Intrauterine life represents a sensitive period during which low‑dose radiation may shape long‑term health outcomes; however, its impact, particularly when combined with lifelong metabolic stressors such as a high‑fat diet (HFD) remains unclear. This study investigated whether prenatal exposure to low‑dose cesium‑137 influences hepatic outcomes in offspring. Pregnant C57BL/6 J mice received cesium‑137 in drinking water throughout gestation (total dose: ∼100 mGy). After weaning, offspring were fed either a standard diet (SD) or HFD. Body and liver weights, plasma biochemistry, and tissue analyses were performed at 10 weeks and 15 months of age. Prenatal low‑dose irradiation (LDI) did not show major effects in offspring subjected to SD; however, it exacerbates HFD-induced adverse effects. A sex‑ and age‑dependent interaction with HFD emerged: At 15 months of age, irradiated males subjected to HFD showed a 2.8-fold increase in hepatic tumor incidence, accompanied by a significant elevation of ALT and AST levels, pronounced dyslipidemia (cholesterol and triglycerides), and a 2.5-fold upregulation of Myc proto-oncogene. These findings may represent the first evidence that intrauterine LDI increases susceptibility to HFD‑induced hepatic tumorigenesis in males, suggesting that LDI may cause a potential developmental disruption that creates a latent vulnerability manifesting later in life.

Purpose:In this study, we evaluated 90 bioinformatics pipelines using RNA-Seq datasets from Rats, Zebrafish and Mice. The analysis was conducted in the context of weak signals, including exposure to metallic particles (tungsten), low-dose radiation or medical treatment. RNA-Seq data analysis involves several critical steps, from quality control to differential expression analysis, each offering multiple algorithmic options. Selecting the optimal pipeline is particularly challenging in complex scenarios with weak signals.We applied a dual strategy based on two complementary approaches to rank and evaluate the performance of these pipelines. The first approach, a widely used method, is based on the correlation between RNA-Seq and qRT-PCR expression data to ensure the direct validation of RNA-Seq results. The second approach leverages machine learning classifiers to rank the pipelines based on their ability to distinguish between exposure groups. This dual strategy was designed to identify the most reliable pipelines capable of providing accurate biological insights, with the top-performing pipeline highlighting key biological processes linked to a weak signal. Results:Our results highlight the crucial role of pipeline selection in RNA-Seq studies, as it influences both analysis efficiency and biological insights. While our findings are particularly relevant for studies with weak RNA-Seq signals, the ranking methods we employed can be applied in other fields to identify the most appropriate pipeline for generating biologically meaningful data. We provide practical recommendations for bioinformaticians to select robust pipelines, ensuring reliable and insightful outcomes across various research contexts, including environmental exposures. Conclusions:RNA-Seq pipelines that are effective for strong signals may fail with weak signals or noisy RNA-seq data. Our classifier-based ranking approach is still particularly useful, even when the sequencing depth is lower. Pipelines' sensitivity has a greater impact on counting and normalization than on trimming and mapping. StringTie should be prioritized as a counting method for data with weak signals.

Background:Infertility is a significant public health issue that can be influenced by environmental pollutants. As a radioactive heavy metal and environmental contaminant, uranium has the potential to impact fertility. Objective:This study assesses the multigenerational reproductive effects of chronic, non-nephrotoxic uranium exposure across three generations of male rats. Methods:In this study, a non-nephrotoxic uranium solution (40 mg/L) was chronically administered via drinking water to male and female F0 rats (n = 20 per group) throughout their lifespan. The objective was to evaluate the potential reprotoxic effects of uranium on males across three generations (F0, F1, F2), with a focus on spermatogenesis, steroidogenesis, and testicular homeostasis, including oxidative stress, inflammation, apoptosis, and vitamin D metabolism. Results:Steroidogenesis was modulated in all generation, with dysregulation of sex and pituitary hormones (testosterone, estradiol, gonadotropins, Luteinizing Hormone (LH), Follicle-Stimulating Hormone (FSH). Morphological and histological changes in the testes were observed in both the F1 and F2 generations. Spermatogenesis was dysregulated by an increased proportion of seminiferous tubules at stage I-VI and reduced expression of TH2B and eppin mRNA. Interestingly, gene expression analysis of several markers involved in the regulation and protection of testicular homeostasis revealed significant effects only on the F2 generation. In this generation, uranium exposure also disrupted vitamin D metabolism in the testes. Conclusion:Uranium may impair testicular function, with more pronounced effects observed in the F2 generation. These findings highlight its potential for multigenerational toxicity and underscore the need for further research into its impact on human reproductive health.

A radiological accident may result in the development of a local skin radiation injury (LRI) which may evolve, depending on the dose, from dry desquamation to deep ulceration and necrosis through unpredictable inflammatory waves. Therefore, early diagnosis of victims of LRI is crucial for improving medical care efficiency. This preclinical study aims to identify circulating metabolites as biomarkers associated with LRI using a C57BL/6J mouse model of hind limb irradiation. More precisely, two independent mice cohorts were used to conduct a broad-spectrum profiling study followed by a suspect screening analysis performed on plasma metabolites by mass spectrometry. An integrative analysis was conducted through a multi-block sparse partial least square discriminant analysis (sPLS-DA) to establish multi-scale correlations between specific metabolites levels and biological, physiological (injury severity), and functional parameters (skin perfusion). The identified biomarker signature consists in a 6-metabolite panel including putrescine, uracil, 2,3-dihydroxybenzoate, 3-hydroxybenzoate, L-alanine and pyroglutamate, that can discriminate mice according to radiation dose and injury severity. Our results demonstrate relevant molecular signature associated with LRI in mice and support the use of plasma metabolites as suitable molecular biomarkers for LRI prognosis and diagnosis.

The presence of Cesium-137 (137Cs) in the environment after nuclear accidents at Chernobyl and Fukushima Daiichi raises many health issues for the surrounding populations chronically exposed through the food chain. Unlike previous in vivo studies that focused solely on male exposures, this experimental research aims to assess the biodistribution and dosimetry of low-dose 137Cs internal exposure in both male and female C57BL/6 mice. This study uses a previously established model for chronic ingestion of 137Cs, simulating various exposure scenarios. Male and female C57BL/6 mice were exposed to concentrations resembling those ingested daily by residents in contaminated areas (20 kBq/L), as well as 5- and 10-times higher concentrations, for either 6 or 24 weeks. These exposure periods were chosen to assess both short-term and long-term effects of chronic 137Cs exposure, allowing us to observe differences in 137Cs accumulation and elimination in mice. Throughout this period, the animals were closely monitored to determine and quantify the 137Cs content and to calculate absorbed doses. After 6 or 24 weeks exposure to chronic 137Cs in drinking water at 500 kBq/L, 137Cs concentration varied according to the organs and the sex of the animals. Males showed a higher body burden of 137Cs compared to females, with significant differences observed as soon as day 11. As well, the organs showing the highest 137Cs concentrations were skeletal muscle in males and in females, with significant differences between males and females. Regarding excretion, it appears that the elimination of 137Cs through feces was similar in males and females. By contrast, female mice showed a higher rate of 137Cs urine excretion than males, thus explaining the lower body burden in females. The resulting absorbed doses, calculated using dose conversion factors provided by ICRP publication 108, showed that the absorbed dose is 1.85 times less in female mice compared to male mice. 36.1 mGy in females and 66.9 mGy in males after 6 weeks exposure. 182.0 mGy in females and 310.0 mGy in males after 24 weeks exposure. This study demonstrates for the first time, sexual dimorphism in 137Cs biokinetics between males and females. These findings could refine biokinetic models of cesium and absorbed dose estimations in case of internal contamination, especially in post-accidental situations.

While AI is widely used in biomedical research and medical practice, its use is constrained to few specific practical areas, e.g., radiomics. Participants of the workshop on “Artificial Intelligence in Biology and Medicine” (Jerusalem, Feb 14–15, 2023), both researchers and practitioners, aimed to build a holistic picture by exploring AI advancements, challenges and perspectives, as well as to suggest new fields for AI applications. Presentations showcased the potential of large language models (LLMs) in generating molecular structures, predicting protein-ligand interactions, and promoting democratization of AI development. Ethical concerns in medical decision making were also addressed. In biological applications, AI integration of multi-omics and clinical data elucidated the health relevant effects of low doses of ionizing radiation. Bayesian latent modeling identified statistical associations between unobserved variables. Medical applications highlighted liquid biopsy methods for non-invasive diagnostics, routine laboratory tests to identify overlooked illnesses, and AI's role in oral and maxillofacial imaging. Explainable AI and diverse image processing tools improved diagnostics, while text classification detected anorexic behavior in blog posts. The workshop fostered knowledge sharing, discussions, and emphasized the need for further AI development in radioprotection research in support of emerging public health issues. The organizers plan to continue the initiative as an annual event, promoting collaboration and addressing issues and perspectives in AI applications with a focus on low-dose radioprotection research. Researchers involved in radioprotection research and experts in relevant public policy domains are invited to explore the utility of AI in low-dose radiation research at the next workshop.

PURPOSE:The radiation protection community has been particularly attentive to the risks of delayed effects on offspring from low dose or low dose-rate exposures to ionizing radiation. Despite this, the current epidemiologic studies and scientific data are still insufficient to provide the necessary evidence for improving risk assessment guidelines. This literature review aims to inform future studies on multigenerational and transgenerational effects. It primarily focuses on animal studies involving in utero exposure and discusses crucial elements for interpreting the results. These elements include in utero exposure scenarios relative to the developmental stages of the embryo/fetus, and the primary biological mechanisms responsible for transmitting heritable or hereditary effects to future generations. The review addresses several issues within the contexts of both multigenerational and transgenerational effects, with a focus on hereditary perspectives. CONCLUSIONS:Knowledge consolidation in the field of Developmental Origins of Health and Disease (DOHaD) has led us to propose a new study strategy. This strategy aims to address the transgenerational effects of in utero exposure to low dose and low dose-rate radiation. Within this concept, there is a possibility that disruption of epigenetic programming in embryonic and fetal cells may occur. This disruption could lead to metabolic dysfunction, which in turn may cause abnormal responses to future environmental challenges, consequently increasing disease risk. Lastly, we discuss methodological limitations in our studies. These limitations are related to cohort size, follow-up time, model radiosensitivity, and analytical techniques. We propose scientific and analytical strategies for future research in this field.

Exposure to environmental pollution and the increase in the incidence of multifactorial diseases in the population have become health problems for industrialized countries. In this context, the question of the health impact of exposure to these pollutants is not clearly identified in the low-dose range. This article looks at this problem using the example of preclinical studies of the effects of chronic low-dose exposure to uranium in rats. These studies demonstrate the value of molecular screening analyses (omics) and multimodal integrative approaches, of which the extreme sensitivity and breadth of observation spectrum make it possible to observe all the biological processes affected and the mechanisms of action triggered at the molecular level by exposure to low doses. They also show the value of these analytical approaches for finding diagnostic biomarkers or indicators of prognosis, which can be necessary to evaluate a risk. Finally, the results of these studies raise the question of the health risk caused by epigenomic deregulations occurring during critical developmental phases and their potential contribution to the development of chronic diseases that are metabolic in origin or to the development of certain cancer liable in the long term to affect the exposed adult and possibly its progeny.

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.

Changes in metabolomics over time were studied in rats to identify early biomarkers and highlight the main metabolic pathways that are significantly altered in the period immediately following acute low-dose uranium exposure. A dose response relationship study was established from urine and plasma samples collected periodically over 9 months after the exposure of young adult male rats to uranyl nitrate. LC-MS and biostatistical analysis were used to identify early discriminant metabolites. As expected, low doses of uranium lead to time-based non-toxic biological effects, which can be used to identify early and delayed markers of exposure in both urine and plasma samples. A combination of surrogate markers for uranium exposure was validated from the most discriminant early markers for making effective predictions. N-methyl-nicotinamide, kynurenic acid, serotonin, tryptophan, tryptamine, and indole acetic acid associated with the nicotinate–nicotinamide and tryptophan pathway seem to be one of the main biological targets, as shown previously for chronic contaminations and completed, among others, by betaine metabolism. This study can be considered as a proof of concept for the relevance of metabolomics in the field of low-dose internal contamination by uranium, for the development of predictive diagnostic tests usable for radiotoxicological monitoring.

Context: Participatory research in environmental health remains rare in France. The objectives of environmental health research projects can, like their methods, be very diverse. Opportunities for greater involvement of civil society, as well as its challenges, differ at each step of such research activities. All these aspects need to be widely shared. As a preparatory step toward the development of concrete new participatory research projects on multiple environmental exposures, the LILAS project aimed to (1) favor the mutual understanding of the main issues and research methods in environmental health and their stakes for different participants, but also the requirements, strengths, and limitations of these methods, and (2) identify the expected benefits and points to watch out for related to stronger civic participation in these projects. Methods: The LILAS project identified and gathered together institutional researchers, academics and civil society participants (mainly from nongovernmental organizations) interested in multiple exposures (chemical and radiological). The relevant literature was searched to learn from previous participatory research projects in this broad field. Several meetings enabled the group to collectively identify different types of studies and analyze the benefits, limitations and methods related to the introduction of such participation. An analysis matrix was co-constructed and completed by study participants, as in a Living Lab approach. Results: The matrix lists for different types of studies (assessment of environmental exposures, identification of their determinants, interventions on these exposures, quantitative risk assessment, epidemiological studies, experimental research, ecosystem health, etc.) the expected benefits for several categories of stakeholders, the fundamental principles of research methods, and their related practical constraints, advantages and limitations related to the use of participatory or more standard approaches. Conclusion: The LILAS project enabled the development of a solid basis for the co-construction of participatory research projects to study multiple environmental exposures.

BACKGROUND AND AIM: Participatory research in environmental health is still rare in France. The objectives of environmental health research, in general, can be very diverse (e.g.: identifying situations associated with risks estimating exposures and effects, testing the effectiveness of preventive actions) and related methods are diverse as well. Opportunities for greater implication of the civil society and related challenges differ at each step of research activities. These aspects need to be better known and shared collectively. The LILAS project aimed to 1) co-construct, among institutional researchers, academics and civil society representatives, a mutual understanding of the main problematics and research methods in environmental health, their stakes for different actors, but also the requirements, strengths and limitations of these methods 2) identify expected benefits and points of vigilance related to stronger degrees of participation as part of such environmental health research projects. METHODS: LILAS gathered institutional researchers, academics and civil society representatives interested in multiple exposures (chemical, radiological). Several meetings allowed to collectively identify different types of study (including environmental epidemiological studies) and reflect about the added value, limitations, and methodological principles related to the introduction of growing participation as part of such studies. An analysis matrix was co-created and filled by participants. RESULTS:For different types of studies (studies for assessment of environmental exposures, identification of their determinants, interventions on these exposures, development of sensors, quantitative risk assessment, environmental epidemiological studies, experimental research, studies on the health of ecosystems…), the matrix lists expected benefits for several categories of stakeholders, fundamental methodological principles and practical constraints, advantages and limitations related to the use of participatory approaches (such as the living lab one) or more "classical" approaches. CONCLUSIONS:LILAS has allowed, through a cross-acculturation process, to develop consolidated grounds for the co-construction of future participatory research projects on multiple environmental exposures. KEYWORDS: Key-words: Multiple exposures, participatory research, methods in environmental health research, Living Lab, co-creation,

This study developed an in vivo protocol of chronic uranium exposure to examine the biological effects of these chronic exposures to the low doses to which human populations may be exposed; it used omics analysis as well as conventional clinical monitoring. Metabolomics analysis revealed an observable sexual dimorphism in the kidneys, urine, and blood plasma of exposed animals. It also showed that the metabolisms most strongly affected were those of nicotinate-nicotinamide and of unsaturated fatty acid biosynthesis. Upstream of the metabolism, transcriptomic analyses of the kidney revealed genetic and epigenetic responses to uranium. At the epigenetic level, analysis of kidney DNA methylation revealed that this methylation increased for two generations of males born to a female exposed while pregnant (while DNA methylation of female offspring kidneys was not affected). A multiscale analysis of the metabolomic and transcriptomic findings showed new molecular pathways associated with uranium exposure. These multiscale analyses could be relevant for decrypting the biological mechanisms of low-dose exposures. Finally, these results highlight the importance of `gender in estimating sensitivity to low-dose exposure and draw attention to the need to take this component into account in risk assessment.

Contexte Les recherches participatives en sante-environnement restent peu developpees en France. Les objectifs poursuivis de maniere generale par les recherches en sante-environnement (ex : identifier des situations potentiellement a risque, estimer des expositions, evaluer des effets, tester des actions preventives) et les methodes employees a ces fins sont varies. Les opportunites d’une plus grande implication de la societe civile et defis associes different a chaque etape de ces recherches. Ces aspects demandent a etre mieux apprehendes collectivement. Le projet LILAS vise, en amont du developpement de futurs projets de recherches participatives sur les multi-expositions environnementales, a 1) co-construire, entre chercheurs institutionnels, academiques et representants de la societe civile, une bonne comprehension commune des principales problematiques et methodes de recherche en sante-environnement, de leurs enjeux, prerequis, forces et limites 2) identifier les benefices et points de vigilance lies a l’introduction de plus fortes dimensions participatives dans ces recherches. Methode adoptee Le projet LILAS a rassemble des chercheurs institutionnels, academiques et representants de la societe civile interesses par les multi-expositions (chimiques, radiologiques). Une recherche bibliographique a ete initiee pour tirer le retour d’experience de projets de recherches participatives en sante-environnement. Plusieurs reunions ont permis d’identifier collectivement differents types d’etudes et de reflechir sur les apports, limites et principes methodologiques relatifs a l’introduction de differents degres de participation dans celles-ci. Une matrice d’analyse a ete co-construite puis alimentee par les participants, en s’inspirant des approches « Living Lab ». Resultats Pour differents types d’etudes (etudes d’evaluations d’expositions, d’identification de leurs determinants, tests d’interventions sur ceux-ci, developpement de capteurs, evaluations de risques sanitaires, etudes epidemiologiques, recherches experimentales, etudes sur la sante des ecosystemes…), la matrice liste les benefices attendus pour plusieurs categories de parties prenantes, les principes methodologiques fondamentaux et contraintes pratiques, les avantages et limites relatifs a l’emploi d’approches participatives (comme l’approche Living Lab) ou plus “classiques”, mais egalement les besoins d’accompagnements institutionnels et les effets structurants necessaires a leur deploiement et leur amelioration qualitative. Conclusion LILAS a permis, par acculturation croisee, de poser des bases consolidees pour la co-construction de futurs projets de recherches participatives sur les multi-expositions environnementales.

Purpose: To examine the effects of low-dose exposure to uranium with a systems biology approach, a multiscale high-throughput multi-omics analysis was applied with a protocol for chronic exposure to the rat kidney.Methods: Male and female rats were contaminated for nine months through their drinking water with a nontoxic solution of uranyl nitrate. A multiscale approach enabled clinical monitoring associated with metabolomic and transcriptomic (mRNA and microRNA) analyses.Results: A sex-interaction effect was observed in the kidney, urine, and plasma metabolomes of contaminated rats. Moreover, urine and kidney metabolic profiles correlated and confirmed that the primary dysregulated metabolisms are those of nicotinate-nicotinamide and of unsaturated fatty acid biosynthesis. Upstream of the metabolic pathways, transcriptomic profiles of the kidney reveal gene activity focused on gene regulation mechanisms, cell signaling, cell structure, developmental processes, and cell proliferation. Examination of epigenetic post-transcriptional gene regulation processes showed significant dysregulation of 70 micro-RNAs. The multi-omics approach highlighted the activities of the cells' biological processes on multiple scales through analysis of gene expression, confirmed by changes observed in the metabolome.Conclusion: Our results showed changes in multi-omic profiles of rats exposed to low doses of uranium contamination, compared with controls. These changes involved gene expression as well as modifications in the transcriptome and the metabolome. The metabolomic profile confirmed that the main molecular targets of uranium in kidney cells are the metabolism of nicotinate-nicotinamide and the biosynthesis of unsaturated fatty acids. Additionally, gene expression analysis showed that the metabolism of fatty acids is targeted by processes associated with cell function. These results demonstrate that multiscale systems biology is useful in elucidating the most discriminative pathways from genomic to metabolomic levels for assessing the biological impact of this low-level environmental exposure, i.e. the exposome.

Background: Nuclear power plant emergencies had often been accompanied by radioactivity release into the environment, thyroid cancer is one of the major health consequences due to the effect of radioactive iodine (131I) that emits ϒ ray and β particles resulting in thyroid DNA damage and late onset thyroid cancer. Intake of a single dose of potassium iodide (KI) is recommended to reduce this risk. However in case of prolonged radioiodine release as noticed during Chernobyl and Fukushima accidents, more than one dose of KI may be basic to ensure adequate protection [1]. Whereas a single dose of KI is admitted to be safe, knowledge about the effects of repeated KI administration are scarce, few studies demonstrated the potential efficiency of repetitive KI intake in humans [2] and non-human primates [3] without hormonal variations. These studies are relevant in the field of radiation protection and give a base evidence of the possible use of repetitive KI. On the other hand, we have studies on rodents that showed an impact of chronic iodine excess on pituitary thyroid axis function [4]. Our previous work on adult male rats demonstrated the safety of repeated administration of KI over 8 days [5]. Indeed in the elderly persons KI administration in case of nuclear emergency remains a topic of debate, because of the possible impact in cardiovascular diseases. Thyroid hormones are well-known for their profound effects on cardiovascular function and metabolism; myocardial and vascular endothelial tissues have receptors for thyroid hormones and are sensitive even to subtle changes in the concentrations of circulating pituitary and/or thyroid hormones i.e. subclinical hypothyroidism and hyperthyroidism. It is well established that hyperthyroidism induces a hyper-dynamic cardiovascular state, which is associated with a faster heart rate, enhanced left ventricular systolic and diastolic function whereas hypothyroidism is characterized by the opposite changes. Atrial fibrillation is the most common cardiac arrhythmia in the elderly, the prevalence and incidence increase with advancing age [6]. Several interventional trials showed that treatment of subclinical thyroid diseases improves cardiovascular risk factors, which implies potential benefits for reducing cardiovascular events. Objective: The aim of this study is to assess the effects of repeated KI intake on the thyroid function of aged male rats. Methods: A twelve months old male rats were subjected to either KI or saline solution over 8 days. Clinical biochemistry, pituitary and thyroid hormones level, and thyroid genes expression were analyzed 30 days after the treatment discontinuation. Findings: urinary assessment shows a subtle increase of some parameters (Creatinin, Uric Acid, Urea, Glucose, Potassium, Sodium and Chlorine), plasma biochemistry reveals a subtle variation of some parameters (an increase of Creatinin, Glucose and phosphorus; and a decrease of Chlorine level). Regarding pituitary-thyroid hormones we get a significant decrease of TSH level without thyroid hormones variation. At the molecular level, we observe a significant increase of TPO (+100%), AIT (+299%) and Tg (+38%) mRNA expression. On the other hand we get a significant decrease of TSHR (-51%) mRNA expression. Conclusion and perspectives: Our first results indicate that repeated KI intake affects the clinical biochemistry and the pituitary-thyroid axis function in elderly rats. To go further we are investigating the impact of these variations on the cardiovascular function and its parameters. Cardiac output data, cardiovascular gene expression, oxidative stress and inflammatory analysis are being processed. This study will contribute to the evolution of iodine policy and the harmonization of the current KI guidelines.

Protracted radioiodine release may require repeated intake of potassium iodide (KI) to protect thyroid gland. It is well established that iodine excess inhibits transiently the thyroid function. As developing fetus depends on maternal thyroid hormones (TH) supply, more knowledge is needed about the plausible effects that repeated KI intake can cause in this sensitive population, especially that even subtle variation of maternal thyroid function may have persistent consequences on progeny brain processing. The aim of this study is to assess the consequences of repeated intake of KI during pregnancy on the progeny's thyroid function and brain development. To do so pregnant Wistar rats received KI over eight days, and then thirty days after the weaning, male progeny was subjected to behavior test. Pituitary and thyroid hormones level, anti-thyroid antibodies level, organs morphology, gene expression and global DNA methylation were assessed. Thirty days after the weaning, KI-exposed male progeny showed an uncommon hormonal status, characterized by a decrease of both thyroid-stimulating hormone (−28%) and free thyroxine (−7%) levels. Motor coordination was altered in KI-exposed male progeny. At the cerebellar level, we observed a decrease of mRNA expression of DCX (−42%) and RC3 (−85%); on the other hand, at the cortical level, mRNA expression of MBP (+71%), MOBP (+90%) and Kcna1 (+42%) was increased. To conclude, repeated KI prophylaxis is not adequate during pregnancy since it led to long-term irreversible neurotoxicity in the male progeny.

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.