scholarly journals The effect of dietary carbohydrate and fat on the activities of some enzymes responsible for glycerolipid synthesis in rat liver

1978 ◽  
Vol 174 (2) ◽  
pp. 535-541 ◽  
Author(s):  
H P Glenny ◽  
M Bowley ◽  
S L Burditt ◽  
J Cooling ◽  
P H Pritchard ◽  
...  
Keyword(s):  
Corn Oil ◽  
Specific Activity ◽  
Male Rats ◽  
Dihydroxyacetone Phosphate ◽  
Triacylglycerol Synthesis ◽  
Choline Phosphotransferase ◽  
Phosphatidate Phosphohydrolase ◽  
Glycerolipid Synthesis ◽  
Starch Diet

1. Male rats were fed for 14 days on diets containing (by wt.) 53% of starch, or on diets in which 20% of the starch was replaced by sucrose, corn oil or lard. 2. The hepatic activities of the microsomal glycerol phosphate acyltransferase, dihydroxyacetone phosphate acyltransferase, phosphatidate cytidylyltransferase, diacylglycerol acyltransferase and choline phosphotransferase, and of the soluble phosphatidate phosphohydrolase, were measured. 3. The soluble phosphatidate phosphohydrolase activity was higher in those rats fed on lard than in those fed on the starch diet. Choline phosphotransferase activity was higher in the rats fed on corn oil than in those fed on the starch diet. 4. The rate of hepatic glycerolipid synthesis was measured in vivo 1 min after injection of [1,3-3H]glycerol and [1-14C]palmitate into the portal veins. 5. The relative rate of phosphatidylcholine synthesis in vivo was increased after feeding with corn oil and the higher specific activity of choline phosphotransferase may contribute to this result. The equivalent rate of triacylglycerol synthesis was increased by feeding with lard rather than corn oil, and the increased activity of phosphatidate phosphohydrolase may partly explain this. The latter changes probably contribute to the increased concentration of triacylglycerol which other authors have observed in the livers and sera of animals fed on saturated and monounsaturated fats.

scholarly journals Effects of chronic modification of dietary fat and carbohydrate on the insulin, corticosterone and metabolic responses of rats fed acutely with glucose, fructose or ethanol

1981 ◽  
Vol 200 (2) ◽  
pp. 275-283 ◽  
Author(s):  
David N. Brindley ◽  
June Cooling ◽  
Helen P. Glenny ◽  
Susan L. Burditt ◽  
I. Sarah McKechnie
Keyword(s):  
Dietary Fat ◽  
Corn Oil ◽  
Male Rats ◽  
Triacylglycerol Synthesis ◽  
Phosphatidate Phosphohydrolase ◽  
Corticosterone Response ◽  
Pelleted Diet ◽  
Increased Activity ◽  
Lard Diet ◽  
Starch Diet

1. Male rats were fed for 14 days on powdered diets containing (by weight) 53% of starch, or on diets in which 20g of starch per 100g of diet was replaced by lard or corn oil. They were then fed acutely by stomach tube with a single dose of glucose, fructose or ethanol of equivalent energy contents, or with 0.15m-NaCl. The serum concentrations of corticosterone, insulin, glucose, glycerol, triacylglycerol and cholesterol were measured up to 6h after this treatment. 2. Feeding saline (0.9% NaCl) acutely to the rats maintained on the three powdered diets produced a small transient increase in circulating corticosterone that was similar to that in rats maintained on the normal 41B pelleted diet. 3. Feeding glucose acutely to the rats on the powdered diets produced peak concentrations of corticosterone that were 2–3-fold higher than those seen in rats maintained on the 41B diet. The duration of this response increased in the order starch diet<lard diet<corn-oil diet. This abnormal corticosterone response to glucose feeding appeared to be responsible for an increased activity in phosphatidate phosphohydrolase in the livers of rats fed the starch and lard diets of 2.9- and 4.9-fold respectively. The latter increase was similar to that produced by ethanol, whereas glucose did not increase the phosphohydrolase activity in the liver of rats maintained on the 41B diet. 4. Feeding fructose acutely produced even more marked increases than glucose in the concentrations of circulating corticosterone in rats given the powdered diets, but unlike glucose did not increase circulating insulin. The duration of the corticosterone response again increased in the order starch diet<lard diet<corn-oil diet. The concentrations of circulating glucose were increased by fructose feeding in rats maintained on these diets, but they were not altered in the rats maintained on the 41B pellets. A prolonged increase in serum corticosterone concentrations was also observed when fructose was fed to rats maintained on pelleted diets enriched with corn oil or beef tallow rather than with starch or sucrose. However, these effects were less marked than those seen with rats fed on the powdered diets. 5. These results are discussed in relation to the mechanism whereby high dietary fat exaggerates the effects of ethanol, fructose and sorbitol in stimulating triacylglycerol synthesis in the liver.

scholarly journals The activities of lipoprotein lipase and of enzymes involved in triacylglycerol synthesis in rat adipose tissue. Effects of starvation, dietary modification and of corticotropin injection

1981 ◽  
Vol 200 (2) ◽  
pp. 285-294 ◽  
Author(s):  
N Lawson ◽  
A D Pollard ◽  
R J Jennings ◽  
M I Gurr ◽  
D N Brindley
Keyword(s):  
Adipose Tissue ◽  
Lipoprotein Lipase ◽  
Corn Oil ◽  
Diacylglycerol Acyltransferase ◽  
Dietary Modification ◽  
Dihydroxyacetone Phosphate ◽  
Glycerol Phosphate ◽  
Triacylglycerol Synthesis ◽  
Phosphatidate Phosphohydrolase ◽  
Starch Diet

1. The effects of dietary modification, including starvation, and of corticotropin injection on the activities of acyl-CoA synthetase, glycerol phosphate acyltransferase, dihydroxyacetone phosphate acyltransferase, phosphatidate phosphohydrolase, diacylglycerol acyltransferase and lipoprotein lipase were measured in adipose tissue. 2. Lipoprotein lipase activities in heart were increased and those in adipose tissue were decreased when rats were fed on diets enriched with corn oil or beef tallow rather than with sucrose or starch. The lipoprotein lipase activity was lower in the adipose tissue of rats fed on the sucrose rather than on the starch diet. 3. Rats fed on the beef tallow diet had slightly higher activities of the total glycerol phosphate acyltransferase in adipose tissue than did rats fed on the sucrose or starch diet. The diacylglycerol acyltransferase and the mitochondrial glycerol phosphate acyltransferase activities were higher for the rats fed on the tallow diet than for those fed on the corn-oil diet. 4. Starvation significantly decreased the activities of lipoprotein lipase (after 24 and 48 h), acyl-CoA synthetase (after 24 h) and of the mitochondrial glycerol phosphate acyltransferase and the N-ethylmaleimide-insensitive dihydroxyacetone phosphate acyltransferase (after 48 h) in adipose tissue. The activities of the microsomal glycerol phosphate acyltransferase, diacylglycerol acyltransferase and the soluble phosphatidate phosphohydrolase were not significantly changed after 24 or 48 h of starvation. 5. The activities of lipoprotein lipase and phosphatidate phosphohydrolase in adipose tissue were decreased 15 min after corticotropin was injected into rats during November to December. No statistically significant differences were found when these experiments were performed during March to September. These differences may be related to the seasonal variation in acute lipolytic responses. 6. These results are discussed in relation to the control of triacylglycerol synthesis and lipoprotein metabolism.

scholarly journals The effects of diet on the esterification of glycerol phosphate, dihydroxyacetone phosphate and 2-hexadecylglycerol by homogenates of rat adipose tissue

1976 ◽  
Vol 160 (3) ◽  
pp. 701-706 ◽  
Author(s):  
P F Dodds ◽  
D N Brindley ◽  
M I Gurr
Keyword(s):  
Adipose Tissue ◽  
Beef Tallow ◽  
Corn Oil ◽  
Specific Activity ◽  
Body Weight Gain ◽  
Male Rats ◽  
Dihydroxyacetone Phosphate ◽  
Glycerol Phosphate ◽  
Triacylglycerol Content ◽  
Rat Adipose Tissue

1. Male rats were fed for 5 weeks after weaning on a diet containing (by weight) 59% of starch or on diets that contained 39% of starch and 20% of either sucrose, beef tallow or corn oil. 2. The rats fed on the beef tallow consumed more energy than did the rats fed on the starch and sucrose diets. The rats fed on the corn oil drank less water than did the other groups of rats. 3. There were no significant differences between the four groups in terms of body-weight gain, epididymal-fat-pad weight and in the size, number and triacylglycerol content of the adipocytes in the fat-pads. 4. There was a significant correlation (P < 0.001) between the activities of glycerol phosphate acyltransferase and monoacylglycerol acyltransferase in individual rats. Both of these activities were highest in the group fed on the high-starch diet and both correlated with the consumption of glucose by individual rats in the four groups. 5. The percentage of glycerol phosphate converted into diacylglycerol and triacylglycerol was positively correlated with the mean diameters, surface area and triacylglycerol content of the adipocytes for individual rats and was greates in the sucrose-fed rats. 6. The specific activity of dihydroxyacetone phosphate acyltransferase was highest in the rats fed on beef tallow. This activity was positively correlated with the energy intake for all dietary groups over the 5-week feeding period. 7. The results are discussed in terms of the functions of the three routes of glycerolipid synthesis in adipose tissue.

scholarly journals In vivo uptake of [14C]leucine by skeletal muscle ribosomes after injury in rats fed two levels of protein

1969 ◽  
Vol 23 (2) ◽  
pp. 271-280 ◽  
Author(s):  
V. R. Young ◽  
P. C. Huang
Keyword(s):  
Skeletal Muscle ◽  
Specific Activity ◽  
Male Rats ◽  
Thigh Muscle ◽  
Left Femur ◽  
The Right ◽  
And Control ◽  
The Relationship ◽  
In Vivo Uptake

1. After 14 days on a diet containing 5 or 25% casein male rats received a fracture of the left femur. Four hours before they were killed the injured and control rats were injected with [1-14C]leucine; the incorporation of radioactivity into an isolated fraction of skeletal muscle ribosomes was studied 6, 12, 24, 48, 72, 96 and 228 h after injury.2. The incorporation of [14C]leucine into the ribosome fraction in right thigh muscles dropped to 40% of control values 72 h after fracture in well-nourished rats and after 96 h with diets containing 5 or 25%, casein.3. The specific activity of the trichloroacetic acid-soluble fraction of muscle from injured rats was equal to or higher than that of the controls during the first 72 h but lower at 96 h.4. These results suggest that a reduced incorporation of amino acids by ribosomes from the right thigh muscle occurred on day 3 after fracture in the group receiving 25% casein but not in the group receiving 5% casein.5. Muscle RNA and DNA concentrations were not affected by the injury.6. The relationship between these findings and the loss of muscle N after injury is discussed.

scholarly journals The effects of cortisol, corticotropin and thyroxine on the synthesis of glycerolipids and on the phosphatidate phosphohydrolase activity in rat liver

1978 ◽  
Vol 176 (3) ◽  
pp. 777-784 ◽  
Author(s):  
Helen P. Glenny ◽  
David N. Brindley
Keyword(s):  
Body Weight ◽  
Body Weight Gain ◽  
Relative Rate ◽  
Male Rats ◽  
Very Low Density Lipoproteins ◽  
Triacylglycerol Synthesis ◽  
Phosphatidate Phosphohydrolase ◽  
Ethanol Feeding ◽  
Enzyme Adaptation ◽  
Subtotal Hepatectomy

1. Male rats were injected daily for 5 days with 0.15m-NaCl, corticotropin, cortisol or l-thyroxine and the rates of glycerolipid synthesis were measured in the livers after intraportal injection of [14C]palmitate and [3H]glycerol. 2. Injection of all three hormones decreased the rates of body-weight gain. 3. Cortisol treatment increased the weight of the liver relative to body weight. 4. Thyroxine treatment increased the relative rate of triacylglycerol synthesis from [3H]glycerol and decreased the relative accumulation of 3H and 14C in diacylglycerol. It did not significantly alter the accumulation of these isotopes in phosphatidate nor the activity of the soluble phosphatidate phosphohydrolase in the total liver. However, this activity increased by 1.5-fold when expressed relative to the soluble protein of the liver. The increased triacylglycerol synthesis appears to be related to a general increase in the turnover of fatty acids in the liver. 5. Treatment with cortisol and corticotropin increased the relative rate of triacylglycerol synthesis from [3H]glycerol, decreased the accumulation of 3H in phosphatidate and increased the flux of both isotopes from phosphatidate to diacylglycerol. This appeared to be caused by the increased activity of the soluble phosphatidate phosphohydrolase that was observed in the livers of the cortisol-treated rats. 6. It is proposed that cortisol could be directly or indirectly involved in increasing the activity of hepatic phosphatidate phosphohydrolase in starvation, diabetes, laparotomy, subtotal hepatectomy, liver damage, ethanol feeding and in obesity. This enzyme adaptation could contribute to the potential of the liver to increase its synthesis and accumulation of triacylglycerols or to secrete very-low-density lipoproteins.

scholarly journals Characterization of glutathione S-transferases in rat kidney. Alteration of composition by cis-platinum

1988 ◽  
Vol 252 (1) ◽  
pp. 127-136 ◽  
Author(s):  
G M Trakshel ◽  
M D Maines
Keyword(s):  
Specific Activity ◽  
Rat Kidney ◽  
Male Rats ◽  
Glutathione S Transferase ◽  
Aberrant Form ◽  
Glutathione S Transferases ◽  
Exchange Matrix ◽  
Rat Kidney Cytosol

We have developed chromatographic and mathematical protocols that allowed the high resolution of glutathione S-transferase (GST) subunits, and the identification of a previously unresolved GST monomer in rat kidney cytosol; the monomer was identified tentatively as subunit 6. Also, an aberrant form of GST 7-7 dimer appeared to be present in the kidney. This development was utilized to illustrate the response of rat kidney GST following cis-platinum treatment in vivo. Rat kidney cytosol was separated into three ‘affinity families’ of GST activity after elution from a GSH-agarose matrix. The affinity peaks were characterized by quantitative differences in their subunit and dimeric compositions as determined by subsequent chromatography on a cation-exchange matrix and specific activity towards substrates. By use of these criteria, the major GST dimers of affinity peaks were tentatively identified. The major GST dimers in peak I were GST 1-1 and 1-2, in affinity peak II it was GST 2-2, and in peak III they were GST 3-3 and 7-7. GST 3-6 and/or 4-6, which have not been previously resolved in kidney cytosol, were also present in peak II. Alterations in the kidney cytosolic GST composition of male rats were detected subsequent to the administration of cis-platinum (7.0 mg/kg subcutaneously, 6 days). This treatment caused a pronounced alteration in the GST profile, and the pattern of alteration was markedly different from that reported for other chemicals in the kidney or in the liver. In general, the cellular contents of the GSTs of the Alpha and the Mu classes decreased and increased respectively. It is postulated that the decrease in the Alpha class of GSTs by cis-platinum treatment may be related to renal cortical damage and the loss of GSTs in the urine. The increase in the Mu class of GSTs could potentially stem from a lowered serum concentration of testosterone; the latter is a known effect of cis-platinum treatment.

scholarly journals The phospholipid-dependence of uridine diphosphate glucuronyltransferase. Effect of protein deficiency on the phospholipid composition and enzyme activity of rat liver microsomal fraction

1974 ◽  
Vol 137 (3) ◽  
pp. 567-574 ◽  
Author(s):  
A. B. Graham ◽  
B. G. Woodcock ◽  
G. C. Wood
Keyword(s):  
Specific Activity ◽  
Phospholipid Composition ◽  
Fold Increase ◽  
Protein Deficiency ◽  
Male Rats ◽  
Striking Difference ◽  
Uridine Diphosphate ◽  
Microsomal Membranes ◽  
Microsomal Phospholipid

After force-feeding a protein-free diet to male rats for 5–7 days a substantial (2.4-fold) increase in the specific activity of the liver microsomal enzyme UDP-glucuronyltransferase (EC 2.4.1.17) was observed. A similar activation of the enzyme occurred when rats were fed on a low-protein (5%, w/w, casein) diet for 60 days. Although both the short- and long-term protein-deficient diets decreased the contents of microsomal protein and phospholipid in liver tissue they did not significantly alter the ratio of these major membrane components. Protein deficiency profoundly altered the phospholipid composition of microsomal membranes. The most striking difference in microsomal phospholipid composition between control and protein-deficient rats was their content of lysophosphatides. Whereas microsomal membranes from protein-deficient rats contained significant proportions of lysophosphatidylcholine and lysophosphatidylethanolamine very little or no lysophosphatides were detected in control preparations. Pretreatment of microsomal fractions from normal rats with phospholipase A markedly increased their UDP-glucuronyltransferase activity as did their pretreatment with lysophosphatidylcholine. It is concluded that the quantities of lysophosphatides present in microsomal membranes from protein-deficient rats were sufficient to have caused the increased UDP-glucuronyltransferase activities of these preparations. Evidence is presented suggesting that these changes in microsomal phospholipid composition and UDP-glucuronyltransferase activity caused by protein deficiency reflect changes that occur in vivo. The possible physiological significance of these findings is discussed.

scholarly journals The effect of chronic diabetes, induced by streptozotocin, on the activities of some enzymes of glycerolipid synthesis in rat liver

1977 ◽  
Vol 168 (2) ◽  
pp. 147-153 ◽  
Author(s):  
P H Whiting ◽  
M Bowley ◽  
R G Sturton ◽  
P H Pritchard ◽  
D N Brindley ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Single Dose ◽  
Rat Liver ◽  
Diacylglycerol Acyltransferase ◽  
Diabetic Rats ◽  
Glycerol Phosphate ◽  
Choline Phosphotransferase ◽  
Phosphatidate Phosphohydrolase ◽  
Glycerolipid Synthesis ◽  
Increased Activity

1. Rats were injected with a single dose of 35mg of streptozotocin/kg body wt. They exhibited a diabetes that was characterized by glycosuria, polyuria, polydipsia, hyperphagia, hyperglycaemia, increased concentrations of unesterified fatty acids, glycerol and triacylglycerols in the serum and an increased activity of glucose 6-phosphatase in the liver. 2. After 10 weeks the hepatic activities of the microsomal glycerol phosphate acyltransferase, phosphatidate phosphohydrolase, phosphatidate cytidylyltransferase, diacylglycerol acyltransferase, choline phosphotransferase, CDP-diacylglycerolx—inositol phosphatidyltransferase and the soluble phosphatidate phosphohydrolase were measured. 3. The only significant changes were an increase in the activity of the soluble phosphatidate phosphohydrolase and a decrease in that of the CDP-diacylglycerol—inositol phosphatidyltransferase in the diabetic rats. 4. These results are discussed in relation to the control of glycerolipid synthesis.

scholarly journals Effects of streptozotocin-diabetes and insulin administration in vivo or in vitro on the activities of five enzymes in the adipose-tissue triacylglycerol-synthesis pathway

1987 ◽  
Vol 243 (1) ◽  
pp. 289-292 ◽  
Author(s):  
E D Saggerson ◽  
C A Carpenter
Keyword(s):  
Insulin Treatment ◽  
Streptozotocin Diabetes ◽  
Diacylglycerol Acyltransferase ◽  
Fatty Acyl ◽  
Diabetic Rats ◽  
Insulin Administration ◽  
Triacylglycerol Synthesis ◽  
Phosphatidate Phosphohydrolase

At 2 days after administration of streptozotocin (100 mg/kg), activities in rat epididymal fat-pads of the following enzymes were significantly decreased: fatty acyl-CoA synthetase (FAS), mitochondrial and microsomal forms of glycerolphosphate acyltransferase (GPAT), monoacylglycerolphosphate acyltransferase (MGPAT) and Mg2+-dependent phosphatidate phosphohydrolase (PPH). There were no significant changes in diacylglycerol acyltransferase or Mg2+-independent PPH. Insulin administration to diabetic rats over 2 days restored activities of FAS, both forms of GPAT, MGPAT and Mg2+-dependent PPH. Significant restoration of all five activities was also seen 2 h after a single administration of insulin, but was not observed 45 min after insulin treatment. Insulin significantly increased all five enzyme activities when adipocytes from diabetic rats were incubated for 2 h with a mixture of glucose, lactate, pyruvate and amino acids.

scholarly journals Effects of chronic modification of dietary fat and carbohydrate in rats. The activities of some enzymes of hepatic glycerolipid synthesis and the effects of corticotropin injection

1981 ◽  
Vol 200 (2) ◽  
pp. 265-273 ◽  
Author(s):  
N Lawson ◽  
R J Jennings ◽  
A D Pollard ◽  
R G Sturton ◽  
S J Ralph ◽  
...  
Keyword(s):  
Beef Tallow ◽  
Corn Oil ◽  
Urate Oxidase ◽  
Dihydroxyacetone Phosphate ◽  
High Fat ◽  
Glycerol Phosphate ◽  
Acyltransferase Activity ◽  
High Fat Diets ◽  
Fat Diets ◽  
Starch Diet

1. Rats were fed on diets enriched with starch, sucrose, corn oil or beef tallow for 3 weeks and the activities of various enzymes in the liver were measured. 2. The mitochondrial glycerol phosphate acyltransferase activity was lower in rats fed on the starch diet than on the two high-fat diets. 3. The non-microsomal (presumably peroxisomal) dihydroxyacetone phosphate acyltransferase activity was higher in rats fed on the starch diet and corn-oil diets than in those fed on the sucrose and beef-tallow diets. Urate oxidase activity was higher in rats fed on the starch diet than in the three other groups. There were no significant differences in the activity of acyl-CoA oxidase among the groups. 4. The activity of soluble phosphatidate phosphohydrolase was not significantly different among the dietary groups. There were increases of 3.3--4.3-fold in this activity in the dietary groups 6h after injection of corticotropin. The equivalent increases for the mitochondrial glycerol phosphate acyltransferase were 1.4--1.6 fold. 5. The corticosterone responses to the corticotropin injection were not significantly different between dietary groups. However, the corticosterone response of the rats fed on the two high-fat diets was prolonged when the rats were given an acute load of fructose [Brindley, Cooling, Glenny, Burditt & McKechnie (1981) Biochem. J. 200. 275--283]. 6. Rats fed on the high-fat diets had higher concentrations of circulating cholesterol than those fed on the starch and sucrose diets. Serum triacylglycerol concentrations were lower in the rats fed on the starch diet than in the three other groups. 7. The results are discussed in terms of the relationship between diet, hormonal balance and hepatic glycerolipid metabolism.

Sign in / Sign up

Export Citation Format

Share Document