scholarly journals Roles of insulin and growth hormone in the adaptations of fatty acid synthesis in white adipose tissue during the lactation cycle in sheep

1988 ◽  
Vol 256 (3) ◽  
pp. 873-878 ◽  
Author(s):  
R G Vernon ◽  
E Finley
Keyword(s):  
Growth Hormone ◽  
Tissue Culture ◽  
Adipose Tissue ◽  
Fatty Acid ◽  
Fatty Acid Synthesis ◽  
Actinomycin D ◽  
Acid Synthesis ◽  
Serum Concentrations ◽  
Major Increase ◽  
Lactation Cycle

1. Lactation results in a substantial fall in the rate of fatty acid synthesis in sheep adipose tissue. 2. Maintenance of adipose tissue from non-lactating sheep in tissue culture for 24 or 48 h with insulin increased the rate of fatty acid synthesis. Dexamethasone, a glucocorticoid analogue, alone inhibited the rate of fatty acid synthesis, but enhanced the stimulatory effect of insulin. Growth hormone (somatotropin) antagonized the increase in the rate of fatty acid synthesis induced by insulin or insulin plus dexamethasone. 3. Maintenance of adipose tissue from lactating sheep in tissue culture resulted in a small increase in the rate of fatty acid synthesis after 24 h, and then a large increase in rate between 24 and 48 h of culture. The increase during the second 24 h period was dependent on the presence of insulin; this effect was enhanced by dexamethasone and inhibited by growth hormone. 4. The increase in the rate of fatty acid synthesis in tissue from non-lactating sheep and in tissue from lactating sheep during the major increase in rate was prevented by actinomycin D, an inhibitor of transcription. 5. Effects of insulin and growth hormone were observed with physiological concentrations of the hormones. 6. The study suggests that known changes in the serum concentrations of insulin and growth hormone are the primary causes of the changes in fatty acid synthesis in adipose tissue during the lactation cycle in sheep. 7. During lactation, adipose tissue becomes refractory to insulin in sheep; responsiveness is partly restored by tissue culture in the presence of insulin and dexamethasone.

scholarly journals Modulation of the activity of acetyl-CoA carboxylase and other lipogenic enzymes by growth hormone, insulin and dexamethasone in sheep adipose tissue and relationship to adaptations to lactation

1991 ◽  
Vol 274 (2) ◽  
pp. 543-548 ◽  
Author(s):  
R G Vernon ◽  
M C Barber ◽  
E Finley
Keyword(s):  
Growth Hormone ◽  
Tissue Culture ◽  
Adipose Tissue ◽  
Fatty Acid ◽  
Total Activity ◽  
Acid Synthesis ◽  
Active State ◽  
Acetyl Coa Carboxylase ◽  
Lipogenic Enzymes ◽  
Acetyl Coa

The mechanisms whereby growth hormone and dexamethasone modulate the stimulation of fatty acid synthesis by insulin in adipose tissue from lactating and non-lactating sheep have been investigated. Maintenance of adipose tissue from wethers (castrated male sheep) in tissue culture for 24 or 48 h with insulin resulted in an increased proportion of acetyl-CoA carboxylase being present in the active state; this effect was enhanced by dexamethasone and was antagonized by growth hormone. Lactation results in a decrease in both the total acetyl-CoA carboxylase of sheep adipose tissue and the proportion of the enzyme in the active state. Maintenance of adipose tissue from lactating sheep in tissue culture for 48 h in the presence of insulin plus dexamethasone increased markedly the proportion of acetyl-CoA carboxylase in the active state and increased slightly the total activity of the enzyme. Both of these effects were prevented by actinomycin D, and the change in activation status was prevented by growth hormone. Tissue culture for 6 days showed that growth hormone could also prevent the ability of insulin plus dexamethasone to increase the total activity of the enzyme. Analogous studies showed that insulin, dexamethasone and growth hormone modulated the activities of other lipogenic enzymes, but the effects were proportionately smaller than for acetyl-CoA carboxylase. Insulin also increased total protein synthesis in adipose tissue, but this was not antagonized by growth hormone. The results suggest that the fall in fatty acid synthesis in sheep adipose tissue during lactation is due to a decrease in both the total acetyl-CoA carboxylase activity and the proportion of the enzyme in the active state; these changes are probably induced by known changes in the serum concentrations of insulin and growth hormone. Lactation appears to result in the loss of a protein that is required for activation of acetyl-CoA carboxylase by insulin; production of this component appears to be prevented by growth hormone.

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 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

Low-protein, high-carbohydrate diet increases glucose uptake and fatty acid synthesis in brown adipose tissue of rats

Nutrition ◽  
2014 ◽  
Vol 30 (4) ◽  
pp. 473-480 ◽  
Author(s):  
Suélem Aparecida de França ◽  
Maísa Pavani dos Santos ◽  
Roger Vinícius Nunes Queiroz da Costa ◽  
Mendalli Froelich ◽  
Samyra Lopes Buzelle ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Fatty Acid ◽  
Brown Adipose Tissue ◽  
Fatty Acid Synthesis ◽  
Acid Synthesis ◽  
High Carbohydrate Diet ◽  
Carbohydrate Diet ◽  
High Carbohydrate ◽  
Low Protein ◽  
Brown Adipose

scholarly journals Regulation of fatty acid synthesis and malonyl-CoA content in mouse brown adipose tissue in response to cold-exposure, starvation or re-feeding

1987 ◽  
Vol 243 (2) ◽  
pp. 437-442 ◽  
Author(s):  
M G Buckley ◽  
E A Rath
Keyword(s):  
Adipose Tissue ◽  
Fatty Acid ◽  
Brown Adipose Tissue ◽  
Fatty Acid Synthesis ◽  
Cold Exposure ◽  
Acid Synthesis ◽  
Acetyl Coa Carboxylase ◽  
Acetyl Coa ◽  
Malonyl Coa ◽  
Brown Adipose

1. The effect of nutritional status on fatty acid synthesis in brown adipose tissue was compared with the effect of cold-exposure. Fatty acid synthesis was measured in vivo by 3H2O incorporation into tissue lipids. The activities of acetyl-CoA carboxylase and fatty acid synthetase and the tissue concentrations of malonyl-CoA and citrate were assayed. 2. In brown adipose tissue of control mice, the tissue content of malonyl-CoA was 13 nmol/g wet wt., higher than values reported in other tissues. From the total tissue water content, the minimum possible concentration was estimated to be 30 microM 3. There were parallel changes in fatty acid synthesis, malonyl-CoA content and acetyl-CoA carboxylase activity in response to starvation and re-feeding. 4. There was no correlation between measured rates of fatty acid synthesis and malonyl-CoA content and acetyl-CoA carboxylase activity in acute cold-exposure. The results suggest there is simultaneous fatty acid synthesis and oxidation in brown adipose tissue of cold-exposed mice. This is probably effected not by decreases in the malonyl-CoA content, but by increases in the concentration of free long-chain fatty acyl-CoA or enhanced peroxisomal oxidation, allowing shorter-chain fatty acids to enter the mitochondria independent of carnitine acyltransferase (overt form) activity.

Fatty acid synthesis in adipose tissues of physically trained rats in vivo

1983 ◽  
Vol 245 (1) ◽  
pp. E8-E13
Author(s):  
K. Tokuyama ◽  
H. Okuda
Keyword(s):  
Adipose Tissue ◽  
Fatty Acid ◽  
Fatty Acid Synthesis ◽  
Physical Training ◽  
Dark Period ◽  
Acid Synthesis ◽  
Free Access ◽  
Adipose Tissues ◽  
Brown Adipose

The effect of physical training on fatty acid synthesis in vivo was studied. After the rats had free access to a running wheel for 50 days, the rate of fatty acid synthesis estimated using 3H2O in adipose tissues of trained rats was about three times higher than that of sedentary rats in both the light and dark period. The rate of fatty acid synthesis in the liver but not in the brown adipose tissue was also slightly enhanced by physical training. The number of adipocytes was not affected, but the size of adipocytes was reduced by physical training. In trained rats, the rate of fatty acid synthesis in adipocytes whose diameter was similar to that of sedentary rats was about 10 times higher than that of sedentary rats. Within adipose tissue, the rate of fatty acid synthesis correlated positively to the diameter of adipocytes both in the sedentary and trained rats. These findings mean that the adaptive increase in fatty acid synthesis seen in adipocytes of trained rats is not secondary to the reduction in size of adipocytes.

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