Lindane may modulate the female reproductive development through the interaction with ER-beta: an in vivo-in vitro approach

Tox21-Based Comparative Analyses for the Identification of Potential Toxic Effects of Environmental Pollutants

Chemical pollution has become a prominent environmental problem. In recent years, quantitative high-throughput screening (qHTS) assays have been developed for the fast assessment of chemicals' toxic effects. Toxicology in the 21st Century (Tox21) is a well-known and continuously developing qHTS project. Recent reports utilizing Tox21 data have mainly focused on setting up mathematical models for in vivo toxicity predictions, with less attention to intuitive qHTS data visualization. In this study, we attempted to reveal and summarize the toxic effects of environmental pollutants by analyzing and visualizing Tox21 qHTS data. Via PubMed text mining, toxicity/structure clustering, and manual classification, we detected a total of 158 chemicals of environmental concern (COECs) from the Tox21 library that we classified into 13 COEC groups based on structure and activity similarities. By visualizing these COEC groups' bioactivities, we demonstrated that COECs frequently displayed androgen and progesterone antagonistic effects, xenobiotic receptor agonistic roles, and mitochondrial toxicity. We also revealed many other potential targets of the 13 COEC groups, which were not well illustrated yet, and that current Tox21 assays may not correctly classify known teratogens. In conclusion, we provide a feasible method to intuitively understand qHTS data.

Intracellular distribution of vinclozolin and its metabolites differently affects 5α-dihydrotestosterone (DHT)-induced PSA secretion in LNCaP cells

Endocrine disruption mechanisms in prostate are an overlooked issue. The anti-androgenic properties of the fungicide vinclozolin (VIN) and its active metabolites - 2-[[(3,5- dichlorophenyl)-carbamoyl]oxy]-2-methyl-3-butenoic acid (M1) and 3'5'-dichloro-2-hydroxy-2- methylbut-3-enanilide (M2) - were assessed on human prostate-derived cells (LNCaP); the effects were investigated also upon co-treatment with 5α-dihydrotestosterone (DHT), the physiological androgen receptor (AR)-agonist, and compared to the anti-androgenic drugs, 2-hydroxy-flutamide (2OH-FTA) and bicalutamide (BIC). Assessed endpoints were the cellular uptake and subcellular localization of VIN, M1 and M2, DHT-induced PSA gene expression and secretion. VIN, its metabolites, and the reference drugs, significantly reduced DHT-induced PSA secretion and gene expression, M2 showing the strongest downregulation. In absence of DHT, 2OH-FTA and BIC showed a very high (>98%) LNCaP uptake with a predominant intranuclear localization (BIC=80%, 2OH-FTA=70%). VIN cellular uptake was 42%: 24.7% made up by M2, mostly localized at nuclear level, differently from VIN and M1. Upon DHT co-treatment, VIN intracellular uptake increased by 28%, especially in the microsomal fraction (MF); M2 also increased mainly in MF but also, to a lower extent, in the intranuclear fraction. Finally, in a 72-hr time-course, the LNCaP uptake of VIN and its metabolites was much faster compared to purified M1 and M2. Overall, M2 resulted the leading compound for VIN endocrine-disrupting effects in LNCaP.

Killing two birds with one stone: Pregnancy is a sensitive window for endocrine effects on both the mother and the fetus

Pregnancy is a complex process requiring tremendous physiological changes in the mother in order to fulfill the needs of the growing fetus, and to give birth, expel the placenta and nurse the newborn. These physiological modifications are accompanied with psychological changes, as well as with variations in habits and behaviors. As a result, this period of life is considered as a sensitive window as impaired functional and physiological changes in the mother can have short- and long-term impacts on her health. In addition, dysregulation of the placenta and of mechanisms governing placentation have been linked to chronic diseases later-on in life for the fetus, in a concept known as the Developmental Origin of Health and Diseases (DOHaD). This concept stipulates that any change in the environment during the pre-conception and perinatal (in utero life and neonatal) period to puberty, can be "imprinted" in the organism, thereby impacting the health and risk of chronic diseases later in life. Pregnancy is a succession of events that is regulated, in large part, by hormones and growth factors. Therefore, small changes in hormonal balance can have important effects on both the mother and the developing fetus. An increasing number of studies demonstrate that exposure to endocrine disrupting compounds (EDCs) affect both the mother and the fetus giving rise to growing concerns surrounding these exposures. This review will give an overview of changes that happen during pregnancy with respect to the mother, the placenta, and the fetus, and of the current literature regarding the effects of EDCs during this specific sensitive window of exposure.

Effects on Puberty of Nutrition-Mediated Endocrine Disruptors Employed in Agriculture

Pesticide residues are largely found in daily consumed food because of their extensive use in farming and their long half-life, which prolongs their presence in the environment. Many of these pesticides act as endocrine-disrupting chemicals after pre- or postnatal exposure, significantly affecting, among other things, the time of puberty onset, progression, and completion. In humans, precocious or delayed puberty, and early or delayed sexual maturation, may entail several negative long-term health implications. In this review, we summarize the current evidence on the impact of endocrine-disrupting pesticides upon the timing of the landmarks of female and male puberty in both animals (vaginal opening, first estrus, and balanopreputial separation) and humans (thelarche, menarche, gonadarche). Moreover, we explore the possible mechanisms of action of the reviewed endocrine-disrupting pesticides on the human reproductive system. Access to safe, healthy, and nutritious food is fundamental for the maintenance of health and wellbeing. Eliminating the presence of hazardous chemicals in largely consumed food products may increase their nutritional value and be proven beneficial for overall health. Consequently, understanding the effects of human exposure to hazardous endocrine-disrupting pesticides, and legislating against their circulation, are of major importance for the protection of health in vulnerable populations, such as children and adolescents.

Nuclear Receptors in Asthma: Empowering Classical Molecules Against a Contemporary Ailment

The escalation in living standards and adoption of 'Western lifestyle' has an allied effect on the increased allergy and asthma burden in both developed and developing countries. Current scientific reports bespeak an association between allergic diseases and metabolic dysfunction; hinting toward the critical requirement of organized lifestyle and dietary habits. The ubiquitous nuclear receptors (NRs) translate metabolic stimuli into gene regulatory signals, integrating diet inflences to overall developmental and physiological processes. As a consequence of such promising attributes, nuclear receptors have historically been at the cutting edge of pharmacy world. This review discusses the recent findings that feature the cardinal importance of nuclear receptors and how they can be instrumental in modulating current asthma pharmacology. Further, it highlights a possible future employment of therapy involving dietary supplements and synthetic ligands that would engage NRs and aid in eliminating both asthma and linked comorbidities. Therefore, uncovering new and evolving roles through analysis of genomic changes would represent a feasible approach in both prevention and alleviation of asthma.

Transcriptional response of zebrafish larvae exposed to lindane reveals two detoxification genes of ABC transporter family (abcg5 and abcg8)

Lindane is a highly toxic organochlorine pesticide and widely exist in water with harmful effects on fish. Although some genes have been found to be regulated by lindane in fish, the transcriptional response of fish exposed to lindane is still unknown. In this research, the transcriptional changes of zebrafish larvae exposed to 0.2 mg/L lindane from 96 to 120 hpf were studied by RNA sequencing. Our transcriptome identified 554 up-regulated and 118 down-regulated genes and the differentially expressed genes were closely related to the neuromast development, RNA silencing genes, ion transport, and response to estrogen. In addition, we characterized two sensitive and novel lindane-induced ABCG (ATP binding cassette G subfamily) transporter genes- abcg5 and abcg8. Abcg5 and abcg8 genes are located on chromosome 13 of zebrafish and contain 1956/2024 bp open reading frame. The polypeptide deduced by CDS amplification contains 652/676 amino acids and has most of the functional domains and key residues defined in human and mouse ABCG5/Abcg5 or ABCG8/Abcg8. Only when the co-expression of Abcg5 and Abcg8 enable them to transport to the cell membrane surface in 293T cells. In addition, lindane can induce the transcriptional expression of abcg5 and abcg8 genes, and overexpression of Abcg5 and Abcg8 significantly reduced the toxicity of lindane to zebrafish larvae, which means that zebrafish Abcg5 and Abcg8 are potential efflux transporters of lindane. Therefore, these findings provide useful insights for further understanding the zebrafish larvae's transcriptional response and detoxification ability after acute exposure to lindane.

Endocrine Disrupters and the Safety of Food Chains

Endocrine disrupters (ED) are a heterogeneous group of chemicals including persistent contaminants, pesticides, as well as compounds present in consumer products and natural substances. For most ED, the food chain is a current major exposure route for the general population. ED can enter the food chain through the living environment (e.g., feeds, fertilizers) of food-producing organisms, be directly employed in food production (e.g., pesticides) or be released from food contact materials (such as bisphenol A or phthalates); in addition, the endocrine disruption potential of some natural compounds in edible plants, including the so-called phytoestrogens, should not be overlooked. An exposure assessment has to consider the specific liability of food commodities to contamination with specific ED (e.g., polychlorinated and polybrominated chemicals in lipid-rich foods). The paper discusses the main toxicological research issues in order to support the risk assessment of ED in food chains, including: the potential for additive, 'cocktail' effects (as from multiple pesticide residues); the long-term effects on target body systems (e.g., reproductive, nervous) elicited by exposure during prenatal as well as postnatal life stage windows, and toxicant/nutrient interactions (e.g., thyroid-targeting ED and iodine status). Food safety systems should exploit the available knowledge to improve prevention of long-term risks along the whole food chain.

Ecotoxicological assessment of soils polluted with chemical waste from lindane production: Use of bacterial communities and earthworms as bioremediation tools

An ecotoxicological survey of soils that were polluted with wastes from lindane (γ-HCH) production assessed the effects of organochlorine compounds on the metabolism of microbial communities and the toxicity of these compounds to a native earthworm (Allolobophora chlorotica). Furthermore, the bioremediation role of earthworms as facilitators of soil washing and the microbial degradation of these organic pollutants were also studied. Soil samples that presented the highest concentrations of ε-HCH, 2,4,6-trichlorophenol, pentachlorobenzene and γ-HCH were extremely toxic to earthworms in the short term, causing the death of almost half of the population. In addition, these soils inhibited the heterotrophic metabolic activity of the microbial community. These highly polluted samples also presented substances that were able to activate cellular detoxification mechanisms (measured as EROD and BFCOD activities), as well as compounds that were able to cause endocrine disruption. A few days of earthworm activity increased the extractability of HCH isomers (e.g., γ-HCH), facilitating the biodegradation of organochlorine compounds and reducing the intensity of endocrine disruption in soils that had low or medium contamination levels.

Endocrine Disruptors Leading to Obesity and Related Diseases

The review aims to comprehensively present the impact of exposure to endocrine disruptors (EDs) in relation to the clinical manifestation of obesity and related diseases, including diabetes mellitus, metabolic syndrome, cardiovascular diseases, carcinogenesis and infertility. EDs are strong participants in the obesity epidemic scenery by interfering with cellular morphological and biochemical processes; by inducing inflammatory responses; and by presenting transcriptional and oncogenic activity. Obesity and lipotoxicity enhancement occur through reprogramming and/or remodeling of germline epigenome by exposure to EDs. Specific population groups are vulnerable to ED exposure due to current dietary and environmental conditions. Obesity, morbidity and carcinogenicity induced by ED exposure are an evolving reality. Therefore, a new collective strategic approach is deemed essential, for the reappraisal of current global conditions pertaining to energy management.

Metabolism disrupting chemicals and metabolic disorders

The recent epidemics of metabolic diseases, obesity, type 2 diabetes(T2D), liver lipid disorders and metabolic syndrome have largely been attributed to genetic background and changes in diet, exercise and aging. However, there is now considerable evidence that other environmental factors may contribute to the rapid increase in the incidence of these metabolic diseases. This review will examine changes to the incidence of obesity, T2D and non-alcoholic fatty liver disease (NAFLD), the contribution of genetics to these disorders and describe the role of the endocrine system in these metabolic disorders. It will then specifically focus on the role of endocrine disrupting chemicals (EDCs) in the etiology of obesity, T2D and NAFLD while finally integrating the information on EDCs on multiple metabolic disorders that could lead to metabolic syndrome. We will specifically examine evidence linking EDC exposures during critical periods of development with metabolic diseases that manifest later in life and across generations.

Bisphenol A affects placental layers morphology and angiogenesis during early pregnancy phase in mice

Bisphenol A (BPA) is a widespread endocrine disrupter mainly used in food contact plastics. Much evidence supports the adverse effects of BPA, particularly on susceptible groups such as pregnant women. The present study considered placental development - relevant for pregnancy outcomes and fetal nutrition/programming - as a potential target of BPA. Pregnant CD-1 mice were administered per os with vehicle, 0.5 (BPA05) or 50 mg kg(-1) (BPA50) body weight day(-1) of BPA, from gestational day (GD) 1 to GD11. At GD12, BPA50 induced significant degeneration and necrosis of giant cells, increased vacuolization in the junctional zone in the absence of glycogen accumulation and reduction of the spongiotrophoblast layer. In addition, BPA05 induced glycogen depletion as well as significant nuclear accumulation of β-catenin in trophoblasts of labyrinthine and spongiotrophoblast layers, supporting the activation of the Wnt/β-catenin pathway. Transcriptomic analysis indicated that BPA05 promoted and BPA50 inhibited blood vessel development and branching; morphologically, maternal vessels were narrower in BPA05 placentas, whereas embryonic and maternal vessels were irregularly dilated in the labyrinth of BPA50 placentas. Quantitative polymerase chain reaction evidenced an estrogen receptor β induction by BPA50, which did not correspond to downstream genes activation; indeed, the transcription factor binding sites analysis supported the AhR/Arnt complex as regulator of BPA50-modulated genes. Conversely, Creb appeared as the main transcription factor regulating BPA05-modulated genes. Embryonic structures (head, forelimb) showed divergent perturbations upon BPA05 or BPA50 exposure, potentially related to unbalanced embryonic nutrition and/or to modulation of genes involved in embryo development. Our findings support placenta as an important target of BPA, even at environmentally relevant dose levels.

Endocrine disruptors and female cancer: Informing the patients (Review)

Pollutants altering the endocrine system, known as endocrine disruptors (ED), may modify the risk of female cancers. The carcinogenic effect of ED on humans has been confirmed by experimental studies for various substances including pesticides, DDT, dioxins, phthalates, bisphenol A, diethylstilbestrol, as well as heavy metals, but it is difficult to quantify precisely for several reasons hereby reviewed. Carcinogenesis is a complex and multifactorial mechanism that manifests itself over a long period of time, making difficult the detection of the specific contribution of the pollutants, whose absorbed dose is often unknown. The combined effect of various substances leads to complex interactions whose outcome is difficult to predict. These substances may accumulate and carry out their harmful effect on critical periods of life, probably also at doses considered harmless to an adult. ED can also have epigenetic adverse effects on the health of future generations. In conclusion, the carcinogenic effects of endocrine disruptors on female cancer types is plausible although additional studies are needed to clarify their mechanisms and entities. In the last part of the review we suggest ways to reduce ED exposure as it is mandatory to implement necessary measures to limit exposure, particularly during those periods of life most vulnerable to the impact of oncogenic environmental causes, such as the embryonic period and puberty.

Estrogenic evaluation and organochlorine identification in blubber of North Sea harbour porpoise (Phocoena phocoena) stranded on the North Sea coast

Thirteen individual organochlorine compounds at 3 concentrations (80, 400, and 2000 ng/mL culture medium), as well as mixtures, were assayed for the estrogen receptor (ER) activation or inhibition, using a luciferase reporter gene assay (RGA). None of the PCB 138, 153, or 180 or their mixture induced a response in the RGA. o,p′-DDT was the most potent xenoestrogen from the DDT group, inducing a response already at 80 ng/mL. From the HCH and HCB group, only β-HCH (at 400 and 2000 ng/mL) and δ-HCH (at 2000 ng/mL) displayed estrogenic activities. These 13 organochlorines were determined by GC-MS in 12 samples of North Sea harbor porpoise blubber. The PCBs were the main contaminants. Within each group, PCB 153 (6.0 × 10²~4.2 × 10⁴  μg/kg), p,p′-DDE (5.1 × 10²~8.6 × 10³  μg/kg), and HCB (7.6 × 10¹~1.5 × 10³  μg/kg) were the compounds found in highest concentrations. The hormonal activity of the porpoise blubber samples was also assayed in RGA, where two samples showed estrogenic activity, seven samples showed antiestrogenic activity, and one sample showed both estrogenic and antiestrogenic activity. Our results suggest that the 13 POPs measured by GC-MS in the samples cannot explain alone the estrogenicity of the extracts.

Effect of quercetin against lindane induced alterations in the serum and hepatic tissue lipids in wistar rats

OBJECTIVE

To assess the effect of quercetin (flavonoid) against lindane induced alterations in lipid profile of wistar rats.

METHODS

Rats were administered orally with lindane (100 mg/kg body weight) and quercetin (10 mg/kg body weight) for 30 days. After the end of treatment period lipid profile was estimated in serum and tissue.

RESULTS

Elevated levels of serum cholesterol, triglycerides, low density lipoprotein (LDL), very Low Density Lipoprotein (VLDL) and tissue triglycerides, cholesterol with concomitant decrease in serum HDL and tissue phospholipids were decreased in lindane treated rats were found to be significantly decreased in the quercetin and lindane co-treated rats.

CONCLUSIONS

Our study suggests that quercetin has hypolipidemic effect and offers protection against lindane induced toxicity in liver by restoring the altered levels of lipids. The quercetin cotreatment along with lindane for 30 days reversed these biochemical alterations in lipids induced by lindane.

Serum organochlorine pesticide residues and risk of gallstone disease: a case-control study in Xiamen

PURPOSE

To investigate the association between serum organochlorine pesticide residues and risk of gallstone disease.

METHODS

A 1:1, pair-matched, case-control study was designed. Data from 150 patients with gallstones diagnosed by abdominal ultrasonography at a single hospital from June 2009 to June 2010 were collected. A total of 150 patients without gallstones during the same period at the same hospital were recruited as the control group. Capillary gas chromatography was employed to measure the serum concentrations of dichlorodiphenyltrichloroethane (DDT) and hexachlorocyclohexane (HCH) residues. Multiple-factor conditional logistic regression analysis was conducted to estimate the relative risk of gallstones in relation to organochlorine pesticide residues in serum.

RESULTS

The percentages of p,p'-DDD and o,p'-DDT in serum of patients were significantly higher than those in serum of controls. The p,p'-DDE, α-HCH, and δ-HCH residues in serum of patients were also significantly increased compared with those in serum of controls. Multiple-factor conditional logistic regression analysis showed that high levels of p,p'-DDE and p,p'-DDT residues were risk factors for gallstone disease.

CONCLUSIONS

A high level of organochlorine pesticide residues in serum is a potential risk factor for gallstone disease, which suggests that environmental exposure to organochlorine pesticides should be evaluated with respect to gallstone formation.

Using Representational Difference Analysis to detect changes in transcript expression of Aiptasia genes after laboratory exposure to lindane

Molecular stress responses to pesticide exposures represent an understudied area of cnidarian transcriptome investigations. The organochlorine pesticide lindane is known to disrupt normal neuron function. Cnidarians with simple nervous systems are recognized as sensitive indicators of water quality, yet nothing is known about cnidarian responses to lindane. Sea anemones (Aiptasia pallida) were exposed for 4h to lindane (20 μg/l). Because anemones have neurons and lindane is known to target neurons, it is anticipated that cnidarian stress responses will include changes in transcription of genes associated with neurons. Representational Difference Analysis (RDA) was utilized to isolate differentially transcribed genes in the anemones exposed to the pesticide. After two rounds of RDA hybridizations, 148 amplified fragments ranging in size from 150 to 800 bp were cloned. Sequencing and bioinformatic analyses of 106 clones revealed 56 different gene fragments. Virtual Northern dot blots were used as a preliminary screening tool to identify the most responsive RDA products. To further characterize the specificity of response, additional anemones were exposed to a series of lindane concentrations (0, 0.2, 2.0, 10, and 20 μg/l). Northern dot blots were subsequently used to develop expression profiles for selected RDA products over the range of pesticide concentrations. The seven most responsive RDA products represent genes with products associated with neuron development, immune responses, and Ca(2+) binding/transport. The resulting expression profiles illustrate that these RDA products exhibit various degrees of concentration specificity with some RDA products being significantly up-regulated at 20 μg/l while other RDA products are most responsive at concentrations <20 μg/l. Results also demonstrate how RDA can be used to identify potentially important biomarkers of organochlorine exposure while generating new hypotheses about important phenomena such as endocrine disruption in cnidarians.

Hormonal link to autoimmune allergies

IgE recognition of autoantigens might augment allergic inflammation in the absence of exogenous allergen exposure. Among allergy and autoimmunity, there is disproportionate representation of males before puberty and females after puberty, suggesting a role for sex hormones. Hormone allergy is an allergic reaction where the offending allergens are one's own hormones. It is an immune reaction to the hormones, which can interfere with the normal function of the hormones. It can occur perimenstrually in women along with the variation in menstrual cycle. The perimenstrual allergies are about the cyclic abundance of the hormone causing a cyclic expression of allergic symptoms. The inflammatory mechanisms of allergic reactions to hormone allergens, which are intrinsic to the body, are the same as the mechanisms of allergic reactions to external allergens.

Biochemical effects induced by the hexachlorocyclohexanes

The hexachlorocyclohexanes (HCHs) are synthetic compounds that have been widely used for the control of pests. The most common HCH isomers are the α-, β-, δ-, and γ-HCH. Although the have the same chlorine substitution pattern, the spatial orientation of chlorine atoms is different on each one of them, resulting in unique structures that have distinct molecular properties. Humans are exposed to individual HCH isomers through various routes, including ingestion of contaminated water or food, absorbed through the skin or by inhalation, and because of their liposolubility, these chemicals are mostly stored in fat-containing tissues. The isomer-specific spectrum of biochemical actions for these compounds has been wee characterized for different endpoints such as enzyme activation, calcium homeostasis, gap junctional intercellular communication, endocrine disruption, and cancer, among others. The interaction with the GABA reception has been one of the most extensively studied properties of the HCHs. For instance, γ-HCH acts as a GABAA channel blocker, whereas α- and δ-HCH potentiate currents , all working as allosteric modulators of the receptor. The changes in calcium homeostasis elicited by HCHs are both isomer and cell type specific. For example, in neurons, both the δ- and γ-isomers of HCH stimulate Ca²+ influx through different voltage-gated Ca²+ channels. In human neutrophils, α-,δ-, and γ-HCH, but not β-HCH, increase intracellular Ca²+ concentrations. This isomer-dependent behavior is also similar to that observed for phospholipase A2 activation and also correlates with oxidative stress generation. On the other hand, there are several lines of evidence suggesting that HCHs alter genomic integrity, and, therefore, these compounds have been classified as possibly carcinogenic to humans . Finally, HCHs have been reported to be endocrine disrupters. In fact, γ- and β-HCH have been shown to have weak estrogenic activity, and together with the α- and the δ-isomer, also interfere with steroidogenesis. In short, the HCH isomers are good examples of structurally related chemicals, for which the geometrical patterns present in each one of the different conformers create structures that possess specific mechanisms of action and toxicological properties.

Self-reported chemicals exposure, beliefs about disease causation, and risk of breast cancer in the Cape Cod Breast Cancer and Environment Study: a case-control study

BACKGROUND

Household cleaning and pesticide products may contribute to breast cancer because many contain endocrine disrupting chemicals or mammary gland carcinogens. This population-based case-control study investigated whether use of household cleaners and pesticides increases breast cancer risk.

METHODS

Participants were 787 Cape Cod, Massachusetts, women diagnosed with breast cancer between 1988 and 1995 and 721 controls. Telephone interviews asked about product use, beliefs about breast cancer etiology, and established and suspected breast cancer risk factors. To evaluate potential recall bias, we stratified product-use odds ratios by beliefs about whether chemicals and pollutants contribute to breast cancer; we compared these results with odds ratios for family history (which are less subject to recall bias) stratified by beliefs about heredity.

RESULTS

Breast cancer risk increased two-fold in the highest compared with lowest quartile of self-reported combined cleaning product use (Adjusted OR = 2.1, 95% CI: 1.4, 3.3) and combined air freshener use (Adjusted OR = 1.9, 95% CI: 1.2, 3.0). Little association was observed with pesticide use. In stratified analyses, cleaning products odds ratios were more elevated among participants who believed pollutants contribute "a lot" to breast cancer and moved towards the null among the other participants. In comparison, the odds ratio for breast cancer and family history was markedly higher among women who believed that heredity contributes "a lot" (OR = 2.6, 95% CI: 1.9, 3.6) and not elevated among others (OR = 0.7, 95% CI: 0.5, 1.1).

CONCLUSIONS

Results of this study suggest that cleaning product use contributes to increased breast cancer risk. However, results also highlight the difficulty of distinguishing in retrospective self-report studies between valid associations and the influence of recall bias. Recall bias may influence higher odds ratios for product use among participants who believed that chemicals and pollutants contribute to breast cancer. Alternatively, the influence of experience on beliefs is another explanation, illustrated by the protective odds ratio for family history among women who do not believe heredity contributes "a lot." Because exposure to chemicals from household cleaning products is a biologically plausible cause of breast cancer and avoidable, associations reported here should be further examined prospectively.

In utero exposure to di-(2-ethylhexyl) phthalate affects liver morphology and metabolism in post-natal CD-1 mice

The plasticizer di-(2-ethylhexyl)phthalate (DEHP) affects reproductive development, glycogen and lipid metabolism. Whereas liver is a main DEHP target in adult rodents, the potential impact on metabolic programming is unknown. Effects of in utero DEHP exposure on liver development were investigated upon treatment of pregnant CD-1 mice on gestational days (GD)11-19. F1 mice were examined at post-natal days 21 (weaning) and 35 (start of puberty): parameters included liver histopathological, immunocytochemical and alpha-fetoprotein (AFP) gene expression analyses. In utero DEHP exposure altered post-natal liver development in weanling mice causing significant, dose-related (i) increased hepatosteatosis, (ii) decreased glycogen storage, (iii) increased beta-catenin intracytoplasmic localization (females only). At puberty, significantly decreased glycogen storage was still present in males. A treatment-induced phenotype was identified with lack of glycogen accumulation and intracytoplasmic localization of beta-catenin which was associated with increased AFP gene expression. Our findings suggested that DEHP alters post-natal liver development delaying the programming of glycogen metabolism.

Toxicology in the fast lane: application of high-throughput bioassays to detect modulation of key enzymes and receptors

BACKGROUND

Legislation at state, federal, and international levels is requiring rapid evaluation of the toxicity of numerous chemicals. Whole-animal toxicologic studies cannot yield the necessary throughput in a cost-effective fashion, leading to a critical need for a faster and more cost-effective toxicologic evaluation of xenobiotics.

OBJECTIVES

We tested whether mechanistically based screening assays can rapidly provide information on the potential for compounds to affect key enzymes and receptor targets, thus identifying those compounds requiring further in-depth analysis.

METHODS

A library of 176 synthetic chemicals was prepared and examined in a high-throughput screening (HTS) manner using nine enzyme-based and five receptor-based bioassays.

RESULTS

All the assays have high Z' values, indicating good discrimination among compounds in a reliable fashion, and thus are suitable for HTS assays. On average, three positive hits were obtained per assay. Although we identified compounds that were previously shown to inhibit a particular enzyme class or receptor, we surprisingly discovered that triclosan, a microbiocide present in personal care products, inhibits carboxylesterases and that dichlone, a fungicide, strongly inhibits the ryanodine receptors.

CONCLUSIONS

Considering the need to rapidly screen tens of thousands of anthropogenic compounds, our study shows the feasibility of using combined HTS assays as a novel approach toward obtaining toxicologic data on numerous biological end points. The HTS assay approach is very useful to quickly identify potentially hazardous compounds and to prioritize them for further in-depth studies.

Effects of the food contaminant semicarbazide following oral administration in juvenile Sprague-Dawley rats

Semicarbazide (SEM) is an azodicarbonamide by-product present in glass jar packaged foods including babyfoods, in bleaching steps and flour treatment. Experimental data showed SEM acting as osteolathyrogen agent, but few toxicological data are available in susceptible life-stages. This study aimed to evaluate effects of SEM oral administration for 28 days at 0, 40, 75, 140 mg/kg bw day during the juvenile period in Sprague-Dawley rats. Histopatological examinations of: epiphyseal cartilage - potential target of SEM lathyrogen action - testes, ovary, uterus, thyroid, thymus, spleen, adrenals, representative of the main developing organs relevant to juvenile toxicity, and neurobehavioural tests in males, were performed. Mortality at high and mid dose levels and significantly decreased body weight gain were observed in males even at the lowest dose. Lack of mineralization in cartilage at all dose levels was present. Marked alterations of spontaneous motor and exploratory behaviours were evident even at 40 mg/kg. Histological alterations were observed in all tissues; thyroid and ovary effects were present also at 40 mg/kg. The present study indicate that the NOAEL in juvenile rats is lower than 40 mg/kg for SEM oral administration. SEM administration during juvenile period exerted pleiotropic effects and further studies are suggested to elucidate mechanisms.

Effects of a low oral dose of diethylstilbestrol (DES) on reproductive tract development in F1 female CD-1 mice

The synthetic estrogen diethylstilbestrol (DES) is a model to study the effects on female reproductive tract of endocrine disrupting chemicals interacting with estrogen receptors. Pregnant CD-1 mice were given daily by gavage 10microg/kg bw of DES (the lower range of therapeutic exposure) during gestational days 9-16, critical period for reproductive tract development. Parameters of sexual development were recorded after weaning and at sexual maturation. No signs of general toxicity were observed in dams. In DES-treated group, reduced litter weight during lactation and earlier vaginal patency was observed. Uterus weight was increased in F1 treated females at weaning. Histological analysis showed reduced endometrium thickness and increased polyovular follicles, irregular and oocytes with condensed chromatin in the ovary at sexual maturity. Prenatal DES oral administration induces subtle but significant effects on puberty onset, uterine and ovary morphology.

Gender-medicine aspects in allergology

Despite the identical immunological mechanisms activating the release of mediators and consecutive symptoms in immediate-type allergy, there is still a clear clinical difference between female and male allergic patients. Even though the risk of being allergic is greater for boys in childhood, almost from adolescence onwards it seems to be a clear disadvantage to be a woman as far as atopic disorders are concerned. Asthma, food allergies and anaphylaxis are more frequently diagnosed in females. In turn, asthma and hay fever are associated with irregular menstruation. Pointing towards a role of sex hormones, an association of asthma and intake of contraceptives, and a risk for asthma exacerbations during pregnancy have been observed. Moreover, peri- and postmenopausal women were reported to increasingly suffer from asthma, wheeze and hay fever, being even enhanced by hormone replacement therapy. This may be on account of the recently identified oestradiol-receptor-dependent mast-cell activation. As a paradox of nature, women may even become hypersensitive against their own sex hormones, resulting in positive reactivity upon intradermal injection of oestrogen or progesterone. More importantly, this specific hypersensitivity is associated with recurrent miscarriages. Even though there is a striking gender-specific bias in IgE-mediated allergic diseases, public awareness of this fact still remains minimal today.

Responsiveness of cerebral and hepatic cytochrome P450s in rat offspring prenatally exposed to lindane

Prenatal exposure to low doses of lindane has been shown to affect the ontogeny of xenobiotic metabolizing cytochrome P450s (CYPs), involved in the metabolism and neurobehavioral toxicity of lindane. Attempts were made in the present study to investigate the responsiveness of CYPs in offspring prenatally exposed to lindane (0.25 mg/kg b. wt.; 1/350th of LD(50); p. o. to mother) when challenged with 3-methylcholanthrene (MC) or phenobarbital (PB), inducers of CYP1A and 2B families or a sub-convulsant dose of lindane (30 mg/kg b. wt., p. o.) later in life. Prenatal exposure to lindane was found to produce an increase in the mRNA and protein expression of CYP1A1, 1A2, 2B1, 2B2 isoforms in brain and liver of the offspring at postnatal day 50. The increased expression of the CYPs in the offspring suggests the sensitivity of the CYPs during postnatal development, possibly, to low levels of lindane, which may partition into mother's milk. A higher increase in expression of CYP1A and 2B isoenzymes and their catalytic activity was observed in animals pretreated prenatally with lindane and challenged with MC (30 mg/kg, i. p. x 5 days) or PB (80 mg/kg, i. p. x 5 days) when young at age (approx. 7 weeks) compared to animals exposed to MC or PB alone. Further, challenge of the control and prenatally exposed offspring with a single sub-convulsant dose of lindane resulted in an earlier onset and increased incidence of convulsions in the offspring prenatally exposed to lindane have demonstrated sensitivity of the CYPs in the prenatally exposed offspring. Our data assume significance as the subtle changes in the expression profiles of hepatic and cerebral CYPs in rat offspring during postnatal development could modify the adult response to a later exposure to xenobiotics.