Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0338671 (Steroids)
 9,479 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Inhibition of 5 alpha-reductase and anti-androgenicity were studied in rats treated with various 4-azasteroids. The known inhibitor, N,N-diethyl-4-methyl-3-oxo-4-aza-5 alpha-androstane-17 beta-carboxamide (4-MA) served as a reference compound, and analogs of this basic molecule were assayed. Enhancement of enzyme inhibitory potency was usually seen with delta 1 analogs, whereas reduction in activity was noted with substitutuents such as delta 5, a spirotetrahydrofuran ring at C-17 or 4-deaza groups. Many of the 4-azasteroids had a much greater oral anti-androgenic effect against testosterone propionate (TP) than dihydrotestosterone propionate (DHTP). This difference in activity versus the two androgens is believed to reflect the necessity for TP to undergo reduction to DHT before becoming capable of stimulating prostatic growth. Inhibition of 5 alpha-reductase by active compounds prevented the conversion, thereby producing an anti-androgenic effect. In this regard, certain delta 1 analogs of 4-MA, particularly those bearing a 17 beta-(N-tert butylcarbamoyl) group, proved very effective against TP but were relatively inactive versus DHTP.
Steroids 1986 Jan
PMID:5 Alpha-reductase inhibitory and anti-androgenic activities of some 4-azasteroids in the rat. 381 Jun 95

In cell-free systems androgen receptor (AR) labeled with (3H)DHT at 0 degrees C in the presence of 50mM molybdate remains unactivated (less than 3% binding to nuclei) and untransformed (7-8S on sucrose density gradients containing 0.4M KCl and 50mM molybdate). In the absence of molybdate, however, these complexes undergo activation and transformation even at 0 degrees C, albeit, very slowly. Incubation of unactivated, untransformed AR complexes at 18 degrees C, or at 0 degrees C in the presence of 0.4M KCl, greatly accelerated both activation and transformation. Activation and transformation are also associated with formation of high affinity (3H)DHT-receptor complexes as indicated by decreased rates of (3H)DHT dissociation from the receptor. Cytosolic AR complexes labeled with (3H)DHT in tissue slices at 37 degrees C, or in vivo, undergo rapid activation, transformation and nuclear translocation. The data suggest that activation and transformation of cytosolic AR in cell-free systems is associated with changes in the physicochemical properties of AR similar to those occurring upon hormone binding in intact cells and in vivo.
Steroids 1985 Dec
PMID:Changes in the sedimentation properties of cytosolic androgen receptors associated with activation in vitro and in vivo. 384 22

A simplified, rapid, and highly reproducible technique is described for measuring 5 alpha-reductase activity (5 alpha RA) in small skin biopsies. Human genital skin was obtained from 23 nonhirsute and 20 hirsute premenopausal women (HW) and 5 normal men. Skin samples were minced at 4 C and incubated with RPMI-1640 in the presence of 95% O2-5% CO2 and 4.15 nmol [14C]testosterone ([14C]T) for 2 h at 37 C. Steroids were extracted with diethyl ether and separated by Celite and paper chromatography. Radioactivity in specific eluates was quantified, and the mass of each steroid was measured by RIA. The separate formation of 5 alpha-androstane-17 beta-ol-3-one (DHT), 5 alpha-androstane-3 alpha, 17B diol (3 alpha diol), androstenedione, and androsterone from [14C]T was measured. In separate experiments it was demonstrated that an incubation time of 2 h was optimum and that the addition of cofactors was unnecessary. Radiochemical purity was confirmed after chromatography. The mean +/- SE conversion ratio (CR) of T to DHT (in 2 h) in HW was higher than that in normal women (16.80 +/- 1.62% vs. 4.48 +/- 0.36%; P less than 0.01). In men, the CR of T to DHT averaged 31.60 +/- 3.96%. Individual values for the CR of T to DHT in HW and normal women did not overlap. The CR of T to 3 alpha diol was significantly higher in HW (9.66 +/- 0.86%) and men (15.98 +/- 2.0%) compared to that in normal women (2.96 +/- 0.32%; P less than 0.05). The CR of T to androstenedione was significantly greater in HW and men (6.18 +/- 0.42 and 7.28 +/- 1.92%) compared to that in normal women (2.64 +/- 0.64%; P less than 0.05). The CR of T to androsterone was very low and was similar in the three groups. The production of DHT in HW (4.50 +/- 1.0 pmol/mg X 2 h) was significantly greater than that in normal women (0.48 +/- 0.08; P less than 0.01) and was similar to the production in men (6.18 +/- 1.94 pmol/mg X 2 h). There was a significant correlation between the CR of T to DHT and DHT production, and the CR of T to 3 alpha diol and 3 alpha diol production as well as between the CRs of T to DHT and T to 3 alpha diol. These data suggest that measurements of DHT formation are best suited for the assessment of 5 alpha RA and that the measurement of 5 alpha RA in vitro from small skin biopsies is suitable for the clinical evaluation of hirsutism.
 ...
PMID:5 alpha-Reductase activity in the genital skin of hirsute women. 396 94

We examined the influences of steroids present in the epididymis on androgen metabolism by epididymal tissue and on the binding of androgen metabolites to the epididymal androgen receptor in castrated adult rabbit epididymides under in vitro conditions. The conversion of [3H]testosterone to [3H]17 beta-hydroxy-5 alpha-androstan-3-one (5 alpha-DHT) and to [3H]5 alpha-androstane-3 alpha (beta), 17 beta-diol was inhibited by unlabeled steroids in the following manner progesterone greater than testosterone greater than estradiol. Unlabeled 5 alpha-DHT did not inhibit [3H]testosterone metabolism indicating that product inhibition is not an important regulatory event. The antiandrogen cyproterone acetate did not inhibit the formation of 5 alpha-reduced metabolites of [3H]testosterone. All of the compounds used inhibited androgen binding to the classically defined cytoplasmic and nuclear androgen receptor.
Steroids 1984 Nov
PMID:The effects of various steroids on testosterone metabolism by the sexually mature rabbit epididymis. 654 32

Effects of metabolites of testosterone and of anabolic androgens on bone marrow and thymus of ovariectomized mice were studied. Steroids contained in capsules made of silastic tubing were implanted on the day of castration or were injected at the day of castration (Noralone and T.P.), lymphatic organs were examined two weeks later. It was found that testosterone, 5 alpha-DHT, 3 alpha-diol, Dianabole, T.P., and Noralone caused increases in the relative number of large cells and in activity of 20 alpha SDH in bone marrow. Concomitantly, these steroids caused a marked reduction in thymus cell number and an increase in the responsiveness of the thymus cells to Con A and PHA. The steroid 3 beta-diol increased marrow cell 20 alpha SDH activity but did not affect the thymus cell number. Other steroids tested, Ad-dione 3 alpha or 3 beta-androsterone, 5 beta-DHT, epitestosterone, and progesterone had no effect on thymus or bone marrow.
 ...
PMID:Effects of testosterone metabolites and of anabolic androgens on the bone marrow and thymus in castrated female mice. 657 19

The comparative ability of granulosa cells and theca of the hamster preovulatory follicle to produce androgens in vitro from endogenous and exogenous substrates was assessed. The results indicate that theca are the major source of follicular androstenedione, but that the granulosa cells may be the major source of follicular testosterone. Theca and granulosa cells accumulate comparable amounts of dihydrotestosterone from exogenous androstenedione and testosterone and both may be a significant source of follicular DHT. LH stimulates the conversion of progesterone and 17 alpha-OH progesterone to androstenedione, testosterone and DHT in theca. LH does not stimulate the conversion of androstenedione to testosterone or DHT, and that of testosterone to DHT in either granulosa cells or theca. FSH, in granulosa cells but not in theca, stimulates the conversion of adrostenedione to testosterone but it has no effect in DHT accumulation from exogenous testosterone.
Steroids 1980 Jan
PMID:The source of follicular androgens in the hamster follicle. 676 81

We have investigated the action of high doses of androgens in Gobius niger L., a marine teleostean fish, by characterizing specific steroid receptors in liver and by assaying the plasma vitellogenin concentration under different hormonal treatments. Estrogen and androgen receptors were characterized in the liver nuclear extracts according to their binding specificity. The maximum binding capacity was 25 fmoles/mg protein for the estrogen and androgen receptors. In vivo, high doses of DHT()increased the concentration of plasmatic vitellogenin as assayed by immunodiffusion while low doses were inefficient. In spite of a similar number of estrogen and androgen nuclear receptor sites (25 fmoles/mg protein), DHT was at least 70 fold less active than E2 on yolk protein and vitellogenin induction both in male and female Gobius niger. In addition, the antiestrogen tamoxifen, which was inactive by itself, inhibited the E2 and the DHT induced accumulation of vitellogenin. Progesterone (2 mg/fish) was also totally inactive in inducing vitellogenin. We conclude that the induction of vitellogenin by DHT is mediated by the estrogen receptor rather than by the androgen receptor. In addition to the estradiol induced protein in rat uterus and to other estrogenic responses obtained by androgens in mammary cancer, fish vitellogenin is another estrogen regulated protein which can be induced by high doses of androgens.
Steroids 1980 Mar
PMID:Effect of androgen mediated by the estrogen receptor of fish liver: vitellogenin accumulation. 676 82

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

20 beta-Hydroxy-5 alpha-pregnan-3-one (HPO) is a competitive inhibitor of reduction by 3 alpha/20 beta-hydroxysteroid dehydrogenase (3 alpha/20 beta-HSD; E.C.1.1.1.53) of 17 beta-hydroxy-5 alpha-androstan-3-one (DHT; 3 alpha-activity; Ki = 4.6x10(-5)M), and of 6 beta-acetoxyprogesterone (6 beta-AP; 20 beta-activity; Ki = 4.34x10(-5)M). HPO and DHT inhibit affinity alkylation of 3 alpha/20 beta-HSD by 6 beta-bromoacetoxyprogesterone (6 beta-BAP). The facts that 1) enzyme 3 alpha-activity and 20 beta-activity are both competitively inhibited by HPO with practically identical Ki-values, 2) 6 beta-BAP is solely a 20 beta-activity substrate for 3 alpha/20 beta-HSD, 3) one mole of 6 beta-BAP reacts with one mole of 3 alpha/20 beta-HSD to simultaneously inactivate 3 alpha- and 20 beta-activity, and 4) inactivation of 3 alpha/20 beta-HSD by 6 beta-BAP is inhibited by DHT (a C19-steroid) or HPO (a C21-steroid), support the view that the same active site of 3 alpha/20 beta-HSD possesses both 3 alpha- and 20 beta-activity. Bifunctional activity at the same active site is considered for other steroid-specific enzymes in female mammalian reproductive systems.
Steroids 1980 Jan
PMID:Bifunctional enzyme activity at the same active site: competitive inhibition kinetics with 3 alpha/20 beta-hydroxysteroid dehydrogenase. 692 16

High pressure liquid chromatography (HPLC) was used to determine 3H-estramustine (estradiol-17 beta 3N-bis-[2-chlorethyl] carbamate), 3H-17 beta-hydroxy-5 alpha-androstan-3-one (3H-dihydrotestosterone or 3H-DHT), 3H-estradiol-17 beta (3H-E2) and 3H-3 beta-hydroxy-5-pregnen-20-one (3H-pregnenolone) binding in 50(2) microliter of cytosol utilizing a column which separates proteins in the molecular weight range of 2,000 to 70,000 daltons. The rat prostate contains a protein in considerable concentration and with the highest affinity for estramustine (375,000 dpm 3H-estramustine per mg. cytosol protein) among the substances tested. Operationally, we have named this protein "estramustine binding protein" (EBP), though it is very likely similar to other previously described prostatic proteins (e.g., alpha-protein, prostatein, prostatic binding protein). The sensitivity of the HPLC method disclosed EBP-like proteins, but in much lesser concentrations, in some of the other tissues tested. The concentration of these proteins in the human and baboon prostates was much lower (average for the baboon cranial lobe 4800 dpm/mg cytosol protein, with a somewhat higher value for the caudal lobe) than that in the rat gland. The amount of the EBP-like protein was higher in prostatic cancer than in that of benign prostatic hypertrophy (BPH) (range 9350--25,900 vs. 2200--18,900 dpm/mg cytosol protein). In the human, the highest value was found in one normal prostate tested (106,000 dpm/mg cytosol protein).
Steroids 1981 May
PMID:Estramustine binding in rat, baboon and human prostate measured by high pressure liquid chromatography. 725 14


<< Previous 1 2 3 4 5 6 7 Next >>