Lowered levels of bicarbonate in seminal plasma cause the poor sperm motility in human infertile patients

pH Homeodynamics and Male Fertility: A Coordinated Regulation of Acid-Based Balance during Sperm Journey to Fertilization

pH homeostasis is crucial for spermatogenesis, sperm maturation, sperm physiological function, and fertilization in mammals. HCO3- and H+ are the most significant factors involved in regulating pH homeostasis in the male reproductive system. Multiple pH-regulating transporters and ion channels localize in the testis, epididymis, and spermatozoa, such as HCO3- transporters (solute carrier family 4 and solute carrier family 26 transporters), carbonic anhydrases, and H+-transport channels and enzymes (e.g., Na+-H+ exchangers, monocarboxylate transporters, H+-ATPases, and voltage-gated proton channels). Hormone-mediated signals impose an influence on the production of some HCO3- or H+ transporters, such as NBCe1, SLC4A2, MCT4, etc. Additionally, ion channels including sperm-specific cationic channels for Ca2+ (CatSper) and K+ (SLO3) are directly or indirectly regulated by pH, exerting specific actions on spermatozoa. The slightly alkaline testicular pH is conducive to spermatogenesis, whereas the epididymis's low HCO3- concentration and acidic lumen are favorable for sperm maturation and storage. Spermatozoa pH increases substantially after being fused with seminal fluid to enhance motility. In the female reproductive tract, sperm are subjected to increasing concentrations of HCO3- in the uterine and fallopian tube, causing a rise in the intracellular pH (pHi) of spermatozoa, leading to hyperpolarization of sperm plasma membranes, capacitation, hyperactivation, acrosome reaction, and ultimately fertilization. The physiological regulation initiated by SLC26A3, SLC26A8, NHA1, sNHE, and CFTR localized in sperm is proven for certain to be involved in male fertility. This review intends to present the key factors and characteristics of pHi regulation in the testes, efferent duct, epididymis, seminal fluid, and female reproductive tract, as well as the associated mechanisms during the sperm journey to fertilization, proposing insights into outstanding subjects and future research trends.

Semen rheology and its relation to male infertility

Infertility affects 15% of couples of reproductive age worldwide. In spite of many advances in understanding and treating male infertility, there is still a number of issues that need further investigation and translation to the clinic. Here, we review the current knowledge and practice concerning semen rheology and its relation with pathological states affecting male infertility. Although it is well recognized that altered rheological properties of semen can impair normal sperm movement in the female reproductive tract, routine semen analysis is mostly focused on number, motility and morphology of spermatozoa, and includes only an approximate, operator-dependent measure of semen viscosity. The latter is based on the possible formation of a liquid thread from a pipette where a semen sample has been aspirated, a method that is sensitive not only to viscosity but also to elongational properties and surface tension of semen. The formation of a liquid thread is usually associated with a gel-like consistency of the sample and changes in spermatozoa motility in such a complex medium are still to be fully elucidated. The aim of this review is to point out that a more quantitative and reliable characterization of semen rheology is in order to improve the current methods of semen analysis and to develop additional tools for the diagnosis and treatment of male infertility.

The therapeutic importance of acid-base balance

Baking soda and vinegar have been used as home remedies for generations and today we are only a mouse-click away from claims that baking soda, lemon juice, and apple cider vinegar are miracles cures for everything from cancer to COVID-19. Despite these specious claims, the therapeutic value of controlling acid-base balance is indisputable and is the basis of Food and Drug Administration-approved treatments for constipation, epilepsy, metabolic acidosis, and peptic ulcers. In this narrative review, we present evidence in support of the current and potential therapeutic value of countering local and systemic acid-base imbalances, several of which do in fact involve the administration of baking soda (sodium bicarbonate). Furthermore, we discuss the side effects of pharmaceuticals on acid-base balance as well as the influence of acid-base status on the pharmacokinetic properties of drugs. Our review considers all major organ systems as well as information relevant to several clinical specialties such as anesthesiology, infectious disease, oncology, dentistry, and surgery.

Increase of leucocyte-derived extracellular traps (ETs) in semen samples from human acute epididymitis patients-a pilot study

PURPOSE

To study the effector mechanism against pathogens of polymorphonuclear neutrophils (PMN) and macrophages, called ETosis, involving the release of extracellular traps (ETs) in patients with acute epididymitis. To assess the different ET phenotypes present in semen samples and to identify correlations between ETosis and clinical parameters.

MATERIALS AND METHODS

Samples from patients diagnosed with acute epididymitis were examined and compared with samples from uninfected controls. Biochemical analyses of seminal fluid included determination of peroxidase, α-glucosidase, fructose, and elastase levels. ETosis in semen was determined through presence of citrullinated histones, global histones, and extracellular DNA. Different ETosis phenotypes such as spread ETs, aggregated ETs, and diffuse ETs were identified by co-localisation of extruded DNA with myeloperoxidase and global histones. Anti-CD15⁺ and anti-CD68⁺ antibodies were used to identify different cell lines.

RESULTS

Revealed a high number of ETs compared with the control group. The mean number of CD15⁺PMN and CD68⁺ macrophages was higher in the acute epididymitis group. ETosis increase in ejaculates correlated with clinical parameters such as enhancement of elastase concentrations and diminution of fructose in the semen.

CONCLUSIONS

This work shows for the first time the presence of ETs and their components in semen from patients with acute epididymitis. The presence of infections is an important factor for induction of ETs in semen. Furthermore, the presence of ETosis in ejaculates is suggestive of developing infectious processes and might possibly have a diagnostic value.

Human Sperm Capacitation Involves the Regulation of the Tyr-Phosphorylation Level of the Anion Exchanger 1 (AE1)

Bicarbonate uptake is one of the early steps of capacitation, but the identification of proteins regulating anion fluxes remains elusive. The aim of this study is to investigate the role of sperm solute carrier 4 (SLC4) A1 (spAE1) in the capacitation process. The expression, location, and tyrosine-phosphorylation (Tyr-P) level of spAE1 were assessed. Thereby, it was found that 4,4′-Diisothiocyano-2,2′-stilbenedisulfonic acid (DIDS), an SLC4 family channel blocker, inhibited capacitation in a dose-dependent manner by decreasing acrosome reaction (ARC% 24.5 ± 3.3 vs. 64.9 ± 4.3, p < 0.05) and increasing the percentage of not viable cells (NVC%), comparable to the inhibition by I-172, a cystic fibrosis transmembrane conductance regulator (CFTR) blocker (AR% 30.5 ± 4.4 and NVC% 18.6 ± 2.2). When used in combination, a synergistic inhibitory effect was observed with a remarkable increase of the percentage of NVC (45.3 ± 4.1, p < 0.001). spAE1 was identified in sperm membrane as a substrate for Tyr-protein kinases Lyn and Syk, which were identified as both soluble and membrane-bound pools. spAE1-Tyr-P level increased in the apical region of sperm under capacitating conditions and was negatively affected by I-172 or DIDS, and, to a far greater extent, by a combination of both. In conclusion, we demonstrated that spAE1 is expressed in sperm membranes and it is phosphorylated by Syk, but above all by Lyn on Tyr359, which are involved in sperm viability and capacitation.

Capacitation-associated alkalization in human sperm is differentially controlled at the subcellular level

Capacitation in mammalian sperm involves the accurate balance of intracellular pH (pHi), but the mechanisms controlling this process are not fully understood, particularly regarding the spatiotemporal regulation of the proteins involved in pHi modulation. Here, we employed an image-based flow cytometry technique combined with pharmacological approaches to study pHi dynamics at the subcellular level during capacitation. We found that, upon capacitation induction, sperm cells undergo intracellular alkalization in the head and principal piece regions. The observed localized pHi increases require the initial uptake of HCO3-, which is mediated by several proteins acting consistently with their subcellular localization. Hv1 proton channel (also known as HVCN1) and cAMP-activated protein kinase (protein kinase A, PKA) antagonists impair alkalization mainly in the principal piece. Na+/HCO3- cotransporter (NBC) and cystic fibrosis transmembrane regulator (CFTR) antagonists impair alkalization only mildly, predominantly in the head. Motility measurements indicate that inhibition of alkalization in the principal piece prevents the development of hyperactivated motility. Altogether, our findings shed light on the complex control mechanisms of pHi and underscore their importance during human sperm capacitation.This article has an associated First Person interview with the first author of the paper.

pH and male fertility: making sense on pH homeodynamics throughout the male reproductive tract

In the male reproductive tract, ionic equilibrium is essential to maintain normal spermatozoa production and, hence, the reproductive potential. Among the several ions, HCO3- and H+ have a central role, mainly due to their role on pH homeostasis. In the male reproductive tract, the major players in pH regulation and homeodynamics are carbonic anhydrases (CAs), HCO3- membrane transporters (solute carrier 4-SLC4 and solute carrier 26-SLC26 family transporters), Na+-H+ exchangers (NHEs), monocarboxylate transporters (MCTs) and voltage-gated proton channels (Hv1). CAs and these membrane transporters are widely distributed throughout the male reproductive tract, where they play essential roles in the ionic balance of tubular fluids. CAs are the enzymes responsible for the production of HCO3- which is then transported by membrane transporters to ensure the maturation, storage, and capacitation of the spermatozoa. The transport of H+ is carried out by NHEs, Hv1, and MCTs and is essential for the electrochemical balance and for the maintenance of the pH within the physiological limits along the male reproductive tract. Alterations in HCO3- production and transport of ions have been associated with some male reproductive dysfunctions. Herein, we present an up-to-date review on the distribution and role of the main intervenient on pH homeodynamics in the fluids throughout the male reproductive tract. In addition, we discuss their relevance for the establishment of the male reproductive potential.

Making the most of sperm activation responses: experiments with boar spermatozoa and bicarbonate

Attempting to extract useful and reliable information about semen quality and its fertility potential remains a difficult exercise, partly because the sperm heterogeneity within samples often renders simple statistical analyses rather meaningless. In fact, a mean and standard deviation may reflect neither the very fast swimming activities of the most active cells nor the slow and sluggish activities of others. Herein we propose that the information value within semen samples can be maximised if current knowledge about sperm activation mechanisms is exploited before undertaking the measurements. We explain, using boar semen as an example, that estimating and defining relative sperm subpopulation sizes, after activation by bicarbonate, provides a means of quantifying sperm quality. Although such estimates may indeed be related to in vivo fertility, the general approach also suggests potential new avenues that could be exploited for the elaboration of novel in vitro tests for the characterisation of toxic environmental chemicals and, indeed, to reduce the number of animals used in such testing programs.

Molecular Basis of Human Sperm Capacitation

In the early 1950s, Austin and Chang independently described the changes that are required for the sperm to fertilize oocytes in vivo. These changes were originally grouped under name of “capacitation” and were the first step in the development of in vitro fertilization (IVF) in humans. Following these initial and fundamental findings, a remarkable number of observations led to characterization of the molecular steps behind this process. The discovery of certain sperm-specific molecules and the possibility to record ion currents through patch-clamp approaches helped to integrate the initial biochemical observation with the activity of ion channels. This is of particular importance in the male gamete due to the fact that sperm are transcriptionally inactive. Therefore, sperm must control all these changes that occur during their transit through the male and female reproductive tracts by complex signaling cascades that include post-translational modifications. This review is focused on the principal molecular mechanisms that govern human sperm capacitation with particular emphasis on comparing all the reported pieces of evidence with the mouse model.

Male accessory gland inflammation, infertility, and sexual dysfunctions: a practical approach to diagnosis and therapy

The role of urogenital inflammation in causing infertility and sexual dysfunctions has long been a matter of debate in the international scientific literature. The most recent scientific evidences show that male accessory gland infection/inflammation could alter, with various mechanisms, both conventional and biofunctional sperm parameters, and determine worst reproductive outcome. At the same time, the high prevalence of erectile dysfunction and premature ejaculation in patients with male accessory gland infection/inflammation underlines the close link between these diseases and sexual dysfunctions. The aim of this review was to provide the reader the basis for a correct diagnosis of male accessory gland infection/inflammation and a subsequent appropriate therapeutic approach, particularly in patients with infertility and/or sexual dysfunction.

Microbiological investigation in male infertility: a practical overview

The roles of inflammation and/or infection of the male accessory sex glands are very important for the potential effects that these conditions may have on male fertility. The clinical andrologist should be aware of the pathophysiological role of the main determinants of sperm damage when these conditions occur, in particular, seminal leukocytes, oxidative stress and cytokines. In addition, it is important to have a good knowledge of the methodologies to be used in clinical practice. This article summarizes the methods used to look for and to identify the micro-organisms responsible for male urogenital tract infections. These include sperm culture, urine culture, urethral swabbing, the Meares–Stamey test and balanopreputial swabbing. Finally, we discuss the role of human papilloma virus infection in male infertility.

SLC26 anion exchangers in uterine epithelial cells and spermatozoa: clues from the past and hints to the future

The solute carrier 26 (SLC26) family emerges as a distinct class of anion transporters with its members SLC26A3 (Slc26a3) and SLC26A6 (Slc26a6) reported to be electrogenic Cl(-)/HCO3(-) exchangers. While it is known that uterine fluid has high HCO3(-) content and that HCO3(-) is essential for sperm capacitation, the molecular mechanisms underlying the transport of HCO3(-) across uterine epithelial cells and sperm have not been fully investigated. The present review re-examines the results from early reports studying anion transport, finding clues for the involvement of Cl(-)/HCO3(-) anion exchangers in electrogenic HCO3(-) transport across endometrial epithelium. We also summarise recent work on Slc26a3 and Slc26a6 in uterine epithelial cells and sperm, revealing their functional role in working closely with the cystic fibrosis transmembrane conductance regulator (CFTR) for HCO3(-) transport in these cells. The possible involvement of these anion exchangers in other HCO3(-) dependent reproductive processes and their implications for infertility are also discussed.

Transforming growth factor-β1 impairs CFTR-mediated anion secretion across cultured porcine vas deferens epithelial monolayer via the p38 MAPK pathway

The goal of this study was to determine whether transforming growth factor-β1 (TGF-β1) affects epithelial cells lining the vas deferens, an organ that is universally affected in cystic fibrosis male patients. In PVD9902 cells, which are derived from porcine vas deferens epithelium, TGF-β1 exposure significantly reduced short-circuit current (Isc) stimulated by forskolin or a cell membrane-permeant cAMP analog, 8-pCPT-cAMP, suggesting that TGF-β1 affects targets of the cAMP signaling pathway. Electrophysiological results indicated that TGF-β1 reduces the magnitude of current inhibited by cystic fibrosis transmembrane conductance regulator (CFTR) channel blockers. Real-time RT-PCR revealed that TGF-β1 downregulates the abundance of mRNA coding for CFTR, while biotinylation and Western blot showed that TGF-β1 reduces both total CFTR and apical cell surface CFTR abundance. These results suggest that TGF-β1 causes a reduction in CFTR expression, which limits CFTR-mediated anion secretion. TGF-β1-associated attenuation of anion secretion was abrogated by SB431542, a TGF-β1 receptor I inhibitor. Signaling pathway studies showed that the effect of TGF-β1 on Isc was reduced by SB203580, an inhibitor of p38 mitogen-activated protein kinase (MAPK). TGF-β1 exposure also increased the amount of phospho-p38 MAPK substantially. In addition, anisomycin, a p38 MAPK activator, mimicked the effect of TGF-β1, which further suggests that TGF-β1 affects PVD9902 cells through a p38 MAPK pathway. These observations suggest that TGF-β1, via TGF-β1 receptor I and p38 MAPK signaling, reduces CFTR expression to impair CFTR-mediated anion secretion, which would likely compound the effects associated with mild CFTR mutations and ultimately would compromise male fertility.

The physiology of bicarbonate transporters in mammalian reproduction

HCO(3)(-) plays critically important roles during virtually the entire process of reproduction in mammals, including spermatogenesis, sperm capacitation, fertilization, and development of early stage embryos. Therefore, the acid-base balance in the male and female reproductive tracts must be finely modulated. The fluid milieu in the epididymis is acidic, containing very low concentration of HCO(3)(-). In this acidic low HCO(3)(-) environment, mature sperm are rendered quiescent in the epididymis. In contrast, the luminal fluid in the female uterus and oviduct is alkaline, with very high concentration of HCO(3)(-) that is essential for sperm to fulfill fertilization. HCO(3)(-) transporter of solute carrier 4 (SLC4) and SLC26 families represent the major carriers for HCO(3)(-) transport across the plasma membrane. These transporters play critical roles in intracellular pH regulation and transepithelial HCO(3)(-) transport. The physiological roles of these transporters in mammalian reproduction are of fundamental interest to investigators. Here we review recent progress in understanding the expression of HCO(3)(-) transporters in reproductive tract tissues as well as the physiological roles of these transporters in mammalian reproduction.

Male accessory gland infection and sperm parameters (review)

Male accessory gland infection (MAGI) has been identified among those diagnostic categories which have a negative impact on the reproductive function and fertility in males (Rowe et al., World Health Organization Manual for the Standardised Investigation and Diagnosis of the Infertile Couple, Cambridge University Press, Cambridge, 1993). MAGI is a hypernym which groups the following different clinical categories: prostatitis, prostate-vesiculitis and prostate-vesiculo-epididymitis. Some of the characteristics they share are: common diseases, mainly have a chronic course, rarely cause obstruction of the seminal pathways, can have an unpredictable intracanicular spread to one or more sexual accessory glands of the reproductive tract, as well as to one or both sides. In this review, we show that all components involving the inflammatory response (from the agents which first trigger it to each component of the inflammatory response dynamic) can deteriorate conventional and/or non-conventional sperm parameters arising from one or more of the following mechanisms: altered secretory function of the epididymis, seminal vesicles, and prostate which reduce the antioxidant properties or scavenging role of the seminal plasma; deterioration of spermatogenesis; and (unilateral or bilateral) organic or functional sub-obstruction of the seminal tract.

Transmembrane carbonic anhydrase isozymes IX and XII in the female mouse reproductive organs

BACKGROUND

Carbonic anhydrase (CA) classically catalyses the reversible hydration of dissolved CO2 to form bicarbonate ions and protons. The twelve active CA isozymes are thought to regulate a variety of cellular functions including several processes in the reproductive systems.

METHODS

The present study was designed to investigate the expression of transmembrane CAs, CA IX and XII, in the mouse uterus, ovary and placenta. The expression of CA IX and XII was examined by immunoperoxidase staining method and western blotting. CA II and XIII served as positive controls since they are known to be present in the mouse reproductive tract.

RESULTS

The data of our study indicated that CA XII is expressed in the mouse endometrium. Only very faint signal was observed in the corpus luteum of the ovary and the placenta remained mainly negative. CA IX showed weak reaction in the endometrial epithelium, while it was completely absent in the ovary and placenta.

CONCLUSION

The conservation of CA XII expression in both mouse and human endometrium suggests a role for this isozyme in reproductive physiology.

Bicarbonate and its role in mammalian sperm function

This paper deals with the effects of bicarbonate induced signaling pathways on plasma membrane lipid organization and downstream protein signaling, and their role in sperm-egg interactions. It also provides an overview of results that indicate that bicarbonate responses are not related to cell death or apoptosis. The information presented shows that only those sperm cells that have functionally completed maturation in the epididymis are sensitive to bicarbonate whereas immature sperm fail to respond to this physiological challenge. Therefore, it is important to selectively analyze the responsive sperm subpopulations when studying sperm capacitation. Moreover, bicarbonate induced signaling responses differ within the diverse sperm structures (e.g. the tail versus the head). Consequently, dissecting sperm structures and signaling areas from each other deserves more attention in sperm capacitation research. The information discussed was obtained from a variety of mammalian species but the basic bicarbonate-mediated sperm responses are similar in most Eutherian species despite some species to species variations (most notably in kinetics rather than the sequence of events). The objective of the paper is to provide a comparative experimental overview of bicarbonate mediated sperm capacitation in the hope that this information will lead to a better understanding of the complex biochemical nature of the involvement of bicarbonate in mammalian sperm capacitation.

True corrected seminal fructose level: a better marker of the function of seminal vesicles in infertile men

This study was designed to determine if the value obtained after multiplying motile sperm concentration by seminal fructose concentration, named "true corrected fructose", correlates with sperm motility in asthenozoospermic men. Forty-two male partners in infertile couples were studied. Men were treated with 100 mg daily of clomiphene citrate for 5 days. Blood and semen samples were collected before treatment and 24 h after the end of treatment. Serum testosterone, seminal fructose and sperm motility were measured in each subject. Corrected fructose (log. sperm concentration multiplied by seminal fructose), and true corrected fructose (log. motile sperm concentration multiplied by seminal fructose) values were calculated. Prevalence of asthenozoospermia was 42.85% (18 of 42). Prevalence of hypofunction of the seminal vesicles was 9.5% using seminal fructose as a marker; 40.5% using seminal corrected fructose as a marker and 47.6% using true corrected fructose as a marker of seminal vesicle function. Regression analysis showed a better coefficient of determination between true corrected fructose and motile sperm concentration (R2=0.20, p < 0.001) than with corrected fructose (R(2)=0.05, p < 0.1) or fructose concentration (R(2)=0.006, p < 0.5). Asthenozoospermia was observed in 22.7% of subjects with normal function of the seminal vesicles, and in 65% of men with low values of true corrected fructose (z=6.02, p < 0.0001). Multivariate analysis showed that sperm motility grade 3 improved after treatment with clomiphene if true corrected fructose increased (p < 0.002). In those men whose seminal vesicle function improved after clomiphene treatment, a reduction in the prevalence of asthenozoospermia from 50 to 28.6% (z=3.10, p < 0.002) was observed whereas in those whose seminal vesicles did not respond to clomiphene the prevalence of asthenozoospermia was not reduced (z=1.05; p: NS). In conclusion, true corrected fructose measurement relates with sperm motility in cases of asthenozoospermia. Asthenozoospermia improves with clomiphene treatment if seminal vesicle function improves after treatment.

Na+/H+-exchange activity and immunolocalization of NHE3 in rat epididymis

An acidic luminal pH in the epididymis and vas deferens (VD) helps maintain mature sperm in an immotile state during storage. We have previously shown that the majority of proton secretion in the VD is due to the activity of the vacuolar H+-ATPase. Acidification is dependent on luminal sodium in more proximal regions of the epididymis, and we examined the distribution of the Na+/H+ exchanger, NHE3, by immunofluorescence and measured Na+/H+ exchange (NHE) activity in isolated epididymal tubules. NHE3 was detected in the apical pole of nonciliated cells of the efferent ducts and principal cells (PC) of the epididymis. No staining was seen in the distal cauda epididymidis and the VD. Isolated tubules from the distal initial segment (DIS) and proximal cauda epididymidis were perfused in vitro and loaded with the pH-sensitive dye 2',7'-bis(carboxyethyl)-5(6')-carboxyfluorescein. Ethylisopropyl amiloride (EIPA) (50 microM) reduced the initial rate of intracellular pH recovery (dpH(i)/dt), in response to an acute acid load, by 51% and 45% in the DIS and cauda epididymidis, respectively. In the DIS, removal of luminal sodium reduced dpH(i)/dt by 52%. HOE694 (50 microM) inhibited all EIPA-sensitive dpH(i)/dt in the DIS, despite the previously reported absence of NHE2 in this region (Cheng Chew SB, Leung GPH, Leung PY, Tse CM, and Wong PYD, Biol Reprod 62: 755-758, 2000). These data indicate that HOE694- and EIPA-sensitive Na+/H+ exchange may participate, together with the H+-ATPase, in luminal acidification in the male excurrent duct.

Primary structure of a sperm cell anion exchanger and its messenger ribonucleic acid expression during spermatogenesis

Chloride/bicarbonate (Cl-/HCO(3)-) exchangers are a family of proteins (anion exchanger [AE] gene family) that regulate many vital cellular processes such as intracellular pH, cell volume, and Cl- concentration. They may also be involved in the regulation of sperm cell motility and acrosome reaction during fertilization, as these two phenomena are bicarbonate dependent, and we have previously shown that a polypeptide immunologically related to erythrocyte band 3 is expressed in mammalian sperm cells. We have now identified this putative sperm cell anion exchanger as the AE2 isoform of this gene family. First, we determined its complete primary structure from the human testis lambda gt 11 cDNA library. The cloned sequence was found to consist of 3896 base pairs (bp) with an open reading frame of 3726 bp, and to be almost identical to the previously published human genomic AE2 sequence. Only four amino acid disparities were found between these two sequences. Second, our in situ hybridization analyses showed that AE2 mRNA is expressed in developing sperm cells, indicating that the cloned sequence corresponds to the sperm cell AE. Our reverse transcription-polymerase chain reaction analyses suggested further that the expression of AE2 mRNA was variable to some extent during the epithelial cell cycle. Strongest expression was observed at stages VII-XIV except for stage X, i.e., when major structural and morphological changes take place. These results suggest that the full-length AE2 isoform regulates HCO(3)- transport in mature sperm cells and thus their motility in vivo.

Effect of panax notoginseng extracts on inferior sperm motility in vitro

The purpose of this study was to investigate the effects of Panax notoginseng extracts on inferior sperm motility in vitro. Semen samples were collected from 23 patients with sperm motility between 20% and 40%. The sperm count was over 20 x 10(6)/ml in accordance with the World Health Organization standard. 1.0 mg/ml and 2.0 mg/ml of Panax notoginseng extracts including aqueous extract, n-butanol extract, and polysaccharide fraction on sperm motility and progression were evaluated by computer assisted semen analysis. The results demonstrated that sperm motility as well as progression on inferior sperm motility were enhanced at 1 hour and 2 hours after incubation with all three types of extracts.

Severe asthenozoospermia: a structural and functional study

Ejaculates from 25 patients with severe asthenozoospermia (all spermatozoa immotile or only non-progressively motile) were studied to identify individually the cause of impaired motility. Multiple tests were performed, viz. light and electron microscopic studies and sperm function tests. An objective scoring was applied to both the routine and the functional analyses. Three categories of samples were identified: (1) necrozoospermia (n = 9), where sperm viability was very poor; (2) structural tail abnormality as seen by light microscopy (n = 4); and (3) ultrastructural abnormality (n = 12). In the last category, one case showed absence of dynein arms; this was associated with mitochondrial abnormalities. Mitochondrial abnormality with normal tail components was observed in the majority (n = 7) and accessory fibre abnormality in four cases. The scoring system revealed that, functionally, all samples were abnormal whereas routine analysis showed 15 samples to be subnormal and 10 to be abnormal, which indicates the need for functional analysis. Because of the multiple defects seen in these samples, there is a need for a battery of sperm function tests. This study indicates that mitochondrial defects are one of the causes that may account for the loss of sperm motility in the patient population.

Adnexal gland secretion markers in unexplained asthenozoospermia

Prostatic acid phosphatase, prostate-specific antigen, and zinc as markers of prostate, and fructose as marker of seminal vesicles were investigated in the seminal plasma of 35 idiopathic asthenozoospermic and 20 normal subjects to evaluate their relationship with sperm motility. Total seminal plasma levels of the three prostatic markers and, to a lesser extent, total fructose levels were lower in asthenozoospermic patients, and in all the pooled subjects, the same levels were directly correlated with the motility of ejaculated spermatozoa. When the levels of the biochemical markers were expressed as concentrations in seminal plasma, only prostatic acid phosphatase levels remained lower in asthenozoospermic patients and they maintained a direct correlation with sperm motility in all the pooled subjects. The PAP/Zn/Fr (representing the ratio between PAP concentration and free Zn available for spermatozoan uptake) was lower in asthenozoospermic patients and it was also directly related to sperm motility in all the pooled subjects. These data suggest that altered sperm motility is associated with a probable impairment of sex accessory gland function in subjects with idiopathic asthenozoospermia, while prostatic acid phosphatase seems mainly related to sperm motility.

Bicarbonate dependence of cAMP accumulation induced by phorbol esters in hamster spermatozoa

Phorbol esters stimulate cyclic adenosine 3',5'-monophosphate (cAMP) accumulation in hamster spermatozoa under conditions for in vitro capacitation. The 20-50-fold elevation of cAMP levels induced by 1 microM phorbol 12-myristate 13-acetate (PMA) in spermatozoa depends on the presence of sodium bicarbonate in the medium (ED50: 15 mM) and it is independent of extracellular pH. Sodium bicarbonate stimulates adenylate cyclase activity in membrane preparations by 4-fold (ED50: 40 mM). After solubilization, the bicarbonate-sensitive moiety elutes as a single peak of 55 kDa in a gel filtration column. Blockers of bicarbonate chloride antiporters diisothiocyanate stilbene 2,2'-disulfonic acid (DIDS) or acetamido 4'-isothiocyanate stilbene 2,2'-disulfonic acid (SITS) inhibit the bicarbonate dependent PMA effect on cAMP in living spermatozoa (ED50: 100 microM). Maximal (85%) inhibition in cAMP accumulation is observed at 1 mM. Motility is inhibited only at high concentrations of the blockers. Pretreatment of living cells with 1 mM DIDS does not affect membrane adenylate cyclase activity which remains responsive to bicarbonate. These results suggest that controlled transport of bicarbonate through the sperm plasma membrane could be associated to the regulation of cAMP synthesis.

Effects of a membrane-bound trypsin-like proteinase and seminal proteinase inhibitors on the bicarbonate-sensitive adenylate cyclase in porcine sperm plasma membranes

Plasma membranes were purified from flagella of porcine cauda epididymal sperm and proteolytic regulation of bicarbonate-sensitive adenylate cyclase was studied. It was found that the epididymal sperm plasma membrane contained a trypsin-like proteinase which inactivated adenylate cyclase. Bicarbonate activates adenylate cyclase as reported previously, but, at the same time, the anions enhance the inactivation of the enzyme by the membrane-bound trypsin-like proteinase. This phenomenon is not due to the direct activation of the proteinase, but closely related to the activation of adenylate cyclase by bicarbonate. It was also found that seminal proteinase inhibitors blocked the inactivation of adenylate cyclase and maintained the bicarbonate activation of the enzyme at high level. Actually, bicarbonate keeps adenylate cyclase fully active in ejaculated sperm, because membrane-bound proteinase is completely inhibited by the seminal proteinase inhibitors. These results suggest that the interactions between membrane-bound proteinase and seminal proteinase inhibitor are involved in the regulation of the bicarbonate-sensitive adenylate cyclase system.

The enhancing effects of anion channel blockers on sperm activation by bicarbonate

We found that anion channel blockers such as phosphotungstate and 4,4'-diisothiocyanatostilbene-2,2'-disulfonate (DIDS) enhanced HCO3(-)-induced activation on porcine epididymal sperm. In the presence of these compounds, HCO3- increased the motility, respiration rate and especially the cAMP content of the sperm to a greater extent than did HCO3- alone. The enhancing effects were not observed in the absence of HCO3-, but were evident when the concentration of HCO3- was low. These compounds did not significantly alter the intracellular pH and did inhibit the adenylate cyclase activity of the sperm plasma membrane. When these compounds were added to sperm homogenate with ATP, the cAMP formed was reduced compared to the control. In addition, these compounds inhibited both the SO4(2-) influx and efflux of the sperm. From these results, we conclude that the anion channel blockers tested principally inhibit the efflux of endogenous HCO3- derived from metabolic CO2, so that HCO3- accumulates intracellularly and stimulates the adenylate cyclase of the sperm.

The secretory activity of the seminal vesicles and its relationship to sperm motility: effects of infection in the male reproductive tract

In 146 males aged between 20 years and 40 years attending an infertility service, the secretory activity of the seminal vesicles was assessed by measurement of corrected seminal fructose concentration. This value was related to the presence of a positive semen culture, other evidence of inflammatory processes in the reproductive tract and sperm motility. Only 48% of subjects with a positive semen culture showed evidence of inflammation in the reproductive tract, as assessed by the presence of more than 20 white blood cells per high power field, and greater than 10% spermagglutination in the ejaculate. There was a relationship between the inflammatory process, hypofunction of the seminal vesicles and poor sperm motility. When the semen culture was positive but there was no evidence of inflammation neither seminal vesicle function nor sperm motility was affected. When the semen culture was negative, i.e. no evidence of inflammation and the subjects were asthenozoospermic, the corrected fructose levels were normal. It is proposed that in these conditions the cause of asthenozoospermia may be factors other than accessory sex organ dysfunction. In conclusion, there was no close relationship between the bacteriological results and evidence of inflammation of the accessory glands. A positive semen culture was related to lower levels of corrected fructose (hypofunction of the seminal vesicles) when the positive sperm culture was associated with inflammation of the reproductive tract and asthenozoospermia.

Seminal prolactin and its relationship to sperm motility in men

Semen assessment and levels of serum and seminal plasma prolactin (PRL) were determined in 81 men. In subjects with both normal sperm concentrations and normal sperm motility, the levels of serum and seminal plasma PRL were 14.7 +/- 1.48 and 10.0 +/- 1.05 ng/ml (mean +/- standard error of the mean, SEM, P less than 0.05), respectively. This difference is not observed either in subjects with polyzoospermia with normal sperm motility, or in those with oligozoospermia. Serum PRL was higher in azoospermia and also in subjects with lower levels of seminal citric acid. Seminal plasma PRL was directly related to sperm motility (r = 0.70, P less than 0.01) and inversely related to sperm concentration (r = -0.42 P less than 0.05). Seminal PRL was increased in subjects with higher levels of seminal citric acid and decreased in subjects with lower levels of corrected seminal fructose. Serum and seminal plasma PRL did not change significantly in subjects with different concentrations of serum testosterone.

Functional structure and ultrastructure of seminal vesicles

The function of the seminal vesicles in animals and man is under androgen control. The use of a new marker of the seminal vesicle function, termed corrected fructose, demonstrates an association between serum testosterone levels and seminal corrected fructose levels. The human seminal vesicles secrete a variety of products, and there is good evidence of a close relationship between functions of the seminal vesicles and sperm motility. Some of their products of secretion, such as potassium, bicarbonate, prostaglandins, and prolactin, directly stimulate the motility of the sperm through actions at the level of the mechanisms of production of the energy necessary for the motion. Several constituents are secreted by the seminal vesicles, some of which have no specific functions.

Decrease in bicarbonate transport activities during epididymal maturation of porcine sperm

Kinetic studies of [14C]HCO3- and [35S]SO4(2-) transport show the existence of a common transport system for the two anions on the plasma membranes of porcine epididymal sperm. Km value for bicarbonate (8.3mM) is within the range of physiological concentration of bicarbonate. The anion transport activity is dependent on the temperature but independent of co-existence of Na+. Its pH dependency and sensitivity to the several anion transport inhibitors are similar to those observed in erythrocyte. Anion transport activity decreases during sperm maturation in epididymis.

Identification of andrologic patient groups by cluster analysis

To test the validity of the current andrologic classification system, we performed cluster analysis in 317 andrologic patients involuntarily barren for more than 1 year. For cluster analysis, the spermatologic parameters sperm density, motility, and morphologic features were used since only these parameters contributed significantly to group identification, as revealed by stepwise discriminant function analysis. The optimal number clusters determined by calculation of the variance criterion was five. The resulting five groups partly correspond to the prevailing descriptive classification system as far as the extreme groups of "high-grade oligoteratoasthenozoospermia" and "polyzoospermia" are concerned. Surprisingly, cluster analysis distinguished between two groups of normozoospermia that differed in their mean sperm density. Cluster analysis may prove to become a powerful tool for andrologic classification.

Investigation of the cause of low sperm motility in asthenozoospermic patients by multiple quantitative tests

Multiple tests were done on the ejaculates of 10 asthenozoospermic patients and nine healthy normozoospermic volunteers in an attempt to identify individually the cause of low sperm motility in these patients. Possible defects in the sperm plasma membrane and the motility apparatus of sperm, and in epididymal function affecting the development of motility, were investigated. The presence of seminal sperm antibodies or any motility-inhibiting factors in the seminal plasma that could be removed by washing were also tested. Each test was positive in only one or two patients but axonemal dysfunction was identified in nine patients. Removal of seminal plasma from asthenozoospermic samples did not improve sperm motility to any greater extent than with donor ejaculates, and the motile sperm of these patients exhibited characteristics mostly similar to those of donors under various incubation conditions. Selection procedures are, therefore, required to obtain samples of good quality sperm from such asthenozoospermic ejaculates.

Corrected seminal fructose levels: index of secretory activity of seminal vesicles

Seminal fructose, sperm count, and sperm motility were measured in 340 men attending an infertility clinic. Seminal fructose correlates negatively with sperm count but not with sperm motility. The best correlation between sperm count and seminal fructose was obtained using the logarithm (log) of sperm count. When seminal fructose was multiplied by the log of sperm count obtaining a value named "corrected fructose," the correlation with sperm count disappeared, and there was positive correlation between corrected seminal fructose and sperm motility. Therefore, corrected seminal fructose level was significantly lower in asthenospermic than in normomotile subjects, irrespective of the sperm count. Corrected seminal fructose, but not seminal fructose levels, was lowered in subjects with either low levels of serum testosterone (less than 3 ng/ml) or evidence of an obstructive process in the reproductive tract. In both situations sperm motility was also reduced. The corrected fructose level was not affected by the presence of varicocele, hyperprolactinemia, or hyperserotoninemia. Measurement of corrected seminal fructose rather than seminal fructose may be a useful marker of the secretory activity of the seminal vesicles.

Effect of urea and detergents on the ability of human spermatozoa to penetrate zona-free hamster oocytes

Washing of human spermatozoa with either BWW alone or with the same buffer containing 0.1 M urea, 0.005% SDS or 0.001% NP40 affected the penetration ability of the gametes into zona-free hamster oocytes to various degrees. In contrast, human spermatozoa washed with BWW buffer containing 0.3 M urea had an increased ability to fuse with the heterologous oocytes when compared to controls capacitated with BWW/BSA. Moreover, the presence or absence of BSA in the insemination medium did not further modify this enhanced penetration pattern. The BWW, BWW/0.1 M urea and BWW/SDS treatments apparently mimicked some of the in vitro capacitation properties of albumin-containing media; the BWW/0.3 M urea treatment overpowered the capacitation and acrosomal reaction extent obtained with BWW+BSA. In all samples the motility of the spermatozoa washed with BWW buffer alone or containing various additives (but no albumin) was significantly decreased if compared to the motility of semen samples washed with albumin containing media. However, each sperm sample behaved differently when exposed to a given buffer.

Stimulation of partially purified adenylate cyclase from bull sperm by bicarbonate

Solubilized and partially purified adenylate cyclase from bull sperm was found to be specifically activated (up to 6-fold) by sodium bicarbonate (NaHCO3) and to a lesser extent by NaNO3. Other sodium salts were either ineffective (e.g. NaCOOH) or inhibitory (e.g. NaHSO3, NaHSO4 and Na2B4O7). Stimulation by NaHCO3 was dose-dependent in the range of 0-40 mM and was greater when enzyme activity was assayed in the presence of magnesium as compared with manganese ions. Bicarbonate seems to affect maximal enzyme velocity (Vmax) and has no effect on the Km of adenylate cyclase for Mn-ATP. Stimulation of adenylate cyclase by NaHCO3 coincided with the elution pattern of the enzyme as recorded following chromatography on DEAE-cellulose or gel filtration on BioGel P-100. These results suggest that in the course of stimulation of sperm adenylate cyclase, bicarbonate is likely to interact directly with the enzyme. Furthermore, this intrinsic and unique property of sperm adenylate cyclase may explain results reported by others on the stimulation of cAMP production by bicarbonate in intact and broken sperm preparations and suggest a biochemical basis for enhanced sperm motility associated with high bicarbonate concentrations.

The activating effects of bicarbonate on sperm motility and respiration at ejaculation

Mature porcine sperm preserved in the cauda epididymis are quiescent. At ejaculation, they are mixed with the seminal vesicle fluid containing HCO3- and are rapidly activated. The role of HCO3- on the sperm activation process at ejaculation was studied in vitro. HCO3- quickly increased the motility, respiration rate and cAMP content of the porcine epididymal sperm. The extent of activation was proportional to the pCO2 in the medium. The activating effect of HCO3- on the motility was observed even in the absence of fructose as well as in the presence of KCN. 8-Bromoadenosine 3',5'-cyclic monophosphate and theophylline showed similar activating effects to that of HCO3-. However, HCO3(-)-free seminal plasma, Ca2+, amino acids, intermediates of the Krebs cycle, substrates of respiration and increases in the intracellular pH, extracellular pH or ionic strength of the medium had no effect. Fructose sustained the active state of the sperm and gradually increased both the motility and respiration rate when the dose of HCO3- was low. The anion channel blocker enhanced the activating effect of HCO3-. These results suggest that, upon ejaculation, HCO3- is a unique activator in vivo which makes the quiescent sperm motile via the HCO3(-)-adenylate cyclase-cAMP system, to which an endogenous HCO3- derived from metabolic CO2 may be related.

Biochemical correlates of asthenozoospermia: a lesion at the level of the sperm adenylyl cyclase

Studies of the adenylyl cyclase in spermatozoa from 10 asthenozoospermic and 10 normal men revealed major differences with regard to the activation of the enzyme by various drugs and metal ions. While the response to acetate ions was normal, activation of the enzyme by forskolin and the GTP analogue [Gpp(NH)p] was uniformly impaired. In addition, in 4 of the patients the ratios of the Mn2+- and Mg2+-dependent activities of the enzyme were significantly higher than normal, suggesting a delay in the transformation of the enzymes catalytic unit from the soluble to the membrane-bound form. No differences could be recorded in a variety of seminal plasma components including prostatic acid phosphatase, citric acid, zinc, putrescine, spermidine, spermine, fructose, prostaglandin E, and testosterone. Furthermore, the DNA fluorescence patterns of the spermatozoa measured by flow cytometry were within the range of control variations, suggesting that chromatin condensation, and thus nuclear maturation, proceeded normally. The study suggests that a lesion in the adenylyl cyclase system of the germ cells may explain at least some of the motility disturbances seen in infertile males.