[The method for the measurement of the binding capacity of androgen binding protein in human semen (author's transl)]

In the present study, the androgen-binding properties of human semen was evaluated by experimenting with incubation and the technique for separating bound from unbound hormones. Some of the properties of a protein in human seminal plasma (SPABP) that has a high affinity and low capacity for binding dihydrotestosterone (DHT) was found and studied. The dissociation constant (Kd) was 1.63 X 10(-9) M and the number of binding sites of 275.3 X 10(-12)M was obtained. The intraassay and interassay coefficient of variation of this assay method was less than 5.6% and 8.4%, respectively. DHT was displaced from the binding protein by testosterone (81%), estradiol (75%) and levonorgestrel (63%). The endogenous level of steroids in human seminal plasma did not interfere with the estimation of DHT binding sites. In order to investigate the binding of DHT to human spermatozoa, the separation of sperm from the incubation mixture was accomplished by low-field centrifugation followed by 3,000 X G for 10 minutes. Using this separation method, the optimal steady-state condition for DHT-binding was found to be an incubation time of one hour. The binding of DHT to spermatozoa was nonspecific in nature, that is, of high capacity and low affinity (Kd greater than 10(-6)M).

Membrane-associated steroid-binding proteins of Pseudomonas testosteroni

Previous studies have established the presence of periplasmic steroid-binding proteins in induced Pseudomonas testosteroni. This study reports the presence of two additional steroid-binding proteins which can be released from the cytoplasmic membrane during preparation of membrane vesicles. These two proteins differ from each other and from the periplasmic protein in some of their characteristics and steroid specificity, and appear to be distinct from the two membrane-bound steroid dehydrogenases, 3 beta and 17 beta-hydroxysteroid dehydrogenase and 1-ene-dehydrogenase.

[Studies of androgen binding protein. 1st report: Androgen binding protein in testis and epididymis of rabbit and human (author's transl)]

Androgen-binding protein (ABP) appears to originate in the Sertoli cells, which are stimulated by FSH and androgens, and serves to transport androgen into the lumen of the seminiferous tubules. Androgen may be more readily available for the process of spermatogenesis and sperm maturation. ABP was measured in rabbit and human testes using the method of polyacrylamide gel electrophoresis described by Ritzen et al. (1974). The values of ABP were as follows: rabbit testes (n=6) 0.44 +/- 0.05 pmoles/mg protein, rabbit caput epididymides (n=5) 5.52 +/- 1.4 pmoles/mg protein, rabbit corpus epididymides (n=5) 1.35 +/- 0.43 pmoles/mg protein, rabbit cauda epididymides (n=5) 0.39 +/- 0.12 pmoles/mg protein, rabbit efferent duct fluid (n=2) 62.4 +/- 24.6 pmoles/mg protein and human testes (obtained from untreated patients with prostatic cancer)(n=3) 0.30 +/- 0.22 pmoles/mg protein. Since we could not distinguish ABP from testosterone-estrogen binding globulin (TeBG) with the assay, the values were corrected at first by Hb concentration, but it was not satisfactory, and other methods are now being studied.

Evidence for the existence of an androgen binding protein in hydatidiform mole vesicles

Extracts of hydatidiform mole vesicles and the fluid contained in these vesicles were shown to contain a trophoblastic androgen binding protein. This protein was found to be distinct from serum testosterone-estradiol binding globulin (TEBG) by its isoelectric point, its affinity for dihydrotestosterone (DHT) and by Concanavalin A binding. The elution pH of this binding protein was shown to be 4.6, whereas that of TEBG was pH 5.2-5.3. The apparent dissociation constant (Kd app) for TEBG as determined by Scatchard analysis was 2.0 X 10(-9) M, whereas the Kd app for the trophoblastic binding protein after isoelectric focusing was 1.5 X 10(-10) M. A second binding protein found in both vesicular extracts and mole fluid was shown to have an isoelectric elution value (pH 5.2) similar to TEBG and an Kd app of 1.7 X 10(-9) M DHT, very close to the TEBG value. Apparent equilibration for both proteins with DHT was shown to occur in approximately 4H, and both proteins were shown to be high affinity, low capacity binders. The relative affinities of both proteins for other steroids was found to be similar except for methyltrienolone, which appeared to have a higher affinity for the trophoblastic binding protein.

Recovery of testicular functions after surgical treatment of experimental cryptorchidism in the rat

When rats were made unilaterally cryptorchid at 17 days of age (before spontaneous descensus), the further maturation of the testis was prevented. At 34 days of age, the abdominal testis was smaller than the scrotal testis and showed less secretion of the Sertoli cell specific androgen binding protein (ABP). In 120-130 days old rats that were made bilaterally cryptorchid at 17 days of age, testicular weight, histology, secretion of fluid and ABP were restored and testosterone secretion and fertility were normal if orchidopexy was performed at 33 days of age. If the orchidopexy was delayed until 59 days of age, the recovery of testicular function and morphology was only partial. The results show that in the rat, the testicular damage caused by cryptorchidism is reversible, if the abdominal testis is surgically descended during early sexual maturation.

Histochemical observation of F 1881 binding protein in human benign prostatic hypertrophy

A 3-carboxymethyloxime conjugate of R 1881 was conjugated with bovine serum albumin and reacted with fluorescein isothiocyanate. Tissue sections from patients with benign prostatic hypertrophy were incubated with this compound. Fluorescence was observed in the cytoplasm of gland cells, although both positive and negative cells were distributed evenly in some areas. Neither the stroma nor the nuclei of epithelial cells were fluorescent. Preincubation with a 20 fold molar excess of R 1881-carboxymethyloxime-bovine serum albumin, 1 microM of R 1881, or 1 microM of triamcinolone acetonide diminished fluorescence of the section. Bovine serum albumin conjugated with fluorescein isothiocyanate did not stain the section. Therefore, the fluorescence observed in the sections seems to be attributable to the high affinity binding of R 1881. The intensity and number of fluorescent cells and the R 1881 binding estimated by a biochemical method were well correlated.

The effect of vasectomy on Sertoli cell function in rats

In order to evaluate Sertoli cell function after vasectomy, we studied a group of 24 rats. Twelve animals underwent bilateral vasectomy and 12 control animals underwent a sham operation. At 3 and 8 weeks postvasectomy, six experimental and six control animals were sacrificed. Forty-eight hours before sacrifice, the efferent ducts of the testes of each animal were ligated to produce intratesticular androgen-binding protein (ABP) accumulation. Quantification of ABP was determined using a steady-state polyacrylamide gel electrophoresis system and a 2 nM 3H-dihydrotestosterone label. The ABP of the vasectomized and control animals was expressed as both picomoles per milligram of protein and picomoles per organ and was found to be 0.28 +/- 0.06 and 0.42 +/- 0.09 for the control and vasectomized animals at 3 weeks and 0.46 +/- 0.07 and 0.52 +/- 0.08 for similar groups at 8 weeks. Comparison of these values revealed no statistical significance. Vasectomy, therefore, had no demonstrable effect on Sertoli cell function in the rat and our findings support the concept that ligation of the vas does not result in long-term biochemical testicular damage in the experimental animal.

Androphilic proteins in the human prostate

Dihydrotestosterone-binding protein in cytosols from human prostates was different from the R1881- and R5020-binding proteins. The R1881- and R5020-binding proteins in the cytosol were very similar and most of the binding sites for R1881 were capable of binding R5020. However, nuclear extracts showed equal binding to dihydrotestosterone and R1881, but not to R5020, suggesting that there might not be a progestin receptor in the human prostate. Maximum binding sites to dihydrotestosterone, R1881, and R5020 in cytosols were very similar among "normal" and pathological prostates except that dihydrotestosterone binding was higher in "normal" prostates than in the pathological ones. Histochemically, R1881-binding was observed in the epithelial cells and in malignant cells, but not in the stroma.

Preliminary characterization of a new androgen-binding protein in human seminal plasma

In order to obtain comparative analysis between the steroid binding proteins from blood serum and seminal plasma, fresh samples were incubated and assayed in parallel with the following tritiated steroids: dihydrotestosterone, testosterone, cortisol, progesterone and estradiol. Thereafter, and using techniques such as (1) polyacrilamide disk gel electrophoresis with elution of proteins from the gel slices, (2) ammonium sulphate precipitation, (3) enzymatic hydrolysis, and (4) gel filtration on Sephadex G-100, there was a resemblance in the electrophoretic patterns confirming the presence in both fluids of proteins like TeBG, CBG, and Albumin, previously described in blood serum. In seminal fluid, but not in blood serum, another small protein with androgen binding capacity was found and its preliminary characterization demonstrated: disappearance with enzymatic treatment, low molecular weight, negative charge, and precipitation range with ammonium sulphate from 30 to 35%. Its elution profile on Sephadex G-100 was contaminated with albumin.

Biochemical and physiological studies of androgen-binding protein in the reproductive tract of the ram

The electrophoretic mobility, effect of pronase, temperature stability, affinity constant and specificity of androgen-binding protein (ABP) were compared in rete testis fluid (RTF), cauda epididymal plasma (CEP) and seminal plasma (SP) of the ram in which the levels of ABP, dihydrotestosterone (DHT), total protein and the number of spermatozoa were also measured. The characteristics of the ABP appeared to be almost identical in all 3 fluids. ABP was highly concentrated in the cauda epididymidis although 50-75% of it was utilized or destroyed during transit through the epididymis. The levels of ABP were higher in the breeding season and positively correlated with DHT in RTF and SP. It is concluded that ABP might be responsible for the increase in DHT in the reproductive tract of the ram during the breeding season and that ABP in the SP might serve as a useful marker of Sertoli cell function in the ram.