Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P56851 (epididymal)
 11,273 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Assays of androgen-binding protein (ABP) were carried out on testes, and epididymal heads and tails. This strain of rat exhibits a heritable mutation physically manifested as unilateral or bilateral maldescended (ectopic) testes. When present, they are found immediately cranial to the external inguinal ring in the superficial connective tissue on the ventral body wall. Charcoal-extracted cytosols were preincubated with 16 nM tritiated 5 alpha-dihydrotestosterone ( [3H] DHT) for 16-20 h at 4 degrees C and ABP was separated by polyacrylamide gel electrophoresis under steady-state conditions in the presence of 2 nM [3H] DHT. The gels were transversely cut into 2.1-mm thick slices and serially counted in a liquid scintillation counter. Binding of [3H] DHT to ABP was assumed to be 1:1 and the sum dpm of the ABP-containing slices corrected for background was expressed as pmol DHT bound/mg protein. Compared to normal male siblings, cytosol ABP levels on the ectopic side in unilateral ectopic rats were 78% and 93% lower than normal in epididymal heads and tails, respectively; whereas similar values for either side in bilateral ectopic rats were 88% and 99%. The above differences indicated in the cytosol ABP levels were significant at P less than 0.0001. On the other hand, in no case were differences in ABP levels in normal and ectopic testes in bilateral ectopic, unilateral ectopic and normal male rats significant. Also, epididymal heads and tails on the descended side of unilateral ectopic rats demonstrated no significant difference when compared to corresponding tissues in normal male siblings.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Ectopic testes: a heritable mutation in the King-Holtzman rat: androgen-binding protein in testes and epididymides. 614 35

The ability of spermatozoa recovered from the successive segments of the hamster epididymis to bind to the zona pellucida was studied and a major increase was found as spermatozoa passed from the proximal to the distal portion of the corpus epididymidis (1.95 compared with 20 spermatozoa bound/egg). Tubules from the proximal epididymis were cultured in conditions which preserved the motility of the contained spermatozoa for 48-72 h. Addition of 2 microM-5 alpha-DHT to the culture medium for 17 h stimulated the incorporation of 3H-labelled amino acids into several protein bands whose mobility in polyacrylamide gel electrophoresis was coincident with those of glycoproteins EP1-EP6, previously identified as androgen-dependent in the hamster epididymis in vivo. Examination of the material extracted from washed spermatozoa with 0.5 M-NaCl revealed the presence of radioactive proteins on spermatozoa. The zona-binding ability of spermatozoa from androgen-treated cultured proximal corpus tubules was significantly increased (P less than 0.001) as was the no. of spermatozoa/egg (5.51) compared with the value for control cultures (0.87 spermatozoa/egg). We suggest that androgen-dependent epididymal secretory proteins that associate with spermatozoa might participate in the formation or activation of a site for zona pellucida recognition in the sperm surface.
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PMID:Addition of androgens to cultured hamster epididymis increases zona recognition by immature spermatozoa. 623 Apr 44

We examined the influences of steroids present in the epididymis on androgen metabolism by epididymal tissue and on the binding of androgen metabolites to the epididymal androgen receptor in castrated adult rabbit epididymides under in vitro conditions. The conversion of [3H]testosterone to [3H]17 beta-hydroxy-5 alpha-androstan-3-one (5 alpha-DHT) and to [3H]5 alpha-androstane-3 alpha (beta), 17 beta-diol was inhibited by unlabeled steroids in the following manner progesterone greater than testosterone greater than estradiol. Unlabeled 5 alpha-DHT did not inhibit [3H]testosterone metabolism indicating that product inhibition is not an important regulatory event. The antiandrogen cyproterone acetate did not inhibit the formation of 5 alpha-reduced metabolites of [3H]testosterone. All of the compounds used inhibited androgen binding to the classically defined cytoplasmic and nuclear androgen receptor.
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PMID:The effects of various steroids on testosterone metabolism by the sexually mature rabbit epididymis. 654 32

The increase in zona pellucida binding caused by the exposure of cultured proximal corpus epididymidis to 2 microM-5 alpha-DHT (0.87 and 4.29 spermatozoa/egg for control and 5 alpha-DHT group respectively) was lost when 20 microM-cycloheximide was also added to the medium (0.72 spermatozoa/egg). These results were interpreted as meaning that de-novo protein synthesis was required to obtain the effect of androgens. When a fraction enriched in epididymal glycoproteins EP2-EP6 (18% total protein in epididymal cytosol and 30% in enriched fraction) and depleted of androgens (less than 120 pg testosterone + DHT/ml) was added to the cultured epididymal tubules, the zona pellucida-binding ability of the contained spermatozoa increased from 0.55 in controls to 2.73 spermatozoa/egg in the extract-treated group (P less than 0.02). When the enriched fraction was prepared from epididymides of 30-day castrates, the stimulatory effect was lost (1.04 spermatozoa/egg). We suggest that proteins synthesized in the epididymis are required to obtain the effect of androgens and that the glycoproteins EP2-EP6 may be involved.
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PMID:Epididymal proteins mimic the androgenic effect on zona pellucida recognition by immature hamster spermatozoa. 674 51

A study was made of unoccupied androgen binding sites in the nuclei of ventral prostate glands of male rats. They were measured at 0 degrees C by comparing specific binding of 1 nM [3H]DHT to salt extract of purified nuclei during the first hour with specific binding during both hours. This method was dependent upon demonstrated completion of uptake into unoccupied binding sites within the first hour and linearity of exchange with occupied binding sites during both hours. Unoccupied binding sites were not artefactual. They did not increase if tissue concentration was diluted prior to homogenization, while they decreased if homogenization was delayed after the tissue was minced. They could be occupied, both in vitro (if precharged with at least 1 nM unlabeled DHT) or in vivo, by administering testosterone propionate subcutaneously or by infusing testosterone into the jugular vein. Exposure to a high concentration of unoccupied prostatic cytosolic binding sites (608.4 fmol from castrated rats) as compared to low concentration (29.3 fmol from intact rats) during homogenization had little effect upon nuclear unoccupied binding site concentrations (2.16 fmol/mg DNA vs 2.41 fmol/mg DNA, respectively). In individual rats, concentration of unoccupied nuclear androgen binding sites was 4.61 +/- 1.05 fmol/mg DNA, while total binding site concentration (measured with 10 nM [3H]DHT for 24h at 12 degrees C) was 866 +/- 103 fmol/mg DNA. Unoccupied nuclear binding sites reached their highest concentration in animals 4 months old (15.09 fmol/mg DNA) when animals 21 days through 720 days of age were studied. By use of association and dissociation rates of binding, it was determined that the apparent Kd of nuclear binding sites was 1.11 X 10(-12) M. There were no observed differences between unoccupied and occupied binding sites in steroid specificity or in sedimentation rate in an 8-24% glycerol density gradient. Although no physiological importance can be attributed as yet to unoccupied nuclear androgen binding sites in the prostate, they do provide a convenient comparison with putative androgen binding sites in the nuclei of testicular and epididymal germ cells.
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PMID:Nuclear androgen binding sites in the male rat. I. Unoccupied sites in the prostate. 674 44

ABP is a protein found in the testicular cytosol or secreted by Sertoli cells in the rete testis fluid. It has a high affinity for androgers and binds specifically 5 alpha-DHT and testosterone (but to a lesser extent). The binding capacity is saturable. ABP is measured by steady state polyacrylamide gel electrophoresis or by separation on dextran coated charcoal. ABP moves from testis to epididymis where its binding activity is totally or partially destroyed from caput to cauda epididymis. In some species (ram, bull, billy goat) but not in others (human, boar, stallion) ABP is present in the seminal plasma of the ejaculate. In some species like the rat, ABP is also secreted in the testicular blood stream by Sertoli cells through the basement membrane of the seminiferous tubules. ABP varies with age and with season. Its production is under separate endocrine control of FSH and testosterone and its transport from testis to epididymis is specifically controlled by FSH. Through its binding activity, ABP may play a role in spermatogenesis and epididymal sperm maturation by enhancing the local concentration of androgens around the germinal cells and the male gametes. However ABP is not present in some species, like the pig, although their spermatogenesis and epididymal sperm maturation are normal.
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PMID:[ABP: the testicular protein that binds androgens]. 681 32

Androgen-binding protein (ABP) is present in the guinea-pig testis, epididymis and epididymal fluid. Guinea-pig ABP sediments as an approx. 4.6S species on sucrose gradients containing 0.01 M KCl. Electrophoresis on non-denaturing polyacrylamide gels indicated that specific androgen binding was present in epididymal cytosol, but not in plasma. Time-course studies indicated that binding equilibrium is approached in about 2.5 h; the dissociation half-time of [3H]5 alpha-DHT from guinea-pig ABP is 5.64 +/- 0.62 h (n = 6) at 4 degrees C. The relative affinities of some steroids for guinea-pig ABP in relation to 5 alpha-DHT = 1 are: testosterone = 0.55 +/- 0.13 (n = 4), estradiol = 0.14 +/- 0.03 (n = 4), the anti-androgen cyproterone acetate = 0.0025 +/- 0.0002 (n = 3). Guinea-pig ABP exhibited an equilibrium dissociation constant of 6.34 +/- 0.52 nM (n = 3) at 4 degrees C and there were 3.43 +/- 0.78 (n = 3) pmoles of binding sites per mg of protein when homogenates of the whole epididymis were assayed. The concentration of ABP was lowest in the caput-corpus region of the epididymis, highest in the proximal cauda, and intermediate in the distal cauda. Essentially all of the ABP present in the distal cauda was intraluminal, as evidenced by the fact that flushing of the duct eliminated most of the [3H]5 alpha-DHT binding activity.
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PMID:The presence of androgen-binding protein in the guinea-pig testis, epididymis and epididymal fluid. 689 45

The effect of age on in vivo tritiated testosterone (3H-T) metabolism and on epididymal 5 alpha-reductase and 3 alpha/beta-hydroxysteroid dehydrogenase activity has been studied on male Wistar rats. Following i.m. injection of 3H-T to 3 and 25 month old functionally hepatectomized rats, the accumulation of 5 alpha-androstan-17 beta-ol-3-one (DHT) by both the caput and cauda epididymidis, prostate, and seminal vesicles was significantly higher in the younger animals than in the old. The total conversion of 3H-T by both epididymal segments was unaltered with advancing age whereas a significant decrease was observed in both prostate and seminal vesicles. The ratio between 17 beta-hydroxy and 17-keto metabolites in the prostate and epididymis of both hepatectomized and intact animals decreased significantly with age. The ratio values for the seminal vesicles showed no significant age variation. The formation of total 5 alpha-reduced metabolites by epididymal homogenates showed a linear decrease with advancing age. The activity of 5 alpha-reductase fell from 16.1 to 10.3 ng/mg protein/30 min. 3 alpha/beta-hydroxysteroid dehydrogenase activity was unaffected by age. The reduced levels of active testosterone metabolites reported with old age are a result of a decrease in 5 alpha-reductase activity, the ultimate cause of which is most probably an age associated defect in the hypothalamic-pituitary-testicular feedback system.
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PMID:Androgen metabolism by rat epididymis. 8 Age dependent changes in androgen metabolizing enzymes in rat accessory sex organs. 694 45

Androgen-binding protein (ABP) in rat epididymal cytosol and sex hormone-binding globulin (SHBG) in rabbit serum and SHBG purified from human serum were active-site-directed photoaffinity radiolabeled with 17 alpha-[(E)-2-[125I]iodoethenyl]androstan-4,6-dien-17 beta-ol-3-one ([125I]1). The interaction of this compound with binding components in epididymal cytosol was dependent on exposure of the mixture to ultraviolet light and on the duration of exposure. Photolysis in the presence of [125I]1 and 5 alpha-dihydrotestosterone (5 alpha-DHT) resulted in a 40% inhibition of binding of [125I]1 to cytosolic components. These result indicate that, while [125I]1 interacted with 5 alpha-DHT binding sites, it also formed adducts with other sites. To characterize the labeled species, the photolysis mixture was subjected to electrophoresis under denaturing and reducing conditions. Autoradiography of the gel revealed that ABP and SHBG were labeled with [125I]1, but in cytosol and serum, higher and lower molecular weight components were also labeled. Purified SHBG was labeled, but no labeled contaminating protein was detected. The presence of 5 alpha-DHT completely inhibited [125I]1 photolabeling of human and rabbit SHBG and of ABP. However, in cytosol, the presence of 5 alpha-DHT also eliminated photolabeling to a component that may be albumin, but 5 alpha-DHT did not affect [125I]1 photolabeling of other contaminating proteins in cytosol. Thus, while [125I]1 is an effective photoaffinity radiolabel for ABP and SHBG, the observation that it also photolabels other proteins limits its practical use to the radiolabeling of purified ABP and SHBG preparations.
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PMID:Active-site-directed photoaffinity radioiodination of androgen-binding proteins. 779 27

The objective of this investigation was to evaluate histologically and pathologically the effect of long-term sustained release of D and DHT on the reproductive system of male rats. A total of 120 Sprague-Dawley male albino rats were distributed equally into three groups. Two CDD, one nonimpregnated and the other impregnated with PLA, were implanted in each rat in groups I and II. Capsules implanted in group I rats were loaded with 20 mg DHT and 20 mg D each. Group II rats were implanted with two empty capsules (sham group), and group III animals served as unimplanted controls. Blood samples were withdrawn weekly via tail artery from all animals. Eight rats from each group were euthanized at the end of the one, three, six, nine, and twelve months following the implantation of the devices. No significant changes in the weights of vital (spleen, kidneys, heart, adrenals, lungs) organs of rats were observed among any of the three different groups. Vas deferens and epididymal fluid were devoid of normal spermatozoa within three months of implanting the D+DHT containing devices. Testes weights decreased significantly in the rats implanted with CDD containing D+DHT and the seminiferous tubules became oligospermic after one month and azoospermic after three months.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Pathophysiological evaluation associated with sustained delivery of danazol and dihydrotestosterone in adult male rodents. 794 36


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