Effect of saturated fat diets on rat liver NADP-linked enzymes

¹ Department of Pharmacology, State University of New York, Upstate Medical Center, Syracuse, New York

The aggregate hexosemonophosphate dehydrogenase (HMPD) activity was found to be higher in livers of rats fed a diet containing saturated fat (hydrogenated coconut oil = H) for 7 days and fasted for 48 hr than it was in similarly prepared animals fed a corn oil (CO) diet. Later, a liver HMPD-increasing effect of feeding H was found in nonfasted animals. Lipogenesis (i.e., the incorporation of acetate-1-C¹⁴ into fatty acids by liver slices) was shown to be as low or lower in the H group as in the CO. Liver slices prepared from H and CO diet adapted rats were incubated with either acetate-1-C¹⁴ or palmitate-1-C¹⁴ and the extent of incorporation of C¹⁴ into individual fatty acids was measured. With both substrates more radioactivity was found in 16:1, 18:0, and 18:1 in the case of H-fed animals. It is proposed that a component of the signal for eliciting increased NADP-linked enzyme activity in the H rats was an increased rate of oxidation of NADPH attendant on monoene formation and chain lengthening.

Note:
With the Technical Assistance of Janet Pownall and Andrew Branch

Key Words: hexosemonophosphate dehydrogenase • glucose 6-phosphate dehydrogenase • 6-phosphogluconate dehydrogenase • malic enzyme • NADPH oxidase • monoenoic fatty acid synthesis • essential fatty acid deficiency • refeeding lipogenesis • adaptive enzyme formation • pyridine nucleotide coenzymes

Submitted on March 4, 1965