16-alpha-ethyl-21-hydroxy-19-nor-4-pregnene-3-20-dione and mibolerone

To examine antiestrogenic effects of danazol through the receptor system and to clarify its direct effects on the endometrium in vivo, we applied danazol jelly directly into the rabbit uterine cavity and measured uterine estrogen, progesterone and androgen receptors (ER, PR and AR, respectively). Danazol significantly reduced ER, PR and AR (p < 0.05). Treatment with receptor-blocking agents (RU 486 and oxendolone) showed that the decrease in the ER level showed a closer association with that in PR than with AR. These results indicate that danazol directly administered into the uterine cavity is absorbed by the endometrial tissue and exerts its antiestrogenic effects possibly through PR in the cells.

Topics: Animals; Chromatography, High Pressure Liquid; Danazol; Endometrium; Estradiol; Female; Hydrocortisone; Nandrolone; Pregnenediones; Progesterone; Rabbits; Receptors, Androgen; Receptors, Estrogen; Receptors, Progesterone; Triamcinolone Acetonide

Using synthetic peptides with sequences derived from specific regions of human estrogen (ER) and progesterone (PR) receptors, we have developed site-directed monoclonal and polyclonal antibodies to specific domains of these receptors. These antibodies interact specifically with the native (nondenatured) receptors and detect changes in the conformation of these proteins. Monoclonal antibody PR-AT 4.14 bound more tightly to PR-ORG 2058 complexes than to PR-7 alpha,17 alpha-dimethyl-19-nor-testosterone (7 alpha,17 alpha, DMNT; mibolerone) complexes, suggesting possible ligand-induced conformational changes in PR. In the absence of the antibody, PR-[3H]ORG 2058 complexes sedimented as 4S-5S entity on sucrose density gradients (SDG) containing 0.4 M KCl. In the presence of the antibody, PR-[3H]ORG 2058 complexes sedimented as 7-8S complexes. In contrast, at the same concentrations of antibody, PR-[3H]7 alpha,17 alpha, DMNT complexes sedimented at 4S-5S region in the absence of the antibody and as two populations in the presence of the antibody, suggesting that the antibody did not recognize all of the PR-7 alpha,17 alpha, DMNT complexes. To exclude the possibility that the inability of the antibody to recognize receptor-[3H]7 alpha,17 alpha, DMNT complexes was due to its binding to androgen receptors, unlabeled 5 alpha-dihydrotestosterone (5 alpha-DHT) (50 nM) was added to the incubation to inhibit 7 alpha,17 alpha, DMNT binding to androgen receptors. While PR-[3H]ORG 2058 complexes were immunoprecipitated in the presence of the antibody, PR-[3H]7 alpha,17 alpha, DMNT complexes were only partially immunoprecipitated, further confirming the results obtained with SDG.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Binding Sites, Antibody; Binding, Competitive; Blotting, Western; Breast Neoplasms; Cattle; Female; Humans; Nandrolone; Precipitin Tests; Pregnenediones; Protein Conformation; Rats; Rats, Sprague-Dawley; Receptors, Estrogen; Receptors, Progesterone; Uterus

19-Nor synthetic progestins undergo extensive metabolism at the target cells. The resulting metabolic conversion products interact with putative steroid receptors within the cells, and through those interactions, they may exert either agonistic, synergistic and antagonistic hormonal effects. Studies conducted in our laboratories have disclosed that norethisterone (NET) and D-(1) norgestrel (LNG), two widely used contraceptive progestins, are biotransformed to several A-ring reduced (dihydro and tetrahydro) derivatives. The resulting metabolites 5 alpha-dihydro NET (5 alpha-NET) and 5 alpha-dihydro LNG bind with relative high affinity to the progesterone and androgen receptors. To gain insight into the underlying molecular events mediating the mode of action of NET and its neutral metabolites, we have examined the expression of their biological effects at target organs by using the rabbit uteroglobin gene model and the beta-glucuronidase activity of the mouse kidney. The results of a series of experiments seem to indicate that the enzyme-mediated formation of the 5 alpha (trans A/B ring junction) NET derivative results in a significant diminution of its progestational and androgenic potencies. Furthermore, 5 alpha-NET acquire a potent anti-progestational/contragestational effect as assessed in the female rabbit. These results demonstrated that 5 alpha-reduction of 19-nor progestins exerts a paradoxical effect, at least in terms of their hormone-like effects. The overall data are in line with the concept that metabolism of synthetic progestins at hormone-sensitive organs modulates their mechanisms of action.

Topics: Animals; Binding, Competitive; Biotransformation; Female; Kidney; Kinetics; Mice; Mice, Inbred BALB C; Nandrolone; Norethindrone; Norgestrel; Pregnenediones; Progesterone Congeners; Rabbits; Receptors, Androgen; Receptors, Progesterone; Sexual Maturation; Steroids; Testosterone Congeners; Uteroglobin; Uterus

A series of experiments was carried out in immature female chicks and ducks to establish whether the avian Harderian gland contains specific receptors for sex steroids. Cytosol preparations of Harderian glands were submitted to hormone saturation analysis using radiolabeled estradiol, ORG-2058, and dimethylnortestosterone as ligands. In addition, the sedimentation characteristics of the hormone-receptor complexes were studied by ultracentrifugation of linear sucrose gradients. The presence of high affinity binding sites for estrogens (Kd = 2.4 and 1.6 nM), progestins (0.8 and 1.0 nM), and androgens (1.0 and 1.0 nM) was indicated in the chick and duck glands, respectively. The sedimentation coefficients were 7-7.5 S, 7-8 S, and 8 S for estrogen, progestin, and androgen receptor-ligand complexes, respectively. The concentration of the androgen receptor was significantly higher in chick than in duck Harderian glands whereas the estrogen and progestin receptor concentrations were similar in both species. A striking finding was the presence of progestin receptors, which apparently do not exist in the glands of many mammals. Priming with estrogens did not modify the concentration of ORG-2058 binding sites in either species studied, indicating that gland progestin receptor is not estrogen-regulated. Overall the data suggest intracellular mechanisms whereby circulating gonadal hormones regulate avian Harderian gland function.

Topics: Animals; Centrifugation, Density Gradient; Chickens; Cytosol; Ducks; Estradiol; Female; Harderian Gland; Nandrolone; Pregnenediones; Progesterone Congeners; Receptors, Androgen; Receptors, Estrogen; Receptors, Progesterone

In rat uterus and prostate, 7 alpha, 17 alpha-dimethyl-19-nortestosterone (DMNT) binds to the androgen receptor specifically and with high affinity. However, this steroid does not bind to glucocorticoid receptors, since it does not displace binding of [3H]triamcinolone acetonide in calf thymus cytosol. In calf uterine and human breast tumor cytosols DMNT binds to the androgen and progesterone receptors, since binding of [3H] DMNT is displaced by unlabeled 16 alpha-ethyl-21-hydroxy-19-nor-4-pregnene-3, 20-dione triamcinolone acetonide, and 5 alpha-dihydrotestosterone (DHT). Conversely, binding of [3H]16 alpha-ethyl-21-hydroxy-19-nor-4-pregnene-3,20-dione is effectively competed for by unlabeled DMNT but not by DHT. The observed differences in binding of [3H]DMNT to rat and calf uterine cytosols suggest the species specificity of progesterone receptors. Unlike DHT, DMNT has no appreciable binding to human sex-steroid binding globulin. These findings suggest DMNT as a suitable ligand for measurement and characterization of androgen receptors in rat and human prostate.

Topics: Animals; Blood Proteins; Breast; Cattle; Cell Nucleus; Cytosol; Dihydrotestosterone; Estrenes; Female; Humans; Male; Metribolone; Nandrolone; Pregnenediones; Prostate; Prostatic Hyperplasia; Rats; Rats, Inbred Strains; Receptors, Androgen; Receptors, Progesterone; Substrate Specificity; Uterus