METABOLISM OF [14C]TESTOSTERONE BY HUMAN FOETAL AND ADULT BRAIN TISSUE

1977 ◽  
Vol 74 (3) ◽  
pp. 425-429 ◽  
Author(s):  
J. S. JENKINS ◽  
C. J. HALL
Keyword(s):  
Pituitary Gland ◽  
Brain Tissue ◽  
Temporal Lobe ◽  
Reductase Activity ◽  
Hydroxysteroid Dehydrogenase ◽  
Adult Brain ◽  
Similar Activity ◽  
Foetal Brain ◽  
Brain Tissues

SUMMARY The metabolism of [14C]testosterone in vitro by various areas of the human foetal brain has been studied and compared with that of adult brain. The predominant metabolites were 5α-dihydrotestosterone and 5α-androstane-3α,17β-diol, and also androstenedione, and all areas of the foetal brain showed similar activity. In the foetal pituitary gland, the activity of 5α-reductase was less prominent than that of 17β-hydroxysteroid-dehydrogenase. Small quantities of oestradiol-17β were produced from testosterone by the hypothalamus, temporal lobe and amygdala only, and no aromatization could be detected in the pituitary gland. 5α-Reductase activity was much lower in adult brain tissues and no oestradiol was identified in adult temporal lobe tissue.

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

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.

Radiation induced chromosome aberrations in human foetal cells grown in vitro

1962 ◽  
Vol 11 (4) ◽  
pp. 356-389 ◽  
Author(s):  
J. A. Böök ◽  
M. Fraccaro ◽  
K. Fredga ◽  
J. Lindsten
Keyword(s):  
Brain Tissue ◽  
Cell Cultures ◽  
Lung Tissue ◽  
Cultured Cells ◽  
Absorbed Dose ◽  
Cell Populations ◽  
Foetal Brain ◽  
Radiation Induced ◽  
Foetal Lung

SUMMARYThe effect of ionizing radiation, from a 100 Curie Cobalt-60 source, on diploid human cells grown in vitro has been investigated.The analysed cell populations originated from foetal brain and lung tissue. Other known variations of this material were age and sex of the foetuses, primary and first transfer cultures.The effect was measured by recording post-metaphase chromosomal aberrations in cell cultures fixed and stained 24 and 48 hours after acute irradiation. “Spontaneous” aberration frequencies were determined in matched control cultures.Although conclusions must be guarded, in view of the insufficient knowledge of factors influencing human cell populations in vitro, our observations can be summarized, tentatively, in the following main points.1. The frequency of “spontaneous” aberrations appears to vary with respect to (a) differences between the individuals from whom the biopsies were taken, (b) tissue of origin whether within or between individuals and (c) the sex of the cultured cells.The qualified estimates of the overall averages of “spontaneous” aberrations were, (a) for the cell cultures derived from foetal lung 0.7 per cent (41/5,891 scored cells) and (b) for the cell cultures derived from foetal brain 2.5 per cent (21/851 scored cells).2. In the irradiated cell cultures which received doses varying from 9-136 rads of absorbed dose the number of aberrant post-metaphases per 100 cells per rad varied from 0.10-0.15 for cultures derived from lung tissue and from 0.19-0.37 for cultures derived from brain tissue, all at 24 hours after the acute dose. At 48 hours after irradiation the frequencies were somewhat lower but the same trends remained.3. The cell cultures derived from brain tissue appear to have a higher radio-sensitivity than those derived from lung tissue. Furthermore, a sexual dimorphism is suggested because, in all series of cultures, those composed of XY cells had a higher aberration frequency as compared to those with XX cells.4. The irradiation doubling dose (for definition, see p. 27) was estimated at 15-40 rads (cf. table 7).

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.

Adaptation of adult brain tissue to anoxia and hypoxia in vitro

1986 ◽  
Vol 374 (2) ◽  
pp. 244-248 ◽  
Author(s):  
Avital Schurr ◽  
Kenneth H. Reid ◽  
Michael T. Tseng ◽  
Catherine West ◽  
Benjamin M. Rigor
Keyword(s):  
Brain Tissue ◽  
Adult Brain

scholarly journals Functional maturation of human neural stem cells in a 3D bioengineered brain model enriched with fetal brain-derived matrix

2019 ◽  
Author(s):  
Disha Sood ◽  
Dana M. Cairns ◽  
Jayanth M. Dabbi ◽  
Charu Ramakrishnan ◽  
Karl Deisseroth ◽  
...  
Keyword(s):  
Stem Cells ◽  
Neural Stem Cells ◽  
Brain Tissue ◽  
Fetal Brain ◽  
Functional Differentiation ◽  
Adult Brain ◽  
Human Neural Stem Cells ◽  
Functional Maturation ◽  
Enriched Cultures

AbstractBrain extracellular matrix (ECM) is often overlooked in vitro brain tissue models, despite its instructive roles during development. Using developmental stage-sourced brain ECM in reproducible 3D bioengineered culture systems, we demonstrate enhanced functional differentiation of human induced neural stem cells (hiNSCs) into healthy neurons and astrocytes. Particularly, fetal brain tissue-derived ECM supported long-term maintenance of differentiated neurons, demonstrated by morphology, gene expression and secretome profiling. Astrocytes were evident within the second month of differentiation, and reactive astrogliosis was inhibited in brain ECM-enriched cultures when compared to unsupplemented cultures. Functional maturation of the differentiated hiNSCs within fetal ECM-enriched cultures was confirmed by calcium signaling and unsupervised cluster analysis. Additionally, the study identified native biochemical cues in decellularized ECM with notable comparisons between fetal and adult brain-derived ECMs. The development of novel brain-specific biomaterials for generating mature in vitro brain models provides an important path forward for interrogation of neuron-glia interactions.

ANDROGEN DEPENDENCE OF RAT PROSTATIC 3α-HYDROXYSTEROID DEHYDROGENASE

1978 ◽  
Vol 79 (1) ◽  
pp. 143-144 ◽  
Author(s):  
R. MASSA ◽  
M. MAS GARCIA ◽  
L. MARTINI
Keyword(s):  
Anterior Pituitary ◽  
Reductase Activity ◽  
Prostate Gland ◽  
Hydroxysteroid Dehydrogenase ◽  
Irreversible Reaction ◽  
Dehydrogenase System ◽  
Rat Prostate ◽  
Biological Actions

Department of Endocrinology, University of Milan, Via A. del Sarto 21, 20129 Milan, Italy (Received 8 May 1978) It is well established that the rat prostate gland converts testosterone mainly into 5α-androstan-17β-ol-3-one (5α-dihydrotestosterone, 5α-DHT) and to a lesser extent into 5α-androstan-3α,17β-diol (5α-tetrahydrotestosterone, 5α-THT). This occurs, both in vivo and in vitro, through the action of a 5α-reductase and a 3α-hydroxysteroid dehydrogenase system (Baulieu, Lasnitzki & Robel, 1968; Bruchovsky & Wilson, 1968; Gloyna & Wilson, 1969; Kniewald, Massa & Martini, 1971). It has also been recognized that, although the 5α-reduction of testosterone is an irreversible reaction, the reduction of 5α-DHT to 5α-THT is reversible (Becker, Grabosch, Hoffmann & Voigt, 1973; Cresti & Massa, 1977). Consequently, the question has been raised as to whether the biological actions of 5α-THT are attributable to the compound as such or to 5α-DHT. At the anterior pituitary level, 5α-reductase activity is increased by castration and decreased

Metabolism and receptor binding of nandrolone and testosterone under in vitro and in vivo conditions

1985 ◽  
Vol 110 (3_Suppla) ◽  
pp. S31-S37 ◽  
Author(s):  
E. W. Bergink ◽  
J. A. A. Geelen ◽  
E. W. Turpijn
Keyword(s):  
Androgen Receptor ◽  
Receptor Binding ◽  
Reductase Activity ◽  
Hydroxysteroid Dehydrogenase ◽  
In Vivo Studies ◽  
Muscular Tissue ◽  
Binding Studies ◽  
Tissue Homogenates

Abstract. The metabolism and receptor binding of nandrolone (N) and testosterone (T) were studied under in vitro and in vivo conditions. The results of both in vitro incubation studes with 3H-N and 3H-T in tissue homogenates from rats and in vivo infusion studies with 3H-N and 3H-T in conscious rats show the importance of the enzymes 5α-reductase and 3α/β-hydroxysteroid-oxidoreductases in the prostate and the importance of the enzyme 17β-hydroxysteroid dehydrogenase in the kidney for the effects of N and T on these tissues. Following infusion of a combined dose of 3H-N and 3H-T there is a preferential retention at the receptor of 5α-dihydrotestosterone (DHT) over 5α-dihydronandrolone (DHN), N and T (DHT ⪢ DHN > N > T) in the prostate because T is a better substrate than N for 5α-reductase and because DHT binds more strongly to the androgen receptor than DHN, N and T. In the kidney 5α-reductase is not important; there is a preferential retention of N in T (DHN and DHT were only present in small amounts) because N is less susceptible than T for metabolic inactivation by the enzyme 17β-hydroxysteroid dehydrogenase and N binds strongly to the androgen receptor. Both in vitro and in vivo studies show that N and T were relatively stable in spleen, thymus and muscular tissue (only shown in vivo) and, as a result, the same amount of N and T was bound to the receptor in these tissues in the in vivo infusion experiment. In vitro binding studies with the androgen receptor in intact human cells show that 5α-reduction increases the affinity of T and decreases the affinity of N and of the 17α-ethyl derivative of N (3-keto-ethylestrenol). The results of the present studies explain the relatively strong effect of N, or derivatives of N, compared to that of T on tissues devoid of 5α-reductase activity (e.g. muscular tissue) and they suggest that in particular there may be a strong effect of N on tissues which in addition have a high 17β-hydroxysteroid dehydrogenase activity (e.g. kidney).

Androgen 5α-reductase and 3α-hydroxysteroid dehydrogenase activities in ventral prostate epithelial and stromal cells from immature and mature rats

1983 ◽  
Vol 99 (1) ◽  
pp. 131-139 ◽  
Author(s):  
J. Orlowski ◽  
C. E. Bird ◽  
A. F. Clark
Keyword(s):  
Epithelial Cells ◽  
Stromal Cells ◽  
Reductase Activity ◽  
Age Groups ◽  
Cell Types ◽  
Hydroxysteroid Dehydrogenase ◽  
Ventral Prostate ◽  
Testosterone Metabolism ◽  
Immature Rats

To study androgen-mediated differentiation in the rat ventral prostate, we separated the two principal cell types (epithelial and stromal) derived from prostates of immature and mature rats on two continuous Percoll gradients. Cells were immediately placed in culture medium. Testosterone metabolism by the two prostatic cell types was evaluated using [3H]testosterone and quantifying the formation of 5α-[3H]dihydrotestosterone (5α-DHT) and 5α-[3H]androstane-(3α or 3β), 17β-diols. In epithelial cells from both immature and mature rat prostates the major testosterone metabolites were 5α-DHT and 5α-androstane-3α, 17β-diol. Stromal cells metabolized less testosterone than did the epithelial cells. Differences in the relative levels of the various metabolites were observed for the two age groups. To examine in more detail the changes in testosterone metabolism observed in vitro both types of cells and unfractionated cells from immature and mature rat prostates were assayed for testosterone 5α-reductase (using testosterone as substrate) and 3α-hydroxysteroid dehydrogenase (using 5α-DHT as substrate) activities (expressed as pmol substrate reduced/min per 106 cells). In immature rats both 5α-reductase and 3α-hydroxysteroid dehydrogenase activities were localized in the epithelial cell fraction (17 and 52 respectively); stromal cells showed lower 5α-reductase and 3α-hydroxysteroid dehydrogenase activity (4 and 4). Relative to epithelial cells from immature rats epithelial cells from mature rats showed a decrease in 5α-reductase (7) and an increase in 3α-hydroxysteroid dehydrogenase (160) activity while stromal 5α-reductase showed little change (3) and 3α-hydroxysteroid dehydrogenase increased to 22. Because there are more epithelial than stromal cells in the rat prostate, the former can be considered important sites for 5α-reductase and 3α-hydroxysteroid dehydrogenase activities. This contrasts with the human prostate where there is more 5α-reductase activity in the stroma than in the epithelium.

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