Androgen Binding Components Research Articles

Hormonal Contraception and the Brain: Examining Cognition and Psychiatric Disorders

Background:The combined oral contraceptive pill (OC), containing synthetic estrogens and progestins, is used by millions of women worldwide, yet little is known about its effects on cognition or on psychiatric disorders. The progestin component of OCs determines their androgenicity, i.e. whether the OC has androgen binding components with masculinising effects or antiandrogenic components with feminising effects.Objective:The present review discusses the literature surrounding OC use and cognition in healthy women. Given the important role that sex hormones play in psychiatric disorders, we also consider the influence of OCs on symptoms of schizophrenia, post-traumatic stress disorder, depression, bipolar disorder, anxiety disorders and indirectly, sleep quality.Results:Research has shown that while there are no differences between OC users and non-users, androgenic OCs enhance visuospatial ability and anti-androgenic OCs enhance verbal fluency. Little is known about OCs effects on other cognitive domains, such as memory and executive function. There is little research examining OC use in schizophrenia, post-traumatic stress disorder, bipolar disorder and anxiety disorders. There is some evidence that OC use is associated with depression, however the exact causality of this association remains to be verified.Conclusion:We maintain that future studies need to address several methodological limitations, such as separating OCs based on androgenicity to avoid the masking effects that occur when various OCs are considered as one group. As this review highlights several significant effects of OC use on the brain, the implications of OC use needs to be considered in future research.

Analysis of androgen-and progestin receptors in human endometrial carcinomas.

Androgen-binding components labeled with a tritiated synthetic androgen, methyltrienolone(R1881) were analysed in human endometrial carcinoma cytosols. Tritiated R1881 binding consists of 3 components; high-affinity, low capacity androgen binding (androgen receptor), possible progestin receptor and non-specific androgen binding. The existence of androgen receptor in the tumor suggests a direct effect of androgen in endometrial carcinoma, possibly, through its interaction with the androgen receptor. Androgen- and progestin receptors were further measured in the cytosols of 20 endometrial carcinomas from 19 non-treated patients. The concentrations of the androgen receptors in the endometrial carcinomas were, in decreasing order; highly differentiated [21.5 + 5.4(SEM) fmoles/mg protein, N=10], moderately differentiated [3.4 + 2.7, N=3] and poorly differentiated tumors [2.5 + 1.4, N=7]. The concentrations of progestin receptors in the highly differentiated, moderately differentiated and poorly differentiated tumors were 291 + 79.7 (N=10), 52.6 + 34.1(3) and 14.7 + 6.8(7), respectively. Androgen- and progestin receptors in endometrial carcinomas would appear to correlate with histologic grade of differentiation of the tumor.

Characterization of a high-affinity, low-capacity androgen binding protein in human term placental cytosol.

A high-affinity, low-capacity androgen binding component in human placental cytosol was characterized. (3H)-R1881, a synthetic androgen, was used as radioactive ligand for characterization and quantification of this placental androgen binding component. Various naturally occurring as well as synthetic steroids were first investigated for their in vitro stability under receptor assay conditions (i.e., an overnight incubation at 4 degrees C). Only the synthetic steroids were found to be metabolically stable. The rate constant of dissociation was found to be 6.42 X 10(-4) s-1 (on the basis of k-1 the rate constant of association was 1.27 X 10(5) M-1 s-1). The concentration of androgen binding protein was measured in 50 human term placentae. The mean concentration was 169 +/- 132 fmol/mg protein, and the average Kd was 5.07 +/- 2.2 X 10(-9) M. Placentae of female fetuses contained significantly higher concentrations (219 +/- 140 fmoles/mg protein) than those of male fetuses (115.2 +/- 101 fmoles/mg protein). The (3H)-R1881-androgen binding protein complex exhibited a sedimentation coefficient of 4S under low salt conditions. The binding site was only specific for androgens and progestins but not for steroids of other classes.

Androgen-binding components of human semen.

Androgen-binding components were detected in human semen, using the dextran-coated charcoal method. Pre- and postvasectomy semen samples did not show significant differences in ability to bind dihydrotestosterone. Electrophoresis conducted in polyacrylamide gels in which tritiated dihydrotestosterone had been incorporated disclosed the presence of androgen-binding protein with properties characteristic of the ABP of Sertoli cell origin in ram semen but ABP was not detectable in human semen, even after concentrating it two or four fold. The binding of dihydrotestosterone was slightly greater in the later portion of split-ejaculate samples, but binding was found in the earlier fraction and in prostatic fluid, suggesting that androgen-binding components enter human semen with secretions of the prostate and seminal vesicle glands. It was concluded that the extent of androgen-binding by human seminal fluid is not a measure of Sertoli-cell function.

Evidence that human placenta is a site of sex hormone-binding globulin gene expression

The presence of an androgen-binding component in placenta was investigated in vitro using a tissue culture system of human placental explants. Explants of trophoblastic tissue from normal term placentas were kept in culture under appropriate conditions for at least 48 h in a serum-free medium. The existence of an androgen-binding protein was explored by binding assays, immunohistochemistry studies and Northern blot analyses of placental mRNA. Steady-state polyacrylamide gel electrophoresis and Scatchard plot analyses revealed the presence of a high affinity specific binding component for 5α-dihydrotestosterone in cultured placenta. Immunohistochemical studies performed on intact placenta and on Percoll-gradient purified trophoblastic cells demonstrated the presence of specific immunoreactivity in the cytoplasm of syncytial cells. Northern blot analyses of placental mRNA showed a single hybridizable 32P-labeled human sex hormone-binding globulin (SHBG) cDNA band of approx. 1.6 kb which was identical in size to that obtained with liver mRNA. The results strongly suggest the placenta as an origin of SHBG and point out this tissue as an additional site of SHBG synthesis during pregnancy.

Characteristics of the calf uterine androgen receptor

The highest molecular weight form of the calf uterine androgen receptor separates as an 11S form in glycerol gradients. This “cytosolic” receptor, prepared in the presence of molybdate, polyethyleneimide and low ionic strength, dissociates into 9S and 7.2S forms with increasing KCl concentration. A 4.5S androgen binding component appears as the predominant form of the receptor in the absence of polyethyleneimide and this unit quantitatively converts to a stable 3.5S form in the absence of molybdate. Renaturation of partially purified protein, separated by SDS-PAGE electrophoresis, demonstrates the presence of an androgen binding component in the 110 kDa region of the gel. This renatured protein separates as a 4.5S component in glycerol gradients and has a Stokes radius of 6 nm. Photoaffinity labelling of partially purified receptor preparations, followed by SDS-PAGE electrophoresis, reveals the presence of an androgen binding component having a molecular weight of 115 kDa. The binding characteristics and specificity of the receptor binding to R1881 have been studied and a DHT-affinity chromatography resin used to purify the receptor.

Androgen binding to ammonium sulfate precipitates of human adipose tissue cytosols

Although androgens are believed to influence the distribution of human adipose tissue and have been detected in human fat, receptors for these sex hormones have yet to be identified. These studies demonstrate that a high-affinity, limited-capacity binding component for the synthetic androgen methyltrienolone (R1881) exists in ammonium sulfate precipitates of human adipose tissue cytosols. The equilibrium dissociation constant (K d = 0.1 to 0.4 nmoll L, n = 6) and the number of binding sites (2 to 26 fmollmg protein, n = 22) are consistent with those reported for androgen receptors in rat prostate, human prostatic carcinoma, MCF-7 cells, and baboon myocardium. The relative steroidinding specificities of the human adipose tissue androphile (R1881~5α-ihydrotestosterone>testosterone> estradiol~progesterone>dexamethasone) are similar, but not identical, to those reported for androgen receptors in rat prostate (Rl88l>5α-dihydrotestosterone~testosterone>estradiol>progesterone> cortisol) and baboon myocardium (R1881>5α-dihydrotestosterone.testosterone>progesterone> estradiol>cortisol). The function of the androgen-binding component in human adipose tissue is not known. (Steroids 55:410–415, 1990)

Testosterone micromilieu in staged rat seminiferous tubules

Endogenous testosterone concentrations in rat seminiferous tubules were measured in relation to different stages of the cycle of the seminiferous epithelium. For this purpose, the seminiferous tubules were mechanically separated from the interstitial tissue on a cooled (1°C) petri dish under a stereomicroscope without added medium. After recognition of the stages of the cycle by transillumination, the specimens were rapidly transferred by dry forceps into test tubes for testosterone radioimmunoassay. The results of the dry dissection method were compared with measurements on tubules that were kept after separation in phosphate buffered saline (PBS, pH 7.4), in order to reveal the possible leakage of testosterone from the tubules. The maximal concentration of testosterone per unit length of seminiferous tubule was found in stages VII and VIII of the cycle (288 ± 60 fmol/cm, mean ± SEM, n = 12), and the minimal in stages IX–XII (219 ± 57 fmol/cm, P < 0.01). If the levels were correlated with unit volumes of the seminiferous tubules, identical concentrations of testosterone (521–542 fmol/mm 3, approx. 500 nmol/l) were found in the different stages of the cycle. Despite the similarity of testosterone concentrations in the different parts of the seminiferous tubules the local concentrations of biologically active (i.e. free) testosterone may be modulated by extracellular and intracellular androgen binding components.

Post-natal patterns of plasma androgen-binding activity in Djungarian (Phodopus sungorus) and golden (Mesocricetus auratus) hamsters

The binding of sex steroids to plasma proteins was examined in post-natal Djungarian and golden hamsters. With dihydrotestosterone or testosterone as ligands, steady-state polyacrylamide gel electrophoresis revealed 2 androgen binding components in the plasma of young Djungarian hamsters of both sexes. The fast-moving component exhibited a low affinity and high capacity for androgens and corresponded to albumin in stained gels. In contrast, the slow moving component was a beta-globulin with high affinity (Ka = 10(9) M-1) and low capacity for androgens, and was identified as a specific sex steroid-binding protein (SBP; also SHBG). This SBP did not bind oestrogens or corticosteroids and was electrophoretically distinct from corticosteroid-binding globulin (CBG). In addition, this protein did not appear to be of testicular origin because it was present in immature females and in immature males that had been castrated for 8 days. Plasma concentrations of SBP in males as measured by a diethyl-aminoethyl-cellulose binding assay were low at birth, became significantly elevated shortly thereafter when plasma androgen values were also elevated, and subsequently fell to low levels during puberty. These changes follow the same general pattern that has been described for other mammals, including humans, during this period of reproductive development. Although the significance of elevated SBP concentrations during prepuberty has yet to be determined, it appears that the increased concentrations of high-affinity androgen binding in the plasma of Djungarian hamsters plays a role in the asynchronous pubertal development of the testes and accessory organs which occurs in this species. The post-natal SBP pattern in females was similar to that observed in males. Plasma SBP levels were low or undetectable in adults of both sexes. As previously described for adult golden hamsters, the plasma of post-natal male and female golden hamsters lacked a specific SBP: androgen binding in this species is apparently limited to albumin and CBG.

Purification and immunochemical characterization of the cytoplasmic androgen-binding protein of rat liver.

The cytoplasmic androgen-binding (CAB) protein of the male rat liver has been implicated to play a role in the androgen-dependent regulation of alpha 2u-globulin synthesis. The liver of the adult male rat contains about 50 fmol of specific high-affinity androgen-binding activity per milligram of total cytosolic protein. Photoaffinity labeling with [3H]R-1881 followed by SDS-polyacrylamide gel electrophoresis and autoradiography shows that the CAB is a 31-kilodalton protein. By means of DEAE-cellulose chromatography and preparative SDS-polyacrylamide gel electrophoresis, we have purified the CAB protein to electrophoretic homogeneity and have raised polyclonal rabbit antiserum that is monospecific to this protein. In the sucrose density gradient, the antiserum reacted with the androgen-binding component of the male liver cytosol prelabeled with tritiated dihydrotestosterone. Western blot analysis of the liver cytosol showed that the antiserum recognizes only the 31-kDa androgen-binding component. Such immunoblotting also showed that unlike the young adult, the androgen-insensitive states during prepuberty and senescence are associated with a marked reduction in the hepatic concentration of the immunoreactive CAB protein. No immuno-chemical cross-reactivity between CAB and another androgen-binding component of Mr 29K (which is associated with androgen insensitivity during prepuberty and senescence) was observed. The latter finding favors the possibility that 31- and 29-kDa androgen-binding components may have distinct sequence structure.

Presence of androgen receptors in the hen hypothalamus and pituitary.

Soluble and insoluble fractions in a hypotonic buffer solution of hypothalamic-preoptic and median eminence areas, and of the anterior pituitary of the hen were found to contain a specific androgen binding component having the properties of a receptor. Administration of testosterone in vivo caused a marked decrease in specific [3H]R1881 (a synthetic androgen) bindings in the soluble fraction with a concomitant increase in the bindings in the insoluble fraction, whereas the sum of the bindings did not change. A similar relationship between the bindings of the two fractions was also observed during an ovulatory cycle. The results may provide an evidence for a direct action of androgens on the hen hypothalamus and pituitary.

Effect of kallikrein on the Sertoli cell function.

The effect of kallikrein on the Sertoli cells was investigated to determine the rat testicular androgen binding component (ABC = androgen binding protein + androgen receptor) concentration using the dextran-coated charcoal method. The results showed that the concentrations of testicular ABC were increased significantly by the administration of kallikrein to levels approaching those seen after stimulation by LH-RH or FSH. Therefore, it is suggested that kallikrein has an effect that influences the Sertoli cells directly or indirectly.

Cytoplasmic androgen binding protein of rat liver: molecular characterization after photoaffinity labeling and functional correlation with the age-dependent synthesis of .alpha.2u-globulin

The liver of the mature male rat contains a moderate affinity (Kd = 10(-8)M), low-capacity, cytoplasmic androgen binding protein (CAB) whose appearance during puberty and disappearance during senescence correlate with the androgen-dependent synthesis of alpha 2u-globulin. Molecular properties of CAB were examined by photoaffinity labeling with tritiated methyltrienolone (R-1881), a synthetic androgen, and by its localization within the hepatocytes which are competent to produce alpha 2u-globulin. Photoaffinity labeling of the liver cytosol derived from postpubertal male rats, followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and fluorography, showed a predominant androgen binding band corresponding to Mr 31,000. This 31-kilodalton (kDa) binding component was conspicuously absent in the liver of androgen-insensitive prepubertal and senescent male rats and in adult male rats treated with estradiol-17 beta. In addition, unlike the cytoplasmic extract, the nuclear lysate of the male rat hepatocytes did not contain the 31-kDa androgen binder. Disappearance of the 31-kDa androgen binding band from the cytosolic fraction of androgen-insensitive animals was associated with a concomitant appearance of a minor androgen binding component of apparent Mr 29,000. The livers of postpubertal male rats normally contain two subpopulations of hepatocytes, only one of which is highly active (competent) in alpha 2u-globulin synthesis. Separation of these two subpopulations through a fluorescence-activated cell sorter followed by whole cell labeling showed more than a 2-fold higher uptake of R-1881 by the competent cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Estrogen synthesizing rare malignant brenner tumor of the ovary with the presence of progesterone and androgen receptors in the absence of estrogen receptors

A case of a malignant Brenner tumor of a postmenopausal woman presenting with vaginal bleedings is described. Clinical and laboratory findings demonstrated estrogenic secretory function and action. The presence of aromatase activity based on in vitro tumor microsomal metabolism of androgen to estrogen is described. Tumor cytosol contained progestin and androgen binding components in the absence of estrogen binding activity. Estrogen binding activity was undetectable both by biochemical as well as histochemical assays.

Multiple androgen binding components in prostatic epithelial cells as evidenced by a whole cell assay system

Multiple androgen binding components in prostatic epithelial cells as evidenced by a whole cell assay system

The androgen receptor in normal human foreskin

Abstract Use of glycerol and the protease inhibitor phenylmethylsulfonyl fluoride resulted in a fourfold increase in the yield of androgen receptor from human neonatal foreskin and a tenfold increase in stability of this receptor. The general physical properties of the androgen-binding component isolated from the cytosol of human neonatal foreskin were found to be consistent with those previously reported for androgen receptors. The synthetic androgen methyltrienolone (R1881) was bound with high affinity (a mean dissociation constant of 0.51 nmol/L) and low capacity (5.6 fmol/mg of protein); maximum binding required 4 hours. Affinity of the receptor was highest for R1881 followed by dihydrotestosterone, testosterone, and progesterone. 17β-Estradiol showed little or no competition. The receptor exhibited a change of sedimentation coefficient from 8S to 4S upon treatment with 0.1 mol/L potassium chloride. Isoelectric focusing demonstrated the existence of two molecular species with apparent isoelectric points of 7.2 and 5.7.

The androgen receptor in normal human foreskin: I. Stabilization and identification of two receptor subunits

Use of glycerol and the protease inhibitor phenylmethylsulfonyl fluoride resulted in a fourfold increase in the yield of androgen receptor from human neonatal foreskin and a tenfold increase in stability of this receptor. The general physical properties of the androgen-binding component isolated from the cytosol of human neonatal foreskin were found to be consistent with those previously reported for androgen receptors. The synthetic androgen methyltrienolone (R1881) was bound with high affinity (a mean dissociation constant of 0.51 nmol/L) and low capacity (5.6 fmol/mg of protein); maximum binding required 4 hours. Affinity of the receptor was highest for R1881 followed by dihydrotestosterone, testosterone, and progesterone. 17β-Estradiol showed little or no competition. The receptor exhibited a change of sedimentation coefficient from 8S to 4S upon treatment with 0.1 mol/L potassium chloride. Isoelectric focusing demonstrated the existence of two molecular species with apparent isoelectric points of 7.2 and 5.7.

Studies of the human testis. XIX

Human testosterone-oestradiol-binding globulin (hTeBG) was purified from pregnancy serum by ammonium sulphate precipitation, preparative flatbed electrofocusing, Concanavalin A-Sepharose affinity chromatography, Sephadex G-150 gel filtration, DEAE-Sephadex chromatography and preparative polyacrylamide gel electrophoresis. The yield was 0.3 mg of hTeBG with a specific acitivity of 1.1 nmoles DHT bound per mg. An antiserum to TeBG was raised in rabbits. Anti-hTeBG IgG was separated from rabbit TeBG by DEAE-Affi-Gel-Blue chromatography. Anti-hTeBG was titrated using protein A-Sepharose which quantitatively binds IgG and therefore bound [3H]DHT-hTeBG-anti-TeBG complexes. The androgen binding components from human testis were separated on Concanavalin A-Sepharose columns into excluded and retained fractions. The antibody bound both testis fractions with titration curves which paralleled that of TeBG, indicating that these androphilic proteins share common immunodeterminants with hTe-BG. The possibility that these testicular proteins are identical in amino acid sequence to TeBG and differ only in carbohydrate content will require further verification. Finally, these results indicate that antibodies to TeBG can be used to study human testicular androgen-binding protein.

Progestin- and androgen-binding components in a human granulosa-theca cell tumor

Macromolecules which bound progesterone (P), medroxyprogesterone acetate (MPA), and dihydrotestosterone (DHT) have been identified in the cytoplasmic fraction of a human granulosa-theca cell tumor and partially characterized. Bound [ 3H]P sedimented at the 3.6 S region of the sucrose gradients, whereas bound [ 3H]MPA was observed mainly in the 6 S region. P and MPA competed with each other for binding to these components. The specific MPA-binding sites were saturable and had a K a of 3.6 n M −1. Heating the tumor cytosol at 37 °C for 10 min diminished its progestin-binding activity. The DHT-binding components had sedimentation coefficients of 4.2 S and 6 S, and a K a of 0.4 n M −1. They were heat sensitive and were precipitable by protamine sulfate. Attempts to demonstrate specific binding of estrogens and glucocorticoids by this tumor cytosol were unsuccessful.

Evidence for an androgen binding component in human placental cytosol

A high-affinity, low-capacity androgen binding component is present in human term placental cytosol. A synthetic androgen tracer, [ 3H]-R1881, was bound by a single class of binding sites with a K d of 2.73 ± 1.25 × 10 −9 M and a concentration of binding sites of 157 ± 73 fmol/mg protein ( N = 20). In competitive binding studies, R1881, T, 5αT, androstenedione and DHEA, were active competitors, but not estradiol, progesterone or Cortisol. The [ 3H]-R1881 macromolecule complex exhibited a sedimentation coefficient of 4–5 S under low and high salt conditions, and the radioactive tracer was displaced by a 100-fold excess of unlabelled R1881. This binding component has characteristics of high-affinity, low-capacity, sedimentation behaviour and specificity, commonly attributed to androgen “receptors”.