UNIPROT:P56851 - FACTA Search

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

The present paper demonstrates the presence of at least two 3-hydroxysteroid oxidoreductases (3-HSO) in rat testis, prostate, and epididymis cytosol preparations. The enzymes were either NADH or NDAPH dependent. Further investigation by Sephadex G-200 chromatogrphy revealed the presence of enzyme activities in the void volume (peak 1) and also eluting close to the methyl-carbonic anhydrase standard (mol wt, 34,000; peak 2). Enzyme activity in peak 1 was predominantly stimulated by NADH and that in peak 2 was stimulated mainly by NADPH. Both 3 alpha- and 3 beta-HSO activities were observed in testicular eluates from 1; 3 beta-Adiol accounted for up to 50% of the 5 alpha-androstanediols formed. In peak 2,3 alpha-HSO constituted more than 90% of the enzyme activity. In contrast, the prostatic and epididymal eluates revealed only 3 alpha-HSO activity; 3 beta-Adiol constituted less than 5% of the 5 alpha-androstanediols formed in either peak 1 or 2. The apparent Km values for enzyme activation reveal differences in sensitivity to cofactors for enzymes in peaks 1 and 2 and also among testis, epididymis, and prostate. NADH caused a very similar activation of enzyme activity in peak 1 or the prostate and epididymis (Km 50-100 micro M), whereas the enzyme in the testis was activated by much lower cofactor concentration (Km approximately 5 microM). It is possible that this enzyme activity may represent microsomal contamination. The enzyme activity in peak 2 revealed very similar sensitivity to NADPH in all three organs (Km, 0.6-1.7 microM), confirming previous studies from our laboratory that the soluble. NADPH-dependent enzymes in all three tissues are very similar, if not identical.
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PMID:Cofactor dependency of soluble 3 alpha-hydroxysteroid oxidoreductases in rat testis, prostate, and epididymis. 693 64

When [4-14C]-5 alpha-dihydrotestosterone was incubated with the homogenate of human epididymis, 5 alpha-androstane-3 alpha, 17 beta-diol and 5 alpha-androstane-3 beta, 17 beta-diol were identified as major metabolites. The ratio of 3 alpha- to 3 beta-epimer in androstanediol formation was approximately 2.4. 5 alpha-Androstane-3, 17-dione was also identified as a minor metabolite. Among the subcellular fractions, both the human epididymal 3 alpha- and 3 beta-hydroxysteroid dehydrogenases were localized almost exclusively in the cytosol fraction (105,000 X g supernatant). Both enzymes had optimum pH at 7.5 and optimum temperature at 46 degrees C. NADPH was a more preferable cofactor than NADH for both dehydrogenases. The Michaelis constants (Km) of 3 alpha- and 3 beta-hydroxysteroid dehydrogenase for 5 alpha-dihydrotestosterone were similar and estimated as 8 X 10(-5) M, but the enzymes were unsaturable with the substrate under the conditions investigated, indicating low affinity and high capacity of both dehydrogenases for 5 alpha-dihydrotestosterone. The human epididymal 5 alpha-reductase revealed a regional difference in activity. The 5 alpha-reductase activity in the most proximal part of the head (ductuli efferentes) was one seventh to one tenth the activity in the remaining part of the epididymis which was constructed of ductus epididymis. Except for this finding, the activity of 5 alpha-reductase was highest in the head, then declined along the course to the tail portion. The 5 alpha-reductase for testosterone was competitively inhibited by delta 4-3-oxosteroids such as progesterone, 20 alpha-dihydroprogesterone, 17 alpha-hydroxyprogesterone, 4-androstenedione, 11-deoxycorticosterone, corticosterone and 11-deoxycortisol, which had inhibition constants (Ki) of 3.3 X 10(-9) M, 2.2 X 10(-9) M, 1.8 X 10(-8) M, 1.3 X 10(-8) M, 8.3 X 10(-9) M, 1.5 X 10(-7) M and 8.7 X 10(-8) M, respectively, suggesting the possibility that the 5 alpha-reduction of testosterone is regulated by other delta 4-3-oxosteroids.
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PMID:Studies on the human epididymis: partial characterization of 3 alpha- and 3 beta-hydroxysteroid dehydrogenase, regional distribution of 5 alpha-reductase and inhibitory effect of 4 delta-3-oxosteroids on 5 alpha-reductase. 696 21

The specific activities of the fatty acid synthetases in the cytosolic fraction of livers and epididymal fat pads from fed, fasted or refed rats were determined. Refed rats received diets which provided, as the primary energy sources, sucrose or starch (75%) or both (59%) with beef tallow or safflower oil (16%) or the monosaccharide components (75%). From these determinations of fatty acid synthetase activity, the relative contribution of each tissue to the rat's overall lipogenic capacity was estimated. In rats fed a cereal-based stock diet ad libitum the adipose tissue accounted for 58% of total activity. During a 2-day fast the hepatic activity decreased from 14 units/100 g body weight to 2.7 units whereas the adipose tissue activity fell from 19 to 13.4 units/100 g body weight. At this time, 82.8% of the activity was in the latter tissue. After refeeding the sucrose diet for 2 days, the hepatic activity had increased 45-fold to 122.3 units/100 g body weight while the adipose tissue activity increased only 2.2-fold to 29.1 units, 19% of the total activity. We estimate that these adaptive responses deteriorate slowly (12.3 days, adipose tissue: 15.4 days, liver) with continued refeeding to the levels present in rats fed the cereal-based stock diet. Activation of residual or constituative enzyme was the major factor in the adipose tissue response whereas activation and induction played roles in the hepatic response. Responses to the refeeding of the other diets were of lesser magnitude. Generally our estimates based on fatty acids synthetase activities are consistent with other estimates based on radiolabel incorporation, NADPH generation and rate-limiting enzyme activities.
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PMID:Comparative studies of adaptive responses of fatty acid synthetase activities in rat liver and adipose tissue. 729 96

A systematic investigation of potential ligands for the affinity purification of aldehyde reductase (alcohol:NADP+ oxidoreductase, EC 1.1.1.2.) has been carried out. The most suitable nucleotide ligands tested were NADP+ and 2',5'-ADP. Adsorbed enzyme could be eluted with NADPH but not NADH. The chlorotriazinyl dyes Cibacron Blue F3GA and Procion Red HE3B also proved effective as 'affinity' ligands when immobilized to Sepharose 4B. The free dyes and also Blue Dextran (Cibacron Blue F3GA coupled to dextran) were all potent inhibitors of aldehyde reductase. The inhibition by Blue Dextran was shown to be competitive with respect to NADPH (Ki = 1.8 x 10(-7) M). The enzyme was sensitive to inhibition by glutaric acid derivatives, flavonoids and a range of anti-convulsants.
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PMID:Isolation and characterization of rat liver aldehyde reductase. 744 91

Male germ cells at various stages of differentiation from pachytene spermatocytes to mature caudal epididymal spermatozoa were examined for their ability to generate reactive oxygen species (ROS) using sensitive chemiluminescence techniques. In general, spermatozoa were found to spontaneously generate hydrogen peroxide as they progressed through the epididymis, maximal activity being observed on the release of mature cells from the caudal region into a modified Krebs-Ringer's solution. The spontaneous production of hydrogen peroxide rose rapidly during the first 10 min after the spermatozoa had been diluted into culture medium and thereafter stabilized, neither phorbol esters nor A23187 subsequently influencing this activity. Low levels of superoxide generation were also detected in suspensions of epididymal spermatozoa, but did not correlate with maturation status. However, superoxide production could be dramatically enhanced by the addition of exogenous NADPH, in a manner that was closely correlated with the stage of epididymal development being maximal for immature cells recovered from the caput epididymis in all species. Precursor germ cells (pachytene spermatocytes, round and elongate spermatids) similarly generated chemiluminescent signals compatible with the low level generation of ROS. Superoxide generation in these cells could again be stimulated by NADPH, via mechanisms that were inversely related to the stage of germ cell differentiation, the greatest activity being observed in pachytene spermatocytes. These results demonstrate that differentiating male germ cells have the potential to generate ROS, and have implications for the redox regulation of gonadal function and the development of reproductive pathologies involving oxidative stress.
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PMID:Comparative analysis of the ability of precursor germ cells and epididymal spermatozoa to generate reactive oxygen metabolites. 912 58

Glucose metabolism is essential for successful gamete fusion in the mouse. Although the metabolic activity of the oocyte does not appear to play a significant role in the fusion step, the metabolic role of the spermatozoon is not known. The aim of this study was therefore to characterize the role of glucose metabolism in mouse spermatozoa. Initially, the high-affinity glucose transporter GLUT3 was identified in mouse sperm. In characterizing the glucose metabolism of mouse sperm, we have shown 1) that mouse epididymal spermatozoa have a functional pentose phosphate pathway (PPP), implying that they produce NADPH, which is required for reducing reactions, and ribose 5-phosphate, which is required for nucleic acid synthesis; and 2) that sperm are able to fuse with the oocyte when NADPH is substituted for glucose, suggesting that sperm need to produce NADPH via the PPP in order to be able to achieve fertilization. The existence of an NADPH-regulated event that influences the ability of the sperm to fuse with the oocyte is envisaged.
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PMID:A possible role for the pentose phosphate pathway of spermatozoa in gamete fusion in the mouse. 1002 24

Rat spermatozoa from both the caput and cauda epididymidis were shown to generate superoxide anion (O2-.) both spontaneously and following stimulation with NAD(P)H. Caput spermatozoa gave a significantly greater O2- response to NADPH stimulation than caudal cells, whereas in both cell types the responses to exogenous NADPH and NADH were approximately equivalent. Analysis of H2O2 production revealed that this oxidant was generated only by caudal epididymal cells and only in these cells did the stimulation of reactive oxygen species (ROS) production with NADPH lead to an increase in tyrosine phosphorylation. Stimulation of ROS production with NADPH increased intracellular cyclic adenosine monophosphate (cAMP) levels in both caput and caudal epididymal cells, but only in caudal cells did cAMP stimulate tyrosine phosphorylation, in keeping with the NADPH results. On the basis of these findings we propose that tyrosine phosphorylation in rat spermatozoa is driven by ROS acting via 2 different but complementary mechanisms; O2-. stimulates tyrosine kinase activity indirectly through the elevation of intracellular cAMP while H2O2 acts directly on the kinase/phosphatase system, stimulating the former and inhibiting the latter. Zinc was examined as a potential regulator of this signal transduction cascade and was shown to suppress tyrosine phosphorylation in caput cells but to promote this activity in caudal spermatozoa, possibly through an inhibitory effect on tyrosine phosphatase activity. These results reveal the maturation of a redox-regulated, cAMP-mediated, signal transduction cascade during epididymal transit in the rat that is sensitive to zinc and plays a key role in the control of tyrosine phosphorylation events associated with capacitation.
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PMID:A redox-regulated tyrosine phosphorylation cascade in rat spermatozoa. 1145 58

Reactive oxygen species scavengers present in male accessory sex gland secretions might afford antioxidant protection to sperm DNA. This study was conducted to determine whether accessory sex gland secretions protect the genome and function of spermatozoa against oxidative damage in the uterus. Male golden hamsters were divided into four experimental groups: (i) all accessory sex glands removed; (ii) ampullary glands removed; (iii) ventral prostate gland removed and (iv) sham-operated controls. Ejaculated spermatozoa recovered from uteri 15-30 min after mating with experimental males and caput and cauda epididymal spermatozoa obtained from intact males were incubated in 0-20 mmol NADPH l(-1) for 2 h. These spermatozoa and untreated uterine spermatozoa were processed for two types of comet assay (single cell gel electrophoresis): alkaline comet assay (pH > 13) which revealed single-strand DNA breakage and neutral comet assay (pH 9) which revealed double-strand DNA breakage. In comparison with the sham-operated controls, spermatozoa that had not been exposed to accessory sex gland secretions had a higher incidence and more extensive single-strand DNA damage with increasing concentrations of NADPH. Spermatozoa from hamsters without ampullary glands and from hamsters without the ventral prostate glands were similar to those of the control group. After incubation with NADPH, the capacity of spermatozoa from hamsters without accessory glands and from sham-operated controls to fuse with oocytes in vitro was reduced. However, only hamsters without accessory glands showed a negative correlation between single-strand DNA damage and sperm-oocyte fusion. Cauda epididymal spermatozoa were less susceptible to NADPH treatment compared with caput epididymal spermatozoa. The results of the present study showed that male accessory sex gland secretions can preserve the integrity of the sperm genome.
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PMID:Protection of sperm DNA against oxidative stress in vivo by accessory sex gland secretions in male hamsters. 1236 67

We have investigated the potential of the male reproductive tract to accumulate trichloroethylene (TCE) and its metabolites, including chloral, trichloroethanol (TCOH), trichloroacetic acid (TCA), and dichloroacetic acid (DCA). Human seminal fluid and urine samples from eight mechanics diagnosed with clinical infertility and exposed to TCE occupationally were analyzed. In in vivo experimental studies, TCE and its metabolites were determined in epididymis and testis of mice exposed to TCE (1000 ppm) by inhalation for 1 to 4 weeks. In other studies, incubations of monkey epididymal microsomes were performed in the presence of TCE and NADPH. Our results showed that seminal fluid from all eight subjects contained TCE, chloral, and TCOH. DCA was present in samples from two subjects, and only one contained TCA. TCA and/or TCOH were also identified in urine samples from only two subjects. TCE, chloral, and TCOH were detected in murine epididymis after inhalation exposure with TCE for 1 to 4 weeks. Levels of TCE and chloral were similar throughout the entire exposure period. TCOH levels were similar at 1 and 2 weeks but increased significantly after 4 weeks of TCE exposure. Chloral was identified in microsomal incubations with TCE in monkey epididymis. CYP2E1, a P450 that metabolizes TCE, was localized in human and monkey epididymal epithelium and testicular Leydig cells. These results indicated that TCE is metabolized in the reproductive tract of the mouse and monkey. Furthermore, TCE and its metabolites accumulated in seminal fluid, and suggested associations between production of TCE metabolites, reproductive toxicity, and impaired fertility.
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PMID:Identification of trichloroethylene and its metabolites in human seminal fluid of workers exposed to trichloroethylene. 1258 57

Recently, we reported that male accessory sex gland (ASG) secretions protect sperm genomic integrity by demonstrating that DNA damage was more extensive in sperm not exposed to the secretions. The present study was conducted to find out if ASGs secrete the main antioxidant enzymes superoxide dismutase (SOD), glutathione peroxidase (GPx or GSH-Px), and catalase (CAT) and if the most abundant one, SOD, can protect those sperm that were not exposed to ASG secretions against NADPH-induced oxidative stress. Four experimental groups of male golden hamsters were used: intact animals with proven fertility, animals with all major ASGs removed (TX), animals that were bilaterally vasectomized, and sham-operated controls. SOD, CAT, and GPx activities were measured in secretions from all 5 ASGs and sperm-free uterine flushing from virgin females and those mated with the experimental males. The alkaline comet assay was used to analyze DNA integrity of the TX group sperm after incubation in a medium containing 50 U/mL of SOD along with 0 to 20 mmol/L NADPH. The main antioxidant enzyme in ASGs was SOD from coagulating glands (P <.05) and GPx together with CAT from ampullary glands (P <.05). Uterine flushing of ejaculates that contained ASG secretions had more SOD and CAT activities than those with epididymal secretions alone (P <.05 and P <.001, respectively), whereas activity of GPx was the same (P >.05). Addition of SOD in vitro dose dependently decreased the incidence of single-strand DNA damage in sperm not exposed to ASG secretions incubated in the presence of 0 to 20 mmol/L NADPH (P <.001). These results indicated that, in terms of abundance, SOD was the main antioxidant enzyme secreted by male ASGs, whereas CAT was the second one. The GPx activity came from both epididymis and ASGs. We conclude that ASG secretions play a significant role in protecting sperm against oxidative stress.
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PMID:Male genital tract antioxidant enzymes: their source, function in the female, and ability to preserve sperm DNA integrity in the golden hamster. 1295 61

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