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Query: UNIPROT:P56851 (epididymal)
 11,273 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The development of knowledge in four areas of research in male reproductive physiology of particular interest is reviewed. The concept of the blood-testis barrier (BTB), which arose following dye exclusion from the seminiferous tubules, has now been established as the differential transfer from interstitial fluid to tubular and rete testis fluids of molecules of physiological importance. The composition of fluid collected mostly from the rete testis of several species, not only reflects the nature of the barrier, but also the secretory capacity of the Sertoli cell. The functional significance of the transfer of molecules into testicular fluid and the composition of the fluid flowing into the epididymis are discussed. Sertoli cells establish the structural basis of the BTB during puberty and divide the seminiferous epitheliuym into basal and adluminal compartments. The Sertoli cell is the prime target for follicle stimulating hormone (FSH). The responses evoked by FSH are discussed, including special mention of androgen binding protein (ABP) and the protein hormone, 'inhibin', with FSH-suppressing properties. The control of FSH in the lamb is mentioned including new evidence to support a tubular source of a feedback agent with significance during the impuberal stage. Finally, some of the biochemical properties of the epididymis and its fluid contents are reviewed and the epididymal sperm are identified as the site of the antifertility action of the 6-chloro-6-deoxy sugars.
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PMID:Functional relationships of the mammalian testis and epididymis. 677 25

The regional histology and esterase activity of the mouse epididymis after 24, 48, and 72 hr castration is reported. Differential sensitivity to androgen deprivation among the various epithelial cell types is described, allowing of positive identification of the cell types previously observed to survive long-term castration. The possibility of an androgen binding protein, as described in the rat and rabbit, is suggested on morphological grounds. The epididymal body appears to contain a class of highly androgen sensitive cells that degenerate rapidly following castration and a second class that survive from which regeneration occurs on testosterone replacement.
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PMID:Histochemical studies on genetical control of hormonal enzyme inducibility in the mouse. VI. Effects of short term castration. 684 5

The relative binding affinities of testosterone (T), 19-nortestosterone (N) and their 5 alpha-reduced derivatives: 5 alpha-dihydrotestosterone (DHT) and 5 alpha-dihydro-19-nortestosterone (DHN) to the androgen receptor of the rat seminal vesicle was studied using competition experiments. In cell-free extracts incubated at +10 degrees C for 18 h the relative binding affinities of these steroids (DHT greater than T = DHN = N) proved to be specific for the androgen receptor, in the sense that only prostatic extracts gave a similar result while three other androgen binding proteins (human sex steroid binding globulin, rat epididymal androgen binding protein and an antibody raised against T) exhibited quite different binding specificities. In minced seminal vesicles incubated at 37 degrees C for 1 h the binding affinities showed marked differences (DHT greater than N greater than T greater than or equal to DHN) and similar patterns were observed with both the cytoplasmic and the nu clear receptors. Our findings suggest that (I) the simultaneous presence of a 4-ene double bond and 19-methyl group in T does not favor the tight binding of T to the androgen receptor; therefore, either saturation of this double bond or elimination of the 19-methyl group leads to increased binding and (II) while 5 alpha-reduction of T increases the affinity of this steroid to the receptor, that of N does not influence or rather tends to decrease the binding affinity. The opposite changes observed in the binding affinities of T and N after their 5 alpha-reduction may account for the lower androgenicity of N. On the other hand, the relative myotropic activity in vivo of these steroids is apparently determined by the ratio of their affinities (N/T approximately 3 at 37 degrees C) to the androgen receptor.
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PMID:Relative binding affinities of testosterone, 19-nortestosterone and their 5 alpha-reduced derivatives to the androgen receptor and to other androgen-binding proteins: a suggested role of 5 alpha-reductive steroid metabolism in the dissociation of "myotropic" and "androgenic" activities of 19-nortestosterone. 689 Oct 12

The equilibrium affinity constant for rat prostate androgen receptor and epididymal androgen binding protein (ABP) has been determined for thirty-four potential progestogens. Three A-nor-, four A,19-dinor-, and one A-homo-5 alpha-androstane derivative bind to the androgen receptor (KD less than 0.5 muM). Five of these compounds also bind to ABP with an affinity of the same order of magnitude. "Anordrin" (compound 24) and "Dinordrins" (compounds 10, 14, 15, 16, 17), which are potential female contraceptives, do not bind with high affinity to the androgen receptor or to ABP. The following modifications in A-nor derivatives favour binding to the receptor as compared to ABP: 19-nor substitution (compound 1), C-18 methyl homologation (compound 5), 2 alpha-ethinylation (compound 22). One 2 alpha-allenyl A-nor derivative (compound 25) and one A-homo derivative (compound 34) bind almost exclusively to ABP. The interaction with either binding protein is decreased by oxidation or esterification of the hydroxyl group at C-17, and by addition of a 17 alpha-ethinyl group. The latter modifications are likely to increase the specificity of androstane derivatives for receptors other than androgen binding proteins, such as the progesterone receptor.
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PMID:Interaction of A-nor, A, 19-dinor, and A-homo-5 alpha-androstane derivatives with the androgen receptor and the epididymal androgen-binding protein. 689 53

A method for the purification of androgen binding protein (ABP) from the rabbit epididymis is presented. Epididymal extracts were submitted to sequential ammonium sulfate precipitation, androgen affinity chromatography, concanavalin A (Con A) affinity chromatography, and preparative polyacrylamide gel electrophoresis. Since the blood protein testosterone-estradiol binding globulin (TeBG) was a possible component of the epididymal extract, ABP was differentiated and separated from TeBG by affinity chromatography on Con A-Sepharose since the latter protein was shown to be completely absorbed by the lectin while the former was not. The final product was shown to be pure by polyacrylamide gel electrophoresis. Electrophoresis in the presence of sodium dodecyl sulfate revealed that ABP is comprised of subunits.
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PMID:Purification and characterization of androgen binding protein from rabbit epididymis. 720 23

Proluminal movement of 3H-testosterone from peritubular space to intratubular fluids of the adult rat testis and epididymis was studied by using in vivo microperfusion and subsequent micropuncture of seminiferous tubules and caput epididymal tubules. Tubules were perifused with Minimum Essential Medium containing 3H-testosterone. To determine if androgen transport is saturable, 40, 80, 160, and 320 microCi 3H-testosterone were included in the perfusion fluid. Radioactivity of 3H-androgens in the intraluminal fluids was determined at 1 hour after perfusion. Transepithelial 3H-androgen movement in the testis was linear (r = 0.735, p < 0.001, y = 0.17 x +5.6). The movement of 3H-androgen across the epididymal epithelium was saturable (Vmax of 326.5 nM/hr and Km of 77 nM). To determine the effect of estradiol on proluminal androgen movement, estradiol at 10X the cocentration of 3H-testosterone was incorporated in the perifusion fluid. Proluminal 3H-androgen movement into the seminiferous and epididymal tubules was not affected by addition of estradiol to the perifusion fluid. These findings support our previous observations that proluminal transepithelial movement of 3H-androgens could be mediated by its binding to a specific intraluminal androgen binding protein.
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PMID:Transepithelial movement of 3H-androgen in rat seminiferous and caput epididymal tubules: saturability and effect of competition with estradiol. 789 56

1. An androgen binding protein(s) has been partially purified from cell plasma membranes of dog epididymides. 2. The protein(s) has a pI of 5.3 and an association constant of (1.13 x 10(9) M-1). 3. Conclusive demonstration of androgen receptors in epididymal plasma membranes would be of significance in understanding epididymal physiology.
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PMID:Partial purification of a putative membrane bound androgen binding protein in the dog cauda epididymis. 801 44

The target cell(s) of theobromine toxicity on rat testes and reproductive toxicity induced by pure theobromine and cocoa extract are evaluated in the present studies. Theobromine (500 mg/kg x 7 days) inhibited body weight gain in treated rats. Decreased cauda epididymal sperm reserve (38%), seminiferous tubule fluid (STF) volume (33%), lactate concentration in STF (22%), inhibition of binding activity of androgen binding protein (ABP, 21%) and reduced ABP content in STF were also observed in theobromine-treated animals. Cocoa extract containing an equivalent amount of theobromine did not produce significant toxicity in treated rats. Theobromine concentrations in serum and testes from pure theobromine-treated rats were 1.8- and 1.6-fold higher, respectively, than that in rats treated with cocoa extract. The results support Sertoli cells as the primary target cells of theobromine toxicity. The lower theobromine concentrations in serum and testes of cocoa extract-treated rats could account for the lower toxicity in these animals.
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PMID:Theobromine toxicity on Sertoli cells and comparison with cocoa extract in male rats. 829 20

The free fatty acid (FFA) concentration in the epididymal cytosol of the adult rat was found to be 20-fold higher than in the serum. The binding of [3H] dihydrotestosterone to epididymal rat androgen binding protein (rABP) was modified by physiological concentrations of saturated and unsaturated fatty acids. Polyunsaturated fatty acids inhibited the binding more efficiently than monounsaturated or saturated fatty acids. Scatchard analysis and Dixon plots indicated that the number of binding sites decreased in presence of unsaturated fatty acids with an inhibition constant (Ki) of 4 microM for arachidonic acid (C20:4) and 20 microM for oleic acid (C18:1). These results indicate that unsaturated fatty acids induce alterations in rABP steroid-binding properties that could modulate the endocrine function of rABP.
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PMID:Free fatty acid-induced alterations in the steroid-binding properties of rat androgen-binding protein. 842 2

It is well established that congenital hypothyroidism leads to male infertility. However, there is a dearth of information on foetal-onset hypothyroidism-induced changes in the epididymis. With regard to transient hypothyroidism, the existing literature deals mainly with the testis. However, it is not known whether there is any corresponding alteration in epididymal morphology and physiology under such a condition. The present study is therefore aimed at understanding the impact of persistent and transient hypothyroidism on the concentration of epididymal sex steroids, as they play a vital role in maintaining the normal structure and function of the epididymis. Normal rats of 90 days of age served as controls (Group I). Hypothyroidism was induced by using pregnant/lactating mothers and post-weaning rats to 0.05% (w/v) methimazole (MMI) in the drinking water. Group II were subjected to persistent hypothyroidism from day 9 of post-coitum (pc) to 90 days. Group III rats were subjected to transient hypothyroidism from day 9 day pc to day 1 post-partum (pp), 21 pp or 35 pp (IIIa, b and c, respectively) and group IV rats were given simultaneous T3 supplementation (3 microg/100 g body wt./day i.m.) with MMI from day 9 pc to day 1 pp; 21 pp and 35 pp (Group IVa, b and c). Animals from all groups were killed on day 90 pp. Serum thyroid stimulating hormone (TSH) and thyroid hormones confirmed euthyroidism in group I, IIIa, b and c and IVa, b and c rats and hypothyroidism in group II rats. Caput and cauda epididymal concentration of testosterone, dihydrotestosterone (DHT), estradiol (E2) and androgen binding protein (ABP) markedly decreased in group II rats. While the concentration of testosterone, E2 and ABP increased in group III rats, that of DHT remained unaltered. However, group IV rats maintained normal concentration of the sex steroid and ABP. The activity of 5-alpha-reductase in the epididymis of all the groups followed the same trend as that of the concentration of epididymal DHT. From the present data it is evident that persistent hypothyroidism diminishes the bioavailability of androgens and oestrogens, while transient hypothyroidism enhances the same, indicating the importance of euthyroidism during foetal and neonatal period towards the maintenance of optimal hormonal status in the epididymis required for its maturation.
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PMID:Impact of foetal-onset hypothyroidism on the epididymis of mature rats. 1203 Oct 41


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