Relationship of lipogenic enzyme activities to the rate of rat liver fatty acid synthesis

Conference · Thu May 01 04:00:00 EDT 1986 · Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States)

OSTI ID:5125718

Nelson, G; Kelley, D; Schmidt, P; Virk, S; Serrato, C

The mechanism by which diet regulates liver lipogenesis is unclear. Here the authors report how dietary alterations effect the activities of key enzymes of fatty acid (FA) synthesis. Male Sprague-Dawley rats, 400-500 g, were fasted for 48h and then refed a fat-free, high carbohydrate (HC) diet (75% cal. from sucrose) for 0,3,9,24 and 48h, or refed a HC diet for 48h, then fed a high-fat (HF) diet (44% cal. from corn oil) for 3,9,24 and 48h. The FA synthesis rate and the activities of acetyl CoA carboxylase (AC), fatty acid synthase (FAS), ATP citrate lyase (CL), and glucose 6-phosphate dehydrogenase (G6PDH) were determined in the livers. FA synthesis was assayed with /sup 3/H/sub 2/O, enzyme activities were measured spectrophotometrically except for AC which was assayed with /sup 14/C-bicarbonate. There was no change in the activity of AC during fasting or on the HC diet. Fasting decreased the rate of FA synthesis by 25% and the activities of FAS and CL by 50%; refeeding the HC diet induced parallel changes in FA synthesis and the activities of FAS, CL, and G6PDH. After 9h on the HF diet, FA synthesis had decreased sharply, AC activity increased significantly while no changes were detected in the other activities. Subsequently FA synthesis did not change while the activities of the enzymes decreased slowly. These enzymes did not appear to regulate FA synthesis during inhibition of lipogenesis, but FAS, CL or G6PDH may be rate limiting in the induction phase. Other key factors may regulate FA synthesis during dietary alterations.

• Research Organization: Dept. of Agriculture, Presidio of San Francisco, CA
• OSTI ID: 5125718
• Report Number(s): CONF-8606151-
• Conference Information: Journal Name: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States) Journal Volume: 45:6
• Country of Publication: United States
• Language: English

Related Subjects

550501* -- Metabolism-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ANIMALS
BODY
CARBON 14 COMPOUNDS
CARBON-CARBON LYASES
CARBOXY-LYASES
CARBOXYLASE
CARBOXYLIC ACIDS
DIET
DIGESTIVE SYSTEM
ENZYME ACTIVITY
ENZYMES
FASTING
GLANDS
HYDROGEN COMPOUNDS
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
LIVER
LYASES
MAMMALS
METABOLISM
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANS
OXIDOREDUCTASES
OXYGEN COMPOUNDS
RATS
RODENTS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
VERTEBRATES
WATER