THE INFLUENCE OF ADRENALECTOMY UPON THE ACTIVITY OF THE HEXOSEMONOPHOSPHATE SHUNT IN THE LIVERS AND MAMMARY GLANDS OF LACTATING RATS

1960 ◽  
Vol 38 (1) ◽  
pp. 1265-1273 ◽  
Author(s):  
J. S. Willmer
Keyword(s):  
Enzyme Activity ◽  
Considerable Increase ◽  
Mammary Glands ◽  
Mammary Tissue ◽  
Hepatic Tissue ◽  
Phosphogluconate Dehydrogenase ◽  
Growth Changes ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Adrenalectomized Rats ◽  
Hepatic Level

The development of the hexosemonophosphate shunt in mammary tissue and liver of lactating rats has been studied. A sixfold increase in mammary glucose-6-phosphate dehydrogenase levels between parturition and weaning was accompanied by a considerable increase in 6-phosphogluconate dehydrogenase activity. The hepatic level of the former enzyme was also elevated 11-fold during this period. Adrenalectomy at parturition, or on the 3rd, 6th, 9th, or 14th days of lactation, depressed the activity of this pathway in mammary gland, a lowered level being observed in all cases after operation. A slight increase in enzyme activity was found in hepatic tissue in the immediate postoperative period; this was succeeded by a decrease.These results are discussed in relation to the growth changes observed in groups of unoperated and adrenalectomized rats.

THE INFLUENCE OF ADRENALECTOMY UPON THE ACTIVITY OF THE HEXOSEMONOPHOSPHATE SHUNT IN THE LIVERS AND MAMMARY GLANDS OF LACTATING RATS

1960 ◽  
Vol 38 (11) ◽  
pp. 1265-1273 ◽  
Author(s):  
J. S. Willmer
Keyword(s):  
Enzyme Activity ◽  
Considerable Increase ◽  
Mammary Glands ◽  
Mammary Tissue ◽  
Hepatic Tissue ◽  
Phosphogluconate Dehydrogenase ◽  
Growth Changes ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Adrenalectomized Rats ◽  
Hepatic Level

The development of the hexosemonophosphate shunt in mammary tissue and liver of lactating rats has been studied. A sixfold increase in mammary glucose-6-phosphate dehydrogenase levels between parturition and weaning was accompanied by a considerable increase in 6-phosphogluconate dehydrogenase activity. The hepatic level of the former enzyme was also elevated 11-fold during this period. Adrenalectomy at parturition, or on the 3rd, 6th, 9th, or 14th days of lactation, depressed the activity of this pathway in mammary gland, a lowered level being observed in all cases after operation. A slight increase in enzyme activity was found in hepatic tissue in the immediate postoperative period; this was succeeded by a decrease.These results are discussed in relation to the growth changes observed in groups of unoperated and adrenalectomized rats.

EFFECTS OF TESTOSTERONE PROPIONATE AND CYPROTERONE ACETATE ON CARBOHYDRATE METABOLISM IN RAT MAMMARY GLANDS

1980 ◽  
Vol 84 (3) ◽  
pp. 467-471
Author(s):  
N. DESHPANDE ◽  
IRENE MITCHELL
Keyword(s):  
Carbohydrate Metabolism ◽  
Cyproterone Acetate ◽  
Testosterone Propionate ◽  
Mammary Glands ◽  
Normal Mammary Gland ◽  
Inhibitory Effects ◽  
Phosphogluconate Dehydrogenase ◽  
Normal Rat ◽  
And Function ◽  
Glucose 6 Phosphate Dehydrogenase

The effects of administration of testosterone propionate on the activities of seven of the enzymes of carbohydrate metabolism in normal rat mammary glands were investigated and the validity of the results was confirmed by simultaneous injection of the hormone and cyproterone acetate. The administration of the androgen increased the activities of phosphofructokinase (PFK), glucose-6-phosphate dehydrogenase (G6PDH), 6-phosphogluconate dehydrogenase (6PGDH) and lactate dehydrogenase (LDH) in glands from both intact and from ovariectomized and adrenalectomized animals. Administration of cyproterone acetate alone resulted in a significant reduction in the activities of PFK and G6PDH and when given together with the androgen it inhibited increases in the activities of PFK, G6PDH, 6PGDH and LDH induced by testosterone. It was concluded that these results did not explain the known inhibitory effects of the androgen on normal mammary gland growth and function.

Effects of exercise, detraining, starvation, and refeeding on lipogenic capacity of Osborne-Mendel rat

1988 ◽  
Vol 254 (4) ◽  
pp. R648-R654
Author(s):  
P. Lowney ◽  
V. M. Lee ◽  
R. J. Hansen ◽  
J. S. Stern
Keyword(s):  
Enzyme Activity ◽  
Plasma Glucose ◽  
Liver Lipid ◽  
Liver Triglyceride ◽  
Phosphogluconate Dehydrogenase ◽  
Hepatic Glucose ◽  
Liver Triglycerides ◽  
Lipid Stores ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Final Speed

Both starvation and refeeding and exercise and detraining are procedures that result in lowered lipid stores followed by their refilling. Rats subjected to these procedures were evaluated for their ability to produce hepatic biosynthetic reducing equivalents. Five-week-old male Osborne-Mendel rats were exercised on a motorized treadmill for 6 wk (final speed 27 m/min, 60 min/day, 6 day/wk) or kept sedentary. Exercised and sedentary rats were starved for 48 h or fed ad libitum. After treatments, some rats in each group were killed. Remaining exercised animals were detrained or detrained and refed. Remaining sedentary rats were refed. Activities of hepatic glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, and malic enzyme were evaluated. Plasma glucose, triglyceride, insulin, liver triglyceride, and body composition were determined. Results indicate that changes in lipids stores associated with starvation and refeeding and exercise and detraining are not associated with similar changes in enzyme activity. Starvation resulted in lowered plasma glucose, triglyceride, and insulin. Starvation and all exercise treatments resulted in lowered carcass fat. Exercised rats who were starved for 48 h and then detrained and refed for 72 h had the greatest liver weights and percent liver triglycerides. This was not associated with similar changes in enzyme activity. Increased liver lipid and decreased carcass fat may indicate a redistribution of lipid stores in these animals.

scholarly journals The pentose phosphate pathway of glucose metabolism. Hormonal and dietary control of the oxidative and non-oxidative reactions of the cycle in liver

1969 ◽  
Vol 111 (5) ◽  
pp. 713-725 ◽  
Author(s):  
F. Novello ◽  
J. A. Gumaa ◽  
Patricia McLean
Keyword(s):  
Diabetic Rats ◽  
Pentose Phosphate ◽  
Hexokinase Activity ◽  
Transketolase Activity ◽  
Control Value ◽  
Phosphogluconate Dehydrogenase ◽  
Pentose Phosphate Cycle ◽  
Oxidative Reactions ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Adrenalectomized Rats

1. Measurements were made of the non-oxidative reactions of the pentose phosphate cycle in liver (transketolase, transaldolase, ribulose 5-phosphate epimerase and ribose 5-phosphate isomerase activities) in a variety of hormonal and nutritional conditions. In addition, glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase activities were measured for comparison with the oxidative reactions of the cycle; hexokinase, glucokinase and phosphoglucose isomerase activities were also included. Starvation for 2 days caused significant lowering of activity of all the enzymes of the pentose phosphate cycle based on activity in the whole liver. Re-feeding with a high-carbohydrate diet restored all the enzyme activities to the range of the control values with the exception of that of glucose 6-phosphate dehydrogenase, which showed the well-known ‘overshoot’ effect. Re-feeding with a high-fat diet also restored the activities of all the enzymes of the pentose phosphate cycle and of hexokinase; glucokinase activity alone remained unchanged. Expressed as units/g. of liver or units/mg. of protein hexokinase, glucose 6-phosphate dehydrogenase, transketolase and pentose phosphate isomerase activities were unchanged by starvation; both 6-phosphogluconate dehydrogenase and ribulose 5-phosphate epimerase activities decreased faster than the liver weight or protein content. 2. Alloxan-diabetes resulted in a decrease of approx. 30–40% in the activities of 6-phosphogluconate dehydrogenase, ribose 5-phosphate isomerase, ribulose 5-phosphate epimerase and transketolase; in contrast with this glucose 6-phosphate dehydrogenase, transaldolase and phosphoglucose isomerase activities were unchanged. Treatment of alloxan-diabetic rats with protamine–zinc–insulin for 3 days caused a very marked increase to above normal levels of activity in all the enzymes of the pentose phosphate pathway except ribulose 5-phosphate epimerase, which was restored to the control value. Hexokinase activity was also raised by this treatment. After 7 days treatment of alloxan-diabetic rats with protamine–zinc–insulin the enzyme activities returned towards the control values. 3. In adrenalectomized rats the two most important changes were the rise in hexokinase activity and the fall in transketolase activity; in addition, ribulose 5-phosphate epimerase activity was also decreased. These effects were reversed by cortisone treatment. In addition, in cortisone-treated adrenalectomized rats glucokinase activity was significantly lower than the control value. 4. In thyroidectomized rats both ribose 5-phosphate isomerase and transketolase activities were decreased; in contrast with this transaldolase activity did not change significantly. Hypophysectomy caused a 50% fall in transketolase activity that was partially reversed by treatment with thyroxine and almost fully reversed by treatment with growth hormone for 8 days. 5. The results are discussed in relation to the hormonal control of the non-oxidative reactions of the pentose phosphate cycle, the marked changes in transketolase activity being particularly outstanding.

The induction by exogenous hormones of enzymes metabolising glucose 6-phosphate in the mammary gland of the pseudopregnant rabbit

1969 ◽  
Vol 36 (1) ◽  
pp. 47-52 ◽  
Author(s):  
R. J. Heitzman
Keyword(s):  
Enzyme Activity ◽  
Mammary Gland ◽  
Enzyme Activities ◽  
Synergistic Action ◽  
Phosphate Metabolism ◽  
Exogenous Hormones ◽  
Phosphogluconate Dehydrogenase ◽  
Intraductal Injection ◽  
Glucose 6 Phosphate Dehydrogenase

SummaryA study was made of the effects of the hormones, prolactin and cortisol acetate, on the activities in the mammary gland of the pseudopregnant rabbit of the enzymes concerned with lactose biosynthesis and glucose 6-phosphate metabolism, namely: UDP-glucose pyrophosphorylase, UDP-glucose-4'-epimerase, phosphofructokinase, phosphoglucomutase, glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase. Significant increases in enzyme activities were observed in rabbits examined 3 or 4 days after receiving a mammary intraductal injection of prolactin. The activities were not significantly increased at examination 2 days after injection of prolactin. Rabbits receiving cortisol acetate each day for 3 days also showed no significant increases in mammary enzyme activity. However, when prolactin and cortisol acetate were given simultaneously over a period of 3 days, increased enzyme activities were found suggesting synergistic action of the hormones.

Estimations of Rates of Synthesis and Degradation of Several Rat Mammary Gland Enzymes from Changes in Enzyme Activities

1972 ◽  
Vol 50 (4) ◽  
pp. 386-391 ◽  
Author(s):  
G. O. Korsrud ◽  
R. L. Baldwin
Keyword(s):  
Fatty Acid ◽  
Malic Enzyme ◽  
Fatty Acid Synthetase ◽  
Mammary Glands ◽  
Phosphogluconate Dehydrogenase ◽  
Udpglucose Pyrophosphorylase ◽  
Cleavage Enzyme ◽  
Rat Mammary Gland ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Synthesis And Degradation

Based upon rates of decrease in the activities of citrate cleavage enzyme (EC 4.1.3.7), malic enzyme (EC 1.1.1.40), fatty acid synthetase, UDPglucose pyrophosphorylase (EC 2.7.7.9), UDPglucose 4-epimerase (EC 5.1.3.3), and glucose-6-phosphate dehydrogenase (EC 1.1.1.49) in rat mammary glands after adrenalectomy–ovariectomy on the 11th day of lactation, the half-lives of the enzymes were estimated to be 28, 31, 28, 50, 20, and 24 h, respectively. The half-life estimates for UDPglucose pyrophosphorylase and glucose-6-phosphate dehydrogenase compared favorably with previous estimates of 35 and 20 h, respectively, obtained in rats 5 days postpartum utilizing specific immunological techniques. In a second experiment, increases in the activities of enzymes in adrenalectomized, lactating rats after initiation of cortisol therapy were investigated. Rats were adrenalectomized on the 5th day of lactation and cortisol therapy was started 5 days later. The estimated half-lives for citrate cleavage enzyme, malic enzyme, fatty acid synthetase, UDPglucose pyrophosphorylase, UDPglucose 4-epimerase, the A protein of the lactose synthetase complex, glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase (EC 1.1.1.44), and hexokinase (EC 2.7.1.1) were, respectively, 84, 60, 92, 76, 170, 102, 79, 88, and 81 h.

scholarly journals Kinetic Behaviour of Glucose 6-Phosphate Dehydrogenase and 6-Phosphogluconate Dehydrogenase in Different Tissues of Rainbow Trout (Oncorhynchus mykiss) Exposed to Non-Lethal Concentrations of Cadmium

2009 ◽  
Vol 78 (1) ◽  
pp. 179-185 ◽  
Author(s):  
Olcay Hisar ◽  
Adem Yavuz Sönmez ◽  
Şükrü Beydemir ◽  
Şükriye Aras Hisar ◽  
Telat Yanik ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Dose Response ◽  
Enzyme Activities ◽  
Response Pattern ◽  
Base Line ◽  
Phosphogluconate Dehydrogenase ◽  
Liver And Kidney ◽  
Glucose 6 Phosphate Dehydrogenase

The effects of cadmium (Cd) on the enzymatic activities of glucose 6-phosphate dehydrogenase (G6PD) and 6-phosphogluconate dehydrogenase (6PGD) were investigated in the gill, liver and kidney tissues of rainbow trout (Oncorhynchus mykiss). Three test groups of fish were subjected to increasing concentrations (1, 3 and 5 mg/l) of cadmium (Cd) in vivo, respectively. The G6PD and 6PGD activities in the gill, liver, and kidney tissues of each group of fish were measured on days 1, 3, 5 and 7. G6PD and 6PGD enzyme activities, measured in gill, liver and kidney homogenates, were stimulated by various concentrations (1, 3, and 5 mg/l) of cadmium. Although the dose-response pattern of G6PD enzyme activities in liver and kidney tissue was very similar, that in gill was different from both other tissues. The enzyme activity of G6PD enzyme was significantly stimulated after three days (Day 3) in liver and kidney tissues at a dose of 1 mg/l Cd (p < 0.05), whereas it was stimulated on the first day of experiment (Day 1) in gill, liver and kidney tissues at doses of 3 and 5 mg/l Cd (p < 0.05). However, the activity of 6PGD was stimulated after three days (Day 3) in the liver at a dose of 1 mg/l Cd (p < 0.05) and on the first day in gill, liver and kidney tissues at doses of 3 and 5 mg/l Cd (p < 0.05). The stimulation effect of the 5 mg/l dose of Cd on G6PD and 6PGD enzyme activities was significantly diminished after seven days (Day 7) in all tissues (p < 0.05). In contrast to the dose-response pattern at the dose of 5 mg/l Cd, G6PD and 6PGD enzyme activities were stimulated significantly (p < 0.05) in liver and kidney tissues at the doses of 3 and 1 mg/l Cd. The stimulation effect of cadmium on the three tissues studied was also calculated; for both of the enzymes (G6PD and 6PGD), the enzyme activity levels were stimulated by approximately 60% and 38% in gills, 68% and 44% in liver, and 67% and 41% in kidneys, respectively, over the base-line enzyme activity of the control groups during the sevenday experimental period. These findings indicate that tissue G6PD and 6PGD enzymes function to protect against cadmium toxicity.

scholarly journals Effect of thyroidectomy on pathways of glucose metabolism in lactating rat mammary gland

1967 ◽  
Vol 105 (2) ◽  
pp. 615-623 ◽  
Author(s):  
Eileen Walters ◽  
Patricia McLean
Keyword(s):  
Mammary Gland ◽  
Glucose Oxidation ◽  
Mammary Tissue ◽  
Control Group ◽  
Phosphogluconate Dehydrogenase ◽  
Lactating Mammary Gland ◽  
Cleavage Enzyme ◽  
Rat Mammary Gland ◽  
Group 3 ◽  
Glucose 6 Phosphate Dehydrogenase

1. Assessment of the overall metabolic changes in lactating mammary gland after thyroidectomy has been made by measurement of the incorporation of 14C from specifically labelled glucose, pyruvate and acetate into 14CO2 and 14C-labelled lipid in the experimental rats and in sham-operated control animals. 2. Thyroidectomy depressed the oxidation of 14C-labelled substrates, an effect still apparent when the control rats were pair-fed with thyroidectomized rats; however, the ratio of oxidation of [1−14C]glucose/oxidation of [6−14C]glucose was unaltered. In parallel with these studies it was revealed that the activities of hexokinase, glucose 6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase and NADP-linked isocitrate dehydrogenase were all lower in the thyroidectomized group than in the pair-fed control group. 3. Thyroidectomy also lowered the incorporation of 14C-labelled substrates into 14C-labelled lipid, an effect further studied by measurement of the activities of citrate-cleavage enzyme and acetate thiokinase. Restricting the food intake of the control rats to that of the thyroidectomized group lowered the activity of citrate-cleavage enzyme, but no further depression was observed on thyroidectomy. The oxidized and reduced nicotinamide nucleotide content of mammary tissue was shown to be decreased in the thyroidectomized rats compared with the control rats.

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