Male-mediated developmental toxicity

Optimizing preconception care and interventions for improved population health

There is growing literature indicating that optimal preconception health is associated with improved reproductive, perinatal, and pediatric outcomes. Given that preconception care is recommended for all individuals planning a pregnancy, medical providers and public health practitioners have a unique opportunity to optimize care and improve health outcomes for reproductive-aged individuals. Knowledge of the determinants of preconception health is important for all types of health professionals, including policy makers. Although some evidence-based recommendations have already been implemented, additional research is needed to identify factors associated with favorable health outcomes and to ensure that effective interventions are made in a timely fashion. Given the largely clinical readership of this journal, this piece is primarily focused on clinical care. However, we acknowledge that optimizing preconception health for the entire population at risk of pregnancy requires broadening our strategies to include population-health interventions that consider the larger social systems, structures, and policies that shape individual health outcomes.

Environmental contaminants, endocrine disruption, and transgender: Can "born that way" in some cases be toxicologically real?

Gender is viewed by many as strictly binary based on a collection of body traits typical of a female or male phenotype, presence of a genotype that includes at least one copy of a Y chromosome, or ability to produce either egg or sperm cells. A growing non-binary view is that these descriptors, while compelling, may nonetheless fail to accurately capture an individual's true gender. The position of the American Psychological Association (APA) agrees with this view and is that transgender people are a defendable and real part of the human population. The considerable diversity of transgender expression then argues against any unitary or simple explanations, however, prenatal hormone levels, genetic influences, and early and later life experiences have been suggested as playing roles in development of transgender identities. The present review considers existing and emerging toxicologic data that may also support an environmental chemical contribution to some transgender identities, and suggest the possibility of a growing nonbinary brain gender continuum in the human population.

Unveiling the nexus between parental exposure to toxicants and heritable spermiotoxicity - Is life history a shield or a shadow?

The knowledge on parental experiences is critical to predict how organisms react to environmental challenges. So, the DNA integrity of Procambarus clarkii spermatozoa exposed ex vivo to the herbicide penoxsulam (Px) or ethyl methanesulfonate (EMS; model genotoxicant) was assessed with and without the influence of in vivo parental exposure to the same agents. The parental exposure alone did not affect the DNA of unexposed spermatozoa. However, the history of Px exposure increased the vulnerability to oxidative lesions in Px-exposed offspring. Otherwise, parental exposure to EMS allowed the development of protection mechanisms expressed when F₁ was also exposed to EMS, unveiling life history as a shield. The parental exposure to a different agent adverse and decisively affected Px spermiotoxic potential, pointing out life history as a shadow to progeny. Given the complexity of the aquatic contamination scenarios, involving mixtures, the spermiotoxicity of Px to wild P. clarkii populations emerged as probable.

The impact of preconceptional exposure of F0 male mice to bisphenol A alone or in combination with X-rays on the intrauterine development of F2 progeny

Bisphenol A (BPA) is used for the production of polycarbonates and epoxy resins. Exposure to chemical and physical environmental factors may influence the health of exposed individuals, and of the next generations. This paper describes the prenatal effects in the F2 generation of mice after exposure of F0 pubescent or mature males to BPA (5 mg/kg bw, 10 mg/kg bw, 20 mg/kg bw), X-rays (0.05 Gy) or a combination of both factors in low doses (0.05 Gy + 5 mg/kg bw BPA) for 8 weeks. F1 males were mated with females from the same group but from a different litter. The females were sacrificed before parturition and examined for the number of implantations, live foetuses, as well as early and late post-implantation deaths. The fertility of males and the percentage of pregnant females in each group were also assessed. Exposure of pubescent F0 males to 10 mg/kg bw of BPA decreased the frequency of fertile males. Following exposure of pubescent males, the frequency of pregnant females decreased in the groups of 10 mg/kg bw and 20 mg/kg bw of BPA, whereas after exposure of adult F0 males in the groups of 5 mg/kg bw and 20 mg/kg bw of BPA, no significant changes in the frequency of total, live and dead implantations in all the experimental groups were found. The results observed in regard to prenatal development of the F2 generation suggest that sperm of the sons of F0 pubescent males exposed to BPA contains genetic defects that affect the possibility of fertilization. The results of both pubescent and mature males exposed to BPA showed that fertilized eggs died before implantation, probably due to defects induced in the sperm. This confirmed that BPA induced transgenerational effects in male germ cells.

In vitro effect of ferrous sulphate on bovine spermatozoa motility parameters, viability and Annexin V-labeled membrane changes

The aim of this study was to assess the dose- and time-dependent in vitro effects of ferrous sulphate (FeSO₄.7H₂O) on the motility parameters, viability, structural and functional activity of bovine spermatozoa. Spermatozoa motility parameters were determined after exposure to concentrations (3.90, 7.80, 15.60, 31.20, 62.50, 125, 250, 500 and 1000 μM) of FeSO₄.7H₂O using the SpermVision^TM CASA (Computer Assisted Semen Analyzer) system in different time periods. Cell viability was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide (MTT) assay, and the Annexin V-Fluos was applied to detect the membrane integrity of spermatozoa. The initial spermatozoa motility showed increased average values at all experimental concentrations compared to the control group (culture medium without FeSO₄.7H₂O). After 2 h, FeSO₄.7H₂O stimulated the overall percentage of spermatozoa motility at the concentrations of ≤ 125 μM. However, experimental administration of 250 μM of FeSO₄.7H₂O significantly (P < 0.001) decreased the spermatozoa motility but had no negative effect on the cell viability (P < 0.05) (Time 2 h). The lowest viability was noted after the addition of ≥ 500 μM of FeSO₄.7H₂O (P < 0.001). The concentrations of ≤ 62.50 μM of FeSO₄.7H₂O markedly stimulated (P < 0.001) spermatozoa activity after 24 h of exposure, while at high concentrations of ≥ 500 μM of FeSO₄.7H₂O the overall percentage of spermatozoa motility was significantly inhibited (P < 0.001) and it elicited cytotoxic action. Fluorescence analysis confirmed that spermatozoa incubated with higher concentrations (≥ 500 μM) of FeSO₄.7H₂O displayed apoptotic changes, as detected in head membrane (acrosomal part) and mitochondrial portion of spermatozoa. Moreover, the highest concentration and the longest time of exposure (1000 μM of FeSO₄.7H₂O; Time 6 h) induced even necrotic alterations to spermatozoa. These results suggest that high concentrations of FeSO₄.7H₂O are able to induce toxic effects on the structure and function of spermatozoa, while low concentrations may have the positive effect on the fertilization potential of spermatozoa.

Reproductive and embryological toxicity of lead acetate in male mice and their offspring and mitigation effects of quercetin

Exposure to heavy metals not only impacts on fertility in males, it may also affect the offspring. The aim of the present study was to examine the toxic effects of lead acetate on fertility in male mice and their offspring, and the potential effect of quercetin on mitigating the likely effects. Experimental mice were randomly divided into three groups and administered with (i) distilled water (control); (ii) lead acetate (150 mg/kg BW/day); (iii) lead acetate (150 mg/kg BW/day) with quercetin (75 mg/kg BW/day). Lead acetate administration in male mice adversely affected their fertility through changes in sperm motility, viability, morphology, maturity, membrane integrity, and intracellular reactive oxygen species (P <  0.05). Similar findings were observed in the offspring of the lead-treated male mice. Early embryonic development and implantation rate were also adversely influenced in both the sires and offspring when male mice were treated with lead acetate (P <  0.05). The data demonstrated that down-regulation of Cks2 (CDC28 protein kinase regulatory subunit-2) in sperm had an association with early embryonic development in lead acetate treated group. In conclusion, lead acetate administration adversely impacted on the fertility of the male mice and their male offspring fertility; on the other hand, paternal quercetin co-administration somewhat ameliorated the adverse effects of lead on male mice and their offspring.

Strawberry fruit (Fragaria x ananassa Romina) juice attenuates oxidative imbalance with concomitant modulation of metabolic indices linked to male infertility in testicular oxidative injury

This study investigated the protective properties of strawberry fruit on testicular oxidative injury. Oxidative injury was induced in vitro in testicular tissue homogenates by incubation with ferrous sulphate (FeSO₄ ) in the presence and absence of strawberry fruit extract (SFE) for 30 min at 37˚C, with gallic acid serving as the standard antioxidant drug. Induction of oxidative injury significantly reduced glutathione, cholesterol and triglyceride levels; and inhibited SOD, catalase and ENTPDase activities when compared to normal control. It also led to exacerbated nitric oxide, malondialdehyde, LDL-cholesterol levels, acetylcholinesterase, ATPase and lipase activities. These effects were, however, reversed following treatment with SFE when compared to the untreated control, except for cholesterol and triglyceride levels. Additionally, the induction of the oxidative injury led to alterations in testicular lipid metabolites that were accompanied by the activation of α-linolenic acid and linoleic acid metabolic pathways. While SFE treatment had no significant impact on the altered metabolites, it repressed pathways for mitochondrial beta-oxidation of long-chain saturated fatty acids and plasmalogen synthesis. High-performance liquid chromatography analysis of SFE revealed the presence of rutin, caffeic acid, p-coumarin and cinnamic acid. These data imply the protective potentials of strawberry fruits against testicular oxidative injury.

Ocimum tenuiflorum mitigates iron-induced testicular toxicity via modulation of redox imbalance, cholinergic and purinergic dysfunctions, and glucose metabolizing enzymes activities

Oxidative stress is a primary culprit in the pathophysiology of infertility conditions in males. This study investigated the effects of Ocimum tenuiflorum on redox imbalance, cholinergic and purinergic dysfunctions and glucose dysmetabolism in oxidative-mediated testicular toxicity using in vitro, ex vivo and in silico models. Induction of oxidative testicular injury was carried out by incubating normal testicular tissue with 0.1 mM FeSO₄ and treated by co-incubating with different concentrations of O. tenuiflorum infusion for 30 min at 37°C. O. tenuiflorum displayed significant ferric reducing power activity while scavenging DPPH and hydroxyl (OH˙) free radicals in vitro. Oxidative testicular injury significantly reduced the glutathione level and superoxide dismutase and catalase activities with concomitant elevation of malondialdehyde and nitric oxide levels and acetylcholinesterase, ATPase, fructose-1,6-bisphosphatase and glycogen phosphorylase (GlyP) activities. Incubation with the infusion significantly reversed these levels and activities. The phytochemical constituent of the infusion was detected by gas chromatography-mass spectroscopy analysis and revealed favourable binding energies when docked with some of the studied proteins. These results suggest O. tenuiflorum exerts a protective effect against Fe²⁺ induced testicular toxicity via mitigation of redox imbalance while modulating metabolic dysfunctions linked to male infertility.

Nutrition, genetic variation and male fertility

Infertility affects nearly 50 million couples worldwide, with 40-50% of cases having a male factor component. It is well established that nutritional status impacts reproductive development, health and function, although the exact mechanisms have not been fully elucidated. Genetic variation that affects nutrient metabolism may impact fertility through nutrigenetic mechanisms. This review summarizes current knowledge on the role of several dietary components (vitamins A, B₁₂, C, D, E, folate, betaine, choline, calcium, iron, caffeine, fiber, sugar, dietary fat, and gluten) in male reproductive health. Evidence of gene-nutrient interactions and their potential effect on fertility is also examined. Understanding the relationship between genetic variation, nutrition and male fertility is key to developing personalized, DNA-based dietary recommendations to enhance the fertility of men who have difficulty conceiving.

Parental IBD and Long-term Health Outcomes in the Offspring

For decades, the research on reproductive consequences in women with inflammatory bowel disease (IBD) has focused on short-term outcomes, including adverse pregnancy outcomes (eg, abruptio placenta, placenta previa, preeclampsia/eclampsia) and adverse birth outcomes (eg, small for gestational age, preterm birth, and congenital malformations). The long-term health outcomes of the children of parents with IBD have been studied to a much lesser extent, and there is a critical research gap in understanding the influence of parental IBD on long-term outcomes. In this review, we propose the reasons for this lack of evidence and highlight the weakest areas of the research on the impact of parental IBD on offspring health. We will focus on health outcomes in children of parents with IBD from an age of 1 year through childhood, adolescence, and adulthood.

Preclinical toxicity and pharmacokinetics of a new orally bioavailable flubendazole formulation and the impact for clinical trials and risk/benefit to patients

BACKGROUND

Flubendazole, originally developed to treat infections with intestinal nematodes, has been shown to be efficacious in animal models of filarial infections. For treatment of filarial nematodes, systemic exposure is needed. For this purpose, an orally bioavailable amorphous solid dispersion (ASD) formulation of flubendazole was developed. As this formulation results in improved systemic absorption, the pharmacokinetic and toxicological profile of the flubendazole ASD formulation have been assessed to ensure human safety before clinical trials could be initiated.

METHODS & FINDINGS

Safety pharmacology, toxicity and genotoxicity studies have been conducted with the flubendazole ASD formulation. In animals, flubendazole has good oral bioavailability from an ASD formulation ranging from 15% in dogs, 27% in rats to more than 100% in jirds. In in vivo toxicity studies with the ASD formulation, high systemic exposure to flubendazole and its main metabolites was reached. Flubendazole, up to high peak plasma concentrations, does not induce Cmax related effects in CNS or cardiovascular system. In repeated dose toxicity studies in rats and dogs, flubendazole-induced changes were observed in haematological, lymphoid and gastrointestinal systems and in testes. In dogs, the liver was an additional target organ. Upon treatment cessation, at least partial recovery was observed for these changes in dogs. In rats, the No Observed Adverse Effect Level (NOAEL) was 5 mg (as base)/kg body weight/day (mg eq./kg/day) in males and 2.5 mg eq./kg/day in females. In dogs, the NOAEL was lower than 20 mg eq./kg/day. Regarding genotoxicity, flubendazole was negative in the Ames test, but positive in the in vivo micronucleus test.

CONCLUSIONS

Based on these results, in combination with previously described genotoxicity and reproductive toxicity data and the outcome of the preclinical efficacy studies, it was concluded that no flubendazole treatment regimen can be selected that would provide efficacy in humans at safe exposure.

Exenatide reduces oxidative stress and cell death in testis in iron overload rat model

Glucagon-like peptide-1 (GLP-1) has been demonstrated to affect the oxidative stress status in several in vitro, in vivo and clinical studies. The aim of the present study was to evaluate the effect of a GLP-1 analogue, exenatide, on oxidative stress parameters and apoptotic markers in testicular cells in an iron overload rat model. To obtain this model, the animals were randomly divided into three groups (n=6/group). Rats in the control group received intraperitoneal injections of saline. Intraperitoneal iron dextran (60 mg/kg/day) was given to Group FE for 5 days a week for 4 weeks. The third group (Group Fe +E) was given subcutaneous injections of 10 µg/kg exenatide in two divided doses for 4 weeks in addition to iron dextran. Testes of all rats were immediately removed for immunohistochemical staining and to measure the malondialdehyde level and superoxide dismutase enzyme activity. A significant reduction was observed in caspase-8 and -3 enzyme staining in testicular stromal and endothelial cells in exenatide injected iron overloaded rats when compared with controls. Oxidative stress markers malondialdehyde levels and superoxide dismutase enzyme activities were also significantly lower in exenatide-injected rats when compared with controls. These findings indicate that exenatide may be protective against the harmful effects of iron accumulation in testis. Further studies are required to evaluate how exenatide reduces oxidative stress and cell death in iron overloaded testis tissue.

Father's environment before conception and asthma risk in his children: a multi-generation analysis of the Respiratory Health In Northern Europe study

Background

Whereas it is generally accepted that maternal environment plays a key role in child health, emerging evidence suggests that paternal environment before conception also impacts child health. We aimed to investigate the association between children's asthma risk and parental smoking and welding exposures prior to conception.

Methods

In a longitudinal, multi-country study, parents of 24 168 offspring aged 2-51 years provided information on their life-course smoking habits, occupational exposure to welding and metal fumes, and offspring's asthma before/after age 10 years and hay fever. Logistic regressions investigated the relevant associations controlled for age, study centre, parental characteristics (age, asthma, education) and clustering by family.

Results

Non-allergic early-onset asthma (asthma without hay fever, present in 5.8%) was more common in the offspring with fathers who smoked before conception {odds ratio [OR] = 1.68 [95% confidence interval (CI) = 1.18-2.41]}, whereas mothers' smoking before conception did not predict offspring asthma. The risk was highest if father started smoking before age 15 years [3.24 (1.67-6.27)], even if he stopped more than 5 years before conception [2.68 (1.17-6.13)]. Fathers' pre-conception welding was independently associated with non-allergic asthma in his offspring [1.80 (1.29-2.50)]. There was no effect if the father started welding or smoking after birth. The associations were consistent across countries.

Conclusions

Environmental exposures in young men appear to influence the respiratory health of their offspring born many years later. Influences during susceptible stages of spermatocyte development might be important and needs further investigation in humans. We hypothesize that protecting young men from harmful exposures may lead to improved respiratory health in future generations.

Prenatal Paternal Selective Serotonin Reuptake Inhibitors Use and Risk of ADHD in Offspring

OBJECTIVES

It has been shown that maternal prenatal exposure to selective serotonin reuptake inhibitors (SSRIs) may be a risk factor for attention-deficit/hyperactivity disorder (ADHD) in offspring. Our goal was to examine whether paternal SSRI use before conception increases the risk of ADHD in offspring.

METHODS

On the basis of Danish national registers, we conducted a cohort study of 781 470 singletons born between 1996 and 2008 with follow-up throughout 2013. The children whose fathers used SSRIs during the last 3 months before conception were identified as the exposed. Cox regression was used to estimate the hazard ratio (HR) of ADHD.

RESULTS

A total of 7216 children (0.92%) were born to fathers who had used SSRIs during the last 3 months before conception. There were 12 520 children diagnosed with ADHD. Compared with unexposed children, the exposed had a 26% increased risk of ADHD (HR = 1.26, 95% confidence interval [CI]: 1.06-1.51) after adjusting for potential confounders. When extending the exposure window to 1 year before conception, paternal use of SSRIs only during the period of 12 to 3 months before conception was associated with the HR of 1.35 (95% CI: 1.10-1.66), whereas paternal use of SSRIs only during the last 3 months before conception was associated with a similarly increased risk of ADHD (adjusted HR = 1.31, 95% CI: 0.95-1.82).

CONCLUSIONS

The mildly increased risk of ADHD in offspring associated with paternal SSRI use before conception could probably be due to the underlying indications related to SSRI use.

Risk of Neurodevelopmental Disease by Paternal Aging: A Possible Influence of Epigenetic Alteration in Sperm

Sincethe theory of DOHaD has been thrown in the spotlight, most attention has focused on environmental effects of the uterus on developing embryos/fetuses. However, the ontogenesis traces back to gametogenesis. Compared to oogenesis, spermatogenesis goes through far more cell divisions and is therefore more prone to genetic variation and epigenetic alterations. This article will mainly discuss recent findings about the effects of the advanced paternal age on the next generation, in relation to the onset of psychiatric disorders such as autism spectrum disorder. We would like to advocate for further exploration on the DOHaD theory in a wider view.

Ambient and Dosed Exposure to Quaternary Ammonium Disinfectants Causes Neural Tube Defects in Rodents

Background

Quaternary ammonium compounds are a large class of chemicals used for their antimicrobial and antistatic properties. Two common quaternary ammonium compounds, alkyldimethylbenzyl ammonium chloride (ADBAC) and didecyldimethyl ammonium chloride (DDAC), are combined in common cleaners and disinfectants. Introduction of a cleaner containing ADBAC+DDAC in the vivarium caused neural tube defects (NTDs) in mice and rats.

Methods

To further evaluate this finding, male and female mice were dosed in the feed at 60 or 120 mg/kg/day, or by oral gavage at 7.5, 15, or 30 mg/kg ADBAC+DDAC. Mice also received ambient exposure to ADBAC+DDAC from the disinfectant used in the mouse room. Embryos were evaluated on gestational day 10 for NTDs, and fetuses were evaluated on gestational day 18 for gross and skeletal malformations.

Results

We found increased NTDs with exposure to ADBAC+DDAC in both rats and mice. The NTDs persisted for two generations after cessation of exposure. Notably, male exposure alone was sufficient to cause NTDs. Equally significant, ambient exposure from disinfectant use in the vivarium, influenced the levels of NTDs to a greater extent than oral dosing. No gross or significant axial skeletal malformations were observed in late gestation fetuses. Placental abnormalities and late gestation fetal deaths were increased at 120 mg/kg/day, which might explain the lack of malformations observed in late gestation fetuses.

Conclusion

These results demonstrate that ADBAC+DDAC in combination are teratogenic to rodents. Given the increased use of these disinfectants, further evaluation of their safety in humans and their contribution to health and disease is essential.

Fathers Matter: Why It's Time to Consider the Impact of Paternal Environmental Exposures on Children's Health

PURPOSE

Despite accumulating evidence from experimental animal studies showing that paternal environmental exposures induce genetic and epigenetic alterations in sperm which in turn increase the risk of adverse health outcomes in offspring, there is limited epidemiological data on the effects of human paternal preconception exposures on children's health. We summarize animal and human studies showing that paternal preconception environmental exposures influence offspring health. We discuss specific approaches and designs for human studies to investigate the health effects of paternal preconception exposures, the specific challenges these studies may face, and how we might address them.

RECENT FINDINGS

In animal studies, paternal preconception diet, stress, and chemical exposures have been associated with offspring health and these effects are mediated by epigenetic modifications transmitted through sperm DNA, histones, and RNA. Most epidemiological studies have examined paternal preconception occupational exposures and their effect on the risk of birth defects and childhood cancer; few have examined the effects of low-level general population exposure to environmental toxicants. While the design and execution of epidemiological studies of paternal preconception exposures face challenges, particularly with regard to selection bias and recruitment, we believe these are tractable and that preconception studies are feasible.

SUMMARY

New or augmented prospective cohort studies would be the optimal method to address the critical knowledge gaps on the effect of paternal preconception exposures on prevalent childhood health outcomes. Determining if this period of life represents a window of heightened vulnerability would improve our understanding of modifiable risk factors for children's health and wellbeing.

Levels and trends of contaminants in humans of the Arctic

The Arctic Monitoring and Assessment Programme (AMAP) is one of the six working groups established under the Arctic Council. AMAP is tasked with monitoring the levels of contaminants present in the Arctic environment and people as well as assessing their effects on a continuous basis, and reporting these results regularly. Most of the presented data have been collected over the last 20 years and are from all eight Arctic countries. Levels of contaminants appear to be declining in some of the monitored Arctic populations, but it is not consistent across the Arctic. Most Arctic populations continue to experience elevated levels of these contaminants compared to other populations monitored globally. There are certain contaminants, such as perfluorinated compounds and polybrominated diphenyl ethers, which are still increasing in Arctic populations. These contaminants require more investigation to find out the predominant and important sources of exposure, and whether they are being transported to the Arctic through long-range transport in the environment.

Induction of Chronic Inflammation and Altered Levels of DNA Hydroxymethylation in Somatic and Germinal Tissues of CBA/CaJ Mice Exposed to (48)Ti Ions

Although the lung is one of the target organs at risk for cancer induction from exposure to heavy ions found in space, information is insufficient on cellular/molecular responses linked to increased cancer risk. Knowledge of such events may aid in the development of new preventive measures. Furthermore, although it is known that germinal cells are sensitive to X- or γ-rays, there is little information on the effects of heavy ions on germinal cells. Our goal was to investigate in vivo effects of 1 GeV/n (48)Ti ions (one of the important heavy ions found in the space environment) on somatic (lung) and germinal (testis) tissues collected at various times after a whole body irradiation of CBA/CaJ mice (0, 0.1, 0.25, or 0.5 Gy, delivered at 1 cGy/min). We hypothesized that (48)Ti-ion-exposure induced damage in both tissues. Lung tissue was collected from each mouse from each treatment group at 1 week, 1 month, and 6 months postirradiation. For the testis, we collected samples at 6 months postirradiation. Hence, only late-occurring effects of (48)Ti ions in the testis were studied. There were five mice per treatment group at each harvest time. We investigated inflammatory responses after exposure to (48)Ti ions by measuring the levels of activated nuclear factor kappa B and selected pro-inflammatory cytokines in both tissues of the same mouse. These measurements were coupled with the quantitation of the levels of global 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC). Our data clearly showed the induction of chronic inflammation in both tissues of exposed mice. A dose-dependent reduction in global 5hmC was found in the lung at all time-points and in testes collected at 6 months postirradiation. In contrast, significant increases in global 5mC were found only in lung and testes collected at 6 months postirradiation from mice exposed to 0.5 Gy of 1 GeV/n (48)Ti ions. Overall, our data showed that (48)Ti ions may create health risks in both lung and testicular tissues.

Does Ataxia Telangiectasia Mutated (ATM) protect testicular and germ cell DNA integrity by regulating the redox status?

A balanced redox homeostasis in the testis is essential for genetic integrity of sperm. Reactive oxygen species can disturb this balance by oxidation of glutathione, which is regenerated using NADPH, formed by glucose-6-phosphate dehydrogenase (G6PDH). G6PDH is regulated by the Ataxia Telangiectasia Mutated (Atm) protein. Therefore, we studied the redox status and DNA damage in testes and sperm of mice that carried a deletion in Atm. The redox status in heterozygote mice, reflected by glutathione levels and antioxidant capacity, was lower than in wild type mice, and in homozygotes the redox status was even lower. The redox status correlated with oxidative DNA damage that was highest in mice that carried Atm deletions. Surprisingly, G6PDH activity was highest in homozygotes carrying the deletion. These data indicate that defective Atm reduces the redox homeostasis of the testis and genetic integrity of sperm by regulating glutathione levels independently from G6PDH activity.

Iron and copper in male reproduction: a double-edged sword

Iron and copper are essential trace nutrients playing important roles in general health and fertility. However, both elements are highly toxic when accumulating in large quantities. Their direct or indirect impact on the structure and function of male gonads and gametes is not completely understood yet. Excess or deficiency of either element may lead to defective spermatogenesis, reduced libido, and oxidative damage to the testicular tissue and spermatozoa, ultimately leading to fertility impairment. This review will detail the complex information currently available on the dual roles iron and copper play in male reproduction.