. (auth.)