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Query: UMLS:C0338671 (Steroids)
 9,479 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Female rats, treated with allylisopropylacetamide (AIA) showed a marked decrease of hepatic NADH-5 alpha-reductase, NADPH-5 alpha-reductase, NAD+- and NADP+-3 alpha-hydroxysteroid dehydrogenase activities and an increase of the activity of NADH- and NADPH-5 beta-reductase and NAD+ and NADP+-3 beta-hydroxysteroid dehydrogenase. Administration of Sedormid decreased the activities of 5 alpha-reductases and 3 alpha-hydroxysteroid dehydrogenases (substrate, 5 alpha-dihydrotestosterone) and increased the activity of NADH-5 beta-reductase, whereas no effect was seen on NADPH-5 beta-reductase and 3 beta-hydroxysteroid dehydrogenase.
Steroids 1984 Sep
PMID:Effect of allylisopropylacetamide and Sedormid on enzymes of steroid metabolism in rat liver. 659 31

Testosterone biosynthesis by Leydig cells can be modulated by estradiol. This modulation appears to occur at the 17-hydroxylase and 17,20-desmolase stage. In this study we have examined the effects of estradiol and progesterone on the activities of the 17-hydroxylase (17-OH) and 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) in rat ovarian tissue, to examine the hypothesis that estradiol may regulate these enzymes in the ovary as well as in the testis. Estradiol capsule implants produced a decrease in 17-OH activity (0.5 +/- 0.05 vs. 2.1 +/- 0.1 nmol/mg protein/min, mean +/- SEM, p less than 0.001), and an increase in 3 beta-HSD activity (15.5 +/- 0.9 vs 9.7 +/- 0.7 nmol/mg protein/min p less than 0.001). Progesterone injections produced a decrease in both 17-OH (0.9 +/- 0.1 vs. 2.3 +/- 0.2 p less than 0.005) and 3 beta-HSD (2.5 +/- .4 vs. 8.6 +/- 0.5; p less than 0.005) activities. We conclude that estradiol decreases 17-OH activity in the ovary as it does in the testis. This, coupled with an increase in 3 beta-HSD may explain the pre-ovulatory increase in progesterone seen in many species. Progesterone seems to decrease the steroidogenic activity of the ovarian tissue, perhaps offering an explanation for the gonadotropin resistance seen in corpus luteus bearing ovaries.
Steroids 1983 Jan
PMID:The effects of estradiol and progesterone on rat ovarian 17-hydroxylase and 3 beta-hydroxysteroid dehydrogenase activities. 660 68

The influence of androgens on the FSH modulation of progestin biosynthetic enzymes was studied in vitro. Granulosa cells obtained from immature, hypophysectomized, estrogen-treated rats were cultured for 3 days in a serum-free medium containing FSH (20 ng/ml) with or without increasing concentrations (10(-9)-10(-6)M) or 17 beta-hydroxy-5 alpha-androstan-3-one (dihydrotestosterone; DHT), 5 alpha-androstane-3 alpha,17 beta-diol (3 alpha-diol), or the synthetic androgen 17 beta-hydroxy-17-methyl-4,9,11-estratrien-3-one (methyltrienolone; R1881). FSH treatment increased progesterone and 20 alpha-hydroxy-4-pregnen-3-one (20 alpha-OH-P) production by 10.2- and 11-fold, respectively. Concurrent androgen treatment augmented FSH-stimulated progesterone and 20 alpha-OH-P production in a dose-related manner (R1881 greater than 3 alpha-diol greater than DHT). In the presence of an inhibitor of 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD), the FSH-stimulated pregnenolone (3 beta-hydroxy-5-pregnen-20-one) production (a 20-fold increase) was further enhanced by co-treatment with R1881, 3 alpha-diol or DHT. Furthermore, FSH treatment increased 4.4-fold the activity of 3 beta-HSD, which converts pregnenolone to progesterone. This stimulatory action of FSH was further augmented by concurrent androgen treatment. In contrast, androgen treatment did not affect FSH-stimulated activity of a progesterone breakdown enzyme, 20 alpha-hydroxysteroid dehydrogenase (20 alpha-HSD). These results demonstrate that the augmenting effect of androgens upon FSH-stimulated progesterone biosynthesis is not due to changes in the conversion of progesterone to 20 alpha-OH-P, but involves an enhancing action upon 3 beta-HSD/delta 5,delta 4-isomerase complexes and additional enzymes prior to pregnenolone biosynthesis.
Steroids 1982 Dec
PMID:Androgen regulation of progestin biosynthetic enzymes in FSH-treated rat granulosa cells in vitro. 682 Dec 86

We have correlated the concentrations of serum LH, estradiol and progesterone with the activities of 2 ovarian steroid biosynthetic enzymes during the rat estrous cycle. Ovarian 3 beta-hydroxysteroid dehydrogenase isomerase (3-beta HSD) activity decreased from 29 +/- 6 nmol/mg protein/min (mean +/- SEM) in diestrus, to 7 +/- 0.4 nmol/mg protein/min in late proestrus (p less than 0.005), and subsequently increased to 36 +/- 9 nmol/mg protein/min in metestrus (p less than 0.01). Ovarian 17-hydroxylase (17-OH) activity decreased from early to late proestrus (3.3 +/- 0.2 vs 2.2 +/- 0.2 nmol/mg protein/min, p less than 0.0025), and subsequently increased to 3.9 +/- 0.2 in metestrus (p less than 0.001). Serum LH, estradiol and progesterone peaked during proestrus, and reached a nadir during estrus. We conclude that the activities of 3-beta HSD and 17-OH in the rat ovary vary markedly during the estrous cycle. These changes may underlie the pattern of steroid secretion characteristic of this process.
Steroids 1982 Aug
PMID:Ovarian steroidogenic enzyme activities during the rat estrous cycle. 689 9

5 alpha-Dihydrotestosterone, 17-hydroxyprogesterone caproate, 2-methoxyestrone and a number of nonsteroidal antiestrogens (clomiphene citrate, nafoxidine hydrochloride, tamoxifen, MER-25) were tested for their ability to block estradiol-mediated repression of the androgen-dependent 3 beta-hydroxysteroid dehydrogenase activity of male rat liver. With the exception of 5 alpha-dihydrotestosterone, which induced activity in females, none of these substances affected 3 beta-hydroxysteroid dehydrogenase activity when administered alone to otherwise untreated male and female rats. Tamoxifen (100 or 500 micrograms/day) was the only substance which prevented a decrease in enzyme activity when given simultaneously with estradiol (5 micrograms/day). The estradiol-mediated decrease in activity was not antagonized by a 100-fold higher dose of androgen (5 alpha-dihydrotestosterone, 0.5 mg/day), demonstrating the potent antiandrogenic effect of estradiol on this hepatic androgen-dependent enzyme activity.
Steroids 1980 Nov
PMID:Antagonism of the estradiol-mediated repression of microsomal 3 beta-hydroxysteroid dehydrogenase activity in rat liver by antiestrogenic substances. 693 24

A direct method for determination of delta 5 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) activity was employed in isolated Leydig cells (LC) derived from rats on fetal day 19 (Fig) and postnatal (N) days 1, 12, 24, 34 and 45 and adults. The activity of 3 beta-HSD in the adult LC was 1.15 +/- 0.02 (mumole/microgram DNA/hr, mean +/- SEM, n = 73). Activities in the other groups, expressed as a percentage of the respective adult control, were: Fig-38%; N1-39%; N12-8%; N24-89%; N34-166%; and N45-118%. A good correlation was found between histochemical staining for 3 beta-HSD and the quantitive method employed. Using (3H)-DHA as a substrate, LC isolated from F19, N1 and N12 produced testosterone in appreciable amounts (41%, 55% and 20% of the total products respectively) whereas at advanced stages of development (N24 to adulthood) the major product was androstenedione (93 +/- 1%). These findings may be explained by the observed decrease in 17 beta-hydroxysteroid dehydrogenase (17 beta-HSD) activity, due to an insufficient supply of NADPH, in the older vs. earlier stages of development. This study indicates the presence of steroidogenic enzymatic activity in LC throughout development in the rat. It also provides a relatively simple in vitro model for studies of testicular regulation during development.
Steroids 1980 Dec
PMID:Developmental pattern of delta 5 3 beta-hydroxysteroid dehydrogenase activity in isolated rat Leydig cells. 693 86

The synthesis, secretion and metabolism of progesterone have been examined in six human teratoma-derived cell lines with the objective of determining if they exhibit trophoblast-related or other specific steroidogenic functions. Progesterone was synthesised in nanogram amounts (per 10(6) cells/day) by the cell line SuSa, as measured by radioimmunoassay, and in lesser amounts by line LICR-LON HX-39. Lines Tera 1, Tera 2, T3B1 and PA-1 did not secrete detectable progesterone. All teratomas, however, metabolized added progesterone in microgram amounts (per 10(6) cells/day). In all cases the major metabolite was a polar compound, identified by reversed phase HPLC, TLC and GC-MS as 3 beta, 6 alpha-dihydroxy-5 alpha-pregnan-20-one. This pattern of metabolism was not confined to the teratomas as equivalent amounts of this polar metabolite were formed by cultures of adult differentiated human epithelial and fibroblast cells. When progesterone and its metabolites, separated by HPLC, were included in the estimation, the delta 5-3 beta-hydroxysteroid dehydrogenase-isomerase activity of SuSa was equivalent to 47ng pregnenolone (3 beta-hydroxy-5-pregnen-20-one) metabolised/mg protein/day, that of HX-39 to 9ng/ml protein/day and those of other teratomas to less than 3.5ng/mg protein/day.
Steroids 1981 Dec
PMID:Progesterone synthesis, secretion and metabolism by human teratoma-derived cell-lines. 695 May 73

The synthesis of 4-ethenylidene-5 alpha-androstane-3 beta, 17 beta-diol (5) and of 4-ethenylidene-5 alpha-androstane-3, 17-dione (4) is described. Compound 5 is a competitive inhibitor of solubilized bovine microsomal adrenal delta-5-3 beta-hydroxysteroid dehydrogenase, with Ki = 2.7 microM, and is converted by the enzyme to the corresponding 3-ketone. Compound 4 is shown to irreversibly inactivate the enzyme in a time-dependent manner (t 1/2 = 31 min; 55 microM; pH = 7.0). The substrate, dehydroepiandrosterone, protects against inactivation by compound 4. In contrast, compound 5 is not oxidized at the 3-position by the 3 beta-(and 17 beta)-hydroxysteroid dehydrogenase from P. testosteroni, but is oxidized at the 17-position. Nevertheless, the 4-ethenylidene-3,17-diketone (4) causes irreversible time-dependent inactivation (t 1/2 = 28 min; 64 microM; pH = 7.0) when incubated directly with this bacterial enzyme, acting as an affinity label.
Steroids 1982 Jul
PMID:4-Ethenylidene steroids as mechanism-based inactivators of 3 beta-hydroxysteroid dehydrogenases. 696 6

C17-20Lyase and 21-hydroxylase activities were measured during late gestation in the rhesus monkey (Macaca mulatta) fetal adrenal. Activities were assessed in 10,000 x g supernatants with 17-hydroxyprogesterone and NADPH as substrates. Although conversion of [14C]17-hydroxyprogesterone to [14C]androstenedione was noted, activity was often nonlinear and far less than the rate of hydroxylation which together prevented an accurate estimation of lyase rate, Km and Vmax. 21-Hydroxylase activity was characterized; the mean reaction rate was 1.6 x 10(-3) mumoles NADPH oxidized/min. x mg-1 protein with an apparent Km of 3.6 x 10(-7) M and a Vmax of 2.2 x 10(-3) mumoles/min. x mg-1 protein. These values were similar to data obtained in adrenals from adult monkeys. A relatively high level of hydroxylase activity in the fetal gland might lead to an inadequate supply of precursors for the synthesis of dehydroepiandrosterone sulfate (DHEAS) in the adrenal if it also contained 3 beta-hydroxysteroid dehydrogenase (3 beta-hsdh). However, the fact that the fetal adrenal reportedly is deficient in 3 beta-hsdh may serve to protect both DHEAS and corticoid synthesis.
Steroids 1981 Aug
PMID:17-Hydroxyprogesterone metabolism in the monkey fetal adrenal: C17-20lyase and 21-hydroxylase activities. 697 10

To characterize Leydig cell steroidogensis, we examined the metabolism of [3H]pregnenolone (3 beta-hydroxy-5-pregnen-20-one) to androgens in the presence and absence of human chorionic gonadotropin (hCG) as a function of culture duration. Approximately 20-30% of the (3H)pregnenolone was converted to testosterone (17 beta-hydroxy-4-androsten-3-one) by purified Leydig cells at 0, 3 and 5 days (d) of culture. Androstenedione (4-androstene-3,17-dione) and dihydrotestosterone (17 beta-hydroxy-5 alpha-androstan-3-one) were also produced while on day 5 of culture, significant amounts of progesterone (4-pregnene-3,20-dione) were isolated. The delta 5 intermediates, 17-hydroxypregnenolone (3 beta, 17-dihydroxy-5-pregnen-20-one) and dehydroepiandrosterone (3 beta-hydroxy-5-androsten-17-one), accounted for less than 1% of substrate conversion, indicating a clear preference for Leydig cells to metabolize (3H)pregnenolone via the delta 4 pathway. On day 0 of culture, unidentified metabolites considered of predominately polar steroids while on day 5 of culture, the unidentified metabolites consisted of predominately nonpolar steroids. In the presence of hCG, (3H-pregnenolone metabolism did not differ from basal on day 0 or 3 of culture. HCG increased the conversion of pregnenolone to progesterone and 17-hydroxyprogesterone (17-hydroxy-4-pregnene-3,20-dione) on 5d. This suggests that Leydig cells cultured for 5d have decreased C17-20 desmolase activity or that hCG acutely stimulates 3 beta-hydroxysteroid dehydrogenase and delta 5-delta 5 isomerase activities.
Steroids 1982 Nov
PMID:Steroid metabolism by purified adult rat Leydig cells in primary culture. 718 85


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