Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Sperm Capacitation”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed2002

[Advances in sperm capacitation].

Sperm must be capacitated before sperm-ovum fusion. Capacitation was once considered as hyperactivation. But now many investigators thought that capacitation wasn't equal to hyperactivation, and that sperm hyperactivation might be a moiety of capacitation or the result of capacitation. In the present, the methods used to study sperm capacitation include fertilization in vitro, induction of sperm acrosome reaction, FITC-labeled chlortetracycline and plant hemoagglutinin. The studies on sperm capacitation in vitro mainly focused on the inductive substances of sperm capacitation and subsequent results analysis. It could lay foundation for the manifestation of molecular mechanism of sperm capacitation and destination of sperm capacitation in molecular levels.

Adenylyl Cyclases↗
PubMed2004

Tyrosine phosphorylation generates multiple isoforms of the mitochondrial capsule protein, phospholipid hydroperoxide glutathione peroxidase (PHGPx), during hamster sperm capacitation.

Sperm capacitation is a maturation process, occurring in the female reproductive tract, that produces fertilization-competent spermatozoa. Protein tyrosine phosphorylation represents an important event in capacitation. The present study demonstrates the capacitation-dependent tyrosine-phosphorylation of phospholipid hydroperoxide glutathione peroxidase (PHGPx), the disulfide cross-linked, major structural protein of the sperm mitochondrial capsule. Immunofluorescence microscopy using an antiphosphotyrosine monoclonal antibody (anti-pY20) demonstrated the presence of capacitation-associated tyrosine phosphorylated proteins in the flagellum of hamster spermatozoa. Among the tyrosine-phosphorylated polypeptides (M(r) 19,000- 99,000), a 19-kDa polypeptide was the only one that can be solubilized completely by Triton X-100-dithiothreitol (DTT). The 19-kDa polypeptide was purified by anion-exchange chromatography and by immunoaffinity chromatography. Proteomic identification of the 19-kDa polypeptide by nano-electrospray tandem mass spectrometry yielded six peptides that matched the National Center for Biotechnology Information (NCBI) database sequences of bovine PHGPx. Indirect immunofluorescence localized PHGPx to the midpiece of the flagellum and the immunoblot analysis demonstrated its DTT-dependent release from purified flagella. DTT extracts of noncapacitated spermatozoa exhibited a charge train of four major PHGPx isoforms (pIs 7.5- 9.0) by two-dimensional PAGE, whereas capacitated spermatozoa revealed the generation of new acidic PHGPx isoforms with isoelectric points ranging between pH 6.0-7.0 and 4.0-5.0, indicating that it is posttranslationally modified during capacitation. These data suggest that the tyrosine-phosphorylation of PHGPx may represent an important event in the signaling pathway(s) associated with capacitation and could potentially affect mitochondrial function.

Amino Acid Sequence↗
PubMedDate not supplied

Influence of bovine follicular and oviduct fluids on sperm capacitation in vitro.

The ability of bovine follicular fluid (FF) and oviduct fluid (ODF) to capacitate sperm was determined. At concentrations of greater than 20%, both FF and ODF capacitated sperm within 4 hours, but at concentrations greater than 40%, FF also initiated the acrosome reaction. Non-luteal ODF at a concentration greater than 60% capacitated sperm within 2 hours. Non-luteal ODF maintained sperm motility better than either luteal ODF or FF. Sperm previously capacitated in ODF underwent the acrosome reaction when exposed to solubilized zonae pellucidae (25 ng/microL) or FF (20%, V/V). Sperm treated with 60% non-luteal ODF or 60% FF fertilized more oocytes at 2 hours than did sperm in treatments with less concentrated fluid. After 4 hours, all fluid treatments and modified Tyrode's medium supplemented with heparin exhibited a higher percentage of fertilized oocytes than the modified Tyrode's medium alone. Concentrations of both protein and glycosaminoglycans were significantly lower in ODF than in either blood serum or FF. These studies demonstrated that ODF capacitated sperm and sustained motility, but sperm were capacitated more rapidly in non-luteal than in luteal ODF. In contrast, FF was able to both capacitate sperm and induce the acrosome reaction. These effects of ODF and FF on aspects of sperm function were uniquely concentration-dependent, suggesting that different mechanisms may operate in ODF and FF to regulate these events.

Acrosome↗
PubMed1996

Membrane lipid dynamics during human sperm capacitation.

Sperm membranes have an unusual lipidic composition which is distinct from those of mammalian somatic cells. They have high levels of plasmalogens, a kind of ether-linked lipids, and a high content of polyunsaturated fatty acyl groups. Plasmalogens may form non-diffusible membrane regions or domains, whereas polyunsaturated ethanolamine plasmalogens are known to destabilize the lipidic bilayer. During transit of sperm through the female reproductive tract, sperm-coating proteins bind to heparin-like glycosaminoglycans. An essential feature of capacitation is the removal of cholesterol from the acrosomal membrane of sperm. Albumin and high-density lipoproteins present in the uterine and follicular fluid act as cholesterol acceptors. Plasma membrane of sperm organize in large non-diffusible lipid domains. This regionalization affects the distribution of both lipids and proteins. A barrier to lateral diffusion of lipids and proteins in the equatorial segment has been reported and contributes to the formation of macrodomains. Lateral separation into cholesterol-rich and cholesterol-depleted microdomains could also be created. Cone-shaped phospholipids induce the formation of non-bilayer phases and might facilitate membrane fusion. This review will discuss the removal of coating proteins, cholesterol efflux, domain organization, relocalization of lipids and proteins and the role of fusogenic lipids during capacitation.

Acrosome↗
PubMed1985

The effect of in vitro sperm capacitation on sperm velocity and motility as measured by an in-office, integrated, microcomputerized system for semen analysis.

The authors measured the effects of in vitro washing and capacitation on sperm velocity and motility on one hundred males, using an in-office, integrated, microcomputerized system for objective semen analysis. Sperm characteristics, including sperm velocity, percentage of motile sperm, and the motility index improved significantly following the washing procedure. Average sperm velocity increased from 19.9 microns per second in the original specimens to 26.3 mic/sec following washing (P less than 0.05), while percentage of motile sperm and the sperm motility index (MI) increased from 30% to 86% (P less than 0.01) and 6.6 to 22.5 (P less than 0.01) respectively. The most significant differences occurred in the asthenospermic subgroup, with sperm velocity increasing from 16.3 microns per second to 24.6 mic/sec (P less than .001), percentage motility increasing from 15% motility to 85% motility (P less than 0.001), and the motility index (MI) increasing from 2.4 to 21.6 (P less than 0.001). The advantage of a widely acceptable method for quantitative evaluation of semen quality is discussed.

Adult↗
PubMed2006

Sperm capacitation is regulated by the crosstalk between protein kinase A and C.

The binding of capacitated sperm to the egg's zona pellucida stimulates it to undergo the acrosome reaction, a process which enables the sperm to penetrate the egg. Mammalian sperm capacitation and the acrosome reaction require remodeling of actin filaments. An increase in phospholipase D (PLD)-dependent actin polymerization occurs during capacitation whereas the increase in sperm intracellular calcium after its binding to the egg causes very fast actin depolymerization prior to the acrosome reaction. Protein kinase A (PKA) and C (PKC) can both activate sperm PLD and actin polymerization under in vitro incubation, however under physiological conditions, actin polymerization depends primarily on PKA activity. We suggest that PKA indirectly activates phosphatidylinositol 4-kinase to produce phosphatidylinositol 4,5-bisphosphate which is a cofactor for PLD activation. In addition, activation of PKA during capacitation inactivates phospholipase C resulting in preventing PKC activation. It appears that PKA activation promotes sperm capacitation whereas too early activation of PKC during capacitation would jeopardize this process. Thus, a refined balance between the two pathways is required for optimal and sustained activation during sperm capacitation.

Animals↗
PubMed1987

Use of salt-stored zonae pellucidae for assessing rabbit sperm capacitation for in vitro fertilization.

Zonae pellucidae of tubal and follicular oocytes were collected and prepared for salt storage. Cumulus and corona radiata cells were removed from oocytes with hyaluronidase and a small bore pipette. The oocytes (referred to as zonae since vitelline were rendered nonfunctional) were stored in a salt solution at 4 degrees C. Using in utero capacitated sperm, the penetrability of zonae from tubal and follicular oocytes stored immediately after collection was compared to controls, i.e., in vitro development of tubal ova to the 4-cell stage within 24 hr. The penetration rates were 100% (8 penetrated/8 inseminated), 77.8% (7 penetrated/9 inseminated), and 100% (10 fertilized/10 inseminated), respectively, and these were not statistically different. The mean (x) numbers of sperm able to penetrate the zonae, into the perivitelline space (PVS) for tubal (34.0) and follicular (1.1) oocytes were significantly different (P less than 0.01). However, following maturational incubation before salt storage, zonae of tubal and follicular origin showed no significant differences in penetrability of in utero capacitated sperm when assessed by percent penetration, or mean numbers of sperm cells reaching the PVS: tubal zonae, 100% (15/15), and follicular zonae, 100% (18/18), and mean number of sperm in the PVS (x [tubal zonae] = 12.4, and x [follicular zonae] = 11.8). The penetrability of tubal zonae with and without maturational incubation was compared, and no significant differences in penetrability by in utero capacitated sperm were present when assessed by percent penetration nonmatured 92.6% (25/27) and matured 93.3% (28/30) and mean number of sperm in the PVS (x [nonmatured] = 3.33 and x [matured] = 2.41). In vitro capacitation of ejaculated rabbit sperm by serum treatment was assessed by the penetration of salt-stored zonae, zona-free hamster oocytes (ZFHO), and in vitro fertilization of freshly collected tubal oocytes. None of 60 salt-stored zonae and none of 31 tubal oocytes were penetrated, and these values were significantly (P less than 0.005) smaller than the 9 of 78 (12%) zona-free hamster ova that were penetrated by sperm cells from the same sample. In vitro capacitation of ejaculated rabbit sperm by washing and preincubation was assessed by the penetration of salt-stored zonae, zona-free hamster oocytes (ZFHO), and fertilization of freshly collected tubal oocytes. Seventy-six of 80 salt-stored zonae were penetrated, and this was significantly (P less than 0.005) greater than the 67 of 87 tubal oocytes fertilized and 30 of 35 ZFHO penetrated, which were not significantly different.(ABSTRACT TRUNCATED AT 400 WORDS)

Ammonium Sulfate↗
PubMedDate not supplied

In vitro sperm capacitation and intrauterine insemination (IVC-Insem): a simple technique for the treatment of refractory infertility unrelated to female organic pelvic disease. Clinical results and immunological effects: a preliminary report.

12 couples, with infertility due to male subfertility, female antisperm isoimmunization, male antisperm autoimmunization, cervical mucus insufficiency or unexplained infertility underwent intrauterine A.I.H. with capacitated sperm and controlled ovarian stimulation. The pregnancy percentage was of 41.6% per woman treated and of 31.2% per treatment cycle; five pregnancies were obtained, of which two resulted in abortions. Five cases of oligoasthenospermia were treated, three severe and two moderate; two pregnancies occurred in the former and one in the latter. S.I.T. and S.I.T.-cap. were performed on the serum, and Micro-S.I.T. and Micro-S.I.T.-cap. on the cervical mucus in order to exclude the possibility that intrauterine A.I.H. with capacitated sperm might have caused capacitated or non-capacitated antisperm immunization. Intrauterine A.I.H. would seem to be a useful alternative to G.I.F.T. and to I.V.F./E.T. or at least a technique which should be performed before these two in cases of infertility not caused by female organic pelvic disease; it is cheap, simple and extremely well-accepted by the patient.

Adult↗
PubMed1996

Effects of oocyte maturation length, sperm capacitation time, and heparin on bovine embryo development.

This study examined the effects of extending oocyte maturation 4 h beyond current methods and capacitating sperm with or without heparin 4 h before oocyte introduction to determine whether embryo development would increase after in vitro fertilization. Oocytes were aspirated from ovaries that were collected at slaughter. Cumulus-enclosed oocytes were matured in M-199 supplemented with serum from cows in standing estrus (20%), antibiotic-antimycotic solution (1%), HEPES (10 mM), and equine LH (30 micrograms/ml) in a humidified 5% CO2 atmosphere. Oocytes were matured for either 24 or 28 h and subsequently fertilized with sperm that had been capacitated 0 or 4 h (before oocyte contact) with or without heparin (0.2 microgram/ml). Data were analyzed as a 2 x 2 x 2 factorial design. Percentages of cleavage and development were transformed by the arcsin square root method before analysis of variance. An interaction of maturation length and sperm capacitation resulted because cleavage rate decreased with precapacitated sperm, but only within the 24-h maturation period. Heparin increased cleavage rate at 48 h after fertilization but did not affect further development. More oocytes developed to morulae when they matured for 24 h than when they matured for 28 h. In conclusion, a 24-h maturation length without precapacitated sperm was optimal for the subsequent development of cumulus-oocyte complexes.

Animals↗
PubMed2005

Role of actin cytoskeleton in mammalian sperm capacitation and the acrosome reaction.

In order to fertilize, the mammalian spermatozoa should reside in the female reproductive tract for several hours, during which they undergo a series of biochemical modifications collectively called capacitation. Only capacitated sperm can undergo the acrosome reaction after binding to the egg zona pellucida, a process which enables sperm to penetrate into the egg and fertilize it. Polymerization of globular (G)-actin to filamentous (F)-actin occurs during capacitation, depending on protein kinase A activation, protein tyrosine phosphorylation, and phospholipase D activation. F-actin formation is important for the translocation of phospholipase C from the cytosol to the sperm plasma membrane during capacitation. Prior to the occurrence of the acrosome reaction, the F-actin should undergo depolymerization, a necessary process which enables the outer acrosomal membrane and the overlying plasma membrane to come into close proximity and fuse. The binding of the capacitated sperm to the zona pellucida induces a fast increase in sperm intracellular calcium, activation of actin severing proteins which break down the actin fibers, and allows the acrosome reaction to take place.

Acrosome Reaction↗
PubMed1997

Localization of a 25 kDa human sperm surface protein: its role in in-vitro human sperm capacitation.

A human endometrial sialic acid-binding glycoprotein (SABP) binds specifically to a 25 kDa protein on the plasma membranes of human non-capacitated sperm heads. In-vitro labelling of the sperm surface sialoglycoconjugates and subsequent incubation with SABP, suggests removal of some sialoglycoconjugate moieties from the sperm surface upon interaction with SABP. SABP also induces the exposure of mannose ligand receptors on the sperm surface and increases the production of superoxide anion (O2-).

Binding Sites↗
PubMed2007

Suppression effect of seminal vesicle autoantigen on platelet-activating factor-induced mouse sperm capacitation.

Mammalian sperm gain the ability to fertilize an egg successfully by the capacitation process. An unregulated capacitation process causes sperm to undergo a spontaneous acrosome reaction (AR) and resulting in loss of their fertilization activity. Thus, functional sperm activation is tightly regulated by a capacitation and suppression (decapacitation) mechanism. Factors, such as platelet-activating factor (PAF) present in both sperm and the female genital tract, are able to stimulate sperm capacitation. Seminal plasma is thought to have the ability to suppress sperm capacitation; however, the regulatory mechanisms of seminal plasma protein on sperm capacitation are not well understood. Recently, we demonstrated that seminal vesicle autoantigen (SVA), a major seminal vesicle secretory protein, is able to suppress mouse sperm capacitation. To further study the suppression spectra of SVA on sperm capacitation, we investigated the effect of SVA on PAF-induced mouse sperm capacitation-related signals. Here, we demonstrate that SVA decreases the [Ca(2+)](i) to suppress the PAF's effects on [Ca(2+)](i), the cAMP level, protein tyrosine phosphorylation, and capacitation. The inhibition of PAF-induced protein tyrosine phosphorylation and capacitation by SVA can be reversed by cAMP agonists. Characterization of the interactions of SVA with PAF by TLC overlay and tryptophan fluorescence spectrum analyses indicates that SVA is capable of binding PAF with an apparent dissociation constant K(d) > 50 microM. Together with these results, we demonstrate that SVA deceases [Ca(2+)](i) and cross-talks with PAF-induced intracellular signals to regulate mouse sperm capacitation.

Animals↗
PubMed2002

Involvement of a Na+/HCO-3 cotransporter in mouse sperm capacitation.

Mammalian sperm are incapable of fertilizing eggs immediately after ejaculation; they acquire fertilization capacity after residing in the female tract for a finite period of time. The physiological changes sperm undergo in the female reproductive tract that render sperm able to fertilize constitute the phenomenon of "sperm capacitation." We have demonstrated that capacitation is associated with an increase in the tyrosine phosphorylation of a subset of proteins and that these events are regulated by an HCO(3)(-)/cAMP-dependent pathway involving protein kinase A. Capacitation is also accompanied by hyperpolarization of the sperm plasma membrane. Here we present evidence that, in addition to its role in the regulation of adenylyl cyclase, HCO(3)(-) has a role in the regulation of plasma membrane potential in mouse sperm. Addition of HCO(3)(-) but not Cl(-) induces a hyperpolarizing current in mouse sperm plasma membranes. This HCO(3)(-)-dependent hyperpolarization was not observed when Na(+) was replaced by the non-permeant cation choline(+). Replacement of Na(+) by choline(+) also inhibited the capacitation-associated increase in protein tyrosine phosphorylation as well as the zona pellucida-induced acrosome reaction. The lack of an increase in protein tyrosine phosphorylation was overcome by the presence of cAMP agonists in the incubation medium. The lack of a hyperpolarizing HCO(3)(-) current and the inhibition of the capacitation-dependent increase in protein tyrosine phosphorylation in the absence of Na(+) suggest that a Na(+)/HCO(3)(-) cotransporter is present in mouse sperm and is coupled to events regulating capacitation.

Acrosome Reaction↗
PubMed1995

Comparison of bovine sperm capacitation systems for ability of sperm to penetrate zona-free hamster oocytes and bovine oocytes matured in vitro.

Sperm from the same ejaculate were capacitated in calcium-free Tyrode's, modified Tyrode's with bovine follicular fluid or heparin, and TEST-yolk. Capacitated sperm were coincubated with zona-free hamster oocytes at 37 degrees C for 3 h or with bovine cumulus-enclosed oocytes matured in vitro for 8 h at 37 or 39 degrees C. Bovine oocytes were transferred to fertilization medium and incubated for 72 h at 37 or 39 degrees C. Penetration of zona-free hamster oocytes was highest in calcium-free Tyrode's (53.7%), followed by Tyrode's with follicular fluid (50.6%), TEST-yolk (48.6%), and Tyrode's with heparin (34.2%). Penetration of bovine cumulus-enclosed oocytes matured in vitro at 37 degrees C was highest with heparin (48.1%), followed by TEST-yolk (35.0%), calcium-free Tyrode's (32.5%), and follicular fluid (26.4%). Sperm capacitation with heparin, assayed by penetration of bovine oocytes at 39 degrees C, was better at 39 degrees C (77.1%) than at 37 degrees C (46.1%). However, penetration rates in calcium-free Tyrode's and TEST-yolk were higher at 37 degrees C. The capacitation system with heparin at 39 degrees C and bovine oocytes was best followed by the systems using TEST-yolk and calcium-free Tyrode's at 37 degrees C.

Animals↗
PubMed2005

Isolation and characterization of glycosaminoglycans from bovine follicular fluid and their effect on sperm capacitation.

The majority of published studies have reported the use of commercial heparin to capacitate bovine sperm. However, heparin is not present in the female genital tract fluids. In this study, we purified large amounts of glycosaminoglycans (GAGs) from bovine follicular fluid (FF), characterized them and determined their potential to capacitate sperm. FF-GAGs were isolated by protease digestion, lipid extraction, and by different precipitation conditions and then purified by ion exchange chromatography. Two GAGs, heparan sulfate and chondroitin sulfate B, were present in FF. To determine the capacitation potential of FF-GAGs, bovine ejaculated sperm were incubated 5 hr with or without 12 or 24 microg/ml of each of the FF-GAG fractions or with heparin (12 microg/ml). The purified FF-GAGs and heparin did not stimulate sperm acrosome reaction (AR), but stimulated sperm capacitation. Fractions 1 and 2 (heparan sulfate) were more active to promote capacitation (stimulated up to 3.2-fold) than fractions 3 and 4 (mostly chondroitin sulfate B). Fractions 3 and 4 stimulated capacitation two times more than the control (without FF-GAGs or heparin). When the heparan sulfate impurity was removed from fractions 3 and 4 by acid hydrolysis, the capacitation-promoting activity associated with these fractions did not change significantly. When 24 microg/ml of fraction 1 or 2 were used, the percentage of sperm capacitation observed was similar to the capacitation with 12 microg/ml of heparin. Our results also indicated that the FF-GAGs interact strongly with the BSP proteins. Therefore, it is concluded that heparan sulfate is the GAG that is the most potent capacitating factor present in bovine FF.

Acrosome Reaction↗
PubMed2006

Signal transduction mechanisms involved in in vitro ram sperm capacitation.

We validate the chlortetracycline (CTC) technique for the evaluation of capacitation and acrosome reaction-like changes in ram sperm, carrying out a double estimation of the acrosome status after treatment with lysophosphatidylcholine, using fluorescein isocyanate (FITC)-RCA/ethidium homodimer 1 (EthD-1) and CTC/EthD-1. Highly consistent results and a positive correlation between the results of acrosome-reacted sperm evaluated with both techniques were obtained. In this study, we evaluate the effects of ram sperm capacitation of BSA, Ca(2+), NaHCO(3) and cAMP agonists and their influence on the associated protein tyrosine phosphorylation. We found a time-dependent increase in capacitation related to protein tyrosine phosphorylation, either in the absence or the presence of BSA. The addition of an increasing concentration of cholesterol to samples containing BSA did not influence results. The effect of bicarbonate was concentration-dependent, with a significantly lowered value of non-capacitated sperm in the presence 18 and 25 mM. The addition of extracellular calcium did not significantly increase either the proportion of capacitated sperm or the protein tyrosine phosphorylation signalling, although a significantly higher value of acrosome-reacted sperm was found in samples containing 4 mM Ca(2+). cAMP agonists increased capacitated sperm and protein tyrosine phosphorylation signalling. The inhibition of protein kinase A by H-89 caused a decrease in sperm capacitation. Addition of a calcium-entry blocker (Verapamil; Sigma) did not influence results, which suggests that the calcium entry blocker was unable to inhibit the calcium influx associated with capacitation in ram sperm. Our findings might benefit our understanding of the biochemical mechanisms involved in mammalian sperm capacitation and ultimately, fertility.

Acrosome Reaction↗