Endocrine effects of lifelong exposure to low-dose depleted uranium on testicular functions in adult rat

A deeper understanding about the role of uranium toxicity in neurodegeneration

Natural deposits and human-caused releases of uranium have led to its contamination in the nature. Toxic environmental contaminants such as uranium that harm cerebral processes specifically target the brain. Numerous experimental researches have shown that occupational and environmental uranium exposure can result in a wide range of health issues. According to the recent experimental research, uranium can enter the brain after exposure and cause neurobehavioral problems such as elevated motion related activity, disruption of the sleep-wake cycle, poor memory, and elevated anxiety. However, the exact mechanism behind the factor for neurotoxicity by uranium is still uncertain. This review primarily aims on a brief overview of uranium, its route of exposure to the central nervous system, and the likely mechanism of uranium in neurological diseases including oxidative stress, epigenetic modification, and neuronal inflammation has been described, which could present the probable state-of-the-art status of uranium in neurotoxicity. Finally, we offer some preventative strategies to workers who are exposed to uranium at work. In closing, this study highlights the knowledge of uranium's health dangers and underlying toxicological mechanisms is still in its infancy, and there is still more to learn about many contentious discoveries.

Multigenerational Exposure to Uranium Changes Sperm Metabolome in Rats

Male infertility is a major public health issue that can be induced by a host of lifestyle risk factors such as environment, nutrition, smoking, stress, and endocrine disruptors. Regarding the human population exposed to uranium, it is necessary to explore these effects on male reproduction in multigenerational studies. The sensitivity of mass spectrometry (MS)-based methods has already proved to be extremely useful in metabolite identification in rats exposed to low doses of uranium, but also in human sperm. We applied this method to rat sperm over three generations (F0, F1 and F2) with multigenerational uranium exposure. Our results show a significant content of uranium in generation F0, and a reduction in the pregnancy rate only in generation F1. Based on principal component analysis (PCA), we observed discriminant profiles between generations. The partial least squares discriminant analysis (PLS-DA) of the 48 annotated variables confirmed that parental exposure of generation F0 (during both the preconceptional and prenatal periods) can have metabolic effects on spermatozoa for the next two generations. Metabolomics applied to epididymal spermatozoa is a novel approach to detecting the multigenerational effects of uranium in an experimental model, but could be also recommended to identify potential biomarkers evaluating the impact of uranium on sperm in exposed infertile men.

A critical review of uranium contamination in groundwater: Treatment and sludge disposal

Dissolved uranium in groundwater at high concentrations is an emerging global threat to human and ecological health due to its radioactivity and chemical toxicity. Uranium can enter groundwater by geochemical reactions, natural deposition from minerals, mining, uranium ore processing, and spent fuel disposal. Although much progress has been made in uranium remediation in recent years, most published reviews on uranium treatment have focused on specific methods, particularly adsorption. This article systematically reviews the major treatment technologies, explains their mechanism and progress of uranium removal, and compares their performance under various environmental conditions. Of all treatment methods, adsorption has received much attention due to its ease of use and adaptability under various conditions. However, salinity and competition from other ions limit its application in actual field conditions. Biosorption and bioremediation are also promising methods due to their low-cost and chemical-free operation. Strong base anion exchange resins are more effective at typical groundwater pH conditions. Advanced oxidation processes like photocatalysis produce less sludge and are effective even at low uranium concentrations. Electrocoagulation shows significantly improved performance when organic ligands are added prior to treatment. The significant advantages of membrane filtration are high removal efficiency and the ability to recover uranium. While each technology has its merits and demerits, no single technology is entirely suitable under all conditions. One major area of concern with all technologies is the need to dispose of liquid and solid waste generated after treatment safely. Future research must focus on developing hybrid and state-of-the-art technologies for effective and sustainable uranium removal from groundwater. Developing holistic management strategies for uranium removal will hinge on understanding its speciation, mechanisms of fate and transport, and socio-economic conditions of the affected areas.

Environmental and health hazards of military metal pollution

An increasing body of literature has demonstrated that armed conflicts and military activity may contribute to environmental pollution with metals, although the existing data are inconsistent. Therefore, in this paper, we discuss potential sources of military-related metal emissions, environmental metal contamination, as well as routes of metal exposure and their health hazards in relation to military activities. Emission of metals into the environment upon military activity occurs from weapon residues containing high levels of particles containing lead (Pb; leaded ammunition), copper (Cu; unleaded), and depleted uranium (DU). As a consequence, military activity results in soil contamination with Pb and Cu, as well as other metals including Cd, Sb, Cr, Ni, Zn, with subsequent metal translocation to water, thus increasing the risk of human exposure. Biomonitoring studies have demonstrated increased accumulation of metals in plants, invertebrates, and vertebrate species (fish, birds, mammals). Correspondingly, military activity is associated with human metal exposure that results from inhalation or ingestion of released particles, as well as injuries with subsequent metal release from embedded fragments. It is also notable that local metal accumulation following military injury may occur even without detectable fragments. Nonetheless, data on health effects of military-related metal exposures have yet to be systematized. The existing data demonstrate adverse neurological, cardiovascular, and reproductive outcomes in exposed military personnel. Moreover, military-related metal exposures also result in adverse neurodevelopmental outcome in children living within adulterated territories. Experimental in vivo and in vitro studies also demonstrated toxic effects of specific metals as well as widely used metal alloys, although laboratory data report much wider spectrum of adverse effects as compared to epidemiological studies. Therefore, further epidemiological, biomonitoring and laboratory studies are required to better characterize military-related metal exposures and their underlying mechanisms of their adverse toxic effects.

Low-dose radiation-induced demethylation of 3β-HSD participated in the regulation of testosterone content

The effects of low-dose radiation (LDR, ≤0.1 Gy) on living organisms have been the hot areas of radiation biology but do not reach a definitive conclusion yet. So far, few studies have adequately accounted for the male reproductive system responses to LDR, particularly the regulation of testosterone content. Hence, this study was designed to evaluate the effects of LDR on Leydig cells and testicular tissue, especially the ability to synthesize testosterone. We found that less than 0.2-Gy ⁶⁰ Co gamma rays did not cause significant changes in the hemogram index and the body weight; also, pathological examination did not find obvious structural alterations in testis, epididymis, and other radiation-sensitive organs. Consistently, the results from in vitro showed that only more than 0.5-Gy gamma rays could induce remarkable DNA damage, cycle arrest, and apoptosis. Notably, LDR disturbed the contents of testosterone in mice serums and culture supernatants of TM3 cells and dose dependently increased the expression of 3β-HSD. After cotreatment with trilostane (Tril), the inhibitor of 3β-HSD, increased testosterone could be partially reversed. Besides, DNA damage repair-related enzymes, including DNMT1, DNMT3B, and Sirt1, were increased in irradiated TM3 cells, accompanying by evident demethylation in the gene body of 3β-HSD. In conclusion, our results strongly suggest that LDR could induce obvious perturbation in the synthesis of testosterone without causing organic damage, during which DNA demethylation modification of 3β-HSD might play a crucial role and would be a potential target to prevent LDR-induced male reproductive damage.

Paternal Exposure to Non-essential Heavy Metal Affects Embryo Cleavage and Implantation in Intracytoplasmic Sperm Injection (ICSI) Cycles: Evidence for a Paradoxical Effect

Although the adverse effects of non-essential heavy metals on semen quality have been demonstrated in experimental animal models and occupational human exposure studies, little is known about the reproductive efficiency of exposed sperm during the process of intracytoplasmic sperm injection (ICSI). Our study aims to evaluate the effect of paternal exposure to non-essential heavy metals on embryo efficiency outcomes (embryo cleavage, fragmentation, implantation, and live birth) in ICSI cycle. Ninety-five heterosexual couples who underwent 95 ICSI cycles and 78 fresh embryo transfers between January 2003 and December 2009 were evaluated. Men whose female partner was undergoing ICSI were asked to provide semen and blood samples. Heavy metal levels (Pb, Cd, As, Hg, Ba, and U) were analyzed using an ion-coupled plasma-mass spectrometry (ICP-MS; Agilent 7500 ce, Agilent Technologies, Germany) equipped with a cell dynamic range (CDR). Paternal exposure to trace heavy metals was found to influence intermediate reproductive endpoints in ICSI cycles. After adjusting for paternal and maternal confounders, paternal blood concentrations of Cd [-0.30(-0.11,-0.02)], As [-0.26(-0.16,-0.11)], and U [-0.22(-0.24,-0.02)] were inversely associated with embryo cell cleavage on day 3. Counterintuitively, paternal blood and semen Pb levels [0.26(0.01,0.22); 0.25(0.03,0.14)] as well as semen U levels [0.27(0.01,0.19)] were positively associated with the proportion of implanted embryos. There were no significant associations observed for clinical pregnancy and live birth rates with any paternal heavy metal concentrations in semen and blood. These findings highlight the importance of paternal health for embryo efficiency outcomes in ICSI treatment cycles and the need for more male partner inclusive counseling in fertility practice. They also underline a paradoxical positive association between some heavy metal pollutants at low exposure levels and reproductive outcomes.

Waterborne uranium causes toxic effect and thyroid disruption in zebrafish larvae

Uranium is a radioactive element that is widely present in aquatic environment. However, limited knowledge is available about the effect of uranium on thyroid system, which plays a key role in the development of animals. In this study, zebrafish embryos were exposed to different environmentally relevant concentrations of uranium (2, 20 and 100 μg/L) for 120 h. The bioaccumulation, developmental toxicities, changes of thyroid hormones (THs) and key genes related to the hypothalamic-pituitary-thyroid (HPT) axis in larvae were analyzed after exposure. Results showed that uranium could bioaccumulate in zebrafish larvae, with the bioconcentration factors ranging from 49.6 to 523. Consequently, significant developmental toxicities and changes in locomotor activities were observed with a concentration-dependent manner. The levels of triiodothyronine (T3) levels in larvae were substantially decreased, whereas those of thyroxine (T4) were increased in fish bodies. The levels of THs were regulated by the negative feedback loops through HPT axis related genes, most of which (NIS, Deio1, Deio2, TRα, TSHβ and UGT1ab) were significantly depressed after exposure to uranium. Our results suggest the potential toxicities and thyroid disruption of uranium on zebrafish, which would provide baseline data set for better understanding the impact of waterborne uranium on aquatic organisms and the associated mechanisms. This study also highlights the key role of thyroid disruption in the ecological risk assessment of uranium pollution.

Chronic oral depleted uranium leads to reproductive damage in male rats through the ROS-hnRNP A2/B1-COX-2 signaling pathway

Depleted uranium (DU) is widely used in civil and military activities. The testis is one of the target organs of DU chronic toxicity. In this study, male SD rats were chronically exposed to DU by 3, 30, 300 mg U/kg through oral intake. After 6 months and 12 months of exposure, it was found that DU could lead to increased oxidative stress levels, decreased glutathione S-transferases (GSTs) expression, resulting in testicular injury and decreased serum testosterone (T) level in rats. Heterogeneous nuclear ribonucleoprotein A2/B1 (hnRNP A2/B1) expression increases with the increase of DU exposure dose. After upregulation of hnRNP A2/B1 expression, the GC-1 cell injury caused by DU is aggravated, suggesting that hnRNP A2/B1 may play an important role in the reproductive toxicity of DU. At the same time, 12 months after chronic oral exposure to DU, the expression level of cyclooxygenase-2 (COX-2) and proinflammatory factor prostaglandin E2 (PGE2) in testicular tissue were increased, and the level of hnRNP A2/B1 caused by DU was decreased by reactive oxygen scavenger N-acetylcysteine (NAC). As hnRNP A2/B1 is a COX-2 regulator, DU may lead to the upregulation of hnRNP A2/B1 expression through the increase of oxidative stress level in germ cells, which in turn leads to the increase of COX-2 and PGE2 level, and ultimately result in the reproductive toxicity. In this study, the regulation mechanism of the ROS-hnRNP A2/B1-COX-2 pathway on DU-induced reproductive damage in male rats was hypothesized, providing a new target for the prevention and treatment of chronic poisoning of DU.

Emerging health risks and underlying toxicological mechanisms of uranium contamination: Lessons from the past two decades

Uranium contamination is a global health concern. Regarding natural or anthropogenic uranium contamination, the major sources of concern are groundwater, mining, phosphate fertilizers, nuclear facilities, and military activities. Many epidemiological and laboratory studies have demonstrated that environmental and occupational uranium exposure can induce multifarious health problems. Uranium exposure may cause health risks because of its chemotoxicity and radiotoxicity in natural or anthropogenic scenarios: the former is generally thought to play a more significant role with regard to the natural uranium exposure, and the latter is more relevant to enriched uranium exposure. The understanding of the health risks and underlying toxicological mechanisms of uranium remains at a preliminary stage, and many controversial findings require further research. In order to present state-of-the-art status in this field, this review will primarily focus on the chemotoxicity of uranium, rather than its radiotoxicity, as well as the involved toxicological mechanisms. First, the natural or anthropogenic uranium contamination scenarios will be briefly summarized. Second, the health risks upon natural uranium exposure, for example, nephrotoxicity, bone toxicity, reproductive toxicity, hepatotoxicity, neurotoxicity, and pulmonary toxicity, will be discussed based on the reported epidemiological cases and laboratory studies. Third, the recent advances regarding the toxicological mechanisms of uranium-induced chemotoxicity will be highlighted, including oxidative stress, genetic damage, protein impairment, inflammation, and metabolic disorder. Finally, the gaps and challenges in the knowledge of uranium-induced chemotoxicity and underlying mechanisms will be discussed.

A review of biological effects and treatments of inhaled depleted uranium aerosol

Depleted uranium (DU) is primarily used for DU bombs and DU tanks in the military. Aerosol inhalation is considered the primary route of DU exposure. Although laboratory tests have confirmed that inhalation of DU aerosol can cause lung, kidney, and other organ damage, epidemiological studies have found no conclusive evidence that persons in areas with prolonged exposure to DU-containing bombs are affected. After the body inhaled DU aerosols, we first clear the insoluble DU through whole-lung lavage (WLL). Then we eliminate the soluble uranium by the chelating agent. Besides, reducing DU damage to tissues and cells through drugs is also an important treatment method. In future research, emphasis should be placed on the damage mechanism of DU aerosol, the laboratory and clinical research of DU chelating agents, the research on the combination of DU chelating agent and WLL, and the research and development of new drugs to prevent DU damage.

A Review of Uranium-Induced Reproductive Toxicity

As a heavy metal nuclear fuel, uranium is used in various civil and military projects, resulting in environmental pollution. Uranium can enter the body through the mouth, nose and skin, threatening human health. The reproductive organs are sensitive to uranium. For certain exposure times, doses and modes, uranium can produce toxic effects on the reproductive organs. The reproductive toxicity of uranium can be produced through different mechanisms of action, such as changing the level of sex hormones in the body, disrupting the expression of genes or proteins related to reproduction and causing oxidative stress and inflammation. Uranium thus can cause toxic effects to the reproductive system, leading to histopathological changes and decreased conception rates, and may damage the health of the body. This paper reviews the research progress on uranium reproductive toxicity in recent years and indicates a direction for future research on uranium reproductive toxicity and its mechanisms.

Association of adverse birth outcomes with prenatal uranium exposure: A population-based cohort study

Uranium (U) is a well-recognized hazardous heavy metal with embryotoxicity and fetotoxicity. However, little is known about its association with adverse birth outcomes. We aimed to investigate the potential correlation between prenatal U exposure and birth outcomes. Urine samples of 8500 women were collected before delivery from a birth cohort in Wuhan, China. Concentrations of urinary U and other metals were measured by inductively coupled plasma mass spectrometry. We used multivariable logistic regressions to evaluate the associations between urinary U concentrations and adverse birth outcomes, such as preterm birth (PTB), low birth weight (LBW) and small for gestational age (SGA). Associations of urinary U concentrations with gestational age, birth weight, and birth length were investigated by linear regressions. The geometric mean of U concentration was 0.03 μg/L. After adjustment for potential confounders, we found each Log₂-unit increase in U concentration was associated with a significant decrease in gestational age [adjusted β = -0.32 day; 95% confidence interval (CI): -0.44, -0.20] and a significant increased likelihood of PTB (adjusted OR = 1.18, 95% CI: 1.07, 1.29). This birth cohort uncovered an association of maternal exposure to U during pregnancy with decreased gestational age and increased risk of PTB. Our findings reveal an association of maternal exposure to U during pregnancy with decreased gestational age and increased risk of PTB.

Coenzyme Q10 mitigates ionizing radiation-induced testicular damage in rats through inhibition of oxidative stress and mitochondria-mediated apoptotic cell death

Radiotherapy is a common treatment modality for cancer patients; however, its use is limited by decreasing the probability of fertility in male cancer survivors. Therefore, this study aimed to define the capability of coenzyme Q10 (CoQ10), a potent stimulator of mitochondrial function, in attenuating ionizing radiation (IR)-induced spermatogenesis impairments. Male Sprague Dawley rats were exposed to a single dose of ϒ-rays (10 Gy) and/or treated with CoQ10 (10 mg/kg, orally, for 2 consecutive weeks). IR mediated irregular seminiferous tubules, which were emerged with typical morphological characteristics of apoptosis, and nuclear condensation, while CoQ10 significantly preserved the testicular structure and maintained spermatogenesis, which was displayed by higher levels of serum estradiol and testosterone. CoQ10 remarkably augmented sperm count, motility, and viability while diminished the rate of sperm-defects relatively to their counterparts after IR exposure. CoQ10 modulations in reproductive parameters were underpinned by attenuating IR-induced oxidative stress as evidenced by decreasing lipid peroxidation and increasing the antioxidant enzymes glutathione peroxidase and glutathione-s-transferase activities, and glutathione level. Supporting the involvement of CoQ10 in the anti-apoptotic response, the reduced mRNA expression levels of p53, Puma, and Bax accompanied by the increased Bcl-2 mRNA expression were observed. Subsequently, CoQ10 ameliorated the mitochondria dependent apoptotic pathway through diminishing Bax/Bcl-2 ratio, caspase-3 protein expression, and DNA fragmentation in testes of irradiated rats. Taken together, our findings showed that CoQ10 conserved against IR-induced steroidogenesis disruption through subsiding mitochondria-mediated oxidative stress injury in germinal cells.

Multigenerational exposure to uranium changes morphometric parameters and global DNA methylation in rat sperm

There is increasing evidence that environmental exposures early in fetal development influence phenotype and give rise to disease risk in the next generations. We previously found that lifelong exposure to uranium, an environmental contaminant, induced subtle testicular and hormonal defects; however, its impact on the reproductive system of multiple subsequent generations was unexplored. Herein, rats were exposed to a supra-environmental and non-nephrotoxic concentration of natural uranium (U, 40 mg·L^-1 of drinking water) from postnatal life to adulthood (F0), during fetal life (F1), and only as the germ cells from the F1 generation (F2). General parameters (reproductive indices, epididymal weight) and sperm morphology were assessed in the three generations. In order to identify the epigenetic effects of U, we analyzed also the global DNA methylation profile and described for the first time the mRNA expression levels of markers involved in the (de)methylation system in rat epididymal spermatozoa. Our results showed that the F1 generation had a reduced pregnancy rate. Despite the sperm number being unmodified, sperm morphology was affected in the F0, F1 and F2 generations. Morphometric analysis for ten parameters was detailed for each generation. No common parameter was detected between the three generations, but the head and the middle-piece were always modified in the abnormal sperms. In the F1 U-exposed generation, the total number of abnormal sperm was significantly higher than in the F0 and F2 generations, suggesting that fetal exposure to uranium was more deleterious. This effect could be associated with the pregnancy rate to produce the F2 generation. Interestingly, global DNA methylation analysis showed also hypomethylation in the sperm DNA of the last F2 generation. In conclusion, our study demonstrates that uranium can induce morphological sperm defects and changes in the DNA methylation level after multigenerational exposure. The epigenetic transgenerational inheritance of U-induced reproductive defects should be assessed in further experiments.

Effects of Radiation on Drug Metabolism: A Review

BACKGROUND

Radiation is the fourth most prevalent type of pollution following the water, air and noise pollution. It can adversely affect normal bodily functions. Radiation alters the protein and mRNA expression of drugmetabolizing enzymes and drug transporters and the pharmacokinetic characteristics of drugs, thereby affecting drug absorption, distribution, metabolism, and excretion. Therefore, it is important to study the pharmacokinetic changes in drugs under radiation.

METHODS

To update data on the effects of ionizing radiation and non-ionizing radiation caused by environmental pollution or clinical treatments on the protein and mRNA expression of drug-metabolizing enzymes and drug transporters. Data and information on pharmacokinetic changes in drugs under radiation were analyzed and summarized.

RESULTS

The effect of radiation on cytochrome P450 is still a subject of debate. The widespread belief is that higherdose radiation increased the expression of CYP1A1 and CYP1B1 of rat, zebrafish or human, CYP1A2, CYP2B1, and CYP3A1 of rat, and CYP2E1 of mouse or rat, and decreased that of rat's CYP2C11 and CYP2D1. Radiation increased the expression of multidrug resistance protein, multidrug resistance-associated protein, and breast cancer resistance protein. The metabolism of some drugs, as well as the clearance, increased during concurrent chemoradiation therapy, whereas the half-life, mean residence time, and area under the curve decreased. Changes in the expression of cytochrome P450 and drug transporters were consistent with the changes in the pharmacokinetics of some drugs under radiation.

CONCLUSION

The findings of this review indicated that radiation caused by environmental pollution or clinical treatments can alter the pharmacokinetic characteristics of drugs. Thus, the pharmacokinetics of drugs should be rechecked and the optimal dose should be re-evaluated after radiation.

Surveillance results and bone effects in the Gulf War depleted uranium-exposed cohort

A small group of Gulf War I veterans wounded in depleted uranium (DU) friendly-fire incidents have been monitored in a clinical surveillance program since 1993. During the spring of 2017, 42 members of the cohort were evaluated with a protocol which includes exposure monitoring for total and isotopic uranium concentrations in urine and a comprehensive assessment of health outcomes including measures of bone metabolism, and for participants >50 years, bone mineral density (BMD) determination. Elevated urine U concentrations were observed in cohort members with retained DU shrapnel fragments. Only the mean serum estradiol concentration, a marker of bone metabolism, was found to be significantly different for lower-vs- higher urine U (uU) cohort sub-groups. For the first time, a significant deficit in BMD was observed in the over age 50, high uU sub-group. After more than 25 years since first exposure to DU, an aging cohort of military veterans continues to exhibit few U-related adverse health effects in known target organs of U toxicity. The new finding of reduced BMD in older cohort members, while biologically plausible, was not suggested by other measures of bone metabolism in the full (all ages) cohort, as these were predominantly within normal limits over time. Only estradiol was recently found to display a difference as a function of uU grouping. As BMD is further impacted by aging and the U-burden from fragment absorption accrues in this cohort, a U effect may be clarified in future surveillance visits.

Transcriptomic and methylomic analysis reveal the toxicological effect of 2,3,7,8-Tetrachlorodibenzodioxin on human embryonic stem cell

Cumulating epidemiological studies demonstrated that environmental exposure to endocrine disrupting chemicals (EDCs) during the early stages of fetal development is associated with the increase in disease susceptibility in later life. The fetal developmental plasticity is considered as a protective mechanism against an undesirable prenatal environment. Dioxin is one of the environmental contaminants and is considered a diabetogenic factor. Experimental animal and human epidemiological studies have revealed that dioxin exposure was associated with insulin resistance and altered beta cell function. But the effect of dioxin exposure in early stage of fetal development is still largely unknown. In this report, we used the human embryonic stem cell (hESC) line, VAL-3, as a model, together with Methyl-CpG Binding Domain (MBD) protein-enriched genome sequencing and transcriptome sequencing (RNA-seq), in order to determine the dynamic changes of the epigenetic landscape and transcriptional dysregulation in hESC upon dioxin exposure. The bioinformatics analyses including the Database for Annotation, Visualization and Integrated Discovery (DAVID) analysis and Ingenuity Pathway Analysis (IPA) highlighted the predisposed neural, hepatic, cardiac and metabolic toxicological effects of dioxin during the fetal development.

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.

DNA methylation and potential multigenerational epigenetic effects linked to uranium chronic low-dose exposure in gonads of males and females rats

INTRODUCTION

An increased health problem in industrialised countries is the contemporary concern of public and scientific community as well. This has been attributed in part to accumulated environmental pollutants especially radioactive substances and the use of nuclear power plants worldwide. However, the outcome of chronic exposure to low doses of a radionuclide such as uranium remains unknown. Recently, a paradigm shift in the perception of risk of radiotoxicology has emerged through investigating the possibility of transmission of biological effects over generations, in particular by epigenetic pathways. These processes are known for their crucial roles associated with the development of several diseases.

OBJECTIVE

The current work investigates the epigenetic effect of chronic exposure to low doses of uranium and its inheritance across generations. Materials and Methods To test this proposition, a rodent multigenerational model, males and females, were exposed to a non-toxic concentration of uranium (40mgL^-1 drinking water) for nine months. The uranium effects on were evaluated over three generations (F0, F1 and F2) by analysing the DNA methylation profile and DNMT genes expression in ovaries and testes tissues.

RESULTS

Here we report a significant hypermethylation of testes DNA (p <0.005) whereas ovaries showed hypomethylated DNA (p <0.005). Interestingly, this DNA methylation profile was significantly maintained across generations F0, F1 and F2. Furthermore, qPCR results of both tissues imply a significant change in the expression of DNA methyltransferase genes (DNMT 1 and DNMT3a/b) as well.

CONCLUSION

Altogether, our work demonstrates for the first time a sex-dependance and inheritance of epigenetic marks, DNA methylation, as a biological response to the exposure to low doses of uranium. However, it is not clear which type of reproductive cell type is more responsive in this context.