Effect of Valine on the Control of Fatty Acid Synthesis in White Adipose Tissue of the Rat

1975 ◽  
Vol 53 (10) ◽  
pp. 1054-1060 ◽  
Author(s):  
Wayne M. Taylor ◽  
Mitchell L. Halperin
Keyword(s):  
Adipose Tissue ◽  
Fatty Acid ◽  
Fatty Acid Synthesis ◽  
Pyruvate Dehydrogenase ◽  
Incubation Medium ◽  
Acid Synthesis ◽  
Competitive Inhibitor ◽  
Final Concentration ◽  
Flow Through ◽  
Reduced Rate

In adipocytes from fed rats, the rate of fatty acid synthesis in the presence of glucose and insulin was inhibited 40% by valine (5 mm). This inhibition was largely abolished by the addition to the incubation medium of the transaminase inhibitor aminooxy acetate, and of pyruvate and agents which raise the intracellular pyruvate levels such as N,N,N1,N1-tetramethyl-p-phenylenediamine.Pyruvate output into the incubation medium from fat pads obtained from fed rats and incubated with glucose and insulin was decreased significantly by the addition of valine. When adipocytes were incubated under similar conditions, the final concentration of pyruvate in the incubation medium was 42 ± 1.6 μM under control conditions and approximately one third of this value in the presence of 2.5 mM valine.Valine had no significant effect on pyruvate dehydrogenase (lipoate) (EC 1.2.4.1) activity when assayed in homogenates prepared from adipose tissue previously incubated for 60 min with the amino acid. Although the ketoacid analogue of valine, α-ketoisovaleric acid, is a competitive inhibitor of pyruvate dehydrogenase (lipoate) (Ki = 1.4 mM), this cannot solely account for the valine-induced reduced rate of lipogenesis. Rather, the mechanism involves a reduction in pyruvate concentration and thereby a diminished flow through pyruvate dehydrogenase (lipoate). Details of the possible mechanism are discussed.

LIPOGENESIS IN ADIPOSE TISSUE OF MEAL-FED RATS: A POSSIBLE REGULATORY ROLE OF α-GLYCEROPHOSPHATE FORMATION

1967 ◽  
Vol 45 (2) ◽  
pp. 201-214 ◽  
Author(s):  
Gilbert A. Leveille
Keyword(s):  
Fatty Acids ◽  
Adipose Tissue ◽  
Fatty Acid ◽  
Fatty Acid Synthesis ◽  
Incubation Medium ◽  
Control Mechanism ◽  
Acid Synthesis ◽  
Fatty Acyl ◽  
Epididymal Adipose Tissue ◽  
Malic Dehydrogenase

The incorporation of acetate-1-14C into fatty acids by isolated epididymal adipose tissue of fed and fasted rats adapted to a single daily 2-hour meal (meal eaters) or fed ad libitum (nibblers) was investigated. Fasting (22 hours) markedly depressed lipogenesis whereas fatty acid synthesis increased linearly with time of refeeding in meal-fed but not in nibbling rats. The activities of glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, and NADP-malic dehydrogenase in adipose tissue of meal-fed or nibbling rats were not altered as a consequence of a 22-hour fast or of subsequent feeding for 2 hours. The incorporation of acetate-1-l4C into fatty acids by adipose tissue of fasted meal-eating or nibbling animals was markedly enhanced by the addition of unlabeled pyruvate or oxaloacetate to the incubation medium. This stimulatory effect was not observed with adipose tissue front fed meal-eating rats. The addition of unlabeled glucose and insulin to the incubation medium markedly enhanced acetate-1-14C incorporation into fatty acids by isolated adipose tissue and completely overcame any effect of fasting. Adipose tissue converted pyruvate-1-14C, -2-14C, or -3-14C to fatty acids and glyceride-glycerol. The results obtained are consistent with the functioning of a pathway in adipose tissue involving mitochondrial carboxylation of pyruvate to oxaloacetate, and equilibration of the newly formed oxaloacetate with malate and fumarate, followed by cytoplasmic conversion of oxaloacetate to phosphoenol pyruvate. The data are interpreted to support a control mechanism in which fatty acid synthesis is inhibited by tissue fatty acids and fatty acyl-CoA derivatives. The inhibition could in turn be reduced by the availability of α-glycerophosphate, for the esterification of fatty acids. This control mechanism is proposed as the explanation for the refeeding response observed in adipose tissue of meal-fed rats.

scholarly journals Lipogenic enzymes in rat maternal adipose tissue in the perinatal period

1980 ◽  
Vol 186 (3) ◽  
pp. 937-944 ◽  
Author(s):  
P A Sinnett-Smith ◽  
R G Vernon ◽  
R J Mayer
Keyword(s):  
Adipose Tissue ◽  
Fatty Acid ◽  
Fatty Acid Synthesis ◽  
Pyruvate Dehydrogenase ◽  
Fatty Acid Biosynthesis ◽  
Specific Activity ◽  
Fatty Acid Synthetase ◽  
Acid Synthesis ◽  
Acetyl Coa Carboxylase ◽  
Acid Biosynthesis

1. The specific activities of fatty acid synthetase, acetyl-CoA carboxylase and pyruvate dehydrogenase were measured in rat adipose-tissue extracts in pregnancy and lactation. Fatty acid synthetase specific activity correlates very closely with the rate of fatty acid synthesis, the enzyme specific activity decreasing after mid-pregnancy in a manner very similar to the rate of fatty acid synthesis. Acetyl-CoA carboxylase specific activity also decreases dramatically after mid-pregnancy. Initial pyruvate dehydrogenase specific activity shows a decrease between 2 days pre partum and 2 days post partum, but total enzyme activity shows no significant change in the same period. 2. Immunotitrations of fatty acid synthetase and pyruvate dehydrogenase activities were carried out; the titrations showed that the change in the fatty acid synthetase activity is due to a change in the enzyme amount; the amount of pyruvate dyhydrogenase does not change. Therefore the decrease in fatty acid biosynthesis in subcutaneous and parametrial adipose tissue in late pregnancy and early lactation is associated with a decrease in the amount of at least one of the enzymes involved in fatty acid biosynthesis. The correlation of these events with known hormonal changes is discussed.

scholarly journals Evidence that fatty acid synthesis in the interscapular brown adipose tissue of cold-adapted rats is increased in vivo by insulin by mechanisms involving parallel activation of pyruvate dehydrogenase and acetyl-coenzyme A carboxylase

1977 ◽  
Vol 166 (3) ◽  
pp. 627-630 ◽  
Author(s):  
J G McCormack ◽  
R M Denton
Keyword(s):  
Adipose Tissue ◽  
Fatty Acid ◽  
Brown Adipose Tissue ◽  
Fatty Acid Synthesis ◽  
Pyruvate Dehydrogenase ◽  
Plasma Insulin ◽  
Acid Synthesis ◽  
Interscapular Brown Adipose Tissue ◽  
Cold Adapted ◽  
Brown Adipose

Plasma insulin concentrations in cold-adapted rats were altered acutely by administration of glucose or anti-insulin serum. Rates of fatty acid synthesis in interscapular brown adipose tissue were determined from the incorporation of 3H from 3H2O into tissue lipid. Rates of synthesis were greatly elevated after glucose administration and markedly decreased after injection with anti-insulin serum. Parallel changes in the initial activities of both acetyl-CoA carboxylase and pyruvate dehydrogenase were observed under these conditions, but no changes in total activities were evident. The results suggest that this tissue is an important site of fatty acid synthesis in the cold-adapted rat and that this feature of the tissue is sensitive to changes in plasma insulin concentrations.

scholarly journals Regulation of glycolysis and fatty acid synthesis from glucose in sheep adipose tissue

1982 ◽  
Vol 206 (3) ◽  
pp. 577-586 ◽  
Author(s):  
James P. Robertson ◽  
Anne Faulkner ◽  
Richard G. Vernon
Keyword(s):  
Tissue Culture ◽  
Adipose Tissue ◽  
Fatty Acid ◽  
Pyruvate Kinase ◽  
Fatty Acid Synthesis ◽  
Pyruvate Dehydrogenase ◽  
Glucose Oxidation ◽  
Acid Synthesis ◽  
Pentose Phosphate ◽  
Glucose Carbon

1. The following were measured in adipose-tissue pieces, obtained from 7–9 month-old sheep, before or after the tissue pieces had been maintained in tissue culture for 24 h: the rates of synthesis from glucose of fatty acids, acylglycerol glycerol, pyruvate and lactate; the rate of glucose oxidation to CO2; the rate of glucose oxidation via the pentose phosphate pathway; the activities of hexokinase, glucose 6-phosphate dehydrogenase, phosphofructokinase, pyruvate kinase, pyruvate dehydrogenase and ATP citrate lyase; the intra- and extra-cellular water content; the concentration of various metabolites and ATP, ADP and AMP. 2. The proportion of glucose carbon converted into the various products in sheep adipose tissue differs markedly from that observed in rat adipose tissue. 3. There was a general increase in the rate of glucose utilization by the adipose-tissue pieces after maintenance in tissue culture; largest changes were seen in the rates of glycolysis and fatty acid synthesis from glucose. These increases are paralleled by an increase in pyruvate kinase activity. There was no change in the activities of the other enzymes as measured, although the net flux through all the enzymes increased. 4. Incubation of fresh adipose-tissue pieces for 2–6h led to an increase in the affinity of pyruvate kinase for phosphoenolpyruvate. 5. The rate of pyruvate production by glycolysis was greater than the activity of pyruvate dehydrogenase of the tissue. 6. The results suggest that both pyruvate kinase and pyruvate dehydrogenase have important roles in restricting the utilization of glucose carbon for fatty acid synthesis in sheep adipose tissue.

scholarly journals Acute effects in vivo of anti-insulin serum on rates of fatty acid synthesis and activities of acetyl-coenzyme A carboxylase and pyruvate dehydrogenase in liver and epididymal adipose tissue of fed rats

1976 ◽  
Vol 160 (2) ◽  
pp. 413-416 ◽  
Author(s):  
D Stansbie ◽  
R W Brownsey ◽  
M Crettaz ◽  
R M Denton
Keyword(s):  
Adipose Tissue ◽  
Fatty Acid ◽  
Fatty Acid Synthesis ◽  
Pyruvate Dehydrogenase ◽  
Acid Synthesis ◽  
Epididymal Adipose Tissue ◽  
Acetyl Coa Carboxylase ◽  
Acetyl Coa ◽  
Carboxylase Activity

Plasma insulin concentrations in fed rats were altered acutely by administration of glucose or anti-insulin serum. Rates of fatty acid synthesis in adipose tissue and liver were estimated from the incorporation of 3H from 3H2O. In the adipose tissue dehydrogenase and acetyl-CoA carboxylase were evident. In liver, although changes in rates of fatty acid synthesis were found, the initial activity of pyruvate dehydrogenase did not alter, but small parallel changes in acetyl-CoA carboxylase activity were observed.

scholarly journals Effects of Prolactin in Vitro on Fatty Acid Synthesis in Rat Adipose Tissue

1959 ◽  
Vol 234 (12) ◽  
pp. 3111-3114 ◽  
Author(s):  
Albert I. Winegrad ◽  
Walter N. Shaw ◽  
Francis D.W. Lukens ◽  
William C. Stadie
Keyword(s):  
Adipose Tissue ◽  
Fatty Acid ◽  
Fatty Acid Synthesis ◽  
Acid Synthesis ◽  
Rat Adipose Tissue
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