Seminal plasma zinc concentration and alpha-glucosidase activity with respect to semen quality

Zinc as a Modulator of Male Fertility: Interplay Between Lipid Metabolism, Oxidative Stress, and Sperm Function

Infertility is a multifaceted and pressing global health challenge, with male reproductive impairment playing a significant role in its overall burden. Zinc (Zn), a biologically indispensable trace element, is fundamental to spermatogenesis and overall male reproductive function. This narrative review explores the following aspects: (1) the mechanistic function of Zn in spermatogenesis, (2) the impact of oxidative stress on Zn status and male infertility, (3) the interplay between Zn and lipid metabolism in male reproductive physiology, (4) the relationship between Zn concentrations and semen parameters, and (5) the effects of Zn supplementation on sperm quality, alongside relevant institutional recommendations. The molecular pathways underlying Zn deficiency-induced enzymatic dysfunction, oxidative stress, and lipid homeostasis disruption remain partially elucidated, warranting further investigation into their interdependent effects on male infertility. While accumulating evidence suggests that Zn supplementation may have therapeutic potential in male infertility management, guidelines for its clinical application vary considerably across institutions and regions. To establish a clear and evidence-based framework for the function of Zn in male reproductive health, future research should prioritize determining of optimal Zn levels, the mechanistic links between Zn and lipid metabolism, and the long-term clinical outcomes of Zn supplementation in infertile populations.

Association Between Zinc Levels and the Impact of Its Deficiency on Idiopathic Male Infertility: An Up-to-Date Review

BACKGROUND

Zinc (Zn) is an essential metal that plays a critical role in normal testicular development, spermatogenesis, prevention of sperm degradation, and overall male fertility. This review aims to offer a comprehensive and current overview of seminal plasma Zn levels in fertile men worldwide. It also aims to compare Zn levels in seminal plasma and blood (serum/plasma) between infertile men (cases) and fertile men (controls), examine the impact of Zn on sperm quality and the reproductive hormone, and highlight the effects of Zn supplementation therapy in male infertility.

METHODS

To achieve these goals, peer-reviewed studies from 2000 to 2024 were interrogated with regard to strict inclusion/exclusion criteria and were then thoroughly reviewed and analyzed.

RESULTS

Our findings indicate that maintaining optimal seminal plasma Zn levels is crucial, as low Zn levels are linked to impaired spermatogenesis and male infertility, while high Zn levels can cause oxidative stress and other changes that contribute to infertility. Seminal plasma Zn levels from 100 to 200 mg/L among fertile men worldwide can be roughly considered safe. Comparative analysis showed that a greater number of studies reported lower levels of seminal Zn in cases than in controls. Research into the impact of Zn levels in seminal plasma has shown that, although the results are not yet conclusive, altered (non-normal) Zn levels could influence semen parameters-particularly motility, morphology, and sperm count-and the level of the reproductive hormone, testosterone. Zinc-deficient infertile men could benefit from supplement therapy.

CONCLUSIONS

Assessment of seminal plasma Zn levels in infertile men could provide valuable information and aid in diagnosis and treatment planning.

Association of seminal plasma zinc levels with human semen quality and its toxic effects on sperm motility

Infertility has become one of the most common chronic diseases among reproductive- aged individuals, and male factors account for about 50 %. Zinc is a trace element that is essential for sperm quality and male reproductive system. Although several current studies with small sample sizes have investigated this relationship, the conclusions have been still controversial. Here, using a large population sample involved 25,915 participants from Changzhou Maternity and Child Health Care Hospital, we revealed an inverted "U"-shaped trend between seminal plasma zinc concentrations and sperm motility PR/PR + NP (PR, progressive motility; NP, non-progressive motility). The results showed that the highest values of sperm PR/PR + NP observed in the group with intermediate concentrations of zinc (Group 2, 0.25-2.11 mmol/L). The mean values were 43.17 ± 19.03 % and 56.64 ± 20.28 %, respectively. And the lowest values came out in the highest zinc levels group (Group 4, > 3.04 mmol/L). In vitro cell experiments also showed that zinc caused dose-dependent cytotoxicity for GC-2 cells at a threshold value. Furthermore, RNA-seq analysis demonstrated that high concentrations of zinc exerted toxic effects on GC-2 cells through immune injury. Taken together, our findings suggested that moderate amounts of zinc are crucial for human reproduction and excessive concentrations may have adverse effects on male fertility.

Understanding seminal plasma in male infertility: emerging markers and their implications

Infertility affects a significant proportion of the reproductive-aged population, with male-associated factors contributing to over half of the cases. However, current diagnostic tools have limitations, leading to an underestimation of the true prevalence of male infertility. While traditional semen parameters provide some insights, they fail to determine the true fertility potential in a substantial number of instances. Therefore, it is crucial to investigate additional molecular targets responsible for male infertility to improve understanding and identification of such cases. Seminal plasma, the main carrier of molecules derived from male reproductive glands, plays a crucial role in reproduction. Amongst its multifarious functions, it regulates processes such as sperm capacitation, sperm protection and maturation, and even interaction with the egg's zona pellucida. Seminal plasma offers a non-invasive sample for urogenital diagnostics and has shown promise in identifying biomarkers associated with male reproductive disorders. This review aims to provide an updated and comprehensive overview of seminal plasma in the diagnosis of male infertility, exploring its composition, function, methods used for analysis, and the application of emerging markers. Apart from the application, the potential challenges of seminal plasma analysis such as standardisation, marker interpretation and confounding factors have also been addressed. Moreover, we have also explored future avenues for enhancing its utility and its role in improving diagnostic strategies. Through comprehensive exploration of seminal plasma's diagnostic potential, the present analysis seeks to advance the understanding of male infertility and its effective management.

Seminal biomarkers and their correlations to semen parameters in subfertile men

Research question

To assess the levels of seminal biomarkers fructose, zinc and citrate and their correlations to semen parameters in infertile men.

Design

200 infertile male participants undergoing fertility assessment at Singapore General Hospital (SGH), Singapore were recruited prospectively, from June 2020 to August 2021. Their semen samples were assessed for seminal parameters, biomarker levels of fructose, citrate and zinc, leukocyte concentrations and aerobic cultures. They were also assessed for their smoking habits.

Results

Sperm concentrations were negatively correlated to seminal fructose levels, r = -0.262, P < 0.001. Progressive motility were positively correlated to seminal citrate levels, r = 0.181, P = 0.014. Sperm morphology and total motile sperm count (TMSC) were positively correlated to seminal zinc and citrate levels, P < 0.05. Zinc and citrate levels were significantly reduced in teratozoospermia, asthenoteratozoospermia and oligoasthenoteratozoospermia groups compared to normozoospermia, P < 0.05. The presence of infection was associated with elevated leukocyte concentrations, lower sperm concentration (12.5 vs 55.8 million/mL, P = 0.024) and fructose levels (35.5 vs 49.2 µmol/ejaculate). Heavy smokers compared to light smokers, had lower sperm concentrations (35.3 vs 49.4 million/mL), TMSC (30.9 vs 47.5 million) and zinc levels (4.9 vs 6.7 µmol/ejaculate) and significantly lower citrate levels (52.6 vs 79.2 µmol/ejaculate, P = 0.029).

Conclusions

Higher zinc and citrate levels correlated with better progressive motility, sperm morphology and TMSC. Smoking negatively impacted zinc and citrate levels, thereby affecting sperm quality. In conclusion, the inclusion of biomarkers in basic male work-up assessment would assist in identifying common deficiencies and aid in adequate replacement therapy.

Correlation of zinc level in spermoplasm with fertility characteristics of human ejaculate

Background: Zinc is essential for the normal functioning of the male reproductive system. The data on the diagnostic value of the determination of zinc in human spermoplasm and the relationship of its level with the main parameters of sperm fertility are contradictory. Aims: Study of correlations of zinc level in spermoplasm with spermogram characteristics. Methods: Sperm of men of reproductive age (n=486, average age 33.073.03 years) was studied. In addition to the standard spermogram, MAR tests (IgA, IgG and IgM) were performed in the sperm samples, the degree of fragmentation of sperm DNA was assessed, the interaction of sperm with hyaluronic acid was assessed, acrosine activity, neutral alpha-glucosidase activity was determined, citric acid, fructose and glycodelin levels were determined, the level of reactive oxygen species was studied. Determination of the zinc level in the spermoplasm was carried out by a standard spectrophotometric method with 5-Br-PAPS chromogen. Pearson's formula was used for correlation analysis. The study was conducted from 2018 to May 2022, once. Results: A significant negative correlation of the zinc level in the spermoplasm with the age of men was revealed (r=-0.1625, p0.001). The level of zinc in the spermoplasm was weakly negatively correlated with the dilution time and with the viscosity of the sperm. The positive correlation was with the number of spermatozoa (r=0.1345, p0.01) and their mobility (r=0.3825, p0.00001). The level of zinc in the spermoplasm negatively correlates with the degree of fragmentation of sperm DNA and with the amount of reactive oxygen species, and with the test for binding of sperm with hyaluronic acid positively. Conclusions: The level of zinc in the spermoplasm significantly correlates with a number of physiological and biochemical characteristics of sperm. The data obtained allow us to recommend the determination of zinc in the sperm plasma not only to assess the functional activity of the prostate gland, but also to diagnose the fertility of the ejaculate, as well as to optimize therapy with zinc-containing drugs and improve control over the effectiveness of the treatment.

Evaluating the Serum and Seminal Plasma Levels of Zinc and Cadmium in Smokers and Their Relation to the Semen Parameters

Cigarette smoking appears to have adverse effects of male reproductivity. The interplay between zinc and cadmium presumably plays a role in mediating toxic effects of smoking. This work was conducted to study serum and seminal plasma zinc and cadmium level in smokers compared to non-smokers. Seventy males were included: 35 smokers (group I) (smoking ˃20 cigarettes/day with mild smoking index <400) and 35 age-matched non-smokers (group II). Semen analysis was performed according to the WHO laboratory manual 2010. Atomic absorption spectrophotometer was used to detect zinc and cadmium amounts in both blood plasma and semen of any groups. Smoker group showed significantly lower sperm density, motility (P=0.001), and sperm viability (P=0.002) and higher abnormally formed sperms. Seminal zinc level was significantly lower in smokers (P=0.038).There was significant negative correlation between seminal zinc and smoking index and significant positive correlation between seminal zinc levels and sperm motility (P=0.008) and viability percentage (P=0.001). Seminal cadmium level was significantly higher in smoker (P=0.022). Significant positive correlation between seminal cadmium and both age and smoking index (P=0.003) and significant negative correlation between seminal cadmium and sperm density (P=0.005), motility (P=0.047), and viability (P=0.039). Seminal zinc level was negatively correlated to seminal cadmium level (P=0.020). Smoking has deleterious effects on semen quality hence fertility through several toxicants and chemicals. Reduced zinc levels and elevated cadmium levels were evident in smokers which have significant role in the adverse effects on the semen parameters.

The Influence of Zinc and Heavy Metals in Feed and Water on the Quality of Cryopreserved Bull Semen

This study aimed to assess the influence of different concentrations of zinc (Zn), lead (Pb), mercury (Hg) and cadmium (Cd) found in the feed and water provided to bulls on the concentrations of these metals in cryopreserved bull semen, and to determine their influence onto semen quality parameters. Correlations between heavy metal concentrations in the semen and the quality parameters of semen as estimated by computer-assisted sperm analysis (CASA) and flow cytometry (FC) methods were determined.

A total of 40 cryopreserved semen samples originating from bulls housed in 4 different centers for artificial insemination (A, B, C and D) were examined, making a total of 160 samples. The concentrations of metals and semen quality parameters were determined in cryopreserved semen of 10 bulls from each center, namely 4 samples from each bull. Concentrations of Zn, Pb, Hg and Cd in hay and concentrated feed were within the allowed limits as proposed by the National Research Council (NRC, 2000). A strong negative correlation was detected between curvilinear velocity (VCL) and Zn concentrations in the semen (P < 0.01; r = -0.772) in group D, and a positive correlation of VCL with Pb concentrations (P < 0.05 and r = 0.718) in group B. Mercury concentrations in cryopreserved semen correlated negatively to the percent of live sperm cells with intact acrosomes (V/IA: P < 0.05; r = -0.640) and positively with the percent of dead sperm cells with damaged acrosomes (D/DA: P < 0.01; r = 0.766) in group D. This finding confirms the hypothesis that Hg, even at low concentrations, may cause acrosome damage.

Progesterone and anandamide diminish the inhibitory effect of zinc on mature human sperm

Zinc ion (Zn2+) homeostasis is very important for sperm capacitation and hyperactivation. Zn2+ is a specific inhibitor of the voltage-dependent proton channel (Hv1). Intracellular alkalisation of human spermatozoa is mainly dependent on opening of Hv1. Anandamide may affect spermatozoa through activation of Hv1. An increase in intracellular pH and progesterone (P4) activate cation channels of spermatozoa (CatSper). This study was designed to elucidate the interaction between ZnCl2, P4 and anandamide on human sperm function and intracellular calcium concentrations ([Ca2+]i). Human normal semen samples (n = 30) were diluted (20 × 106 spermatozoa mL-1) and divided into control and ethanol (0.01%)-, anandamide (1 nM)-, ZnCl2 (1 mM)-, P4 (10µM)-, anandamide+ZnCl2- and P4+ZnCl2-treated groups. Sperm kinematics, viability, acrosome status and [Ca2+]i were assessed. The percentage of viable and motile spermatozoa and sperm velocity was reduced in the ZnCl2-treated groups. Anandamide and P4 attenuated the inhibitory effects of ZnCl2 on sperm kinematics. Loss of the acrosome membrane was observed in all experimental groups. P4 and anandamide are present naturally in secretions of the female reproductive tract and modulate the inhibitory effects of ZnCl2 on sperm kinematics. This attenuation is probably due to a change in [Ca2+]i and prevention of Hv1 inactivation by P4 and anandamide respectively.

In Vivo and In Vitro Evaluation of Bull Semen Processed with Zinc (Zn) Nanoparticles

Defective sperms cause fertilization failure under both in vivo and in vitro conditions. Therefore, providing optimal conditions during semen storage is a prerequisite for maintaining viability. The current study investigated bull semen quality in vitro and in vivo when zinc (Zn) nanoparticles were used as antioxidant during semen processing and cryopreservation. In total, 32 ejaculates were collected from four Holstein bulls. All ejaculates were pooled and diluted with Bioxcell-extender containing 0 (control group), 10^-6, 10^-5, 10^-4, 10^-3, and 10^-2 M of Zn nanoparticles. Several physical and biochemical sperm parameters were determined after freeze-thawing process. In vitro embryo development rate and pregnancy rate were monitored after in vitro fertilization or artificial insemination using semen treated with Zn nanoparticles. Plasma membrane integrity was improved (P < 0.05) in bull semen treated with 10^-6 M (69.3%), and 10^-2 (62.4%) of Zn nanoparticles compared to untreated group (51.3%). In addition, proportions of live spermatozoa with active mitochondria were increased (P < 0.05) in semen supplemented with Zn nanoparticles at concentration of 10^-6 M (67.3%), and 10^-2 (85.3%) compared to control group (49.8%). Moreover, the level of MDA was lower (P < 0.05) in semen with Zn nanoparticles at 10^-6 M (2.97 mol/mL) and 10^-2 (2.7 mol/mL) concentrations than control semen samples (3.77 mol/mL). However, sperm total and progressive motility, sperm viability, DNA fragmentation, and pregnancy rate were not affected by treatment of semen with Zn nanoparticles. On the other hand, supplementation of in vitro maturation media with 10^-6 M Zn nanoparticles has increased blastocyst rate (P < 0.05) compared to other experimental groups, while addition of Zn nanoparticles-treated sperm during in vitro fertilization did not affect embryo development rate. In conclusion, supplementation of Zn nanoparticles to semen has improved its quality without affecting embryo development rate in vitro. However, in vitro embryo development rate was increased when Zn nanoparticles were supplemented to IVM media. This support the notion of Zn nanoparticles beneficial action on improving bovine gametes quality without affecting pregnancy rate.

The Role of Zinc in Male Fertility

Several studies proposed the importance of zinc ion in male fertility. Here, we describe the properties, roles and cellular mechanisms of action of Zn²⁺ in spermatozoa, focusing on its involvement in sperm motility, capacitation and acrosomal exocytosis, three functions that are crucial for successful fertilization. The impact of zinc supplementation on assisted fertilization techniques is also described. The impact of zinc on sperm motility has been investigated in many vertebrate and invertebrate species. It has been reported that Zn²⁺ in human seminal plasma decreases sperm motility and that Zn²⁺ removal enhances motility. Reduction in the intracellular concentration of Zn²⁺ during epididymal transit allows the development of progressive motility and the subsequent hyper activated motility during sperm capacitation. Extracellular Zn²⁺ affects intracellular signaling pathways through its interaction with the Zn²⁺ sensing receptor (ZnR), also named GPR39. This receptor was found in the sperm tail and the acrosome, suggesting the possible involvement of Zn²⁺ in sperm motility and acrosomal exocytosis. Our studies showed that Zn²⁺ stimulates bovine sperm acrosomal exocytosis, as well as human sperm hyper-activated motility, were both mediated by GPR39. Zn²⁺ binds and activates GPR39, which activates the trans-membrane-adenylyl-cyclase (tmAC) to catalyze cAMP production. The NHE (Na⁺/H⁺-exchanger) is activated by cAMP, leading in increased pHi and activation of the sperm-specific Ca²⁺ channel CatSper, resulting in an increase in [Ca²⁺]_i, which, together with HCO₃⁻, activates the soluble adenylyl-cyclase (sAC). The increase in [cAMP]_i activates protein kinase A (PKA), followed by activation of the Src-epidermal growth factor receptor-Pphospholipase C (Src-EGFR-PLC) cascade, resulting in inositol-triphosphate (IP₃) production, which mobilizes Ca²⁺ from the acrosome, causing a further increase in [Ca²⁺]_i and the development of hyper-activated motility. PKA also activates phospholipase D1 (PLD1), leading to F-actin formation during capacitation. Prior to the acrosomal exocytosis, PLC induces phosphadidylinositol-4,5-bisphosphate (PIP₂) hydrolysis, leading to the release of the actin-severing protein gelsolin to the cytosol, which is activated by Ca²⁺, resulting in F-actin breakdown and the occurrence of acrosomal exocytosis.

Zinc supplementation within the reference ranges for zinc status in cattle improves sperm quality without modifying in vitro fertilization performance

Zinc (Zn) has important functions in mammalian reproductive processes. In cattle, Zn status can be classified as deficient, marginal, and adequate, depending on the plasma Zn concentration. In addition, Zn deficiency can lead to reproductive failure. The aim of this study was to investigate the effect of maternal Zn status at the beginning of a fixed-time artificial insemination (FTAI) treatment regimen on pregnancy rate in cattle, and evaluate the effect of supplementing in vitro fertilization (IVF) medium with Zn concentrations within the reference range for Zn status on sperm quality and IVF performance. Pregnancy rates of animals with marginal and adequate Zn status did not differ, and there were no Zn-deficient animals detected. Supplementation of 0.8 μg/mL Zn to IVF medium enhanced progressive motility, sperm viability, functional sperm membrane integrity (HOST), acrosomal integrity and sperm-zona binding, without modifying pronuclear formation, or development of embryos to the cleavage or blastocyst stage after IVF. In conclusion, the present results indicate pregnancy rates are not associated with maternal Zn status at the beginning of the FTAI treatment regimen if Zn status is marginal or adequate. Furthermore, supplementation of IVF medium with Zn at concentrations which is considered adequate for Zn status in cattle led to improved sperm quality, without having effects on embryo development in cattle.

The effect of zinc oxide on rooster semen cryopreservation

1. Deleterious effects from the freeze-thawing process on post-thawed sperm quality attributes are main limiting factors in cryopreservation. The current study was conducted to determine the effect of semen extender containing zinc oxide (ZnO) on post-thaw rooster sperm quality indices.2. Semen samples from six, 60-week-old broiler breeder roosters were collected weekly during five successive weeks. The samples were mixed and divided into three equal parts and diluted with semen extender containing different levels of ZnO; 0 (ZnO-0), 1 (ZnO-1) or 2 (ZnO-2) µg/ml. After thawing, motility and velocity parameters, plasma membrane functionality, apoptotic like changes, mitochondrial membrane potential (MMP), and DNA fragmentation index (DFI) were evaluated.3. Results showed that the addition of ZnO in the extender quadratically affected (P < 0.01) total motility (TM), progressive motility (PM), and average path velocity (VAP) with the highest values were noted in the ZnO-1 group. Levels of ZnO quadratically affected percentages of live (P < 0.01), apoptotic (P < 0.03) and dead (P < 0.10) spermatozoa, where the highest percentage of live, and the lowest percentage of apoptotic or dead spermatozoa was for the ZnO-1 group. Although adding ZnO quadratically affected plasma membrane functionality and MMP (P < 0.01), it did not affect (P > 0.05) DFI.4. In conclusion, there were some beneficial effects of ZnO supplementation in semen extender on post-thawed rooster sperm quality which may result in a better freezability.

Effects of TLR4 overexpression on sperm quality, seminal plasma biomarkers, sperm DNA methylation and pregnancy rate in sheep

Genetic modification provides a means to enhancing disease resistance in animals. In this study, the first generation of genetically modified (GM) sheep overexpressing TLR4 was produced by microinjection for better disease resistance. To compare semen characteristics including sperm quality, seminal plasma biochemical index, sperm DNA methylation and pregnancy rate of three-year old transgenic sheep with TLR4 overexpressed (toll like receptor 4, TLR4) and non-transgenic ram. Sixteen transgenic ram of F0 generation were produced by microinjection of the TLR4 plasmid into the pronucleus of fertilized ova. Seven transgenic sheep of F1 generation was produced by breeding F0 transgenic founders with non-transgenic sheep of the same breed. There were no significant differences between transgenic and control rams for all semen quality parameters, including semen volume, sperm concentration, sperm viability, and percentages of sperm with an intact plasma membrane, acrosomal integrity, and viable sperm with high mitochondrial membrane potential in both F0 and F1 generation. Furthermore, no significant differences were found for seminal plasma concentrations of zinc, neutral alpha-glucosidase, acid phosphatase or fructose, nor for levels of H19 and IGF2R methylation in sperm DNA. In addition, pregnancy rate was also similar between these two groups. In conclusion, there was no evidence that TLR4 overexpression altered the sperm quality, seminal plasma or sperm DNA of transgenic sheep.

Zinc: A Necessary Ion for Mammalian Sperm Fertilization Competency

The importance of zinc for male fertility only emerged recently, being propelled in part by consumer interest in nutritional supplements containing ionic trace minerals. Here, we review the properties, biological roles and cellular mechanisms that are relevant to zinc function in the male reproductive system, survey available peer-reviewed data on nutritional zinc supplementation for fertility improvement in livestock animals and infertility therapy in men, and discuss the recently discovered signaling pathways involving zinc in sperm maturation and fertilization. Emphasis is on the zinc-interacting sperm proteome and its involvement in the regulation of sperm structure and function, from spermatogenesis and epididymal sperm maturation to sperm interactions with the female reproductive tract, capacitation, fertilization, and embryo development. Merits of dietary zinc supplementation and zinc inclusion into semen processing media are considered with livestock artificial insemination (AI) and human assisted reproductive therapy (ART) in mind. Collectively, the currently available data underline the importance of zinc ions for male fertility, which could be harnessed to improve human reproductive health and reproductive efficiency in agriculturally important livestock species. Further research will advance the field of sperm and fertilization biology, provide new research tools, and ultimately optimize semen processing procedures for human infertility therapy and livestock AI.

Elevated seminal plasma estradiol and epigenetic inactivation of ESR1 and ESR2 is associated with CP/CPPS

Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) is associated with urinary tract symptoms and hormonal imbalances amongst others. The heterogeneous clinical presentation, unexplored molecular background and lack of prostate biopsies complicate therapy. Here, using liquid biopsies, we performed a comprehensive translational study on men diagnosed with CP/CPPS type III (n= 50; median age 39.8, range 23-65) and age-matched controls (n= 61; median age 36.8, range 20-69), considering biochemical parameters of blood and ejaculates, and epigenetic regulation of the estrogen receptor genes (ESR1 and ESR2) in leukocytes isolated from blood (systemic regulation) and in somatic cells isolated from ejaculates (local regulation). We found elevated 17β-estradiol (E2) levels in seminal plasma, but not in blood plasma, that was significantly associated with CP/CPPS and impaired urinary tract symptoms. In ejaculated somatic cells of CP/CPPS patients we found that ESR1 and ESR2 were both significantly higher methylated in CpG-promoters and expressionally down-regulated in comparison to controls. Mast cells are reported to contribute to CP/CPPS and are estrogen responsive. Consistent with this, we found that E2 -treatment of human mast cell lines (HMC-1 and LAD2) resulted in altered cytokine and chemokine expression. Interestingly, in HMC-1 cells, possessing epigenetically inactivated ESR1 and ESR2, E2 -treatment led to a reduced transcription of a number of inflammatory genes. Overall, these data suggest that elevated local E2 levels associate with an epigenetic down-regulation of the estrogen receptors and have a prominent role in CP/CPPS. Investigating E2 levels in semen could therefore serve as a promising biomarker to select patients for estrogen targeted therapy.

Impact of cigarette-smoking on sperm DNA methylation and its effect on sperm parameters

DNA methylation is an epigenetic modification of the genome. The purpose of this study was to determine the influence of cigarette-smoking on sperm DNA methylation from a genomewide survey of sperm samples and to ascertain its effect on sperm parameters. Twenty-eight sperm DNA samples (from 14 fertile smokers as a case study and 14 proven fertile nonsmokers as controls) were subjected to Infinium 450K BeadChip arrays to identify the changes in the DNA methylation level between the two groups. Then, deep bisulphite sequencing was used to validate five CpGs on 78 samples. The results from the Infinium 450K found that only 11 CpGs showed a significant difference in DNA methylation between the case and the control groups. Five CpGs of the eleven (cg00648582, cg0932376, cg19169023, cg23841288 and cg27391564) underwent deep bisulphite sequencing where cg00648582, related to the PGAM5 gene, and the cg23841288 CpGs, related to the PTPRN2 gene amplicons, showed a significant increase in their DNA methylation level in more than one CpG in the case group. In contrast, a significant decrease was found at cg19169023 and at its various neighbouring CpGs in the TYRO3 gene-related amplicons. Furthermore, this study demonstrated a significant correlation between the variation in sperm DNA methylation level and standard sperm parameters in the case group.

Zinc Levels in Seminal Fluid in Infertile Males and its Relation with Serum Free Testosterone

INTRODUCTION

The role of zinc is critical to reproduction potential. Seminal zinc is thought to be derived almost exclusively from prostatic secretions. Sperm motility is significantly influenced by zinc. Zinc deficiency has been linked with male sterility and subfertility.

AIM

To assess the influence of seminal plasma zinc on seminogram characteristics and whether endogenous testosterone affects the seminal levels of zinc.

MATERIALS AND METHODS

The semen samples were obtained from 150 male partners of infertile couples who attended the Reproductive Biology Unit of the Department of Physiology, within the age 21-50 years and semen samples were analysed for the routine seminogram parameters. All the subjects were classified into two main groups, A- the subjects with normal ejaculates (n=62) and B- the subjects with abnormal ejaculates, who were further sub divided into the following groups: i) Asthenoteratozoospermics (n=43); ii) Oligoasthenoteratozoospermics (n=24); and iii) Azoospermics (n=21). The seminal plasma zinc was measured spectrophotometrically. The sample for serum free testosterone was sent to Thyrocare laboratory.

RESULTS

The seminal plasma zinc was found to be significantly lower in the abnormal ejaculates than in the normal ejaculates. A statistically significant positive correlation was observed between the seminal plasma zinc and serum free testosterone (p<0.05, r=0.449). Statistically significant correlation was also found between seminal plasma zinc and all the seminogram parameters such as the sperm concentration, sperm motility and sperm morphology (p<0.05, r= 0.86, 0.87 and 0.86 respectively).

CONCLUSION

Low seminal plasma zinc might be a significant causative factor in impairing sperm functions and its dependence on endogenous free testosterone, is observed from a positive correlation between the two.

Zinc: The Metal of Life

The importance of zinc was 1st reported for Aspergillus niger. It took over 75 y to realize that zinc is also an essential trace element for rats, and an additional 30 y went by before it was recognized that this was also true for humans. The adult body contains about 2 to 3 g of zinc. Zinc is found in organs, tissues, bones, fluids, and cells. It is essential for many physiological functions and plays a significant role in a number of enzyme actions in the living systems. Bioinformatics estimates report that 10% of the human proteome contains zinc-binding sites. Based on its role in such a plethora of cellular components, zinc has diverse biological functions from enzymatic catalysis to playing a crucial role in cellular neuronal systems. Thus, based on the various published studies and reports, it is pertinent to state that zinc is one of the most important essential trace metals in human nutrition and lifestyle. Its deficiency may severely affect the homeostasis of a biological system. This review compiles the role of zinc in prophylaxis/therapeutics and provides current information about its effect on living beings.

The role of oxidative stress and antioxidants in male fertility

Oxidative stress results from the imbalance between production of the reactive oxygen species (ROS) and the protective effect of the antioxidant system responsible for their neutralization and removal. An excess of ROS causes a pathological reaction resulting in damage to cells and tissues. Spermatozoa are particularly vulnerable to the harmful effects of ROS. Oxidative stress affects their activity, damages DNA structure, and accelerates apoptosis, all of which consequently decrease their numbers, hinders motility and development of normal morphology, and impairs function. This leads to disturbances in fertility or embryo development disorder. The main cellular source of ROS in the semen are immature sperm cells and white blood cells. The increase in the number of leukocytes may be due to infection and inflammation, but can also be secondary to harmful environmental factors, long sexual abstinence, or varicocele. The protective antioxidant system in the semen is composed of enzymes, as well as nonenzymatic substances, which closely interact with each other to ensure optimal protection against ROS. Non–enzymatic antioxidants include vitamins A, E, C, and B complex, glutathione, pantothenic acid, coenzyme Q10 and carnitine, and micronutrients such as zinc, selenium, and copper. It seems that a deficiency of any of them can cause a decrease in total antioxidant status. In vitro and in vivo that studies demonstrate many antioxidants possess a beneficial effect on fertility and, therefore, their use is recommended as supportive therapy for the treatment of infertility in men.

Oral zinc supplementation restores high molecular weight seminal zinc binding protein to normal value in Iraqi infertile men

Background

Zinc in human seminal plasma is divided into three types of ligands which are high (HMW), intermediate (IMW), and low molecular weight ligands (LMW). The present study was aimed to study the effect of Zn supplementation on the quantitative and qualitative characteristics of semen along with Zinc Binding Protein levels in the seminal plasma in asthenozoospermic patients.

Methods

Semen samples were obtained from 37 fertile and 37 asthenozoospermic infertile men with matched age. The subfertile group was treated with zinc sulfate, every participant took two capsules per day for three months (each one 220mg). Semen samples were obtained (before and after zinc sulfate supplementation). After liquefaction seminal fluid at room temperature, routine semen analyses were performed. For determination of the amount of zinc binding proteins, the gel filtration of seminal plasma on Sephadex G-75 was performed. All the fractions were investigated for protein and for zinc concentration by atomic absorption spectrophotometry. Evaluation of chromatograms was made directly from the zinc concentration in each fraction.

Results

A significant high molecular weight zinc binding ligands percentage (HMW-Zn %) was observed in seminal plasma of fertile males compared with subfertile males. However, seminal low molecular weight ligands (LMW-Zn) have opposite behavior. The mean value of semen volume, progressive sperm motility percentage and total normal sperm count were increased after zinc sulfate supplementation.

Conclusions

Zinc supplementation restores HMW-Zn% in seminal plasma of asthenozoospermic subjects to normal value. Zinc supplementation elevates LMW-Zn% in seminal plasma of asthenozoospermic subjects to more than normal value.

Trial registration

ClinicalTrials.gov identifier NCT01612403

Seminal plasma metals concentration with respect to semen quality

The aim of the current study was to assess relationships between multiple metals burden in human seminal plasma and semen quality parameters. Levels of five metals (lead, manganese, copper, arsenic, and selenium) in human seminal plasma were determined by inductively coupled plasma mass spectrometry (ICP-MS), and the correlations between the metal concentrations and semen parameters (sperm concentration, sperm motility rate, and sperm morphology) were analyzed. The activities of acid phosphatase (ACP) and of α-glucosidase in human seminal plasma were also determined. Of the 100 subjects, 21 had fertility problems according to the World Health Organization criteria and were designated as "abnormal group." Significant inverse correlations were found between the concentrations of Cu, As, Pb, and the sperm concentrations (r (Cu) = -0.312, P (Cu) = 0.029; r (As) = -0.328, P (As) = 0.021; r (Pb) = -0.377, P (Pb) = 0.008). Moreover, the Cu, Mn, and Se concentrations were significantly higher in the abnormal group than that in the normal group (P (Cu) = 0.024, P (Mn) = 0.002, P (Se) = 0.002). The ACP activity was significantly higher in the normal group than that in the abnormal group (P = 0.021). We also found a significantly negative correlation between α-glucosidase activity and the levels of As (r = -0.367, P = 0.023). These findings provide evidence for relationships between human semen quality and metal exposures. These relationships are consistent with animal data, but additional human and mechanistic studies are needed.

Could zinc prevent reproductive alterations caused by cigarette smoke in male rats?

The aim of the present study was to evaluate the effects of zinc on fertility through semen parameters, testosterone level and oxidative DNA damage to spermatozoa of rats exposed to cigarette smoke. Male Wistar rats (60 days old) were divided into four groups (n = 10 per group): control, cigarette-smoking (20 cigarettes per day), zinc (zinc chloride 20 mg kg–1 day–1) and zinc plus cigarette-smoking (zinc chloride 20 mg kg–1 day–1; 20 cigarettes per day). The treatment was applied for nine weeks and the following parameters were analysed: bodyweight, wet weights of the reproductive organs and the adrenal gland, plasma testosterone concentration, testicular function (seminal analysis and daily sperm production) and sperm DNA oxidative damage. The exposure to cigarette smoke decreased testosterone concentration, the percentage of normal morphology and the motility of spermatozoa. In addition, this exposure increased sperm DNA oxidative damage. Zinc treatment protected against the toxic damage that smoking caused to spermatozoa. This study showed a correlation between smoking and possible male infertility and subfertility, and also that the majority of smoking-induced changes in spermatozoa were prevented by zinc treatment. In conclusion, zinc, an antioxidant and stimulant of cell division, can be indicated as a promising treatment in men with infertility caused by the toxic components of cigarette smoke.

Altered antioxidant status and increased lipid per-oxidation in seminal plasma of tunisian infertile men

Human seminal plasma is a natural reservoir of antioxidants that protect spermatozoa from oxidative damages. There is evidence in literature supports the fact that impairments in seminal antioxidant and lipid per-oxidation status play important roles in the physiopathology of male infertility. Our present study forms the first one which was carried out in Tunisia. We evaluated the antioxidant status in the seminal plasma of 120 infertile men programmed to In Vitro Fertilization (IVF) for the first tentative. Patients were characterized by an idiopathic infertility. They were divided into three groups: normozoospermics who were considered as controls (n=40), asthenozoospermics (Astheno; n=45) and oligoasthenoteratozoospermics (OAT; n=35). Seminal activities of superoxide dismutase (SOD) and glutathione peroxidase (GPX) and the levels of glutathione (GSH), zinc (Zn) and malondialdehyde (MDA) were measured. With the significant increase of the seminal activities of SOD and GPX in normozoospermics group, there were positive correlations observed between this enzymes and sperm quality. Also, significant elevated rates of seminal zinc and GSH were observed in control group, but there was contradictory associations reflecting the effects of these antioxidants on semen parameters. However, we noted significant increase of MDA levels in groups with abnormal seminogram. We showed negative associations between this per-oxidative marker and sperm parameters. These results obviously suggested that impairment on seminal antioxidants is an important risk factor for low sperm quality associated to idiopathic infertility and as a result can lead to poor IVF outcome.

Selenium, copper and zinc in seminal plasma of men with varicocele, relationship with seminal parameters

Varicocele has been associated with decrease in seminal parameters. Selenium (Se), copper (Cu), and zinc (Zn) are trace elements essential for normal spermatogenesis of mammals and play a critical role as antioxidant defense system enzymes. Se, Cu, and Zn are associated with sperm quality in fertile and infertile men. However, there is little information about Se, Cu, and Zn concentrations in semen in patients with varicocele and its association with seminal parameters. The purpose of this study was to determine the concentrations of Se, Cu, and Zn in semen of patients with varicocele and the relationship with seminal parameters. Total Reflection X-Ray Fluorescence was used for the fist time in the seminal fluid analysis. The concentration of selenium in men with varicocele was smaller than the normozoospermic group, while no differences were observed for both concentrations of zinc and copper. A significant positive correlation between zinc and selenium concentration was observed. Selenium in seminal plasma correlates with a good spermatozoa concentrations, motility, and morphology. Additionally, a significant positive correlation was observed between zinc levels and sperm count. In conclusion, a decrease in selenium concentration was associated with detriment of seminal parameters. A study should be conducted to evaluate the benefits of both zinc and selenium supplementation to improve seminal parameters in patients with varicocele.

Seminal Plasma Zinc Level May be Associated with the Effect of Cigarette Smoking on Sperm Parameters

The aim of this study was to investigate the effect of cigarette smoking on seminal plasma zinc levels and sperm parameters, and to examine the role of seminal plasma zinc. Semen samples from 79 non-smokers and 68 smokers were obtained. There was a significant decrease in seminal plasma zinc in smokers and a clear correlation between seminal plasma zinc levels and the extent of smoking. Sperm parameters (concentration, motility and morphology) among smokers were significantly lower in comparison to non-smokers. These parameters were also significantly decreased among smokers with abnormal zinc levels, while there was no significant difference between non-smokers with normal zinc and non-smokers with abnormal zinc levels. As previous studies have shown that seminal plasma zinc is associated with a decrease of anti-oxidant defences, seminal plasma zinc could be a contributor to the effects of cigarette smoking on sperm parameters. In conclusion, cigarette smoking can affect sperm parameters and this study may help towards providing a mechanistic explanation.

Zinc levels in seminal plasma are associated with sperm quality in fertile and infertile men

Zinc has antioxidative properties and plays an important role in scavenging reactive oxygen species. We hypothesized that in the absence of Zn, the possibility of increased oxidative damage exists that would contribute to poor sperm quality. Therefore, measurement of seminal Zn in the seminal plasma of males with a history of subfertility or idiopathic infertility is necessary and can be helpful in fertility assessment. The primary objective of the present study was to assess the relationship between Zn levels in seminal plasma with sperm quality in fertile and infertile men. Semen samples were provided by fertile (smoker [n = 17], nonsmoker [n = 19]) and infertile men (smoker [n = 15], nonsmoker [n = 21]). After semen analysis, concentrations of Zn, Mg, Ca, Na, and K in the seminal plasma of all groups were determined by atomic absorption spectroscopy. Element concentrations in seminal plasma of all groups were in the order Na > K > Ca > Zn > Mg. Fertile subjects, smoker or not, demonstrated significantly higher seminal Zn levels than any infertile group (P < .001). A trend was observed for a lower Zn levels in seminal plasma of smokers compared with nonsmokers. Seminal Zn in fertile and infertile (smokers or nonsmokers) males correlated significantly with sperm count (P < .01) and normal morphology of sperm (P < .001). There was a significantly positive correlation between seminal Zn with Ca (P < .01) and K (P < .01) levels in all specimens. In conclusion, poor Zn nutrition may be an important risk factor for low quality of sperm and idiopathic male infertility.

Are serum zinc and copper levels related to semen quality?

Low serum zinc levels are harmful to semen quality in Chinese men. In this study, eligible men aged 20-59 years old-excluding those who had ever had urinary or genital disease, tuberculosis, or occupational heavy metal contact-were examined for semen quality and serum zinc and copper concentrations. Progressive motility showed differences among the five copper groups, but multiple logistic analyses did not show that higher or lower serum copper levels had a significant effect on sperm quality. When serum zinc concentration was low, the risk of asthenozoospermia was higher. The ratio of Cu/Zn was higher in the progressive motility abnormal group than in the normal group.

Potential factors affecting semen quality in the Asian elephant (Elephas maximus)

BACKGROUND

One of the major obstacles in using artificial insemination to manage genetics of elephant population in captivity is the large variations in semen quality among ejaculates within the same and among individuals. The objectives of this study were to determine the influences of (1) age (2) seasonality (3) and circulating testosterone (SrTest), triiodothyronine (SrT3) and tetraiodothyronine (SrT4), as well as seminal (4) testosterone (SpTest), zinc (SpZn) and protein (SpTP) on semen quality in the Asian elephant

METHODS

Analyses, including motility, viability and morphology were performed in semen samples collected twice monthly from 13 elephant bulls (age range, 10-to 72-years) by manual stimulation between July 2004 and June 2005. Serum samples obtained monthly were assessed for SrTest, SrT3, SrT4, and seminal plasma samples were evaluated for, SpTest, SpZn and SpTP.

RESULTS

The highest semen quality was observed at age 23 to 43 years. Percentages of progressive motility and viable sperm were lowest at age 51 to 70 years (P < 0.05); on the other hand, sperm concentration was lowest at age 10 to 19 years (P < 0.05). Percentage of sperm with normal morphology was highest at age 23 to 43 years. The levels of SrT3, SrTest, SpTest and SpZn were lowest at age 51 to 70 years, whereas SrT4 was lowest at age 23 to 43 years. Seasonality significantly affected semen characteristics in which percentage of viable sperm and cell concentration were highest during rainy season and lowest during summer months (P < 0.05). However, percentage of sperm with normal morphology was highest in summer and lowest in rainy season (P < 0.05). Seasonality significantly influenced SrTest with elevated concentrations observed in rainy season and winter (P < 0.05).

CONCLUSION

This study indicates that age and seasonality had influence on semen characteristics in the Asian elephant. The knowledge obtained in this study will improve our understanding of the reproductive biology of this species.