Prolactin, Thyrotrophin Interaction in the Regulation of Glucose-6-Phosphate Dehydrogenase and 6-Phosphogluconate Dehydrogenase Activities in Rat Mammary Glands

1980 ◽  
Vol 12 (6) ◽  
pp. 333-339 ◽  
Author(s):  
N. Deshpande ◽  
Irene Mitchell
Keyword(s):  
Mammary Glands ◽  
Phosphogluconate Dehydrogenase ◽  
Glucose 6 Phosphate Dehydrogenase

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.

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.

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.

Effects of Adrenalectomy, Adrenalectomy–Ovariectomy, and Cortisol and Estrogen Therapies Upon Enzyme Activities in Lactating Rat Mammary Glands

1972 ◽  
Vol 50 (4) ◽  
pp. 366-376 ◽  
Author(s):  
G. O. Korsrud ◽  
R. L. Baldwin
Keyword(s):  
Pyruvate Kinase ◽  
Enzyme Activities ◽  
Secretory Cell ◽  
Succinic Dehydrogenase ◽  
Mammary Glands ◽  
Pentose Phosphate ◽  
Phosphogluconate Dehydrogenase ◽  
Udpglucose Pyrophosphorylase ◽  
Cleavage Enzyme ◽  
Glucose 6 Phosphate Dehydrogenase

The effects of adrenalectomy and adrenalectomy–ovariectomy on the 5th day of lactation followed by cortisol and estrogen therapies on enzyme activities in rat mammary glands were investigated. This stage of lactation was selected because mammary secretory cell proliferation is essentially complete at this time thereby enabling study of the effects of cortisol and estrogen on enzyme levels in a nonproliferating secretory cell population. Eighteen enzymes were selected for study on the bases of their respective roles in milk biosynthesis and carbohydrate and energy metabolism and/or on the basis of previous studies indicating that their activities increase during midlactation or are regulated, in part, by steroid hormones. After adrenalectomy on the 5th day of lactation, cortisol therapy was required for normal increases in the activities of succinic dehydrogenase, citrate cleavage enzyme, malic enzyme, UDPglucose pyrophosphorylase, UDPglucose 4-epimerase, and glucose-6-phosphate dehydrogenase. The activities of UDPglucose pyrophosphorylase and glucose-6-phosphate dehydrogenase were higher than normal in cortisol-treated animals. Cortisol therapy during the last 2 days of the experiment increased the activity of UDPglucose pyrophosphorylase and possibly citrate cleavage enzyme. The activities of α-glycerolphosphate dehydrogenase, phosphoglucomutase, 6-phosphogluconate dehydrogenase, pentose phosphate metabolizing ability, hexokinase, phosphofructokinase, fructose-1,6-diphosphate aldolase, pyruvate kinase, lactic dehydrogenase, aspartate aminotransferase, isocitrate dehydrogenase, and extramitochondrial malate dehydrogenase were not notably affected by adrenalectomy or cortisol therapy. The activities of 6-phosphogluconate dehydrogenase, pentose phosphate metabolizing ability, phosphofructokinase, and pyruvate kinase may have increased after the 5th day of lactation in adrenalectomized as well as in normal animals. Combining ovariectomy with adrenalectomy reduced pup weight gains more than adrenalectomy alone, but did not further decrease significantly the activities of any of the enzymes measured. Ovariectomy had no effect when cortisol was administered. Cortisol therapy completely reversed adverse effects of estrogen given to adrenalectomized–ovariectomized animals. On the bases of these and previous data, it was concluded that cortisol regulates the rates of synthesis of several mammary gland enzymes during midlactation.

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