Biomedical subjects

Gianni Forti

Publications and source records attributed to Gianni Forti.

At least 19 recordsLinked to original sources

PubMed2006

Characterization and functional role of androgen-dependent PDE5 activity in the bladder.

Benign prostate hyperplasia is the most common disease in the aging male, often comorbid with erectile dysfunction. Phosphodiesterase type 5 (PDE5) inhibitors (sildenafil, tadalafil, and vardenafil) decrease lower urinary tract symptoms in patients with erectile dysfunction and BPH. We studied PDE5 expression and activity in the human bladder and PDE5i effects both in vitro (human and rat) and in vivo (rat). PDE5 is highly expressed in rat and human bladder and immunolocalized in vascular endothelium and muscle fibers. Sildenafil, tadalafil, and vardenafil blocked 70% of the total cGMP-catabolizing activity; vardenafil was the most potent (IC(50) = 0.3 nm). In human bladder cells and in rat strips, a PDE-resistant cGMP analog, SP-8-Br-PET-cGMPS, induced, respectively, a consistent antiproliferative and relaxant effect. In contrast, the nitric oxide donor sodium nitroprusside (SNP) was almost ineffective. However, blocking PDE5 with vardenafil increased SNP antiproliferative and relaxant activity up to the level observed with SP-8-Br-PET-cGMPS. We also found that castration decreased, and T supplementation restored, PDE5 gene expression in rat bladder. Accordingly, bladder strips from castrated rats were more sensitive to SNP-induced relaxation than strips from control or T-replaced rats, whereas in the presence of vardenafil, all groups showed the same SNP sensitivity. To discover whether vardenafil affects bladder activity in vivo, the rat bladder outlet obstruction model was used. Chronic treatment with 10 mg/kg.d vardenafil significantly reduced nonvoiding contractions (47%, P < 0.05 vs. placebo) up to tamsulosin level (51%). Overall, these results demonstrate that PDE5 regulates bladder smooth muscle tone, strongly limiting the nitric oxide/cGMP signaling, and that vardenafil, by blocking PDE5, may be a possible therapeutic option for bladder dysfunction by ameliorating irritative lower urinary tract symptoms.

3',5'-Cyclic-GMP Phosphodiesterases↗

PubMed2006

Natural transmission of USP9Y gene mutations: a new perspective on the role of AZFa genes in male fertility.

Deletions of the azoospermia factor (AZF) regions of the Y chromosome are associated with severe spermatogenic failure and represent the most frequent molecular genetic cause of azoospermia and severe oligozoospermia. The exact role of the candidate AZF genes is largely unknown due to both the extreme rarity of naturally occurring AZF gene-specific mutations and the lack of functional assays. Here, we report the fine characterization of two different deletions in the USP9Y gene (one of the two candidate genes in the AZFa region), which have been transmitted through natural conception in two unrelated families. The associated mild testicular phenotype, in both cases, is in sharp contrast with that of the two previously reported infertile patients bearing a mutation of the same gene. In conclusion, to date, the USP9Y gene has been considered as one of the major Y-linked spermatogenesis genes, based on both its position within the AZFa region and previous reports that correlated USP9Y mutation to severe spermatogenic failure and infertility. This view is now substantially changed because our findings clearly demonstrate that during human spermatogenesis, USP9Y is more likely a fine tuner that improves efficiency, rather than a provider of an essential function. More importantly, the observed natural conceptions suggest that the protein is not required for the final sperm maturation process or for the acquisition of sperm fertilizing ability, providing a new perspective on the role played by the USP9Y gene in male fertility.

Adult↗

PubMed2006

Assessment of the relational factor in male patients consulting for sexual dysfunction: the concept of couple sexual dysfunction.

In a consecutive series of 1140 male subjects reporting a stable couple relationship and different degrees of sexual dysfunction, we evaluated the impact of relational factors, as assessed by the Structured Interview on Erectile Dysfunction (SIEDY) Scale 2 (exploring, as reported by the patient, menopausal symptoms, partner's medical illness interfering with sexual activity, and reduced partner desire and climax). We found that the SIEDY Scale 2 is significantly and independently associated with erectile dysfunction (ED), delayed ejaculation, hypoactive sexual desire, and decreased frequency of intercourse. SIEDY Scale 2 scores are associated with an advanced age of the partner and a long couple relationship, independently from patient's age. In addition, an increased relational factor correlates with increased extramarital affairs, conflicts in the couple, alcohol abuse, and presence of depressive symptoms, as assessed by the Middlesex Hospital Questionnaire. Our results should encourage the andrologist to consider the context in which sexual symptoms develop, analyzing the relationship and partner's behaviors and diseases. Resolving, or at least ameliorating, the relational background and the sexual framework might help in treating male sexual dysfunction.

Erectile Dysfunction↗

PubMed2006

Pathophysiology of sperm motility.

Mammalian spermatozoa acquire the ability to swim during their transit from the testis to the oviduct under the control of several external and intracellular factors. These factors play also a pivotal role in regulating acquisition of hyperactivated motility and during the process of chemotaxis. This review summarizes the involvement of such factors in acquisition and maintenance of sperm motility, hyperactivation and chemotaxis, focusing in particular on the molecular bases of asthenozoospermia, a pathology of seminal plasma characterized by reduced sperm motility, which is one of the main causes of male infertility. Current in vitro treatments of asthenozoospermia are shown, together with the most recent findings on pharmacological and physiological molecules capable of stimulating sperm motility. The structure, function and mechanism of sperm flagellum responsible for the development of active motility are also analyzed in details.

Allergy and Immunology↗

PubMed2006

Origin and biological significance of DNA fragmentation in human spermatozoa.

The occurrence of DNA fragmentation in mammalian spermatozoa was identified in 1993. In human, sperm DNA fragmentation is particularly relevant in subfertile patients (i.e, those subjects more likely to be treated by assisted reproductive techniques). Thus, concerns have been raised about the possibility that sperm with DNA fragmentation may be involved in the process of fertilization, in particular when invasive techniques (such as intracytoplasmatic sperm injection) are applied. Knowledge of the mechanisms responsible for generation of DNA strand breaks may thus help in disclosing and possibly identifying new therapies for the treatment of male infertility. However, the mechanisms involved in generating sperm DNA anomalies are far from being clarified. In this review, we summarize and critically analyze the main current theories that explain generation of DNA fragmentation in spermatozoa: abortive apoptosis (anomalies in apoptosis that occur normally during spermatogenesis), problems in packaging of chromatin (mainly anomalies in histone to protamine substitution) and generation of reactive oxygen species (that may occur at any level during spermatogenesis, sperm maturation and transit in the male genital tract).

Animals↗

PubMed2006

Psychobiologic correlates of the metabolic syndrome and associated sexual dysfunction.

OBJECTIVES: The association of low testosterone level and erectile dysfunction (ED) with metabolic syndrome (MS) is receiving increasing attention. The present study determined the psychobiologic characteristics of sexual dysfunction (SD) associated with MS (as defined by the National Cholesterol Education Program's Adult Treatment Panel III criteria) in a series of 803 consecutive male outpatients. METHODS: Several hormonal, biochemical, and instrumental (penile Doppler ultrasound [PDU]) parameters were studied, along with general psychopathology scores (Middlesex Hospital Questionnaire modified [MHQ]). The Structured Interview on Erectile Dysfunction (SIEDY) was also applied. RESULTS: Among the 236 patients (29.4%) diagnosed as having a MS, 96.5% reported ED, 39.6% hypoactive sexual desire (HSD), 22.7% premature ejaculation, and 4.8% delayed ejaculation. Patients with MS were characterised by greater subjective (as assessed by SIEDY) and objective (as assessed by PDU) ED and by greater somatised anxiety than the rest of the sample. The prevalence of overt hypogonadism (total testosterone <8 nM) was significantly higher in patients with MS. Among MS components, waist circumference and hyperglycaemia were the best predictors of hypogonadism. Hypogonadal patients with MS showed higher gonadotropin and lower free testosterone levels, suggesting a primary hypogonadism. Among patients with MS, hypogonadism was present in 11.9% and 3.8% in the rest of the sample (p<0.0001) and was associated with typical hypogonadism-related symptoms, such as hypoactive sexual desire, low frequency of sexual intercourse, and depressive symptoms. CONCLUSIONS: Our data suggest that MS is associated with a more severe ED and induces somatisation. Furthermore, MS is associated with a higher prevalence of hypogonadism in patients with SD. The presence of hypogonadism can further exacerbate the MS-associated sexual dysfunction, adding the typical hypogonadism-related symptoms (including HSD, 66.7%). Recognising MS associated with hypogonadism is important for both sexual and general health and its serious potential associated risks.

Adult↗

PubMed2006

The vitamin D analogue BXL-628 inhibits growth factor-stimulated proliferation and invasion of DU145 prostate cancer cells.

PURPOSE: Suppression of the invasive phenotype is essential in developing new therapeutic tools to treat advanced prostate cancer (PC) indicating that androgen-independent prostate cancer (AI-PC) is characterized by increased metastatic potential. In the present study, we have investigated the effect of the nonhypercalcemic vitamin D analogue BXL-628 on proliferation and invasive properties of the human PC cell line DU145. In particular, the effect of the analogue was tested following stimulation with a potent growth factor, keratinocyte growth factor (KGF), which stimulates both proliferation and invasion of these cells. We have also evaluated the effect of the analogue on KGF stimulation of PI3K/AKT signaling pathway. METHODS: Cell proliferation was determined by cell counting. Invasion through Matrigel was evaluated using Boyden chambers. PI3K activity was measured by immunokinase assay and AKT phosphorylation was evaluated by western blot analysis. Keratinocyte growth factor receptor (KGFR) autotransphosphorylation was evaluated by western blot after immunoprecipitation of the receptor. RESULTS: BXL-628 is able to inhibit both proliferation and invasion of DU145 cells in basal conditions and in response to KGF. Following stimulation with KGF, the inhibition is due to suppression of KGFR autotransphosphorylation and downstream PI3K/AKT activation, both achieved following a brief (5 min) incubation with the analogue. This effect on KGFR autophosphorylation was still present when cells were treated with the alpha-amanitin, an inhibitor of RNA transcription, indicating a rapid, nongenomic effect. CONCLUSIONS: Our results demonstrate that the vitamin D analogue BXL-628 is able to suppress KGF-induced proliferation and invasion of AI-PC cells in vitro, prospecting a possible use of the drug, which is currently in phase II clinical studies for benign prostatic hyperplasia, in the treatment of advanced prostate cancer.

Calcitriol↗

PubMed2006

Estrogen receptor alpha promoter polymorphism: stronger estrogen action is coupled with lower sperm count.

BACKGROUND: Although the importance of estrogens in male reproduction is indisputable, little attention has been paid to the role of estrogen receptor (ER) gene mutations in male infertility. Significant correlation between (TA)n repeat allelic variants and lumbar bone mineral density was previously observed in the promoter region of the ERalpha gene, indicating that allelic combinations with higher number of (TA)n repeats are functionally more active genetic variants. METHODS: We studied the (TA)n repeat polymorphism situated in the promoter region of the ERalpha gene in a large group of infertile and normospermic men (n = 347). RESULTS: Although the (TA)n polymorphism failed to show a significant association with male infertility, we found a significant effect of this polymorphism on sperm count. In the group of infertile men, the mean TA repeat number and sperm concentration (P = 0.022) and total sperm number (P = 0.043) were inversely correlated, showing an association between higher TA repeat number (genotype A) and lower sperm production. In line with this observation, normospermic subjects with genotype A had a significantly lower mean sperm concentration with respect to men bearing genotype B with shorter TA alleles (P < 0.05) and a lower total sperm count (P < 0.01). CONCLUSIONS: Our data indicate that specific allelic combinations of the ERalpha, which confer a stronger estrogen effect, may negatively influence human spermatogenesis.

Alleles↗

PubMed2006

Sperm cryopreservation in male infertility due to genetic disorders.

Certain chromosomal and genetic anomalies, such as Klinefelter syndrome (47,XXY) and Y chromosome microdeletions, have been reported as potential causes of a progressive impairment of spermatogenesis. In these cases cryoconservation of ejaculated or testicular sperm represent a valuable tool for the preservation of fertility. However, dealing with genetic disorders, the transmission of genetic anomalies has to be taken into consideration. It is therefore important to be aware about the clinical importance and the related genetic risks of these anomalies. In this article we describe the clinical significance of these diseases.

Chromosome Deletion↗

PubMed2006

Testosterone restores diabetes-induced erectile dysfunction and sildenafil responsiveness in two distinct animal models of chemical diabetes.

INTRODUCTION: Hypogonadism is often associated with diabetes and both conditions represent major risk factors for erectile dysfunction (ED). AIM: To investigate the role of hypogonadism on phosphodiesterase type 5 (PDE5) expression and sildenafil responsiveness in diabetes. METHODS: Two different models of experimental diabetes were used: (i) alloxan-induced diabetic rabbit; and (ii) streptozotocin (STZ)-induced diabetic rat. In both experimental models, animals were separated into three groups: control, diabetic, diabetic supplemented with testosterone (T) enanthate. Rabbits were used for "in vitro" experiments. Conversely, each rats group was further subdivided: no further treatment or acute sildenafil dosing (25 mg/kg, 1 hour before "in vivo" electrical stimulation [ES]). MAIN OUTCOME MEASURE: Erectile capacity was evaluated either by "in vitro" contractility study (alloxan-induced diabetic rabbit) and "in vivo" evaluation of erectile response elicited by ES of cavernous nerve (STZ-induced diabetic rats). Also endothelial nitric oxide synthase, neural nitric oxide synthase (nNOS), and PDE5 protein (Western blot) and mRNA (quantitative real-time reverse transcriptase polymerase chain reaction [RT-PCR]) expression were measured in rat penile samples of each group. RESULTS: In both models, hypogonadism was observed, characterized by reduced T and atrophy of androgen-dependent accessory glands. T substitution completely reverted hypogonadism and diabetes-induced penile hyposensitivity to "in vitro" (acetylcholine, rabbit) or "in vivo" (ES, rat) relaxant stimuli, along with nNOS expression, which was reduced (P < 0.05) in STZ rats. In diabetic animals, T substitution reinstated sildenafil-induced enhancement of both "in vitro" nitric oxide donor (NCX 4040) relaxant effect (rabbit) and "in vivo" ES-induced erection (rat). PDE5 was reduced in diabetic STZ rats (P < 0.05) and normalized by T. In STZ rats, sodium nitroprusside (SNP) intracavernous injection induced a more sustained erection than in control rats, which was no further enhanced by sildenafil. T substitution normalized both hyper-responsiveness to SNP and sildenafil efficacy. CONCLUSION: In two models of diabetes T deficiency underlies biochemical alterations leading to ED. Normalizing T in diabetes restores nNOS and PDE5, and reinstates sensitivity to relaxant stimuli and responsiveness to sildenafil.

3',5'-Cyclic-GMP Phosphodiesterases↗

PubMed2006

Effect of chronic tadalafil administration on penile hypoxia induced by cavernous neurotomy in the rat.

BACKGROUND: Numerous men develop postprostatectomy erectile dysfunction (PPED), due to surgery-related nervous damage. PPED is often refractory to phosphodiesterase type 5 (PDE5) inhibitors therapy. AIM: To verify whether chronic tadalafil (CT) preserves bilateral cavernous neurotomy (BCN)-induced penile damage and hypo-oxygenation. METHODS: In a rat model of BCN we evaluated in vitro and ex vivo effect of CT treatment (2 mg/kg, daily for 3 months). RESULTS: Bilateral cavernous neurotomy induced massive hypoxia and decreased muscle/fiber ratio, completely restored by CT. Hypersensitivity of hypoxic tissues to the relaxant effect of the endothelin type B receptor (ETB) agonist IRL-1620 was observed, along with ETB mRNA and protein overexpression. CT restored sensitivity to IRL-1620, and normalized ETB expression. Hypoxic penis showed increased sensitivity to the relaxant effect of the nitric oxide donor sodium nitroprusside (SNP), while acute tadalafil (100 nM) did not amplify the SNP effect. Accordingly, PDE5 mRNA and protein were reduced in BCN penile tissues. By restoring PDE5, CT decreased SNP-induced relaxation and rescued sensitivity to acute tadalafil. However, in hypoxic penis, CT normalizes neither acetylcholine hyporesponsiveness nor neuronal nitric oxide synthase-endothelial nitric oxide synthase expression. CONCLUSION: Chronic tadalafil restores some of the investigated BCN-induced alterations, including PDE5 and tadalafil efficacy.

Animals↗

PubMed2006

ANDROTEST: a structured interview for the screening of hypogonadism in patients with sexual dysfunction.

INTRODUCTION: Detecting hypogonadism, which is important in the general population, becomes crucial in patients with sexual dysfunctions, because hypogonadism can have a causal role for them and testosterone (T) substitution represents a milestone for the therapy. AIM: No inventories are available for the screening of hypogonadism in patients with sexual dysfunction. We wished to set up a brief structured interview providing scores useful for detecting hypogonadism defined as low total T (<10.4 nmol/L, 300 ng/dL) in a symptomatic population (sexual dysfunction). METHODS: A minimum set of items was identified within a larger structured interview through iterative receiver-operating characteristic curve analysis, with assessment of sensitivity and specificity for hypogonadism in a sample of 215 patients. MAIN OUTCOME MEASURES: Sensitivity and specificity were verified in a further sample of 664 patients. Correlation of test scores with prostate-specific antigen (PSA), testis volume, and others clinical and psychological parameters, was assessed for concurrent validity. RESULTS: In the validation sample, the final 12-item version of the interview (ANDROTEST) had a sensitivity and specificity of 68% and 65%, in detecting low total T (<10.4 nmol/L) and of 71% and 65%, in the screening for low free T (<37 pmol/L). Furthermore, patients with a pathological test (i.e., score >8) showed higher prevalence of hypogonadism-related signs, such as lower testis volume and higher depressive symptoms. Finally, when only younger patients (<54 years, which represents the median age of the sample) were considered, Log10 [PSA] levels were significantly lower in those with ANDROTEST score >8. CONCLUSION: ANDROTEST is a quick and easy-to-administer interview that provides scores for the screening of male hypogonadism in patients with sexual dysfunction.

Adult↗

PubMed2005

The androgen receptor and prostate cancer invasion.

Recent evidence indicates that androgen-sensitive prostate cancer cells are characterized by a less pronounced malignant phenotype. We demonstrate that transfection with an androgen receptor (AR) expression vector of the androgen-independent (AI) prostate cancer cell line PC3 decreases invasion and adhesion of these cells through modulation of alpha6beta4 integrin expression. Treatment of PC3-AR cells with the synthetic androgen R1881 further reduced invasion without modifying alpha6beta4 expression on the cell surface, suggesting interference with the invasion process in response to EGF by an alternative mechanism. We investigated EGF-induced auto-transphosphorylation of EGFR in both cell lines. We found that EGFR auto-transphosphorylation was reduced in PC3-AR cells and was further decreased by administration of androgens. Since auto-transphosphorylation regulates many different functions of EGFR, including docking of kinases, ubiquitination and internalization, we next investigated all these processes in PC3-AR cells. EGF-stimulated PI3K activity, a key signalling pathway for invasion of these cells, was decreased in PC3-AR cells and further reduced by treatment with R1881. Interestingly, EGFR-PI3K interaction was also disrupted in these cells. Furthermore, EGFR ubiquitination and internalization were found to be reduced in PC3-AR cells both in basal conditions and following treatment with androgens. According to recent findings, an endocytotic pathway may be important for EGFR signalling by controlling the specificity of the response. By using immunoconfocal fluorescent microscopy, we demonstrated that AR in PC3 cells is mainly located in cytoplasm and transmigrates in part to the nucleus following stimulation with androgens. Interestingly, immunoconfocal and immunoprecipitation experiments demonstrated also the occurrence of co-localization and interaction of AR with EGFR in PC3-AR cells and in another androgen-dependent PC cell line, LNCaP. We hypothesize a mechanism by which, through direct interaction with EGFR, the AR elicits a reduction of EGF-mediated signalling and confers a less malignant phenotype.

Active Transport, Cell Nucleus↗

PubMed2005

Psychobiological correlates of delayed ejaculation in male patients with sexual dysfunctions.

The pathogenesis of delayed ejaculation (DE) is rather unknown, though the contribution of various psychological, marital, hormonal, and neurological factors has been advocated. In this study we systematically investigated the relative relevance of the aforementioned factors in 1,632 men who were seeking medical help for sexual dysfunction. The severity of DE was classified according to Kaplan criteria. Mild and moderate forms of DE (MMDE) recognized different risk factors than the most severe ones (anejaculation or severe DE [ASDE]). ASDE was essentially coupled with the presence of neurological diseases or with the use of serotoninergic drugs. Serotoninergic drugs also significantly increase (by at least 10-fold) the risk for MMDE, which, however, was also coupled with other relational factors (eg, partner's impaired climax, patient's hypoactive sexual desire [HSD]) or intrapsychic factors (eg, stress at work). At multiple regression analysis, some organic pathological conditions (such as psychiatric disorders and hypogonadism) were also associated with MMDE. In particular, hypogonadism retained significance for DE even after adjustment for HSD (adjusted odds ratio = 2.08 [1.11-3.89]; P < .05), suggesting other effects of testosterone deficiency on the ejaculatory reflex besides reduced libido. In conclusion, the present study demonstrates that multiple psychobiological determinants are associated with DE, a still obscure condition that substantially impairs psychosexual equilibrium of the couple.

Ejaculation↗

PubMed2005

Non-genomic effects of the androgen receptor and vitamin D agonist are involved in suppressing invasive phenotype of prostate cancer cells.

Suppression of invasive phenotype is essential in developing new therapeutic tools to treat prostate cancer (PC). Evidence indicates that androgen-dependent (AD) prostate cancer cells are characterized by a lower malignant phenotype. We have demonstrated that transfection with an androgen receptor (AR) expression vector of the androgen-independent (AI) prostate cancer cell line PC3 decreases invasion of these cells through modulation of alpha6beta4 integrin expression, indicating a genotropic effect of androgens in inhibiting invasion ability of AD PC cells. Later on, we have shown that also a non-genotropic mechanism is involved in such an effect. By using immunoconfocal fluorescent microscopy, we demonstrated that AR in PC3-AR cells co-localizes with the EGFR receptors (EGFR) in PC3-AR cells. Co-immunoprecipitation studies both in PC3-AR cells and in the AD cell line LNCaP that physiologically express both receptors, confirm the occurrence of an interaction between of the two proteins. In PC3-AR cells, we demonstrated a disruption of EGFR signalling properties (reduced EGF-induced EGFR autotransphosphorylation, reduced EGF-stimulated PI3K activity as well as EGFR-PI3K interaction) contributing to the lower invasive phenotype of these cells. In another study, we investigated the effects of a new Vitamin D analogue, BXL628, on invasion in response to KGF in the androgen-independent PC cell line DU145. We found that the compound was able to reduce proliferation and invasion of the cells in response to the growth factor. In addition, we found that KGF-induced autotransphosphorylation of KGF receptor (KGFR) and PI3K activation were suppressed after short-term (5min) pre-treatment with the analogue before addition of KGF. Collectively, these studies demonstrate that a non-genotropic effect due to a direct interaction of the androgen receptor with EGFR and to a rapid effect of a Vitamin D agonist on KGFR may disrupt signalling of GF leading to decreased tumorigenicity and a less malignant phenotype of PC cells in vitro.

Antineoplastic Agents↗

PubMed2005

Enhancement of mouse sperm motility by the PI3-kinase inhibitor LY294002 does not result in toxic effects on preimplantation embryo development.

BACKGROUND: A reduced number of progressively motile sperm (as may occur in cases of asthenozoospermia or when cryopreserved spermatozoa are used for fertilization) limits the possibility of applying various assisted reproductive techniques (ARTs). We previously showed that incubation of sperm with the phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 increases sperm progressive motility and enhances the number of sperm recovered by capacitation protocols used in ART. METHODS AND RESULTS: In the present study, we investigate the motility-enhancing effects of this compound in epididymal mouse sperm, and examine the use of the mouse system to investigate the effect of LY294002 on oocyte fertilization and preimplantation embryo development. Our results show that neither pre-incubation of mouse spermatozoa with the inhibitor during in vitro capacitation nor the direct addition of LY294002 to the sperm-oocyte mixture significantly affects the process of fertilization and preimplantation development of embryos produced even when they developed in the presence of LY294002. CONCLUSIONS: The present data encourage the design of new drugs based on the molecular structure of LY294002, which may open up new options for the in vitro treatment of human/animal asthenozoospermia.

Animals↗

PubMed2005

Oxytocin mediates the estrogen-dependent contractile activity of endothelin-1 in human and rabbit epididymis.

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.

Animals↗

PubMed2005

Sperm ubiquitination positively correlates to normal morphology in human semen.

BACKGROUND: Global ubiquitination in human semen has been found to negatively correlate with standard semen parameters, indicating that ubiquitination can be considered a marker of poor semen quality. However, the inclusion of all semen components in the analysis may be misleading on the biological significance of ubiquitination of sperm cells. We have recently demonstrated the variable presence of bodies of different size, with the highest concentration in oligoasthenoteratozoospermia. The purpose of the present study was to evaluate the relationship between ubiquitination and standard semen parameters, after distinguishing between ubiquitinated sperm and bodies in each sample. METHODS: Ubiquitination was evaluated by flow cytometric sperm ubiquitin tag immunoassay (SUTI) in sperm samples from 45 subjects. Semen analysis was performed according to WHO (1999) guidelines. RESULTS: When only ubiquitinated sperm were considered, a positive correlation with number, motility and normal morphology was found. When correlation was evaluated considering the percentage of ubiquitinated bodies, a negative correlation was found with good semen quality. CONCLUSIONS: Results indicate that the negative correlations previously found between global semen ubiquitination and parameters of semen analysis are mainly driven by components other than sperm. The positive correlation between sperm ubiquitination and good quality parameters suggests a previously unrecognized role for sperm ubiquitination.

Biomarkers↗