Developmental neurotoxicity study of dietary bisphenol A in Sprague-Dawley rats

Sex Differences in Withdrawal-Induced Anxiety in Rats After Exposure to Tobacco Smoke

Nicotine, a component of cigarettes, possesses strong reinforcing properties and improves cognitive function, which can lead to dependence. Upon cigarette smoking cessation, withdrawal symptoms occur and may cause an individual to relapse. Affective withdrawal symptoms, such as anxiety, is of great concern as studies have shown its ability to cause relapse in men and women. In this in vivo study, anxiety resulting from smoking cessation after 2-day smoke-free intervals per week for the duration of 4 weeks was investigated in 8 male and 8 female rats after their exposure to cigarette smoke compared to unexposed control rats (8 males and 8 female rats). The anxiety in rats during smoke-free intervals was investigated using an elevated plus-maze (EPM), open-field (OF), and light/dark test (LD). In all tests male rats exhibited significantly higher anxiety symptoms compared to female rats during nicotine withdrawal, despite control rats showing no differences. In the EPM, male rats spent less time in open arm as well having as lower number of crossings than female rats. As for the OFT, the amount of time spent in the center of the open field was also lower in male rats than female rats. In the LD test, the time spent in the light chamber and the latency (delay) to enter the dark chamber was lower in male rats compared to female rats. Our study showed that male rats show greater nicotine withdrawal effects, in terms of anxiety-like behavior than female rats.

Phenols and GABAA receptors: from structure and molecular mechanisms action to neuropsychiatric sequelae

γ-Aminobutyric acid type A receptors (GABAARs) are members of the pentameric ligand-gated ion channel (pLGIC) family, which are widespread throughout the invertebrate and vertebrate central nervous system. GABAARs are engaged in short-term changes of the neuronal concentrations of chloride (Cl-) and bicarbonate (HCO3 -) ions by their passive permeability through the ion channel pore. GABAARs are regulated by various structurally diverse phenolic substances ranging from simple phenols to complex polyphenols. The wide chemical and structural variability of phenols suggest similar and different binding sites on GABAARs, allowing them to manifest themselves as activators, inhibitors, or allosteric ligands of GABAAR function. Interest in phenols is associated with their great potential for GABAAR modulation, but also with their subsequent negative or positive role in neurological and psychiatric disorders. This review focuses on the GABAergic deficit hypotheses during neurological and psychiatric disorders induced by various phenols. We summarize the structure-activity relationship of general phenol groups concerning their differential roles in the manifestation of neuropsychiatric symptoms. We describe and analyze the role of GABAAR subunits in manifesting various neuropathologies and the molecular mechanisms underlying their modulation by phenols. Finally, we discuss how phenol drugs can modulate GABAAR activity via desensitization and resensitization. We also demonstrate a novel pharmacological approach to treat neuropsychiatric disorders via regulation of receptor phosphorylation/dephosphorylation.

Strategic science translation in emerging science: genetically modified crops and Bisphenol A in two cases of contested animal toxicity studies

When controversies develop around scientific facts or technologies, the potential of science to become a tool in plays of interests and power between different actors is not well recognized. Cordner’s concept of Strategic Science Translation (SST) shows that such actions are enabled by the uncertainty and the complexity of the scientific processes that allow the use of science in support of various, often contradictory interests and goals. Two high-profile controversies around animal toxicity studies in two different fields of European regulatory science (genetically modified food and food contact materials) were chosen as case studies to explore and expand the SST concept. Both studies involve emerging science issues, emphasizing tensions between regulatory and academic science. Communications from key Civil Society Organizations (CSOs) and industry groups were used for analysis of each controversy. We found that both groups of actors try to present their own interpretation of scientific results, taking advantage of the lack of scientific consensus, of the uncertainties associated with the negotiation in the interpretation of results, and of the wider scientific and political context. In the same time, each actor attempts to challenge the credibility of the other. The lack of formal acknowledgment of the limitations of the emerging scientific fields, as well as of different research approaches between regulatory and academic research contribute to the continuation of controversies in the public domain, as the public cannot easily assess the information presented.

Histone deacetylase 2 inhibitor valproic acid attenuates bisphenol A-induced liver pathology in male mice

Accumulating evidence indicates the role of endocrine disruptor bisphenol A (BPA) in many pathological conditions. Histone deacetylase (HDAC) inhibition has potential for the treatment of many diseases/abnormalities. Using a mouse BPA exposure model, this study investigated the hepatoprotective effects of the Food and Drug Administration–approved HDAC2 inhibitor valproic acid (VPA) against BPA-induced liver pathology. We randomly divided 30 adult male Swiss albino mice (8 weeks old; N = 6) into five groups: group 1, no treatment (sham control (SC)); group 2, only oral sterile corn oil (vehicle control (VC)); group 3, 4 mg/kg/day of oral BPA (single dose (BPA group)); group 4, 0.4% oral VPA (VPA group); and group 5, oral BPA + VPA (BPA + VPA group). At the age of 10 weeks, the mice were euthanized for biochemical and histological examinations. BPA promoted a significant decrease in the body weight (BW), an increase in the liver weight, and a significant increase in the levels of liver damage markers aspartate aminotransferase and alanine aminotransferase in the BPA group compared to SC, as well as pathological changes in liver tissue. We also found an increase in the rate of apoptosis among hepatocytes. In addition, BPA significantly increased the levels of oxidative stress indices, malondialdehyde, and protein carbonylation but decreased the levels of reduced glutathione (GSH) in the BPA group compared to SC. In contrast, treatment with the HDAC2 inhibitor VPA significantly attenuated liver pathology, oxidative stress, and apoptosis and also enhanced GSH levels in VPA group and BPA + VPA group. The HDAC2 inhibitor VPA protects mice against BPA-induced liver pathology, likely by inhibiting oxidative stress and enhancing the levels of antioxidant-reduced GSH.

Does Bisphenol A Confer Risk of Neurodevelopmental Disorders? What We Have Learned from Developmental Neurotoxicity Studies in Animal Models

Substantial evidence indicates that bisphenol A (BPA), a ubiquitous environmental chemical used in the synthesis of polycarbonate plastics and epoxy resins, can impair brain development. Clinical and epidemiological studies exploring potential connections between BPA and neurodevelopmental disorders in humans have repeatedly identified correlations between early BPA exposure and developmental disorders, such as attention deficit/hyperactivity disorder and autism spectrum disorder. Investigations using invertebrate and vertebrate animal models have revealed that developmental exposure to BPA can impair multiple aspects of neuronal development, including neural stem cell proliferation and differentiation, synapse formation, and synaptic plasticity-neuronal phenotypes that are thought to underpin the fundamental changes in behavior-associated neurodevelopmental disorders. Consistent with neuronal phenotypes caused by BPA, behavioral analyses of BPA-treated animals have shown significant impacts on behavioral endophenotypes related to neurodevelopmental disorders, including altered locomotor activity, learning and memory deficits, and anxiety-like behavior. To contextualize the correlations between BPA and neurodevelopmental disorders in humans, this review summarizes the current literature on the developmental neurotoxicity of BPA in laboratory animals with an emphasis on neuronal phenotypes, molecular mechanisms, and behavioral outcomes. The collective works described here predominantly support the notion that gestational exposure to BPA should be regarded as a risk factor for neurodevelopmental disorders.

Precise Yet Uncertain: Broadening Understandings of Uncertainty and Policy in the BPA Controversy

Bisphenol A (BPA) is one of the most studied and most controversial chemicals used by the food packaging industry, because of its endocrine disruptive properties. Part of the controversy is due to the uncertainty that surrounds the effects of BPA on the endocrine system. Uncertainty includes data gaps, methodological hurdles, incompatibilities between toxicology and endocrinology-based approaches, and so on. In this article, we analyze how uncertainty has been conceptualized and treated. We focus on the European Food Safety Authority assessments of BPA, and study how exposure and hazard assessments have evolved over time, how uncertainty has been analyzed, and how the agency responded to controversies. Results show that in the attempt to reduce knowledge gaps, assessments have become progressively larger, including more references, evidence, and effects. There is a tendency toward greater precisions and specification of results, and toward protocolization of all processes included in the assessment (from literature review, to uncertainty assessments, and public consultation). Yet, the uncertainty has not diminished following the increase in evidence. We argue that the strategy used to reduce uncertainty within risk assessment, namely including more variables, studies, data, and methods, amplifies the uncertainty linked to indeterminacy (as more results increase the fragmentation of the knowledge base due to the open-ended nature of complex issues) and ambiguity (as complexity gives way to multiple nonequivalent interpretations of results). For this reason, it is important to consider different types of uncertainty and how these uncertainties interact with each other.

Drivers of owning more BPA

Bisphenol A (BPA) is a ubiquitous environmental toxin worldwide. Despite the many studies documenting the toxicity of this substance, it remains a popular choice for consumer products. The internet, magazine articles, and newspaper reports are replete with tips on how to avoid BPA exposure, which mostly spread contradictory and often unscientific information. Therefore, based on a comprehensive search of the available biomedical literature, we summarized several confounding factors that may be directly or indirectly related to human BPA exposure. We found that the unique properties of BPA materials (i.e. low cost, light-weight, resistance to corrosion, and water/air-tightness), lack of personal health and hygiene education, fear of BPA-substitutes (with yet unknown risks), inappropriate production, processing, and marketing of materials containing BPA, as well as the state of regulatory guidance are influencing the increased exposure to BPA. Besides, we detailed the disparities between scientifically derived safe dosages of BPA and those designated as "safe" by government regulatory agencies. Therefore, in addition to providing a current assessment of the states of academic research, government policies, and consumer behaviors, we make several reasonable and actionable recommendations for limiting human exposure to BPA through improved labeling, science-based dosage limits, and public awareness campaigns.

Protective effects of curcumin on chemical and drug-induced cardiotoxicity: a review

Cardiotoxicity is a major adverse effect that can be induced by both therapeutic agents and industrial chemicals. The pathogenesis of such cardiac damage is multifactorial, often injuring the cardiac tissue by generating free radicals, oxidative stress, and/or inflammation. Curcumin (CUR) is a bright yellow chemical produced by Curcuma longa plants. It is the principal curcuminoid of turmeric (Curcuma longa), a member of the ginger family, Zingiberaceae. Administration of CUR has been reported to ameliorate the chemical and drug-induced cardiac injury in several studies. CUR has been suggested to act as an effective candidate against oxidative stress and inflammation in heart tissue via regulation of Nrf2 and suppression of p38 MAPK/NF-κB and NLRP3 inflammasomes. The anti-apoptotic properties of CUR have also been reported to modulate the AMPK, Akt, JNK, and ERK signaling pathways. This review explores the potential protective effects of CUR regarding the detrimental effects often observed in cardiac tissue following exposure to several chemicals including drugs.

Vitamin D mitigates adult onset diseases in male and female mice induced by early-life exposure to endocrine disruptor BPA

Background

During early development, environmental compounds can induce adult onset diseases and disrupt the circulating vitamin D (VitD) levels.

Aim

This study aimed to examine the protective role of VitD against the adverse effects of BPA on male and female mice.

Methods

A total of 60 male and female Swiss Albino mice (3 weeks old) were randomly divided into 5 groups; each consisted of 12 mice (6 males and 6 females) and was treated as follows: Group I received no treatment (sham control); Group II, sterile corn oil only (vehicle control); Group III, BPA (400 μg/kg); Group IV, VitD (2,195 IU/kg); and Group V, BPA + VitD. At 10.5 weeks, the animals were sacrificed to conduct histological examinations.

Results

BPA-exposed mice were found to have neurobehavioral abnormalities, heart, kidney, and lung diseases with increased apoptotic indices in both sexes. On the other hand, the treatment of BPA mice with VitD altered this scenario with modulated motor activity, enhanced body and organ weights, and preserved the heart, kidney, and lung architecture, alongside a decreased percent apoptotic index.

Conclusion

Our findings illustrate that VitD protects mice against BPA-induced heart, kidney, and lung abnormalities.

Maternal exposure to low doses of bisphenol A affects learning and memory in male rat offspring with abnormal N-methyl-d-aspartate receptors in the hippocampus

Bisphenol A (BPA), a component of polycarbonate and epoxy resins, has been reported to induce learning and memory deficits. However, the mechanisms have not been fully elucidated. Growing evidence has suggested that N-methyl-d-aspartate receptors (NMDARs) are involved in cognitive impairments. In this study, BPA was administered to female Sprague-Dawley rats (six per dose group) at concentrations of 0 (control), 4, 40, and 400 μg/kg·body weight/day from gestation day 1 through lactation day 21. Spatial learning was evaluated using the Morris water maze on postnatal day 22. Expression levels of NMDARs were determined using real-time polymerase chain reaction and Western blot. The results showed that male offspring exposed to BPA exhibited increased latency in reaching the platform and reduced time in the target quadrant, and the number of crossing the platform was less, as compared with the control group. The mRNA and protein expression levels of NMDARs in the hippocampus were significantly downregulated when compared with the control group of male offspring. The data showed that maternal exposure to BPA at low dosage can cause cognitive deficits in male rat offspring, probably due to a decrease in NMDARs in the hippocampus.

Sex-biased impact of endocrine disrupting chemicals on behavioral development and vulnerability to disease: Of mice and children

Sex is a fundamental biological characteristic that influences many aspects of an organism's phenotype, including neurobiological functions and behavior as a result of species-specific evolutionary pressures. Sex differences have strong implications for vulnerability to disease and susceptibility to environmental perturbations. Endocrine disrupting chemicals (EDCs) have the potential to interfere with sex hormones functioning and influence development in a sex specific manner. Here we present an updated descriptive review of findings from animal models and human studies regarding the current evidence for altered sex-differences in behavioral development in response to early exposure to EDCs, with a focus on bisphenol A and phthalates. Overall, we show that animal and human studies have a good degree of consistency and that there is strong evidence demonstrating that EDCs exposure during critical periods of development affect sex differences in emotional and cognitive behaviors. Results are more heterogeneous when social, sexual and parental behaviors are considered. In order to pinpoint sex differences in environmentally-driven disease vulnerabilities, researchers need to consider sex-biased developmental effects of EDCs.

The Use and Misuse of Historical Controls in Regulatory Toxicology: Lessons from the CLARITY-BPA Study

For many endocrine-disrupting chemicals (EDCs) including Bisphenol A (BPA), animal studies show that environmentally relevant exposures cause harm; human studies are consistent with these findings. Yet, regulatory agencies charged with protecting public health continue to conclude that human exposures to these EDCs pose no risk. One reason for the disconnect between the scientific consensus on EDCs in the endocrinology community and the failure to act in the regulatory community is the dependence of the latter on so-called "guideline studies" to evaluate hazards, and the inability to incorporate independent scientific studies in risk assessment. The Consortium Linking Academic and Regulatory Insights on Toxicity (CLARITY) study was intended to bridge this gap, combining a "guideline" study with independent hypothesis-driven studies designed to be more appropriate to evaluate EDCs. Here we examined an aspect of "guideline" studies, the use of so-called "historical controls," which are essentially control data borrowed from prior studies to aid in the interpretation of current findings. The US Food and Drug Administration authors used historical controls to question the plausibility of statistically significant BPA-related effects in the CLARITY study. We examined the use of historical controls on 5 outcomes in the CLARITY "guideline" study: mammary neoplasms, pituitary neoplasms, kidney nephropathy, prostate inflammation and adenomas, and body weight. Using US Food and Drug Administration-proposed historical control data, our evaluation revealed that endpoints used in "guideline" studies are not as reproducible as previously held. Combined with other data comparing the effects of ethinyl estradiol in 2 "guideline" studies including CLARITY-BPA, we conclude that near-exclusive reliance on "guideline" studies can result in scientifically invalid conclusions.

Potentiation of the Glycine Response by Bisphenol A, an Endocrine Disrupter, on the Substantia Gelatinosa Neurons of the Trigeminal Subnucleus Caudalis in Mice

Lamina II, also called the substantia gelatinosa (SG) of the medullary dorsal horn (the trigeminal subnucleus caudalis, Vc), is thought to play an essential role in the control of orofacial nociception because it receives the nociceptive signals from primary afferents, including thin myelinated Aδ- and unmyelinated C-fibers. Glycine, the main inhibitory neurotransmitter in the central nervous system, plays an essential role in the transference of nociceptive messages from the periphery to higher brain regions. Bisphenol A (BPA) is reported to alter the morphological and functional characteristics of neuronal cells and to be an effector of a great number of ion channels in the central nervous system. However, the electrophysiological effects of BPA on the glycine receptors of SG neurons in the Vc have not been well studied. Therefore, in this study, we used the whole-cell patch-clamp technique to determine the effect of BPA on the glycine response in SG neurons of the Vc in male mice. We demonstrated that in early neonatal mice (0-3 postnatal day mice), BPA did not affect the glycine-induced inward current. However, in the juvenile and adult groups, BPA enhanced the glycine-mediated responses. Heteromeric glycine receptors were involved in the modulation by BPA. The interaction between BPA and glycine appears to have a significant role in regulating transmission in the nociceptive pathway.

Review of the Effects of Perinatal Exposure to Endocrine-Disrupting Chemicals in Animals and Humans

Maternal exposure to endocrine-disrupting chemicals (EDCs) is associated with long-term hormone-dependent effects that are sometimes not revealed until maturity, middle age, or adulthood. The aim of this study was to conduct descriptive reviews on animal experimental and human epidemiological evidence of the adverse health effects of in utero and lactational exposure to selected EDCs on the first generation and subsequent generation of the exposed offspring. PubMed, Web of Science, and Toxline databases were searched for relevant human and experimental animal studies on 29 October 29 2018. Search results were screened for relevance, and studies that met the inclusion criteria were evaluated and qualitative data extracted for analysis. The search yielded 73 relevant human and 113 animal studies. Results from studies show that in utero and lactational exposure to EDCs is associated with impairment of reproductive, immunologic, metabolic, neurobehavioral, and growth physiology of the exposed offspring up to the fourth generation without additional exposure. Little convergence is seen between animal experiments and human studies in terms of the reported adverse health effects which might be associated with methodologic challenges across the studies. Based on the available animal and human evidence, in utero and lactational exposure to EDCs is detrimental to the offspring. However, more human studies are necessary to clarify the toxicological and pathophysiological mechanisms underlying these effects.

Endocrine disruptors and the future of toxicology testing - lessons from CLARITY-BPA

Five years ago, an ambitious collaboration, the Consortium Linking Academic and Regulatory Insights on Toxicity of BPA (CLARITY-BPA; henceforth CLARITY), was launched by three US agencies. The goal was to provide a definitive evaluation of bisphenol A (BPA) and explain disparities between traditional regulatory studies and findings from independent investigators. BPA or vehicle-treated rats from an FDA facility were used in a guideline study and animals and/or tissues were provided to academic researchers for analysis. An interim summary released in February 2018 by the FDA concluded that currently authorized uses of BPA continue to be safe. We disagree. In this Perspectives, we summarize the goals, design and problems of CLARITY. We conclude that, despite its flaws, CLARITY provides important insight and, taken together, the data provide compelling evidence that low-dose BPA exposure induces marked adverse effects. Indeed, the greatest number of effects were observed at doses 20,000 times lower than the current 'safe' dose of BPA for humans.

Effects of Bauhinia forficata on glycaemia, lipid profile, hepatic glycogen content and oxidative stress in rats exposed to Bisphenol A

Bisphenol A (BPA) is an abundant raw material applied in the production of daily necessities, such as food cans, baby bottles, electronic and medical equipment. Phytotherapeutic use of plant preparations has long been known for multiple target medicinal uses. The species Bauhinia forficata is widely used as hypoglycemic, anti-inflammatory, antioxidant, diuretic and hypocholesterolemic agent. The aim of this study was to verify the effects of B. forficata extract in association with BPA exposure on serological parameters, hepatic antioxidant status and glycogen store capacity in Wistar rats. B. forficata was able to reduce BPA-induced glucose levels; it also prevented the early glucose elevation in control and BPA-exposed animals after the glucose provocative test. This effect was related to the hepatic glycogen content; while BPA reduced the hepatic glycogen deposits B. forficata treatment contributed to minimize it. BPA and B. forficata singly caused elevation in triacylglycerol and VLDL levels and reduction in cholesterol and LDL concentrations. BPA increased hepatic malondialdehyde levels and reduced catalase activity, thus inducing liver oxidative stress. Conversely, B. forficata treatment reduced malondialdehyde concentration without interfering with catalase activity; this antioxidant capacity is attributed to the flavonoids content (e.g., kaempferol and myricetin). Based on these results, we demonstrated that B. forficata commercial extract has hypoglycemic and antioxidant properties capable of minimizing the effects of BPA. However, it should be considered that the consumption of herbal commercial extract must be judicious to avoid deleterious health effects.

Flaws in design, execution and interpretation limit CLARITY-BPA's value for risk assessments of bisphenol A

The Consortium Linking Academic and Regulatory Insights on BPA Toxicity (CLARITY-BPA) involved the Food and Drug Administration, the National Toxicology Program and 14 academic investigators funded by the National Institute of Environmental Health Sciences. Two key questions to be answered by CLARITY-BPA were as follows: (1) Would the academic investigator studies show effects at low doses of bisphenol A (BPA) while the core guideline study conducted by the FDA only showed toxic effects at high doses? (2) Would the academic investigators be able to replicate their numerous prior studies with animals raised and treated in the FDA's toxicology centre? Several flaws in the design and execution of CLARITY-BPA biased the experiment towards not finding significant results (Type 2 error): (1) use of the oestrogen-insensitive NCTR CD-SD rat, (2) use of a stressful daily gavage BPA administration procedure throughout life, (3) lack of inclusion of non-gavaged negative controls and (4) lack of a comprehensive examination of animals for BPA contamination. In spite of these flaws, in some of the experiments conducted by CLARITY-BPA academic investigators, and also in the FDA's core study, there were significant low-dose effects, but these were ignored by the FDA. Thus, immediately after releasing the results from their core portion of CLARITY-BPA, the FDA issued a statement concluding BPA was "safe," and they ignored non-monotonic dose-response relationships. The FDA should not base its BPA risk assessment only on outdated guideline studies, but instead on the vast (~8000) number of publications documenting the similar health hazards BPA poses to animals and humans.

Impairment of learning and memory performances induced by BPA: Evidences from the literature of a MoA mediated through an ED

Many rodent studies and a few non-human primate data report impairments of spatial and non-spatial memory induced by exposure to bisphenol A (BPA), which are associated with neural modifications, particularly in processes involved in synaptic plasticity. BPA-induced alterations involve disruption of the estrogenic pathway as established by reversal of BPA-induced effects with estrogenic receptor antagonist or by interference of BPA with administered estradiol in ovariectomized animals. Sex differences in hormonal impregnation during critical periods of development and their influence on maturation of learning and memory processes may explain the sexual dimorphism observed in BPA-induced effects in some studies. Altogether, these data highly support the plausibility that alteration of learning and memory and synaptic plasticity by BPA is essentially mediated by disturbance of the estrogenic pathways. As memory function in humans involves similar signaling pathways, this mode of action of BPA has the potential to alter human cognitive abilities.

CLARITY-BPA academic laboratory studies identify consistent low-dose Bisphenol A effects on multiple organ systems

Bisphenol A (BPA) is a high-production chemical used in a variety of applications worldwide. While BPA has been documented as an endocrine-disrupting chemical (EDC) having adverse health-related outcomes in multiple studies, risk assessment for BPA has lagged due to reliance on guideline toxicology studies over academic ones with end-points considered more sensitive and appropriate. To address current controversies on BPA safety, the United States National Institute of Environmental Health Sciences (NIEHS), the National Toxicology Program (NTP) and the Food and Drug Administration (FDA) established the Consortium Linking Academic and Regulatory Insights on BPA Toxicity (CLARITY-BPA) using the NCTR Sprague-Dawley rats. The goal of CLARITY-BPA is to perform a traditional regulatory toxicology study (Core study) in conjunction with multiple behavioural, molecular and cellular studies by academic laboratories focused on previously identified BPA-sensitive organ systems (Academic studies). Combined analysis of the data from both study types will be undertaken by the NTP with the aim of resolving uncertainties on BPA toxicity. To date, the Core study has been completed and a draft report released. Most of the academic studies have also been finalized and published in peer-reviewed journals. In light of this important milestone, the PPTOX-VI meeting held in the Faroe Islands, 27-30 May 2018 devoted a plenary session to CLARITY-BPA with presentations by multiple investigators with the purpose of highlighting key outcome. This MiniReview synthesizes the results of three academic studies presented at this plenary session, evaluates recently published findings by other CLARITY-BPA academic studies to provide an early combined overview of this emerging data and places this in the context of the Core study findings. This co-ordinated effort revealed a plethora of significant BPA effects across multiple organ systems and BPA doses with non-monotonic responses across the dose range utilized. Remarkably consistent across most studies, including the Core study, are low-dose effects (2.5, 25 and 250 μg BPA/kg body-weight). Collectively, the findings highlighted herein corroborate a significant body of evidence that documents adverse effects of BPA at doses relevant to human exposures and emphasizes the need for updated risk assessment analysis.

Ameliorative effect of ginseng extract on phthalate and bisphenol A reprotoxicity during pregnancy in rats

Phthalates (such as DEHP) and bisphenol A (BPA) are widely used chemicals in plastics manufacturing and exert public health concerns as endocrine disrupters. This study was designed to investigate the deleterious effect of DEHP and BPA on endocrine profile of pregnant female rats and the combined treatment with ginseng extract (Panax ginseng). Seventy-two pregnant rats were divided into six groups (control, ginseng, DEHP, BPA, Gin + DEHP, and Gin + BPA), 12 females per each group. The drugs were supplemented from pregnancy day 0 until day 20. Determination of serum sex hormones (testosterone, progesterone, and estradiol) were determined on days 4, 10, and 20 of pregnancy. mRNA transcripts of STAR, HSD17B3, CYP17, AKT1, and PTEN were relatively quantified against ACTB in the ovary and placenta of days 10 and 20 pregnant females by relative quantitative polymerase-chain reaction (RQ-PCR). DEHP and BPA significantly decreased the endocrine profile of testosterone, progesterone, and estradiol of days 10 and 20 of pregnant females. Combined administration of these chemicals along with ginseng extracts has returned the hormones to normal levels when compared with the control group. The ovarian and placental CYP17 and HSD17B3 mRNA transcripts showed variable expression pattern in both tissues and they were significantly affected by DEHP and BPA administration, concomitantly correlating to STAR, AKT1, PTEN, progesterone, and testosterone levels on pregnancy days 10 and 20. The results confirm the reprotoxicity of DEHP and BPA as endocrine disruptors and indicate that ginseng could be used to alleviate the toxic effects of these chemicals.

DNA methylation and copy number variation analyses of human embryonic stem cell-derived neuroprogenitors after low-dose decabromodiphenyl ether and/or bisphenol A exposure

The polybrominated diphenyl ether flame retardants decabromodiphenyl ether (BDE-209) and bisphenol A (BPA) are environmental contaminants that can cross the placenta and exert toxicity in the developing fetal nervous system. Copy number variants (CNVs) play a role in a number of genetic disorders and may be implicated in BDE-209/BPA teratogenicity. In this study, we found that BDE-209 and/or BPA exposure decreased neural differentiation efficiency of human embryonic stem cells (hESCs), although there was a >90% induction of neuronal progenitor cells (NPCs) from exposed hESCs. However, the mean of CNV numbers in the NPCs with BDE-209 + BPA treatment was significantly higher compared to the other groups, whereas DNA methylation was lower and DNA methyltransferase(DNMT1 and DNMT3A) expression were significantly decreased in all of the BDE-209 and/or BPA treatment groups compared with the control groups. The number of CNVs in chromosomes 3, 4, 11, 22, and X in NPCs with BDE-209 and/or BPA exposure was higher compared to the control group. In addition, CNVs in chromosomes 7, 8, 14, and 16 were stable in hESCs and hESCs-derived NPCs irrespective of BDE-209/BPA exposure, and CNVs in chromosomes 20 q11.21 and 16 p13.11 might be induced by neural differentiation. Thus, BDE-209/BPA exposure emerges as a potential source of CNVs distinct from neural differentiation by itself. BDE-209 and/or BPA exposure may cause genomic instability in cultured stem cells via reduced activity of DNA methyltransferase, suggesting a new mechanism of human embryonic neurodevelopmental toxicity caused by this class of environmental toxins.

Prenatal exposure to bisphenol A and hyperactivity in children: a systematic review and meta-analysis

BACKGROUND

Attention-deficit hyperactivity disorder (ADHD) has increased in prevalence in the past decade. Studies attempting to identify a specific genetic component have not been able to account for much of the heritability of ADHD, indicating there may be gene-environment interactions underlying the disorder, including early exposure to environmental chemicals. Based on several relevant studies, we chose to examine bisphenol A (BPA) as a possible contributor to ADHD in humans. BPA is a widespread environmental chemical that has been shown to disrupt neurodevelopment in rodents and humans.

OBJECTIVES

Using the Office of Health Assessment and Translation (OHAT) framework, a systematic review and meta-analysis was designed to determine the relationship between early life exposure to BPA and hyperactivity, a key diagnostic criterion of ADHD.

DATA SOURCES

Searches of PubMed, Web of Science, and Toxline were completed for all literature to January 1, 2017.

STUDY ELIGIBILITY CRITERIA

For inclusion, the studies had to publish original data, be in the English language, include a measure of BPA exposure, and assess if BPA exposure affected hyperactive behaviors in mice, rats or humans. Exposure to BPA had to occur at <3 months of age for humans, up to postnatal day 35 for rats and up to postnatal day 40 for mice. Exposure could occur either gestationally (via maternal exposure) or directly to the offspring.

STUDY APPRAISAL AND SYNTHESIS METHODS

Studies were evaluated using the OHAT risk of bias tool. The effects in humans were assessed qualitatively. For rodents exposed to 20 μg/kg/day BPA, we evaluated the study findings in a random effects meta-analytical model.

RESULTS

A review of the literature identified 29 rodent and 3 human studies. A random effects meta-analysis showed significantly increased hyperactivity in male rodents. In humans, early BPA exposure was associated with hyperactivity in boys and girls.

LIMITATIONS, CONCLUSIONS, AND IMPLICATIONS OF KEY FINDINGS

We concluded that early life BPA exposure is a presumed human hazard for the development of hyperactivity. Possible limitations of this systematic review include deficiencies in author reporting, exclusion of some literature based on language, and insufficient similarity between human studies. SRs that result in hazard-based conclusions are the first step in assessing and mitigating risks. Given the widespread exposure of BPA and increasing diagnoses of ADHD, we recommend immediate actions to complete such risk analyses and take next steps for the protection of human health. In the meantime, precautionary measures should be taken to reduce exposure in pregnant women, infants and children. The present analysis also discusses potential mechanisms by which BPA affects hyperactivity, and the most effective avenues for future research.

SYSTEMATIC REVIEW REGISTRATION NUMBER

Not available.

Healing potential of Adiantum capillus-veneris L. plant extract on bisphenol A-induced hepatic toxicity in male albino rats

Bisphenol A (BPA) is a widely used environmental pollutant in the production of plastics but causes hepatotoxicity in mammals. In the present study, we studied the BPA-induced oxidative stress in rats and ameliorative potential of Adiantum capillus-veneris L. plant. It was concluded that the BPA can reduce the body and liver weight, increase in biochemical levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST), total bilirubin, and disturb the normal hepatic physiology, histology, and metabolism. Additionally, liver histology shows hepatic necrosis, congestion, and vacuolization in exposed individuals. In contrast, simultaneous exposure of A. capillus-veneris and BPA showed declining trend in serum biomarker levels and normal histopathological structures. We conclude that the A. capillus-veneris plant is antioxidant in nature and can reduce the BPA-induced toxicity. These findings are very helpful to understand the BPA-induced hepatic toxicity and ameliorative potential of A. capillus-veneris plant and are of great importance in risk assessment of xenobiotics.

Water Quality and Brain Function

In the United States, regulations are in place to ensure the quality of drinking water. Such precautions are intended to safeguard the health of the population. However, regulatory guidelines may at times fail to achieve their purpose. This may be due to lack of sufficient data regarding the health hazards of chronic low dose exposure to contaminants or the introduction of new substances that pose a health hazard risk that has yet to be identified. In this review, examples of different sources of contaminants in drinking water will be discussed, followed by an evaluation of some select individual toxicants with known adverse neurological impact. The ability of mixtures to potentially cause additive, synergistic, or antagonistic neurotoxic responses will be briefly addressed. The last section of the review will provide examples of select mechanisms by which different classes of contaminants may lead to neurological impairments. The main objective of this review is to bring to light the importance of considering trace amounts of chemicals in the drinking water and potential brain abnormalities. There is continued need for toxicology studies to better understand negative consequences of trace amounts of toxins and although it is beyond the scope of this brief overview it is hoped that the review will underscore the paucity of studies focused on determining how long-term exposure to minute levels of contaminants in drinking water may pose a significant health hazard.

Recommendations for harmonization of data collection and analysis of developmental neurotoxicity endpoints in regulatory guideline studies: Proceedings of workshops presented at Society of Toxicology and joint Teratology Society and Neurobehavioral Teratology Society meetings

The potential for developmental neurotoxicity (DNT) of environmental chemicals may be evaluated using specific test guidelines from the US Environmental Protection Agency or the Organisation for Economic Cooperation and Development (OECD). These guidelines generate neurobehavioral, neuropathological, and morphometric data that are evaluated by regulatory agencies globally. Data from these DNT guideline studies, or the more recent OECD extended one-generation reproductive toxicity guideline, play a pivotal role in children's health risk assessment in different world areas. Data from the same study may be interpreted differently by regulatory authorities in different countries resulting in inconsistent evaluations that may lead to inconsistencies in risk assessment decisions internationally, resulting in regional differences in public health protection or in commercial trade barriers. These issues of data interpretation and reporting are also relevant to juvenile and pre-postnatal studies conducted more routinely for pharmaceuticals and veterinary medicines. There is a need for development of recommendations geared toward the operational needs of the regulatory scientific reviewers who apply these studies in risk assessments, as well as the scientists who generate DNT data sets. The workshops summarized here draw upon the experience of the authors representing government, industry, contract research organizations, and academia to discuss the scientific issues that have emerged from diverse regulatory evaluations. Although various regulatory bodies have different risk management decisions and labeling requirements that are difficult to harmonize, the workshops provided an opportunity to work toward more harmonized scientific approaches for evaluating DNT data within the context of different regulatory frameworks. Five speakers and their coauthors with neurotoxicology, neuropathology, and regulatory toxicology expertise discussed issues of variability, data reporting and analysis, and expectations in DNT data that are encountered by regulatory authorities. In addition, principles for harmonized evaluation of data were suggested using guideline DNT data as case studies.

Derivation of an oral Maximum Allowable Dose Level for Bisphenol A

Bisphenol A (BPA) is a high production volume chemical that is used in plastics and epoxy coatings. In 2015, California's Office of Environmental Health Hazard Assessment (OEHHA) added BPA to the Proposition 65 list of chemicals "known to cause reproductive toxicity" based on its Developmental and Reproductive Toxicant Identification Committee's (DART-IC) conclusion that BPA has been shown to cause female reproductive toxicity. A critical factor in determining compliance with Proposition 65 is a Maximum Allowable Dose Level (MADL), which is the exposure level at which a chemical would have no observable reproductive effect even if a person were exposed to 1000 times that level. We performed a comprehensive review of the literature, including the studies reviewed by DART-IC, and derived an oral MADL. Of all the studies we identified, Delclos et al. (2014) is of sufficient quality, has the lowest no observed effect level (NOEL), and results in the most conservative MADL of 157 μg/d. This is generally supported by other studies, including those that were considered by DART-IC. Also, the oral MADL provides a similar margin of safety as OEHHA's dermal MADL and other regulatory guidelines. Taken together, the scientific data support an oral MADL of 157 μg/d.

Estrogenic Endocrine Disrupting Chemicals Influencing NRF1 Regulated Gene Networks in the Development of Complex Human Brain Diseases

During the development of an individual from a single cell to prenatal stages to adolescence to adulthood and through the complete life span, humans are exposed to countless environmental and stochastic factors, including estrogenic endocrine disrupting chemicals. Brain cells and neural circuits are likely to be influenced by estrogenic endocrine disruptors (EEDs) because they strongly dependent on estrogens. In this review, we discuss both environmental, epidemiological, and experimental evidence on brain health with exposure to oral contraceptives, hormonal therapy, and EEDs such as bisphenol-A (BPA), polychlorinated biphenyls (PCBs), phthalates, and metalloestrogens, such as, arsenic, cadmium, and manganese. Also we discuss the brain health effects associated from exposure to EEDs including the promotion of neurodegeneration, protection against neurodegeneration, and involvement in various neurological deficits; changes in rearing behavior, locomotion, anxiety, learning difficulties, memory issues, and neuronal abnormalities. The effects of EEDs on the brain are varied during the entire life span and far-reaching with many different mechanisms. To understand endocrine disrupting chemicals mechanisms, we use bioinformatics, molecular, and epidemiologic approaches. Through those approaches, we learn how the effects of EEDs on the brain go beyond known mechanism to disrupt the circulatory and neural estrogen function and estrogen-mediated signaling. Effects on EEDs-modified estrogen and nuclear respiratory factor 1 (NRF1) signaling genes with exposure to natural estrogen, pharmacological estrogen-ethinyl estradiol, PCBs, phthalates, BPA, and metalloestrogens are presented here. Bioinformatics analysis of gene-EEDs interactions and brain disease associations identified hundreds of genes that were altered by exposure to estrogen, phthalate, PCBs, BPA or metalloestrogens. Many genes modified by EEDs are common targets of both 17 β-estradiol (E2) and NRF1. Some of these genes are involved with brain diseases, such as Alzheimer's Disease (AD), Parkinson's Disease, Huntington's Disease, Amyotrophic Lateral Sclerosis, Autism Spectrum Disorder, and Brain Neoplasms. For example, the search of enriched pathways showed that top ten E2 interacting genes in AD-APOE, APP, ATP5A1, CALM1, CASP3, GSK3B, IL1B, MAPT, PSEN2 and TNF-underlie the enrichment of the Kyoto Encyclopedia of Genes and Genomes (KEGG) AD pathway. With AD, the six E2-responsive genes are NRF1 target genes: APBB2, DPYSL2, EIF2S1, ENO1, MAPT, and PAXIP1. These genes are also responsive to the following EEDs: ethinyl estradiol (APBB2, DPYSL2, EIF2S1, ENO1, MAPT, and PAXIP1), BPA (APBB2, EIF2S1, ENO1, MAPT, and PAXIP1), dibutyl phthalate (DPYSL2, EIF2S1, and ENO1), diethylhexyl phthalate (DPYSL2 and MAPT). To validate findings from Comparative Toxicogenomics Database (CTD) curated data, we used Bayesian network (BN) analysis on microarray data of AD patients. We observed that both gender and NRF1 were associated with AD. The female NRF1 gene network is completely different from male human AD patients. AD-associated NRF1 target genes-APLP1, APP, GRIN1, GRIN2B, MAPT, PSEN2, PEN2, and IDE-are also regulated by E2. NRF1 regulates targets genes with diverse functions, including cell growth, apoptosis/autophagy, mitochondrial biogenesis, genomic instability, neurogenesis, neuroplasticity, synaptogenesis, and senescence. By activating or repressing the genes involved in cell proliferation, growth suppression, DNA damage/repair, apoptosis/autophagy, angiogenesis, estrogen signaling, neurogenesis, synaptogenesis, and senescence, and inducing a wide range of DNA damage, genomic instability and DNA methylation and transcriptional repression, NRF1 may act as a major regulator of EEDs-induced brain health deficits. In summary, estrogenic endocrine disrupting chemicals-modified genes in brain health deficits are part of both estrogen and NRF1 signaling pathways. Our findings suggest that in addition to estrogen signaling, EEDs influencing NRF1 regulated communities of genes across genomic and epigenomic multiple networks may contribute in the development of complex chronic human brain health disorders.

Adverse effects of bisphenol A (BPA) on the dopamine system in two distinct cell models and corpus striatum of the Sprague-Dawley rat

The aim of this study was to examine the effects of bisphenol A (BPA) on the brain dopamine (DA) system utilizing both in vitro models (GH3 cells, a rat pituitary cell line, and SH-SY5Y cells, a human neuroblastoma cell line) and an animal model such as Sprague-Dawley (SD) rats. First, cellular DA uptake was measured 2 or 8 h following BPA exposure (0.1-400 μM) in SH-SY5Y cells, where a significant increase in DA uptake was noted. BPA exerted no marked effect on dopamine active transporter levels in GH3 cells exposed for 8 or 24 h. However, SH-SY5Y cells displayed an increase in dopamine transporter (DAT) levels following 24 h of exposure to BPA. In contrast to DAT levels, BPA exposure produced no marked effect on DA D1 receptor levels in SH-SY5Y cells, yet a significant decrease in GH3 cells following both 8- and 24-h exposure periods was noted, suggesting that BPA exerts differential effects dependent upon cell type. BPA produced no significant effects on prolactin levels at 2 h, but a marked fall occurred at 24 h of exposure in GH3 cells. Finally, to examine the influence of dietary developmental exposure to BPA on brain DA levels in F1 offspring, SD rats were exposed to BPA (0.5-20 mg/kg) through maternal transfer and/or diet and striatal DA levels were measured on postnatal day (PND) 60 using high-performance liquid chromatography (HPLC). Data demonstrated that chronic exposure to BPA did not significantly alter striatal DA levels in the SD rat.

Low-dose effect of developmental bisphenol A exposure on sperm count and behaviour in rats

Bisphenol A is widely used in food contact materials and other products and is detected in human urine and blood. Bisphenol A may affect reproductive and neurological development; however, opinion of the European Food Safety Authority (EFSA) on bisphenol A (EFSA J, 13, 2015 and 3978) concluded that none of the available studies were robust enough to provide a point of departure for setting a tolerable daily intake for bisphenol A. In the present study, pregnant Wistar rats (n = 17-21) were gavaged from gestation day 7 to pup day 22 with bisphenol A doses of 0, 25 μg, 250 μg, 5 mg or 50 mg/kg bw/day. In the offspring, growth, sexual maturation, weights and histopathology of reproductive organs, oestrus cyclicity and sperm counts were assessed. Neurobehavioural development was investigated using a behavioural testing battery including tests for motor activity, sweet preference, anxiety and spatial learning. Decreased sperm count was found at the lowest bisphenol A dose, that is 25 μg/kg/day, but not at the higher doses. Reproductive organ weight and histology were not affected and no behavioural effects were seen in male offspring. In the female offspring, exposure to 25 μg/kg bw/day bisphenol A dose resulted in increased body weight late in life and altered spatial learning in a Morris water maze, indicating masculinization of the brain. Decreased intake of sweetened water was seen in females from the highest bisphenol A dose group, also a possible sign of masculinization. The other investigated endpoints were not significantly affected. In conclusion, the present study using a robust experimental study design, has shown that developmental exposure to 25 μg/kg bw/day bisphenol A can cause adverse effects on fertility (decreased sperm count), neurodevelopment (masculinization of spatial learning in females) and lead to increased female body weight late in life. These results suggest that the new EFSA temporary tolerable daily intake of 4 μg/kg bw/day is not sufficiently protective with regard to endocrine disrupting effects of bisphenol A in humans.

Impairment of object recognition memory by maternal bisphenol A exposure is associated with inhibition of Akt and ERK/CREB/BDNF pathway in the male offspring hippocampus

Bisphenol A (BPA) is a commonly used endocrine-disrupting chemical used as a component of polycarbonates plastics that has potential adverse effects on human health. Exposure to BPA during development has been implicated in memory deficits, but the mechanism of action underlying the effect is not fully understood. In this study, we investigated the effect of maternal exposure to BPA on object recognition memory and the expressions of proteins important for memory, especially focusing on the ERK/CREB/BDNF pathway. Pregnant Sprague-Dawley female rats were orally treated with either vehicle or BPA (0.05, 0.5, 5 or 50 mg/kg BW/day) during days 9-20 of gestation. Male offspring were tested on postnatal day 21 with the object recognition task. Recognition memory was assessed using the object recognition index (index=the time spent exploring the novel object/(the time spent exploring the novel object+the time spent exploring the familiar object)). In the test session performed 90 min after the training session, BPA-exposed male offspring not only spent more time in exploring the familiar object at the highest dose than the control, but also displayed a significantly decreased the object recognition index at the doses of 0.5, 5 and 50 mg/kg BW/day. During the test session performed 24h after the training session, BPA-treated males did not change the time spent exploring the familiar object, but had a decreased object recognition index at 5 and 50 mg/kg BW/day, when compared to control group. These findings indicate that object recognition memory was susceptible to maternal BPA exposure. Western blot analysis of hippocampi from BPA-treated male offspring revealed a decrease in Akt, phospho-Akt, p44/42 MAPK and phospho-p44/42 MAPK protein levels, compared to controls. In addition, BPA significantly inhibited the levels of phosphorylation of CREB and BDNF in the hippocampus. Our results show that maternal BPA exposure may full impair object recognition memory, and that impairment may be related to a decrease in Akt activation and an inhibition of the ERK/CREB/BDNF pathway in the hippocampus. This study also adds new evidence that suggests BPA has an antagonistic effect on the action of estrogen in the brain.

Repeated exposure to neurotoxic levels of chlorpyrifos alters hippocampal expression of neurotrophins and neuropeptides

Chlorpyrifos (CPF), an organophosphorus pesticide (OP), is one of the most widely used pesticides in the world. Subchronic exposures to CPF that do not cause cholinergic crisis are associated with problems in cognitive function (i.e., learning and memory deficits), but the biological mechanism(s) underlying this association remain speculative. To identify potential mechanisms of subchronic CPF neurotoxicity, adult male Long Evans (LE) rats were administered CPF at 3 or 10mg/kg/d (s.c.) for 21 days. We quantified mRNA and non-coding RNA (ncRNA) expression profiles by RNA-seq, microarray analysis and small ncRNA sequencing technology in the CA1 region of the hippocampus. Hippocampal slice immunohistochemistry was used to determine CPF-induced changes in protein expression and localization patterns. Neither dose of CPF caused overt clinical signs of cholinergic toxicity, although after 21 days of exposure, cholinesterase activity was decreased to 58% or 13% of control levels in the hippocampus of rats in the 3 or 10mg/kg/d groups, respectively. Differential gene expression in the CA1 region of the hippocampus was observed only in the 10mg/kg/d dose group relative to controls. Of the 1382 differentially expressed genes identified by RNA-seq and microarray analysis, 67 were common to both approaches. Differential expression of six of these genes (Bdnf, Cort, Crhbp, Nptx2, Npy and Pnoc) was verified in an independent CPF exposure study; immunohistochemistry demonstrated that CRHBP and NPY were elevated in the CA1 region of the hippocampus at 10mg/kg/d CPF. Gene ontology enrichment analysis suggested association of these genes with receptor-mediated cell survival signaling pathways. miR132/212 was also elevated in the CA1 hippocampal region, which may play a role in the disruption of neurotrophin-mediated cognitive processes after CPF administration. These findings identify potential mediators of CPF-induced neurobehavioral deficits following subchronic exposure to CPF at a level that inhibits hippocampal cholinesterase to less than 20% of control. An equally significant finding is that subchronic exposure to CPF at a level that produces more moderate inhibition of hippocampal cholinesterase (approximately 50% of control) does not produce a discernable change in gene expression.

EDC-2: The Endocrine Society's Second Scientific Statement on Endocrine-Disrupting Chemicals

The Endocrine Society's first Scientific Statement in 2009 provided a wake-up call to the scientific community about how environmental endocrine-disrupting chemicals (EDCs) affect health and disease. Five years later, a substantially larger body of literature has solidified our understanding of plausible mechanisms underlying EDC actions and how exposures in animals and humans-especially during development-may lay the foundations for disease later in life. At this point in history, we have much stronger knowledge about how EDCs alter gene-environment interactions via physiological, cellular, molecular, and epigenetic changes, thereby producing effects in exposed individuals as well as their descendants. Causal links between exposure and manifestation of disease are substantiated by experimental animal models and are consistent with correlative epidemiological data in humans. There are several caveats because differences in how experimental animal work is conducted can lead to difficulties in drawing broad conclusions, and we must continue to be cautious about inferring causality in humans. In this second Scientific Statement, we reviewed the literature on a subset of topics for which the translational evidence is strongest: 1) obesity and diabetes; 2) female reproduction; 3) male reproduction; 4) hormone-sensitive cancers in females; 5) prostate; 6) thyroid; and 7) neurodevelopment and neuroendocrine systems. Our inclusion criteria for studies were those conducted predominantly in the past 5 years deemed to be of high quality based on appropriate negative and positive control groups or populations, adequate sample size and experimental design, and mammalian animal studies with exposure levels in a range that was relevant to humans. We also focused on studies using the developmental origins of health and disease model. No report was excluded based on a positive or negative effect of the EDC exposure. The bulk of the results across the board strengthen the evidence for endocrine health-related actions of EDCs. Based on this much more complete understanding of the endocrine principles by which EDCs act, including nonmonotonic dose-responses, low-dose effects, and developmental vulnerability, these findings can be much better translated to human health. Armed with this information, researchers, physicians, and other healthcare providers can guide regulators and policymakers as they make responsible decisions.

Modulatory effects of dietary inclusion of garlic (Allium sativum) on gentamycin-induced hepatotoxicity and oxidative stress in rats

OBJECTIVE

To investigate the ameliorative effect of dietary inclusion of garlic (Allium sativum) on gentamycin-induced hepatotoxicity in rats.

METHODS

Adult male rats were randomly divided into four groups with six animals in each group. Groups 1 and 2 were fed basal diet while Groups 3 and 4 were fed diets containing 2% and 4% garlic respectively for 27 d prior to gentamycin administration. Hepatotoxicity was induced by the intraperitoneal administration of gentamycin (100 mg/kg body weight) for 3 d. The liver and plasma were studied for hepatotoxicity and antioxidant indices.

RESULTS

Gentamycin induces hepatic damage as revealed by significant (P<0.05) elevation of liver damage marker enzymes (aspartate transaminase and alanine aminotransferase) and reduction in plasma albumin level. Gentamycin also caused a significant (P<0.05) alteration in plasma and liver enzymatic (catalase, glutathione and super oxygen dehydrogenises) and non-enzymatic (glutathione and vitamin C) antioxidant indices with concomitant increase in the malondialdehyde content; however, there was a significant (P<0.05) restoration of the antioxidant status coupled with significant (P<0.05) decrease in the tissues' malondialdehyde content, following consumption of diets containing garlic.

CONCLUSIONS

These results suggest that dietary inclusion of garlic powder could protect against gentamycin-induced hepatotoxicity, improve antioxidant status and modulate oxidative stress; a function attributed to their phenolic constituents.

Perinatal exposure to bisphenol-A impairs spatial memory through upregulation of neurexin1 and neuroligin3 expression in male mouse brain

Bisphenol-A (BPA), a well known endocrine disruptor, impairs learning and memory in rodents. However, the underlying molecular mechanism of BPA induced impairment in learning and memory is not well known. As synaptic plasticity is the cellular basis of memory, the present study investigated the effect of perinatal exposure to BPA on the expression of synaptic proteins neurexin1 (Nrxn1) and neuroligin3 (Nlgn3), dendritic spine density and spatial memory in postnatal male mice. The pregnant mice were orally administered BPA (50 µg/kgbw/d) from gestation day (GD) 7 to postnatal day (PND) 21 and sesame oil was used as a vehicle control. In Morris water maze (MWM) test, BPA extended the escape latency time to locate the hidden platform in 8 weeks male mice. RT-PCR and Immunoblotting results showed significant upregulation of Nrxn1 and Nlgn3 expression in both cerebral cortex and hippocampus of 3 and 8 weeks male mice. This was further substantiated by in-situ hybridization and immunofluorescence techniques. BPA also significantly increased the density of dendritic spines in both regions, as analyzed by rapid Golgi staining. Thus our data suggest that perinatal exposure to BPA impairs spatial memory through upregulation of expression of synaptic proteins Nrxn1 and Nlgn3 and increased dendritic spine density in cerebral cortex and hippocampus of postnatal male mice.

Bisphenol-A impairs myelination potential during development in the hippocampus of the rat brain

Myelin is the functional implication of oligodendrocytes (OLs), which is involved in insulation of axons and promoting rapid propagation of action potential in the brain. OLs are derived from oligodendrocyte progenitor cells (OPCs), which proliferate, differentiate, and migrate throughout the central nervous system. Defects in myelination process lead to the onset of several neurological and neurodegenerative disorders. Exposure to synthetic xenoestrogen bisphenol-A (BPA) causes cognitive dysfunction, impairs hippocampal neurogenesis, and causes onset of neurodevelopmental disorders. However, the effects of BPA on OPC proliferation, differentiation and myelination, and associated cellular and molecular mechanism(s) in the hippocampus of the rat brain are still largely unknown. We found that BPA significantly decreased bromodeoxyuridine (BrdU)-positive cell proliferation and number and size of oligospheres. We observed reduced co-localization of BrdU with myelination markers CNPase and platelet-derived growth factor receptor-α (PDGFR-α), suggesting impaired proliferation and differentiation of OPCs by BPA in culture. We studied the effects of BPA exposure during prenatal and postnatal periods on cellular and molecular alteration(s) in the myelination process in the hippocampus region of the rat brain at postnatal day 21 and 90. BPA exposure both in vitro and in vivo altered proliferation and differentiation potential of OPCs and decreased the expression of genes and levels of proteins that are involved in myelination. Ultrastructural electron microscopy analysis revealed that BPA exposure caused decompaction of myelinated axons and altered g-ratio at both the developmental periods as compared to control. These results suggest that BPA exposure both during prenatal and postnatal periods alters myelination in the hippocampus of the rat brain leading to cognitive deficits.

Abbreviated assessment of bisphenol A toxicology literature

Bisphenol A (BPA), synthesized in 1891, is produced in quantities of >2 million metric tons annually for polycarbonate plastics, epoxy resins and food contact applications. BPA can be a weak estrogen mimic, and is ubiquitous in humans (in 93% US population; in 96% US pregnant women). European/US food/drug agencies conclude that current BPA levels present no risk to the general population (some include infants/children); basic endocrine disruption (ED) researchers state that entire populations are at risk from these levels. The US Food and Drug Administration banned BPA in baby bottles in 2012 'not based on safety concerns'; the US Environmental Protection Agency and its UK counterpart concurred. Basic ED researchers report reproductive/developmental effects from perinatal BPA exposure in mice at very low doses, e.g. 2 ng/g body weight (0.002 mg/kg body weight), with non-monotonic dose-response (NMDR) curves, using few animals per group and few groups; contract research organizations, in good laboratory practice- and guideline-compliant large studies in rats and mice, report no low-dose effects or NMDR curves. The argument rages!

Bisphenol A does not affect memory performance in adult male rats

Bisphenol A (BPA) is an estrogenic endocrine disruptor used for producing polycarbonate plastics and epoxy resins. This study investigated the effects of oral BPA administration on memory performance, general activity, and emotionality in adult male Sprague Dawley rats using a battery of behavioral tests, including an appetite-motivated maze test (MAZE test) used to assess spatial memory performance. In addition, in order to confirm the effects of BPA on spatial memory performance, we examined whether intrahippocampal injection of BPA affects spatial memory consolidation. In the MAZE test, although oral BPA administration at 10 mg/kg significantly altered the number of entries into the incorrect area compared to those of vehicle-treated rats, male rats given BPA through either oral administration or intrahippocampal injection failed to show significant differences in latencies to reach the reward. Also, oral BPA administration did not affect fear-motivated memory performance in the step-through passive avoidance test. Oral BPA administration at 0.05 mg/kg, the lowest dose used in this study, was correlated with a decrease in locomotor activity in the open-field test, whereas oral administration at 10 mg/kg, the highest dose used in this study, was correlated with a light anxiolytic effect in the elevated plus-maze test. The present study suggests that BPA in adulthood has little effect on spatial memory performance in male rats.

Bisphenol A--sources, toxicity and biotransformation

Bisphenol A (BPA) is a chemical compound used in massive amounts in the production of synthetic polymers and thermal paper. In this review, the sources of BPA, which influence its occurrence in the environment and human surrounding will be presented. Data concerning BPA occurrence in food, water and indoor environments as well as its appearance in tissues and body fluids of human body will be shown. The results of in vitro and in vivo studies and the results of epidemiological surveys showing toxic, endocrine, mutagenic and cancerogenic action of BPA will also be discussed. Moreover, data suggesting that exposure of human to BPA may elevate risk of obesity, diabetes and coronary heart diseases will be presented. Finally, biotransformation of BPA in animals, plants and microorganisms (bacteria, fungi, algae), resulting in the formation of various metabolites that exhibit different from BPA toxicity will be described.