Semen quality and presence of cytokines in seminal fluid of bull ejaculates

Molecular Determinants in Pig Semen: Verified Protocols for Cytokine Detection and Quantification

Cytokines, a family of pleiotropic regulatory proteins, are critical mediators of both innate and adaptive immune responses. Growing evidence supports the involvement of cytokines in several physiological and pathological processes, including those related to reproduction. Semen contains a broad panel of cytokines, which play a key role in several reproductive processes, influencing both sperm function and modulating the uterine immune-cytokine network, essential for successful embryo development. In the last years, the assessment of a wide repertoire of seminal cytokines has been used as valuable biomarkers for several physio- and pathological conditions in mammalian species, including fertility disorders.In this chapter, we will describe several methods and protocols for the detection and/or quantification of cytokines in semen samples (seminal plasma and sperm cells), using the pig as an animal model. First, we will describe a protocol for the quantification of cytokine mRNA by real-time quantitative PCR and for in situ detection of cytokine production by immunohistochemistry in sperm cells. In addition, we will describe methods for quantification of cytokines in seminal plasma samples by enzyme-linked immunosorbent assay (ELISA) as well as by novel cytokine bead arrays (Luminex®).

Evaluation of the relationships between oxidative stress, inflammation, hormonal status and sperm parameters in rats: Canonical correlation analysis

Many endocrine or non-endocrine factors are involved in sperm production. Although reproductive hormones are very important for the initiation and maintenance of spermatogenesis, other factors, such as inflammation and oxidative stress, affect spermatogenesis. The aim of this study is to evaluate the relationships between sperm parameters and hormones, oxidative stress, and inflammation status. We conducted this study on 40 rats. Sperm parameters (motility, abnormal sperm rate, and dead sperm rate), oxidative stress (malondialdehyde, glutathione, glutathione peroxidase, and catalase), inflammation (NF-κβ, TNF-α, IL-1β, IL-6, and IL-10), and hormone parameters (follicle-stimulating hormone, luteinizing hormone, testosterone, melatonin, and corticosterone) were determined. Relationships between mentioned parameters were investigated by canonical correlation analysis. Canonical correlation coefficients for these data sets (sperm-oxidative stress, sperm-inflammation, and sperm-hormone parameters) were found to be strongly significant (rc= 0.875, p<0.001; rc= 0.868, p<0.001; rc= 0.886, p<0.001, respectively). The rate of explanation of oxidative stress, inflammation parameters and hormones by sperm parameters was 61.80 %, 56.10 % and 63.90 %, respectively. Canonical correlation analysis results have revealed that dead sperm rate is mostly related to nuclear factor-kappa beta (NF-κβ), catalase, and corticosterone. CCA, which has taken into account the multiple relationships, has revealed that multidimensional evaluation of data sets can provide important and innovative information to researchers for the assessment of relationships between sperm, oxidative stress, inflammation, and hormone parameters.

Extracellular vesicles would be involved in the release and delivery of seminal TGF-β isoforms in pigs

Introduction

Pig seminal plasma (SP) is rich in active forms of all three isoforms (1-3) of transforming growth factor β (TGF-β), a chemokine modulatory of the immune environment in the female genital tract once semen is delivered during mating or artificial insemination (AI). The present study aimed to examine how TGF-βs are secreted by the epithelium of the male reproductive tract and how they are transported in semen, emphasizing the interplay with seminal extracellular vesicles (sEVs).

Methods

Source of TGF-βs was examined by immunohistochemistry in testis, epididymis, and accessory sex glands, by immunocytochemistry in ejaculated spermatozoa, and by Luminex xMAP® technology in SP and sEVs retrieved from healthy, fertile male pigs used as breeders in AI programs.

Results

All three TGF-β isoforms were expressed in all reproductive tissues explored and would be released into ductal lumen either in soluble form or associated with sEVs. Ejaculated spermatozoa expressed all three TGF-β isoforms, both inside and outside, probably the outer one associated with membrane-bound sEVs. The results confirmed that pig SP contains all three TGF-β isoforms and demonstrated that a substantial portion of them is associated with sEVs.

Discussion

Seminal EVs would be involved in the cellular secretion of the active forms of seminal TGF-β isoforms and in their safe transport from the male to the female reproductive tract.

Seminal Bacterioflora of Two Rooster Lines: Characterization, Antibiotic Resistance Patterns and Possible Impact on Semen Quality

This study aimed to characterize the bacterial profiles and their association with selected semen quality traits among two chicken breeds. Thirty Lohmann Brown and thirty ROSS 308 roosters were selected for semen quality estimation, including sperm motility, membrane and acrosome integrity, mitochondrial activity, and DNA fragmentation. The oxidative profile of the semen, including the production of reactive oxygen species (ROS), antioxidant capacity, protein, and lipid oxidation, were assessed as well. Moreover, the levels of pro-inflammatory cytokines, including tumor necrosis factor alpha (TNF-α), interleukins 1 and 6 (IL-1, IL-6) and C-reactive protein, as well as the concentrations of selected antibacterial proteins (cathelicidin, β-defensin and lysozyme) in the seminal plasma were evaluated with the enzyme-linked immunosorbent assay. The prevailing bacterial genera identified by the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry were Citrobacter spp., Enterococcus spp., Escherichia spp. and Staphylococcus spp. While the bacterial load was significantly higher in the ROSS 308 line (p < 0.05), a higher number of potentially uropathogenic bacteria was found in the Lohmann Brown roosters. Antimicrobial susceptibility tests revealed a substantial resistance of randomly selected bacterial strains, particularly to ampicillin, tetracycline, chloramphenicol, and tobramycin. Furthermore, Lohmann Brown ejaculates containing an increased proportion of Escherichia coli presented with significantly (p < 0.05) elevated levels of TNF-α and IL-6, as well as ROS overproduction and lipid peroxidation. Inversely, significantly (p < 0.05) higher levels of β-defensin and lysozyme were found in the semen collected from the ROSS 308 roosters, which was characterized by a higher quality in comparison to the Lohmann Brown roosters. In conclusion, we emphasize the criticality of bacteriospermia in the poultry industry and highlight the need to include a more complex microbiological screening of semen samples designated for artificial insemination.

Unraveling the harmful effect of oxidative stress on male fertility: A mechanistic insight

Male infertility is a widely debated issue that affects males globally. There are several mechanisms involved. Oxidative stress is accepted to be the main contributing factor, with sperm quality and quantity affected by the overproduction of free radicals. Excess reactive oxygen species (ROS) cannot be controlled by the antioxidant system and, thus, potentially impact male fertility and hamper sperm quality parameters. Mitochondria are the driving force of sperm motility; irregularities in their function may lead to apoptosis, alterations to signaling pathway function, and, ultimately, compromised fertility. Moreover, it has been observed that the prevalence of inflammation may arrest sperm function and the production of cytokines triggered by the overproduction of ROS. Further, oxidative stress interacts with seminal plasma proteomes that influence male fertility. Enhanced ROS production disturbs the cellular constituents, particularly DNA, and sperms are unable to impregnate the ovum. Here, we review the latest information to better understand the relationship between oxidative stress and male infertility, the role of mitochondria, the cellular response, inflammation and fertility, and the interaction of seminal plasma proteomes with oxidative stress, as well as highlight the influence of oxidative stress on hormones; collectively, all of these factors are assumed to be important for the regulation of male infertility. This article may help improve our understanding of male infertility and the strategies to prevent it.

Identification of genomic regions associated with total and progressive sperm motility in Italian Holstein bulls

Sperm motility is directly related to the ability of sperm to move through the female reproductive tract to reach the ovum. Sperm motility is a complex trait that is influenced by environmental and genetic factors and is associated with male fertility, oocyte penetration rate, and reproductive success of cattle. In this study we carried out a GWAS in Italian Holstein bulls to identify candidate regions and genes associated with variations in progressive and total motility (PM and TM, respectively). After quality control, the final data set consisted of 5,960 records from 949 bulls having semen collected in 10 artificial insemination stations and genotyped at 412,737 SNPs (call rate >95%; minor allele frequency >5%). (Co)variance components were estimated using single trait mixed models, and associations between SNPs and phenotypes were assessed using a genomic BLUP approach. Ten windows that explained the greatest percentage of genetic variance were located on Bos taurus autosomes 1, 2, 4, 6, 7, 23, and 26 for TM and Bos taurus autosomes 1, 2, 4, 6, 8, 16, 23, and 26 for PM. A total of 150 genes for TM and 72 genes for PM were identified within these genomic regions. Gene Ontology enrichment analyses identified significant Gene Ontology terms involved with energy homeostasis, membrane functions, sperm-egg interactions, protection against oxidative stress, olfactory receptors, and immune system. There was significant enrichment of quantitative trait loci for fertility, calving ease, immune response, feed intake, and carcass weight within the candidate windows. These results contribute to understanding the architecture of the genetic control of sperm motility and may aid in the development of strategies to identify subfertile bulls and improve reproductive success.

Evaluating the therapeutic effect and toxicity of theophylline in infertile men with asthenoteratozoospermia: a double-blind, randomized clinical trial study

Theophylline as a cyclic adenosine monophosphate (cAMP) phosphodiesterase inhibitor (cAMP-PDEI) elevates cAMP levels. We aimed to evaluate the therapeutic effect and toxicity of theophylline on the sperm parameters, oxidative stress (OS), and inflammation in asthenoteratozoospermic men. Sixty asthenoteratozoospermic patients were divided into groups of placebo and theophylline (200 mg/day). After 3 months of oral treatment, sperm parameters, viability, and DNA fragmentation were analyzed by the CASA system, eosin nigrosin staining, sperm DNA fragmentation kit, respectively. The seminal plasma level of reactive oxygen species (ROS) of neat semen samples, malondialdehyde (MDA), total antioxidant capacity (TAC), tumor necrosis factor alpha (TNF-α), and interleukin-10 (IL-10) was assessed. Data were analyzed statistically using the independent samples t-test and the paired t-test and the means were considered significantly different at p < 0.05. Sperm motility, viability, and the number of sperms with normal morphology and the seminal plasma level of TAC and IL-10 and also sperm DNA fragmentation increased significantly in the theophylline group compared to the placebo. The MDA, TNF-α, and ROS levels decreased significantly in the theophylline group compared to the placebo. Theophylline improved sperm parameters, reduced OS and inflammation, but also created genotoxicity and increased sperm DNA fragmentation. Therefore, to benefit from the desired effects of theophylline and inhibit the toxicity of it in the treatment of men with asthenoteratozoospermia, it is suggested to be used simultaneously with another antioxidant to protect sperm DNA from fragmentation.

Local action of cytokines and immune cells in communication between the conceptus and uterus during the critical period of early embryo development, attachment and implantation - Implications for embryo survival in cattle: A review

Early embryo development, implantation and pregnancy involve a complex dialogue between the embryo and mother. In cattle this dialogue starts as early as days 3-4 when the embryo is still in the oviduct, and it continues to implantation. Immunological processes involving cytokines, mast cells and macrophages form an important part of this dialogue. Amongst the cytokines, interleukin-6 (Il-6) and leukemia inhibitory factor (LIF) are secreted by both the embryo and uterine endometrium and form part of an ongoing and reciprocating dialogue. Mast cells and macrophages populate the uterine endometrium during embryo development and are involved in achieving the correct balance between inflammatory and anti-inflammatory reactions at the uterus that are associated with embryo attachment and implantation. Embryo loss is the major cause of reproductive wastage in cattle, and livestock generally. A deeper understanding of immunological processes during early embryo development will help to achieve the next step change in the efficiency of natural and assisted breeding.

Seminal Plasma Cytokines Are Predictive of the Outcome of Boar Sperm Preservation

Background: Boar seminal plasma is rich in cytokines, which could influence the capability of spermatozoa to tolerate preservation. Objectives: To evaluate the involvement of boar seminal plasma cytokines in the changes experienced by boar spermatozoa during their storage, either in liquid or frozen state. Materials and Methods: In two separated experiments, semen samples from healthy and fertile boars were split in two aliquots, one centrifuged twice (1,500 ×g for 10 min) to harvest seminal plasma, whereas the other was either commercially extended (3 × 10⁷ sperm/mL) and liquid-stored at 17°C during 144 h (n = 28, Experiment 1) or frozen-thawed using a standard 0.5 mL protocol (n = 27, Experiment 2). Sixteen cytokines were quantified using Luminex xMAP®. Sperm attributes (CASA-evaluated total and progressive motility; flow cytometry-evaluated sperm viability, production of intracellular H₂O₂ and O 2 • - and levels of lipid peroxidation in viable spermatozoa) were evaluated either at 0, 72, or 144 h of liquid storage (Experiment 1) or before freezing and at 30- and 150-min post-thawing (Experiment 2). Results: Multiple linear regression models, with Bayesian approach for variable selection, revealed that the anti-inflammatory TGF-β2, TGF-β3, IL-1Ra, and IL-4 and the pro-inflammatory IL-8 and IL-18, predicted changes in sperm motility for liquid-stored semen while the anti-inflammatory IFN-γ was included in the models predicting changes in all sperm attributes for cryopreserved semen. Conclusion: Specific boar seminal plasma cytokines would contribute to modulate the structural and metabolic changes shown by spermatozoa during preservation, either in liquid or frozen state.

β-Defensins: Farming the Microbiome for Homeostasis and Health

Diverse commensal populations are now regarded as key to physiological homeostasis and protection against disease. Although bacteria are the most abundant component of microbiomes, and the most intensively studied, the microbiome also consists of viral, fungal, archael, and protozoan communities, about which comparatively little is known. Host-defense peptides (HDPs), originally described as antimicrobial, now have renewed significance as curators of the pervasive microbial loads required to maintain homeostasis and manage microbiome diversity. Harnessing HDP biology to transition away from non-selective, antibiotic-mediated treatments for clearance of microbes is a new paradigm, particularly in veterinary medicine. One family of evolutionarily conserved HDPs, β-defensins which are produced in diverse combinations by epithelial and immune cell populations, are multifunctional cationic peptides which manage the cross-talk between host and microbes and maintain a healthy yet dynamic equilibrium across mucosal systems. They are therefore key gatekeepers to the oral, respiratory, reproductive and enteric tissues, preventing pathogen-associated inflammation and disease and maintaining physiological normality. Expansions in the number of genes encoding these natural antibiotics have been described in the genomes of some species, the functional significance of which has only recently being appreciated. β-defensin expression has been documented pre-birth and disruptions in their regulation may play a role in maladaptive neonatal immune programming, thereby contributing to subsequent disease susceptibility. Here we review recent evidence supporting a critical role for β-defensins as farmers of the pervasive and complex prokaryotic ecosystems that occupy all body surfaces and cavities. We also share some new perspectives on the role of β-defensins as sensors of homeostasis and the immune vanguard particularly at sites of immunological privilege where inflammation is attenuated.

The Female Post-Mating Response Requires Genes Expressed in the Secondary Cells of the Male Accessory Gland in Drosophila melanogaster

Seminal proteins from the Drosophila male accessory gland induce post-mating responses (PMR) in females. The PMR comprise behavioral and physiological changes that include increased egg laying, decreased receptivity to courting males, and changes in the storage and use of sperm. Many of these changes are induced by a "sex peptide" (SP) and are maintained by SP's binding to, and slow release from, sperm. The accessory gland contains two secretory cell types with distinct morphological and developmental characteristics. Products of these "main" and "secondary" cells work interdependently to induce and maintain the PMR. To identify individual genes needed for the morphology and function of secondary cells, we studied iab-6(cocu) males, whose secondary cells have abnormal morphology and fail to provide products to maintain the PMR. By RNA-seq, we identified 77 genes that are downregulated by a factor of >5× in iab-6(cocu) males. By functional assays and microscopy, we tested 20 candidate genes and found that at least 9 are required for normal storage and release of SP in mated females. Knockdown of each of these 9 genes consequently leads to a reduction in egg laying and an increase in receptivity over time, confirming a role for the secondary cells in maintaining the long-term PMR. Interestingly, only 1 of the 9 genes, CG3349, encodes a previously reported seminal fluid protein (Sfp), suggesting that secondary cells may perform essential functions beyond the production and modification of known Sfps. At least 3 of the 9 genes also regulate the size and/or abundance of secondary cell vacuoles, suggesting that the vacuoles' contents may be important for the machinery used to maintain the PMR.

Cytokines in the blood and semen of infertile patients

Cytokines have been important mediators of the immunity and can be involved in numerous processes in the male genital tract including acting as immunomodulatory elements within the male gonad.

The aims of this study were: 1) to detect pro- and anti-inflammatory cytokine levels in the control group and subgroups of infertile men; and 2) to set up the practical recommendations concerning determination of cytokine levels for the male infertility diagnosis.

Observations were performed in a group of 82 men: healthy controls (n = 27) and infertile patients (n = 55). The male infertility group was further subdivided into patients with: varicocele (n = 22), idiopathic infertility (n = 13) and partners of couples with recurrent spontaneous abortion (RSA; n = 20). Semen analysis was determined following WHO criteria. The cytokine interleukin 1β (IL-1β), IL-6, IL-10, IL-18; tumor necrosis factor α (TNF-α), interferon g (IFN-g) and transforming growth factor β1 (TGF-β1) contents in serum and seminal plasma were determined by quantitative ELISA.

An interesting marker of male infertility appears to be TGF-β1 (blood) significantly elevated in idiopathically infertile males and in the RSA group. Besides elevated TGF-β1 in a group of idiopathic infertility significantly elevated IL-10, IL-18, IFN-g (blood) and statistically decreased IL-1β while increased IFN-g were revealed in seminal plasma compared to healthy controls.

We may postulate novel cytokine micropatterns for patients with different background of infertility. Therefore, circulating cytokines: IL-1β, IL-10, IL-18, TGF-β1, IFN-g and IL-1β, IFN-g and TGF-β1 in seminal plasma should be extended in evaluation of specific types of male infertility.

Value of semen parameters, with special reference to TNF-α, in predicting the quality of boar semen after short-term storage

The aim of this study was to address the question whether changes in boar semen quality after short-term storage could be predicted on the basis of standard semen parameters and TNF-α level determined on the day of semen collection under commercial conditions. Progressive motility showed the highest positive correlation with morphology on day 0 of collection, and progressive motility on day 3 (P < 0.05) showed a negative correlation with acrosome abnormalities (P < 0.05). According to the area under receiver operating characteristics (ROC) curves (AUCs), progressive motility could also be used in predicting semen quality after 3 days of storage (AUC > 0.5; P < 0.05). TNF-α in seminal plasma is the only parameter measured on day 0 to show a significant correlation with the percentage of viable spermatozoa after 3 days of semen storage (r = 0.495, P < 0.05). ROC analysis shows that TNF-α level is helpful in discriminating viability outcome after semen storage (AUC = 0.94, P < 0.001). We can predict with 92.35% certainty that fresh semen samples with more than 150 pg/ml of TNF-α in the seminal plasma will retain more than 85% of viable spermatozoa after 3 days of storage. Thus, TNF-α can contribute to predicting the quality of short-term stored semen.

Localization of tumor necrosis factor in the canine testis, epididymis and spermatozoa

Tumor necrosis factor (TNF), formerly known as Tumor necrosis factor alpha is now regarded as a natural component of the mammalian seminal plasma (SP). Although not completely clarified, its functions in the SP have been associated with paradoxal roles, such as sperm survival in the female genital tract, while at high levels negatively affect sperm survival and fertility potential. Recently, it has been discovered that canine inseminated spermatozoa display a strong immunoreaction for TNF when lining the female endometrium. As a continuation of this finding, the present work aimed at documenting TNF localization in the canine testes and epididymis and in freshly ejaculated spermatozoa (SPZ) through immunohisto- or cytochemistry. Immunoreaction for TNF was found in all samples used. In the dog testis, TNF immunoexpression was limited to the seminiferous tubules, where late round spermatids (SPD) showed weak intensity of immunostaining, while elongating and elongated SPD evidenced moderate and the residual bodies a strong intensity. In the epididymis, a gradual progressive increase of TNF immunolabelling was found throughout the epididymal regions, ranging from a weak intensity at the caput epididymis to a moderate intensity at the cauda. TNF immunolabelling was found in mature SPZ during the epididymal transit and also in freshly ejaculated SPZ, which showed a strong midpiece immunolabelling. Data presented here provide important information on expression of TNF in spermatozoa, which is acquired by the SPZ during their formation at the testis. It further provides the basis for subsequent studies on the physiological importance of cytokines in sperm function.

Cetrorelix suppresses the preovulatory LH surge and ovulation induced by ovulation-inducing factor (OIF) present in llama seminal plasma

BACKGROUND

The purpose of the study was to determine if the effect of llama OIF on LH secretion is mediated by stimulation of the hypothalamus or pituitary gland.

METHODS

Using a 2-by-2 factorial design to examine the effects of OIF vs GnRH with or without a GnRH antagonist, llamas with a growing ovarian follicle greater than or equal to 8 mm were assigned randomly to four groups (n = 7 per group) and a) pre-treated with 1.5 mg of GnRH antagonist (cetrorelix acetate) followed by 1 mg of purified llama OIF, b) pre-treated with 1.5 mg of cetrorelix followed by 50 micrograms of GnRH, c) pre-treated with a placebo (2 ml of saline) followed by 1 mg of purified llama OIF or d) pre-treated with a placebo (2 ml of saline) followed by 50 micrograms of GnRH. Pre-treatment with cetrorelix or saline was given as a single slow intravenous dose 2 hours before intramuscular administration of either GnRH or OIF. Blood samples for LH measurement were taken every 15 minutes from 1.5 hours before to 8 hours after treatment. The ovaries were examined by ultrasonography to detect ovulation and CL formation. Blood samples for progesterone measurement were taken every-other-day from Day 0 (day of treatment) to Day 16.

RESULTS

Ovulation rate was not different (P = 0.89) between placebo+GnRH (86%) and placebo+OIF groups (100%); however, no ovulations were detected in llamas pre-treated with cetrorelix. Plasma LH concentrations surged (P < 0.01) after treatment in both placebo+OIF and placebo+GnRH groups, but not in the cetrorelix groups. Maximum plasma LH concentrations and CL diameter profiles did not differ between the placebo-treated groups, but plasma progesterone concentrations were higher (P < 0.05), on days 6, 8 and 12 after treatment, in the OIF- vs GnRH-treated group.

CONCLUSION

Cetrorelix (GnRH antagonist) inhibited the preovulatory LH surge induced by OIF in llamas suggesting that LH secretion is modulated by a direct or indirect effect of OIF on GnRH neurons in the hypothalamus.

ICAM1 and fibrinogen-γ are increased in uterine epithelial cells at the time of implantation in rats

Uterine epithelial cells transform into a receptive state to adhere to an implanting blastocyst. Part of this transformation includes the apical concentration of cell adhesion molecules at the time of implantation. This study, for the first time, investigates the expression of ICAM1 and fibrinogen-γ (FGG) in uterine epithelial cells during normal pregnancy, pseudopregnancy and in hormone-treated rats. An increase (P < 0.05) in ICAM1 was seen at the apical membrane of uterine epithelial cells at the time of implantation compared with day 1 of pregnancy. ICAM1 was also increased (P < 0.05) on day 6 of pseudopregnancy as well as in ovariectomized rats treated with progesterone plus oestrogen. These results show that ICAM1 up-regulation at the time of implantation is under the control of progesterone, and is not dependent on cytokine release from the blastocyst or in semen. FGG dimerization increased (P < 0.05) on day 6 of pregnancy compared with day 1, and was not up-regulated in day 6 pseudopregnant animals, suggesting this increase is dependent on a developing blastocyst. The presence of ICAM1 and FGG in the uterine epithelium at the time of implantation in the rat is similar to that seen in lymphocyte-endothelium adhesion, and we suggest a similar mechanism in embryo-uterine epithelium adhesion is utilized.

Relationships between innovative and traditional parameters to investigate semen quality in pigs

Semen quality assessment represents a fundamental step for obtaining successful artificial insemination (AI). In commercial settings, the semen employed for AI should be of high quality but traditional semen quality estimates are not sufficiently sensitive to discriminate between differences among samples in terms of fertilising ability. Therefore, more discriminative sperm characteristics need to be identified in order to better predict fertility outcome. In the present study, a series of molecular aspects of semen, represented by heat shock proteins, oxidative stress status, antioxidant potential and tumour necrosis factor (TNF)-alpha were evaluated and analysed. Several relationships between traditional and investigated molecular semen quality estimates were found by using a multivariate analysis approach. Tumour necrosis factor (TNF)-alpha was identified in boar seminal plasma resulting in positive correlations with several sperm quality aspects and particularly with motility. The protective roles of antioxidant molecules and heat shock proteins have been demonstrated confirming the data previously published in the literature.

Identification of sperm forward motility-related proteins in human seminal plasma

Seminal plasma, an amorphous material that exists in semen, contains proteins related to sperm forward motility. Employing affinity chromatography with ConA beads and protein ultrafiltration, we isolated and concentrated proteins from heated human seminal plasma. Results of computer-assisted semen analyses (CASA) demonstrated that the forward motility index of bovine spermatozoa from the epididymal caput, incubated with proteins and theophylline, was significantly different from that of spermatozoa incubated with theophylline alone (P < 0.01). The electrophoreses revealed that the protein bands with high molecular weights in the gel of PAGE changed into low molecular weights in the gel of SDS-PAGE. Furthermore, proteins from a separated portion of the PAGE gel were still able to stimulate spermatozoa from the epididymal caput to gain forward motility. Two-dimensional (2D)-gel electrophoresis and mass spectrometry indicated that spots focused on the portion seemed, according to their amino acid sequences, to be like human alpha-1-antitrypsin and zinc-alpha-2-glycoprotein (ZAG) precursors. Western blot analysis showed the presence of these two proteins in seminal plasma. These proteins, related to the forward motility of spermatozoa in human seminal plasma, may play important roles during maturation of spermatozoa, from the epididymis through fertilization in the female reproductive tract.