Seminal plasma lead, cadmium and zinc in relation to tobacco consumption

Redox Regulation to Modulate Phosphorylation Events in Human Spermatozoa

Significance: Spermatozoa are complex and compartmentalized cells that undergo capacitation, a series of biochemical and morphological changes to acquire the ability to fertilize oocytes. Reactive oxygen species (ROS) have a prominent dual role in capacitation. At physiological levels, ROS regulate numerous cellular processes, including increases of cyclic adenosine monophosphate, calcium, and activation of phosphorylation events needed for capacitation. On the contrary, at high concentrations that do not impair sperm viability, ROS can cause loss of motility and inhibition of capacitation. Higher ROS concentrations promote oxidation of lipids, proteins, and DNA leading to cell death, and these damages have been associated with male infertility. Critical Issues: When incubated under specific conditions, spermatozoa can produce low and controlled amounts of ROS that are not harmful but instead regulate numerous cellular processes, including the phosphorylation of tyrosine, serine, and threonine residues in critical proteins needed for sperm capacitation. Here, we outline the complex redox signaling in human spermatozoa needed to achieve fertility and the role of ROS as physiological mediators that trigger phosphorylation cascades. Moreover, we illustrate the importance of various phosphoproteins in spermatozoa capacitation, viability, and hyperactive motility. Future Directions: Further studies to elucidate the different phosphorylation players during sperm capacitation and acrosome reaction (the regulated exocytotic event that releases proteolytic enzymes allowing the spermatozoon to penetrate the zona pellucida and fertilize the oocyte) are essential to understand how the spermatozoon acquires the fertilizing ability to fertilize the oocyte. This knowledge will serve to develop novel diagnostic tools and therapy for male infertility. Antioxid. Redox Signal. 37, 437-450.

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.

From sperm to offspring: Assessing the heritable genetic consequences of paternal smoking and potential public health impacts

Individuals who smoke generally do so with the knowledge of potential consequences to their own health. What is rarely considered are the effects of smoking on their future children. The objective of this work was to review the scientific literature on the effects of paternal smoking on sperm and assess the consequences to offspring. A literature search identified over 200 studies with relevant data in humans and animal models. The available data were reviewed to assess the weight of evidence that tobacco smoke is a human germ cell mutagen and estimate effect sizes. These results were used to model the potential increase in genetic disease burden in offspring caused by paternal smoking, with specific focus on aneuploid syndromes and intellectual disability, and the socioeconomic impacts of such an effect. The review revealed strong evidence that tobacco smoking is associated with impaired male fertility, and increases in DNA damage, aneuploidies, and mutations in sperm. Studies support that these effects are heritable and adversely impact the offspring. Our model estimates that, with even a modest 25% increase in sperm mutation frequency caused by smoke-exposure, for each generation across the global population there will be millions of smoking-induced de novo mutations transmitted from fathers to offspring. Furthermore, paternal smoking is estimated to contribute to 1.3 million extra cases of aneuploid pregnancies per generation. Thus, the available evidence makes a compelling case that tobacco smoke is a human germ cell mutagen with serious public health and socio-economic implications. Increased public education should be encouraged to promote abstinence from smoking, well in advance of reproduction, to minimize the transmission of harmful mutations to the next-generation.

Smoking and Male Infertility: An Evidence-Based Review

Many studies have reported that the contents of cigarette smoke negatively affect sperm parameters, seminal plasma, and various other fertility factors. Nevertheless, the actual effect of smoking on male fertility is not clear. The effect of smoking on semen parameters is based on the well-established biological finding that smoking increases the presence of reactive oxygen species, thereby resulting in oxidative stress (OS). OS has devastating effects on sperm parameters, such as viability and morphology, and impairs sperm function, hence reducing male fertility. However, not all studies have come to the same conclusions. This review sheds light upon the arguable association between smoking and male fertility and also assesses the impact of non-smoking routes of tobacco consumption on male infertility. It also highlights the evidence that links smoking with male infertility, including newly emerging genetic and epigenetic data, and discusses the clinical implications thereof.

Effect of smoking on sperm vitality, DNA integrity, seminal oxidative stress, zinc in fertile men

OBJECTIVE

To assess the effect of smoking on sperm vitality, sperm DNA integrity, semen reactive oxygen species, and zinc levels in fertile men.

METHODS

One-hundred sixty men were investigated. They were divided into 2 equal groups: healthy fertile nonsmokers and healthy fertile smokers. They were subjected to history taking, clinical examination, and semen analysis. In their semen, sperm hypo-osmotic swelling test, sperm DNA fragmentation test, seminal reactive oxygen species, and zinc were assessed.

RESULTS

Compared with fertile nonsmokers, fertile smokers were significantly associated with lower hypo-osmotic swelling test and seminal zinc levels and significantly associated with higher sperm DNA fragmentation percent and seminal reactive oxygen species levels.

CONCLUSION

Smoking (cigarettes/day and duration) has detrimental effects on sperm motility, viability, DNA fragmentation, seminal zinc levels, and semen reactive oxygen species levels, even in fertile men, and it is directly correlated with cigarette quantity and smoking duration.

Cadmium reduces nitric oxide production by impairing phosphorylation of endothelial nitric oxide synthase

Cadmium (Cd) perturbs vascular health and interferes with endothelial function. However, the effects of exposing endothelial cells to low doses of Cd on the production of nitric oxide (NO) are largely unknown. The objective of the present study was to evaluate these effects by using low levels of CdCl2concentrations, ranging from 10 to 1000 nmol/L. Cd perturbations in endothelial function were studied by employing wound-healing and MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assays. The results suggest that a CdCl2concentration of 100 nmol/L maximally attenuated NO production, cellular migration, and energy metabolism in endothelial cells. An egg yolk angiogenesis model was employed to study the effect of Cd exposure on angiogenesis. The results demonstrate that NO supplementation restored Cd-attenuated angiogenesis. Immunofluorescence, Western blot, and immuno-detection studies showed that low levels of Cd inhibit NO production in endothelial cells by blocking eNOS phosphorylation, which is possibly linked to processes involving endothelial function and dysfunction, including angiogenesis.

Indications of the mechanisms involved in improved sperm parameters by zinc therapy

OBJECTIVE

To determine possible indications of the mechanisms involved in improved sperm parameters by zinc therapy in asthenozoospermic men.

SUBJECTS AND METHODS

Forty-five men with asthenozoospermia (>or=40% immotile sperm) were randomized into four therapy groups: zinc only: n = 11; zinc + vitamin E: n = 12 and zinc + vitamins E + C: n = 14 for 3 months, and non-therapy control group: n = 8. Semen analysis was done according to WHO guidelines. Malone dialdehyde, tumour necrosis factor-alpha (TNF-alpha), total antioxidant capacity, superoxide dismutase (SOD) and glutathione peroxidase were determined in the semen and serum. Antisperm antibodies IgG, IgM and IgA were evaluated by immunobeads. Sperm chromatin integrity was determined by acid denaturation by acridine orange and sperm apoptosis by light and electron microscopy. The effect of zinc on in vitro induced sperm oxidative stress by NADH was evaluated.

RESULTS

Asthenozoospermia was significantly associated with oxidative stress with higher seminal malone dialdehyde (8.8 vs. 1.8 mmol/l, p < 0.001) and TNF-alpha (60 vs. 12 pg/l, p < 0.001), and low total antioxidant capacity (1.8 vs. 8.4, p < 0.01), SOD (0.8 vs. 3.1, p < 0.01) and glutathione peroxidase (1.6 vs. 4.2, p < 0.05), compared to normozoospermia. Zinc therapy alone, in combination with vitamin E or with vitamin E + C were associated with comparably improved sperm parameters with less oxidative stress, sperm apoptosis and sperm DNA fragmentation index (DFI). On the whole, there was no difference in the outcome measures between zinc only and zinc with vitamin E and combination of vitamins E + C. In the in vitro experiment zinc supplementation resulted in significantly lower DFI (14-29%, p < 0.05) compared to zinc deficiency.

CONCLUSION

Zinc therapy reduces asthenozoospermia through several mechanisms such as prevention of oxidative stress, apoptosis and sperm DNA fragmentation.

Semen quality and reproductive endocrine function with regard to blood cadmium in Croatian male subjects

In 123 Croatian men with no occupational exposure to metals, the influence of cadmium on reproductive parameters was examined after adjusting for age, smoking, alcohol, and biomarkers of lead, copper, zinc, and selenium. The following variables were measured: blood cadmium (BCd), blood lead (BPb), activity of delta-aminolevulinic acid dehydratase (ALAD), erythrocyte protoporphyrin, serum copper (SCu), serum zinc (SZn), serum selenium (SSe), activity of glutathione peroxidase (GPx) in blood, testis size, semen quality (including sperm concentration, motility, viability, and morphology), indicators in seminal fluid (the lactate dehydrogenase isoenzyme LDH-C4, fructose, zinc, acid phosphatase, and citric acid), and hormones in serum (follicle-stimulating hormone--FSH, luteinizing hormone, prolactin, testosterone, and estradiol). The median and range BCd values were 2.94 (0.49-11.93) microg/L in 61 smokers and 0.59 (0.20-3.71) microg/L in 62 nonsmokers (p < 0.0001). Smoking habits (cigarettes/day) highly significantly correlated with BCd (p < 0.0001). After adjusting for potential confounding variables by multiple regression, BCd was significantly associated with a decrease in testis size (p < 0.03) and an increase in serum estradiol (p < 0.005), FSH (p < 0.03), and testosterone (p < 0.04). Smoking was significantly associated with a decrease in serum prolactin (p < 0.006) and LDH-C4 in seminal fluid (p < 0.03). Several reproductive parameters were significantly associated with BPb and ALAD, biomarkers of lead, and/or with SCu, SZn, SSe, and GPx. The necessity of controlling for various metals, and other potential confounders when assessing the influence of a particular metal on reproductive function in men, is emphasized.

The relationship between serum trace element changes and visual function in heavy smokers

PURPOSE

The aim of this prospective study was to evaluate serum manganese (Mn), zinc (Zn) and copper (Cu) levels and visual functions including visual acuity, colour vision, pattern visual evoked potentials (PVEPs), and contrast sensitivity in heavy smokers and to compare these with the equivalent levels and functions in non-smokers.

METHODS

Data were recorded in 24 healthy, chronic and heavy cigarette smokers and 16 healthy, non-smoking control subjects. Serum Zn, Cu and Mn concentrations in all subjects were measured by atomic absorption spectrophotometry.

RESULTS

Both study and control subjects had normal visual acuity and colour vision. Pattern visual evoked potentials were normal in all study and control subjects. Contrast sensitivity was significantly reduced in heavy smokers compared to non-smokers (p < 0.023), despite the fact that central vision and PVEP responses were not affected. Mean serum Mn and Zn levels were significantly lower in smokers than in non-smokers (p < 0.0001 and p < 0.005, respectively).

CONCLUSIONS

Reduced contrast sensitivity values associated with low levels of serum Mn and Zn, which function as cofactors of superoxide dismutase in erythrocyte and other nucleated cells, suggest a possible role of trace elements in smoking-induced early retinal toxicity.

Lead exposure causes generation of reactive oxygen species and functional impairment in rat sperm

The relationships between blood lead, sperm lead, sperm reactive oxygen species (ROS) level, and sperm fertile capability were investigated to understand the effects of lead exposure on sperm function and the mechanism of these effects. Male Sprague-Dawley rats, 7 weeks old, were randomly divided into control group and lead-treated group. The controls and lead-treated animals received intraperitoneal injection of 10 mg sodium acetate and 10 mg lead acetate/kg body weight, respectively, weekly for 6 or 9 weeks. The blood lead and epididymal sperm lead were analyzed by graphite furnace atomic absorption spectrophotometer. Chemiluminescence was measured to evaluate the generation of sperm ROS. Sperm-oocyte penetration rate (SOPR) was measured to evaluate sperm function. After 6 weeks of lead exposure, the rats had average blood lead levels of 32 microg/dl, sperm lead levels of 0.67 +/- 0.11 microg/10(9) sperm, unchanged epididymal sperm counts, percent of motile sperms, and motile epididymal sperm counts compared with control animals. However, after 9 weeks of lead exposure, the rats had average blood lead levels of 48.0 +/- 4.3 microg/dl, sperm lead levels of 0.88 +/- 0.16 microg/10(9) sperm, statistically lower epididymal sperm counts, and lower motile epididymal sperm counts. There was a good correlation between the blood lead and sperm lead(r2 = 0.946, P < 0.001). The sperms of lead-exposed rats produced significantly higher counts ofchemiluminescence than did those from the control rats (P < 0.001). The chemiluminescence counts were positively associated with sperm lead level (r2 = 0.613, P < 0.001). Epididymal sperm counts, motility and motile epididymal sperm counts were negatively associated with sperm chemiluminescence (r2 = 0.255, 0.152, and 0.299; P < 0.01, 0.05, and 0.01, respectively). The SOPR were positively associated with epididymal sperm counts, motility and motile epididymal sperm counts (r2 = 0.136, 0.285, and 0.264; P < 0.05, 0.01, and 0.001, respectively). The sperm chemiluminescence was negatively associated with SOPR (r2 = 0.519, P < 0.001). It is concluded that lead exposure probably affected the sperm function by activating one of the pathways of ROS generation.