Investigations of putative reproductive toxicity of low-dose exposures to vinclozolin in Wistar rats

Effect of Pesticide Vinclozolin Toxicity Exposure on Cardiac Oxidative Stress and Myocardial Damage

(1) Background: Vinclozolin is a popular fungicide used in fruit, ornamental plants, and vegetable crops. It has recently been seen that prolonged exposure to VZN can cause human or animal health damage to various organs, but little is known to date about its cardiovascular effects. In this study, we addressed the chronic effects of VZN on the myocardium and the enzymes involved in the cardiovascular function. (2) Methods: The animals were divided into four groups: group 1 served as the control, group 2 received 1 mg/kg of VZN by gavage, group 3 received 30 mg/kg of VZN by gavage, and group 4 received 100 mg/kg of VZN by gavage, for 30 days. (3) Results: Results showed that 100 mg/kg VZN markedly increased the plasma concentration of cardiac markers (CK-MB, cTnT, ANP, BNP). Moreover, compared to the control group, VZN treatment decreased the activity of SOD, CAT, and GPx, and downregulated the mRNA expression levels of Nrf2. Furthermore, collagen deposition was amplified owing to 100 mg/kg VZN cardiotoxicity. This harmful effect was confirmed by a histological study using hematoxylin and eosin (H&E) and Masson's trichrome staining. (4) Conclusion: Overall, our results proved the cardiotoxicity caused by chronic exposure to VZN.

Effects of chronic exposure to the fungicide vinclozolin on gut microbiota community in an aquatic turtle

Environmental issues associated with the widespread use of agricultural chemicals are being seriously concerned. Of them, toxicological impacts of fungicides in aquatic organisms are often overlooked. Here, soft-shelled turtle (Pelodiscus sinensis) hatchlings were exposed to different concentrations of vinclozolin (0, 5, 50, 500 and 5000 μg/L) for 60 days to investigate the impact of fungicide exposure on their gut microbial composition and diversity. Vinclozolin exposure significantly affected the composition of the gut microbiota in hatchling turtles. Unexpectedly, gut bacterial diversity and richness of vinclozolin-exposed turtles (but not for the 5000 μg/L-exposed group) were relatively higher than control ones. At the phylum level, the abundance of Firmicutes was decreased, while that of Proteobacteria was increased in high-concentration groups. At the genus level, some bacterial genera including Cellulosilyticum, Romboutsia and Clostridium_sensu_stricto, were significantly changed after vinclozolin exposure; and some uniquely observed in high-concentration groups. Gene function predictions showed that genes related to amino acid metabolism were less abundant, while those related to energy metabolism more abundant in high-concentration groups. The prevalence of some pathogens inevitably affected gut health status of vinclozolin-exposed turtles. Such gut microbiota dysbiosis might be potentially linked with hepatic metabolite changes induced by vinclozolin exposure.

Functional and hepatic metabolite changes in aquatic turtle hatchlings exposed to the anti-androgenic fungicide vinclozolin

Many man-made chemicals that are released into water bodies in agricultural landscapes have been identified as endocrine disruptors and can cause serious impacts on the growth and survival of aquatic species living in these environments. However, very little attention has been paid to their toxicological effects in cultured non-fish species, such as aquatic turtles. We exposed hatchlings of the Chinese soft-shelled turtle (Pelodiscus sinensis) to different concentrations of vinclozolin (0, 5, 50 and 500 μg/L) for 60 days to assess physiological and metabolic impacts of this fungicide. Despite no death occurrence, hatchling turtles exposed to the highest concentration of vinclozolin consumed less food, grew more slowly (resulting in smaller body size after exposure) and performed more poorly in behavioral swimming tests than controls and turtles exposed to lower concentrations. Hepatic metabolite profiles acquired via liquid chromatography-mass spectrometry (LC-MS) revealed multiple metabolic perturbations related to amino acid, lipid, and fatty acid metabolism in animals exposed to environmentally relevant concentrations. Specifically, many critical metabolites involved in energy-related metabolic pathways (such as some intermediates in the tricarboxylic acid cycle, lactate, and some amino acids) were present in livers of hatchling turtles exposed vinclozolin, though at lower concentrations, reflecting energy metabolism dysregulation induced by exposure to this fungicide. Overall, our results suggest that the changes in growth and behavioral performances caused by chronic vinclozolin exposure may be associated with internal physiological and metabolic disorders mediated at the biochemical level.

Endocrine disruptor chemicals. A review of their effects on male reproduction and antioxidants as a strategy to counter it

Endocrine disruptor chemicals are exogenous molecules that generate adverse effects on human health by destabilizing the homeostasis of endocrine system and affecting directly human reproductive system by inhibiting or activating oestrogenic or androgenic receptors. Endocrine disruptor chemicals generate transgenerational epigenetic problems, besides being associated with male infertility. Epidemiological data indicate that the increase in reproductive problems in males in the last 50 years is correlated with the increase of endocrine disrupting chemicals in the environment, being associated with a decrease in semen quality and direct effects on spermatozoa, such as alterations in motility, viability and acrosomal reaction, due to the generation of oxidative stress, and have also been postulated as a possible cause of testicular dysgenesis syndrome. Diverse antioxidants, such as C and E vitamins, N-acetylcysteine, selenium and natural vegetable extracts, are among the alternatives under study to counter the effects of endocrine disruptor chemicals. In some cases, the usage of them has given positive results and the opposite in others. In this review, we summarize the recent information about the effects of endocrine disruptor chemicals on male reproduction, on sperm cells, and the results of studies that have tested antioxidants as a strategy to diminish their harmful effects.

A mixture of 15 phthalates and pesticides below individual chemical no observed adverse effect levels (NOAELs) produces reproductive tract malformations in the male rat

Humans carry residues of multiple synthetic chemicals at any given point in time. Research has demonstrated that compounds with varying molecular initiating events (MIE) that disrupt common key events can act in concert to produce cumulative adverse effects. Congenital defects of the male reproductive tract are some of the most frequently diagnosed malformations in humans and chemical exposures in utero can produce these effects in laboratory animals and humans. Here, we hypothesized that in utero exposure to a mixture of pesticides and phthalates, each of which produce male reproductive tract defects individually, would produce cumulative effects even when each chemical is present at a no observed adverse effect level (NOAEL) specific for male reproductive effects. Pregnant Sprague-Dawley rats were exposed via oral gavage to a fixed-ratio dilution mixture of 5 pesticides (vinclozolin, linuron, procymidone, prochloraz, pyrifluquinazon), 1 pesticide metabolite (dichlorodiphenyldichloroethylene (DDE)), and 9 phthalates (dipentyl, dicyclohexyl, di-2-ethylhexyl, dibutyl, benzyl butyl, diisobutyl, diisoheptyl, dihexyl, and diheptyl) during the critical window of rat fetal masculinization (gestation day 14-18). The top dose (100% dose) contained each compound at a concentration 2-fold greater than the individual chemical NOAEL followed by a dilution series that represented each chemical at NOAEL, NOAEL/2, NOAEL/4, NOAEL/8, NOAEL/15, NOAEL/100, NOAEL/1000. Reduced fetal testis gene expression occurred at NOAEL/15, reduced fetal testis testosterone production occurred at NOAEL/8, reduced anogenital distance, increased nipple retention, and delayed puberty occurred at NOAEL/4, and severe effects including genital malformations and weight reductions in numerous reproductive tissues occurred at NOAEL/2. This study demonstrates that these phthalates and pesticides acted cumulatively to produce adverse effects at doses below which any individual chemical had been shown to produce an effect alone and even though they have different MIEs.

On the Use and Interpretation of Areola/Nipple Retention as a Biomarker for Anti-androgenic Effects in Rat Toxicity Studies

Areola/nipple retention (NR) is an established biomarker for an anti-androgenic mode of action in rat toxicity studies. It is a mandatory measurement under several OECD test guidelines and is typically assessed in combination with anogenital distance (AGD). Both NR and AGD are considered retrospective biomarkers of insufficient androgen signaling during the masculinization programming window in male fetuses. However, there are still aspects concerning NR as a biomarker for endocrine disruption that remains to be clarified. For instance, can NR be regarded a permanent adverse effect? Is it a redundant measurement if AGD is assessed in the same study? Is NR equally sensitive and specific to anti-androgenic chemical substances as a shortening of male AGD? In this review we discuss these and other aspects concerning the use of NR as a biomarker in toxicity studies. We have collected available literature from rat toxicity studies that have reported on NR and synthesized the data in order to draw a clearer picture about the sensitivity and specificity of NR as an effect biomarker for an anti-androgenic mode of action, including comparisons to AGD measurements. We carefully conclude that NR and AGD in rats for the most part display similar sensitivity and specificity, but that there are clear exceptions which support the continued assessment of both endpoints in relevant reproductive toxicity studies. Available literature also support the view that NR in infant male rats signifies a high risk for permanent nipples in adulthood. Finally, the literature suggests that the mechanisms of action leading from a chemical stressor event to either NR or short AGD in male offspring are overlapping with respect to canonical androgen signaling, yet differ with respect to other mechanisms of action.

Effects of the endocrine disruptor vinclozolin in male reproduction: a systematic review and meta-analysis†

Endocrine-disrupting chemicals have become an issue of scientific and public discussion. Vinclozolin (VNZ) is a fungicide that competitively antagonizes the binding of natural androgens to their receptor, disturbing the function of tissues that are sensitive to these hormones, as is the case of the male reproductive organs. A systematic review with meta-analyses of rodent studies was conducted to answer the following question: Does exposure to VNZ affect sperm parameters and testicular/epididymal weight? The methodology was prespecified according to the Cochrane Handbook for Systematic Reviews and PRISMA recommendations. Sixteen articles met the inclusion criteria, comprising a total of 1189 animals. The risk of publication bias was assessed using the Trim and Fill adjustment, funnel plot, and Egger regression test. Heterogeneity and inconsistency across the findings were tested using the Q-statistic and I2 of Higgins, respectively. Sensitivity was also analyzed. Statistical analysis was performed on Comprehensive Meta-Analysis software (Version 2.0), using random models and weighted mean differences along with a 95% confidence interval. Sperm motility, counts, daily sperm production (evidence of publication bias), and epididymis weight were decreased in VNZ-treated animals. Exposure length and dose, as well as the time point of exposure, influenced the obtained results. Despite the moderate/high heterogeneity observed, the sensitivity analysis overall demonstrated the robustness of the findings. The quality scores of the included studies were superior to 4 in a total of 9, then classified as good. The obtained data corroborate the capability of VNZ exposure to disrupt spermatogenic output and compromise male fertility.

Different exposure windows to low doses of genistein and/or vinclozolin result in contrasted disorders of testis function and gene expression of exposed rats and their unexposed progeny

Living species including humans are continuously exposed to low levels of a myriad of endocrine active compounds that may affect their reproductive function. In contrast, experimental designs scrutinizing this question mostly consider the gestational/lactational period, select high unrealistic doses and, have rarely investigated the possible reproductive consequences in the progeny. The present study aimed at assessing comparatively a set of male reproductive endpoints according to exposure windows, gestational/lactational versus pre-pubertal to adulthood, using low doses of endocrine active substances in male rats as well as their unexposed male progeny. Animals were orally exposed to 1 mg/kg bw/d of genistein and/or vinclozolin, from conception to weaning or from prepuberty to young adulthood. A number of reproductive endpoints were assessed as well as testicular mRNA expression profiles, in the exposed rats and their unexposed progeny. Overall, the low dosage used only affected weakly most of classical reproductive endpoints. However, the gestational/lactational exposure to vinclozolin alone or combined to genistein significantly delayed the puberty onset. Contrasting with the gestational/lactational exposure, a decreased sperm production was found in the animals exposed to genistein and vinclozolin from the pre-pubertal period but also in their progeny for vinclozolin and the mixture. The expression level of several genes involved in meiosis, apoptosis and steroidogenesis was also affected differentially as a function of the exposure window in both exposed rats and unexposed offspring. We also provide further evidence that doses of endocrine active substances relevant with human exposure may affect the male reproductive phenotype and testicular transcriptome in the exposed generation as well as in the indirectly exposed offspring.

Cyanidin-3- O-glucoside at Low Doses Protected against 3-Chloro-1,2-propanediol Induced Testis Injury and Improved Spermatogenesis in Male Rats

In recent decades, the capability of mankind spermatogenesis is declining due to various threats. Anthocyanins as colorful polyphenols possess beneficial functions for the organisms, including Leydig cells, but their effects on male spermatogenesis remain underexplored. In our study, the protective effect of cyanidin-3- O-glucoside (C3G) was investigated on the 3-chloro-1,2-propanediol (3-MCPD) caused rat spermatogenic disorders. At low doses, C3G improved the number and motility of the sperms, alleviating the seminiferous tubule injury. Interestingly, C3G showed no influence on sexual hormone but increased the androgen receptor expression. Meanwhile, C3G reduced the oxidative stress and number of apoptotic cells and promoted the integrity of the blood-testis barrier in the testis. Additionally, C3G mediated the activation of p-ERK, p-JNK, and p53, which are related to the protection of Sertoli cells and spermatogenesis. In conclusion, C3G protected against the 3-MCPD caused testis damage and spermatogenic disorders under appropriate doses, which indicates the potential protection of anthocyanins on male reproduction.

Genotoxic effects of vinclozolin on the aquatic insect Chironomus riparius (Diptera, Chironomidae)

Vinclozolin (Vz) is a pollutant found in aquatic environments whose antiandrogenic effects in reproduction are well known in mammals. Although its reproductive effects have been less studied in invertebrates, other effects, including genotoxicity, have been described. Therefore, in this work, we studied the genotoxic effects of Vz in the freshwater benthic invertebrate Chironomus riparius. DNA damage was evaluated with the comet assay (tail area, olive moment, tail moment and % DNA in tail), and the transcriptional levels of different genes involved in DNA repair (ATM, NLK and XRCC1) and apoptosis (DECAY) were measured by RT-PCR. Fourth instar larvae of C. riparius, were exposed to Vz for 24 h at 20 and 200 μg/L. The Vz exposures affected the DNA integrity in this organism, since a dose-response relationship occurred, with DNA strand breaks significantly increased with increased dose for tail area, olive moment and tail moment parameters. Additionally, the lower concentration of Vz produced a significant induction of the transcripts of three genes under study (ATM, NLK and XRCC1) showing the activation of the cellular repair mechanism. In contrast, the expression of these genes with the highest concentration were downregulated, indicating failure of the cellular repair mechanism, which would explain the higher DNA damage. These data report for the first time the alterations of Vz on gene transcription of an insect and confirm the potential genotoxicity of this compound on freshwater invertebrates.

Investigations on the dose-response relationship of combined exposure to low doses of three anti-androgens in Wistar rats

The current investigation examines whether combined exposure to three anti-androgens (flutamide, prochloraz, vinclozolin) result in interference with endocrine homeostasis when applied at very low dose levels, and whether the results of combined exposure are more pronounced than to the individual compounds. A pre-post-natal in vivo study design was chosen with more parameters than regulatory testing protocols require (additional endpoints addressing hormone levels, morphology and histopathological examinations). Dose levels were chosen to represent the lowest observed adverse effect level (LOAEL), the no observed adverse effect level (NOAEL), and the acceptable daily intake for each individual substance. Anti-androgenic changes were observable at the effect level (LOAEL) but not at lower exposures. Nipple/areola counts appeared to be a sensitive measure of effect, in addition to male sex organ weights at sexual maturation, and finally gross findings. The results indicate the absence of evidence for effects at low or very low dose levels. No (adverse) effects were seen at the NOAEL dose. A non-monotonic dose-response relationship was not evident. Combined exposure at LOAEL level resulted in enhanced responses for anogenital index, number of areolas/nipples, delayed preputial separation and reduced ventral prostate weight in comparison to the individual compounds.