EFFECTS OF TAMOXIFEN ON THE BINDING AND METABOLISM OF TESTOSTERONE BY HUMAN PROSTATIC TISSUE AND PLASMA IN VITRO

1979 ◽  
Vol 83 (3) ◽  
pp. 369-378 ◽  
Author(s):  
F. K. HABIB ◽  
G. RAFATI ◽  
M. R. G. ROBINSON ◽  
S. R. STITCH
Keyword(s):  
Dehydrogenase Activity ◽  
Reductase Activity ◽  
Hydroxysteroid Dehydrogenase ◽  
Inhibitory Effect ◽  
Prostatic Tissue ◽  
Sex Hormone Binding Globulin ◽  
Benign Tissue ◽  
The Mean ◽  
Malignant Prostate

The in-vitro metabolism of testosterone in benign and malignant prostatic tissue was examined and distinct quantitative differences between the two types of specimens were observed. The major metabolite of testosterone in the hyperplastic prostate was 5α-dihydrotestosterone and a high 3α(β)-hydroxysteroid dehydrogenase activity was also detected. In the malignant tissue, 5α-reductase activity was considerably reduced and there was little or no androstanediol formed; the 17β-dehydrogenase activity was, however, higher than in the benign tissue. The decrease in 5α-reductase was always followed by a compensatory change in the 3α(β)-hydroxysteroid dehydrogenase of the malignant prostate. The present study revealed that the ratio of the mean activities of 5α-reductase to 3α(β)-hydroxysteroid dehydrogenase in the two types of specimen always remained a constant. Although the antioestrogen, tamoxifen, induced an inhibitory effect on the activities of 5α-reductase and 17β-hydroxysteroid dehydrogenase in the gland, the present investigation also suggested that tamoxifen stimulated the activity of 3α(3β)-hydroxysteroid dehydrogenase. In blood, the action of tamoxifen appeared to be confined to the displacement of androgens from the binding sites on the sex hormone binding globulin.

INCREASED RATIO OF 5α-REDUCTASE: 3α(β)-HYDROXYSTEROID DEHYDROGENASE ACTIVITIES IN THE HYPERPLASTIC HUMAN PROSTATE

1979 ◽  
Vol 80 (3) ◽  
pp. 289-301 ◽  
Author(s):  
NICHOLAS BRUCHOVSKY ◽  
GARY LIESKOVSKY
Keyword(s):  
Enzyme Activity ◽  
Dehydrogenase Activity ◽  
Reductase Activity ◽  
Hydroxysteroid Dehydrogenase ◽  
Normal Prostate ◽  
Tissue Protein ◽  
Abnormal Accumulation ◽  
Hyperplastic Tissue ◽  
The Mean ◽  
Generating System

The activities of 5α-reductase and 3α(β)-hydroxysteroid dehydrogenase were assayed in homogenates of eight normal, 21 hyperplastic and four carcinomatous human prostates. Samples consisting of 300–500 μg tissue protein in Tris buffer, pH 7·0, were incubated at 37 °C for 30 min in the presence of 50 nm-[3H]androgen and an NADPH-generating system started with 5 × 10−4 m-NADP. The yield of 5α- and 3α-reduced metabolites, as established by using t.l.c. and g.l.c., gave an estimate of enzyme activity. The formation of metabolites denoting 5α-reductase activity in normal, hyperplastic and carcinomatous tissue respectively was 28·8 ± 47 (s.e.m.), 76·8 ± 8·9 and 3·5 ± 0·7 pmol 30 min−1 mg protein−1; similarly, that denoting 3α(β)-hydroxysteroid dehydrogenase activity was 69·3 ± 6·7, 46·6 ± 5·7 and 38·8 ± 22·1 pmol 30 min−1 mg protein−1. In all normal prostates 5α-reductase activity was lower than 3α(β)-hydroxysteroid dehydrogenase activity. Conversely, in 18 out of 21 hyperplastic prostates, 5α-reductase activity was higher than 3α(β)-hydroxysteroid dehydrogenase activity. The effect of the increase in 5α-reductase activity without a compensatory change in 3α(β)-hydroxysteroid dehydrogenase activity was to alter the mean ratio between 5α-reductase and 3α(β)-hydroxysteroid dehydrogenase activities from 0·47 ± 0·11 in the normal prostate to 1·84 ± 0·19 in hyperplastic tissue. It is inferred that this change may predispose the hyperplastic prostate to asymmetrical rates of androgen metabolism and thereby contribute to the abnormal accumulation of dihydrotestosterone.

'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.

HYPOTHALAMIC, PITUITARY AND TESTICULAR FUNCTION DURING SEXUAL MATURATION OF THE MALE RAT

1977 ◽  
Vol 72 (1) ◽  
pp. 17-26 ◽  
Author(s):  
A. H. PAYNE ◽  
R. P. KELCH ◽  
E. P. MURONO ◽  
J. T. KERLAN
Keyword(s):  
Dehydrogenase Activity ◽  
Sexual Maturation ◽  
Hydroxysteroid Dehydrogenase ◽  
Male Rat ◽  
Releasing Hormone ◽  
Isomerase Activity ◽  
Serum Lh ◽  
Rate Of Increase ◽  
Gonadotrophin Releasing Hormone

SUMMARY Hypothalamic content of gonadotrophin-releasing hormone (GnRH), serum LH and FSH, capacity of the testis to synthesize testosterone in vitro, and testicular 5-ene-3β-hydroxysteroid dehydrogenase-isomerase and 17β-hydroxysteroid dehydrogenase were measured in groups of rats at approximately 5 day intervals from birth to day 64 and at days 74 and 89. The capacity of the testes to synthesize testosterone in vitro was measured in the presence of a saturating dose of rat LH. Gonadotrophin-releasing hormone increased steadily from 0·17 ng per hypothalamus at birth to a maximum of 7 ng at day 52 and then remained constant. LH concentrations were highly variable and often exceeded adult values between days 10 and 32. After day 32 a steady rise was observed which reached adult values between days 37 and 42. FSH concentrations markedly increased from 255 ng/ml observed at birth and day 10 to a peak value of 1000 ng/ml at day 32. Subsequently there was a steady decline in FSH values until day 74 when the concentration returned to values found at birth. 5-ene-3β-Hydroxysteroid dehydrogenase-isomerase activity exhibited a rapid increase between days 12 and 19 followed by an even greater rate of increase between days 19 and 32 when adult levels were attained. 17β-Hydroxysteroid dehydrogenase activity was very low between birth and day 22. Enzyme activity began to increase at day 22 with a rapid increase in activity observed between days 37 and 58. The increase in capacity to synthesize testosterone closely followed the increase in 17β-hydroxysteroid dehydrogenase activity. The study demonstrates that during sexual maturation in the male rat, changes in serum LH and FSH do not reflect changes in hypothalamic GnRH. The appearance of Leydig cells as monitored by 5-ene-3β-hydroxysteroid dehydrogenase-isomerase activity precedes by approximately 20 days the increase in testicular capacity to synthesize testosterone in vitro. The latter coincides with the increase in 17β-hydroxysteroid dehydrogenase activity. These results suggest that 17β-hydroxysteroid dehydrogenase is a limiting factor in the ability of the testis to respond to LH stimulation.

Intracellular regulation of 17β-hydroxysteroid dehydrogenase type 2 catalytic activity in A431 cells

1997 ◽  
Vol 153 (3) ◽  
pp. 453-464 ◽  
Author(s):  
C H Blomquist ◽  
B S Leung ◽  
C Beaudoin ◽  
D Poirier ◽  
Y Tremblay
Keyword(s):  
Reductase Activity ◽  
Maximum Velocity ◽  
Hydroxysteroid Dehydrogenase ◽  
A431 Cells ◽  
Intact Cells ◽  
Cell Monolayers ◽  
Intracellular Regulation

Abstract There is growing evidence that various isoforms of 17β-hydroxysteroid dehydrogenase (17-HSD) are regulated at the level of catalysis in intact cells. A number of investigators have proposed that the NAD(P)/NAD(P)H ratio may control the direction of reaction. In a previous study, we obtained evidence that A431 cells, derived from an epidermoid carcinoma of the vulva, are enriched in 17-HSD type 2, a membrane-bound isoform reactive with C18 and C19 17β-hydroxysteroids and 17-ketosteroids. The present investigation was undertaken to confirm the presence of 17-HSD type 2 in A431 cells and to assess intracellular regulation of 17-HSD at the level of catalysis by comparing the activity of homogenates and microsomes with that of cell monolayers. Northern blot analysis confirmed the presence of 17-HSD type 2 mRNA. Exposure of cells to epidermal growth factor resulted in an increase in type 2 mRNA and, for microsomes, increases in maximum velocity (Vmax) with no change in Michaelis constant (Km) for testosterone and androstenedione, resulting in equivalent increases in the Vmax/Km ratio consistent with the presence of a single enzyme. Initial velocity data and inhibition patterns were consistent with a highly ordered reaction sequence in vitro in which testosterone and androstenedione bind only to either an enzyme–NAD or an enzyme–NADH complex respectively. Microsomal dehydrogenase activity with testosterone was 2- to 3-fold higher than reductase activity with androstenedione. In contrast, although cell monolayers rapidly converted testosterone to androstenedione, reductase activity with androstenedione or dehydroepiandrosterone (DHEA) was barely detectable. Lactate but not glucose, pyruvate or isocitrate stimulated the conversion of androstenedione to testosterone by monolayers, suggesting that cytoplasmic NADH may be the cofactor for 17-HSD type 2 reductase activity with androstenedione. However, exposure to lactate did not result in a significant change in the NAD/NADH ratio of cell monolayers. It appears that within A431 cells 17-HSD type 2 is regulated at the level of catalysis to function almost exclusively as a dehydrogenase. These findings give further support to the concept that 17-HSD type 2 functions in vivo principally as a dehydrogenase and that its role as a reductase in testosterone formation by either the Δ4 or Δ5 pathway is limited. Journal of Endocrinology (1997) 153, 453–464

EFFECTS OF HYDROXYSTEROID DEHYDROGENASE INHIBITORS ON IN-VITRO AND IN-VIVO STEROIDOGENESIS IN THE OVINE ADRENAL GLAND

1982 ◽  
Vol 92 (2) ◽  
pp. 205-212 ◽  
Author(s):  
P. SINGH-ASA ◽  
G. JENKIN ◽  
G. D. THORBURN
Keyword(s):  
Adrenal Gland ◽  
Incubation Medium ◽  
Bovine Serum ◽  
Hydroxysteroid Dehydrogenase ◽  
Inhibitory Effect ◽  
Bovine Serum Albu ◽  
Stimulatory Action ◽  
Adrenal Steroidogenesis

The effectiveness of trilostane and azastene as inhibitors of adrenal steroidogenesis was compared by in-vitro and in-vivo methods. A radioimmunoassay was developed for the measurement of cortisol in ovine plasma, incubation medium and tissue extract using a specific antiserum raised against cortisol 21-acetate,3-carboxymethyloxime : bovine serum albu Trilostane (20 μmol/l) decreased cortisol synthesis and release both in unstimulated and in ACTH-stimulated adrenal tissues in vitro. The same concentration of azastene had a lesser effect on unstimulated adrenals and was completely ineffective in blocking the stimulatory action of ACTH. In vivo, trilostane suppressed adrenal steroidogenesis in pregnant and cyclic ewes but the suppression in pregnant ewes was over a longer period, and after lower doses. It is concluded that trilostane had an inhibitory effect on ovine adrenal steroidogenesis both in vitro and in vivo.

scholarly journals Modulation of 11β-Hydroxysteroid Dehydrogenase Isozymes by Growth Hormone and Insulin-Like Growth Factor: In Vivo and In Vitro Studies1

1999 ◽  
Vol 84 (11) ◽  
pp. 4172-4177 ◽  
Author(s):  
J. S. Moore ◽  
J. P. Monson ◽  
G. Kaltsas ◽  
P. Putignano ◽  
P. J. Wood ◽  
...  
Keyword(s):  
Growth Factor ◽  
Reductase Activity ◽  
Primary Cultures ◽  
Inverse Correlation ◽  
Hydroxysteroid Dehydrogenase ◽  
Insulin Like Growth Factor ◽  
Igf I ◽  
Glucose Output

The interconversion of hormonally active cortisol (F) and inactive cortisone (E) is catalyzed by two isozymes of 11β-hydroxysteroid dehydrogenase (11βHSD), an oxo-reductase converting E to F (11βHSD1) and a dehydrogenase (11βHSD2) converting F to E. 11βHSD1 is important in mediating glucocorticoid-regulated glucose homeostasis and regional adipocyte differentiation. Earlier studies conducted with GH-deficient subjects treated with replacement GH suggested that GH may modulate 11βHSD1 activity. In 7 acromegalic subjects withdrawing from medical therapy (Sandostatin-LAR; 20–40 mg/month for at least 12 months), GH rose from 7.1 ± 1.5 to 17.5 ± 4.3 mU/L (mean ± se), and insulin-like growth factor I (IGF-I) rose from 43.0 ± 8.8 to 82.1 ± 13.7 nmol/L (both P < 0.05) 4 months after treatment. There was a significant alteration in the normal set-point of F to E interconversion toward E. The fall in the urinary tetrahydrocortisols/tetrahydocortisone ratio (THF+allo-THF/THE; 0.82 ± 0.06 to 0.60 ± 0.06; P < 0.02) but unaltered urinary free F/urinary free E ratio (a marker for 11βHSD2 activity) suggested that this was due to inhibition of 11βHSD1 activity. An inverse correlation between GH and the THF+allo-THF/THE ratio was observed (r = −0.422; P < 0.05). Conversely, in 12 acromegalic patients treated by transsphenoidal surgery (GH falling from 124 ± 49.2 to 29.3 ± 15.4 mU/L; P < 0.01), the THF+allo-THF/THE ratio rose from 0.53 ± 0.06 to 0.63 ± 0.07 (P < 0.05). Patients from either group who failed to demonstrate a change in GH levels showed no change in the THF+allo-THF/THE ratio. In vitro studies conducted on cells stably transfected with either the human 11βHSD1 or 11βHSD2 complementary DNA and primary cultures of human omental adipose stromal cells expressing only the 11βHSD1 isozyme indicated a dose-dependent inhibition of 11βHSD1 oxo-reductase activity with IGF-I, but not GH. Neither IGF-I nor GH had any effect on 11βHSD2 activity. GH, through an IGF-I-mediated effect, inhibits 11βHSD1 activity. This reduction in E to F conversion will increase the MCR of F, and care should be taken to monitor the adequacy of function of the hypothalamo-pituitary-adrenal axis in acromegalic subjects and in GH-deficient, hypopituitary patients commencing replacement GH therapy. Conversely, enhanced E to F conversion occurs with a reduction in GH levels; in liver and adipose tissue this would result in increased hepatic glucose output and visceral adiposity, suggesting that part of the phenotype currently attributable to adult GH deficiency may be an indirect consequence of its effect on tissue F metabolism via 11βHSD1 expression.

scholarly journals Leptomeningeal Cells Transduce Peripheral Macrophages Inflammatory Signal to Microglia in Reponse toPorphyromonas gingivalisLPS

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Yicong Liu ◽  
Zhou Wu ◽  
Xinwen Zhang ◽  
Junjun Ni ◽  
Weixian Yu ◽  
...  
Keyword(s):  
Conditioned Medium ◽  
Chronic Periodontitis ◽  
Human Monocyte ◽  
Inhibitory Effect ◽  
Mrna Levels ◽  
Proinflammatory Mediators ◽  
Raw264.7 Macrophages ◽  
Inflammatory Signals ◽  
The Mean

We report here that the leptomeningeal cells transduce inflammatory signals from peripheral macrophages to brain-resident microglia in response toPorphyromonas gingivalis (P.g.)LPS. The expression of Toll-like receptor 2 (TLR2), TLR4, TNF-α, and inducible NO synthase was mainly detected in the gingival macrophages of chronic periodontitis patients. Inin vitrostudies,P.g.LPS induced the secretion of TNF-αand IL-1βfrom THP-1 human monocyte-like cell line and RAW264.7 mouse macrophages. Surprisingly, the mean mRNA levels of TNF-αand IL-1βin leptomeningeal cells after treatment with the conditioned medium fromP.g.LPS-stimulated RAW264.7 macrophages were significantly higher than those after treatment withP.g.LPS alone. Furthermore, the mean mRNA levels of TNF-αand IL-1βin microglia after treatment with the conditioned medium fromP.g.LPS-stimulated leptomeningeal cells were significantly higher than those afterP.g.LPS alone. These observations suggest that leptomeninges serve as an important route for transducing inflammatory signals from macrophages to microglia by secretion of proinflammatory mediators during chronic periodontitis. Moreover, propolis significantly reduced theP.g.LPS-induced TNF-αand IL-1βproduction by leptomeningeal cells through inhibiting the nuclear factor-κB signaling pathway. Together with the inhibitory effect on microglial activation, propolis may be beneficial in preventing neuroinflammation during chronic periodontitis.

Effect of Ethanol on Erythrocyte Acetylcholinesterase Activity

1986 ◽  
Vol 23 (4) ◽  
pp. 458-462 ◽  
Author(s):  
Nuha A Haboubi ◽  
D I Thurnham
Keyword(s):  
Ache Activity ◽  
Acetylcholinesterase Activity ◽  
Inhibitory Effect ◽  
In Vitro Experiments ◽  
Previous Exposure ◽  
Organophosphorus Poisoning ◽  
The Mean ◽  
Erythrocyte Ache ◽  
Early Indication

Erythrocyte acetylcholinesterase (AchE) activity was measured in the blood of 36 alcoholic subjects and 41 healthy volunteers. The mean activity in the alcoholics was significantly lower than that in the control subjects. In vitro experiments showed that ethanol inhibited the AchE activity immediately and in proportion to the concentration of ethanol used. Incubation times up to 6 h did not increase the inhibition significantly. Incubation of normal red cells with ethanol for 15 h, followed by washing, showed also that AchE activity was inhibited by the previous exposure to ethanol and that washing did not reduce the inhibitory effect. The possibility is considered that depressed erythrocyte AchE activity may be an early indication of potential disturbances of the autonomic nervous system. The importance of reporting ethanol intake in patients with organophosphorus poisoning is stressed.

17β-HYDROXYSTEROID DEHYDROGENASE ACTIVITY IN HUMAN TESTES

1967 ◽  
Vol 56 (1) ◽  
pp. 56-64 ◽  
Author(s):  
Edgar J. Schoen
Keyword(s):  
Dehydrogenase Activity ◽  
Conversion Rate ◽  
Prostatic Carcinoma ◽  
Hydroxysteroid Dehydrogenase ◽  
Testicular Tissue

ABSTRACT In vitro 17β-hydroxysteroid dehydrogenase activity in testicular tissue from 7 men subjected to orchiectomy for prostatic carcinoma was measured by the conversion rate of androstenedione to testosterone. Prior to orchiectomy, 3 of the patients were untreated: 3 had received stilboestrol. 5 mg daily for one month; 1 had received stilboestrol, 2 mg daily for one month. There was evidence that stilboestrol in a dosage of 5 mg daily for one month prior to orchiectomy led to suppression of testosterone formation from androstenedione. 17β-Hydroxysteroid dehydrogenase activity could be demonstrated in small quantities of testicular homogenate, and thus offers an additional technique for assessing testicular androgenic function in man.

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