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International Journal of Molecular... Sep 2022Progesterone and prostaglandin E1 are postulated to trigger the human sperm acrosome reaction (AR). However, their reported efficacy is very variable which likely, in...
Progesterone and prostaglandin E1 are postulated to trigger the human sperm acrosome reaction (AR). However, their reported efficacy is very variable which likely, in part, reflects the plethora of experimental conditions and methodologies used to detect this physiologically relevant event. The purpose of this study was to develop an assay for the robust induction and objective measurement of the complete AR. Sperm from healthy volunteers or patients undertaking IVF were treated with a variety of ligands (progesterone, prostaglandin E1 or NHCl, alone or in combinations). AR, motility and intracellular calcium measurements were measured using flow cytometry, computer-assisted sperm analysis (CASA) and fluorimetry, respectively. The AR was significantly increased by the simultaneous application of progesterone, prostaglandin E1 and NHCl, following an elevated and sustained intracellular calcium concentration. However, we observed notable inter- and intra-donor sample heterogeneity of the AR induction. When studying the patient samples, we found no relationship between the IVF fertilization rate and the AR. We conclude that progesterone and prostaglandin E1 alone do not significantly increase the percentage of live acrosome-reacted sperm. This assay has utility for drug discovery and sperm toxicology studies but is not predictive for IVF success.
Topics: Acrosome; Acrosome Reaction; Alprostadil; Calcium; Calcium, Dietary; Humans; Male; Progesterone; Semen; Sperm Motility; Spermatozoa
PubMed: 36232560
DOI: 10.3390/ijms231911253 -
Biology of Reproduction Sep 2014The spermatozoa acrosome reaction (AR) is essential for mammalian fertilization. Few methods allow visualization of AR in real time together with Ca²⁺ imaging. Here,...
The spermatozoa acrosome reaction (AR) is essential for mammalian fertilization. Few methods allow visualization of AR in real time together with Ca²⁺ imaging. Here, we show that FM4-64, a fluorescent dye used to follow exocytosis, reliably reports AR progression induced by ionomycin and progesterone in human spermatozoa. FM4-64 clearly delimits the spermatozoa contour and reports morphological cell changes before, during, and after AR. This strategy unveiled the formation of moving tubular appendages, emerging from acrosome-reacted spermatozoa, which was confirmed by scanning electron microscopy. Alternate wavelength illumination allowed concomitant imaging of FM4-64 and Fluo-4, a Ca²⁺ indicator. These AR and intracellular Ca²⁺ ([Ca²⁺]i) recordings revealed that the presence of [Ca²⁺]i oscillations, both spontaneous and progesterone induced, prevents AR in human spermatozoa. Notably, the progesterone-induced AR is preceded by a second [Ca²⁺]i peak and ~40% of reacting spermatozoa also manifest a slow [Ca²⁺]i rise ~2 min before AR. Our findings uncover new AR features related to [Ca²⁺]i.
Topics: Acrosome Reaction; Aniline Compounds; Calcium Ionophores; Calcium Signaling; Cell Shape; Cell Surface Extensions; Cell Survival; Female; Fluorescent Dyes; Humans; Ionomycin; Kinetics; Male; Microscopy, Electron, Scanning; Progesterone; Pyridinium Compounds; Quaternary Ammonium Compounds; Semen Analysis; Single-Cell Analysis; Spermatozoa; Xanthenes
PubMed: 25100708
DOI: 10.1095/biolreprod.114.119768 -
International Journal of Molecular... Nov 2023To acquire the capacity to fertilize the oocyte, mammalian spermatozoa must undergo a series of biochemical reactions in the female reproductive tract, which are... (Review)
Review
To acquire the capacity to fertilize the oocyte, mammalian spermatozoa must undergo a series of biochemical reactions in the female reproductive tract, which are collectively called capacitation. The capacitated spermatozoa subsequently interact with the oocyte zona-pellucida and undergo the acrosome reaction, which enables the penetration of the oocyte and subsequent fertilization. However, the spontaneous acrosome reaction (sAR) can occur prematurely in the sperm before reaching the oocyte cumulus oophorus, thereby jeopardizing fertilization. One of the main processes in capacitation involves actin polymerization, and the resulting F-actin is subsequently dispersed prior to the acrosome reaction. Several biochemical reactions that occur during sperm capacitation, including actin polymerization, protect sperm from sAR. In the present review, we describe the protective mechanisms that regulate sperm capacitation and prevent sAR.
Topics: Animals; Male; Female; Acrosome Reaction; Actins; Semen; Spermatozoa; Actin Cytoskeleton; Mammals; Acrosome
PubMed: 38069328
DOI: 10.3390/ijms242317005 -
Andrology Mar 2014Zona pellucida-based induction of acrosome reaction (AR) is a popular and well-accepted hypothesis. However, this hypothesis is being challenged in recent years and it...
Zona pellucida-based induction of acrosome reaction (AR) is a popular and well-accepted hypothesis. However, this hypothesis is being challenged in recent years and it has been proposed that the cumulus cells might be the site of AR. In our previous study, we reported the presence of a synaptic protein Liprin α3 on sperm acrosome, and proposed its role in AR. This study was designed to understand the role of Liprin α3 and its interacting proteins in regulation of AR. It is observed that the presence of anti-Liprin α3 antibody inhibits the process of AR. Colocalization experiments demonstrate the coexistence of leucocyte antigen related (LAR) protein, Rab-interacting molecule (RIM) and Liprin α3 on sperm acrosome thereby completing the identification of all the members of RIM/MUNC/Rab3A/liprinα complex required for membrane fusion. This study demonstrates the effect of LAR ligands such as Syndecans, Nidogens and LAR wedge domain peptide on AR. We could see an increase in AR in presence of these ligands. On the basis of these data, we speculate that in presence of ligands or wedge peptide, LAR undergoes dimerization leading to inhibition of phosphatase activity and increase in AR. The presence of one of the ligands Syndecan-1 on cumulus cells led us to hypothesize that it is Syndecan which induces AR in vivo and thus another site of AR could lie in cumulus.
Topics: Acrosome; Acrosome Reaction; Animals; Antibodies; Cumulus Cells; Dimerization; Humans; Ligands; Male; Membrane Glycoproteins; Mice; Rats; Receptor-Like Protein Tyrosine Phosphatases, Class 2; Spermatozoa; Syndecans; Vesicular Transport Proteins
PubMed: 24327330
DOI: 10.1111/j.2047-2927.2013.00167 -
Asian Journal of Andrology Jan 2011To bind and fertilize the egg, the spermatozoon should undergo few biochemical and motility changes in the female reproductive tract collectively called capacitation.... (Review)
Review
To bind and fertilize the egg, the spermatozoon should undergo few biochemical and motility changes in the female reproductive tract collectively called capacitation. The capacitated spermatozoon binds to the egg zona pellucida, and then undergoes the acrosome reaction (AR), which allows its penetration into the egg. The mechanisms regulating sperm capacitation and the AR are not completely understood. In the present review, we summarize some data regarding the role and regulation of the epidermal growth factor receptor (EGFR) in these processes. In the capacitation process, the EGFR is partially activated by protein kinase A (PKA), resulting in phospholipase D (PLD) activation and actin polymerization. Protein kinase C alpha (PKCα), which is already activated at the beginning of the capacitation, also participates in PLD activation. Further activation of the EGFR at the end of the capacitation enhances intracellular Ca(2+) concentration leading to F-actin breakdown and allows the AR to take place. Under in vivo conditions, the EGFR can be directly activated by its known ligand epidermal growth factor (EGF), and indirectly by activating PKA or by transactivation mediated by G protein-coupled receptors (GPCRs) activation or by ouabain. Under physiological conditions, sperm PKA is activated mainly by bicarbonate, which activates the soluble adenylyl cyclase to produce cyclic adenosine monophosphate (cAMP), the activator of PKA. The GPCR activators angiotensin II or lysophosphatidic acid, as well as ouabain and EGF are physiological components present in the female reproductive tract.
Topics: Acrosome Reaction; Actins; Animals; Cyclic AMP-Dependent Protein Kinases; ErbB Receptors; Male; Phosphatidylinositol 3-Kinases; Protein Kinase C; Signal Transduction; Sperm Capacitation; Spermatozoa
PubMed: 21200378
DOI: 10.1038/aja.2010.78 -
Journal of Andrology 2002Identification of norepinephrine (NE) within the microenvironment of the bovine oviduct suggests a potential role for catecholamines in the events surrounding...
Identification of norepinephrine (NE) within the microenvironment of the bovine oviduct suggests a potential role for catecholamines in the events surrounding fertilization. Previous studies have shown that the catecholamines capacitate and induce the acrosome reaction in spermatozoa from several species. The current project was undertaken to investigate the role of catecholamines in bovine sperm capacitation and the acrosome reaction. Freshly ejaculated bovine spermatozoa were incubated in NE (0-1000 ng/mL) and induced to acrosome-react with lysophosphatidylcholine (LPC). Additionally, spermatozoa capacitated with heparin were incubated with NE (0-1000 ng/mL) to assess its ability to induce the acrosome-reaction in capacitated spermatozoa. Concentrations of NE were chosen on the basis of physiological concentrations previously determined for bovine oviductal fluid. NE at concentrations of 10 and 20 ng/mL capacitated bovine spermatozoa after 2 hours of incubation. Additionally, spermatozoa incubated for 2 hours with heparin were induced to acrosome-react with 10 and 20 ng/mL NE. Interestingly, higher concentrations of NE inhibited both capacitation and the acrosome reaction. Incubating spermatozoa with dopamine or epinephrine did not result in capacitation or the acrosome reaction, suggesting that the action of NE was specific to that catecholamine. The ability of NE to capacitate or induce the acrosome reaction appears to be dependent on the presence of another membrane-destabilizing factor. Although adrenergic receptors have not been identified on spermatozoa from any species, the action of NE on spermatozoa may be a receptor-mediated event. This study suggests a possible function for oviductal catecholamines in sperm preparation prior to fertilization.
Topics: Acrosome Reaction; Animals; Cattle; Dopamine; Epinephrine; In Vitro Techniques; Male; Norepinephrine; Sperm Capacitation; Spermatozoa; Sympathomimetics
PubMed: 12002437
DOI: No ID Found -
Experimental Animals 2014Despite numerous studies on mammalian fertilization, the mechanisms of fertilization-including the timing of acrosome reaction-remain largely unknown; more accurately... (Review)
Review
Despite numerous studies on mammalian fertilization, the mechanisms of fertilization-including the timing of acrosome reaction-remain largely unknown; more accurately described, the classical theory built upon years of layered experimental data is being challenged by recent conflicting evidence provided by gene-manipulated animals. Although in vitro fertilization remains our central research tool, the classical theory's decline reminds us of the importance of in vivo observations. Here, I describe the essential roles of gene-manipulated animals in elucidating the mechanism of fertilization and the pitfalls of in vitro fertilization studies trapping many researchers.
Topics: Acrosome Reaction; Animals; Animals, Genetically Modified; Female; Fertilization; Fertilization in Vitro; Male; Sperm-Ovum Interactions
PubMed: 24974794
DOI: 10.1538/expanim.63.357 -
Investigative and Clinical Urology May 2021Phosphodiesterase type 5 (PDE5) inhibitors are effective treatments for erectile dysfunction, and several recent studies have reported positive effects of PDE5...
PURPOSE
Phosphodiesterase type 5 (PDE5) inhibitors are effective treatments for erectile dysfunction, and several recent studies have reported positive effects of PDE5 inhibitors on semen parameters as well. However, the data are still controversial. We investigated the effect of PDE5 inhibitors on sperm function by analyzing sperm motility and acrosome reaction.
MATERIALS AND METHODS
This study included young healthy men who underwent fertility evaluation; 32 cases were finally included. Men were excluded if they used a PDE5 inhibitor within 2 weeks or if they had insufficient semen volume (≤2 mL), leukocytospermia, or a genitourinary infection. Changes in sperm motility and acrosome reaction were determined after exposure to the maximal semen concentration of oral intake of sildenafil (100 mg) or tadalafil (20 mg).
RESULTS
Mean age of the participants was 35.4±4.9 years, mean sperm concentration was 68.7±32.4 ×10⁶/mL, and mean sperm motility was 50.38%±8.41%. All three groups (control, sildenafil, tadalafil) experienced trends of decreased average sperm motility over time, but these changes were not significant. There were no significant differences between the three groups in the acrosome reaction after 120 minutes of drug exposure, either. The maximal semen concentration of oral intake of sildenafil (100 mg) or tadalafil (20 mg) did not substantially affect sperm motility or acrosome reaction.
CONCLUSIONS
Our results suggest that on-demand use of a PDE5 inhibitor is safe and useful for the male partner of an infertile couple; however, further studies are warranted for daily PDE5 inhibitor use.
Topics: Acrosome Reaction; Adult; Cell Culture Techniques; Humans; Male; Phosphodiesterase 5 Inhibitors; Semen Analysis; Sildenafil Citrate; Sperm Count; Sperm Motility; Tadalafil
PubMed: 33943054
DOI: 10.4111/icu.20200394 -
Physiological Reviews Apr 1999Fertilization is a matter of life or death. In animals of sexual reproduction, the appropriate communication between mature and competent male and female gametes... (Review)
Review
Fertilization is a matter of life or death. In animals of sexual reproduction, the appropriate communication between mature and competent male and female gametes determines the generation of a new individual. Ion channels are key elements in the dialogue between sperm, its environment, and the egg. Components from the outer layer of the egg induce ion permeability changes in sperm that regulate sperm motility, chemotaxis, and the acrosome reaction. Sperm are tiny differentiated terminal cells unable to synthesize protein and difficult to study electrophysiologically. Thus understanding how sperm ion channels participate in fertilization requires combining planar bilayer techniques, in vivo measurements of membrane potential, intracellular Ca2+ and intracellular pH using fluorescent probes, patch-clamp recordings, and molecular cloning and heterologous expression. Spermatogenic cells are larger than sperm and synthesize the ion channels that will end up in mature sperm. Correlating the presence and cellular distribution of various ion channels with their functional status at different stages of spermatogenesis is contributing to understand their participation in differentiation and in sperm physiology. The multi-faceted approach being used to unravel sperm ion channel function and regulation is yielding valuable information about the finely orchestrated events that lead to sperm activation, induction of the acrosome reaction, and in the end to the miracle of life.
Topics: Acrosome Reaction; Animals; Female; Humans; Ion Channels; Male; Spermatozoa
PubMed: 10221988
DOI: 10.1152/physrev.1999.79.2.481 -
The Journal of Reproduction and... Aug 2010Motility and fertilizing ability are known to be two important physiological attributes of a mature sperm, yet the mechanism by which spermatozoa mature and become...
Motility and fertilizing ability are known to be two important physiological attributes of a mature sperm, yet the mechanism by which spermatozoa mature and become motile remains largely unknown. It has been shown that nerve growth factor (NGF) is a protein essential for the development, maintenance and survival of the peripheral and central nervous systems. However, the presence of high levels of NGF protein and mRNA do not correlate with the innervations by NGF sensitive fibers in tissues such as the testis, prostate and seminal vesicles. These observations have shifted the attention of research to the role of NGF outside of the nervous system. Here, we demonstrate that NGF and its receptors TrkA and p75 are widely expressed in the testis, accessory reproductive organ, and the epididymal sperms. We also show that NGF stimulates two important aspects of sperm functions, motility and the acrosome reaction, in a time- and dose-dependent manner. NGF activated the sperm cell acrosome reaction, while addition of inhibitors specific for MAPK kinase significantly blocked the sperm acrosome reaction. Taken together, our findings suggest that NGF plays an integral role in sperm motility and the acrosome reaction through, at least in part, the MAPK signalling pathway.
Topics: Acrosome Reaction; Animals; Cricetinae; Dose-Response Relationship, Drug; Male; Mesocricetus; Mitogen-Activated Protein Kinase Kinases; Nerve Growth Factor; Receptor, Nerve Growth Factor; Receptor, trkA; Signal Transduction; Sperm Motility; Spermatozoa; Tissue Distribution
PubMed: 20519834
DOI: 10.1262/jrd.09-219n