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)

Lytochrome P450 aromatase is a microsomal enzyme catalyzing the conversion of androgens to estrogens. P450arom expression has been demonstrated in testicular and epididymal sperm cells of several species but very limited data have been reported about maturating human germ cells. In this study, human spermatozoa with cytoplasmic droplet anomaly have been utilized to investigate aromatase immunolocalization in the immature germ cells of human ejaculate. Immunodetection has utilized a polyclonal antiserum as primary antibody, a biotinylated IgG as secondary antibody and then the avidin-biotin-peroxidase complex amplification followed by the diaminobenzidine staining. A strong immunoreaction was observed in the cytoplasmic droplets retained around the midpiece of immature spermatozoa and also in the descending droplets of late maturing sperm, while the other cellular components were unstained. Therefore, this investigation has demonstrated, for the first time, aromatase immunolocalization in residual cytoplasm of human ejaculated sperm, suggesting cytoplasmic droplets as possible estrogen biosynthesis sites during human sperm differentiation.
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PMID:Evidence of aromatase localization in cytoplasmic droplet of human immature ejaculated spermatozoa. 1270 75

Oxytocin (OT) is a neurohypophysial hormone with overall unclear physiological functions in the male. Several studies indicated that OT has a key role in the central regulation of penile erection. In this mini-review we summarize its possible involvement in another aspect of the male sexuality: the ejaculatory process. Because OT is released by posterior pituitary at the time of orgasm, we postulate that OT might help sperm progression during ejaculation. Our recent studies indicate that OT receptors (OTR) are present in rabbit and human epididymis and mediate contractility. Accordingly, they are immuno-localized in the smooth muscle cells of the epididymis. However, they are also present in the epithelial compartment of the tubules. In epididymal epithelial cells in culture, OT induces the release of another potent stimulator of epididymal contractility, endothelin-1 (ET-1), which most probably amplifies OT-induced contraction. Sex steroids regulate the density of OTR in epididymis. In fact, in an experimental model of hypogonadotropic hypogonadism (hypo) induced in rabbits, estrogens, but not androgens, fully restored OT-induced epididymal contractility, up-regulating OTR gene and protein expression. In addition, deprivation of endogenous estrogens, by blocking their formation using the aromatase inhibitor letrozole, induced OT hypo-responsiveness comparable to that observed in hypo rabbits. These findings suggest a new function of estrogens in the male: regulation of OT responsiveness in epididymis.
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PMID:Role of oxytocin in the ejaculatory process. 1283 28

Abstract Cytochrome P450 aromatase is a terminal enzyme that catalyses the conversion of androgens into oestrogens. This study investigated the immunohistochemical localization of aromatase in human efferent ductules and proximal ductus epididymis using a mouse anti-human monoclonal P450arom IgG as primary antibody and a goat anti-mouse biotinylated IgG as secondary antibody. A strong immunoreaction was observed in the epithelial cell cytoplasm of both ductuli efferentes and proximal ductus epididymis, whereas the smooth muscle cells were immunonegative in the two regions. The results show, for the first time in humans, that epithelial cells of ductuli efferentes and proximal caput epididymis express aromatase, suggesting that locally produced oestrogens may have a role in epididymal function.
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PMID:Aromatase immunolocalization in human ductuli efferentes and proximal ductus epididymis. 1503 11

Epididymis is a sex steroid (androgen + estrogen)-sensitive duct provided with spontaneous motility, allowing sperm transport. We previously reported that the oxytocin (OT) receptor (OTR) mediates an estrogen-dependent increase in epididymal contractility. Because endothelin (ET)-1 also regulates epididymal motility, we tested its sex steroid dependence in a rabbit model. We demonstrated that estrogens up-regulate responsiveness to ET-1, which is reduced by blocking aromatase activity (letrozole, 2.5 mg/kg) or by triptorelin (2.9 mg/kg)-induced hypogonadism, whereas it is fully restored by estradiol valerate (3.3 mg/kg weekly) but not by testosterone enanthate (30 mg/kg weekly). However, changing sex steroid milieu did not affect either ET-1, its receptor gene, or protein expression. Two structurally distinct OTR-antagonists [(d(CH2)5(1), Tyr(Me)(2), Orn(8))-OT and atosiban] almost completely abolished ET-1 contractility, without competing for [125I]ET-1 binding, suggesting that OT/OTR partially mediates ET-1 action. Immunohistochemical studies in human and rabbit epididymis demonstrated that both OT and its synthesis-associated protein, neurophysin I, are expressed in the epithelial cells facing the muscular layer, suggesting local OT production. Quantitative RT-PCR demonstrated a high abundance of OT transcripts in human epididymis. OT transcript was also originally detected and partially sequenced in rabbit epididymis. To verify whether ET-1 regulates OT release, we used rabbit epididymal epithelial cell cultures. These cells expressed a high density of [125I]ET-1 binding sites and responded to ET-1 with a dose-dependent OT release. Hence, we propose that an ET-1-induced OT/OTR system activation underlies the estrogen-dependent hyperresponsiveness to ET-1. These local sources might promote the spontaneous motility necessary for sperm transport.
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PMID:Oxytocin mediates the estrogen-dependent contractile activity of endothelin-1 in human and rabbit epididymis. 1586 May 58

Estrogen plays an essential role in male reproduction. In human and other mammalians, a number of tissues express aromatase and hence synthesize estrogen. ERs and aromatase are present at all developmental stages of the male reproductive organs in many mammalian species. Estrogen is important in different aspects in male reproductive physiology, including its effects on germ cells, Sertoli cells, Leydig cells and epididymal functions.
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PMID:[Role of estrogen in male reproduction]. 1633 67

The epididymal epithelial cells of rats in vitro display features of steroidogenic cells. The cells produce and release androgens into the culture medium that are converted to 17beta-estradiol (E2) due to the activity ofcytochrome P450 aromatase. It is probable that steroidogenesis in epididymal epithelial cells of rat is regulated by luteinizing hormone (LH). The aim of the study was to estimate the influence of hCG on the morphology of epididymal epithelial cells and synthesis of E2 by the cells. In conclusion, the hCG stimulation results in changes of the cell morphology, similar to those observed in Leydig cells and increase synthesis of the 17beta-estradiol due to the presence of LH/hCG receptors.
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PMID:[Regulation of steroidogenesis in rat epididymal epithelial cells]. 1652 72

The primary source of 17beta-estradiol (E2) in the male is the testis, which expresses the enzyme complex aromatase that is involved in E2 biosynthesis. However, recent evidences suggest that the epididymis is also capable of E2 biosynthesis. Our results demonstrate the presence of cytochrome P450 aromatase (P450(AROM)) and 17beta-hydroxysteroid dehydrogenase I messenger ribonucleic acid (mRNA) in the caput and cauda regions of rat epididymis. The androgenic substrates testosterone and androstenedione could be utilized by the rat epididymal aromatase for E2 biosynthesis as assessed by radioimmunoassay. P450(AROM) expression is transcriptionally regulated in a tissue-specific manner by various factors including androgens and luteinizing hormone (LH). Androgens could positively modulate epididymal P450(AROM) mRNA levels as assessed by castration studies, treatment with flutamide or in vitro incubation of tissue minces with 5 alpha-dihydrotestosterone (DHT). Several extra-gonadal tissues including the epididymis are known to express LH receptors (LHR). Our study revealed a higher level of LHR mRNA expression in the cauda region compared to the caput. Caudal membrane extracts could bind human chorionic gonadotropin (hCG), which resulted in the production of cAMP. Interestingly, hCG could also regulate P450(AROM) mRNA expression in vitro and enhance E2 biosynthesis. Together our results highlight the presence of a functional aromatase in the epididymis that is subject to regulation by LH and androgens.
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PMID:Expression of functional aromatase in the epididymis: role of androgens and LH in modulation of expression and activity. 1656 75

Exposure to the Roundup has been shown to affect StAR protein and aromatase expression and activity, pointing out that this herbicide may cause adverse effects in animal reproduction by affecting androgen and estrogen synthesis. We tested this hypothesis by investigating the in vivo effects of the Roundup on the testis and epididymal region of drake Anas platyrhynchos. The exposure to the herbicide resulted in alterations in the structure of the testis and epididymal region as well as in the serum levels of testosterone and estradiol, with changes in the expression of androgen receptors restricted to the testis. The harmful effects were more conspicuous in the proximal efferent ductules and epididymal ducts, suggesting higher sensitivity of these segments among the male genital organs. The effects were mostly dose dependent, indicating that this herbicide may cause disorder in the morphophysiology of the male genital system of animals.
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PMID:Effects of the herbicide Roundup on the epididymal region of drakes Anas platyrhynchos. 1716 97

The study presented herein was designed to test the hypothesis that reduced endogenous estrogen in the boar alters efferent duct morphology, epididymal morphology, and steroid receptor expression. Twenty-eight littermate pairs of boars were treated with Letrozole, an aromatase inhibitor, or with vehicle from 1 week of age until castration at 2 through 8 months. Efferent ducts and epididymides were examined for morphological development and steroid receptor expression. Efferent duct morphology was not different between control and Letrozole-treated animals at any examined age. Androgen receptor (AR), estrogen receptor alpha (ERalpha), and beta (ERbeta) were expressed in the epithelial cells of the efferent ducts at all ages; expression was similar in control and treated animals. Morphological development of the caput and corpus was delayed in Letrozole-treated animals, but this delay was transient since morphology was similar between control and treated animals at 8 months. The cauda did not show a delay in development, but was more developed in treated animals at 2 months. AR, ERalpha, and ERbeta were expressed in all three epididymal regions; no difference was observed between control and treated animals. In summary, estrogen appears to be important for development of the epididymis; however, the cauda may be regulated differently than the caput and corpus. Results for the efferent ducts suggest that the normally high endogenous estrogens are not required for regulation of fluid reabsorption in the boar. It also suggests that any ER activation required for maintenance of efferent duct morphology and function is normal in Letrozole-treated boars.
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PMID:Reduced endogenous estrogen delays epididymal development but has no effect on efferent duct morphology in boars. 1789 Feb 95

Increased Sertoli cell proliferation during the neonatal period, transient negative effects on epididymal sperm maturation, larger postpuberal testis size reflective of increased Sertoli cell numbers, and increased testicular sperm production characterized boars subjected to continuous inhibition of endogenous estrogen production. The objective in the present experiment was to extend these previous observations to evaluate the effects of a shorter period of reduced estrogen production during the neonatal and juvenile periods on Sertoli cell proliferation, postpuberal testis size, sperm production and epididymal function. Experiments were designed to detect cumulative effects on accessory sex glands as well. Four pairs of littermate boars were assigned to the experiment with one member of each pair randomly selected to receive weekly oral treatment with the aromatase inhibitor, Letrozole, beginning at 1 week of age; the littermates received weekly oral treatment with the corn oil vehicle. Treatment stopped at 12 weeks of age and effects were examined at 10 months. Treated animals had approximately 25% larger testes (P<0.05) correlated with increased Sertoli cell numbers (P<0.05) and larger epididymides. Sperm quality was approximately equivalent in treated and control littermates. Accessory sex glands tended to be smaller in the treated boars. Sertoli cell proliferation during the neonatal and juvenile interval appears to be influenced by endogenous estrogen levels in the boar. A relatively short postnatal interval of Letrozole treatment effectively increased postpuberal testis size. Increased sperm production capacity in response to decreased endogenous estrogens has intriguing possibilities for animal agricultural production.
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PMID:Reducing endogenous estrogens during the neonatal and juvenile periods affects reproductive tract development and sperm production in postpuberal boars. 1800 55


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