The acrosome reaction is a prerequisite for fertilization, and its signaling pathway has been investigated for decades. Regardless of the type of inducers present, the acrosome reaction is ultimately mediated by the elevation of cytosolic calcium. Inositol 1,4,5-trisphosphate-gated calcium channels are important components of the acrosome reaction signaling pathway and have been confirmed by several researchers. In this study, we used a novel permeabilization tool BioPORTER^® and first demonstrated its effectiveness in spermatozoa. The inositol 1,4,5-trisphosphate type-1 receptor antibody was introduced into spermatozoa by BioPORTER^® and significantly reduced the calcium influx and acrosome reaction induced by progesterone, solubilized zona pellucida, and the calcium ionophore A23187. This finding indicates that the inositol 1,4,5-trisphosphate type-1 receptor antibody is a valid inositol 1,4,5-trisphosphate receptor inhibitor and provides evidence of inositol 1,4,5-trisphosphate-gated calcium channel involvement in the acrosome reaction in human spermatozoa. Moreover, we demonstrated that the transfer of 1,4,5-trisphosphate into spermatozoa induced acrosome reactions, which provides more reliable evidence for this process. In addition, by treating the spermatozoa with inositol 1,4,5-trisphosphate/BioPORTER^® in the presence or absence of calcium in the culture medium, we showed that the opening of inositol 1,4,5-trisphosphate-gated calcium channels led to extracellular calcium influx. This particular extracellular calcium influx may be the major process of the final step of the acrosome reaction signaling pathway.
Acrosome Reaction/physiology* ; Calcimycin/pharmacology* ; Calcium/pharmacology* ; Calcium Ionophores/pharmacology* ; Drug Delivery Systems ; Humans ; Inositol 1,4,5-Trisphosphate Receptors/metabolism* ; Male ; Progesterone/pharmacology* ; Spermatozoa/metabolism* ; Zona Pellucida/metabolism*

The evaluation of infertility in males consists of physical examination and semen analyses. Standardized semen analyses depend on the descriptive analysis of sperm motility, morphology, and concentration, with a threshold level that must be surpassed to be considered a fertile spermatozoon. Nonetheless, these conventional parameters are not satisfactory for clinicians since 25% of infertility cases worldwide remain unexplained. Therefore, newer tests methods have been established to investigate sperm physiology and functions by monitoring characteristics such as motility, capacitation, the acrosome reaction, reactive oxygen species, sperm DNA damage, chromatin structure, zona pellucida binding, and sperm-oocyte fusion. After the introduction of intracytoplasmic sperm injection technique, sperm maturity, morphology, and aneuploidy conditions have gotten more attention for investigating unexplained male infertility. In the present article, recent advancements in research regarding the utilization of male fertility prediction tests and their role and accuracy are reviewed.
Acrosome Reaction ; Aneuploidy ; Chromatin ; DNA Damage ; Fertility* ; Humans ; Infertility ; Infertility, Male ; Male* ; Physical Examination ; Physiology ; Reactive Oxygen Species ; Semen Analysis ; Sperm Injections, Intracytoplasmic ; Sperm Motility ; Spermatozoa ; Zona Pellucida

Fertilization is a process involving multiple steps that lead to the final fusion of one sperm and the oocyte to form the zygote. One of the steps, acrosome reaction (AR), is an exocytosis process, during which the outer acrosome membrane fuses with the inner sperm membrane, leading to the release of acrosome enzymes that facilitate sperm penetration of the egg investments. Though AR has been investigated for decades, the initial steps of AR in vivo, however, remain largely unknown. A well elucidated model holds the view that AR occurs on the surface of the zona pellucida (ZP), which is triggered by binding of sperm with one of the ZP glycosylated protein, ZP3. However, this model fails to explain the large number of 'falsely' acrosome-reacted sperms found within the cumulus layer in many species examined. With the emerging evidence of cross-talk between sperm and cumulus cells, the potential significance of AR in the cumulus oophorus, the outer layer of the egg, has been gradually revealed. Here we review the acrosome status within the cumulus layer, the cross-talk between sperm and cumulus cells with the involvement of a novel sperm-released factor, NYD-SP8, and re-evaluate the importance and physiological significance of the AR in the cumulus in fertilization.
Acrosome Reaction ; physiology ; Cell Communication ; Cumulus Cells ; metabolism ; Female ; Fertilization ; physiology ; Humans ; Male ; Membrane Proteins ; metabolism ; Oocytes ; metabolism ; Progesterone ; physiology ; Spermatozoa ; metabolism

OBJECTIVE: To investigate the relationship between sperm acrosome reaction (AR) and the clinical pregnancy rate of intrauterine insemination (IUI). METHODS: We detected the sperm spontaneous AR rate and Ca2+ ionophore A23187-induced AR rate in 128 patients who accepted IUI treatment, collected their clinical data and analysed the relationship between sperm AR rate and clinical pregnancy rate of IUI. RESULTS: There was no statistical difference between the spontaneous AR rates in the pregnant group and the non-pregnant group (7.7% vs. 7.0%, P>0.05), but there was statistical difference between the induced AR rates(51.9 % vs. 43.5%, P<0.05). There was statistical difference in the clinical pregnancy rate among the 3 IUI groups divided by induced AR rate (≤20.0%, 20.1%-49.9%, and ≥50.0%; 4.8% vs. 12.5% vs. 18.6%, P<0.05). CONCLUSION The spontaneous AR rate has nothing to do with the clinical pregnancy rate of IUI, but the induced AR rate is associated with the clinical pregnancy rate of IUI.
Acrosome Reaction ; drug effects ; physiology ; Adult ; Calcimycin ; pharmacology ; Female ; Humans ; Infertility ; therapy ; Insemination, Artificial, Homologous ; methods ; Male ; Pregnancy ; Pregnancy Rate ; Spermatozoa ; physiology

OBJECTIVE: To determine the sperm-zona pellucida (ZP) binding and ZP-induced acrosome reaction in patients with unexplained infertility, and to discuss the relationship between ZP-induced acrosome reaction and fertilization rate. METHODS: We compared the fertilization rate and good embryo rate in patients with unexplained infertility after fertilization in 2 ways. Based on the causes of infertility, patients were divided into an unexplained infertility group (Group A) and a pure female tubal factor group (Group B). Oocytes which were obtained by super ovulation from 25 patients with unexplained infertility were randomly divided into 2 groups with conventional in vitro fertilization (IVF) (Group A1) and intracytoplasmic sperm injection (ICSI) fertilization (Group A2). The pure female tubal factor group (Group B) had conventional IVF. We conducted sperm-ZP binding and ZP-induced acrosome reaction experiments with 2 groups of men's sperms separately. We compared the number of sperm-egg binding and ZP-induced acrosome reaction rate and discussed the relationship between the ZP-induced acrosome reaction and fertilization rate, and also the fertilization rate, good embryo rate and pregnancy rate in patients with unexplained infertility after fertilization in 2 ways. RESULTS: The average number of sperm-egg binding (78.29 ± 16.31) and the ZP-induced acrosome reaction rate (55.87 ± 27.69) % in Group A were lower than those of Group B [94.63 ± 6.72, (82.53 ± 17.99)%]. The difference between the average number of sperm-egg binding and the ZP-induced acrosome reaction was significant (P <0.01). The fertilization rate of Group A1 was significantly lower than that of Group B and Group A2 (P <0.01). But there was no significant difference in the good embryo rate among the 3 groups. There was no significant difference between Group A2 and B in fertilization rate and good embryo rate (P <0.05). There was no significant difference in pregnancy rate between Group A and B (P <0.05). Fertilization rate and the rate of acrosome reaction had marked positive correlation with statistical significance (r =0.932, P <0.01). CONCLUSION ZP binding and ZP-induced acrosome reaction are very important experiments in sperm function test for patients with unexplained infertility. It can not only effectively avoid no embryo transferring due to complete failure of fertilization but also get a desirable outcome of pregnancy using half-ICSI fertilization in patients with unexplained infertility.
Acrosome Reaction ; Embryo Transfer ; Female ; Fertilization in Vitro ; Humans ; Infertility ; etiology ; therapy ; Male ; Oocytes ; physiology ; Ovulation Induction ; Sperm Injections, Intracytoplasmic ; Sperm-Ovum Interactions ; physiology ; Treatment Outcome ; Zona Pellucida ; physiology

Prior to fertilization sperm has to undergo an activation process known as capaciation, leading to the acrosome reaction. Till now, little is known about the mechanism for preventing premature capacitation in sperm although decapacitation factors from various sources have been thought to be involved. In this study, we report that NYD-SP27, an isoform of phospholipase C Zeta 1 (PLCZ1), is localized to the sperm acrosome in mouse and human spermatozoa by immunofluorescence using a specific antibody. Western blot and double staining analyses show NYD-SP27 becomes detached from sperm, as they undergo capacitation and acrosome reaction. The absence of HCO3-, a key factor in activating capacitation, from the capacitation-inducing medium prevents the loss of NYD-SP27 from sperm. The anti-NYD-SP27 antibody also prevents the loss of NYD-SP27 from sperm, reduced the number of capacitated sperm, inhibited the acrosome reaction induced by ATP and progesterone, and inhibited agonist-induced PLC-coupled Ca2+ mobilization in sperm, which can be mimicked by the PLC inhibitor, U73122. These data strongly suggest that NYD-SP27 is a physiological inhibitor of PLC that acts as an intrinsic decapacitation factor in sperm to prevent premature capacitation and acrosome reaction.
Acrosome ; drug effects ; metabolism ; Acrosome Reaction ; physiology ; Adult ; Animals ; Calcium ; metabolism ; Fluorescent Antibody Technique, Indirect ; Humans ; Immune Sera ; pharmacology ; Male ; Mice ; Middle Aged ; Phosphoinositide Phospholipase C ; immunology ; metabolism ; Sperm Capacitation ; drug effects ; physiology ; Spermatozoa ; drug effects ; metabolism

The aim of this study was to investigate whether a relationship exists between the presence of low numbers of leukocytes in normal ovulatory cervical mucus and sperm quality and lipid content after migration. The percentages of live, motile and morphologically normal spermatozoa, movement parameters assessed by computer-aided sperm analysis (CASA), and ionophore-induced acrosome reaction measured by flow cytometry were determined before and after migration. High-performance liquid chromatography with ultraviolet detection was used to measure the sperm lipid content, including the various diacyl subspecies. The number of leukocytes found in solubilized mucus samples was counted using a haemocytometric method. Overall, the presence of leukocytes in the cervical mucus samples did not significantly influence sperm motility and morphology, sperm kinematic parameters, or the sperm content in sphingomyelin or cholesterol. In contrast, after migration, the decrease in various sperm diacyls and the level of induced acrosome reaction was significantly less pronounced in mucus samples containing>or=10(4) leukocytes than in mucus samples with no or rare leukocytes whereas the level of induced acrosome reaction was higher. The present data suggest that the low level of leukocytes found in normal ovulatory cervical mucus could influence the process of sperm lipid remodelling/capacitation.
Acrosome Reaction ; physiology ; Cervix Mucus ; immunology ; metabolism ; Female ; Humans ; Leukocytes ; cytology ; Lipids ; Male ; Ovulation ; Sperm Motility ; physiology ; Spermatozoa ; cytology ; metabolism ; Tissue Donors

AIMTo determine the cellular distribution of secretory phospholipase A(2) (sPLA(2)) in dependence on the acrosomal state and under the action of elastase released under inflammatory processes from leukocytes.

METHODSAcrosome reaction of spermatozoa was triggered by calcimycin. Human leukocyte elastase was used to simulate inflammatory conditions. To visualize the distribution of sPLA(2) and to determine the acrosomal state, immunofluorescence techniques and lectin binding combined with confocal laser scanning fluorescence microscopy and flow cytometry were used.

RESULTSAlthough sPLA(2) was detected at the acrosome and tail regions in intact spermatozoa, it disappeared from the head region after triggering the acrosome reaction. This release of sPLA(2) was associated with enhanced binding of annexin V-fluoroscein isothiocyanate (FITC) to spermatozoa surfaces, intercalation of ethidium-homodimer I, and binding of FITC-labelled concanavalin A at the acrosomal region. Spermatozoa from healthy subjects treated with elastase were characterized by release of sPLA(2), disturbance of acrosome structure, and loss of vitality.

CONCLUSIONThe ability of spermatozoa to release secretory phospholipase A(2) is related to the acrosomal state. Premature destabilization of the acrosome and loss of sPLA(2) can occur during silent inflammations in the male genital tract. The distribution pattern of sPLA(2) in intact spermatozoa might be an additional parameter for evaluating sperm quality.

Acrosome ; drug effects ; physiology ; Acrosome Reaction ; drug effects ; Annexin A5 ; metabolism ; Anti-Bacterial Agents ; pharmacology ; Calcimycin ; pharmacology ; Ethidium ; Flow Cytometry ; Fluorescent Dyes ; Humans ; In Vitro Techniques ; Male ; Microscopy, Confocal ; Pancreatic Elastase ; metabolism ; Phosphatidylserines ; metabolism ; Phospholipases A2, Secretory ; metabolism ; Semen ; cytology ; drug effects ; Spermatozoa ; drug effects ; enzymology

AIMTo characterize mouse capping protein alpha3 (CPalpha3) during spermatogenesis and sperm maturation.

METHODSWe produced rat anti-CPalpha3 antiserum and examined the expression of CPalpha3 in various mouse tissues using Western blot analysis and the localization of CPalpha3 in testicular and epididymal sperm using immunohistochemical analyses. We also examined how the localization of CPalpha3 and beta-actin (ACTB) in sperm changed after the acrosomal reaction by performing immunohistochemical analyses using anti-CPalpha3 antiserum and anti-actin antibody.

RESULTSWestern blot analysis using specific antiserum revealed that CPalpha3 was expressed specifically in testes. Interestingly, the molecular weight of CPalpha3 changed during sperm maturation in the epididymis. Furthermore, the subcellular localization of CPalpha3 in sperm changed dynamically from the flagellum to the post-acrosomal region of the head during epididymal maturation. The distribution of ACTB was in the post-acrosomal region of the head and the flagellum. After inducing the acrosomal reaction, the CPalpha3 and ACTB localization was virtually identical to the localization before the acrosomal reaction.

CONCLUSIONCPalpha3 might play an important role in sperm morphogenesis and/or sperm function.

Acrosome Reaction ; physiology ; Actins ; metabolism ; Animals ; Blotting, Western ; CapZ Actin Capping Protein ; metabolism ; Cells, Cultured ; Epididymis ; cytology ; metabolism ; Male ; Mice ; Mice, Inbred C57BL ; Sperm Head ; metabolism ; Sperm Tail ; metabolism ; Spermatogenesis ; physiology ; Spermatozoa ; cytology ; metabolism ; Testis ; cytology ; metabolism

AIMTo develop a method for assessing sperm function by measuring released acrosin activity during the acrosome reaction (AR).

METHODSHuman semen samples were obtained from 24 healthy donors with proven fertility after 3-7 days of sexual abstinence. After collection, samples were liquefied for 30 min at room temperature. Standard semen parameters were evaluated according to World Health Organization (WHO) criteria. Calcium ionophore A23187 and progesterone (P4) were used to stimulate the sperm to undergo AR. After treatment, sperm were incubated with the supravital dye Hoechst33258, fixed in a glutaraldehyde-phosphate-buffered saline solution, and the acrosomal status was determined by fluorescence microscopy with fluorescein isothiocyanate-labeled Pisum sativum agglutinin (FITC-PSA). The percentage of sperm undergoing AR (AR%) was compared to sperm acrosin activities as assessed by spectrocolorimetry. The correlation between AR% and acrosin activity was determined by statistical analysis.

RESULTSThe AR% and released acrosin activity were both markedly increased with A23187 and P4 stimulation. Sperm motility and viability were significantly higher after stimulation with P4 versus stimulation with A23187 (P < 0.001). There was a significant positive correlation between released acrosin activity and AR% determined by FITC-PSA staining (r=0.916, P < 0.001).

CONCLUSIONSpectrocolorimetric measurement of released acrosin activity might serve as a reasonable alternative method to evaluate AR.

Acrosin ; physiology ; Acrosome Reaction ; Adult ; China ; Humans ; Male ; Progesterone ; pharmacology ; Semen ; drug effects ; physiology ; Sperm Motility ; drug effects ; physiology