DIFFERENCES IN THE AGE-DEPENDENT DEVELOPMENT AND SEXUAL DIFFERENTIATION OF SOLUBLE AND MEMBRANE-BOUND ACTIVITIES OF 3α- and 3β-HYDROXYSTEROID-DEHYDROGENASE IN RAT LIVER

1973 ◽  
Vol 71 (4_Suppl) ◽  
pp. S135
Author(s):  
H.-G. Hoff ◽  
H. Schriefers
Keyword(s):  
Rat Liver ◽  
Sexual Differentiation ◽  
Hydroxysteroid Dehydrogenase ◽  
Dependent Development ◽  
Age Dependent ◽  
Membrane Bound

ORGAN-SPECIFIC ONTOGENESES OF STEROID HORMONE METABOLIZING ENZYME ACTIVITIES IN THE RAT

1975 ◽  
Vol 79 (1) ◽  
pp. 192-201 ◽  
Author(s):  
Rüdiger Ghraf ◽  
Ulrich Vetter ◽  
Jeane Marie Zandveld ◽  
Herbert Schriefers
Keyword(s):  
Enzyme Activity ◽  
Sexual Differentiation ◽  
Microsomal Fraction ◽  
Steroid Hormone ◽  
Hydroxysteroid Dehydrogenase ◽  
Dependent Development ◽  
Enzymes Activities ◽  
Age Dependent ◽  
Organ Specific ◽  
Liver And Kidney

ABSTRACT The development and sexual differentiation of 11β- and 17β-hydroxysteroid dehydrogenase activities was investigated in the liver, kidney, adrenal and gonads of rats over a period of 15–120 days of life. 11β-Hydroxysteroid dehydrogenase in the adrenal and ovary was at the limit of detectibility at all the stages of life investigated. In the liver, kidney and testis the enzyme activity is restricted to the microsomal fraction and demonstrates an age-dependent development; in the liver, kidney and in the gonads it is additionally characterized by a sexual differentiation to higher values in the male sex. In all the organs investigated the cytoplasmic and microsomal fractions contain 17β-hydroxysteroid dehydrogenase activity; the activities are very low in the microsomal fraction of the kidney and in the cytosol of the testis. In all the organs the enzyme activity of at least one cell fraction displays an age-dependent development. The only activities, not demonstrating an ontogenesis are those of the cytosol of the adrenal and those of the microsomal fraction of the kidney. The age-dependent development is accompanied by a sexual differentiation of the enzymes activities. The only exception is the microsomal activity of the liver. The female sex shows the higher activity in the kidney, adrenal and gonads; whereas the male animal shows the higher activity only in the cytosol of the liver. The developmental processes of 11β- and 17β-hydroxysteroid dehydrogenase have the following properties in common: In the immature phase (day 15–30) the activities of the enzymes develop either very rapidly to manifold higher values or remain constant at the low neonatal level; no sexual differentiation of the enzymes activities occurs at this stage of life. The rapid increase in activity is found only in the liver and kidney, that is in the steroid hormone catabolizing organs. It does not occur in the steroid hormone producing glands.

REGULATION OF THE ACTIVITIES OF THE ENZYMES INVOLVED IN THE METABOLISM OF STEROID HORMONES IN RAT LIVER: THE EFFECT OF 19-NORTESTOSTERONE AND THE INFLUENCE OF CYPROTERONE ACETATE ON THE ACTION OF TESTOSTERONE AND 5α-DIHYDROTESTOSTERONE

1974 ◽  
Vol 77 (2) ◽  
pp. 287-297 ◽  
Author(s):  
Rüdiger Ghraf ◽  
Edmund Rodney Lax ◽  
Hanns-Georg Hoff ◽  
Herbert Schriefers
Keyword(s):  
Weight Loss ◽  
Body Weight ◽  
Rat Liver ◽  
Enzyme Activities ◽  
Cyproterone Acetate ◽  
Hydroxysteroid Dehydrogenase ◽  
Seminal Vesicles ◽  
Normal Male ◽  
Steroid Hydroxylases ◽  
Drug Leads

ABSTRACT The androgens testosterone and 5α-dihydrotestosterone, the anabolic drug 19-nortestosterone and the anti-androgen cyproterone acetate were investigated with regard to their modifying action on the sexual differentiation of the activities of rat liver enzymes involved in steroid hormone metabolism. The activities of the enzymes (Δ4-5α-hydrogenase, 20-ketoreductase, 3α-and 3β-hydroxysteroid dehydrogenase, NAD- and NADP-dependent Δ4-3β-hydroxysteroid dehydrogenase, total steroid hydroxylases, 7α- and 16α-hydroxylase) were determined in cell-free liver fractions of male animals castrated on day 25 of life and killed on day 90; and of castrated animals which, from day 75 to 89 received daily sc injections (0.3 mg/100 g body weight) of the anabolic drug or the androgen only or in combination with cyproterone acetate (3 mg/100 g body weight). With the exception of 7α-hydroxylase castration leads to a feminization of the enzyme activity pattern. However, the degree of feminization varies from enzyme to enzyme. The administration of testosterone or of 5α-dihydrotestosterone reverses the effect of castration. With 5α-dihydrotestosterone activity values were reached which in some cases were significantly higher than those obtained with testosterone. Although both androgens restored the enzyme activities to the normal male values, neither androgen was able to compensate for the weight loss of the seminal vesicles in the dose administered. The administration of 19-nortestosterone in the same dose as testosterone is only 30 % as effective in restoring the weight loss of the seminal vesicles, but leads to identical activities of Δ4-5α-hydrogenase and of hydroxysteroid dehydrogenases as are found for testosterone. 19-Nortestosterone is without influence on the activities of total steroid hydroxylases and of 16α-hydroxylase. 16α-Hydroxylase is the only enzyme in which the activity enhancing effects of testosterone or of 5α-dihydrotestosterone can be completely blocked by the simultaneous administration of the anti-androgen cyproterone acetate. In all other enzyme activities the anti-androgen does not interfere with the effect of the androgens although it blocks their action on the weight restitution of the seminal vesicles by 60–70 %. 7α-Hydroxylase does not exhibit any androgen dependency. Neither castration nor the subsequent administration of the two androgens, or of the anabolic drug leads to any alterations in activity. However, it is interesting to note that the administration of cyproterone acetate does cause an increase in activity.

scholarly journals Contamination of free-ribosome fractions by detached previously membrane-bound ribosomes (Short Communication)

1974 ◽  
Vol 138 (2) ◽  
pp. 305-307 ◽  
Author(s):  
K. O'Toole
Keyword(s):  
Rat Liver ◽  
Membrane Fraction ◽  
Short Communication ◽  
Free Ribosome ◽  
Membrane Bound ◽  
Free Polyribosome

A rough-membrane fraction isolated from rat liver by a procedure designed to prevent membrane denaturation was subjected to the gradient treatment normally used to isolate free ribosomes. Under these conditions, at most 20% of the ribosomes were detached from membrane with less than 5% sedimenting into the free-polyribosome pellet.

Quinone reduction and redox cycling catalysed by purified rat liver dihydrodiol/ 3α-hydroxysteroid dehydrogenase

1992 ◽  
Vol 44 (2) ◽  
pp. 341-349 ◽  
Author(s):  
Jochen Klein ◽  
Karin Post ◽  
Albrecht Seidel ◽  
Heinz Frank ◽  
Franz Oesch ◽  
...  
Keyword(s):  
Rat Liver ◽  
Hydroxysteroid Dehydrogenase ◽  
Redox Cycling ◽  
Quinone Reduction

Ferritin Synthesis by Free and Membrane-Bound (Poly)ribosomes of Rat Liver

1971 ◽  
Vol 138 (2) ◽  
pp. 399-403 ◽  
Author(s):  
D. G. Puro ◽  
G. W. Richter
Keyword(s):  
Rat Liver ◽  
Ferritin Synthesis ◽  
Membrane Bound

'Liver-type' 11β-hydroxysteroid dehydrogenase cDNA encodes reductase but not dehydrogenase activity in intact mammalian COS-7 cells

1994 ◽  
Vol 13 (2) ◽  
pp. 167-174 ◽  
Author(s):  
S C Low ◽  
K E Chapman ◽  
C R W Edwards ◽  
J R Seckl
Keyword(s):  
Dehydrogenase Activity ◽  
Rat Liver ◽  
Mammalian Cells ◽  
Reductase Activity ◽  
Hydroxysteroid Dehydrogenase ◽  
Luciferase Reporter ◽  
Luciferase Expression ◽  
Intact Cells ◽  
Mmtv Ltr

ABSTRACT 11β-Hydroxysteroid dehydrogenase (11β-HSD) catalyses the metabolism of corticosterone to inert 11-dehydrocorticosterone, thus preventing glucocorticoid access to otherwise non-selective renal mineralocorticoid receptors (MRs), producing aldosterone selectivity in vivo. At least two isoforms of 11β-HSD exist. One isoform (11β-HSD1) has been purified from rat liver and an encoding cDNA cloned from a rat liver library. Transfection of rat 11β-HSD1 cDNA into amphibian cells with a mineralocorticoid phenotype encodes 11 β-reductase activity (activation of inert 11-dehydrocorticosterone) suggesting that 11β-HSD1 does not have the necessary properties to protect renal MRs from exposure to glucocorticoids. This function is likely to reside in a second 11β-HSD isoform. 11β-HSD1 is co-localized with glucocorticoid receptors (GRs) and may modulate glucocorticoid access to this receptor type. To examine the predominant direction of 11β-HSD1 activity in intact mammalian cells, and the possible role of 11β-HSD in regulating glucocorticoid access to GRs, we transfected rat 11β-HSD1 cDNA into a mammalian kidney-derived cell system (COS-7) which has little endogenous 11β-HSD activity or mRNA expression. Homogenates of COS-7 cells transfected with increasing amounts of 11β-HSD cDNA exhibited a dose-related increase in 11 β-dehydrogenase activity. In contrast, intact cells did not convert corticosterone to 11-dehydrocorticosterone over 24 h, but showed a clear dose-related 11β-reductase activity, apparent within 4 h of addition of 11-dehydrocorticosterone to the medium. To demonstrate that this reflected a change in functional intracellular glucocorticoids, COS-7 cells were co-transfected with an expression vector encoding GR and a glucocorticoid-inducible MMTV-LTR luciferase reporter construct, with or without 11β-HSD. Corticosterone induced MMTV-LTR luciferase expression in the presence or absence of 11β-HSD. 11-Dehydrocorticosterone was without activity in the absence of 11β-HSD, but induced MMTV-LTR luciferase activity in the presence of 11β-HSD. These results indicate that rat 11β-HSD1 can behave exclusively as a reductase in intact mammalian cells. Thus in some tissues in vivo, 11β-HSD1 may regulate ligand access to GRs by reactivating inert glucocorticoids.

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