Insulin response to glucose-6-phosphate dehydrogenase activity is elevated in rats fed diets low in polyunsaturated fatty acids.

Glucose-6-phosphate dehydrogenase (G6PD) activity in the rat liver was elevated when the animals were fed a diet that contained 5% coconut oil or 1% corn oil plus 4% palmitic acid, in comparison with that of rats fed 5% corn oil. G6PD activity correlated inversely with the PUFA/SFA ratio of total liver phospholipid as well as the ratio of plasma membrane phospholipid. Elevation of G6PD activity was slightly affected by dietary protein. Serum insulin levels were apparently not influenced by dietary fats, and were not correlated with G6PD activity. Insulin dose-response to G6PD activity was augmented in primary cultured hepatocytes isolated from rats fed a diet with 1% corn oil plus 4% palmitic acid in comparison with those fed a diet with 1% corn oil plus 4% palmitic acid in comparison with those fed a diet with 5% corn oil. These findings indicate that augment in insulin dose-response to G6PD and elevation of its activity shown in rats fed diets low in polyunsaturated fatty acid are associated with lowering the PUFA/SFA ratio in plasma membrane phospholipid.