Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01178 (oxytocin)
 15,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The peptide oxytocin is present in tissues of the male reproductive tract from a variety of mammalian species. In the human, specific mRNA for oxytocin and the peptide itself have been identified in the testis, epididymis and prostate. The peptide has been shown to modulate both steroidogenesis and contractility in the male reproductive tract and may be involved in the pathogenesis of benign prostatic hyperplasia. We have performed Western blots and immunohistochemistry using a specific antibody to the human oxytocin receptor (OTR) to investigate the distribution and localization of the receptor in the human and macaque monkey (Macaca fasicularis). An immunoreactive band of approximately 55 kDa was detected in human and monkey uterine, testicular and prostatic tissues and in preparations of monkey caput and cauda epididymis. A second, less intense, band of 60 kDa was also seen in testicular and uterine tissue samples. No specific bands were detected in monkey muscle or in any tissue following incubation with mouse immunoglobulin (Ig)M. In the human and monkey testis staining for the OTR was present in the interstitial tissue and in Sertoli cells. Localization of the OTRs varied throughout the epididymis being expressed by epithelial cells proximally but confined to cells at the base of the epididymal ducts and to the surrounding smooth muscle layers distally. In the prostate OTR were localized to the stromal tissue surrounding the ducts. These findings correlate with sites of local production of the peptide and the observed biological actions of oxytocin, and thus support the evidence that oxytocin may play a physiological role in the male reproductive tract.
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PMID:Localization of oxytocin receptors in the human and macaque monkey male reproductive tracts: evidence for a physiological role of oxytocin in the male. 966 35

It has been suggested that oxytocin is involved in sperm transport and motility in domestic animals. Immunoreactive oxytocin was measured in seminal fractions (pre-ejaculatory fluid, seminal plasma, gel and sperm) and in extracts of testis and epididymis from stallions. In addition, sections of gonadal tissue from stallions were immunostained for the presence of oxytocin and its neurophysin. Oxytocin was detected in all of the seminal fractions, being highest in the gel. It was also present in washed, lysed sperm and in extracts from the testis and epididymis. Immunostaining for oxytocin was present in occasional interstitial cells in the testis and in the epididymal epithelium and smooth muscle. However, immunostaining for neurophysin was detected in a few interstitial cells in the testis of only 1 of 8 stallions and was absent from all areas of the epididymis. These data demonstrate for the first time the presence of oxytocin in stallion semen and gonadal tissue; however, lack of immunostaining for neurophysin indicated that it was unlikely that there was local synthesis within the gonads.
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PMID:Oxytocin in the semen and gonads of the stallion. 1072 8

Contractions of seminiferous tubules and epididymal duct walls promote spermiation and sperm transfer, and they are thought to be stimulated by the related peptides oxytocin and vasopressin. This study tested the hypothesis that if oxytocin and/or vasopressin play a physiological role in sperm shedding and transport, then local or circulating concentrations of these peptides would increase during puberty. Testes, epididymides, and trunk blood of sheep at stages during the first spermatogenic wave were collected, and radioimmunoassay measured significant increases in testicular and epididymal oxytocin during spermatogenesis. No changes were measured in circulating oxytocin or in local or circulating vasopressin. Localization and synthesis was investigated by immunohistochemistry and Western blot analysis employing antibodies recognizing epitopes of either oxytocin, oxytocin-associated neurophysin, vasopressin, or vasopressin-associated neurophysin. Marked expression of both oxytocin and its associated neurophysin in testicular Leydig and epididymal principal cells was seen, and weak neurophysin immunoreactivity was also identified in Sertoli cells. The intercellular distribution of oxytocin varied between regions of the epididymis, suggesting several roles for oxytocin. Vasopressin synthesis was not apparent in either tissue. These results confirm the presence and development of paracrine oxytocinergic systems in the ram testis and epididymis of ram during puberty while questioning the physiological importance of vasopressin.
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PMID:Oxytocin and vasopressin expression in the ovine testis and epididymis: changes with the onset of spermatogenesis. 1090 49

Oxytocin is present in the male reproductive tract and has been shown to increase contractility in the epididymis and to modulate steroidogenesis. This study investigated the effects of oxytocin in the testis in vivo, and the presence and cellular localization of oxytocin receptors in the reproductive tract of rams. During the breeding season, mature rams underwent efferent duct ligation before injection of either oxytocin (20 microg) or oxytocin plus an oxytocin antagonist (20 microg) into the testicular artery; the contralateral testicular artery received saline. Injection of oxytocin caused a significant increase (P < 0.05) in the concentration of spermatozoa collected from the rete testis. This effect was not observed after treatment with the oxytocin antagonist plus oxytocin. Western blot analysis performed using a specific oxytocin receptor antibody (020) identified a single immunoreactive band of 66 kDa in testicular and epididymal tissue. This band was present in uterine tissue but not in liver or muscle. Immunocytochemistry identified oxytocin receptors on Leydig and Sertoli cells of the testis, on epithelial cells throughout the epididymis, on peritubular smooth muscle cells in the cauda epididymidis, and on the epithelial cells and circular smooth muscle layer of the ductus deferens. These findings indicate that oxytocin can modulate sperm transport in the ram testis. A role for oxytocin in promoting sperm transit is supported by the localization of oxytocin receptors in the cauda epididymis and ductus deferens, and the presence of receptors on Leydig, Sertoli and epididymal epithelial cells provides further evidence that oxytocin may be involved in the local regulation of steroidogenesis.
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PMID:Function and localization of oxytocin receptors in the reproductive tissue of rams. 1146 83

Spermatogenesis is a complex process during which developing germ cells move from the base of the seminiferous tubule towards the lumen where they are shed. Studies in the rat suggest that seminiferous tubule contraction, induced by exogenous oxytocin, promotes spermiation. This study examines the role of testicular oxytocin in development of the testes, spermatogenesis and spermiation in the mouse. Groups of wild-type (WT) mice, oxytocin knockout mice (OTKO) deficient in testicular oxytocin and mice containing an oxytocin transgene (bOT4.2) that over express testicular oxytocin were killed between days 5 and 45 post partum. The testes and epididymides were removed weighed and prepared either for histological and morphometric study by light microscopy, for sperm counts (epididymis), or extracted for determination of oxytocin content (testis - day 45 only). Testicular oxytocin concentrations were significantly greater (p < 0.05) in bOT4.2 mice than in WT or OTKO mice. No differences in testicular and epididymal weight, or in diameter and area of seminiferous tubules between the mice genotypes were found at any given time. Germ cell development was similar in all genotypes and was comparable with previous studies. The timing of spermiation between the groups was significantly different (p < 0.001) with bOT4.2 < WT < OTKO and the appearance of epididymal sperm was significantly different (p < 0.05) with bOT4.2 < WT < OTKO. There were significant correlations between the percentage of tubules containing residual bodies and epididymal sperm count (p < 0.05) and between the percentage of animals containing residual bodies and the percentage of animals containing epididymal sperm (p < 0.01). These data suggest that in the mouse oxytocin, whilst not involved in germ cell development, is important in the process of spermiation and sperm transfer in the mouse.
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PMID:Oxytocin promotes spermiation and sperm transfer in the mouse. 1186 73

Oxytocin (OT) and arginine vasopressin (AVP) have been found to be present in the reproductive system of the mammalian male, but their function in this system is unclear. This study examined the effects of these two hormones on contractions of the rat caput epididymis, as well as the hormones' effects on epididymal diameter during contractions. The initial segments of caput epididymides were observed in vitro in a solution of modified Tyrode's solution, with a test solution containing a concentration of either OT or AVP being added after a 5-min period. The frequency and diameter of the epididymal contractions were measured before and after addition of each test solution. Also observed was the effect of magnesium concentrations on the ability of OT to induce changes in epididymal contractility. This study found that the frequency of epididymal contractions increase and that the diameter of the epididymal tubules decrease proportionally during contractions with the addition of either OT or AVP. Furthermore, we noted that Mg++ has an inverse correlation with the frequency of contractions of the caput epididymis both in the presence and absence of OT. These findings suggest that both OT and AVP may have a role in regulating epididymal contractility and thus, perhaps, sperm transport through that organ.
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PMID:The effects of oxytocin and arginine vasopressin in vitro on epididymal contractility in the rat. 1190 55

Oxytocin (OT) is a neurohypophysial hormone with unclear physiological functions in the male. Several previous studies indicated that OT might have a role in the ejaculatory process, stimulating sperm release from the epididymal storage. In this study we investigated on the presence and function of OT receptor (OTR) in rabbit and human epididymis. By using RT-PCR, Western and binding studies, we found that OTR gene and protein is expressed in the human epididymis and stimulates in vitro contractility. The immunolocalization of OTR suggests that the receptor is not only present in the smooth muscle cells of the human epididymis but also in the epithelial compartment. Experiments performed in rabbit epididymal epithelial (rEE) cells in culture indicate that OT induces the release of an other potent stimulator of epididymal contractility, endothelin-1 (ET-1), Blocking the ET(A) subtype of the ET-1 receptors, by using a specific antagonist (BQ-123), partially counteracts the contractile effect of OT, suggesting positive interactions between the two peptides in regulating epididymal contractility. Finally, to investigate whether an acute OT administration increases sperm release also in humans, we treated oligozoospermic patients with an intravenous bolus of OT (2.5 IU), just before sperm collection. In a small, single blind study, we found that OT almost doubled sperm retrieval when compared with vehicle administration. Our results indicate that OT might have physiological functions also in the male, controlling epididymal motility and sperm progression through the male genital tract.
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PMID:Identification, localization and functional activity of oxytocin receptors in epididymis. 1216 Oct 7

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

Oxytocin (OT) modulates adult mammalian sexual behavior, sperm production and transport, and steroidogenesis; however, the consequences of developmental manipulations of oxytocin have received little attention. The purpose of this experiment was to determine whether neonatal exposure to OT, an oxytocin antagonist (OTA), saline (SAL), or handling (HAN)-only would have long-term effects on reproductive potential in male prairie voles (Microtus ochrogaster). Adult males were observed for 24 h with a sexually receptive female and sexual behavior was recorded. Females were subsequently lavaged and smears were examined for sperm. Reproductive parameters including motility of epididymal sperm, testis weight, and plasma androgen levels were in the normal range. OT-treated males that did not mate within the first 30 min did not mate at all, and in comparison to controls, a higher proportion of those OT-treated and OTA-treated males that did mate did not transfer sperm to the females. OTA-treated males also had significantly higher testicular sperm concentrations than HAN-only males, and significantly lower epididymal sperm concentrations. These differences suggest that in males, developmental manipulations of OT may have the potential to influence the subsequent expression of sexual behavior and sperm transport.
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PMID:Effects of neonatal oxytocin manipulations on male reproductive potential in prairie voles. 1513 25

The only safe method of male contraception is vasectomy, with high reversibility secured by microsurgery. Italy, however, suffers from a lack of regulations on this subject. Hormonal treatment (testosterone plus progestational hormones) is far from providing reliability and safety, while some perspectives, theoretical only for the time being, are offered by studies on functional infertility induced by either speeding up (ganglioplegic, sympathomimetic, parasympatholytic, oxytocin, endothelin, angiotensin) or inhibiting (sympatholytic) the sperm transport through the epididymis, or altering the epididymal environment (alpha-chloridin, chlorodeoxyglucose).
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PMID:[Male contraception]. 1553 63


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