Endocrine-disrupting chemicals: elucidating our understanding of their role in sex and gender-relevant end points

Early-life exposure to acephate inhibits sexual development and induces testicular and ovarian toxicity in mice

Acephate is an organophosphate insecticide that exerts its toxicity by acting on the nervous system of insects. In addition to its action on the mammalian nervous system, acephate can also induce endocrine disruption of the reproductive system in mammals. However, the effects of acephate on sexual maturation and ovary development remain unclear. This study evaluated whether early-life exposure to acephate negatively impacts the male and female sexual maturation process and mature reproductive tissues. C57BL/6N mice were exposed to acephate (0, 0.3, 300 ppm) in drinking water from embryonic day 11.5 to ablactation, when the pups were four weeks old. Both sexes in the high-dose group experienced an early postnatal growth deficit, while females in the low-dose group continued to gain weight until 10 weeks of age. Exposure to acephate altered the anogenital index in females. Furthermore, preputial separation and vaginal opening were delayed in the high-dose group. At maturity, the weight of the seminal vesicles was decreased in the high-dose group. All treated groups exhibited increased vacuolation, accumulation of residual bodies, and degeneration in the testes. Furthermore, follicle regression was observed, and the healthy follicle number at each developmental stage was decreased in all treated groups. These results are probably due to the inhibition of the regulation by the hypothalamic-pituitary-gonadal axis and direct toxicity to reproductive organs. In conclusion, our study demonstrates that early-life exposure to acephate in mice may disrupt normal postnatal development, postpone puberty onset, and adversely affect reproductive functions during the reproductive period in both sexes.

Endocrine-disrupting chemicals and their effects on puberty

Sexual maturation in humans is characterized by a unique individual variability. Pubertal onset is a highly heritable polygenic trait but it is also affected by environmental factors such as obesity or endocrine disrupting chemicals. The last 30 years have been marked by a constant secular trend toward earlier age at onset of puberty in girls and boys around the world. More recent data, although more disputed, suggest an increased incidence in idiopathic central precocious puberty. Such trends point to a role for environmental factors in pubertal changes. Animal data suggest that the GnRH-neuronal network is highly sensitive to endocrine disruption during development. This review focuses on the most recent data regarding secular trend in pubertal timing as well as potential new epigenetic mechanisms explaining the developmental and transgenerational effects of endocrine disrupting chemicals on pubertal timing.

Postnatal BPA is associated with increasing executive function difficulties in preschool children

BACKGROUND

Early bisphenol exposure may have consequences for executive function development, but less is known about potential sex effects. We hypothesized that early bisphenol A (BPA) and bisphenol S (BPS) exposures would be associated with sex-dependent changes in preschool executive function.

METHODS

A subsample of the Alberta Pregnancy Outcomes and Nutrition (APrON) cohort (n = 312) provided maternal second trimester (prenatal) and 3-month postpartum (postnatal) urine samples, from which BPA and BPS concentrations were quantified. When children were age 2 and 4, mothers completed the Behavior Rating Inventory of Executive Function-Preschool Version (BRIEF-P). Changes in standardized T scores on the BRIEF-P indexes of inhibitory self-control, flexibility, and emergent metacognition were investigated.

RESULTS

Adjusted multivariate regression analyses showed that child sex modified the associations between maternal postnatal BPA and changes in executive function. Higher maternal postnatal BPA concentrations predicted increasing difficulties from age 2 to 4 in the domains of inhibitory self-control and emergent metacognition in female, but not male children. The other bisphenol concentrations were not associated with changes in executive function.

CONCLUSION

Due to the ubiquity of BPA exposure among breastfeeding women, these findings justify further investigation on the effects of postnatal bisphenol exposure on child cognitive development.

IMPACT

Higher concentrations of maternal BPA at 3-month postpartum were associated with increasing difficulties in inhibitory self-control and emergent metacognition from age 2 to 4 in girls, but not boys. Prenatal BPA and prenatal/postnatal BPS were not significant predictors of changes in executive function in boys and girls. The current study extends previous research to show that maternal postnatal BPA could also impact child executive function. Due to the ubiquity of BPA exposure among breastfeeding women, the current findings suggest that additional precautions may be needed to protect infants' neurodevelopment from indirect exposure to BPA.

Advances in Knowledge of Androgens: How Intentional and Accidental Neurosteroid Changes Inform Us of Their Action and Role

Purpose of Review

Here, we summarize current knowledge of androgens’ action gained over the recent years.

Recent Findings

Neurosteroids are produced in the brain and peripheral nerves, independent of endocrine glands have been investigated for how they are regulated, and have actions via non-steroid receptor targets to mediate social, affective, and cognitive behavior and to protect the brain. Androgens’ organizing actions in the peri-natal period have effects throughout the lifetime that may be recapitulated later in life during critical periods and at times of challenge. Developmental changes in androgens occur during mid-childhood, adrenarche, puberty, adolescence, young adulthood, middle age, and andropause. Changes in androgens with a 5α-reductase inhibitor, such as finasteride, result in disruptions in organizational and activational functions of androgens that can be unremitting.

Summary

Normal developmental or perturbation in androgens through other means can cause changes in androgen-sensitive phenotypes throughout the lifespan, in part through actions of neurosteroids.

Interleukin-4 signalling pathway underlies the anxiolytic effect induced by 3-deoxyadenosine

RATIONALE

Converging evidence suggests that neuroimmunity plays an important role in the pathophysiology of anxiety. Interleukin (IL)-4 is a key cytokine regulating neuroimmune functions in the central nervous system. More efficient anxiolytics with neuro-immune mechanisms are urgently needed.

OBJECTIVE

To determine whether 3'-deoxyadenosine (3'-dA) exerts an anxiolytic effect and to examine the role of IL-4 in the anxiolytic effect of 3'-dA in mice.

METHODS

We investigated the effects of 3'-dA on anxiety-like behaviors using elevated plus maze (EPM) or light-dark box (LDB) tests after 45 min or 5 days of treatment. Expression of IL-4, IL-10, IL-1β, TNF-α, and IL-6 in the prefrontal cortex (PFC) was detected by Western blot and/or double immunostaining. Intracerebroventricular injection of RIL-4Rα (an IL-4-specific inhibitor) and intraperitoneal injection of 3'-dA or imipramine were co-administered, followed by EPM test.

RESULTS

3'-dA exhibited a stronger and faster anxiolytic effect than imipramine in behavioral tests. Furthermore, 3'-dA enhanced IL-4 expression after 45 min or 5 days, TNF-α and IL-1β expression decreased significantly after a 5-day treatment with 3'-dA, and IL-10 expression increased after a 5-day treatment with 3'-dA or imipramine in the PFC. IL-4 was expressed in neurons and in some astrocytes and microglia. IL-4 expression showed a strong positive correlation with reduced anxiety behaviors. RIL-4Rα completely blocked the anxiolytic effects induced by 3'-dA and imipramine.

CONCLUSIONS

This study identifies a novel and common anxiolytic IL-4 signaling pathway and provides an innovative drug with a novel neuro-immune mechanism for treating anxiety disorder.

Post-finasteride syndrome and post-SSRI sexual dysfunction: two sides of the same coin?

Sexual dysfunction is a clinical condition due to different causes including the iatrogenic origin. For instance, it is well known that sexual dysfunction may occur in patients treated with antidepressants like selective serotonin reuptake inhibitors (SSRI). A similar side effect has been also reported during treatment with finasteride, an inhibitor of the enzyme 5alpha-reductase, for androgenetic alopecia. Interestingly, sexual dysfunction persists in both cases after drug discontinuation. These conditions have been named post-SSRI sexual dysfunction (PSSD) and post-finasteride syndrome (PFS). In particular, feeling of a lack of connection between the brain and penis, loss of libido and sex drive, difficulty in achieving an erection and genital paresthesia have been reported by patients of both conditions. It is interesting to note that the incidence of these diseases is probably so far underestimated and their etiopathogenesis is not sufficiently explored. To this aim, the present review will report the state of art of these two different pathologies and discuss, on the basis of the role exerted by three different neuromodulators such as dopamine, serotonin and neuroactive steroids, whether the persistent sexual dysfunction observed could be determined by common mechanisms.

Benzophenone-type UV filters in surface waters: An assessment of profiles and ecological risks in Shanghai, China

Benzophenone-type UV filters (BP-UV filters) are frequently introduced into aquatic environment from several sources. The occurrence and fate of select BP-UV filters and their metabolites were investigated in this study. All target compounds were detected in water samples, except for 2, 3, 4-trihydroxybenzophenone (2, 3, 4-OH-BP). The concentration reached up 131ngL^-1 for 5-benzoyl-4-hydroxy-2-ethoxybenzenesulfonic acid (BP-4), 30.0ngL^-1 for 2-hydroxy-4-methoxybenzophenone (BP-3), and mean value of 158ngL^-1 for benzophenone (BP). Concentrations of BP-UV filters were not related to recreational waters but with high population frequencies. In addition, five BP-UV filters, namely 2,2',4,4'-tetrahydroxybenzophenone (BP-2), 2,3,4-OH-BP, 2,4-dihydroxybenzophenone (BP-1), 4-hydroxybenzophenone (4-OH-BP) and BP were investigated for probable sources, and found that they originate from BP-3 metabolism. There is a similar source for BP-3, BP-4, BP-1, 4-OH-BP and BP. Environmental risk assessment (ERA) showed that risk quotients (RQs) of BP-4, BP-3 and BP were 2.7, 0.8 and 0.5, respectively.

Impact of endocrine disrupting chemicals on onset and development of female reproductive disorders and hormone-related cancer

A growing body of evidence suggests that exposure to chemical substances designated as endocrine disrupting chemicals (EDCs) due to their ability to disturb endocrine (hormonal) activity in humans and animals, may contribute to problems with fertility, pregnancy, and other aspects of reproduction. The presence of EDCs has already been associated with reproductive malfunction in wildlife species, but it remains difficult to prove causal relationships between the presence of EDCs and specific reproductive problems in vivo, especially in females. On the other hand, the increasing number of experiments with laboratory animals and in vitro research indicate the ability of different EDCs to influence the normal function of female reproductive system, and even their association with cancer development or progression. Research shows that EDCs may pose the greatest risk during prenatal and early postnatal development when organ and neural systems are forming. In this review article, we aim to point out a possible contribution of EDCs to the onset and development of female reproductive disorders and endocrine-related cancers with regard to the period of exposure to EDCs and affected endpoints (organs or processes).

Endocrine Disruption in the Omics Era: New Views, New Hazards, New Approaches

The genome revolution has brought about a complete change on our view of biological systems. The quantitative determination of changes in all the major molecular components of the living cells, the "omics" approach, opened whole new fields for all health sciences, including toxicology. Endocrine disruption,i.e., the capacity of anthropogenic pollutants to alter the hormonal balance of the organisms, is one of the fields of Ecotoxicology in which omics has a relevant role. In the first place, the discovery of scores of potential targets in the genome of almost any Metazoan species studied so far, each of them being a putative candidate for interaction with endocrine disruptors. In addition, the understanding that ligands, receptors, and their physiological functions suffered fundamental variations during animal evolution makes it necessary to assess disruption effects separately for each major taxon. Fortunately, the same deal of knowledge on genes and genomes powered the development of new high-throughput techniques and holistic approaches. Genomics, transcriptomics, proteomics, metabolomics, and others, together with appropriate prediction and modeling tools, will mark the future of endocrine disruption assessment both for wildlife and humans.

Effects of environmental endocrine disruptors, including insecticides used for malaria vector control on reproductive parameters of male rats

The male reproductive system is sensitive to endocrine disrupting chemicals (EDCs) during critical developmental windows. Male Sprague-Dawley rats were exposed in utero-, during lactation- and directly to 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT), 1,1,-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE) and a mixture of DDT, deltamethrin (DM), p-nonylphenol (p-NP) and phytoestrogens, at concentrations found in a malaria-area. After dosing for 104 days, histological assessments and reproductive-endpoints were assessed. The anogenital distance (AGD) (P=0.005) was shorter in the mixture-exposed group, while the prostate mass (P=0.018) was higher in the DDT-exposed group. A higher testicular mass and abnormal histology was observed in the DDT-(P=0.019), DDE-(P=0.047) and mixture-exposed (P<0.005) groups. This study shows that in utero-, lactational- and direct exposure to EDCs present in a malaria-area negatively affects male reproductive parameters in rats. These findings raise concerns to EDC-exposures to mothers living in malaria-areas and the reproductive health of their male offspring.

The effects of prenatal PCBs on adult social behavior in rats

Endocrine disrupting chemical (EDC) exposures during critical periods of development may influence neuronal development and the manifestation of sexually dimorphic sociability and social novelty behaviors in adulthood. In this study, we assessed the effects of gestational exposure to PCBs on the social behavior of males and females later in adulthood. A weakly estrogenic PCB mixture, Aroclor 1221 (A1221, 0.5 or 1mg/kg) was administered to pregnant Sprague-Dawley rat dams. Both a positive control (estradiol benzoate; EB, 50μg/kg) and negative control (dimethylsulfoxide; DMSO in sesame oil vehicle) were similarly administered to separate sets of dams. The sexes responded differently in two tasks essential to sociality. Using a three-chamber apparatus that contained a caged, same-sex, gonadectomized stimulus animal and an empty stimulus cage, we found that both sexes showed a strong preference for affiliating with a stimulus animal (vs. an empty cage), an effect that was much more pronounced in the males. In the second task, a novel and a familiar stimulus animal were caged at opposite ends of the same apparatus. Females displayed a higher degree of novelty preference than the males. During both tests, females had significantly higher social approach behaviors while male engaged in significantly more interactive behaviors with the conspecific. Of particular interest, males born of dams that received prenatal A1221 (0.5mg/kg) exhibited an overall decrease in nose-to-nose investigations. These behavioral data suggest that the males are more sensitive to A1221 treatment than are females. In addition to behavioral analysis, serum corticosterone was measured. Females born of dams treated with A1221 (0.5mg/kg) had significantly higher concentrations of corticosterone than the DMSO female group; males were unaffected. Females also had significantly higher corticosterone concentrations than did males. Overall, our results suggest that the effects of gestational exposure to PCBs on adult social behavior are relatively limited within this particular paradigm.