The control of lipogenesis by dietary linoleic acid and its influence on the deposition of fat.

The replacement of dietary starch by sucrose results in an increase in hepatic lipogenesis in the rat. When corn oil (4% by weight or 9% of the energy content of the diet) was included with the sucrose (20% by weight, 20% of the energy content) the lipogenic effect of the sucrose was completely suppressed. In contrast, when beef tallow replaced the corn oil, the induced activity caused by the sucrose was reduced by only approximately 20%. No significant differences were observed between males and females. These diets containing sucrose supplemented with either 4% (w/w) corn oil or 4% (w/w) beef tallow, were then used to ascertain whether or not the effects on hepatic lipogenesis were reflected in changes in the amount of fat deposited during growth from 4--24 weeks of age. It was shown that the percentage body fat was only statistically different (P less than 0.05) when animals fed sucrose-supplemented diets were compared with animals fed diets supplemented with sucrose and beef tallow. However, there were no significant differences in total carcass weight of these rats. The results are discussed in terms of the relative contribution of liver and adipose tissue to total lipogenesis and the factors which control the lipogenic activity in the two tissues.