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

Methyltrienolone (R 1881 - 17beta-hydroxy-17alpha-methyl-estra-4,9,11-trien-3-one) binds specifically to androgen receptor in rat prostate cytosol where, unlike androstanolone, it is not metabolized. By exchanging bound endogenous hormone in rat prostate cytosol with labelled R 1881, it is possible to measure total (free anc occupied) binding sites. This assay method has also been applied to the measurement of androgen receptor sites in human benign prostatic hypertrophy where R 1881 has the added advantage of not being bound by any contaminating plasma protein (sex hormone binding protein).
Steroids 1976 Apr
PMID:Assay of androgen binding sites by exchange with methyltrienolone (R 1881). 5 52

Methyltrienolone (R 1881 - 17beta-hydroxy-17alpha-methyl-estra-4, 9, 11-trien-3-one) binding to rat ventral prostate cytosol has a specificity typical of an androgen receptor. In human benign prostatic hypertrophy (BPH) tissue, the specificity of [3H] R 1881 binding is different from that measured in rat prostate: progesterone and R 5020 (17, 21-dimethyl-19-nor-4, 9-pregnadiene-3, 20-dione) being more potent while 19-nortestosterone is less potent competitor. Moreover, the synthetic progestin [3H] R 5020 binds to BPH tissue with a similar specificity. These data suggest the presence of progestin binding components or of an atypical androgen receptor in human BPH cytosol.
Steroids 1976 Oct
PMID:Binding of [3H] methyltrienolone (R 1881) in rat prostate and human benign prostatic hypertrophy (BPH). 6 5

The presence of androgen-binding activity in cytosol prepared from the major anatomical segments (caput, corpus, and cauda) of the epididymis of castrated sexually mature rabbits has been demonstrated. A portion of this binding activity is likely to be the epididymal androgen receptor. When epididymal cytosol from adult castrated rabbits is analyzed on low-ionic strength (0.01 MKCl) sucrose gradients, two peaks of macromolecular binding could be detected, one congruent to 4.6S and one congruent to 8S. On gradients containing 1.0 M KCl, only one sedimenting form congruent to 4.6S could be demonstrated, suggesting that the 8S component is composed of aggregates. If cytosol was preincubated with labeled androgen, followed by an incubation with unlabeled androgen, and subsequently analyzed for binding on low-ionic strength gradients, only the congruent to 8S peak could be detected, indicating that most of the binding in the congruent to 4.6S region was rapidly dissociable. This suggests that binding in this region was to moieties other than receptor. Since androgen binding proteins (ABP) of testicular origin would have been cleared from the epididymis at the timepoints that we concentrated on for most of these studies, the 4.6S binding probably represents the association of androgen with plasma testosterone binding globulin (TeBG). The binding of androgen to the receptor can be inhibited by cyproterone, while this antiandrogen does not inhibit binding to either ABP or TeBG at the concentration used.
Steroids 1975 Apr
PMID:Androgen binding to cytosol prepared from epididymides of sexually mature castrated rabbits: evidence for a cytoplasmic receptor. 16 97

Ammonium sulfate precipitation has been used for the separation of bound and free steroids in rat prostate and mouse kidney cytosol equilibrated with tritiated androgens. A high affinity, low capacity binding protein has been identified in the 35% saturation precipitate. Biochemical and physiological data indicate that this protein is identical with the previously described 8-10 S androgen receptor. It has been demonstrated that this receptor protein binds 17 beta - hydroxy-5alpha-androstan-3-one (DHT) and testosterone in both tissues. The apparent dissociation constant (Kd) of the prostatic receptor for DHT and of the renal receptor for testosterone is 1-2 nM. The number of binding sites equals 57 and 23 fmoles/mg protein in prostate and kidney respectively. Dterminations of apparent inhibition constants (Ki) for 26 steroidal and non-steroidal compounds suggest that the binding sites in these tissues is similar or identical.
Steroids 1975 Aug
PMID:Ammonium sulfate precipitation as a tool for the study of androgen receptor proteins in rat prostate and mouse kidney. 17 5

A microassay utilizing R 1881 (methyltrienolone) has been developed for the measurement of androgen receptor sites in the cytosol and nuclear extract of human prostatic tissue. Binding of R 1881 to the progesterone binding molecule in cytosol was eliminated by the addition of triamcinolone acetonide. Utilizing a six tube, single point assay, the number of binding sites estimated in nuclear extract averaged 95% of the number measured by a full 7 point Scatchard analysis; the number estimated by the microassay in cytosol averaged 91%. When the single point assay was applied to needle biopsy specimens (200 mg of tissue), the estimated number of binding sites in nuclei averageed 83% of the number measured in bulk tissue (2 grams) utilizing a 7 point Scatchard analysis; the number in cytosol estimated by the microassay on needle biopsy specimens averaged 73%. It is hoped that this technique may be useful in correlating receptor content with hormonal responsiveness in men with metastatic carcinoma of the prostate.
Steroids 1979 Apr
PMID:A microassay for the measurement of androgen receptors in human prostatic tissue. 44 31

Postmitochondrial supernatant (PMS) (1) has been prepared from the homogenate of rat seminal vesicles and the characteristics of the binding reaction of 5alpha-dihydrotestosterone (DHT) to the cytoplasmic androgen receptor have been studied using a charcoal adsorption procedure. At 0 degrees C apparent equilibrium of binding is reached between 60 and 90 min of incubation but no exchange of bound (3H)DHT can be observed in the presence of a 100-fold excess of unlabelled DHT. Saturation analysis shows a single class of independent binding sites for DHT with an apparent dissociation constant of 1 nM at 0 degrees C and 2 nM at 25 degrees C. Concentration of binding sites is in the range of 25-80 fmoles/mg protein. When not occupied by DHT the receptor molecules are inactivated spontaneously following first order reaction kinetics. A rate constant of 0.27 hours-1 at 0 degrees C was determined for the inactivation reaction. In the (3H)DHT-binding reaction testosterone and 19-nortestosterone are even more efficient competitors than unlabelled DHT, while hydrocortisone does not compete at all. On the other hand significant binding of (3H) testosterone could not be demonstrated. The (3H)DHT-receptor complex is precipitated from the cytosol by 0 to 33% saturation of ammonium sulphate and sediments as a single, 3.1 S peak in sucrose gradients prepared in 0.4 M NaCl.
Steroids 1977 Dec
PMID:Characterization of the cytoplasmic androgen receptor of rat seminal vesicle. 61 40

In the immature rat uterus, occupation of the androgen and estrogen receptor sties after injection of 5 alpha dihydrotestosterone (DHT = 17beta - hydroxy-5alpha-androstan-3-one) were compared to the biological responses induced by the androgen on protein synthesis. Injection of 100 mug DHT induced a maximal occupation of androgen receptor sites (RA) but was totally ineffective in translocating the estrogen receptor sites and in increasing general protein synthesis. Conversely, high doses of androgen (greater than or equal to 3 mg) translocated the estrogen receptor (RE) and stimulated general protein synthesis. In addition, these high doses induced a specific uterine protein undistinguishable from that induced by estradiol treatment (IP). These results strongly suggest that the uterotrophic response of the uterus to androgen is correlated with the nuclear transreceptor which is present in much smaller amounts.
Steroids 1977 Jan
PMID:Androgens on the estrogen receptor. II--Correlation between nuclear translocation and uterine protein synthesis. 84 15

In the present study, "in vitro" evidences are shown for the existence of a highly active 3alpha-hydroxysteroid dehydrogenase in the crude cytosol of rat muscle homogenates; the use of 5alpha-dihydrotestosterone (DHT) is therefore compromised in receptor binding measurements because of its extensive metabolism. The synthetic anabolic androgen, methyltrienolone (MT) palliates this disadvantage of DHT. Both steroids, as well as testosterone, appear to be bound to an 8 - 8.5 S androgen receptor on sucrose density gradient. The androgen receptor in the vastus and the levator ani bulbocavernosus complex (LA/BC) shows similar association constants, but the number of binding sites in LA/BC is about 5 times higher than in vastus. Otherwise, the total number of muscle androgen receptors seems to be invariant in adult and aged rats. The binding to these macromolecules can thus be measured "in vitro" provided specific and sensitive methods are utilized.
Steroids 1977 Feb
PMID:Determination of rat muscles androgen-receptor complexes with methyltrienolone. 84 21

Skeletal muscle homogenate of prepuberal, adult uncastrated or short-(1-4days) or long-term (20days) castrated male and female rats was incubated at 0degreesC iwth highly labeled (3H)5alpha-dihydrotestosterone (1) or (3H) testosterone. labeled (3H)5alpha-dihydrotestosterone (1) or 3H) testosterone. After incubation bound and free hormone in the 100,000 g cytosol were separated by agargel electrophoresis at low temperature. Furthermore, the percentage distribution of the main metabolites found in the cytosol was analyzed by thin-layer chromatography. Two androgen binding proteins could be found: One with high affinity (apparent dissociation and constant (Kd)= 1.4 - 6.4X10(-9)M) low capacity (receptor), the other with relative low affinity high capacity. The physico-chemical characteristics of the androgen receptor in the rat skeletal muscle cytosol are similar if not identical to those which have been described for the androgen receptor in the prostate and other androgen dependent organs. However, the amount of available 5alpha-DHT-binding sites in the skeletal muscle is about 60 times and 7 times lower than in the prostate and bulbocavernosus/levator ani muscle, respectively. No essential androgen metabolism occurs in vitro at 0degreesC in the skeletal muscle.
Steroids 1976 Aug
PMID:Characterization of the androgen receptor in the skeletal muscle of the rat. 97 39

On solvolysis of Westphalen-type steroids with a leaving group in the position 6 beta (e.g., 2), products of elimination (followed by rearrangement and fragmentation of the steroid skeleton) were prepared (e.g., 4 and 5). These products were subsequently converted to suitable analogs of the compound, which has been reported to promote hair growth (1). Compounds 11 to 13 exhibited strong antiandrogenic activity in vivo; however, this activity could not be interpreted either in terms of inhibition of 5 alpha-reductase or by strong binding to an androgen receptor.
Steroids 1992 Sep
PMID:Antihormonal properties of some new A-homo-B, 19-dinor steroids of the androstane series. 145 64


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