Corticosterone-regulated actions in the rat brain are affected by perinatal exposure to low dose of bisphenol A

Centella asiatica improves memory and executive function in middle-aged rats by controlling oxidative stress and cholinergic transmission

ETHNOPHARMACOLOGICAL RELEVANCE

Centella asiatica (L.) Urban, is a medicinal herb with rich history of traditional use in Indian subcontinent. This herb has been valued for its diverse range of medicinal properties including memory booster, and also as a folk treatment for skin diseases, wound healing and mild diuretic.

AIM OF STUDY

Aging is a gradual and continuous process of natural decay in the biological systems, including the brain. This work aims to evaluate the effectiveness of ethanolic extract of Centella asiatica (CAE) on age-associated cognitive impairments in rats, as well as the underlying mechanism.

MATERIAL AND METHODS

Rats were allocated into five distinct groups of 5 animals each: Young rats (3 months old rats), middle-aged (m-aged) rats (13-14 months old), and the remaining three groups were comprised of m-aged rats treated with different concentrations of CAE, viz., 150, 300, and 450 mg/kg b. w., orally for 42 days. Y-maze, open field, novel object recognition, and elevated plus maze tests were used to assess animal behavior. The malondialdehyde (MDA), superoxide dismutase (SOD), and acetylcholinesterase (AChE) assays; and H&E staining were done in the rat brain to assess the biochemical and structural changes. CAE was also subjected to HPLC analysis, in vitro antioxidant and anti-cholinergic activity. The active compounds of CAE were docked with AChE and BuChE in molecular docking study.

RESULTS

The results showed that CAE treatment improves behavioral performance; attenuates the age-associated increase in MDA content, SOD, and AChE activity; and reduces neuronal loss. In vitro study showed that CAE has concentration-dependent antioxidant and anti-AChE activity. Furthermore, the presence of Asiatic acid and Madecassic acid in CAE and their good binding with cholinergic enzymes (in silico) also suggest the anticholinergic effect of CAE.

CONCLUSION

The findings of the current study show that the anticholinergic and antioxidant effects of CAE are attributable to the presence of Asiatic acid and Madecassic acid, which not only provide neuroprotection against age-associated cognitive decline but also reverse it.

Perinatal exposure to bisphenol A or S: Effects on anxiety-related behaviors and serotonergic system

Bisphenols, synthetic organic compounds used in the production of plastics, are an extremely abundant class of Endocrine Disrupting Chemicals, i.e., exogenous chemicals or mixtures of chemicals that can interfere with any aspect of hormone action. Exposure to BPs can lead to a wide range of effects, and it is especially dangerous if it occurs during specific critical periods of life. Focusing on the perinatal exposure to BPA or its largely used substitute BPS, we investigated the effects on anxiety-related behaviors and the serotonergic system, which is highly involved in controlling these behaviors, in adult mice. We treated C57BL/6J dams orally with a dose of 4 μg/kg body weight/day (i.e., EFSA TDI) of BPA or BPS dissolved in corn oil or with vehicle alone, at the onset of mating and continued treatment until the offspring were weaned. Adult offspring of both sexes performed the elevated plus maze and the open field tests. Then, we analyzed the serotonergic system in dorsal (DR) and median (MnR) raphe nuclei by immunohistochemical techniques. Behavioral tests highlighted alterations in BPA- and BPS-treated mice, suggesting different effects of the bisphenols exposure on anxiety-related behavior in males (anxiolytic) and females (anxiogenic). The analysis of the serotonergic system highlighted a sex dimorphism in the DR only, with control females showing higher values of serotonin immunoreactivity (5-HT-ir) than control males. BPA-treated males displayed a significant increase of 5-HT-ir in all analyzed nuclei, whereas BPS-treated males showed an increase in ventral DR only. In females, both bisphenols-treated groups showed a significant increase of 5-HT-ir in dorsal DR compared to the controls, and BPA-treated females also showed a significant increase in MnR.These results provide evidence that exposure during the early phases of life to BPA or BPS alters anxiety and the raphe serotonergic neurons in a sex-dependent manner.

Neurodevelopment effects of early life bisphenol-A exposure on visual memory: Insights into recovery dynamics

Bisphenol A (BPA), a ubiquitous endocrine disruptor, is implicated in the cognitive deficits observed in both children and animals. Especially, BPA-induced spatial memory deterioration during the whole development phase of rodents has been well delineated. However, whether BPA exposure on the different development phases exerts similar effects on the prefrontal cortex (PFC) dependent visual memory is still elusive. Here, we chose two exposure windows, the whole gestation and lactation phases (E0∼P21) and the whole juvenile and adolescent phases (P22∼P60), for exposing rats to BPA. The visual memory of those rats was accessed by object recognition testing in the open field after BPA exposure and a constant recovery interval. The results revealed a substantial decline of visual memory under both exposure conditions, accompanied by an increase in anxiety-like behavior in BPA-exposed rats. Notably, after a 20-day recovery period, those behavioral changes induced by BPA exposure during P22∼60, not E0∼P21, were reversed compared to the control rats. According to morphological analysis of those rats after recovery, we found that the spine density of pyramidal neurons in the PFC were significant decreased in rats with BPA exposure during E0∼P21 and there was no difference between rats with or without BPA exposure during P22∼P60. Additionally, a similar change trend in excitatory receptors expression was observed under both exposure conditions. After an additional 20 days of recovery, the behavioral changes in rats with perinatal BPA exposure reverted to the normal status. Our present findings illuminate the dynamic effects of BPA on PFC-dependent functions across two crucial early developmental stages of life.

Prenatal exposure to bisphenol A and/or diethylhexyl phthalate alters stress responses in rat offspring in a sex- and dose-dependent manner

Background: Prenatal exposures to endocrine disrupting chemicals (EDCs) are correlated with adverse behavioral outcomes, but the effects of combinations of these chemicals are unclear. The aim of this study was to determine the dose-dependent effects of prenatal exposure to EDCs on male and female behavior. Methods: Pregnant Sprague-Dawley rats were orally dosed with vehicle, bisphenol A (BPA) (5 μg/kg body weight (BW)/day), low-dose (LD) diethylhexyl phthalate (DEHP) (5 μg/kg BW/day), high-dose (HD) DEHP (7.5 mg/kg BW/day), a combination of BPA and LD-DEHP (B + D (LD)), or a combination of BPA and HD-DEHP (B + D (HD)) on gestational days 6-21. Adult offspring were subjected to the Open Field Test (OFT), Elevated Plus Maze (EPM), and Shock Probe Defensive Burying test (SPDB) in adulthood. Body, adrenal gland, and pituitary gland weights were collected at sacrifice. Corticosterone (CORT) was measured in the serum. Results: Female EDC-exposed offspring showed anxiolytic effects in the OFT, while male offspring were unaffected. DEHP (HD) male offspring demonstrated a feminization of behavior in the EPM. Most EDC-exposed male offspring buried less in the SPDB, while their female counterparts showed reduced shock reactivity, indicating sex-specific maladaptive alterations in defensive behaviors. Additionally, DEHP (LD) males and females and B + D (LD) females displayed increased immobility in this test. DEHP (LD) alone and in combination with BPA led to lower adrenal gland weights, but only in male offspring. Finally, females treated with a mixture of B + D (HD) had elevated CORT levels. Conclusion: Prenatal exposure to BPA, DEHP, or a mixture of the two, affects behavior, CORT levels, and adrenal gland weights in a sex- and dose-dependent manner.

Study of the Sensing Kinetics of G Protein-Coupled Estrogen Receptor Sensors for Common Estrogens and Estrogen Analogs

Endogenous and exogenous estrogens are widely present in food and food packaging, and high levels of natural estrogens and the misuse or illegal use of synthetic estrogens can lead to endocrine disorders and even cancer in humans. Therefore, it is consequently important to accurately evaluate the presence of food-functional ingredients or toxins with estrogen-like effects. In this study, an electrochemical sensor based on G protein-coupled estrogen receptors (GPERs) was fabricated by self-assembly, modified by double-layered gold nanoparticles, and used to measure the sensing kinetics for five GPER ligands. The interconnected allosteric constants (K_a) of the sensor for 17β-estradiol, resveratrol, G-1, G-15, and bisphenol A were 8.90 × 10^-17, 8.35 × 10^-16, 8.00 × 10^-15, 5.01 × 10^-15, and 6.65 × 10^-16 mol/L, respectively. The sensitivity of the sensor for the five ligands followed the order of 17β-estradiol > bisphenol A > resveratrol > G-15 > G-1. The receptor sensor also demonstrated higher sensor sensitivity for natural estrogens than exogenous estrogens. The results of molecular simulation docking showed that the residues Arg, Glu, His, and Asn of GPER mainly formed hydrogen bonds with -OH, C-O-C, or -NH-. In this study, simulating the intracellular receptor signaling cascade with an electrochemical signal amplification system enabled us to directly measure GPER-ligand interactions and explore the kinetics after the self-assembly of GPERs on a biosensor. This study also provides a novel platform for the accurate functional evaluation of food-functional components and toxins.

The passive avoidance task ameliorate the toxic effects of bisphenol A on dopamine D1 receptor density in hippocampus, amygdala, and cerebellum of male rats

INTRODUCTION

Dopamine D1 receptor seems to play a role in mediating plasticity. Therefore, the present study aimed to investigate the effects of passive avoidance tasks postexposed to BPA on dopamine D1 receptor density in the hippocampus, amygdala, and cerebellum of male rats.

METHODS

Thirty-five male Sprague-Dawley rats weighing 220.300 g, in standard light-dark 12 h light/12 h dark were used in the present study; water and food were ad libitum. Animals were divided into six groups. Administration of BPA 5 and 50 mg/kg/day were gavaged for 15 days. Learning and memory assessment were done by a shuttle box after 15 days of BPA administration. The density of the dopamine D1 receptor was investigated using an immunohistochemistry (IH) procedure. For determining the color difference in IH sections, Image Analyzer software was used. The data were analyzed by one-way ANOVA followed by Tukey's as a post hoc test.

RESULTS

The data showed that BPA in both doses could significantly increase the density of dopamine D1 receptors in the hippocampus, amygdala, and cerebellum of male rats; learning in rats postexposed to BPA improves dopamine D1 receptor density significantly in three brain structures.

DISCUSSION

According to the results, passive avoidance learning and memory can improve the density of dopamine D1 receptors in the hippocampus, amygdala, and cerebellum of male rats.

A human-relevant mixture of endocrine disrupting chemicals induces changes in hippocampal DNA methylation correlating with hyperactive behavior in male mice

Humans are ubiquitously exposed to endocrine disrupting chemicals (EDCs), substances that interfere with endogenous hormonal signaling. Exposure during early development is of particular concern due to the programming role of hormones during this period. A previous epidemiological study has shown association between prenatal co-exposure to 8 EDCs (Mixture N1) and language delay in children, suggesting an effect of this mixture on neurodevelopment. Furthermore, in utero exposure to Mixture N1 altered gene expression and behavior in adult mice. In this study, we investigated whether epigenetic mechanisms could underlie the long term effects of Mixture N1 on gene expression and behavior. To this end, we analyzed DNA methylation at regulatory regions of genes whose expression was affected by Mixture N1 in the hippocampus of in utero exposed mice using bisulfite-pyrosequencing. We show that Mixture N1 decreases DNA methylation in males at three genes that are part of the hypothalamus-pituitary-adrenal (HPA) axis: Nr3c1, Nr3c2, and Crhr1, coding for the glucocorticoid receptor, the mineralocorticoid receptor, and the corticotropin releasing hormone receptor 1, respectively. Furthermore, we show that the decrease in Nr3c1 methylation correlates with increased gene expression, and that Nr3c1, Nr3c2, and Crhr1 methylation correlates with hyperactivity and reduction in social behavior. These findings indicate that an EDC mixture corresponding to a human exposure scenario induces epigenetic changes, and thus programming effects, on the HPA axis that are reflected in the behavioral phenotypes of the adult male offspring.

Piracetam as a Therapeutic Agent for Doxorubicin-Induced Cognitive Deficits by Enhancing Cholinergic Functions and Reducing Neuronal Inflammation, Apoptosis, and Oxidative Stress in Rats

Cancer chemotherapy is known to cause cognitive defects in patients. Our study investigated the effect of piracetam (PIRA; 200 or 400 mg/kg) against doxorubicin (DOX)-induced cognitive deficits in a rat model. The cognitive parameters were analyzed using elevated plus-maze, novel object recognition, and Y-maze tests. Acetylcholinesterase (AChE), neuroinflammatory mediators (cyclooxygenase-2 (COX-2), prostaglandin E2 (PGE2), nuclear factor-κB (NF-κB), tumor necrosis factor-alpha (TNF-α)), apoptotic proteins (B-cell lymphoma-2 (Bcl-2), Bcl2 associated X protein (Bax), cysteine aspartate specific protease-3 (caspase-3)), oxidative parameters (malondialdehyde (MDA), catalase (CAT), and glutathione (GSH)) were also determined in the brain. PIRA administration offered significant protection against DOX-induced cognitive deficits in all maze tests and restored cholinergic functions via a significant reduction in AChE levels. Additionally, PIRA suppressed DOX-induced neuroinflammatory mediators (COX-2, PGE2, NF-κB, and TNF-α), pro-apoptotic proteins (Bax and caspase-3), and oxidative stress (MDA). Besides, it facilitated antioxidant (CAT and GSH) levels. Hence, our study highlighted that the neuroprotective activity of PIRA against DOX-induced cognitive deficits can be linked to reductions of AChE levels, neuro-inflammatory mediators, pro-apoptotic proteins, and oxidative stress.

Centella asiatica Alleviates AlCl3-induced Cognitive Impairment, Oxidative Stress, and Neurodegeneration by Modulating Cholinergic Activity and Oxidative Burden in Rat Brain

Aluminum (Al) is linked to the development of many neurological disorders such as Alzheimer's disease (AD), Parkinson's disease, and autism. Centella asiatica (CA) is a regenerating herb traditionally used to stimulate memory. This study was designed to assess the neuroprotective role of ethanolic extract of CA (CAE) in AlCl₃-induced neurological conditions in rats. Adult rats were chronically treated with AlCl₃ (100 mg/kg b.w./day) for 60 days to establish the dementia model, and co-administration of CAE was evaluated for its ability to attenuate the toxic effect of AlCl₃. CAE was given orally at a dose of 150 and 300 mg/kg b.w./day, for 60 days. The behavioral performances of rats were tested through Y-maze and open field tests. Lipid peroxidation, superoxide dismutase, and catalase activity were evaluated to measure oxidative stress; and acetylcholinesterase (AChE) activity was assessed to evaluate cholinergic dysfunction in the rat brain. H&E staining was used to assess structural abnormalities in the cortex and hippocampus. The result showed that AlCl₃ induces cognitive dysfunction (impaired learning and memory, anxiety, diminished locomotor activity), oxidative stress, cholinergic impairment, and histopathological alteration in the rat brain. Co-administration of CAE with AlCl₃ markedly protects the brain from AlCl₃-induced cognitive dysfunction, oxidative stress, AChE activity, and cytoarchitectural alterations. Furthermore, 15 days CAE treatment after 45 days AlCl₃ administration markedly ameliorates the AlCl₃-induced neurotoxicity indicating its potential for therapeutic use.

Prenatal bisphenol A exposure in relation to behavioral outcomes in girls aged 4-5 and modification by socio-demographic factors in The Infant Development and Environment Study (TIDES)

Bisphenol A (BPA) is a polymer used in the production of polycarbonate plastics and epoxy resins. An estrogen mimic, prenatal BPA exposure has been associated with several behavioral outcomes in children; however, the impact of maternal demographic and economic factors on associations between BPA and child behavioral outcomes have not been examined. The objective of this study was to examine associations between prenatal maternal urinary BPA and behavior in 4-5 year old girls, and to assess whether socio-demographic factors modify this relationship. Mothers enrolled in The Infant Development and Environment Study (TIDES) provided a single spot urine at enrollment (median gestational age 11 weeks) and completed the Behavior Assessment System for Children-2 (BASC-2) and Social Responsiveness Scale-2 (SRS-2) when their daughters were 4-5 years of age. Mother-daughter pairs with complete phthalate, BASC-2, SRS-2, and covariate data were included in this analysis (N = 244). BPA was detectable in 93 % of urine samples. We used multivariable linear regression analyses to estimate associations between maternal urinary log₁₀-transformed BPA concentration and BASC-2 subscale and composite scores and SRS-2 Total Score. To examine the role of socioeconomic and demographic factors associated with study site, we stratified by TIDES center, comparing those enrolled at University of Rochester Medical Center (URMC), a predominately lower socioeconomic population, and those enrolled elsewhere: University of Washington, University of Minnesota, and University of California San Francisco, whose populations share similar higher socioeconomic demographic characteristics. Across all centers, no associations were seen between BPA and BASC-2 or SRS-2 scores. When stratifying by center, BPA was significantly associated with greater social impairment as measured by the SRS-2 Total Score (β-coefficient [95 % confidence intervals]: 5.1 [1.0, 9.2]) in URMC participants (N = 61). In non-URMC participants (N = 183), BPA was significantly associated with lower BASC-2 Internalizing composite (-3.3 [-6.7, 0.0]) and Depression subscale scores (-3.4 [-6.7, 0.0]) while no associations were seen between BPA and SRS-2 scores. Our findings suggest that sociodemographic factors may modify the impacts of maternal prenatal BPA on developmental endpoints.

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.

Sukkari dates seed improves type-2 diabetes mellitus-induced memory impairment by reducing blood glucose levels and enhancing brain cholinergic transmission: In vivo and molecular modeling studies

Cognitive decline is one of the serious complications associated with diabetes mellitus (T2DM) of type-2. In this reported work, the effect of aqueous sukkari dates seed extract (ASSE) was evaluated in T2DM-induced rats. T2DM was induced using intraperitoneal injection of nicotinamide and streptozocin (STZ) administration. The diabetic rats were then treated orally with 200 mg/kg and 400 mg/kg of dates seed extract for 30 days and results were compared with metformin-treated groups. The memory functions were assessed using three maze models. Glucose and insulin levels in the blood and acetylcholine, acetylcholinesterase brain homogenates were estimated. The results showed a significant reduction in transfer latency (TL) (p < 0.001) during the elevated plus maze (EPM) test. The novel object recognition (NOR) test revealed a longer exploration time (p > 0.05) with novel objects and a higher discrimination index (p > 0.05). The Y-maze test also showed a significant increase in the number of entries to the novel arm (p > 0.05) and the total number of entries in the trial (p > 0.01) as well as in test (p > 0.05) sessions. Reduction in blood glucose (p > 0.05) and improvement in blood insulin (p > 0.05) levels were also noted. Improvement in ACh levels (p > 0.001) with 400 mg/kg of ASSE and reduction in AChE (p > 0.001) with both doses of ASSE were also observed in the brain homogenates. The results of ASSE were found comparable with the metformin-treated rats. The estimation of phytochemical constituents displayed a significant presence of phenolic content. Further, molecular modeling studies showed ellagic acid, catechin, and epicatechin as the potential molecule interacting with GSK-3β, α-amylase, and AChE and may be responsible for observed bioactivity. In conclusion, ASSE has the ability to alleviate T2DM-related cognitive impairments.

Aqueous Ajwa dates seeds extract improves memory impairment in type-2 diabetes mellitus rats by reducing blood glucose levels and enhancing brain cholinergic transmission

Diabetes is a metabolic disorder prevalent across the globe and is known to cause brain dysfunction, especially memory and cognitive decline. The current study investigates the effect of aqueous Ajwa seeds extract (AASE) on type-2 diabetes mellitus (T2DM)-induced memory deficits using a rat model. T2DM was induced by an administration of nicotinamide (120 mg/kg, i.p.) and streptozotocin (STZ) (60 mg/kg, i.p.). AASE (200 and 400 mg/kg, p.o.) were treated to T2DM rats for 30 days and the results were compared with the metformin (200 mg/kg). Elevated plus maze (EPM), Y-maze, and novel object recognition (NOR) tests were performed to assess the memory functions. The blood glucose and plasma insulin levels were estimated to assess the anti-diabetic effects of AASE. Acetylcholine (ACh) and acetylcholinesterase (AChE) levels were estimated from brain homogenates to assess cholinergic transmission. Treatment with AASE resulted in the reversal of behavioral deficits. EPM showed, a significant reduction in transfer latency (TL) among T2DM rats. High exploration time with a novel object and improvement in discrimination index were observed among treated groups during the NOR test. The Y-Maze test improved the entries and also time spent in the novel arm. Moreover, treatment of AASE reversed hyperglycemic and enhanced plasma insulin levels (200 mg/kg: 3.81 ± 0.08 ng/ml and 400 mg/kg: 4.09 ± 0.10 ng/ml) among T2DM rats (2.81 ± 0.15 ng/ml). Improved ACh levels (200 mg/kg: 186.6 ± 9.51 pg/mg protein and 400 mg/kg: 165.5 ± 9.25 pg/mg protein) and reduced AChE levels (200 mg/kg: 0.29 ± 0.02 ng/mg protein and 400 mg/kg: 0.32 ± 0.03 ng/mg protein) were also noted in the brain of AASE treated groups as referred to diabetic group (ACh: 107.1 ± 7.16 pg/mg protein and AChE: 0.51 ± 0.03 ng/mg protein). The above results were found to be comparable with the metformin-treated groups. From the results, it can be concluded that AASE has the potential to improve T2DM associated cognitive deficits.

Bisphenol A impairs cognitive function and 5-HT metabolism in adult male mice by modulating the microbiota-gut-brain axis

Bisphenol A (BPA) has been found to promote hepatotoxicity, reproductive toxicity, and developmental toxicity. However, the neurotoxicity and mechanism of BPA on cognitive function are still unclear. To that end, eight-week-old adult male and female C57BL/6J mice were exposed to 0.05, 0.5, 5, and 50 mg/kg BPA by dietary supplementation for 22 weeks. BPA exposure impaired learning and memory in male mice, associated with increased neuroinflammation and damaged blood-brain barrier. BPA exposure reduced the tight junctions in the colon, resulting in dysfunction of the gut barrier. The levels of neurotransmitters in the serum, hippocampus, and colon of male mice, including tryptophan, 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid, were all decreased by BPA, together with reduced expression of tryptophan and 5-HT metabolism-related genes. Cecal microbiota analysis revealed that the diversity and composition of the microbiota in male mice were markedly altered by BPA, leading to functional profile changes in the microbial community. These results suggest that the neurotoxicity of BPA in male mice may be partly regulated by the interactions of the microbiota-gut-brain axis. However, BPA has little effect on the cognitive function in female mice, which might be caused by the microbial differences and the role of estrogen receptors.

Endocrine-disrupting chemicals and behaviour: A high risk to take?

Early life exposure to endocrine-disrupting chemicals (EDCs) is considered a potential risk factor for aberrant brain development and the emergence of behavioral deficits. The purpose of this review is to summarize the toxic effects of bisphenol-A (BPA) and phthalate exposure during pre-, -post- or perinatal life on different types of behaviour in male and female rodents. Despite results not being always consistent, most probably due to methodological issues, it is highly probable that early life exposure to BPA or/and phthalates, affects various aspects of behaviour in the offspring. Adverse effects include: Increased levels of anxiety, altered exploratory behaviour, reduced social interaction or increased aggression and deficits in spatial or recognition learning and memory. These effects have been observed with a wide range of doses, in some cases even below the currently employed Tolerable Daily Intake dose for either BPA or phthalates.

Low concentration Tetrabromobisphenol A (TBBPA) elevating overall metabolism by inducing activation of the Ras signaling pathway

Tetrabromobisphenol A (TBBPA), one of the most common flame retardants, affects neurodevelopment, disrupts the endocrine system, and increases the possibility of tumorigenesis. This study investigates the cytotoxic effects, genetic effects, and metabolic effects from exposure to low concentration TBBPA. The cell exposure was measured by mimicking the residual TBBPA concentrations in human plasma, specifically in occupational populations. Our results revealed that long-term TBBPA exposure, especially at 1 nM concentration, significantly promoted the proliferation of HepG2 cells. Furthermore, long-term TBBPA exposure can double the levels of reactive oxygen species (ROS) released from mitochondria, thereby increasing Adenosine Monophosphate activated Protein kinase (AMPK) gene expression level to promote cellular proliferation. However, ROS can also mediate the apoptosis process through the mitochondrial membrane potential (MMP). The RNA-seq analysis confirmed that the Ras signaling pathway was activated by the growth factor to mediate cell detoxification mechanism, increasing lipid and vitamin metabolic rate. Our work uncovers a cellular mechanism by which long-term exposure to low concentration TBBPA can induce the activation of the Ras signaling pathway and demonstrates potential metabolic disorder in the human hepatic cells upon plasma TBBPA exposure.

Neuroendocrine disruption by bisphenol A and/or di(2-ethylhexyl) phthalate after prenatal, early postnatal and lactational exposure

Bisphenol A (BPA) and di(2-ethylhexyl)phthalate (DEHP) are abundant endocrine disrupting chemicals (EDCs). In recent years, studies showed that EDCs may lead to neurodevelopmental diseases. The effects of prenatal exposure to these chemicals may have serious consequences. Moreover, exposure to EDCs as a mixture may have different effects than individual exposures. The present study aimed to determine the toxicity of BPA and/or DEHP on central nervous system (CNS) and neuroendocrine system in prenatal and lactational period in Sprague-Dawley rats. Pregnant rats were randomly divided into four groups: control (received vehicle); BPA group (received BPA at 50 mg/kg/day); DEHP group (received DEHP at 30 mg/kg/day); and combined exposure group (received both BPA at 50 mg/kg/day and DEHP at 30 mg/kg/day) during pregnancy and lactation by oral gavage. At the end of lactation, male offspring (n = 6) were randomly grouped. The alterations in the brain histopathology, neurotransmitter levels and enzyme activities in the cerebrum region, oxidative stress markers, and apoptotic effects in the hippocampus region were determined at adulthood. The results showed that exposure to EDCs at early stages of life caused significant changes in lipid peroxidation, total GSH and neurotransmitter levels, and activities of neurotransmitter-related enzymes. Moreover, BPA and/or DEHP led to apoptosis and histopathologic alterations in the hippocampus. Therefore, we can suggest that changes in oxidant/antioxidant status, as well as in neurotransmitters and related enzymes, can be considered as the underlying neurotoxicity mechanisms of BPA and DEHP. However, more mechanistic studies are needed.

Adult Male Rats Show Resilience to Adolescent Bisphenol A Effects on Hormonal and Behavioral Responses While Co-Exposure With Hop Extracts Supports Synergistic Actions

The adolescence period, marked by sexual and brain maturation, has shown sensitivity to various environmental disruptors. Exposure to the xenoestrogen bisphenol A (BPA) is known to alter physiological and behavioral responses although its role at this critical period remains largely unknown. Recent research further suggests biochemical and genomic effects of BPA to be mitigated by various natural compounds, while effects on behavior have not been examined. This study aimed to characterize (1) the effects of dietary BPA during adolescence on endogenous corticosterone (CORT) secretion, emotional behavior, and testosterone (T) in adulthood, and (2) the impact of combined exposure to BPA with hop extracts (Hop), a phytoestrogen with anxiolytic properties. To do so, four groups of male Wistar rats [postnatal day (PND) 28] were administered corn oil (control), BPA (40 mg/kg), hops (40 mg/kg), or BPA-hops by oral gavage for 21 days (PND 28–48). Blood droplets collected on PND 28, 48, and 71 served to measure CORT and T changes. As adults, rats were tested in the elevated plus maze (EPM), the social interaction test, and the forced swim test. Our findings demonstrated elevated anxiety and a trend toward depressive-like behaviors in BPA- compared to hops-exposed rats. However, BPA intake had no impact on basal CORT levels, or adulthood T secretion and sociability. Of note, BPA's anxiogenic effect manifested through decreased EPM open arm entries was abolished by hops co-supplementation. Together, our observations suggest the adolescence period to be less sensitive to deleterious effects of BPA than what has been reported upon gestational and perinatal exposure.

The impact of endocrine-disrupting chemical exposure in the mammalian hypothalamic-pituitary axis

The hypothalamic-pituitary axis (HP axis) plays a critical and integrative role in the endocrine system control to maintain homeostasis. The HP axis is responsible for the hormonal events necessary to regulate the thyroid, adrenal glands, gonads, somatic growth, among other functions. Endocrine-disrupting chemicals (EDCs) are a worldwide public health concern. There is growing evidence that exposure to EDCs such as bisphenol A (BPA), some phthalates, polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and biphenyls (PBBs), dichlorodiphenyltrichloroethane (DDT), tributyltin (TBT), and atrazine (ATR), is associated with HP axis abnormalities. EDCs act on hormone receptors and their downstream signaling pathways and can interfere with hormone synthesis, metabolism, and actions. Because the HP axis function is particularly sensitive to endogenous hormonal changes, disruptions by EDCs can alter HP axis proper function, leading to important endocrine irregularities. Here, we review the evidence that EDCs could directly affect the mammalian HP axis function.

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.

4-tert-Octylphenol Exposure Disrupts Brain Development and Subsequent Motor, Cognition, Social, and Behavioral Functions

The endocrine-disrupting chemical 4-tert-octylphenol (OP) is a widespread estrogenic chemical used in consumer products such as epoxy resins and polycarbonate plastic. However, the effects of OP on brain development are unknown. The present study examined the effects of OP on neuron and neurobehavioral development in mice. By using primary cortical neuron cultures, we found that OP-treated showed a decreased length of axons and dendrites and an increased number of primary and secondary dendrites. OP reduced bromodeoxyuridine (BrdU), mitotic marker Ki67, and phospho-histone H3 (p-Histone-H3), resulting in a reduction of neuronal progenitor proliferation in offspring mouse brain. Moreover, OP induced apoptosis in neuronal progenitor cells in offspring mouse brain. Furthermore, offspring mice from OP-treated dams showed abnormal cognitive, social, and anxiety-like behaviors. Taken together, these results suggest that perinatal exposure to OP disrupts brain development and behavior in mice.

Phthalate and Bisphenol Exposure during Pregnancy and Offspring Nonverbal IQ

BACKGROUND

Prenatal exposures to phthalates and bisphenols are associated with impaired brain development in animals. However, epidemiological studies investigating the association between prenatal phthalate or bisphenol exposure and cognition have produced mixed findings and mostly had modest sample sizes and measured the exposure during the third trimester.

OBJECTIVE

We examined the association between pregnancy maternal urinary biomarkers of phthalate or bisphenol exposure and nonverbal intelligence quotient (IQ) in children 6 years of age.

METHOD

The study sample consisted of 1,282 mother-child pairs participating in the Generation R Study, a population-based birth cohort in Rotterdam, Netherlands (enrollment 2002-2006). We measured maternal urinary concentrations of 18 phthalate metabolites and 8 bisphenols at < 18 , 18-25, and > 25  wks of gestation. Child nonverbal IQ was measured at 6 years of age using the Snijders-Oomen Nonverbal Intelligence Test-Revised. Linear regression models were fit for each of the three collection phases separately, the three collection phases jointly, and for the averaged prenatal exposure across pregnancy.

RESULTS

Higher urinary concentrations of phthalate metabolites during early pregnancy were associated with lower child nonverbal IQ score [e.g., B per 10-fold increase in summed low-molecular weight phthalates = - 1.7 (95% CI: - 3.1 , - 0.3 )]. This association remained unchanged when adjusted for mid and late pregnancy exposures. We also observed an inverse association between late pregnancy di-n-octyl phthalate (DNOP) exposure and nonverbal IQ. Maternal urinary concentrations of bisphenols were not associated with child nonverbal IQ. There was no effect estimate modification by sex.

CONCLUSIONS

We did not observe that maternal biomarkers of bisphenol exposure are associated with nonverbal IQ. We found that phthalate exposure in early pregnancy and DNOP exposure in late pregnancy are associated with lower nonverbal IQ scores in children. Our results might suggest that particularly early pregnancy is a sensitive window of phthalate exposure, but future studies are needed to replicate our findings. https://doi.org/10.1289/EHP6047.

Long term transcriptional and behavioral effects in mice developmentally exposed to a mixture of endocrine disruptors associated with delayed human neurodevelopment

Accumulating evidence suggests that gestational exposure to endocrine disrupting chemicals (EDCs) may interfere with normal brain development and predispose for later dysfunctions. The current study focuses on the exposure impact of mixtures of EDCs that better mimics the real-life situation. We herein describe a mixture of phthalates, pesticides and bisphenol A (mixture N1) detected in pregnant women of the SELMA cohort and associated with language delay in their children. To study the long-term impact of developmental exposure to N1 on brain physiology and behavior we administered this mixture to mice throughout gestation at doses 0×, 0.5×, 10×, 100× and 500× the geometric mean of SELMA mothers' concentrations, and examined their offspring in adulthood. Mixture N1 exposure increased active coping during swimming stress in both sexes, increased locomotion and reduced social interaction in male progeny. The expression of corticosterone receptors, their regulator Fkbp5, corticotropin releasing hormone and its receptor, oxytocin and its receptor, estrogen receptor beta, serotonin receptors (Htr1a, Htr2a) and glutamate receptor subunit Grin2b, were modified in the limbic system of adult animals, in a region-specific, sexually-dimorphic and experience-dependent manner. Principal component analysis revealed gene clusters associated with the observed behavioral responses, mostly related to the stress axis. This integration of epidemiology-based data with an experimental model increases the evidence that prenatal exposure to EDC mixtures impacts later life brain functions.

Perinatal exposure to bisphenol A at the intersection of stress, anxiety, and depression

Endocrine-disrupting compounds (EDCs) are common contaminants in our environment that interfere with typical endocrine function. EDCs can act on steroid and nuclear receptors or alter hormone production. One particular EDC of critical concern is bisphenol A (BPA) due to its potential harm during the perinatal period of development. Previous studies suggest that perinatal exposure to BPA alters several neurotransmitter systems and disrupts behaviors associated with depression and anxiety in the rodent offspring later in life. Thus, dysregulation in neurotransmission may translate to behavioral phenotypes observed in mood and arousal. Many of the systems disrupted by BPA also overlap with the stress system, although little evidence exists on the effects of perinatal BPA exposure in relation to stress and behavior. The purpose of this review is to explore studies involved in perinatal BPA exposure and the stress response at neurochemical and behavioral endpoints. Although more research is needed, we suggest that perinatal BPA exposure is likely inducing variations in behavioral phenotypes that modulate their action through dysregulation of neurotransmitter systems sensitive to stress and endocrine disruption.

Bisphenols as a Legacy Pollutant, and Their Effects on Organ Vulnerability

Bisphenols are widely used in the synthesis of polycarbonate plastics, epoxy resins, and thermal paper, which are used in manufacturing items of daily use. Packaged foods and drinks are the main sources of exposure to bisphenols. These chemicals affect humans and animals by disrupting the estrogen, androgen, progesterone, thyroid, and aryl hydrocarbon receptor functions. Bisphenols exert numerous harmful effects because of their interaction with receptors, reactive oxygen species (ROS) formation, lipid peroxidation, mitochondrial dysfunction, and cell signal alterations. Both cohort and case-control studies have determined an association between bisphenol exposure and increased risk of cardiovascular diseases, neurological disorders, reproductive abnormalities, obesity, and diabetes. Prenatal exposure to bisphenols results in developmental disorders in animals. These chemicals also affect the immune cells and play a significant role in initiating the inflammatory response. Exposure to bisphenols exhibit age, gender, and dose-dependent effects. Even at low concentrations, bisphenols exert toxicity, and hence deserve a critical assessment of their uses. Since bisphenols have a global influence on human health, the need to discover the underlying pathways involved in all disease conditions is essential. Furthermore, it is important to promote the use of alternatives for bisphenols, thereby restricting their uses.

Low-dose bisphenol A exposure impairs learning and memory ability with alterations of neuromorphology and neurotransmitters in rats

To investigate the developmental neurotoxicity of environmental bisphenol A (BPA) exposure for infants and children, postnatal rats were used as the animal model and were divided into four groups. Then, they were treated with different concentrations of BPA (i.e., 0, 0.5, 50, or 5000 μg/kg·bw/day of BPA as the control, low-, medium- and high-exposed group) from postnatal days 7 to 21. Y-maze tests, Golgi-Cox assays and liquid chromatography-tandem mass spectrometry (LC/MS/MS) were performed to test the changes of learning and memory ability, hippocampal neuromorphology and neurotransmitter levels, respectively. The results showed that the BPA-exposed rats, especially the low- and high-exposed rats, needed more trials and longer times to qualify for the learned criterion than the control rats. Additionally, rats after low- or high-exposure to BPA exhibited decreased DG dendritic complexity and reduced CA1 and DG dendritic spine densities in the hippocampus. Low-dosage BPA treatment could significantly alter the neurotransmitter contents in the hippocampus. In male rats, the levels of glutamic acid (Glu) and acetylcholine increased, while the 5-hydroxytryptamine (5-HT) and γ-aminobutyric acid (GABA) levels decreased, which lead to an unbalanced Glu/GABA ratio. However, in female rats, only 5-HT levels decreased. In conclusion, postnatal exposure to BPA could sex- and dose-dependently disrupt dendritic development and neurotransmitter homeostasis in the rat hippocampus. The impaired spatial learning and memory ability of rats induced by low-dose BPA is associated with both disrupted dendritic development and neurotransmitter homeostasis in the hippocampus.

Glucocorticoid and mineralocorticoid receptors and corticosteroid homeostasis are potential targets for endocrine-disrupting chemicals

Endocrine-disrupting chemicals (EDCs) have received significant concern, since they ubiquitously exist in the environment and are able to induce adverse health effects on human and wildlife. Increasing evidence shows that the glucocorticoid receptor (GR) and the mineralocorticoid receptor (MR), members of the steroid receptor subfamily, are potential targets for EDCs. GR and MR mediate the actions of glucocorticoids and mineralocorticoids, respectively, which are two main classes of corticosteroids involved in many physiological processes. The effects of EDCs on the homeostasis of these two classes of corticosteroids have also gained more attention recently. This review summarized the effects of environmental GR/MR ligands on receptor activity, and disruption of corticosteroid homeostasis. More than 130 chemicals classified into 7 main categories were reviewed, including metals, metalloids, pesticides, bisphenol analogues, flame retardants, other industrial chemicals and pharmaceuticals. The mechanisms by which EDCs interfere with GR/MR activity are primarily involved in ligand-receptor binding, nuclear translocation of the receptor complex, DNA-receptor binding, and changes in the expression of endogenous GR/MR genes. Besides directly interfering with receptors, enzyme-catalyzed synthesis and prereceptor regulation pathways of corticosteroids are also important targets for EDCs. The collected evidence suggests that corticosteroids and their receptors should be considered as potential targets for safety assessment of EDCs. The recognition of relevant xenobiotics and their underlying mechanisms of action is still a challenge in this emerging field of research.

Prenatal maternal and childhood bisphenol a exposure and brain structure and behavior of young children

BACKGROUND

Bisphenol A (BPA) is commonly used in the manufacture of plastics and epoxy resins. In North America, over 90% of the population has detectable levels of urinary BPA. Human epidemiological studies have reported adverse behavioral outcomes with BPA exposure in children, however, corresponding effects on children's brain structure have not yet been investigated. The current study examined the association between prenatal maternal and childhood BPA exposure and white matter microstructure in children aged 2 to 5 years, and investigated whether brain structure mediated the association between BPA exposure and child behavior.

METHODS

Participants were 98 mother-child pairs who were recruited between January 2009 and December 2012. Total BPA concentrations in spot urine samples obtained from mothers in the second trimester of pregnancy and from children at 3-4 years of age were analyzed. Children participated in a diffusion magnetic resonance imaging (MRI) scan at age 2-5 years (3.7 ± 0.8 years). Associations between prenatal maternal and childhood BPA and children's fractional anisotropy and mean diffusivity of 10 isolated white matter tracts were investigated, controlling for urinary creatinine, child sex, and age at the time of MRI. Post-hoc analyses examined if alterations in white matter mediated the relationship of BPA and children's scores on the Child Behavior Checklist (CBCL).

RESULTS

Prenatal maternal urinary BPA was significantly associated with child mean diffusivity in the splenium and right inferior longitudinal fasciculus. Splenium diffusivity mediated the relationship between maternal prenatal BPA levels and children's internalizing behavior (indirect effect: β = 0.213, CI [0.0167, 0.564]). No significant associations were found between childhood BPA and white matter microstructure.

CONCLUSIONS

This study provides preliminary evidence for the neural correlates of BPA exposure in humans. Our findings suggest that prenatal maternal exposure to BPA may lead to alterations in white matter microstructure in preschool aged children, and that such alterations mediate the relationship between early life exposure to BPA and internalizing problems.

Melatonin attenuates bisphenol A-induced toxicity of the adrenal gland of Wistar rats

This study investigated the role of melatonin (MLT) on adrenal gland toxicity induced by bisphenol A (BPA). Adult male rats were divided into four groups of seven animals each: Group I (control) received oral 0.2 ml canola oil; group II received intra-peritoneal 10 mg/kg BW/day MLT; and group III received oral BPA (10 mg/kg BW/day). Group IV rats were treated with same dose of BPA as group III with a concomitant intra-peritoneal 10 mg/kg BW/day MLT. All treatments lasted for 14 days. BPA significantly increased (P < 0.05) adrenal index, circulating levels of corticosterone and adrenocorticotropic hormone (ACTH) in the rats. BPA caused marked vascular congestion, hyperplasia, cellular distortion, increased lipid peroxidation, decreased antioxidant enzymes, and decreased expression of αSmooth muscle actin as well as vimentin proteins. The concomitant treatment with MLT ameliorated these BPA-induced alterations. It is likely that melatonin attenuates BPA-induced alterations of the adrenal gland of rats through the antioxidant defense mechanism.

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.

Bisphenol A exposure remodels cognition of male rats attributable to excitatory alterations in the hippocampus and visual cortex

Bisphenol A, an environmental xenoestrogen, has been shown sex-specific adverse effects on cognitive function of rodents. However, the specific mechanisms underlying these outcomes remain elusive, limiting our understanding the differences in behavioral impairments due to BPA exposure between genders in humans. The present study chose the juvenile stage (with a stable estrogen level) as the exposure window to explore BPA effects on cognitive behaviors of male and female Sprague-Dawley (SD) rats and related mechanisms. Three dosages of BPA (0.04, 0.4 and 4 mg/kg/day) were chose to make BPA-exposed models. Especially, the mid-dose for rats was close to the current reference daily limit for human exposure given by the U.S. Environmental Protection Agency. Our results showed that male but not female juvenile rats had a marked decline in spatial memory after 0.4 mg/kg/day BPA exposure, which accompanied with downregulation of glutamate receptor (NR2) expression in their hippocampus and primary visual cortex (V1). In the high-dose BPA exposed groups (4 mg/kg/day), there was not only a deficit of spatial memory, but also an anxiety-like behavior of male rats. Additionally, those rats had a significant decline in spine density of pyramidal neurons and a decreased expression of glutamate receptor subtypes (NR2 and GluR1) in the hippocampus. Importantly, such impairments in the hippocampus of male rats were associated with a decrease of glutamate receptor (NR2) expression in the V1, which could perturb the visual information inputs. To some extent, altered ERβ expression within their hypothalamus could contribute to the anxiety-like behavior after high-dose BPA exposure. However, the low-dose BPA exposed juvenile rats didn't present any structural and behavioral changes in our present study. Those results suggests that BPA exerts dose dependent and gender-specific effects on the cognition of juvenile animals. Our findings shed light on mechanisms underlying BPA effects on the juvenile animals.

Atypical fetal development: Fetal alcohol syndrome, nutritional deprivation, teratogens, and risk for neurodevelopmental disorders and psychopathology

Accumulating evidence indicates that the fetal environment plays an important role in brain development and sets the brain on a trajectory across the life span. An abnormal fetal environment results when factors that should be present during a critical period of development are absent or when factors that should not be in the developing brain are present. While these factors may acutely disrupt brain function, the real cost to society resides in the long-term effects, which include important mental health issues. We review the effects of three factors, fetal alcohol exposure, teratogen exposure, and nutrient deficiencies, on the developing brain and the consequent risk for developmental psychopathology. Each is reviewed with respect to the evidence found in epidemiological and clinical studies in humans as well as preclinical molecular and cellular studies that explicate mechanisms of action.

Bisphenol-A inhibits improvement of testosterone in anxiety- and depression-like behaviors in gonadectomied male mice

Bisphenol-A (BPA) is a well-known environmental endocrine disruptor. Developmental exposure to BPA affected a variety of behaviors in multiple model organisms. Our recent study found that exposure to BPA during adulthood aggravated anxiety- and depression-like states in male mice but not in females. In this study, 11-w-old gonadectomied (GDX) male mice daily received subcutaneous injections of testosterone propionate (TP, 0.5 mg/kg), TP and BPA (0.04, 0.4, or 4 mg/kg), or vehicle for 45 days. BPA (0.4 or 4 mg/kg) did not affect the elevated plus maze task of GDX mice but shortened the time on open arms and decreased the frequency of head dips of sham and TP-GDX mice. In forced swim task, BPA prolonged the total time of immobility of both sham and TP-GDX mice but not GDX mice. In addition, BPA reduced the levels of T in the serum and the brain of sham and TP-GDX mice. Western blot analysis further showed that BPA reduced the levels of androgen receptor (AR) and GABA(A)α2 receptor of the hippocampus and the amygdala in sham and inhibited the rescue of TP in these proteins levels of GDX mice. Meanwhile, BPA decreased the level of phospho-ERK1/2 in these two brain regions of sham and TP-GDX mice. These results suggest that long-term exposure to BPA inhibited TP-improved anxiety- and depression-like behaviors in GDX male mice. The down-regulated levels of GABA(A)α2 receptor and AR and an inhibited activity of ERK1/2 pathway in the hippocampus and the amygdala may be involved in these process.

Repeated olanzapine treatment mitigates PTSD like symptoms in rats with changes in cell signaling factors

Post Traumatic Stress Disorder is an anxiety disorder with prolonged distortion of rational behavior. In this study, we report the preclinical potential of olanzapine (OLZ) in the treatment of PTSD. Since the atypical antipsychotics have modulating effects on cell protective and destructive factors, we tested the effects of OLZ in PTSD regarding these cell modulating factors. Rats, when subjected to stress-restress (SRS) model of PTSD, showed a derangement in cell protective factors like the decline in BDNF, ERK, and CREB. While the adversarial factors like caspase-3 were enhanced. Four weeks treatment with OLZ at doses of 1 and 10 mg/kg significantly mitigated the SRS-induced derangement related to PTSD. OLZ at doses of 1 and 10 mg/kg enhanced BDNF, ERK and CREB levels which were reduced by SRS in PTSD animals. Further, at the fore mentioned doses it also inhibited the elevation of caspase-3 a downstream apoptotic factor. Besides, OLZ also showed mitigation in behavioral alterations related to anxiety and memory brought about by PTSD. These effects of OLZ were comparable to that of paroxetine a clinically approved drug for PTSD in terms of biochemical and behavioral assessments indicating its anti-PTSD potential.

Sex differences, endogenous sex-hormone hormones, sex-hormone binding globulin, and exogenous disruptors in diabetes and related metabolic outcomes

In assessing clinical and pathophysiological development of type 2 diabetes (T2D), the critical role of the sex steroids axis is underappreciated, particularly concerning the sex-specific relationships with many relevant cardiometabolic outcomes. In this issue of the Journal of Diabetes, we provide a comprehensive overview of these significant associations of germline variants in the genes governing the sex steroid pathways, plasma levels of steroid hormones, and sex hormone-binding globulin (SHBG) with T2D risk that have been observed in many clinical and high-quality large prospective cohorts of men and women across ethnic populations. Together, this body of evidence indicates that sex steroids and SHBG should be routinely incorporated into clinical characterization of T2D patients, particularly in screening prediabetic patients, such as those with metabolic syndrome, using plasma levels of SHBG. Given that several germline mutations in the SHBG gene have also been directly related to both plasma concentrations of SHBG and clinical manifestation of T2D, targeting signals in the sex steroid axis, particularly SHBG, may have significant utility in the prediction and treatment of T2D. Further, many of the environmental endocrine disrupting chemicals may exert their potential adverse effects on cardiometabolic outcomes via either estrogenic or androgenic signaling pathways, highlighting the importance of using the sex steroids and SHBG as important biochemical markers in both clinical and population studies in studying sex-specific mechanisms in the pathogenesis of T2D and its complications, as well as the need to equitably allocate resources in studying both men and women.

Evaluation of Dose Dependent Maternal Exposure to Bisphenol A on Thyroid Functions in Newborns

Bisphenol A (BPA) is an endocrine-disrupting chemical compound that is mainly used in industrial products as packaging and plastics. It usually transmits to humans via oral route from food-contact material. BPA has demonstrated to be found in body fluids with a higher amount of fetal tissues due to bio-accumulation. Although it has been reported to affect the endocrine system, results on thyroid functions of newborns are conflicting. The aim of the present study is to demonstrate the effect of different levels of BPA in cord blood on the thyroid functions of newborns, according to gender. Methods: The study population included 88 newborns. The BPA levels, Thyroid stimulating hormone (TSH) and free thyroxine (fT4) levels of cord blood were measured. In addition, SPINA-GT (thyroid’ incretory capasity), TSH Index (TSHI), standardized TSHI (sTSHI) were calculated and demographic characteristics of participants were noted. Results: The mean of cord blood BPA was 4.934 ± 2.33 ng/mL. When evaluated according to quantiles of BPA, no association was found between BPA and thyroid hormone levels, as well as, SPINA-GT, TSHI, sTSHI in both genders. Conclusion: Although BPA has been shown to contaminate cord blood, no significant effect was detected on thyroid hormones, SPINA-GT, TSHI and sTSHI. Further investigations with larger study populations are warranted.

Effects of maternal or paternal bisphenol A exposure on offspring behavior

Bisphenol A (BPA) is an endocrine disrupting chemical used in the production of polycarbonate plastics and resins. Exposure to BPA during gestation has been proposed as a risk factor for the development of neurobehavioral disorders, such as autism spectrum disorder. To address the behavioral impact of developmental exposure to BPA, we tested offspring of mice exposed to a daily low dose of BPA during pregnancy. We also asked if preconception exposure of the sire affected behaviors in offspring. Sires that consumed BPA for 50days prior to mating weighed less than controls, but no effects on any reproductive measures were noted. Juvenile offspring exposed to BPA maternally, but not paternally, spent less time in the open arms of the elevated plus maze than controls, indicating increased anxiety-like behavior. However, neither parental exposure group differed significantly from controls in the social recognition task. We also assessed the behaviors of maternally exposed offspring in two novel tasks: ultrasonic vocalizations (USVs) in pups and operant reversal learning in adults. Maternal BPA exposure increased the duration and median frequency of USVs emitted by pups during maternal separation. In the reversal learning task, females responded more accurately and earned more rewards than males. Additionally, control females received more rewards than BPA females during the acquisition phase of the task. These are among the first studies conducted to ask if BPA exposure via the sire affects offspring behavior and the first study to report effects of gestational BPA exposure on pup USVs and adult operant responding.

Effects of Bisphenol-A on proliferation and expression of genes related to synthesis of polyamines, interferon tau and insulin-like growth factor 2 by ovine trophectoderm cells

This study evaluated the effects of bisphenol A (BPA) on proliferation of ovine trophectoderm (oTr1) cells, as well as expression of genes for transport of arginine and synthesis of polyamines. BPA reduced proliferation of oTr1 cells at concentrations of 1 × 10^-6, 1 × 10^-5, 1 × 10^-4 M compared to concentrations of 0, 1 × 10^-9, and 1 × 10^-8 M at 24 and 96 h of culture. Lower concentrations of BPA significantly increased expression of mRNAs for agmatinase (AGMAT), arginine decarboxylase (ADC), ornithine decarboxylase (ODC1) and solute carrier family 7 member 1 (SLC7A1). Similarly, synthesis of polyamines by oTr1 cells was greatest at lower concentrations of BPA and decreased as the dose of BPA increased. Expression of mRNAs for interferon tau (IFNT) and insulin-like growth factor 2 (IGF2) by oTr1 cells was greater than for controls at 1 × 10^-9 M BPA. Overall, the effects of BPA on proliferation and gene expression by oTr1 cells were highly dose-dependent.

Thyroid-disrupting chemicals and brain development: an update

This review covers recent findings on the main categories of thyroid hormone-disrupting chemicals and their effects on brain development. We draw mostly on epidemiological and experimental data published in the last decade. For each chemical class considered, we deal with not only the thyroid hormone-disrupting effects but also briefly mention the main mechanisms by which the same chemicals could modify estrogen and/or androgen signalling, thereby exacerbating adverse effects on endocrine-dependent developmental programmes. Further, we emphasize recent data showing how maternal thyroid hormone signalling during early pregnancy affects not only offspring IQ, but also neurodevelopmental disease risk. These recent findings add to established knowledge on the crucial importance of iodine and thyroid hormone for optimal brain development. We propose that prenatal exposure to mixtures of thyroid hormone-disrupting chemicals provides a plausible biological mechanism contributing to current increases in the incidence of neurodevelopmental disease and IQ loss.

Preconception paternal bisphenol A exposure induces sex-specific anxiety and depression behaviors in adult rats

Bisphenol A (BPA), an environmental endocrine-disrupting compound, has drawn a great attention for its adverse effect on behavioral development. Maternal exposure to this compound has been reported to induce anxiety and depression in offspring, but the effect of its paternal exposure is rarely discussed. This study investigated whether preconception paternal BPA exposure can affect the emotions of male rats and their offspring. Eighteen adult male rats (F0) received either a vehicle or 50 μg/kg/day BPA diet for 21 weeks and were then mated with non-exposed females to produce offspring (F1). The affective behaviors of F0 and F1 rats were evaluated in the open-field test, the elevated-plus maze and the forced swimming test, and their serum corticosterone were then examined. BPA exposure induced increased anxiety behaviors along with increased serum corticosterone in F0 rats. This paternal exposure also led to increased anxiety behaviors in F1 females and aggravated depression behaviors in both sexes of F1 rats. Furthermore, only F1 females exhibited increased serum corticosterone. Overall, these data indicate that preconception paternal exposure to a low dose of BPA may induce transgenerational sex-specific impairments in the affection of adult rats.