Comparison of sperm viability with seminal plasma metal levels

Associations between seminal plasma metals/metalloids and semen quality: A cross-sectional study

Exposure to metals/metalloids is reported to potentially influence semen quality. While most studies have focused on single metal impacts, the link between exposure to multiple metals and semen quality has remained less explored. The study aimed to investigate the effects of both individual and mixed metal/metalloid exposure on semen quality. A total of 330 men were recruited from three reproductive centers in eastern China. Seminal plasma levels of 25 metals/metalloids and sperm parameters were determined. We used the Generalized Linear Model (GLM) and Restricted Cubic Spline (RCS) to assess the relationships between single metals/metalloids and semen quality. The weighted quantile sum (WQS) models were then applied to evaluate the combined effect of all these metals/metalloids. We observed positive associations of exposure to lithium (Li), zinc (Zn), and magnesium (Mg) with an increased risk of below reference values for progressive motility and total motility using a logistic regression model (P < 0.05). Additionally, our results also revealed a significant inverse relationship between aluminum (Al) and both sperm concentration and count, while cobalt (Co) demonstrated a positive association with sperm concentration (P < 0.05). Notably, the WQS model indicated a significant positive association between exposure to metal/metalloid mixtures and the risk of abnormal progressive motility (OR: 1.57; 95%CI: 1.10, 2.24) and abnormal total motility (OR: 1.53; 95%CI: 1.06, 2.19), with this association primarily driven by Li, Mg, and Zn. In summary, our findings indicate that exposure to metal/metalloid mixtures might have an adverse effect on semen quality.

Dietary Egg White Hydrolysate Prevents Male Reproductive Dysfunction after Long-Term Exposure to Aluminum in Rats

Aluminum (Al) is a non-essential metal omnipresent in human life and is considered an environmental toxicant. Al increases reactive oxygen production and triggers immune responses, contributing to chronic systemic inflammation development. Here, we have tested whether an egg white hydrolysate (EWH) with potential bioactive properties can protect against changes in reproductive function in rats exposed to long-term Al dietary levels at high and low doses. Male Wistar rats received orally: low aluminum level group-AlCl₃ at 8.3 mg/kg b.w. for 60 days with or without EWH (1 g/kg/day); high aluminum level group-AlCl₃ at 100 mg/kg b.w. for 42 days with or without EWH (1 g/kg/day). The co-administration of EWH prevented the increased Al deposition surrounding the germinative cells, reducing inflammation and oxidative stress in the reproductive organs. Furthermore, the daily supplementation with EWH maintained sperm production and sperm quality similar to those found in control animals, even after Al exposure at a high dietary contamination level. Altogether, our results suggest that EWH could be used as a protective agent against impairment in the reproductive system produced after long-term exposure to Al at low or high human dietary levels.

Observable Protective Activities of Quercetin on Aluminum Chloride-Induced Testicular Toxicity in Adult Male Wistar Rat

Background:

Aluminum chloride (AlCl3 ) present in many manufactured consumable is considered as a toxic element.

Aim:

Our study evaluates the toxic effects induced by AlCl3 on the testes as well as the therapeutic tendency of Quercetin (QUE) agent as an antioxidant.

Setting and Design:

In the department of Anatomy of Medical School.

Methods and Materials:

Thirty-two male Wistar rats weighing approximately 170 ± 10 g were assigned into four groups with eight each, fed with rat chow and water ad-libitum. Group A served as control and was given distilled water throughout; Group B was given only QUE (200 mg/kg body weight) for 21 days; Group C was given only AlCl3 (300 mg/kg body weight) for 14 days; and Group D was given AlCl3 (300 mg/kg body weight) for 14 days followed with QUE (200 mg/kg body weight) for 21 days. Substance administrations were done orally.

Statistical analysis:

One-way analysis of variance was used to analyze the data, in GraphPad Prism 6.0 being the statistical software.

Results:

AlCl3 significantly reduced the relative organ (testes) weight, correlating the decrease in sperm count, sperm motility and sperm viability. Furthermore, there was a decrease in luteinizing hormone with an increase in follicle-stimulating hormone which accounted for a significant reduction in testosterone level that plays a great role in spermatogenesis, following AlCl3 treatment. The cytoarchitecture of the testes showed degenerative changes in the seminiferous tubules and leydin cells, nitric oxide synthases immunoreactivity was intense in the seminiferous epithelium of rat in Group C.

Conclusion:

These suggest that QUE antioxidant property could reverse the decrease in sperm status, hormonal effects, and functional deficit induced by aluminum chloride on the testes of Wistar rats.

Effect of Copper Sulphate and Cadmium Chloride on Non-Human Primate Sperm Function In Vitro

In order to address the large percentage of unexplained male infertility in humans, more detailed investigations using sperm functional tests are needed to identify possible causes for compromised fertility. Since many environmental and lifestyle factors might be contributing to infertility, future studies aiming to elucidate the effect of such factors on male fertility will need the use of appropriate research models. The current study aimed to assess the effects of two heavy metals, namely copper sulphate, and cadmium chloride, on non-human primate (NHP) sperm function in order to establish the possibility of using these primate species as models for reproductive studies. Our combined results indicated that the functionality of NHP spermatozoa is inhibited by the two heavy metals investigated. After in vitro exposure, detrimental effects, and significant lowered values (p < 0.05) were obtained for sperm motility, viability and vitality, acrosome intactness, and hyperactivation. These metals, at the tested higher concentrations, therefore, have the ability to impair sperm quality thereby affecting sperm fertilizing capability in both humans and NHPs.

Trace element analysis of human seminal plasma: A cautionary tale of preanalytical variation and use of non-traditional matrices in human biomonitoring studies

Ensuring harmonization of (ultra-)trace element measurements in non-traditional matrices is a particular analytical challenge that is highlighted in this work for seminal plasma as part of the developmental core at the Wadsworth Center Human Health Exposure Analysis Resource Targeted Laboratory. Seminal plasma was collected from 39 male partners of women undergoing in vitro fertilization and analyzed by inductively coupled plasma tandem mass spectrometry (ICP-MS/MS) following deproteinization with concentrated HNO₃. Validation was accomplished using: 1) two aqueous NIST SRMs; 2) a seminal plasma QC pool, characterized via standard additions; 3) standard additions on a subset of samples; and 4) sample duplicates. Agreement with NIST certified or reference values were obtained to within ±15% for the SRMs, and agreement between aqueous calibration values and standard additions values agreed to within ±10-20% for all elements. Standard additions of seminal plasma samples revealed varying matrix effects for Cu and Cr that were not found for the pooled samples. Duplicate analyses agreed to within ±10-30% depending on element. A potential source of contamination in colloidal silica used for processing seminal plasma was identified that requires further study. Comparisons with literature indicate lack of consensus for As, Cd, Cr, Mn, Pb, and V content in seminal plasma. Further work is needed to improve harmonization of future studies.

Impact of aluminium toxicity on vital human sperm parameters-Protective effects of silymarin

Aluminium is an environmental pollutant which induces oxidative stress, while silymarin is a potent antioxidant. This study was conducted to investigate the possible protective effects of silymarin on adverse effects of aluminium chloride on vital sperm parameters as well as its effects on oxidative stress markers in human spermatozoa. Human spermatozoa were divided into 5 groups as follows: (a) spermatozoa at 0 hr; (b) spermatozoa at 180 min (control); (c) spermatozoa treated with aluminium chloride; (d) spermatozoa treated with silymarin + aluminium chloride; and (e) spermatozoa treated with silymarin. The sperm samples were used to assess sperm vital parameters such as acrosome and plasma membrane integrity, viability, mitochondrial membrane potential (MMP) and motility as well as sperm malondialdehyde (MDA) level and the total antioxidant capacity. The percentage of acrosome and plasma membrane integrity, viability, MMP, motility and the total antioxidant capacity of spermatozoa treated with aluminium chloride significantly decreased compared with control group, while the level of MDA significantly increased compared with the control group. In the silymarin + aluminium chloride group, silymarin could significantly compensate the adverse effects of aluminium chloride on these parameters. Administration of silymarin alone significantly increased the percentage of acrosome and plasma membrane integrity, viability, motility and total antioxidant capacity, while significantly reduced MDA levels compared with the control group. Aluminium chloride by inducing oxidative stress exerts disastrous effects on the vital parameters of human spermatozoa and silymarin, as a potent antioxidant, could reverse the effects of aluminium chloride on these parameters.

Aluminum reproductive toxicity: a summary and interpretation of scientific reports

Publications addressing aluminum (Al)-induced reproductive toxicity were reviewed. Key details were compiled in summary tables. Approximate systemic Al exposure, a measure of bioavailability, was calculated for each exposure, based on the Al percentage in the dosed Al species, Al bioavailability, and absorption time course reports for the exposure route. This was limited to laboratory animal studies because no controlled-exposure human studies were found. Intended Al exposure was compared to unintended dietary Al exposure. The considerable and variable Al content of laboratory animal diets creates uncertainty about reproductive function in the absence of Al. Aluminum-induced reproductive toxicity in female mice and rats was evident after exposure to ≥25-fold the amount of Al consumed in the diet. Generally, the additional daily Al systemic exposure of studies that reported statistically significant results was greater than 100-fold above the typical human daily Al dietary consumption equivalent. Male reproductive endpoints were significantly affected after exposure to lower levels of Al than females. Increased Al intake increased fetus, placenta, and testes Al concentrations, to a greater extent in the placenta than fetus, and, in some cases, more in the testes than placenta. An adverse outcome pathway (AOP) was constructed for males based on the results of the reviewed studies. The proposed AOP includes oxidative stress as the molecular initiating event and increased malondialdehyde, DNA and spermatozoal damage, and decreased blood testosterone and sperm count as subsequent key events. Recommendations for the design of future studies of reproductive outcomes following exposure to Al are provided.

No Correlation between Blood Benzene Levels and Luteinizing Hormone Plasma Values in Outdoor Workers

OBJECTIVE

The purpose of the study is to evaluate whether low-dose exposure to benzene, an environmental pollutant to which male and female traffic policemen are daily exposed to could cause alterations in plasma luteinizing hormone (LH) levels.

METHODS

From an initial sample of 1594 workers, we only selected 95 workers of whom study we knew the values of late-shift benzene and LH hormone. All subjects underwent biological monitoring (final blood benzene evaluation) and luteinizing hormone dosing. Excluding subjects with the main confounding factors, the final sample included 76 workers. The normal distribution of the variables was evaluated using the Kolmogorov - Smirnov test, followed by the logarithmic transformation of the LH and benzene values. The comparison among means was performed by using the t-test for the independent samples. The ANOVA test was performed for variables with more than 2 modes (ages and seniority) and Pearson correlation index between variables in the total sample and after subdivision as to sex, job, sports activity and smoking. The results were considered significant when p values were less than 0.05.

RESULTS/CONCLUSION

The study did not show a correlation between benzene levels and LH plasma levels in outdoor workers.

Quantitative assessment of heavy metal effects on sperm function using computer-aided sperm analysis and cytotoxicity assays

One known environmental risk factor impacting on human reproduction is heavy metal pollution. Although some metals (e.g., Cu, Se and Zn) have protective effects on the male reproductive system in low doses, heavy metals can accumulate to toxic levels and result in poor semen quality and decreased sperm function. We investigated the effect of CuSO₄ and CdCl₂ (10, 50, 100 and 250 µg/ml or 500 µg/ml) on human sperm motility and vitality by using computer-aided sperm analysis (CASA) and two cytotoxicity assays (WST-1 and XTT). Several sperm motility parameters were significantly reduced after 5 hr of exposure to the highest concentrations of CuSO₄ (250 µg/ml) and CdCl₂ (500 µg/ml). The WST-1 assay also revealed significantly lower absorbance values for 50, 100 and 250 µg/ml CuSO₄ and for 500 µg/ml CdCl₂ ; however, no significant effect was seen with XTT. The calculated average IC₅₀ value was 50.31±  4.34 µg/ml for CuSO₄ and 392.32  ±76.79 µg/ml for CdCl₂ . The effects of these metals were confirmed with MgCl₂ , a positive control. This study provides threshold concentrations for the harmful effect of CuSO₄ and CdCl₂ on human spermatozoa and recommends the use of WST-1 as vitality assay in future in vitro studies.

Associations of semen quality with non-essential heavy metals in blood and seminal fluid: data from the Environment and Male Infertility (EMI) study in Lebanon

BACKGROUND

Human exposure to environmental pollutants is widespread. It was suggested that exposure to non-essential heavy metals may adversely affect semen development in men.

PURPOSE

To evaluate associations between non-essential heavy metals in blood and seminal fluid and semen quality parameters in men.

METHODS

Male partners of heterosexual couples were included. The following elements were measured in blood and seminal fluid: lead (Pb), cadmium (Cd), arsenic (As), barium (Ba), mercury (Hg), and uranium (U) using ion-coupled plasma-mass spectrometry.

SETTING

The fertility clinic at the American University of Beirut Medical Center.

MAIN OUTCOME MEASURES

Semen quality parameters (volume, concentration, total count, progressive motility, viability, and normal morphology).

RESULTS

We found that participants with low-quality semen had significantly higher Cd and Ba concentrations in the seminal fluid than participants with normal-quality semen. We also observed significant associations between low sperm viability and higher blood Cd and Ba, as well as higher seminal Pb, Cd, Ba, and U. Furthermore, U concentrations in the seminal fluid were associated with increased odds ratios for below-reference progressive sperm motility and normal morphology.

CONCLUSIONS

Environmental exposures to Pb, Cd, Ba, and U appear to adversely influence sperm development in men. In non-occupationally exposed men, measurements of heavy metals in the seminal fluid may be more predictive of below-reference sperm quality parameters than in blood.

A Preliminary Study about the Potential Effects of Heavy Metals on the Human Male Reproductive Parameters in HIV-Infected Population in China

Due to the inconsistent effects of human immunodeficiency virus (HIV) on the human male reproduction in previous studies and the impacts of environmental exposures, such as heavy metals, on male reproduction receiving little attention in HIV-infected population, the aim of present study was to investigate whether heavy metals have potential effects on reproductive parameters in HIV-infected men. The current study assessed the associations between semen quality or serum hormone and concentration of the three heavy metal toxicants (lead (Pb), cadmium (Cd), and zinc (Zn)) in seminal, urine, and serum, and 50 HIV-infected men were recruited in the present study. Concentrations of Pb, Cd, and Zn were measured in three fluids by graphite furnace atomic absorption spectrophotometer. Semen analyses were performed according to World Health Organization criteria. Serum samples were analyzed for follicle-stimulating hormone, luteinizing hormone, and testosterone. HIV RNA viral load was determined by HIV virus loads kit. Spearman's rank correlations were used for correlation analyses. The results showed that the concentrations of Pb, Cd, and Zn were significantly correlated with semen quality and serum hormone. HIV-1 virus loads were significantly associated with increased seminal Pb. However, HIV-1 virus loads were not statistically associated with semen quality and serum hormone. Our findings suggested that environmental heavy metals had potential effects on reproductive parameters in HIV-infected men in China.

Lead, selenium and nickel concentrations in epithelial ovarian cancer, borderline ovarian tumor and healthy ovarian tissues

OBJECTIVE

Wide variation exists in ovarian cancer incidence rates suggesting the importance of environmental factors. Due to increasing environmental pollution, trace elements and heavy metals have drawn attention in studies defining the etiology of cancer, but scant data is available for ovarian cancer. Our aim was to compare the tissue concentrations of lead, selenium and nickel in epithelial ovarian cancer, borderline tumor and healthy ovarian tissues.

METHODS

The levels of lead, selenium and nickel were estimated using atomic absorption spectrophotometry in formalin-fixed paraffin-embedded tissue samples. Tests were carried out in 20 malignant epithelial ovarian cancer, 15 epithelial borderline tumor and 20 non-neoplastic healthy ovaries. Two samples were collected for borderline tumors, one from papillary projection and one from the smooth surface of cyst wall.

RESULTS

Pb and Ni concentrations were found to be higher both in malignant and borderline tissues than those in healthy ovaries. Concentrations of Pb and Ni in malignant tissues, borderline papillary projections and capsular tissue samples were not different. Comparison of Se concentrations of malignant, borderline and healthy ovarian tissues did not reveal statistical difference. Studied metal levels were not found to be different in either papillary projection or in cyst wall of the borderline tumors.

CONCLUSIONS

This study revealed the accumulation of lead and nickel in ovarian tissue is associated with borderline and malignant proliferation of the surface epithelium. Accumulation of these metals in epithelial ovarian cancer and borderline ovarian tumor has not been demonstrated before.

Aluminum exposure for 60days at human dietary levels impairs spermatogenesis and sperm quality in rats

Concerns about environmental aluminum (Al) and reproductive health have been raised. We investigated the effects of Al exposure at a human relevant dietary level and a high level exposure to Al. Experiment 1 (Lower level) rats were treated orally for 60 days: a) controls - ultrapure water; b) aluminum at 1.5mg/kg bw/day and c) aluminum at 8.3mg/kg bw/day. Experiment 2 (High level) rats were treated for 42 days: a) controls - ultrapure water; b) aluminum at 100mg/kg bw/day. Al decreased sperm count, daily sperm production, sperm motility, normal morphological sperm, impaired testis histology; increased oxidative stress in reproductive organs and inflammation in testis. Our study shows the specific presence of Al in the germinative cells and, that low concentrations of Al in testes (3.35μg/g) are sufficient to impair spermatogenesis and sperm quality. Our findings provide a better understanding of the reproductive health risk of Al.

The environment and male reproduction: The effect of cadmium exposure on reproductive function and its implication in fertility

Cadmium is an environmental pollutant known as endocrine disruptor. Testis is particularly susceptible to cadmium, and testis injury occurs at high but even low levels of exposure. Cadmium reproductive toxicity is mediated by multiple mechanisms, including structural damage to testis vasculature and blood-testis barrier, inflammation, cytotoxicity on Sertoli and Leydig cells, oxidative stress mainly by means of mimicry and interference with essential ions, apoptosis, interference with selected signaling pathways and epigenetic regulation of genes involved in the regulation of reproductive function, and disturbance of the hypothalamus-pituitary-gonadal axis. The current review outlines epidemiological observational findings from environmental and occupational exposure in humans, and reports experimental studies in humans and animals. Lastly, a focus on the pathogenetic mechanisms of cadmium toxicity and on the specific mechanisms of cadmium sensitivity and resistance, particularly assessed in animal models, is included. Despite convincing experimental findings in animals and supporting evidences in humans identifying cadmium as reproductive toxicant, observational findings are controversial, suffering from heterogeneity of study design and pattern of exposure, and from co-exposure to multiple pollutants.

The Effect of Aluminum Exposure on Reproductive Ability in the Bank Vole (Myodes glareolus)

Human impact on the environment is steadily increasing the amounts of aluminum in the ecosystems. This element accumulates in plants and water, potentially exposing herbivores to its harmful effect. In heavily polluted sites, a decrease in the density of small rodent populations has been observed. This decline may be caused by many factors, including decreased fertility. The aim of the presented research was to determine how aluminum, administered at concentrations similar to those recorded in industrial districts (Al I = 3 mg/l, Al II = 200 mg/l), affects the reproductive abilities of small rodents. As the indicators of reproductive abilities, body weight, weight of the testes and accessory sex glands of males, and uterus weight of females were estimated. In females, the number of matured follicles (types 6, 7, and 8) was analyzed, while in males, the quantity and quality (matured, viable, swollen, motile, head abnormalities) of epididymal sperm cells were assessed. Moreover, the development of testes, measured by spermatogenic index, was determined. The model species was the bank vole. Our results have proven that aluminum impairs adult individuals' reproductive abilities by decreasing the quality and quantity of sperm cells and by causing morphologically abnormal development of the gonads. However, no difference in male organometric parameters was found, and only in females treated with 3 mg/l Al, the uterus weight was higher than control. No differences were found in the total number of matured follicles. These results suggest that the decline in rodent numbers in industrial districts is due, at least in part, to poorer males' reproductive abilities, resulting from exposure to aluminum contamination.

Human Sperm Quality and Metal Toxicants: Protective Effects of some Flavonoids on Male Reproductive Function

Background

Metals can cause male infertility through affection of spermatogenesis and sperm quality. Strong evidences confirm that male infertility in metal-exposed humans is mediated via various mechanisms such as production of reactive oxygen species (ROS). Flavonoids have antioxidant and metal chelating properties which make them suitable candidates for neutralizing adverse effects of metals on semen quality. In the current study, we have evaluated the effects of five types of flavonoids (rutin, naringin, kaempferol, quercetin, and catechin) on recovery of sperm motility and prevention of membrane oxidative damage from aluminum chloride (AlCl₃), cadmium chloride (CdCl₂), and lead chloride (PbCl₄).

Materials and Methods

In this experimental study, motility and lipid peroxidation of metalexposed sperm was investigated in the presence of different concentrations of five kinds of flavonoids. Malondialdehyde (MDA) production was assessed as a lipid peroxidation marker.

Results

Aluminum chloride (AlCl₃), cadmium chloride (CdCl₂), and lead chloride (PbCl₄) diminished sperm motility. Treatment of metal-exposed sperm with rutin, naringin, and kaempferol attenuated the negative effects of the metals on sperm motility. Quercetin and catechin decreased the motility of metal-exposed sperm.

Conclusion

Based on the MDA production results, only AlCl₃ significantly induced lipid peroxidation. Treatment with rutin, naringin, and kaempferol significantly decreased MDA production.

Role of low exposure to metals as male reproductive toxicants

The objective of the study was to examine the associations between environmentally relevant low metal concentrations and semen quality parameters in men. The concentrations of zinc (Zn), copper (Cu), cadmium (Cd), arsenic (As), selenium (Se), and lead (Pb) in the seminal plasma and urine were measured from 196 male human subjects in Taiwan. Urinary Cd concentrations were negatively associated with sperm viability (p = 0.006). Seminal plasma Cu concentrations of the normal group (≥ 15 × 10(6)/ml) were significantly lower than those of the abnormal group (p = 0.023). However, the linear regression analysis showed a weak association between Cu concentration and sperm concentration, along with other semen parameters. No significant relationship between other metals (As, Pb, Zn, and Se) and semen quality was observed.

Inhibition of key markers linked with spermatogenesis and cellular ATP by subchronic exposure to leachate in a rat model

Few or no studies have measured the toxic effects of subchronic exposure to leachate using key markers linked with spermatogenesis and cellular adenosine triphosphate (ATP) in an experimental rat model. This study was undertaken to evaluate the toxic effects of leachate obtained from the Elewi Odo municipal battery-recycling site (EOMABRL) on male reproductive function using testicular hormones and biomarker of cellular ATP. EOMABRL was administered at 0, 20, 40, 60, 80, and 100% concentrations to adult male rats for 60 days. After exposure, serum was collected for hormonal biochemistry assays, and testes were collected to determine the activity of xanthine oxidase (XO) and lactate dehydrogenase (LDH). Exposure of animals to EOMABRL resulted in a 519.7, 285.7, 569.1, 606.1, and 1,793.2% increase in XO activity with a sequential decrease in LDH activity (marker of cellular ATP) by 44.1, 55.9, 61.4, 69.3, and 89.7%, respectively, compared with the control. Furthermore, EOMABRL caused a significant inhibitory effect on serum luteinizing hormone, follicle-stimulating hormone, and testosterone levels. We conclude that some possible mechanisms by which EOMABRL elicits toxicity in male rat testes could be through inhibition of LDH activity and depletion of serum hormone levels.

Relationships between heavy metal concentrations in three different body fluids and male reproductive parameters: a pilot study

BACKGROUND

Animal studies have shown the reproductive toxicity of a number of heavy metals. Very few human observational studies have analyzed the relationship between male reproductive function and heavy metal concentrations in diverse biological fluids.

METHODS

The current study assessed the associations between seminal and hormonal parameters and the concentration of the 3 most frequent heavy metal toxicants (lead, cadmium and mercury) in three different body fluids. Sixty one men attending infertility clinics that participated in a case-control study to explore the role of environmental toxins and lifestyles on male infertility were analyzed. Concentration of lead, cadmium and mercury were measured in blood and seminal plasma and whole blood using anodic stripping voltammetry and atomic absorption spectrophotometry. Serum samples were analyzed for follicle-stimulating hormone, luteinizing hormone and testosterone. Semen analyses were performed according to World Health Organization criteria. Mann-Whitney test and Spearman's rank correlations were used for unadjusted analyses. Multiple linear regression models were performed controlling for age, body mass index and number of cigarettes per day.

RESULTS

There were no significant differences between cases and controls in the concentrations of heavy metals in any of the three body fluids. In multivariate analyses using all subjects no significant associations were found between serum hormone levels and metal concentrations. However there was a significant positive association between the percentage of immotile sperms and seminal plasma levels of lead and cadmium.

CONCLUSIONS

Our results suggest that the presence of lead and cadmium in the reproductive tract of men may be related to a moderate alteration of their seminal parameters.

Cadmium concentrations in blood and seminal plasma: correlations with sperm number and motility in three male populations (infertility patients, artificial insemination donors, and unselected volunteers)

To investigate a possible common environmental exposure that may partially explain the observed decrease in human semen quality, we correlated seminal plasma and blood cadmium levels with sperm concentration and sperm motility. We studied three separate human populations: group 1, infertility patients (Long Island, NY, USA); group 2, artificial insemination donors (AID) (Rochester, NY, USA); and group 3, general population volunteers (Rochester, NY, USA). Information about confounding factors was collected by questionnaire. Seminal plasma cadmium did not correlate with blood cadmium (Spearman correlation, n = 91, r = -0.092, P = 0.386, NS). Both blood and seminal plasma cadmium were significantly higher among infertility patients than the other subjects studied (for example, median seminal plasma cadmium was 0.282 microg/L in infertility patients versus 0.091 microg/L in AID and 0.092 microg/L in general population volunteers; Kruskal-Wallis test, P < 0.001). The percentage of motile sperm and sperm concentration correlated inversely with seminal plasma cadmium among the infertility patients (r = -0.201, P < 0.036 and r = -0.189, P < 0.05, respectively), but not in the other two groups. Age (among infertility patients) was the only positive confounder correlating with seminal plasma cadmium. To validate our human findings in an animal model, we chronically exposed adolescent male Wistar rats to low-moderate cadmium in drinking water. Though otherwise healthy, the rats exhibited decreases in epididymal sperm count and sperm motility associated with cadmium dose and time of exposure. Our human and rat study results are consistent with the hypothesis that environmental cadmium exposures may contribute significantly to reduced human male sperm concentration and sperm motility.

Luteinizing hormone (LH) levels in male workers exposed to urban stressors

The aim of the study is to evaluate if occupational exposure to urban stressors could cause alterations in luteinizing hormone (LH) plasma levels in male traffic policemen vs. administrative staff of Municipal Police.After excluding the subjects with the main confounding factors, male traffic police and administrative staff of Municipal Police were matched by age, working life, body mass index (BMI), alcohol drinking habit, cigarette smoking habit and habitual consumption of Italian coffee.In 166 male traffic police mean LH values were significantly higher compared to 166 male administrative employees. The distribution of LH values in traffic police and in administrative employees was statistically significant.Our results suggest that recent exposure to urban stressors (chemical, physical and psycho-social) can alter the plasma concentration of LH. In agreement with our previous research, levels of plasma LH may be used as early biological markers, valuable for the group, used in occupational set before the appearance of the disease.

Cadmium, lead, and other metals in relation to semen quality: human evidence for molybdenum as a male reproductive toxicant

BACKGROUND

Evidence on human semen quality as it relates to exposure to various metals, both essential (e.g., zinc, copper) and nonessential (e.g., cadmium, lead), is inconsistent. Most studies to date used small sample sizes and were unable to account for important covariates.

OBJECTIVES

Our goal in this study was to assess relationships between exposure to multiple metals at environmental levels and human semen-quality parameters.

METHODS

We measured semen quality and metals in blood (arsenic, Cd, chromium, Cu, Pb, manganese, mercury, molybdenum, selenium, and Zn) among 219 men recruited through two infertility clinics. We used multiple statistical approaches to assess relationships between metals and semen quality while accounting for important covariates and various metals.

RESULTS

Among a number of notable findings, the associations involving Mo were the most consistent over the various statistical approaches. We found dose-dependent trends between Mo and declined sperm concentration and normal morphology, even when considering potential confounders and other metals. For example, adjusted odds ratios (ORs) for below-reference semen-quality parameters in the low, medium, and high Mo groups were 1.0 (reference), 1.4 [95% confidence interval (CI), 0.5-3.7], and 3.5 (95% CI, 1.1-11) for sperm concentration and 1.0 (reference), 0.8 (95% CI, 0.3-1.9), and 2.6 (95% CI, 1.0-7.0) for morphology. We also found preliminary evidence for interactions between Mo and low Cu or Zn. In stratified analyses, the adjusted ORs in the high Mo/low Cu group were 14.4 (1.6, 132) and 13.7 (1.6, 114) for below-reference sperm concentration and morphology, respectively.

CONCLUSIONS

Our findings represent the first human evidence for an inverse association between Mo and semen quality. These relationships are consistent with animal data, but additional human and mechanistic studies are needed.

An in vitro study on reproductive toxicity of aluminium chloride on rabbit sperm: The protective role of some antioxidants

An in vitro study using rabbit sperm was designed to evaluate the cytotoxic effects of different concentrations of aluminium chloride (AlCl(3)) at 0, 2 and 4h of incubation on sperm motility and viability, oxidative status and the activities of some antioxidant enzymes (superoxide dismutase (SOD) and catalase (CAT)), transaminases and acid phosphatase. The role of vitamin C (1 mM) or vitamin E (2 mM) was also investigated in counteracting deterioration caused by AlCl(3) on the tested parameters. Rabbit sperm was incubated with different concentrations of AlCl(3) (0, 1, 5, 10, 15 and 20 mM) with or without vitamin C or vitamin E for 2 and 4 h. Results revealed that the percentage of motile and viable sperm decreased significantly after AlCl(3) treatment at 10, 15 and 20 mM and the response was both concentration and time dependent. Aluminium chloride at concentrations of 10, 15 and 20 mM caused significant induction of oxidative stress as evidenced by increased thiobarbituric acid reactive substances (TBARS) levels and inhibition in the activities of SOD and CAT. Increase in the activities of aspartate transaminase (AST) and alanine transaminase (ALT) and decline in the activity of acid phosphatase (ACP) were also observed at AlCl(3) concentrations of 15 and 20 mM. Co-incubation with either vitamin C or vitamin E resulted in marked degrees of protection against AlCl(3)-induced cytotoxic effects, represented in decreased TBARS levels and restoration of enzymes activities near control. On the other hand, no significant effect was exerted from vitamin C or vitamin E on motility and viability. The present study demonstrated that AlCl(3) caused deterioration in sperm motility and viability, enhancement of free radicals and alterations in enzymes activities. The antioxidants revealed protective effects against the cytotoxicity of AlCl(3).

Plasma 17-alpha-OH-progesterone in male workers exposed to traffic pollutants

The aim of the study is to evaluate if the occupational exposure to urban pollutants could cause alterations on 17-alfa-hydroxy-progesterone plasma levels and related diseases in male traffic policemen. 17-alpha-OH-P is synthesized in Leydig cells and in adrenals; it influences spermiogenesis, acrosoma reaction, testosterone biosynthesis, blocking of gonadotropin secretion; it regulates learning, memory and sleep. After excluding principal confounding factors, i.e., rotating or night shifts, exposure to solvents, paints and pesticides during time-off and smoking, traffic policemen were matched with controls by age, working life and drinking habit. Finally, 112 traffic policemen and 112 controls were included in the study. In traffic policemen 17-alpha-OH-P mean values were significantly higher vs. controls. The distribution of 17-alpha-OH-P values in both groups was significant. An increased frequency of fertility disorders referred to the questionnaire items were found in traffic policemen vs. controls, but the difference was not significant. The occupational exposure to low doses of chemical urban stressor, interacting with and adding to the psychosocial ones, could alter plasma 17-alpha-OH-P concentrations in traffic policemen vs. controls. 17-alpha-OH-P could be used as an early biological marker, even before the onset of the reproductive and mental health diseases.

Effects of peritoneal aluminum overload on polyamines and nitric oxide contents of testes and epididymis in the mice

Polyamines are involved in cellular growth, differentiation and regulation of oxidative stress. The present investigation was to determine the effect of aluminum (Al) toxicity on the nitric oxide products (NO(x)) and metabolism of polyamines in mouse testes and epididymis. Aluminum chloride, AlCl(3,) was administered intraperitoneally to CD-1 adult male mice at dosages of 0, 7 or 35mg Al/kg body weight/day for 14 days (C, LAL and HAL groups). Results obtained show that the weights of epididymis in HAL animals are significantly decreased due to Al administration. Al treatment significantly induced higher Al concentrations in serum, testis and epididymis tissue. In addition, the serum and testicular and epididymal NO(x) production in HAL and testicular NO(x) in LAH groups were increased remarkably compared to the control animals. On the contrary, the contents of putrescine and spermine in testis were significantly lower than the values of controls and LAL groups. The epididymal spermine levels of HAL animal also decreased significantly. It is suggested that the polyamine biosynthesis in the mouse testis and epididymis can be affected by Al, which is associated with the NO(x) production in the male reproductive toxicity.

Aluminium-induced deterioration in reproductive performance and seminal plasma biochemistry of male rabbits: Protective role of ascorbic acid

Aluminium (Al) has been proposed as an environmental factor that may contribute to some diseases, affect several enzymes and other biomolecules and induced free radical-mediated cytotoxicity. Also, Al induced reproductive toxicity and exerted a significant adverse effect on the steroidogenesis. The antioxidant ascorbic acid (AA) plays an important role in various physiological processes in the body including detoxification of different toxic materials. Therefore, the present investigation aimed to elucidate possible protective effects of AA in alleviating the toxicity of aluminium chloride (AlCl3) on reproductive performance, lipid peroxidation and enzyme activities in seminal plasma of male New Zealand white rabbits. Six rabbits per group were assigned to one of four treatment groups: 0 mg AA and 0 mg AlCl3 /kg body weight (BW) (control); 40 mg AA/kg BW; 34 mg AlCl3 /kg BW; 34 mg AlCl3 plus 40 mg AA/kg BW. Rabbits were orally administered their respective doses every other day for 16 weeks. Results obtained showed that AlCl3 significantly (P<0.05) decreased libido (by increasing the reaction time), ejaculate volume, sperm concentration, total sperm output, sperm motility (%), total motile sperm per ejaculate (TMS), packed sperm volume (PSV), total functional sperm fraction (TFSF), normal and live sperm and semen initial fructose. While initial hydrogen ion concentration (pH) and dead and abnormal sperm were increased (P<0.05). Live body weight (LBW), feed intake (FI) and relative weights of testes (RTW) and epididymis (REW) were significantly (P<0.05) decreased. Concentrations of thiobarbituric acid-reactive substances (TBARS) were significantly (P<0.05) increased in seminal plasma of rabbits treated with AlCl3 compared with control. While, activities of glutathione S-transferase (GST), aspartate aminotransferase (AST), alanine aminotransferase (ALT) and acid phosphatase (AcP) were significantly (P<0.05) decreased. Ascorbic acid alone significantly increased LBW, FI, RTW, REW, semen characteristics and seminal plasma enzymes, and decreased the levels of free radicals. Also, the present study showed that ascorbic acid might be effective in the protection of aluminium-induced reproductive toxicity. It was suggested that AlCl3 exerted a significant adverse effect on reproductive performance of male rabbits. Furthermore, AA could be able to antagonize the toxic effects of AlCl3 and improved semen quality of male rabbit.

The effect of heavy metal exposure on egg size, eggshell thickness and the number of spermatozoa in blue tit Parus caeruleus eggs

In this study we compared the egg size, the eggshell thickness and the number of spermatozoa trapped on the perivitelline layer of the eggs in three blue tit (Parus caeruleus) populations across a heavy metal pollution gradient. No significant differences were observed in egg characteristics among study sites. Eggs from the two most polluted sites however, had significantly less spermatozoa on the perivitelline layer than eggs from the least polluted site. Our results suggest a significant effect of pollution on blue tit sperm concentrations in the infundibulum. Determining the number of spermatozoa on the egg membranes is relatively cheap and straightforward, which renders this technique a new and useful tool in biomonitoring.

Occupational Exposure Associated with Reproductive Dysfunction

Evidence suggestive of harmful effects of occupational exposure on the reproductive system and related outcomes has gradually accumulated in recent decades, and is further compounded by persistent environmental endocrine disruptive chemicals. These chemicals have been found to interfere with the function of the endocrine system, which is responsible for growth, sexual development and many other essential physiological functions. A number of occupations are being reported to be associated with reproductive dysfunction in males as well as in females. Generally, occupations involving the manufacture/or application of some of the persistent chemicals that are not easily degradable as well as bio-accumulative chemicals, occupations involving intensive exposure to heat and radiation, occupations involving the use of toxic solvents as well as toxic fumes are reported to be associated with reproductive dysfunction. Occupational exposure of males to various persistent chemicals have been reported to have male mediated adverse reproductive outcomes in the form of abortion, reduction in fertility etc. with inconclusive or limited evidence. Nevertheless, there is a need for more well designed studies in order to implicate any individual chemical having such effects as in most occupations workers are exposed to raw, intermediate and finished products and there are also several confounding factors associated with lifestyles responsible for reproductive dysfunction. There is an urgent need to look at indiscriminate use of persistent chemicals especially pesticides and persistent organic pollutants (POP's) as these chemicals enter the food chain also and could be potential for exposure during the critical period of development. It is also necessary to impart information, and to educate about the safe use of these chemicals, as a very sensitive reproduction issue is involved with exposure to these chemicals. Occupational exposures often are higher than environmental exposures, so that epidemiological studies should be conducted on these chemicals, on a priority basis, which are reported to have adverse effects on reproduction in the experimental system.

Expression of Constitutive Endothelial, Neuronal and Inducible Nitric Oxide Synthase in the Testis and Epididymis of Horse

The expression of three isoforms of nitric oxide synthase (NOS) were examined in the testis and epididymis of a thoroughbred horse. Immunohistochemical studies demonstrated the presence of eNOS immunostaining in some germ cells in the seminiferous tubules and in vascular endothelial cells in the interstitial tissues. Interstitial cells, most likely Leydig cells, were also intensely immunopositive for eNOS. The pattern of immunostaining for nNOS was similar to that for eNOS in the testis. Weak expression of iNOS was detected in the seminiferous tubules of the testis, but intense expression was found in interstitial cells. Inducible NOS was also strongly detected in stereocilia, sperm, epithelium and connective tissue of the epididymis of normal horses. These findings suggest that three isoforms of NOS are expressed in the testis and epididymis of horse and that they play important roles in the biology of interstitial cells that produce testosterone, as well as in spermatogenesis in the seminiferous tubules.

Serum and testicular testosterone and nitric oxide products in aluminum-treated mice

The present investigation aimed to elucidate possible mechanisms of aluminum (Al)-induced reproductive toxicity in male mice. Daily intraperitoneal administrations of Al chloride (0, 1/8 and 1/3 LD(50)) were conducted for 12 or 16 days, followed by a 2-week withdrawal period. Serum Al levels significantly increased in Al-treated animals, compared to controls, whereas serum testosterone concentrations were markedly decreased. In addition, significant increases in nitric oxide products (NO(x)) were also observed during Al injection. Similar trends were found for testicular Al, NO(x) and testosterone levels. However, during the withdrawal period, when diminished testicular Al levels were observed, the changes in NO(x) and testosterone levels were indistinguishable from control values. It was concluded that: (i) Al exerted a significant adverse effect on the steroidogenesis; (ii) the process was reversible; and (iii) increased production of NO(x), induced by excessive Al, might inhibit testosterone levels.