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In Vivo (Athens, Greece) 2022The process of fertilization includes sperm capacitation, hyperactivation, an acrosome reaction and the release of acrosome enzymes, membrane fusion and channel... (Review)
Review
The process of fertilization includes sperm capacitation, hyperactivation, an acrosome reaction and the release of acrosome enzymes, membrane fusion and channel formation, the release of the sperm nucleus, and gamete fusion. This process is closely related to the shape and vitality of the sperm, acrosome enzyme release, and the zona pellucida structure of the egg, as well as the opening and closing of various ion (e.g., calcium) channels, the regulation of signaling pathways such as cyclic adenosine monophosphate-protein kinase A, the release of progesterone, and the coupling of G-proteins. The interaction among multiple factors and their precise regulation give rise to multiple cascading regulatory processes. Problems with any factor will affect the success rate of fertilization. Recent studies have shown that with rapid societal development, the incidence of male infertility is increasing and occurs at younger ages. According to World Health Organization statistics, 15% of couples of childbearing ages have infertility problems, of which 50% are caused by male factors. Additionally, the cause of infertility cannot be identified in as many as 60% to 75% of male infertility patients. In this article, we review the research progress on the microregulation of fertilization and mechanisms underlying this process to identify causes and develop novel prevention and treatment strategies for male infertility.
Topics: Acrosome Reaction; Humans; Infertility, Male; Male; Semen; Sperm Capacitation; Spermatozoa
PubMed: 36099087
DOI: 10.21873/invivo.12926 -
Biological Reviews of the Cambridge... Apr 2020Mammalian sperm must spend a minimum period of time within a female reproductive tract to achieve the capacity to fertilize oocytes. This phenomenon, termed sperm... (Review)
Review
Mammalian sperm must spend a minimum period of time within a female reproductive tract to achieve the capacity to fertilize oocytes. This phenomenon, termed sperm 'capacitation', was discovered nearly seven decades ago and opened a window into the complexities of sperm-female interaction. Capacitation is most commonly used to refer to a specific combination of processes that are believed to be widespread in mammals and includes modifications to the sperm plasma membrane, elevation of intracellular cyclic AMP levels, induction of protein tyrosine phosphorylation, increased intracellular Ca levels, hyperactivation of motility, and, eventually, the acrosome reaction. Capacitation is only one example of post-ejaculatory modifications to sperm (PEMS) that are widespread throughout the animal kingdom. Although PEMS are less well studied in non-mammalian taxa, they likely represent the rule rather than the exception in species with internal fertilization. These PEMS are diverse in form and collectively represent the outcome of selection fashioning complex maturational trajectories of sperm that include multiple, sequential phenotypes that are specialized for stage-specific functionality within the female. In many cases, PEMS are critical for sperm to migrate successfully through the female reproductive tract, survive a protracted period of storage, reach the site of fertilization and/or achieve the capacity to fertilize eggs. We predict that PEMS will exhibit widespread phenotypic plasticity mediated by sperm-female interactions. The successful execution of PEMS thus has important implications for variation in fitness and the operation of post-copulatory sexual selection. Furthermore, it may provide a widespread mechanism of reproductive isolation and the maintenance of species boundaries. Despite their possible ubiquity and importance, the investigation of PEMS has been largely descriptive, lacking any phylogenetic consideration with regard to divergence, and there have been no theoretical or empirical investigations of their evolutionary significance. Here, we (i) clarify PEMS-related nomenclature; (ii) address the evolutionary origin, maintenance and divergence in PEMS in the context of the protracted life history of sperm and the complex, selective environment of the female reproductive tract; (iii) describe taxonomically widespread types of PEMS: sperm activation, chemotaxis and the dissociation of sperm conjugates; (iv) review the occurence of PEMS throughout the animal kingdom; (v) consider alternative hypotheses for the adaptive value of PEMS; (vi) speculate on the evolutionary implications of PEMS for genomic architecture, sexual selection, and reproductive isolation; and (vii) suggest fruitful directions for future functional and evolutionary analyses of PEMS.
Topics: Acrosome Reaction; Animals; Ejaculation; Male; Sperm Capacitation; Spermatozoa
PubMed: 31737992
DOI: 10.1111/brv.12569 -
Cold Spring Harbor Perspectives in... Oct 2015Vertebrate reproduction requires a myriad of precisely orchestrated events-in particular, the maternal production of oocytes, the paternal production of sperm,... (Review)
Review
Vertebrate reproduction requires a myriad of precisely orchestrated events-in particular, the maternal production of oocytes, the paternal production of sperm, successful fertilization, and initiation of early embryonic cell divisions. These processes are governed by a host of signaling pathways. Protein kinase and phosphatase signaling pathways involving Mos, CDK1, RSK, and PP2A regulate meiosis during maturation of the oocyte. Steroid signals-specifically testosterone-regulate spermatogenesis, as does signaling by G-protein-coupled hormone receptors. Finally, calcium signaling is essential for both sperm motility and fertilization. Altogether, this signaling symphony ensures the production of viable offspring, offering a chance of genetic immortality.
Topics: Acrosome Reaction; Animals; Calcium Signaling; Cell Division; Cell Proliferation; Female; Fertilization; Humans; Male; Meiosis; Oocytes; Reproduction; Signal Transduction; Sperm Capacitation; Spermatogenesis; Spermatozoa; Stem Cells; Vertebrates; Zygote
PubMed: 26430215
DOI: 10.1101/cshperspect.a006064 -
Andrology Jan 2023Stress and elevated cortisol levels have negative effects on fertility, although there is controversy about the effect of cortisol on human sperm. One study reported...
BACKGROUND
Stress and elevated cortisol levels have negative effects on fertility, although there is controversy about the effect of cortisol on human sperm. One study reported that hydrocortisone (HC), the synthetic form of cortisol, does not activate CatSper channel but is able to inhibit its activation by progesterone (Pg). However, subsequent reports showed that HC has an agonist effect on CatSper, producing intracellular Ca ([Ca ] ) increases. These studies were performed using only electrophysiological techniques and fluorometric measurements of Ca . Therefore, it is important to evaluate the effects of different HC concentrations on human sperm physiology using other approaches and techniques.
OBJECTIVE
To analyze the effects of different HC concentrations on human sperm physiology and to evaluate the association of perceived stress, anxiety and depression with acrosome reaction (AR), and semen quality.
MATERIALS AND METHODS
In capacitated human sperm, we tested the effects of HC on [Ca ] mobilization and AR. Furthermore, the perceived stress and symptoms of anxiety and depression were evaluated with standardized psychometric tests.
RESULTS
HC induces a low increase in [Ca ] compared to Pg response while, at higher concentrations, HC inhibits the Pg-induced Ca response. Also, low concentrations of HC induce AR and when co-incubating it with Pg, the percentages of AR are decreased. Finally, the anxiety symptoms are negatively correlated with Pg induced AR and semen quality.
DISCUSSION
HC has an agonist effect on [Ca ] mobilization and AR. However, our data also suggest that HC may compete for the binding site of Pg. Additionally, the association between anxiety and decreased AR could be explained by high cortisol levels.
CONCLUSION
Our data showed that HC interferes with the Pg action. Therefore, the negative correlation between anxiety symptoms and Pg-induced AR is due to the accompanying high cortisol levels of this condition and its competitive action with Pg.
Topics: Humans; Male; Acrosome Reaction; Hydrocortisone; Semen Analysis; Semen; Spermatozoa; Progesterone; Calcium; Acrosome
PubMed: 36251513
DOI: 10.1111/andr.13319 -
Biological Research 2011Spermatozoon acrosome reaction is an exocytotic event of the utmost importance for the development of mammalian fertilisation. Current evidence shows that the triggering... (Review)
Review
Spermatozoon acrosome reaction is an exocytotic event of the utmost importance for the development of mammalian fertilisation. Current evidence shows that the triggering of the acrosome reaction (AR) could be regulated by the action of diverse compounds, namely, metabolites, neurotransmitters and hormones. The aim of the present review is to describe the modulating effects of several compounds that have been classified as inductors or inhibitors of acrosome reaction. Among AR inductors, it is necessary to mention progesterone, angiotensin II, atrial natriuretic peptide, cathecolamines, insulin, leptin, relaxin and other hormones. Regarding the inhibitors, oestradiol and epidermal growth factor are among the substances that retard AR. It is worth mentioning that gamma-aminobutyric acid, a neurotransmitter known to be an inhibitor in the central nervous system, has been shown to induce AR. The multiple hormones located in the fluids of the female reproductive tract are also likely to act as subtle regulators of AR, constituting a fundamental aspect for the development of successful fertilisation. Finally, it is necessary to emphasise that the study of regulation exerted by hormones and other compounds on AR is essential for further understanding of mammalian reproductive biology, especially spermatozoon physiology.
Topics: Acrosome Reaction; Animals; Female; Hormones; Humans; Male; Mammals; Sperm Capacitation; Spermatozoa
PubMed: 22513418
DOI: No ID Found -
Andrology Mar 2018To study apoptosis as a functional pathway in mature spermatozoa and apoptosis correlated to the acrosome reaction via the intracellular calcium concentration, semen...
To study apoptosis as a functional pathway in mature spermatozoa and apoptosis correlated to the acrosome reaction via the intracellular calcium concentration, semen samples from 27 healthy human donors were treated with inducers of apoptosis (betulinic acid, thapsigargin), inducers of the acrosome reaction (thapsigargin, calcium ionophore) or hydrogen peroxide to produce reactive oxygen species with and without prior incubation with a calcium chelator. Computer-assisted sperm analysis, flow cytometry, and transmission electron microscopy were performed to analyze changes in the acrosomal status and in apoptotic features. Betulinic acid, thapsigargin, and the calcium ionophore treatment resulted in an increased number of sperm cells with caspase 9 and caspase 3 activation, disrupted mitochondrial membrane potential, and a reacted acrosome. Sperm motility was decreased in all cases. Transmission electron analyses showed ultra-morphological changes, such as membrane integrity, membrane blebbing, the formation of head vacuoles, defects of the nuclear envelope, nuclear fragmentation, and the acrosome reaction. Acrosome reaction and apoptotic features decreased due to the reduction in intracellular calcium by the calcium chelator NP-EGTA, AM. Therefore, apoptotic cell death in acrosome-reacted sperm cells mediated by high intracellular calcium levels is possible.
Topics: Acrosome Reaction; Apoptosis; Calcium; Flow Cytometry; Humans; Male; Membrane Potential, Mitochondrial; Oxidative Stress; Pentacyclic Triterpenes; Sperm Motility; Spermatozoa; Thapsigargin; Triterpenes; Betulinic Acid
PubMed: 29438593
DOI: 10.1111/andr.12467 -
The International Journal of... 2008The acrosome reaction is a secretory event that must be completed by the sperm of many animal species prior to fusion with eggs. In mammals, exocytosis in triggered by... (Review)
Review
The acrosome reaction is a secretory event that must be completed by the sperm of many animal species prior to fusion with eggs. In mammals, exocytosis in triggered by ZP3, a glycoprotein component of the egg pellucida, following gamete contact. ZP3 promotes a sustained influx of Ca2+ into sperm that is necessary for the acrosome reaction. Here, we discuss the mechanism by which ZP3 generates Ca2+ entry, as well as the upstream events leading to this influx and downstream processes that couple it with exocytosis.
Topics: Acrosome Reaction; Animals; Calcium; Calcium Channels; Egg Proteins; Exocytosis; Female; Glycoproteins; Humans; Male; Membrane Glycoproteins; Mice; Models, Biological; Receptors, Cell Surface; Signal Transduction; Spermatozoa; Zona Pellucida; Zona Pellucida Glycoproteins
PubMed: 18649263
DOI: 10.1387/ijdb.082696hf -
Frontiers in Bioscience (Landmark... Mar 2019Mammalian fertilization that culminates by fusion of the male and female gametes is intricately regulated within the female reproductive tract. To become competent to... (Review)
Review
Mammalian fertilization that culminates by fusion of the male and female gametes is intricately regulated within the female reproductive tract. To become competent to fertilize an egg, the mammalian spermatozoa that enter the female reproductive tract must undergo a series of physiological changes, including hyperactivation, and capacitation. For reaching full competency, the acrosome, a specialized membrane-bound organelle that covers the anterior part of the sperm head, must undergo an acrosome reaction. For becoming competent to bind an ovum, and to penetrate the zona pellucida and cumulus, many sperm proteins are released in the course of the acrosome reaction. Ultimately, the acrosome binds to the oolemma and fusion of sperm and egg occurs. In this review, we outline current understanding of the roles and effects of some essential sperm proteins and their functions during fertilization in the female reproductive tract.
Topics: Acrosome Reaction; Animals; Antigens; Cell Adhesion Molecules; Female; Fertilins; Fertilization; Genitalia, Female; Humans; Hyaluronoglucosaminidase; Immunoglobulins; Male; Membrane Proteins; Mice; Receptors, Cell Surface; Spermatozoa; Zona Pellucida
PubMed: 30844709
DOI: 10.2741/4747 -
Biochemical and Biophysical Research... Aug 2014Intracellular pH (pHi) regulation is essential for cell function. Notably, several unique sperm ion transporters and enzymes whose elimination causes infertility are... (Review)
Review
Intracellular pH (pHi) regulation is essential for cell function. Notably, several unique sperm ion transporters and enzymes whose elimination causes infertility are either pHi dependent or somehow related to pHi regulation. Amongst them are: CatSper, a Ca(2+) channel; Slo3, a K(+) channel; the sperm-specific Na(+)/H(+) exchanger and the soluble adenylyl cyclase. It is thus clear that pHi regulation is of the utmost importance for sperm physiology. This review briefly summarizes the key components involved in pHi regulation, their characteristics and participation in fundamental sperm functions such as motility, maturation and the acrosome reaction.
Topics: Acrosome Reaction; Adenylyl Cyclases; Animals; Carbonic Anhydrases; Chemotaxis; Humans; Hydrogen-Ion Concentration; Intracellular Fluid; Ion Channels; Ion Pumps; Male; Models, Biological; Sea Urchins; Signal Transduction; Sperm Capacitation; Sperm Motility; Spermatozoa
PubMed: 24887564
DOI: 10.1016/j.bbrc.2014.05.100 -
Andrology Jan 2019Sperm capacitation is essential for proper fertilization and is associated with increased sperm hyperactivity (HA) and acrosome reaction (AR). For successful...
BACKGROUND
Sperm capacitation is essential for proper fertilization and is associated with increased sperm hyperactivity (HA) and acrosome reaction (AR). For successful fertilization, AR timing is critical; accordingly, early spontaneous AR may not facilitate fertilization. Paraoxonase 1 (PON1) possesses antioxidant properties which affect sperm capacitation. The association between PON1, semen parameters, and capacitation is not fully understood.
OBJECTIVE
To study PON1 activity in relation to human sperm hyperactivity and AR.
MATERIALS AND METHODS
Semen samples were collected, and parameters were determined (volume, concentration, total sperm count, percentage total motility, and percentage normal morphology) according to World Health Organization (WHO) guidelines. AR and hyperactivity were evaluated using FITC-PSA, staining, and computer-aided sperm analysis (CASA). PON1 activity was assessed using arylesterase activity assay.
RESULTS
Purified PON1 inhibited both sperm hyperactivity and AR in a dose-dependent manner. Native semen PON1 activity was positively associated with higher sperm concentration and negatively associated with spontaneous acrosome reaction (sAR).
DISCUSSION AND CONCLUSION
PON1 may have a positive effect on fertility via its ability to prevent early spontaneous sperm capacitation and AR before reaching the female genital tract.
Topics: Acrosome Reaction; Antioxidants; Aryldialkylphosphatase; Humans; Male; Semen Analysis; Sperm Capacitation; Sperm Count; Sperm Motility; Spermatozoa
PubMed: 30225889
DOI: 10.1111/andr.12552