Presence Of Progestin Receptors Research Articles

Progestagen nuclear binding sites in the male genital tract of the mouse, studied by autoradiography

Autoradiograms were prepared after injection of 125I progestagen (sp. act. 2200 Ci/mmol) to prepubertal and young adult mice. Nuclear concentration of radioactivity was found in smooth muscle cells at the beginning and the end of the deferent duct and in fibroblasts around the fusion of the deferent duct with the urethra. Nuclear labeling was enhanced in adult animals pretreated with oestradiol-valerate. In prepubertal mice nuclear labeling was more abundant than in adult mice and found in all smooth muscle cells of the deferent duct. No nuclear labeling was observed in other accessory sex organs. Nuclear labeling was prevented by injection of excess of unlabeled R5020. The presence of progestin receptors in smooth muscle cells of the deferent duct suggests a regulatory effect of progestin on contractions in analogy to progestin effects on oviductal and uteral smooth muscle cells. The presence of nuclear progestin receptors in the periurethral region may indicate an involvement of progestins in the etiology and regulation of benign prostate hyperplasia.

Steroid hormone binding in the harderian gland of birds: characteristics of the androgen, estrogen, and progestin receptors of Anas platyrhynchos and Gallus domesticus

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 ( K d = 2.4 and 1.6 n M), progestins (0.8 and 1.0 n M), and androgens (1.0 and 1.0 n M) 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.

Sex steroid receptors in human meningiomas.

Results of experiments on the presence of steroid receptors in a series of 67 meningioma tissues, which were derived from 64 patients are presented. All tissues were studied using dextran-coated charcoal adsorption and Scatchard plot analysis. Progestin receptors were present in a high concentration in more than 80% of the specimens. Very low concentrations of an oestrogen binding agent were found in a limited number of samples. Thus, most meningiomas contain high levels of progestin receptors in the virtual absence of oestrogen receptors. Relations were not observed between progestin receptor-content and the age and sex of the patients, or the location and the histological type of the tumour. The role and action of progestin on meningiomas is still unknown. The presence of progestin receptors, however, suggests that meningioma may be regarded as a true target tissue for progestins.