Changes in male reproductive health and effects of endocrine disruptors in Scandinavian countries

Decreased sperm motility in rats orally exposed to single or mixed pesticides

The Brazilian Agency of Sanitary Vigilance (ANVISA) conducted a study that demonstrated the presence of residues of several pesticides in fresh fruits and vegetables that were available for purchase by the general populace. In order to evaluate potential adverse health effects of low-level exposure to agrochemicals, the reproductive toxicity of the pesticides dicofol, dichlorvos, permethrin, endosulfan, and dieldrin was evaluated in rats dosed with these chemicals individually or as mixtures. Sixty male Lewis rats (6 wk old, 200 x g) were randomly allocated to 8 groups: (1) control group, received basal diet; (2) 5 groups designated a to e received the diet containing each pesticide individually, at the respective effective doses: lowest-observed-adverse-effect level (LOAEL) for dieldrin and endosulfan, lowest-observed-effect level (LOEL) for dicofol, and lowest effect level (LEL) for dichlorvos and permethrin, respectively, depending on the published data; (3) effective dose group, which received a mixture of pesticides added to basal diet at the respective doses reported to produce adverse effects; and (4) low dose group, which received a pesticide mixture added to the basal diet, where each pesticide was at its no-observed-effect level (NOEL). After 8 wk of treatment, reproductive parameters were evaluated. Sperm morphology, daily sperm production (DSP), sperm transit time through the epididymis, hormonal levels, and histopathological evaluation of testis and epididymis did not differ significantly among the groups. However, sperm motility was significantly decreased in animals that received a mixture of dieldrin, endosulfan, dicofol, dichlorvos, and permethrin, as well as in the group receiving dicofol alone. Exposure to the individual pesticides endosulfan, dichlorvos, and permethrin did not markedly affect sperm motility. The impairment of sperm motility in the mixture of pesticides at the NOEL level indicates that reproductive effects not seen with individual pesticides may occur in presence of several pesticides due to an additive effect. However, the pesticide mixtures did not appear to affect DSP or spermatogenesis despite reduced sperm motility.

Evidence of an environmental contribution to the aetiology of cryptorchidism and hypospadias?

OBJECTIVES

Evidence suggests that there is geographical variation in the birth prevalence of both cryptorchidism and hypospadias. The aim was to determine if there is evidence of spatial heterogeneity in the prevalence of these conditions and to test the hypothesis that environmental factors may contribute to aetiology.

METHODS

A population-based dataset of cryptorchidism and hypospadias cases was constructed from the hospital episodes statistics that covered the Northern Region of England and assigned to a small area based on the residential address at time of admission. Expected numbers of cases for each small area were computed. The ratio of observed to expected cases was determined for each small area and analysed with respect to both geographical heterogeneity and small area level socio-economic deprivation. The Potthoff-Whittinghill method was used to determine if there was localized spatial clustering of cases.

RESULTS

There was statistically significant spatial clustering for cases of both cryptorchidism [estimated Extra-Poisson Variation (EPV) = 0.14; 95% CI, 0.03-0.25] and hypospadias (EPV = 0.17; 95% CI, 0.05-0.28). In addition, increased prevalence was associated with lower levels of deprivation for hypospadias (P = 0.06), but there was no such relationship for cryptorchidism (P = 0.61).

CONCLUSIONS

The finding of localized spatial heterogeneity in the prevalence of cryptorchidism and hypospadias is consistent with the involvement of a spatially varying environmental risk factor. The apparent social patterning of hypospadias is likely to reflect an association with lifestyle and other factors which underpin social variation in health. However, there also remains a possibility that these findings may be due to variability in ascertainment of cases.

Species-specific testicular and hepatic microsomal metabolism of benzo(a)pyrene, an ubiquitous toxicant and endocrine disruptor

Information on the metabolism of the environmental toxicant, benzo(a)pyrene (BaP) in the male reproductive system is crucial for understanding BaP-induced infertility. Microsomes were isolated from the liver and testes of rat, mouse, hamster, ram, boar, bull, and monkey and incubated with BaP. Post-incubation, samples were extracted with ethyl acetate and analyzed for BaP/metabolites by reverse-phase HPLC with fluorescence detection. A great variation among species to metabolize BaP was observed. The rodent testicular microsomes produced higher proportions of BaP 4,5-diol and 9,10-diol than did boar, ram, bull, and monkey. On the other hand, hepatic microsomes from higher mammals converted a greater proportion of BaP to 3-hydroxy and 9-hydroxy BaP, the detoxification products of BaP. Given the ability of BaP 7-8-diol 9, 10-epoxide, 3-, and 9-hydroxy BaP to bind with DNA and form adducts, there is a likelihood of risk arising from the accumulation of BaP metabolites in testicular tissues. These metabolites may interfere with the formation and function of gametes, eventually contributing to infertility.

Mechanisms of action underlying the antiandrogenic effects of the fungicide prochloraz

The fungicide prochloraz has got multiple mechanisms of action that may influence the demasculinizing and reproductive toxic effects of the compound. In the present study, Wistar rats were dosed perinatally with prochloraz (50 and 150 mg/kg/day) from gestational day (GD) 7 to postnatal day (PND) 16. Caesarian sections were performed on selected dams at GD 21, while others were allowed to give birth to pups that were followed until PND 16. Prochloraz caused mild dysgenesis of the male external genitalia as well as reduced anogenital distance and retention of nipples in male pups. An increased anogenital distance indicated virilization of female pups. Effects on steroidogenesis in male fetuses became evident as decreased testicular and plasma levels of testosterone and increased levels of progesterone. Ex vivo synthesis of both steroid hormones was qualitatively similarly affected by prochloraz. Immunohistochemistry of fetal testes showed increased expression of 17alpha-hydroxylase/17,20-lyase (P450c17) and a reduction in 17beta-hydroxysteroid dehydrogenase (type 10) expression, whereas no changes in expression of genes involved in testicular steroidogenesis were observed. Increased expression of P450c17 mRNA was observed in fetal male adrenals, and the androgen-regulated genes ornithine decarboxylase, prostatic binding protein C3 as well as insulin-like growth factor I mRNA were reduced in ventral prostates PND 16. These results indicate that reduced activity of P450c17 may be a primary cause of the disrupted fetal steroidogenesis and that an altered androgen metabolism may play a role as well. In vitro studies on human adrenocortical carcinoma cells supported the findings in vivo as reduced testosterone and increased progesterone levels were observed. Overall, these results together indicate that prochloraz acts directly on the fetal testis to inhibit steroidogenesis and that this effect is exhibited at protein, and not at genomic, level.

Occurrence of estrogen-like substances in the marine environment of the Northern Mediterranean Sea

Evidence has been presented that a number of environmental agents perturbs the function of the sex hormone signalling pathways in marine animals. In this work the estrogenic/antiestrogenic activity of coastal marine water samples from five sites of the Northern Mediterranean Sea was assayed using a recombinant Saccharomyces cerevisiae yeast strain (RMY326 ER-ERE) transfected with the human estrogen receptor alpha. Extraction of potential EDCs from seawater was performed in columns packed with XAD-2 resins. The estrogenic activity was calculated as percentage of the activity of 17beta-estradiol (10 nM) and it ranged from 4.8% and 59.03%, significantly depending on sampling site (p=0.0013) and season (p<0.05). Antagonistic activity of extracts was also detected and the percentage of inhibition of estradiol-dependent beta-galactosidase induction ranged to 52.8%. These results point the reliability of the yeast assay as a first level screening test to assess the quality of aquatic environments.

Development of the mammalian urethra is controlled by Fgfr2-IIIb

Development of external genitalia in mammalian embryos requires tight coordination of a complex series of morphogenetic events involving outgrowth,proximodistal and dorsoventral patterning, and epithelial tubulogenesis. Hypospadias is a congenital defect of the external genitalia that results from failure of urethral tube closure. Although this is the second most common birth defect in humans, affecting one in every 250 children, the molecular mechanisms that regulate morphogenesis of the mammalian urethra are poorly understood. We report that mice lacking the IIIb isoform of fibroblast growth factor receptor 2 (Fgfr2) exhibit severe hypospadias. Urethral signaling regions, as indicated by Shh and Fgf8 expression, are established in Fgfr2-IIIb null mice; however, cell proliferation arrests prematurely and maturation of the urethral epithelium is disrupted. Fgfr2-IIIb-/- mutants fail to maintain the progenitor cell population required for uroepithelial renewal during tubular morphogenesis. In addition, we show that antagonism of the androgen receptor (AR) leads to loss of Fgfr2-IIIb and Fgf10 expression in the urethra, and an associated hypospadias phenotype, suggesting that these genes are downstream targets of AR during external genital development. Genitourinary defects resulting from disruption of AR activity, by either genetic or environmental factors, may therefore involve negative regulation of the Fgfr2 pathway. This represents the first example of how the developing genitourinary system integrates cues from systemically circulating steroid hormones with a locally expressed growth factor pathway.