Reproductive Toxicology Research Articles

Risque génotoxique et ovocytes : principes de toxicologie génétique et applications

The aim of genotoxicity tests in germ cells is to assess the impact of exposure to environmental mutagens that may represent a risk for the fertility or for the offspring of exposed subject. The comet assay on mature mouse oocytes is a simple, reproductive and rapid test to study primary DNA damage in oocytes. This test is used to complete toxicology assays applied in first line to somatic cells, and could find many applications in reproductive toxicology to study impact of environmental factors on female germ cells. We describe a practical application of comet assay in reproductive biology to assess the genotoxicity of cryoprotectants used at high concentrations in oocyte vitrification protocols. This test allowed us to demonstrate that dimethylsulfoxide and ethylene glycol are non-genotoxic for the mouse oocytes and led us to hypothesize a genotoxic effect of 1,2-propanediol (PrOH) at high concentrations after having observed induction of significant DNA damage on CHO cell line and on mouse oocytes.

Reproductive Effects of Two Neonicotinoid Insecticides on Mouse Sperm Function and Early Embryonic Development In Vitro

Acetamiprid (ACE) and imidacloprid (IMI) are two major members in the family of neonicotinoid pesticides, which are synthesized with a higher selectivity to insects. The present study determined and compared in vitro effects of ACE, IMI and nicotine on mammalian reproduction by using an integrated testing strategy for reproductive toxicology, which covered sperm quality, sperm penetration into oocytes and preimplantation embryonic development. Direct chemical exposure (500 µM or 5 mM) on spermatozoa during capacitation was performed, and in vitro fertilization (IVF) process, zygotes and 2-cell embryos were respectively incubated with chemical-supplemented medium until blastocyst formation to evaluate the reproductive toxicity of these chemicals and monitor the stages mainly affected. Generally, treatment of 500 µM or 5 mM chemicals for 30 min did not change sperm motility and DNA integrity significantly but the fertilization ability in in vitro fertilization (IVF) process, indicating that IVF process could detect and distinguish subtle effect of spermatozoa exposed to different chemicals. Culture experiment in the presence of chemicals in medium showed that fertilization process and zygotes are adversely affected by direct exposure of chemicals (P<0.05), in an order of nicotine>IMI>ACE, whereas developmental progression of 2-cell stage embryos was similar to controls (P>0.05). These findings unveiled the hazardous effects of neonicotinoid pesticides exposure on mammalian sperm fertilization ability as well as embryonic development, raising the concerns that neonicotinoid pesticides may pose reproductive risks on human reproductive health, especially in professional populations.

Use of quetiapine in child and adolescent populations – Response to letter from Dr Lambe

Australian & New Zealand Journal of Psychiatry, 47(11) Gentile S and Galbally M (2010) Prenatal exposure to antidepressant medications and neurodevelopmental outcomes: A systematic review. Journal of Affective Disorders 128: 1–9. Grigoriadis S, Vonderporten EH, Mamisashvili L, et al. (2013) Antidepressant exposure during pregnancy and congenital malformations: is there an association? a systematic review and meta-analysis of the best evidence. Journal of Clinical Psychiatry 74: e293–e308. Lewis A, Galbally M and Bailey C (2012) Perinatal mental health, antidepressants and neonatal outcomes: Findings from the Longitudinal Study of Australian Children. Neonatal, Paediatric and Child Health Nursing 15: 22–28. Malm H, Artama M, Gissler M, et al. (2011) Selective serotonin reuptake inhibitors and risk for major congenital anomalies. Obstetrics & Gynecology 118: 111–120. Myles N, Newall H, Ward H and Large M (2013) Systematic meta-analysis of individual selective serotonin reuptake inhibitor medications and congenital malformations. Australian and New Zealand Journal of Psychiatry 47: 1001–1011. O’Brien L, Einarson TR, Sarkar M, et al. (2008) Does paroxetine cause cardiac malformations? Journal of Obstetrics and Gynaecology Canada 30: 696–701. Rahimi R, Nikfar S and Abdollahi M (2006) Pregnancy outcomes following exposure to serotonin reuptake inhibitors: A meta-analysis of clinical trials. Reproductive Toxicology 22: 571–575. Wurst KE, Poole C, Ephross SA, et al. (2010) First trimester paroxetine use and the prevalence of congenital, specifically cardiac, defects: A meta-analysis of epidemiological studies. Birth Defects Research. Part A, Clinical and Molecular Teratology 88: 159–170.

Nanosilver: Weighing the Risks and Benefits

It takes a special sort of case to spur attorneys into a debate over the drooling habits of toddlers. Yet that’s where lawyers from the Natural Resources Defense Council (NRDC), the U.S. Environmental Protection Agency (EPA), and Swiss chemicals company HeiQ found themselves in January 2013 as they debated in a federal appeals court the extent to which 1-year-olds and 3-year-olds chew, salivate, and swallow.1 At issue in the NRDC’s suit against the EPA, which is still awaiting ruling, was whether the agency was right in granting a conditional registration in December 2011 to a nanosilver-based antimicrobial fabric treatment manufactured by HeiQ.2 The EPA’s risk assessment was based in part on assumptions about exposure of 3-year-olds by sucking or chewing on nanosilver-laced textiles such as clothing, blankets, and pillowcases. Silver nanoparticles are added to a variety of textiles and home goods as an antimicrobial. Although silver has been used safely for centuries, some question whether the rapid expansion of new exposure sources to nanosilver could have adverse consequences. ... NRDC lawyer Catherine Rahm, however, begged to differ with the agency’s methods. In the January hearing, she argued that the agency record shows infants are more likely than any other subset of children to chew on fabrics that could contain the pesticide, and that if the agency were to recalculate its risk assessment based on the body weight of a 1-year-old, nanosilver concentrations in HeiQ’s product could result in potentially harmful exposures. It’s an obscure but critical distinction as far as risk assessment goes. And given the implications for HeiQ and other companies looking to follow in its footsteps, the case has landed at the center of a prolonged conflict over the regulation of nanosilver and the growing deployment of this antimicrobial ingredient in a variety of commercial and consumer products. Yet regardless of which side prevails in the case, the truth about nanosilver is not black and white. Even the loudest voices joining the NRDC’s call for strict regulation of nanosilver concede that context is key. “I’m not somebody who is for or against nano,” says Ian Illuminato, who directs Friends of the Earth’s U.S. nanotechnology campaign, which has produced a series of reports on the potential dangers of nanosilver and other nanomaterials. “I’m just saying we need to do this in a mature and adult way. That’s not to say this isn’t a helpful technology and it doesn’t have a place in our future, but in the way it’s evolving right now, it’s very risky.” Greg Lowry, a researcher at Carnegie Mellon University who studies the fate of nanoparticles in the environment, agrees that the use of nanosilver is a matter of balancing risk and reward. “There’s a tremendous potential benefit to the use in some of these products,” he says. “What one has to do is to ask yourself whether the benefits outweigh the risk.”

A retrospective analysis of pathological changes of testicular tissue in normal adult rats

Rat testicular model is widely used in experiments on andrology, pharmacology and reproductive toxicology. Generally, normal adult rat is considered to have normal testes. However, whether normal adult rats appeared abnormal testes have not been evaluated. The objective of this study was to evaluate the incidence of abnormal testes in normal adult Sprague Dawley (SD) rats and pathological changes in testicular tissues. Six hundred and sixteen adult male SD rats used in previous studies as controls were retrospectively analysed. Testicular tissues were stained with haematoxylin-eosin for observation of pathology. Among 616 rats, 14 rats had pathological testes, and the incidence of abnormal testis was 2.3%. In the 14 rats with abnormal testes, 10 rats were microrchidia (71.4%) and four rats showed normal testicular size. Testicular abnormality included complete interruption of spermatogenesis, partial germ cell arrest, progressive hypospermatogenesis, seminiferous epithelia vacuolation and inflammatory status. Bilateral testicular tissues had similar pathological changes in abnormal testes. The findings in this study demonstrate that the normal adult rats have abnormal testes. We should pay attention to the possibility of abnormal testes when using normal adult male rats for establishing a testicular model.

Nanomaterial interference with early human placenta: Sophisticated matter meets sophisticated tissues

Next to nothing is known about nanoparticle and nanofiber trafficking at the feto-maternal interface in early human pregnancy. As the first trimester is thought to be crucial for the further placental and fetal development, it will be important to assess the possible risks of nanomaterial exposures during this period. There are some intriguing observations in nanotoxicology, however, indicating certain differences between classical toxicology and nanotoxicology. To understand nanomaterial-biokinetics and placental toxicity in early gestation, the special architecture, the hypoxic condition, the bilayer of villous trophoblast, the plugging of spiral arteries and the contribution of intrauterine glands to nutrition, as well as the delicate immunologic situation at the implantation site, will have to be considered. Unless nano-specific biokinetics are properly understood, it will be difficult to ensure identification of potential “nano-thalidomides” among all the newly engineered nanoparticles and fibers, based on the models available in reproductive toxicology.

Minipigs: Applications in Toxicology

AbstractMinipigs are accepted models for a variety of drug preclinical and nonregulatory toxicology studies. Acute, subchronic and chronic studies are possible using all routes of administration. Minipigs have distinct size advantages over domestic pigs. There exist some minor limitations with minipigs, but for the most part they offer well correlated models to humans for dermal and systemic toxicology assessments. Phototoxicology and reproductive toxicology usage is expanding. Minipig size, anatomy, physiology, metabolism, and genetics generally correlate well to human factors. The minipig makes an appropriate model for toxicology. Curr. Protoc. Toxicol. 56:1.11.1‐1.11.19. © 2013 by John Wiley &amp; Sons, Inc.

Pharmaceutical toxicology: Designing studies to reduce animal use, while maximizing human translation

Evaluation of the safety of new chemicals and pharmaceuticals requires the combination of information from various sources (e.g. in vitro, in silico and in vivo) to provide an assessment of risk to human health and the environment. The authors have identified opportunities to maximize the predictivity of this information to humans while reducing animal use in four key areas; (i) accelerating the uptake of in vitro methods; (ii) incorporating the latest science into safety pharmacology assessments; (iii) optimizing rodent study design in biological development and (iv) consolidating approaches in developmental and reproductive toxicology. Through providing a forum for open discussion of novel proposals, reviewing current research and obtaining expert opinion in each of the four areas, the authors have developed recommendations on good practice and future strategy.

The Effects of Shipping on Early Pregnancy in Laboratory Rats

Although rats in various stages of pregnancy are routinely shipped by vendors, the effects of shipping on pregnancy outcomes have not been reported. This study examined the effects of shipping rats 1 day after mating. Two outbred stocks, (Crl:CD(SD), Crl:WI(Han)) and one inbred strain (F344/Crl) of rats (n=300/strain) were mated in a vendor barrier room at 3-month intervals five times, and either shipped the next day (total time in transit ∼24 hr) or held in the room of origin until parturition. The pregnancy status, length of gestation, number of pups born per female, sex ratio of pups born, and neonatal mortality were compared between transported and nontransported rats. These pregnancy and litter parameters were also compared among strains and examined for seasonality; no seasonal effects were observed. Neonatal mortality was negligible at less than 2% in any of the groups. All sex ratios were normal. Transportation affected pregnancy rates only in the F344/Crl, in which 81.8% of the nontransported versus 70% of the transported rats had pups (p=0.025). Overall, slightly fewer transported rats were pregnant, but they had larger litters (10.08 compared with 9.68, p=0.02, pooling across all three strains) so produced the same numbers of pups. A total of 77±8% of transported rats had gestation periods of 22 days or more compared with only 52±10% in the nontransported rats. The reason for larger litters in transported females is unclear. Longer gestation in transported females may be due to facultative embryonic diapause, which might have implications for reproductive toxicology.

Evaluation of an alternative in vitro test battery for detecting reproductive toxicants

The application of alternative methods in developmental and reproductive toxicology is challenging in view of the complexity of mechanisms involved. A battery of complementary test systems may provide a better prediction of developmental and reproductive toxicity than single assays. We tested twelve compounds with varying mechanisms of toxic action in an assay battery including 24 CALUX transcriptional activation assays, mouse cardiac embryonic stem cell test, ReProGlo assay, zebrafish embryotoxicity assay, and two CYP17 and two CYP19 activity assays. The battery correctly detected 11/12 compounds tested, with one false negative occurring, which could be explained by the absence of the specific mechanism of action of this compound in the battery. Toxicokinetic modeling revealed that toxic concentrations were in the range expected from in vivo reproductive toxicity data. This study illustrates added value of combining assays that contain complementary biological processes and mechanisms, increasing predictive value of the battery over individual assays.

Effects of chlorpyrifos on reproductive toxicology of male rats

The aim of this study is to investigate the effects of subchronic exposure to chlorpyrifos on reproductive toxicology of male rats. Forty healthy male rats were divided into four groups: three exposure groups and a control group. Chlorpyrifos was administered orally to male rats at 0, 2.7, 5.4, and 12.8 mg/kg for 90 days to evaluate the toxic alterations in testicular histology, testicular marker enzyme activities and related genes expression levels, sperm dynamics, and testosterone levels. The body weight and the testis weight of animals did not show any significant changes. Chlorpyrifos brought about marked reduction in testicular sperm counts, sperm motility, and significant growth of sperm malformation rate in exposed males. Histopathological examination of testes showed mild to severe degenerative changes in seminiferous tubules at various dose levels. The levels of testosterone (T) showed a decreasing tendency, and there was a statistical difference between the 5.4, 12.8 mg/kg groups, and the control group. The levels of follicle stimulating hormone (FSH) were significantly increased in 5.4 and 12.8 mg/kg groups, but there were no obvious effects on the levels of luteinizing hormone (LH) and estradiol (E2 ). A significant increase in the activities of LDH and LDH-x was observed in chlorpyrifos exposed rats in 5.4 and 12.8 mg/kg groups, but the expression levels of related genes had no significant differences between chlorpyrifos exposure groups and the control group. These results suggest that chlorpyrifos has adverse effects on reproductive system of male rats.

Translocation, transfer, and in vivo safety evaluation of engineered nanomaterials in the non-mammalian alternative toxicity assay model of nematode Caenorhabditis elegans

Translocation, transfer, and safety evaluation of engineered nanomaterials in non-mammalian alternative assay model of Caenorhabditis elegans are summarized and discussed. Due to the extensive applications of engineered nanomaterials (ENMs) in industry, agriculture, medicine and public health, environmental exposure of ENMs to human and environmental organisms is inevitable, therefore studies on translocation, transfer, and toxicology of ENMs receive wide interest. Modelling the nematode C. elegans, a widely recognized non-mammalian alternative toxicity assay system has been proven to be valuable in environmental safety evaluation, toxicological study, and examination of translocation and transfer of toxicants. In this review, we summarize and discuss the values and contributions of C. elegans in studies on environmental safety evaluation, toxicology, and translocation and transfer of ENMs. We introduced acute and chronic toxicity assay systems and discussed environmental safety assessment of specific ENMs at predicted environmental relevant concentrations, and influences of chemical properties of ENMs, exposure routes, developmental, genetic or physiological state, and environmental factors on nanotoxicity formation in nematodes. We then discussed the toxicological mechanisms of ENMs mainly with respect to roles of oxidative stress in normal and stress conditions and signaling pathways, reproductive toxicology, neurotoxicology, and translocation, distribution, transfer and metabolism of ENMs in C. elegans. Ways to eliminate or reduce the toxicities of specific ENMs by chemical modification with surface designs were further discussed. Finally, four important challenges have been raised and discussed by surrounding the aspects of environmental safety assessment, toxicological mechanisms, and designs of new safe ENMs.

Peer consultation on relationship between PAC profile and toxicity of petroleum substances

An expert peer consultation panel reviewed a report by the PAC Analysis Task Group, which hypothesized that systemic, developmental, and reproductive toxicity observed in repeated-dose dermal toxicity studies was related to polycyclic aromatic compound (PAC) content. Peer consultations seek to solicit scientific and technical input from experts on the scientific basis and merits of the subject report. This peer consultation panel included nine scientists with expertise in petroleum chemistry, biostatistics, toxicology, risk assessment, structure activity, and reproductive and developmental toxicology. The panel evaluated the technical quality of the PAC report and provided recommendations for improving the statistical and biological approaches. The PAC report authors revised their methods and documentation, which are published elsewhere in this supplement. A review of the post peer consultation manuscripts confirmed that many of the key suggestions from expert panel members were considered and incorporated. In cases where the PAC report authors did not fully incorporate panel suggestions from the peer consultation, they have provided an explanation and support for their decision. This peer consultation demonstrates the value of formal engagement of peers in development of new scientific methods and approaches.

Estimating brood‐specific reproductive inhibition potency in aquatic toxicity testing

Effluents may contain chemicals that impact the mortality, growth, or reproduction of organisms in aquatic systems. A common endpoint analyzed in reproduction toxicology is the total young produced by organisms exposed to toxicants. In the present study, we propose using two Bayesian hierarchical models to analyze the brood‐specific reproduction count responses in aquatic toxicology experiments jointly and to estimate the brood‐specific concentration associated with a specified level of reproductive inhibition. A simulation study showed that the proposed models outperformed an approach where brood‐specific responses were modeled separately. In particular, this method provided potency estimates with smaller bias/variation and better coverage probability. The application of the proposed models is illustrated with an experiment where the impact of Nitrofen was studied. Copyright © 2012 John Wiley &amp; Sons, Ltd.

Assessment of the adverse effects of the acaricide amitraz: in vitro evaluation of genotoxicity

Amitraz is a formamidine widely used in Veterinary Medicine for the treatment of ectoparasites. It is a highly liposoluble compound that is quickly absorbed through the skin and mucous membranes, thus making exposure potentially dangerous for humans and animals. The aim of this study was to compare the genotoxic potential of the active constituent of the insecticide amitraz and a commercial product containing amitraz in vitro in hamster cells. The induction of primary DNA damage was evaluated by alkaline single-cell gel electrophoresis (comet assay) and the apoptotic ability was examined by the Annexin V/propidium iodide staining assay. The commercial formulation significantly increased the index of DNA damage at concentrations of 2.50–3.75 µg/mL compared to the control. The active constituent only induced significant DNA damage with the highest concentration (3.75 µg/mL). Although both tested products increased the frequency of cell death, neither of them induced significant differences. Genotoxic potential is a primary risk factor for long-term effects such as carcinogenic and reproductive toxicology. Results presented here highlight the need for further investigation of the potential health risk of this veterinary medicine.

Smoking and Genetic Variation in Metabolism of Environmental Chemicals: A Model for Environmental Reproductive Toxicology.

Smoking and Genetic Variation in Metabolism of Environmental Chemicals: A Model for Environmental Reproductive Toxicology.

Impact of Metal Nanoparticles on Germ Cell Viability and Functionality

Metal nanoparticles play an increasing role in consumer products, biomedical applications and in the work environment. Therefore, the effects of nanomaterials need to be properly understood. This applies especially to their potential reproductive toxicology (nanoreprotoxicity), because any shortcomings in this regard would be reflected into the next generation. This review is an attempt to summarize the current knowledge regarding the effects of nanoparticles on reproductive outcomes. A comprehensive collection of significant experimental nanoreprotoxicity data is presented, which highlight how the toxic effect of nanoparticles can be influenced, not only by the particles' chemical composition, but also by particle size, surface modification, charge and to a considerable extent on the experimental set-up. The period around conception is characterized by considerable cytological and molecular restructuring and is therefore particularly sensitive to disturbances. Nanoparticles are able to penetrate through biological barriers into reproductive tissue and at least can have an impact on sperm vitality and function as well as embryo development. Particularly, further investigations are urgently needed on the repetitively shown effect of the ubiquitously used titanium dioxide nanoparticles on the development of the nervous system. It is recommended that future research focuses more on the exact mechanism behind the observed effects, because such information would facilitate the production of nanoparticles with increased biocompatibility.

Reproductive toxicology of nickel – Review

The goal of this minireview is to summarize our current knowledge on the reproductive toxicity of soluble nickel salts. We made an attempt to present the most relevant data obtained from in vivo and in vitro experiments performed on mammals, mammalian primary cell cultures and cell lines. Nickel has been demonstrated to disturb the mammalian reproductive functions at several levels of regulation. The results of previous investigations indicate that the hormonal effects may play an important role in the reproductive toxicology of nickel both at the neuroendocrine and gonadal levels in the hypothalamic-pituitary-gonadal (HPG) axis. At the molecular level, it may be important that nickel may substitute certain other metals in metal dependent enzymes, leading to an altered protein function. It readily crosses the cell membrane via calcium channels and competes with calcium for specific receptors. Nickel can cross-link aminoacids to DNA, lead to formation of reactive oxygen species (ROS), moreover mimic hypoxia. These changes may lead to the activation of some signaling pathways, subsequent transcription factors and eventually to alterations in gene expression and cellular metabolism. These events are likely to be involved in the reproductive toxicity of nickel.

Book Review: Reproductive and Developmental Toxicology

Book Review: Reproductive and Developmental Toxicology

The bovine oocyte in vitro maturation model: A potential tool for reproductive toxicology screening

Reproductive toxicity testing according to the present guidelines requires a high number of animals. Therefore, the development of alternative in vitro methods is urgently required. The aim of the present study was to investigate the applicability domain of the bovine oocyte in vitro maturation assay (bIVM) to study female reproductive toxicology. Therefore, bovine oocytes were exposed to a broad set of chemicals of two distinct biological function groups: (a) affecting female fertility and (b) affecting embryonic development and having a broad range of physical and chemical properties. The endpoints evaluated were the oocyte nuclear maturation (progression of meiosis) and general cytotoxicity. The oocyte nuclear maturation was negatively affected by all compounds tested and the effect was observed at concentrations lower than the cytotoxic ones. The bIVM assay correctly predicted the classification of compounds between those predefined groups. Additionally, the bIVM model contributes significantly for the 3R principle, since no test animals are used in this assay. In conclusion, the bIVM is a sensitive and valuable alternative assay to identify potential chemical hazard on female fertility.