scholarly journals Activity of selected gluconeogenic and lipogenic enzymes in bovine rumen mucosa, liver and adipose tissue

1969 ◽  
Vol 114 (1) ◽  
pp. 83-88 ◽  
Author(s):  
Jerry W. Young ◽  
Sylvia L. Thorp ◽  
Helen Z. De Lumen
Keyword(s):  
Enzyme Activity ◽  
Adipose Tissue ◽  
Dehydrogenase Activity ◽  
Malic Enzyme ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Lipogenic Enzymes ◽  
Adipose Tissues ◽  
Cleavage Enzyme ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Enzyme Patterns

The activities of phosphoenolpyruvate carboxykinase, ‘malic enzyme’, citrate-cleavage enzyme and glucose 6-phosphate dehydrogenase were assayed in homogenates of rumen mucosa, liver and adipose tissue of cattle. Rumen mucosa cytoplasm contained activities of ‘malic enzyme’ approximately sevenfold those of phosphoenolpyruvate carboxykinase, suggesting that the conversion of propionate into lactate by rumen mucosa involves ‘malic enzyme’. Neither starvation for 8 days nor feeding with a concentrate diet for at least 3 months before slaughter produced enzyme patterns in the tissues different from those in cattle given only hay, except that the all-concentrate diet caused increased activities of glucose 6-phosphate dehydrogenase and ‘malic enzyme’ in adipose tissues. Rumen mucosa, liver and adipose tissue contained phosphoenolpyruvate carboxykinase activity. ‘Malic enzyme’ was absent in liver. Citrate-cleavage enzyme activity was present in liver and adipose tissue but was quite low in rumen mucosa. Liver contained much less glucose 6-phosphate dehydrogenase activity than rumen mucosa or adipose tissue.

Lipogenic Enzymes of Rat Liver and Adipose Tissue. Dietary Variations and Effect of Polychlorinated Biphenyls

1994 ◽  
Vol 49 (9-10) ◽  
pp. 665-678 ◽  
Author(s):  
Meinrad Boll ◽  
Lutz W. D. Weber ◽  
Andreas Stampfl ◽  
Burkhard Messner
Keyword(s):  
Adipose Tissue ◽  
Polychlorinated Biphenyls ◽  
Enzyme Activities ◽  
Time Course ◽  
Fatty Acid Synthase ◽  
Lipogenic Enzymes ◽  
Brown Adipose ◽  
Cleavage Enzyme ◽  
Order Of Magnitude ◽  
Glucose 6 Phosphate Dehydrogenase

Abstract The lipogenic enzymes fatty acid synthase (FAS; EC 2.3.1.85), citrate cleavage enzyme (CCE; EC 4.1.3.8), malic enzyme (ME; EC 1.1.1.40), glucose-6-phosphate dehydrogenase (G6PDH; EC 1.1.1.49) and 6-phosphogluconate dehydrogenase (PGDH; EC 1.1.1.44) were investigated in liver and in brown adipose tissue (BAT) of Wistar rats under various dietary conditions and in the presence of 15 to 250 ppm (approximately 0.045-0.75 μmol/kg chow) polychlorinated biphenyls (PCBs).In response to refeeding starved animals, enzyme activities in both tissues increased to above normal levels and thereafter exhibited pronounced oscillations of their activities. The extent of increase depended on the carbohydrate and fat content of the diet. The lipogenic enzymes could be grouped in two categories according to their sensitivity to dietary carbohydrate: FAS and CCE responded faster to smaller changes in dietary composition, while ME, G6PDH and PGDH required larger changes and more time to respond.Diet-induced alterations of enzyme activities were of the same order of magnitude in liver and BAT. They were age-dependent, being more pronounced in young animals. Independent of the type of dietary manipulations, activities changed in a coordinate fashion, i.e., the changes of the activities of all 5 enzymes occurred at similar ratios to each other with an identical time course.Feeding PCB-containing diets resulted in a considerable increase of the activities of the lipogenic enzymes in liver, which was significantly greater with ME, G 6PD H and PGDH. The effect was dose-dependent but transient. In liver the response to PCB feeding was iden­tical in male and female animals, whereas in BAT lipogenic activities increased in females, but decreased in males.Refeeding starved animals with a PCB-containing diet led to an additional stimulation of the normal refeeding-induced increase of the enzyme activities in liver and BAT. This PCB-induced increase was 2-fold for FAS and CCE, but up to 15-fold for the other enzymes. All PCB-induced effects were significantly less pronounced in old than in young animals.In primary hepatocytes activities increased in hormone-free medium in the presence of PCBs. While activity was induced in insuline-and triiodothyronine-containing medium, this increase was significantly greater with PCBs present.

Hormonal regulation of malic enzyme and glucose-6-phosphate dehydrogenase in brown adipose tissue

1993 ◽  
Vol 264 (6) ◽  
pp. E874-E881 ◽  
Author(s):  
S. D. Carvalho ◽  
N. Negrao ◽  
A. C. Bianco
Keyword(s):  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
Malic Enzyme ◽  
Hormonal Regulation ◽  
Inhibitory Effect ◽  
Thyroid Status ◽  
Brown Adipose ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Dose Dependent ◽  
Intact Rats

The activities of malic enzyme (ME) and glucose-6-phosphate dehydrogenase (G-6-PDH), two NADPH-generating lipogenic enzymes, were measured in brown adipose tissue (BAT) of rats undergoing various neurohormonal manipulations. Methimazole-induced hypothyroidism doubled the activity of these two enzymes but, surprisingly, triiodothyronine (T3) given to hypothyroid rats caused a time- and dose-dependent stimulation of up to three- to fourfold. Unilateral BAT denervation modestly reduced the activity of these enzymes (approximately 30%) and failed to prevent the stimulation induced by hypothyroidism, whereas growth hormone (GH) successfully blocked this effect of hypothyroidism. Insulin stimulated both enzymes regardless of the thyroid status but failed to abolish the inhibitory effect of GH. In intact rats, cold exposure caused a time-dependent increase in the activity of both ME and G-6-PDH, which reached 5.2- and 3-fold, respectively, after 96 h. This cold-induced stimulation was not observed in hypothyroid rats, but it was restored by physiological doses of thyroxine (800 ng.100 g body wt-1.24 h-1). Replacement with T3 (300 ng.100 g body wt-1.24 h-1), in contrast, did not have this effect. In hypothyroid rats with hemidenervation of BAT, norepinephrine (NE) modestly increased ME and G-6-PDH activities in the denervated side, with little or no effect in the intact side. Receptor-saturating doses of T3 (50 micrograms.100 g body wt-1.day-1 over 48 h) stimulated two- and threefold both enzymes in both sides, reducing or obliterating the effect of denervation. The data suggest a complex neurohormonal regulation of the activity of ME and G-6-PDH in BAT.(ABSTRACT TRUNCATED AT 250 WORDS)

Metabolic alterations after dehydroepiandrosterone treatment in Zucker rats

1984 ◽  
Vol 246 (2) ◽  
pp. E123-E128 ◽  
Author(s):  
A. Shepherd ◽  
M. P. Cleary
Keyword(s):  
Enzyme Activity ◽  
Adipose Tissue ◽  
Fatty Acid ◽  
Malic Enzyme ◽  
Fatty Acid Synthetase ◽  
Metabolic Effects ◽  
Zucker Rats ◽  
Obese Rats ◽  
Malic Enzyme Activity ◽  
Dhea Treatment

Dehydroepiandrosterone (DHEA) is a known noncompetitive inhibitor of glucose-6-phosphate dehydrogenase (G6PD). In the present investigation, the effects of chronic DHEA treatment on G6PD and several other enzymes involved in lipid metabolism were examined in lean and obese Zucker rats. Significant decreases in body weight were found in DHEA-treated rats in comparison with nontreated rats. In lean rats, DHEA treatment did not decrease either liver or adipose tissue G6PD and fatty acid synthetase activity, but malic enzyme activity was increased. In obese rats, decreased liver and adipose tissue G6PD and fatty acid synthetase activities were found. Malic enzyme activity in liver of obese DHEA rats was increased but not in adipose tissue. Adipose tissue lipoprotein lipase activity was decreased in both lean and obese DHEA rats. Serum insulin in obese DHEA rats was also decreased compared with control obese rats. These results indicate that the inhibition of G6PD may not be the mechanism of action of the antiobesity effect of DHEA. However, the metabolic effects of DHEA seen in obese rats may contribute to its antiobesity action.

RADIOACTIVE SUBSTRATE DISAPPEARANCE ASSAYS IN STEROID ENZYMOLOGY: THE EFFECTS OF PITUITARY TROPHINS AND OESTRADIOL ON THE FINAL STEPS OF ANDROGEN BIOSYNTHESIS

1967 ◽  
Vol 54 (1) ◽  
pp. 122-128 ◽  
Author(s):  
George I. Loutfi ◽  
Dwain D. Hagerman
Keyword(s):  
Enzyme Activity ◽  
Dehydrogenase Activity ◽  
Enzyme Preparation ◽  
Chronic Treatment ◽  
Marked Decrease ◽  
Steroid Metabolism ◽  
Rat Testis ◽  
Wide Applicability ◽  
Cleavage Enzyme ◽  
Radioactive Substrate

ABSTRACT An assessment of the feasibility and advantages of measurement of substrate disappearance for assays of enzyme activity in steroid metabolism was made, and the method was shown to be of wide applicability when certain conditions are met. The method was tested by application to the final steps of androgen biosynthesis by rat testis microsomes. and it was found that chronic treatment of the animal with large doses of LH prior to isolation of the enzyme preparation decreased the activity in this tissue of progesterone-17-hydroxylase, 17α-hydroxy-20-carbonyl cleavage enzyme and 17β-hydroxysteroid (testosterone) dehydrogenase. Oestradiol administration caused a less marked decrease in hydroxylase and dehydrogenase activity without effect on the cleavage enzyme, while FSH administration did not greatly alter the activity of these three enzymes. Chronic TSH administration gave results similar to those obtained with oestradiol.

The effect of grass or maize diet on plasma leptin and adipose tissue lipogenic enzyme activities in steers

2002 ◽  
Vol 2002 ◽  
pp. 94-94
Author(s):  
Y. Faulconnier ◽  
C. Delavaud ◽  
J. Fléchet ◽  
D. Dozias ◽  
R. Jailler ◽  
...  
Keyword(s):  
Body Weight ◽  
Adipose Tissue ◽  
Lipogenic Enzyme ◽  
Lipogenic Enzymes ◽  
Maize Silage ◽  
Marbling Score ◽  
Body Fatness ◽  
Adipose Tissues ◽  
Feeding Level ◽  
Plasma Leptin

Leptin is an important hormone for the control of food intake and body weight homeostasis in human and rodents. In ruminants, plasma leptin is positively related to body fatness and energy balance or feeding level (Chilliard et al., 2001) and linked to meat quality determinants such as marbling score (Minton et al., 1998). To our knowledge, no information is available on the effects of the nature of dietary forage on this parameter. The objective of the current work was to examine the effects of replacing maize silage with grass on plasma leptin as well as on the activities of five lipogenic enzymes in perirenal and inter-muscular adipose tissues (AT).

scholarly journals Clearing-factor lipase in muscle and adipose tissue of pigs

1973 ◽  
Vol 136 (2) ◽  
pp. 381-385 ◽  
Author(s):  
M. Enser
Keyword(s):  
Enzyme Activity ◽  
Adipose Tissue ◽  
Fatty Acid ◽  
Plasma Insulin ◽  
Subcutaneous Fat ◽  
Rapid Decrease ◽  
Plasma Fatty Acid ◽  
Plasma Insulin Concentration ◽  
Adipose Tissues ◽  
Perirenal Fat

1. Clearing-factor lipase was assayed in acetone–ether-dried powders of heart and adipose tissue of pigs. The enzyme activity in heart was higher than that in adipose tissue. The activity in the outer layer of subcutaneous fat was greater than that in the inner subcutaneous fat and the perirenal fat, which had similar activities. 2. Starvation for 48h, but not for 24h, decreased the activity of the heart enzyme. 3. Starvation for 24h caused a rapid decrease in the activity in all three adipose tissues, but even after 72h of starvation the activity was still highest in the outer subcutaneous fat. 4. Plasma fatty acid, glucose and insulin concentrations were determined in fed and starved pigs. Starvation decreased the plasma insulin concentration and increased the non-esterified fatty acid concentration.

scholarly journals Effects of chronic hyperinsulinaemia on hepatic enzymes involved in lipogenesis and carbohydrate metabolism in the young rat

1978 ◽  
Vol 172 (2) ◽  
pp. 327-331 ◽  
Author(s):  
K L McCormick ◽  
J A Widness ◽  
J B Susa ◽  
R Schwartz
Keyword(s):  
Pyruvate Kinase ◽  
Malic Enzyme ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Liver Weight ◽  
Hepatic Enzymes ◽  
Lower Blood Glucose ◽  
Lower Blood ◽  
Cleavage Enzyme ◽  
Young Rat ◽  
Blood Glucose Concentrations

Chronic (6 days) hyperinsulinaemia in young rats produced lower blood glucose concentrations and augmented body- and liver-weight gain. The insulin-treated rats had increased hepatic activities of citrate-cleavage enzyme, ‘malic’ enzyme and high-substrate (6.6 mM-phosphoenolpyruvate) pyruvate kinase, and decreased glucose 6-phosphatase. There were no changes in activities of phosphoenolpyruvate carboxykinase, phosphofructokinase, low-substrate (1.3 mM-phosphoenolpyruvate) pyruvate kinase, glucokinase and hexokinase.

The Effects of Catecholamines, Glucagon, and Diet on Enzyme Activities in Brown Fat and Liver of the Rat

1974 ◽  
Vol 52 (9) ◽  
pp. 739-743 ◽  
Author(s):  
Peter Hahn ◽  
Lorne T. Kirby
Keyword(s):  
Body Weight ◽  
Fatty Acid ◽  
Malic Enzyme ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Fatty Acid Synthetase ◽  
High Carbohydrate Diet ◽  
Brown Fat ◽  
Carbohydrate Diet ◽  
High Carbohydrate ◽  
Cleavage Enzyme

The effects of a high carbohydrate diet fed to young rats for 24–48 h on phosphoenolpyruvate carboxykinase, malic enzyme, citrate-cleavage enzyme, and fatty acid synthetase could be overcome by injecting the animals with glucagon (1 mg/100 g body weight) or norepinephrine (20 μg/100 g body weight) four times a day. The same effect was achieved with 50 mg ephedrine added to the 24 h diet. The catecholamines were more effective in brown fat, whereas glucagon seemed somewhat more effective in the liver.

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