Environmental neurotoxic effects: the search for new protocols in functional teratology

PCBs levels and indicator congeners in children's and adolescents' hair

Thirty polychlorinated biphenyl (PCB) congeners were determined in the hair samples collected from children (4-12) and adolescents (13-18) of Changchun city, Northeastern China. The mean concentrations of total PCBs and dioxin-like PCBs (dl-PCBs) in the adolescents' hair samples were 161.0 ng g(-1) and 61.7 ng g(-1), which were relatively higher than 43.7 ng g(-1) and 14.6 ng g(-1) in the children's ones. Considering gender difference, the mean concentrations in the girls' hair samples were approximately two times higher than those in the boys' ones for most PCB congeners. The pentachlorinated biphenyl was the dominant homologue. It was found that the levels of total PCBs and dl-PCBs were highly correlated with PCB 118 level in the children's hair samples, and with PCB 114 level in the adolescents' ones. The result demonstrated that the two PCB congeners could be applied as the indicators to evaluate the concentrations of total PCBs and dl-PCBs in children's and adolescents' hair, respectively.

Sensitive detection of endocrine disrupters using ionic liquid--single walled carbon nanotubes modified screen-printed based biosensors

Simple and low cost biosensor based on screen-printed electrode for sensitive detection of some alkylphenols was developed, by entrapment of HRP in a nanocomposite gel based on single-walled carbon nanotubes (SWCNTs) and 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF(6)]) ionic liquid. Raman and FTIR spectroscopy, CV and EIS studies demonstrate the interaction between SWCNTs and ionic liquid. The nanocomposite gel, SWCNT-[BMIM][PF(6)] provides to the modified sensor a considerable enhanced electrocatalytic activity toward hydrogen peroxide reduction. The HRP based biosensor exhibits high sensitivity and good stability, allowing a detection of the alkylphenols at an applied potential of -0.2V vs. Ag/AgCl, in linear range from 5.5 to 97.7 μM for 4-t-octylphenol and respectively, between 5.5 and 140 μM for 4-n-nonylphenol, with a response time of about 5s. The detection limit was 1.1 μM for 4-t-octylphenol, and respectively 0.4 μM for 4-n-nonylphenol (S/N=3).

Potential toxicological hazard due to endocrine-disrupting chemicals on Mediterranean top predators: state of art, gender differences and methodological tools

Man-made endocrine-disrupting chemicals (EDCs) range across all continents and oceans. Some geographic areas are potentially more threatened than others: one of these is the Mediterranean Sea. Levels of some xenobiotics are much higher here than in other seas and oceans. In this paper we review the final results of a project supported by the Italian Ministry of the Environment, in which the hypothesis that Mediterranean top predator species (such as large pelagic fish and marine mammals) are potentially at risk due to EDCs was investigated. We illustrate the need to develop and apply sensitive methodological tools, such as biomarkers (Vitellogenin, Zona Radiata proteins and CYP1A activities) for evaluation of toxicological risk in large pelagic fish top predators (Swordfish, (Xiphias gladius), Bluefin Tuna (Thunnus thynnus thynnus)) and nondestructive biomarkers (CYP1A activities and fibroblast cell culture in skin biopsy), for the hazard assessment of threatened marine mammals species (Striped Dolphin, (Stenella coeruleoalba), Bottlenose Dolphin (Tursiops truncatus), Common Dolphin (Delphinus delphis) and Fin Whale (Balaenoptera physalus))exposed to EDCs. Differential gender susceptibility to EDCs is also explored both in large pelagic fish and in cetaceans. In cetaceans, male specimens showed higher cytochrome P450 induction (BPMO in skyn biopsies, CYP2B in fibroblasts cell cultures) by xenobiotics with respect to females.

Changes in Ca(2+)/calmodulin-dependent protein kinase II activity and its relation to performance in passive avoidance response and long-term potentiation formation in mice prenatally exposed to diethylstilbestrol

We investigated the effects of prenatal exposure to diethylstilbestrol (DES), an endocrine disrupter on learning behavior and synaptic functions. Specifically, we determined the activity of Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) and related kinases that play an essential role in long-term potentiation (LTP) in the hippocampus in mice that were prenatally exposed to DES. Treatment with DES resulted in increased CaMKII autophosphorylation and Ca(2+)-independent activity in the hippocampus and cortex of male mice. Impaired passive avoidance correlated with this increased CaMKII autophosphorylation, as did the enhanced early phase of LTP (E-LTP) in hippocampus. These data suggest that prenatal exposure to DES induces deficits in passive avoidance responses as a result of increased CaMKII activity and hippocampal LTP.

D-amphetamine-related reinforcing effects are reduced in mice exposed prenatally to estrogenic endocrine disruptors

Estrogenic endocrine disruptors are hormonally active compounds that can bind to estradiol receptors. Central dopamine pathways have been reported to be affected by early developmental exposure to estrogenic endocrine disruptors. In the present study, pregnant female CD-1 mice were allowed to drink spontaneously either oil or environmentally relevant low doses of two estrogenic compounds, methoxychlor (20 microg/kg) or bisphenol-A (10 microg/kg) during gestation days 11-18. Their adult offspring were assessed for conditioned place preference produced by D-amphetamine (0, 1 or 2 mg/kg). Interestingly, prenatal treatment effects were sex-dependent and no changes in conditioned place preference emerged for the male offspring. Conversely, a clear-cut profile of D-amphetamine-induced conditioned place preference was only shown by oil-exposed females, whereas exposure to bisphenol-A or methoxychlor resulted in little or no place conditioning. Locomotor effects of acute d-amphetamine were not affected by prenatal exposure to bisphenol-A or methoxychlor. As a whole, prenatal exposure to estrogenic endocrine disruptors affected some steps in the organization of the brain dopaminergic systems in the female offspring, thus leading to long-term alterations in neurobehavioral function. These data confirm that exposure to weak environmental estrogens in the period of brain sexual differentiation can influence adult behavior.

The use of a non-lethal tool for evaluating toxicological hazard of organochlorine contaminants in Mediterranean cetaceans: new data 10 years after the first paper published in MPB

In the Mediterranean Sea, top predators, and particularly cetacean odontocetes, accumulate high concentrations of organochlorine contaminants and toxic metals, incurring high toxicological risk. In this paper we investigate the use of the skin biopsies as a non-lethal tool for evaluating toxicological hazard of organochlorines in Mediterranean cetaceans, presenting new data 10 years after the paper published by Fossi and co-workers [Mar. Poll. Bull. 24 (9) (1992) 459] in which this new methodology was first presented. Some organochlorine compounds, now with worldwide distribution, are known as endocrine disrupting chemicals (EDCs). Here the unexplored hypothesis that Mediterranean cetaceans are potentially at risk due to organochlorines with endocrine disrupting capacity is investigated. High concentrations of DDT metabolites and PCB congeners (known as EDCs) were found in the different Mediterranean species (Stenella coeruleoalba, Delphinus delphis, Tursiops truncatus and Balaenoptera physalus). In this paper we also propose benzo(a)pyrene monooxygenase (BPMO) activity in marine mammal skin biopsies (non-lethal biomarker) as a potential indicator of exposure to organochlorines, with special reference to the compounds with endocrine disrupting capacity. A statistically significant correlation was found between BPMO activity and organochlorine levels (DDTs, pp(')DDT, op(')DDT, PCBs and PCB99) in skin biopsies of males of B. physalus. Moreover a statistical correlation was also found between BPMO activity and DDT levels in skin biopsies of the endangered Mediterranean population of D. delphis. These results suggest that BPMO induction may be an early sign of exposure to organochlorine EDCs and can be used for periodic monitoring of Mediterranean marine mammal toxicological status.

Uterine responsiveness to estradiol and DNA methylation are altered by fetal exposure to diethylstilbestrol and methoxychlor in CD-1 mice: effects of low versus high doses

We examined the effects on female CD-1 mice of fetal exposure to low doses of the drug diethylstilbestrol (DES) (0.1 microg/kg/day) and the insecticide methoxychlor (MXC) (10 microg/kg/day) as well as 1000-fold higher doses: 100 microg/kg/day DES and 10,000 microg/kg/day MXC. Pregnant females were administered these chemicals on gestation days 12-18. At 7-8 months of age, female offspring were ovariectomized and implanted for 7 days with a Silastic capsule containing estradiol. Relative to controls, females exposed to the 0.1 microg DES dose showed significantly heavier uteri, while females exposed to the 100 microg DES dose showed significantly lighter uteri. Females exposed prenatally to the 10 microg/kg dose of MXC had significantly heavier uteri relative to females exposed to the 10,000 microg/kg dose of MXC, but neither group differed significantly from controls. Liver weight for females exposed to both doses of DES was significantly greater than controls. Using a microarray approach to analyze DNA methylation, an increase in ribosomal DNA (rDNA) methylation was observed. Sequence data and Southern analysis indicate an increase in 18S rDNA and 45S pre-rDNA methylation in uterine samples exposed prenatally to low and high doses of DES. We thus found opposite effects of fetal exposure to a low and a high dose of DES on the uterine response to estradiol (inverted-U dose-response relationship). In contrast, there was a monotonic dose-response relationship found for prenatal DES exposure on both liver weight and ribosomal DNA hypermethylation.

Are the mediterraneantop predators exposed to toxicological risk due to endocrine disrupters?

Man-made endocrine disrupting chemicals (EDCs) range across all continents and oceans; some geographic areas are potentially more threatened than others: one of these is the Mediterranean Sea. This basin has limited exchange of water with the Atlantic Ocean and is surrounded by some of the most heavily populated and industrialized countries in the world. Accordingly, levels of some xenobiotics are much higher here than in other seas and oceans. In this research the unexplored hypothesis that Mediterranean top predator species (such as large pelagic fish and marine mammals) are potentially at risk due to EDCs is investigated. Here we illustrate the development of sensitive biomarkers (Vitellogenin, Zona Radiata proteins) for evaluation of toxicological risk in top marine predators (Xiphias gladius, Thunnus thynnus thynnus), and nonlethal techniques, such as nondestructive biomarkers (BPMO activities in skin biopsy), for the hazard assessment of threatened species exposed to EDCs, such as marine mammals (Stenella coeruleoalba, Tursiops truncatus, Delphinus delphis, and Balaenoptera physalus).

Do endocrine disrupting chemicals threaten Mediterranean swordfish? Preliminary results of vitellogenin and Zona radiata proteins in Xiphias gladius

Endocrine Disrupting Chemicals (EDCs) have the potential to alter hormone pathways that regulate reproductive processes in wildlife and fishes. In this research the hypothesis that Mediterranean top predator species (such as large pelagic fish) are potentially at risk due to EDCs is investigated. These marine organisms tend to accumulate high concentrations of EDCs such as polyhalogenated aromatic hydrocarbons (PHAHs). The potential effects of EDCs on a fish species of commercial interest, the top predator Xiphias gladius (swordfish), were investigated using vitellogenin (Vtg) and Zona radiata proteins (Zrp) as diagnostic and prognostic biomarkers. Dramatic induction of typically female proteins (Vtg and Zrp) was detected by ELISA and Western Blot in adult males of the species. These results are the first warning of the potential risk for reproductive function of Mediterranean top predators, and suggest the need for continuous monitoring of this fragile marine environment.

Non-competitive inhibition of kainate-induced currents by diethylstilbestrol in acutely isolated mouse CA1 hippocampal neurons

The effect of a synthetic estrogen, diethylstilbestrol (DES), on kainate-induced currents was investigated in the hippocampal CA1 pyramidal neurons acutely dissociated from the mice using the nystatin-perforated patch-clamp recording configuration under voltage-clamp conditions. DES inhibited the current evoked by 100 microM kainate in a concentration-dependent manner with a half-maximum inhibitory concentration of 8.8 microM. The action of DES was voltage-independent. Since DES produced a suppression of the maximum response of the kainate concentration-response curve, the inhibition by DES of the kainate-induced current appears to be non-competitive.

Women's health and the environment: innovations in science and policy

Current scientific findings indicate that environmental factors affect women's health. Specifically, evidence has accumulated on the effects of the environment on reproductive health, cancer, injury, respiratory problems, autoimmune diseases, and other health problems. To review the current state of the science and policies related to women's health and the environment, the Federal Interagency Working Group on Women's Health and the Environment of the Department of Health and Human Services and the Society for Women's Health Research jointly sponsored a conference in 1998 entitled Women's Health and the Environment: Innovations in Science and Policy. The aim of the conference was to provide a forum for scientists to share recent findings, promising avenues of research, methodological barriers, and data gaps about women's susceptibility to environmental agents. The conference generated 22 recommendations for policy, 17 recommendations for communication and training, and 48 recommendations for research to be considered by the federal government. The purpose of this review is to bring to the attention of the scientific community and policymakers the breadth of the women's health implications associated with environmental factors by highlighting key research findings presented at the conference. This review summarizes the current status of science in women's health, it describes relevant activities by the federal government, and it suggests recommendations for future research and policy initiatives in the context of women's health and the environment.

Neurotoxic effects of endocrine disruptors

Endocrine disrupting chemicals are a newly defined category of environmental contaminants that may affect animal and human populations by interfering with normal hormone action. There is substantial concern that these agents could have a range of subtle and long-lasting effects. Because of the sensitivity of the developing central nervous system to low levels of endogenous gonadal hormones during development, the central nervous system may be a target for the action of endocrine disrupting chemicals.