scholarly journals Ethanol modulation of the hormonal and nutritional regulation of glucose 6-phosphate dehydrogenase activity in primary cultures of rat hepatocytes

1984 ◽  
Vol 217 (2) ◽  
pp. 543-549 ◽  
Author(s):  
D S Kelley ◽  
R F Kletzien
Keyword(s):  
Enzyme Activity ◽  
Primary Cultures ◽  
Rat Hepatocytes ◽  
Fold Increase ◽  
Defined Medium ◽  
Nutritional Regulation ◽  
G6pdh Activity ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Dose Dependent ◽  
Permissive Role

The hormonal and nutritional regulation of glucose 6-phosphate dehydrogenase (G6PDH; EC 1.1.1.49) was studied in primary cultures of rat hepatocytes maintained in a chemically defined medium. Inoculation of hepatocytes from starved rats into primary cultures resulted in a 4-5-fold increase in G6PDH activity in 48 h in the absence of hormones. Parallel cultures treated simultaneously with glucocorticoids and insulin exhibited a 12-15-fold increase during the same time. Glucocorticoids by themselves did not elevate G6PDH activity, whereas insulin alone significantly stimulated enzyme activity. Thus the glucocorticoids acted in a ‘permissive’ role to amplify the insulin stimulation of G6PDH. Elevated concentrations of glucose in the culture medium increased enzyme activity in both the control cultures and those treated with hormones. Ethanol was found to potentiate G6PDH activity in cultures treated with glucocorticoids and insulin. The effect of ethanol was time- and dose-dependent. These results establish that insulin, glucocorticoids, glucose and ethanol interact in some undefined manner to regulate hepatic G6PDH activity.

scholarly journals The effect of ethanol, alone and in combination with the glucocorticoids and insulin, on glucose-6-phosphate dehydrogenase synthesis and mRNA in primary cultures of hepatocytes

1985 ◽  
Vol 226 (1) ◽  
pp. 123-130 ◽  
Author(s):  
D J Stumpo ◽  
R F Kletzien
Keyword(s):  
Hormonal Regulation ◽  
Relative Rate ◽  
Primary Cultures ◽  
Fold Increase ◽  
Defined Medium ◽  
Enzyme Synthesis ◽  
Translation System ◽  
Adult Rat ◽  
Free Translation ◽  
Glucose 6 Phosphate Dehydrogenase

The hormonal regulation of the relative rate of synthesis and mRNA of glucose-6-phosphate dehydrogenase (G6PDH; EC 1.1.1.49) was studied in primary cultures of adult-rat liver parenchymal cells maintained in a chemically defined medium. Maintenance of hepatocytes from starved animals in a culture medium devoid of any hormones resulted in a 4-fold increase in the relative rate of G6PDH synthesis in 48 h. Parallel cultures treated with glucocorticoids alone exhibited a rate of G6PDH synthesis comparable with that in the control cultures, whereas insulin alone caused a 6.5-fold increase in the rate of synthesis in 48 h. However, if the cultures were treated with glucocorticoids and insulin simultaneously, a 13-fold increase in the rate of synthesis was observed. The effect of ethanol, alone and in combination with the hormones, on the relative rate of G6PDH synthesis was studied also. Ethanol alone caused an 8-fold increase in the rate of synthesis in 48 h, whereas the combination of ethanol, glucocorticoid and insulin caused a 25-fold increase. The amount of functional mRNA encoding G6PDH, as measured in a cell-free translation system, was compared with enzyme activity and relative rate of enzyme synthesis. The increases in G6PDH activity and relative rate of synthesis in primary cultures of hepatocytes treated with ethanol, alone and in combination with the glucocorticoids and insulin, were paralleled by comparable increases in G6PDH mRNA. The results of this study show that the glucocorticoids acted in a permissive manner to amplify the insulin stimulation of G6PDH synthesis and that insulin, glucocorticoids and ethanol interact to stimulate synthesis of G6PDH primarily by increasing the concentration of functional G6PDH mRNA.

scholarly journals Glucose-6-phosphate dehydrogenase mRNA sequence abundance in primary cultures of rat hepatocytes. Effect of insulin and dexamethasone

1986 ◽  
Vol 237 (2) ◽  
pp. 617-619 ◽  
Author(s):  
R S Fritz ◽  
D J Stumpo ◽  
R F Kletzien
Keyword(s):  
Blot Hybridization ◽  
Primary Cultures ◽  
Rat Hepatocytes ◽  
Nutritional Regulation ◽  
Dot Blot ◽  
Hybridization Procedure ◽  
Hepatic Glucose ◽  
Glucose 6 Phosphate Dehydrogenase

Hepatic glucose-6-phosphate dehydrogenase (G6PDH; EC 1.1.1.49) is subject to nutritional regulation. To assess the possible role of hormones in this regulation, the amounts of G6PDH mRNA were studied in primary cultures of rat hepatocytes treated with insulin and dexamethasone, alone or in combination. Relative concentrations of G6PDH mRNA were directly assessed by a dot-blot hybridization procedure with nick-translated cDNA probes. G6PDH sequence abundance increased when the cultures were treated with insulin or dexamethasone, but the G6PDH mRNA induced by dexamethasone was not expressed at the protein level as active enzyme. In cultures treated with insulin and dexamethasone in combination, enzyme activity and G6PDH sequence abundance were greater than those induced by insulin alone. Our results directly demonstrate that G6PDH mRNA amounts are modulated in liver by these two classes of hormones and can partially account for the dietary induction of the enzyme observed in vivo.

Paradoxical effect of perchlorate on thyroidal weight, glucose 6-phosphate dehydrogenase and polyamines in methylthiouracil-treated rats

1981 ◽  
Vol 97 (4) ◽  
pp. 491-495 ◽  
Author(s):  
S. Matsuzaki ◽  
M. Suzuki
Keyword(s):  
Enzyme Activity ◽  
Control Level ◽  
Sodium Perchlorate ◽  
Inhibitory Effect ◽  
Paradoxical Effect ◽  
G6pdh Activity ◽  
Wet Weight ◽  
Glucose 6 Phosphate Dehydrogenase

Abstract. The effect of sodium perchlorate (NaClO4) on the methylthiouracil-induced increase in the activity of thyroid glucose 6-phosphate dehydrogenase (G6PDH), ornithine decarboxylase (ODC) and polyamine contents was studied in the rat. The G6PDH activity was increased nearly three-fold by methylthiouracil (MTU) but not by ClO4- at 7 days of treatment. Perchlorate lowered the MTU-induced enzyme activity to nearly the control level, without changing circulating thyrotrophin (TSH). The anion had no inhibitory effect on G6PDH activity in vitro. The possibility that an inhibitor specific for G6PDH was generated in ClO4- treated rat thyroids was excluded. The activity of ODC was greatly increased by both ClO4- and MTU, the increase being significant as early as on the second day of treatment. Perchlorate had no inhibitory effect on MTU-induced ODC activity in vivo but decreased total contents of spermidine and spermine in the thyroid, without affecting the concentration (nmoles/ g wet weight) of the polyamines. These results suggest that ClO4- acts directly on the thyroid to suppress specifically the stimulatory effect of TSH on G6PDH activity and possibly on polyamine accumulation.

scholarly journals The enzymes of the glycolytic pathway in erythrocytes infected with Plasmodium falciparum malaria parasites

Blood ◽  
1988 ◽  
Vol 72 (6) ◽  
pp. 1922-1925 ◽  
Author(s):  
EF Jr Roth ◽  
MC Calvin ◽  
I Max-Audit ◽  
J Rosa ◽  
R Rosa
Keyword(s):  
Plasmodium Falciparum ◽  
Enzyme Activity ◽  
Adenylate Kinase ◽  
Genetic Basis ◽  
Glucose Consumption ◽  
Fold Increase ◽  
Plasmodium Falciparum Malaria ◽  
Red Cells ◽  
Glycolytic Pathway ◽  
Glucose 6 Phosphate Dehydrogenase

Abstract Enzymes of the glycolytic pathway as well as some ancillary enzymes were studied in normal red cells parasitized with Plasmodium falciparum in culture at varying parasitemias as well as in isolated parasites. The levels of all enzymes except diphosphoglycerate mutase, glucose-6- phosphate dehydrogenase, and adenylate kinase were elevated. Extreme elevations of hexokinase, aldolase, enolase, pyruvate kinase, and adenosine deaminase concentrations were noted. In most cases, electrophoretically distinct bands of enzyme activity were also seen. These findings partly explain the previously noted 50- to 100-fold increase in glucose consumption of infected red cells and suggest that further knowledge of these parasite enzymes and their genetic basis may aid both in designing new chemotherapy and in understanding the evolution of these parasites.

scholarly journals Stimulatory effect of the intestinal peptide PHI on glycogenolysis and gluconeogenesis in isolated rat hepatocytes

1983 ◽  
Vol 214 (3) ◽  
pp. 999-1002 ◽  
Author(s):  
J E Felíu ◽  
J Marco
Keyword(s):  
Cyclic Amp ◽  
Pyruvate Kinase ◽  
Glycogen Phosphorylase ◽  
Rat Hepatocytes ◽  
Fold Increase ◽  
Isolated Rat Hepatocytes ◽  
Mediated Effects ◽  
Dose Dependent ◽  
Isolated Rat ◽  
Stimulation Of

The newly isolated peptide PHI provoked a dose-dependent stimulation of glycogenolysis and gluconeogenesis in isolated rat hepatocytes; at 1 microM-PHI, both processes were increased 1.6-fold as compared with basal values. These PHI-mediated effects were accompanied by the activation of glycogen phosphorylase and the inactivation of pyruvate kinase. PHI (1 microM) also caused a 2-fold increase in hepatocyte cyclic AMP.

scholarly journals The enzymes of the glycolytic pathway in erythrocytes infected with Plasmodium falciparum malaria parasites

Blood ◽  
1988 ◽  
Vol 72 (6) ◽  
pp. 1922-1925
Author(s):  
EF Jr Roth ◽  
MC Calvin ◽  
I Max-Audit ◽  
J Rosa ◽  
R Rosa
Keyword(s):  
Plasmodium Falciparum ◽  
Enzyme Activity ◽  
Adenylate Kinase ◽  
Genetic Basis ◽  
Glucose Consumption ◽  
Fold Increase ◽  
Plasmodium Falciparum Malaria ◽  
Red Cells ◽  
Glycolytic Pathway ◽  
Glucose 6 Phosphate Dehydrogenase

Enzymes of the glycolytic pathway as well as some ancillary enzymes were studied in normal red cells parasitized with Plasmodium falciparum in culture at varying parasitemias as well as in isolated parasites. The levels of all enzymes except diphosphoglycerate mutase, glucose-6- phosphate dehydrogenase, and adenylate kinase were elevated. Extreme elevations of hexokinase, aldolase, enolase, pyruvate kinase, and adenosine deaminase concentrations were noted. In most cases, electrophoretically distinct bands of enzyme activity were also seen. These findings partly explain the previously noted 50- to 100-fold increase in glucose consumption of infected red cells and suggest that further knowledge of these parasite enzymes and their genetic basis may aid both in designing new chemotherapy and in understanding the evolution of these parasites.

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