Effect of flutamide on hepatic cytosolic methyltrienolone (R1881) binding kinetics and testosterone responsive hepatic drug and steroid metabolism in the adult male rat

Flutamide was used to investigate the mechanism involved in androgen responsive hepatic microsomal drug and steroid metabolism. We compared the antiandrogenic action of flutamide on the prostate to its effect on testosterone responsive hepatic microsomal benzo[a]pyrene hydroxylase (BPH) and testosterone reductase (TR) activities. Male Wistar rats, castrated as adults, were treated with 5 mumoles.kg-1.day-1 of testosterone enanthate subcutaneously for 10 days. Co-administration of increasing doses of flutamide caused a dose-dependent reduction in prostate to body weight ratios and, in the same animals, caused significant alterations in adult male hepatic microsomal BPH and TR activities. These doses of flutamide did not affect the serum testosterone levels. To test the possibility that the action of flutamide on androgen responsive hepatic microsomal drug and steroid metabolism may be similar to that occurring in the prostate, a tissue which contains an androgen receptor, we also studied the effect of flutamide on the binding kinetics of the high affinity hepatic cytosolic [3H]R1881 binding protein in vivo. Scatchard analysis of [3H]R1881 binding data revealed a reduction in the binding capacity of the hepatic cytosolic androgen binding protein in castrated animals treated with a combination of flutamide and testosterone enanthate at doses capable of maximally altering hepatic microsomal drug and steroid metabolism. No alteration in binding affinity occurred in this treatment group. However, a decreased binding affinity was found when flutamide alone was given. The binding kinetics of the hepatic cytosolic androgen binding protein were not altered in the castrated adult male with or without testosterone treatment. When flutamide was injected daily into the intact adult female rat, no effect was observed on either hepatic microsomal BPH or TR activities. Taken together, these data indicate that flutamide reduces hepatic cytosolic R1881 binding in the adult male rat, and this may explain some of the effects of this antiandrogen on testosterone-sensitive hepatic microsomal drug and steroid metabolism.

Effects of photoperiod on androgen-binding protein and sperm fertilizing ability in the hamster

Androgen binding protein (ABP) was detected in both the testis and epididymis of golden hamsters exposed to a long photoperiod (16L:8D). The concentration of ABP in the testis rose from 0.1 pmol/g testis in 2-week-old animals to attain maximum values (3.9 pmol/g testis) at 6-7 weeks, then declined to adult values (1.8 +/- 0.4 pmol/g testis) after 10-11 weeks of age. In contrast, the ABP concentration of the caput epididymidis reached maximum values at 4-7 weeks of age (14 pmol/g tissue) and declined to adult values (4.8 +/- 1.5 pmol/g tissue) by 10-11 weeks of age. ABP content of the corpus epididymidis was maximal (1.0 pmol/g tissue) at 2 weeks of age and thereafter declined to below detectable levels by 10-11 weeks. No ABP could be detected in the cauda epididymidis from animals of any age examined. Hamster ABP analysed by steady-state polyacrylamide gel electrophoresis had a relative mobility (Rf) of 0.33 compared to 0.41 for rabbit ABP. Sucrose gradient analysis of hamster ABP indicated a sedimentation coefficient of about 4 S. The binding of [3H]5 alpha-dihydrotestosterone [( 3H]5 alpha-DHT) to hamster ABP was very rapid with equilibrium occurring within 10 min. The dissociation of [3H]5 alpha-DHT from hamster ABP was also rapid (t1/2 = 2.77 min). Saturation analysis of ABP from mature animals yielded an apparent dissociation constant of 6.4 nM and an ABP concentration of 1.2 +/- 0.2 pmol/mg protein. The binding of [3H]5 alpha-DHT to hamster ABP was inhibited by 5 alpha-DHT greater than testosterone greater than greater than greater than oestradiol greater than cyproterone acetate. Exposure of mature hamsters to a short photoperiod (8L:16D) for 3 weeks resulted in a 42% drop in epididymal ABP levels (10.3 to 4.3 pmol/g tissue). Epididymal ABP further declined so that after 15 weeks in a short photoperiod it was 4% (0.4 pmol/g) of initial values. Accompanying this decrease in epididymal ABP concentrations was a decline in the fertilizing ability of spermatozoa from the distal cauda. When hamsters were transferred from a short to a long photoperiod (16L:8D), epididymal ABP content returned to about 50% of control values within 3 weeks. However, the fertilizing ability of spermatozoa from the cauda epididymidis of these animals did not return to control values after a 9-week exposure to a stimulatory photoperiod.

Effects of ethane dimethane sulphonate (EDS) on seminiferous tubule function in rats

The effects of a single injection of ethane dimethane sulphonate (EDS) on aspects of seminiferous tubule function were assessed over a period of 49 days. Ethane dimethane sulphonate, which is known to cause destruction of Leydig cells, reduced the levels of testosterone in both serum and testicular interstitial fluid for 21 days, after which recovery occurred. The low testosterone levels were associated with elevated serum levels of LH and FSH. Daily sperm production was decreased from 14 to 42 days post-EDS but returned to control levels at 49 days. The production of seminiferous tubule fluid, measured after unilateral efferent duct ligation, decreased significantly at 7 and 14 days but then recovered. The testicular content of androgen binding protein (ABP) was decreased from 14 to 28 days but returned to normal thereafter. These results demonstrate significant effects on seminiferous tubule function, which may be due to the decrease in testosterone or be associated with a direct effect of EDS.

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)

[Identification of receptors in a system of functionally heterogeneous proteins specifically bound to androgens in rat liver cytosol]

The methods of androgen receptor (RA) isolation and identification in rat liver cytosol were studied. It was shown that male rat liver contains a system of specific androgen (A)-binding proteins consisting of at least three main components: RA, delta 4-androstendione (delta 4-A)-binding component and an unusual estrogen-binding protein interacting also with A and the first two components in females. The identity of one of A-binding components to RA was proved by cumulative properties of this component which are similar to those of RA from other tissues. These properties are as follows: 1) high values of apparent association constant, Ka, for 3H-R1881 (2.8 +/- 0.3 X 10(8) M-1) and 3H-5 alpha-dihydrotestosterone (3H-DHT) (5.0 +/- 0.4 X 10(8) M-1); 2) low binding capacity--approximately 10 fmol/mg of protein of nonfractionated cytosol; 3) pronounced specificity of affinity for active A (DHT, R1881, testosterone); 4) large size of the protein molecule (6.5 +/- 0.25 nm); 5) ability to decrease this size to 3.2 +/- 0.08 nm in a high ionic strength buffer; 6) precipitation at low concentrations of ammonium sulfate: 7) strong interaction with heparin-Sepharose. The properties of the delta 4-A-binding component do not coincide with those of RA: it has a low Ka for 3H-delta 4-A (1.15 +/- 0.5 X 10(6) M-1), a high binding capacity (1.22 +/- 0,12 pmol/mg of protein of nonfractionated cytosol) and can bind various delta 4-3-ketosteroids irrespective of the degree and nature of their biological activity. It was concluded that preliminary isolation of rat liver RA on heparin-Sepharose can be used for differential identification and characterization of this protein.

Effect of local heating of the rat testis on the levels in interstitial fluid of a putative paracrine regulator of the Leydig cells and its relationship to changes in Sertoli cell secretory function

Rat testes were exposed to heat (43 degrees C) for 15 or 30 min to induce moderate or severe disruption of spermatogenesis, respectively. Over 3-42 days after treatment, testicular morphology and weight, the serum concentrations of FSH and the concentrations in interstitial fluid of testosterone, androgen-binding protein (ABP) and a factor(s) capable of stimulating Leydig cell testosterone secretion were monitored. Moderate seminiferous tubule damage induced by 15 min heat exposure caused a small decrease (20%) in testicular weight, but did not affect the other measures, other than transiently. In contrast, after exposure of testes to heat for 30 min there was a major and progressive decline in testicular weight throughout the experimental period, reaching 39% of control values by 42 days. In these animals, the serum concentrations of FSH were significantly increased (P less than 0.01) throughout the period of study as also where the serum and interstitial fluid concentrations ABP (P less than 0.05-0.01) and levels of interstitial fluid factor (P less than 0.01). It is concluded that the activity of the interstitial fluid factor(s) can be increased by inducing severe but selective disruption of spermatogenesis, whereas moderate disruption has no effect. Moreover, as ABP secretion into interstitial fluid was increased after severe but not moderate disruption, this suggests that in such animals proportionately more ABP may be secreted via the base of the Sertoli cell. The parallel changes in activity of the interstitial fluid factor(s) and concentrations of ABP in interstitial fluid also provides further circumstantial evidence that these products may have a common (Sertoli cell) origin.

Measurement of a follicle-stimulating hormone-responsive protein of Sertoli cell origin using an enzyme-linked immunoblot assay

Many proteins secreted by Sertoli cell-enriched cultures are maximally stimulated by a combination of FSH and testosterone. Since very few are stimulated primarily by FSH, we thought it pertinent to identify such proteins. Sertoli cell-enriched cultures were prepared from testes of 20-day-old rats and grown in serum-free medium containing insulin, transferrin, and epidermal growth factor and in such medium supplemented with FSH, testosterone, or FSH plus testosterone. Media were fractionated using HPLC, and proteins were identified by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. A protein designated CMB-2, with an apparent mol wt of 22,000, was shown to increase in response to FSH. Antiserum was raised using denatured protein eluted from SDS-polyacrylamide gels as the antigen, and a specific immunoassay using a combination of SDS-polyacrylamide gel electrophoresis and Western blotting was developed. The production of CMB-2 by primary Sertoli cell-enriched cultures was found to increase in a dose-dependent manner in response to FSH (30-1000 ng/ml); secretion was not significantly affected by testosterone (2 X 10(-13) M). An investigation of the tissue distribution of CMB-2 showed that the puberty, CMB-2 is secreted into the rete testis and accumulates in the epididymis in high concentration. We conclude that CMB-2 will be a useful marker to study the action of FSH on the rat testis.

Stimulation of rat Sertoli cell secretory activity in vitro by germ cells and residual bodies

The direct influence of germ cells and residual bodies on Sertoli cell basal and FSH-stimulated secretion of androgen-binding protein (ABP) was studied using Sertoli cells, recovered from 20-day-old rats, cultured alone or cocultured with a crude germ cell preparation from adult rats or with pachytene spermatocytes, round spermatids or populations of residual bodies enriched by centrifugal elutriation. The effect of a rat liver epithelial cell line (LEC) on Sertoli cell function was also tested. Addition of a crude germ cell preparation increased basal and FSH-stimulated ABP secretion. Pachytene spermatocytes and residual bodies adhered to the Sertoli cell monolayer to a much greater extent than did round spermatids. Addition of pachytene spermatocytes markedly enhanced basal and FSH-stimulated ABP secretion over 12 days of culture. Round spermatids and residual bodies stimulated ABP secretion although to a lesser extent than did spermatocytes. Furthermore, the increase of FSH-stimulated ABP levels was not maintained after 4 or 8 days of culture. LEC also enhanced basal and FSH-induced ABP levels but the increase of FSH-induced ABP production was only observed until Day 8 of culture. The influence of LEC on Sertoli cell secretion could be mediated through the production of an extracellular matrix. It is concluded that germ cells, particularly pachytene spermatocytes, can directly stimulate Sertoli cell secretory activity in vitro.

The heterogeneity of rat androgen binding protein (rABP) in the vascular compartment differs from that in the testicular tubular lumen. Further evidence for bidirectional secretion of rABP

Fractionation of testicular extracts and serum on a Concanavalin A-Sepharose column resolved two peaks of immunoreactive rat androgen binding protein. The rat androgen binding protein in the first peak, designated Form I, was present in the void volume; the other, designated Form II rat androgen binding protein, was bound by the column and specifically eluted by alpha-methylmannoside. In the course of studying the heterogeneity of rat androgen binding protein on Concanavalin A-Sepharose, it was observed that the distribution of the two forms of this protein was similar in the fluid obtained by micropuncture from the seminiferous tubule and the rete testis, that is, the ratios of Form I to Form II were 1:1 and 1:1.8, respectively. By contrast, Form I rat androgen binding protein in blood, interstitial fluid, and thoracic duct lymph of adult rats was reduced relative to Form II; the ratios of Form I:Form II in these fluids were 1:4.4, 1:3.1, and 1:4.6, respectively. since previous studies indicated that the reduced amount of Form I relative to Form II observed in the blood of adult rats was not the result of more rapid clearance of Form I, these results suggest that Form I rat androgen binding protein is preferentially secreted into the lumen of the seminiferous tubule rather than into the interstitial fluid and blood. We conclude that Sertoli cells in adult rats may partition rat androgen binding protein between the interstitial and luminal compartments of the testis based on the carbohydrate composition of this protein.

Identification of hormonally responsive proteins in primary Sertoli cell culture medium by anion-exchange high performance liquid chromatography

Twenty day-old rats were used to prepare Sertoli cell-enriched cultures which were grown for 4 days in serum-free medium supplemented with human transferrin, epidermal growth factor, and insulin. Proteins in the medium were first fractionated by anion-exchange HPLC. Forty-five to 50 fractions were collected, and each was examined by electrophoresis in sodium dodecyl sulfate-containing polyacrylamide gels. Using silver nitrate as a stain, more than 30 proteins were routinely identified. Rat androgen binding protein and rat transferrin were measured by immunoassays. When the cultures were supplemented with either testosterone, FSH, or both hormones and the media fractionated by HPLC and sodium dodecyl sulfate-polyacrylamide gel electrophoresis, these proteins could be tentatively categorized as follows: unresponsive to added hormones; responsive primarily to testosterone; responsive primarily to FSH; or responsive to testosterone or FSH but maximally responsive to both hormones. This report provides a method for identifying proteins in Sertoli cell-enriched cultures and has allowed us to show for the first time that many are responsive to hormones. The procedure takes advantage of the large loading capacity of the HPLC column to allow fractionation of liter quantities of medium. The high resolving power of the column permits preparation of fractions which are highly enriched with one or a limited number of proteins. The purification of many of these proteins is now feasible. The approach described is generally applicable for isolation of proteins from media from a variety of cells.

Androgen-binding proteins from human hyperplastic prostate as evaluated by electrophoresis

Until 1972 it was shown that the androgen action in the prostatic tissue was through receptor proteins. In 1975 the synthesis of methyltrienolone (MT) opened a new field in searching receptor proteins. This synthetic androgen discriminates between receptors and other proteins such as TeBG and albumin. The main purpose in this investigation was to obtain the electrophoretic patterns of human prostatic androgen-binding proteins and compare them with those of other tissues from male genital tract (e.g., testes and epididymis), using as a reference the already described pattern in blood serum. The experimentation was carried out with cytosol (105,000 g) and nuclear fractions from the homogenized tissue. Both fractions were incubated with the tritiated steroids and then treated with dextran-coated charcoal. Polyacrylamide gel electrophoresis (PAGE) was then performed at pH 8.3 with acrylamide (T) 7.7%. The prostatic cytosol incubated with 3H-dihydrotestosterone (3H-DHT) revealed radioactive areas with the following average electrophoretic mobilities relative to Bromophenol Blue (Rf): 0.195, 0.285, 0.815, 0.910. When cytosol was incubated with 3H-MT the pattern showed radioactive peaks with Rf 0.280, 0.570, and 0.969. The nuclear fraction bound 3H-DHT in 0.190, 0.455, 0.570, 0.660, and 1.055 and bound 3H-MT in Rf 1.01. We concluded from these results that the electrophoretic patterns in the prostate gland shared some radioactive areas resembling TeBG and albumin, although they present low binding capacity. The other peaks with different electrophoretic mobilities are in the process of further identification.

Histochemical study of R1881-binding protein, prostatic acid phosphatase, prostate-specific antigen, and r-seminoprotein in prostatic cancer

A histochemical study on R1881-binding protein, prostatic acid phosphatase (PAP), prostate-specific antigen (PA) and r-seminoprotein was conducted. These parameters and histologic grades were compared to each other and with the responsiveness to endocrine therapy. A good correlation was found between histologic grade and presence or absence of R1881-binding protein in the tissue. Presence or absence of R1881-binding protein as well as histologic grade correlated well with responsiveness to endocrine therapy. Positive staining patterns of PAP, PA, and r-seminoprotein in the tissues were similar to each other, particularly between PA and r-seminoprotein. However, no correlation was found between the histologic grade and ratios of PAP, PA or r-seminoprotein-positive cells. Nor was any correlation seen between the ratio of these marker-positive cells and responsiveness to endocrine therapy.

Two-dimensional characterization of prostatic acid phosphatase, prostatic specific antigen and prostate binding protein in expressed prostatic fluid

Specimens of pooled prostatic fluid, collected by rectal massage from men under 50 years of age with no apparent prostatic disorders, were subjected to two-dimensional gel electrophoresis to study the composition of its proteins. In a preliminary study, a total of 57 major protein groups were detected. In the present study, we attempted to identify, in the two-dimensional gels, those that are related to prostate-associated proteins, i.e., prostatic acid phosphatase (PAP), prostatic specific antigen (PSA), and prostate binding protein (PBP). Individual proteins were recognized by the procedure of Western Blot using specific antisera with peroxidase-antiperoxidase as the staining reagent. Each protein spot in the two-dimensional gel was expressed, along the abscissa, by its isoelectric point (pI) and, along the ordinate, by the molecular weight (MW). PAP consisted of a train of more than ten protein spots that occupied an area in the gel from pI 7.0, MW 45,000 to pI 6.0, MW 50,000. Four protein spots with a MW of 34,000 and a pI range of 8.2-8.8 were identified as PSA. PBP was observed as having three protein spots that were located at pI 5.6-6.6 with a single MW of 15,000. For PAP and PSA, additional protein spots with lower MWs also stained positively with the specific antisera, suggestive of the presence of degradative products of these proteins. Following the removal of the serum-related proteins by an extensive absorption with anti-human serum antibody by affinity chromatography, the prostatic fluid contained 27 major groups of non-serum proteins. These non-serum proteins in the prostatic fluid included PAP, PSA, PBP, and their related smaller molecular species. These results indicate that the prostatic fluid contains PAP, PSA, PBP and that their presence and the patterns of their distribution in the two-dimensional gels should be considered as the characteristic property of the prostatic secretions.

Hydrophobic interaction chromatography (HIC) for the separation of protein-bound and free steroids. Application to binding protein and receptor assays

Protein-bound steroids can be separated from free steroids using microcolumns of silica gel coated with an hydrophobic (octadecyl) solid phase. The bound fraction is eluted in the assay buffer, whereas the free fraction is retained quantitatively on the column in the first step and can be recovered in methanol. Both fractions can be quantitated directly (e.g. by liquid scintillation spectrometry when using radioactive ligands) or kept for further analysis (e.g. by TLC, HPLC etc.). Separation of the bound and free fractions is rapid, accurate and reproducible; intra- and inter-assay coefficients of variation are lower than 5 and 10%, respectively. Recovery of radioactive steroids is high (usually over 85%) and can be estimated separately for each sample. Since assay blanks are very low (typically less than 0.1% of input), this new method, which could be termed "hydrophobic interaction chromatography" (HIC), should prove especially useful for the development of sensitive binding assays, particularly in the field of steroid receptors. The HIC method compared well with three methods currently used for steroid binding assays, namely adsorption of unbound steroids on dextran-coated charcoal, gel filtration on Sephadex LH-20 and adsorption of steroid-protein complexes on DEAE-cellulose filters. Examples of application described here include studies on human plasma sex hormone binding globulin (SHBG) and SP2 placental protein (saturation analysis, binding specificity etc.), the separation of antibody-bound steroids in a radioimmunoassay and the estimation of androgen binding to rat epididymal androgen binding protein (rABP). Receptor assays are illustrated by saturation analysis of the mouse uterine oestrogen receptor and of the androgen receptor in the human genital skin.

Extracellular matrix regulates Sertoli cell differentiation, testicular cord formation, and germ cell development in vitro

Sertoli cell preparations isolated from 10-day-old rats were cultured on three different substrates: plastic, a matrix deposited by co-culture of Sertoli and peritubular myoid cells, and a reconstituted basement membrane gel from the EHS tumor. When grown on plastic, Sertoli cells formed a squamous monolayer that did not retain contaminating germ cells. Grown on the matrix deposited by Sertoli-myoid cell co-cultures, Sertoli cells were more cuboidal and supported some germ cells but did not allow them to differentiate. After 3 wk however, the Sertoli cells flattened to resemble those grown on plastic. In contrast, the Sertoli cells grown on top of the reconstituted basement membrane formed polarized monolayers virtually identical to Sertoli cells in vivo. They were columnar with an elaborate cytoskeleton. In addition, they had characteristic basally located tight junctions and maintained germ cells for at least 5 wk in the basal aspect of the monolayer. However, germ cells did not differentiate. Total protein, androgen binding protein, transferrin, and type I collagen secretion were markedly greater when Sertoli cells were grown on the extracellular matrices than when they were grown on plastic. When Sertoli cells were cultured within rather than on top of reconstituted basement membrane gels they reorganized into cords. After one week, tight junctional complexes formed between adjacent Sertoli cells, functionally compartmentalizing the cords into central (adluminal) and peripheral (basal) compartments. Germ cells within the cords continued to differentiate. Thus, Sertoli cells cultured on top of extracellular matrix components assume a phenotype and morphology more characteristic of the in vivo, differentiated cells. Growing Sertoli cells within reconstituted basement membrane gels induces a morphogenesis of the cells into cords, which closely resemble the organ from which the cells were dissociated and which provide an environment permissive for germ cell differentiation.

Identification of androgen-binding protein from testis cytosol and sertoli cell culture medium of the cynomolgus monkey, Macaca fascicularis

The biochemical and immunological properties of monkey androgen-binding protein (mABP) from the cynomolgus monkey, Macaca fascicularis, have been examined in testis cytosol and medium of primary Sertoli cell-enriched cultures. mABP in testis tissue was separated from the serum protein testosterone-estradiol-binding globulin (mTeBG) by affinity chromatography on Concanavalin A-Sepharose (Con A). mTeBG from serum extracts was completely retained by the lectin and could be displaced with buffer containing alpha-methyl-D-glucoside. In contrast, mABP from testis extracts either did not interact with the Con A and appeared in the void volume or was partially retained by the column and could be eluted with buffer alone. A third component retained by the Con A may represent mTeBG contamination, a form of mABP which binds to Con A, or both. The specific 5 alpha-dihydrotestosterone (DHT)-binding activity in the void volume of the Con A column was designated mABP and was further studied. [3H]DHT binding to mABP was saturable and of limited capacity (0.163 +/- 19 pmol/mg protein). Scatchard analysis of the data was consistent with a single class of binding sites with an apparent dissociation constant (Kd) at 4 C of 2.6 +/- 0.2 X 10(-9) M. DHT was the most effective competitor of [3H]DHT binding to mABP, followed by 2-methoxyestradiol, testosterone, estradiol, and cyproterone acetate. Concentrated Sertoli cell culture medium subjected to steady state polyacrylamide gel electrophoresis produced a single peak of specifically bound [3H]DHT with a mobility similar to that of other androgen-binding proteins. [35S]Methionine-labeled medium proteins were immunoprecipitated with a rabbit anti-human TeBG antiserum. Two bands, corresponding to mol wt of approximately 46,000 and 48,000, were observed by fluorography, with the lighter component being more intense. After androgen affinity chromatography of radiolabeled medium proteins, these two bands were again observed on sodium dodecyl sulfate-urea-containing polyacrylamide gels. These results demonstrate that 1) mABP may be separated from mTeBG by lectin affinity chromatography, as in humans; 2) hTeBG and mABP are antigenically related; and 3) mABP consists of subunits of different mol wt in unequal ratios.

Evidence that progesterone binding uteroglobin is similar to myosin alkali light chain

Using a computer program designed to detect evolutionary relationships between proteins, I find that exon 2 of rabbit uteroglobin, a progesterone binder, and part of myosin alkali light chain have a comparison score that is 7.2 standard deviations higher than that obtained with a comparison of randomized sequences of these proteins. The probability (p) of getting this score by chance is less than 10(-12). This theoretical finding that these sequences are similar has led to the experimental finding that copper, calcium and the tranquilizer trifluoperazine, a calmodulin binding ligand, affect progesterone binding to uteroglobin.

[Endocrine therapy of prostatic cancer]

Response rate of prostatic cancer to endocrine therapy is approximately 80%, but more than half of responders show relapse by five years. Factors influencing prognosis are histological grade, stage, effect of elevated acid phosphatase, and androphilic protein observed histochemically. Relapse may be attributable to progression and clonal selection.

There are two forms of androgen binding protein in human testes. Comparison of their protomeric variants with serum testosterone-estradiol binding globulin

To determine how the androgen binding protein in human testes (hABP) is related to the serum protein, testosterone-estradiol binding globulin (hTeBG), both proteins were isolated and compared. The hABP in extracts of human testes was composed of two molecular species based on concanavalin A (ConA)-Sepharose chromatography. Form I hABP did not interact with ConA while Form II hABP bound to ConA and eluted with alpha-methylmannoside. Form I and Form II hABP from five batches of testes were then purified approximately 30,500- and 30,000-fold to apparent homogeneity by high-performance liquid chromatography and compared with hTeBG isolated from human pregnancy serum. Fractionation of both forms of hABP and hTeBG by polyacrylamide gel electrophoresis in the absence of sodium dodecyl sulfate suggested that the native forms of these proteins were indistinguishable. However, analysis of the purified proteins on sodium dodecyl sulfate-containing polyacrylamide gels indicated that all three were dimers and that each was composed of monomers of at least two sizes which were not present in equimolar concentrations. Two distinctive monomers or protomers of each protein were designated as heavy (H) and light (L) according to their electrophoretic mobilities on sodium dodecyl sulfate-polyacrylamide gels. The H and L protomers of Form I hABP showed apparent molecular weights of 55,000 and 52,000, respectively, in all preparations and were usually present in a 4:5 ratio (H:L). The two components of Form II hABP had apparent molecular weights of 53,000 and 48,000, respectively, and existed in a ratio of approximately 20:1. These two components could not be distinguished in some preparations where Form II hABP migrated as a broad band rather than as distinct protomers. By contrast, hTeBG, which was similar to Form II hABP with respect to ConA binding, always exhibited discrete H and L protomers in a 10:1 ratio. Photolysis of these highly purified proteins with delta 6-[3H]testosterone resulted in specific covalent labeling of their binding sites, confirming that the products identified by silver staining and immunoblotting were indeed steroid binding proteins. The H and L protomers of Form I hABP and hTeBG were separated and examined by peptide mapping using Staphylococcus aureus protease V8 and chymotrypsin. The comparison of the respective fragmentation patterns of protomers indicated that Form I hABP and hTeBG contained distinctive peptides.(ABSTRACT TRUNCATED AT 400 WORDS)

Changes in intratesticular testosterone, cytoplasmic androgen receptors and ABP content of the ram testis after a single endogenous pulse of LH

The effects of an endogenous LH pulse on the testicular concentration of testosterone, cytoplasmic androgen receptor content and androgen binding protein (ABP) content was studied in rams. Blood was collected from 36 rams for at least 14 h and their testes then removed. Animals were then grouped according to the interval from their last LH pulse and the time of slaughter. The concentration of testosterone in the testis was highest during the first h following the LH pulse and returned to its baseline within 5 h. There was a 60% reduction in the testicular content of cytoplasmic androgen receptors at 3 h after the LH pulse, followed by slow replenishment. The testicular content of ABP was highest at 4 h after the LH pulse. It is in the testis concluded that the pulsatility of LH and testosterone induces a pulsatile translocation of cytoplasmic androgen receptors.

Testicular toxicity of antineoplastic drugs during postnatal development of the rat

A multidisciplinary approach was chosen to assess effects of anticancer drugs on the postnatally developing reproductive system. Male rats were treated once with doxorubicin (3 mg/kg bw i. p.) on either postnatal day 6, 16, 24, or 45. Mating studies, sperm counts, estimation of androgen binding protein and assessment of pathological parameters were performed at the time of onset of reproductive capacity of the controls and for 12 weeks thereafter. Male reproductive toxicity of doxorubicin was clearly dependent on the age at the time of treatment, being greatest for 6 day old animals and absent for 45 day old animals.

Rapid method for quantitation of androgen binding protein in Sertoli cell cultures and its use for measurement of binding kinetics

The accurate measurement of the kinetics of binding of 5 alpha-dihydrotestosterone to the Sertoli cell specific protein, androgen binding protein (ABP), has been frustrated by the extremely rapid rate of dissociation of the ABP-dihydrotestosterone complex. We describe a rapid and highly sensitive assay suitable for ABP quantitation which utilizes DEAE Bio-Gel and [3H]dihydrotestosterone. The assay has been used to accurately measure the rate of dissociation (8.25 X 10(-4) s-1, t1/2 14 min) and the rate of association (2.04 X 10(5) M s-1) of the binding of [3H]dihydrotestosterone to rat ABP. The ratio of these rate constants is in perfect agreement with the equilibrium dissociation constant determined by Scatchard analysis (4.0 nM). This multipoint assay is extremely rapid such that binding can be measured at equilibrium, it has high precision (coefficient of variation 3%), and is particularly useful at low protein concentrations (50 ng/ml); furthermore, the assay background of nonspecific 3H-binding is extremely low (0.2%). Since at such low protein concentrations a 10 point Scatchard analysis can be performed on 1 ml culture medium containing as little as 3 fmol ABP, the assay is suitable for monitoring changes in ABP secretion resulting from manipulations of cells in culture. The assay which utilizes DEAE Bio-Gel A is compared to five alternative methods: the standard method of steady state gel electrophoresis, Dextran-coated charcoal assay, hydroxylapatite assay, DEAE filter assay, and radioimmunoassay. The DEAE Bio-Gel assay has advantages over all of these alternative methods. In summary, this new assay is particularly useful for monitoring temporal changes in the secretion of ABP, and the method is equally effective in quantitating ABP in rat, rabbit and hamster Sertoli cell cultures.

Ultrastructural localization of uteroglobin immunoreactivity in rabbit lung and endometrium, and rat ventral prostate

Recent biochemical studies have demonstrated amino acid sequence homologies between uteroglobin from rabbit endometrium and prostatic binding protein from rat ventral prostate. We have studied the ultrastructural distribution of uteroglobin-immunoreactive material in rabbit lung and endometrium and rat ventral prostate using an uteroglobin antibody raised in guinea pigs. Secretory granules of bronchiolar Clara cells, endometrial non-ciliated cells and rat prostate secretory cells gave a positive immunoreaction when this antibody was used. The results indicate a close relationship of immunoreactive epitopes of proteins present in those secretory cells. The functional properties of these proteins (glycoproteins, steroid binding, androgen-dependent secretion) suggest a close functional relationship, for instance a surface action such as coating, capping, masking or lubrication.