Sex-specific Effects of Endocrine-disrupting Chemicals on Brain Monoamines and Cognitive Behavior

The Effect of Endocrine Disruptors on the Cardiovascular System: does sex matter?

Endocrine disruptors (EDs) are environmental chemicals that interfere with hormone function, posing significant risks to human health, including the cardiovascular system. This review comprehensively examines the impact of EDs on cardiovascular health, with a specific focus on sex differences observed in various models. Utilizing in-vitro studies, in vivo animal models, and human clinical data, we delineate how sex-specific hormonal environments influence the cardiovascular effects of ED exposure. In vitro studies highlight cellular and molecular mechanisms that differ between male and female-derived cells. In vivo models reveal distinct physiological responses and susceptibilities to EDs, influenced by sex hormones. Human studies provide epidemiological evidence and clinical observations that underscore the variability in cardiovascular outcomes between men and women. This review underscores the necessity of considering sex as a critical factor in understanding the cardiovascular implications of ED exposure, advocating for gender-specific risk assessment and therapeutic strategies. The findings aim to enhance awareness and inform future research and policy-making to mitigate the adverse cardiovascular effects of EDs across different sexes.

Mancozeb exposure disrupts endocrine function of the ovary and thyroid in Red Munia (Amandava amandava)

Mancozeb (MCZ), a dithiocarbamate fungicide, has the potential to disrupt thyroid hormone (TH) functioning in non-target organisms. THs play a crucial role in seasonal reproduction and previous studies have shown that even low levels of MCZ exposure can affect thyroid and testicular function in the Red Munia bird (Amandava amandava), a distinct seasonal breeder. This study specifically examines the impact of MCZ exposure on female Red Munia to investigate any sex-specific effects. Exposure to sublethal levels (0.5% LD50) of MCZ for 30 consecutive days during the critical transition to the breeding phase disrupts the pituitary-ovarian and pituitary-thyroid axes in Red Munia. The morphometry (number/size/immunointensity) of pituitary luteinizing hormone (LH) and thyroid-stimulating hormone (TSH) producing cells, immunoreacted with anti-human (h) LHβ/anti-chicken (c) LHβ, and anti-hTSH β respectively, was significantly altered. Plasma levels of LH (p < 0.01), follicle-stimulating hormone (p < 0.001), and TSH (p < 0.01) were significantly decreased. There was a significant increase in the number of atretic primordial and primary follicles, thinning and disorganization of the granulosa cell layers in maturing follicles, and significant decrease in plasma levels of estradiol (p < 0.001).The reduced diameter of the thyroid gland, a significant increase in empty follicles, and a decrease in plasma levels of THs (T3, p < 0.01; T4, p < 0.001), indicate disruption of thyroid function. It is not only MCZ and its residual products, but also the inert ingredients in the commercial formulation/metabolites, may have contributed to the interference with thyroid function during the transition to the breeding phase to compromise ovarian recrudescence in the Red Munia bird.

Association of Stmn1 Polymorphism and Cognitive Function: An Observational Study in the Chinese Adults

Background

Stathmin1 (Stmn1) is a protein highly expressed during the development of the central nervous system. The phosphorylation of Stmn1 involves microtubule dynamics, so Stmn1 plays a vital part in neurite outgrowth and synaptic plasticity. Previous studies reported that Stmn1 genetic variants influence fear and anxiety as well as cognitive-affective processing. However, no study reported on the relationship between Stmn1 gene polymorphism and cognition in Chinese. Thus, this association was investigated in the present study.

Methods

A total of 129 healthy Han Chinese were genotyped for Stmn1 rs182455 polymorphism by polymerase chain reaction and restriction fragment length polymorphism analyses. Cognitive function was assessed using the Stroop Color-Word Test (SCWT) and Hopkins Verbal Learning Test-Revised (HVLT-R).

Results

In the present sample, rs182455 CC, CT, and TT genotypes were found in 56 (43.41%), 65 (50.39%) and 8 (6.20%) cases, respectively. The genotype distribution did not deviate from Hardy-Weinberg equilibrium (χ2 = 3.715, p = 0.054). Significant differences were found between the three rs182455 genotypes and between the CC and (CT+TT) genotype groups in the Stroop Color (SC) scores of the SCWT (F = 3.322, 2.377; p = 0.039, 0.019, respectively) and the total recall (TR) scores on the HVLT-R (F = 3.118, 2.225; p = 0.048, 0.028, respectively). There was a female-specific difference in SC scores between the three rs182455 genotypes (F = 2.318, p = 0.023). The rs182455 genotype distribution showed no significant difference between two sexes (χ2 = 1.313, p = 0.519), whereas significant differences were seen in SC and TR scores between two sexes (t = -2.294, -2.490; p = 0.023, 0.014, respectively).

Conclusions

The findings suggest that rs182455 Stmn1 polymorphism might affect cognitive flexibility and immediate free recall in healthy Chinese individuals, especially females.

Two Hits of EDCs Three Generations Apart: Evaluating Multigenerational Anxiety-Like Behavioral Phenotypes in Female Rats Exposed to Aroclor 1221 and Vinclozolin

BACKGROUND

Endocrine-disrupting chemicals (EDCs) are exogenous chemical compounds that interfere with the normal function of the endocrine system and are linked to direct and inherited adverse effects in both humans and wildlife. Legacy EDCs such as polychlorinated biphenyls (PCBs) are no longer used yet remain detectable in biological specimens around the world; concurrently, we are exposed to newer EDCs like the fungicide vinclozolin (VIN). This combination of individuals' direct environmental chemical exposures and any heritable changes caused by their ancestors' chemical exposures leads to a layered pattern of both direct and ancestrally inherited exposures that might have cumulative effects over generations.

OBJECTIVES

We assessed consequences of both direct and ancestral exposure to EDCs over six generations, examining anxiety-like behaviors in maternal and paternal lines of female rats. We used the "two hits, three generations apart" multigenerational exposure model to explore how two distinct EDCs-the weakly estrogenic PCB mixture Aroclor 1221 (A1221) and the antiandrogenic VIN-interact on behavior across generations. We also explored serum hormones as a potential mechanism.

METHODS

Rats were prenatally exposed to A1221, VIN, or vehicle (DMSO) in the F1 generation, and a second exposure (same or different) was administered to the F4 generation. Anxiety-like behavior was measured in the Open Field test, Light:Dark box, and Elevated Plus Maze in the F1, F3, F4, and F6 generations. Serum concentrations of estradiol and corticosterone were analyzed.

RESULTS

Behavioral effects were not detectable in the F1 generation but emerged and became more robust across generations. Rats with ancestral VIN exposure demonstrated less anxiety-like behavior in the F3 paternal line in comparison with controls. Rats exposed to ancestral then prenatal A1221/VIN and VIN/A1221 had more anxiety-like behavior in the F4 maternal line, and those with two ancestral hits of VIN/VIN had more anxiety in the F6 paternal line, in comparison with controls.

DISCUSSION

Our findings suggest that anxiety-like behavioral phenotypes can manifest in rats following germline exposure to EDCs and that subsequent exposures across generations can intensify these effects in a lineage-dependent manner. https://doi.org/10.1289/EHP15621.

Two Hits of EDCs Three Generations Apart: Evaluating Multigenerational Anxiety-Like Behavioral Phenotypes in Male Rats Exposed to Aroclor 1221 and Vinclozolin

BACKGROUND

Increasing evidence supports an association of endocrine-disrupting chemical (EDC) exposures with adverse biological effects in humans and wildlife. Recent studies reveal that health consequences of environmental exposures may persist or emerge across generations. This creates a dual conundrum: that we are exposed to contemporary environmental chemicals overlaid upon the inheritance of our ancestors' exposure profiles. Even when legacy EDCs are phased out, they may remain relevant due to persistence in the environment together with intergenerational inheritance of their adverse biological effects. Thus, we all possess a body burden of legacy contaminants, and we are also increasingly exposed to new generations of EDCs.

OBJECTIVES

We assessed the effects of direct and ancestral exposures to EDCs across six generations on anxiety-like behaviors in male rats using our "two hits, three generations apart" multigenerational EDC exposure experimental model. We investigated two classes of EDCs with distinct hormonal actions and historical use-the weakly estrogenic polychlorinated biphenyl (PCB) mixture Aroclor 1221 (A1221) and the anti-androgenic fungicide vinclozolin (VIN)-in both the maternal and paternal line. We also determined if a hormonal mechanism drives these effects across generations.

METHODS

Rats were gestationally exposed to A1221, VIN, or vehicle [dimethyl sulfoxide (DMSO)] in the F1 generation. Three generations later, the F4 generation was given the same or a different exposure. Anxiety-like behavior was measured in the open field test, light:dark box, and elevated plus maze across generations. Serum was collected at the end of the experiment, and concentrations of estradiol and corticosterone were analyzed.

RESULTS

Although direct exposure did not affect behavior in F1 males, ancestral exposure to VIN decreased anxiety-like behavior in the F3 paternal line compared to vehicle. In the F4 paternal line, ancestral A1221 followed by direct exposure to VIN increased anxiety-like behavior compared to controls. In the F6 maternal line, relative to vehicle, the double ancestral hits of A1221/VIN decreased anxiety-like behavior. Serum hormones weakly predicted behavioral changes in the F4 paternal line and were modestly affected in the F4 and F6 maternal lines.

DISCUSSION

Our data suggest that anxiety-like behavioral phenotypes emerge transgenerationally in male rats in response to EDC exposure and that multiple hits of either the same or a different EDC can increase the impact in a lineage-specific manner. https://doi.org/10.1289/EHP15684.

Association Between Dietary Fiber Intake and Sleep Disorders: Based on the NHANES Database

OBJECTIVE

Utilizing data from the National Health and Nutrition Examination Survey (NHANES) database, the primary objective of this investigation was to examine the relationship between dietary fiber intake (DFI) and sleep disorders.

METHODS

For analysis, data from three consecutive cycles of NHANES (2009-2014) were pooled. The independent variable of interest was DFI, while the dependent variable was sleep disorders. Weighted logistic regression was employed to model the relationship between the two variables. Subgroup analyses were conducted, stratified, and adjusted to explore the association between DFI and sleep disorders.

RESULTS

This study encompassed a cohort of 14,360 samples. Logistic regression results revealed a significant inverse association between higher DFI and the risk of sleep disorders (OR: 0.99, 95% CI: 0.98-1.00, p = 0.005). Stratified analysis demonstrated significant interactive effects of gender and physical activity on the association between DFI and sleep disorders (interaction p = 0.017, p = 0.061). Quartile-stratified analysis of DFI showed that in the crude model, Q4 exhibited a significant protective impact against sleep disorders (OR: 0.76, 95% CI: 0.59-0.97, p = 0.026). In model I, which adjusted for demographic characteristics only, Q3 (OR: 0.74, 95% CI: 0.56-0.98, p = 0.036) and Q4 (OR: 0.70, 95% CI: 0.55-0.90, p = 0.006) had significant protective effects on sleep disorders. Additionally, gender subgroup analysis revealed that DFI had a significant impact on the female population, particularly in postmenopausal women, and was more pronounced in subjects with BMI > 30 kg/m2 (p = 0.011). Within the physical activity subgroup, there was a certain effect of DFI on improving sleep disorders in individuals with low activity intensity.

CONCLUSION

Increasing DFI had a protective effect in reducing the risk of sleep disorders. This protective effect may be more pronounced in the female population and individuals with low physical intensity.

Distinct Impacts of Prenatal and Postnatal Phthalate Exposure on Behavioral and Emotional Development in Children Aged 1.5 to 3 Years

Development is a continuous process, but few studies have assessed the simultaneous impact of prenatal and postnatal phthalate exposure on children's behavioral and emotional development. A total of 491 mother-child pairs from the general population in southern Taiwan were studied from 2021 to 2022. Urinary concentrations of bisphenol A (BPA) and phthalate metabolites-mono-ethyl phthalate (MEP), mono-n-butyl phthalate (MnBP), mono-benzyl phthalate (MBzP), and mono-2-ethylhexyl phthalate (MEHP)-were measured in pregnant mothers during the second trimester and in their corresponding children aged 1.5 to 3 years. Behavioral symptoms in children were evaluated using the Child Behavior Checklist (CBCL). Odds ratios (ORs) represent a 1-unit increase in log10-transformed creatinine-corrected maternal urine concentrations. Prenatal maternal urinary MnBP levels were associated with total problems (OR = 19.32, 95% CI: 1.80-43.13, p = 0.04), anxiety (OR = 33.58, 95% CI: 2.16-521.18, p = 0.01), and sleep problems (OR = 41.34, 95% CI: 1.04-1632.84, p = 0.04) in children. Additionally, urinary MnBP levels in children correlated with total problems (OR = 7.06, 95% CI: 1.01-49.05, p = 0.04) and internalizing problems (OR = 11.04, 95% CI: 1.27-95.72, p = 0.01). These findings suggest that prenatal and postnatal exposure to dibutyl phthalate (DBP), metabolized as MnBP, distinctly affects children's behavioral development.

Developmental origins of Parkinson's disease risk: perinatal exposure to the organochlorine pesticide dieldrin leads to sex-specific DNA modifications in critical neurodevelopmental pathways in the mouse midbrain

Epidemiological studies show that exposure to the organochlorine pesticide dieldrin is associated with an increased risk of Parkinson's disease (PD). Animal studies support a link between developmental dieldrin exposure and increased neuronal susceptibility in the α-synuclein preformed fibril and MPTP models in adult male C57BL/6 mice. In a previous study, we showed that developmental dieldrin exposure was associated with sex-specific changes in DNA modifications within genes related to dopaminergic neuron development and maintenance at 12 wk of age. Here, we used capture hybridization-sequencing with custom baits to interrogate DNA modifications across the entire genetic loci of the previously identified genes at multiple time points-birth, 6, 12, and 36 wk old. We identified largely sex-specific dieldrin-induced changes in DNA modifications at each time point that annotated to pathways important for neurodevelopment, potentially related to critical steps in early neurodevelopment, dopaminergic neuron differentiation, synaptogenesis, synaptic plasticity, and glial-neuron interactions. Despite large numbers of age-specific DNA modifications, longitudinal analysis identified a small number of differential modification of cytosines with dieldrin-induced deflection of epigenetic aging. The sex-specificity of these results adds to evidence that sex-specific responses to PD-related exposures may underly sex-specific differences in disease. Overall, these data support the idea that developmental dieldrin exposure leads to changes in epigenetic patterns that persist after the exposure period and disrupt critical neurodevelopmental pathways, thereby impacting risk of late-life diseases, including PD.

Microglial responses to inflammatory challenge in adult rats altered by developmental exposure to polychlorinated biphenyls in a sex-specific manner

Polychlorinated biphenyls are ubiquitous environmental contaminants linkedc with peripheral immune and neural dysfunction. Neuroimmune signaling is critical to brain development and later health; however, effects of PCBs on neuroimmune processes are largely undescribed. This study extends our previous work in neonatal or adolescent rats by investigating longer-term effects of perinatal PCB exposure on later neuroimmune responses to an inflammatory challenge in adulthood. Male and female Sprague-Dawley rats were exposed to a low-dose, environmentally relevant, mixture of PCBs (Aroclors 1242, 1248, and 1254, 1:1:1, 20 μg / kg dam BW per gestational day) or oil control during gestation and via lactation. Upon reaching adulthood, rats were given a mild inflammatory challenge with lipopolysaccharide (LPS, 50 μg / kg BW, ip) or saline control and then euthanized 3 hours later for gene expression analysis or 24 hours later for immunohistochemical labeling of Iba1+ microglia. PCB exposure did not alter gene expression or microglial morphology independently, but instead interacted with the LPS challenge in brain region- and sex-specific ways. In the female hypothalamus, PCB exposure blunted LPS responses of neuroimmune and neuromodulatory genes without changing microglial morphology. In the female prefrontal cortex, PCBs shifted Iba1+ cells from reactive to hyperramified morphology in response to LPS. Conversely, in the male hypothalamus, PCBs shifted cell phenotypes from hyperramified to reactive morphologies in response to LPS. The results highlight the potential for long-lasting effects of environmental contaminants that are differentially revealed over a lifetime, sometimes only after a secondary challenge. These neuroimmune endpoints are possible mechanisms for PCB effects on a range of neural dysfunction in adulthood, including mental health and neurodegenerative disorders. The findings suggest possible interactions with other environmental challenges that also influence neuroimmune systems.

The contribution of environmental pollutants to the risk of autism and other neurodevelopmental disorders: A systematic review of case-control studies

Exposure to environmental pollutants, such as metals, pesticides, and air pollutants during early life, is a risk factor for neurodevelopmental disorders (NDDs), including Autism Spectrum Disorder (ASD). Our systematic review aimed to select and summarize more recent case-control studies that examined the association between prenatal and early postnatal exposure to environmental pollutants and NDDs. We searched five databases (Web of Science, PubMed, Embase, Scopus, Ovid), screened 2261 records, and included 24 eligible case-control studies. Meta-analyses were conducted on subgroups of at least three studies that shared both the outcome and the exposure. A noteworthy discovery from this literature review is the existence of non-linear or non-monotonic dose-response relationships between the exposure to certain metals and the risk of ASD. The meta-analysis revealed a significant association between exposure to particular matter (PM)10 during the first year of life and the risk of ASD. Overall, studies included in our systematic review indicate that exposure to several pollutants within the first three years of life was significantly associated with the risk of NDDs.

Regrettable Substitutes and the Brain: What Animal Models and Human Studies Tell Us about the Neurodevelopmental Effects of Bisphenol, Per- and Polyfluoroalkyl Substances, and Phthalate Replacements

In recent decades, emerging evidence has identified endocrine and neurologic health concerns related to exposure to endocrine-disrupting chemicals (EDCs), including bisphenol A (BPA), certain per- and polyfluoroalkyl compounds (PFASs), and phthalates. This has resulted in consumer pressure to remove these chemicals from the market, especially in food-contact materials and personal care products, driving their replacement with structurally or functionally similar substitutes. However, these "new-generation" chemicals may be just as or more harmful than their predecessors and some have not received adequate testing. This review discusses the research on early-life exposures to new-generation bisphenols, PFASs, and phthalates and their links to neurodevelopmental and behavioral alterations in zebrafish, rodents, and humans. As a whole, the evidence suggests that BPA alternatives, especially BPAF, and newer PFASs, such as GenX, can have significant effects on neurodevelopment. The need for further research, especially regarding phthalate replacements and bio-based alternatives, is briefly discussed.

Developmental origins of Parkinson's disease risk: perinatal exposure to the organochlorine pesticide dieldrin leads to sex-specific DNA modifications in critical neurodevelopmental pathways in the mouse midbrain

Epidemiological studies show that exposure to the organochlorine pesticide dieldrin is associated with increased risk of Parkinson's disease (PD). Animal studies support a link between developmental dieldrin exposure and increased neuronal susceptibility in the α-synuclein preformed fibril (α-syn PFF) and MPTP models in adult male C57BL/6 mice. In a previous study, we showed that developmental dieldrin exposure was associated with sex-specific changes in DNA modifications within genes related to dopaminergic neuron development and maintenance at 12 weeks of age. Here, we used capture hybridization-sequencing with custom baits to interrogate DNA modifications across the entire genetic loci of the previously identified genes at multiple time points - birth, 6 weeks, 12 weeks, and 36 weeks old. We identified largely sex-specific dieldrin-induced changes in DNA modifications at each time point that annotated to pathways important for neurodevelopment, potentially related to critical steps in early neurodevelopment, dopaminergic neuron differentiation, synaptogenesis, synaptic plasticity, and glial-neuron interactions. Despite large numbers of age-specific DNA modifications, longitudinal analysis identified a small number of DMCs with dieldrin-induced deflection of epigenetic aging. The sex-specificity of these results adds to evidence that sex-specific responses to PD-related exposures may underly sex-specific differences in disease. Overall, these data support the idea that developmental dieldrin exposure leads to changes in epigenetic patterns that persist after the exposure period and disrupt critical neurodevelopmental pathways, thereby impacting risk of late life diseases, including PD.

Enhanced identification of endocrine disruptors through integration of science-based regulatory practices and innovative methodologies: The MERLON Project

The prevalence of hormone-related health issues caused by exposure to endocrine disrupting chemicals (EDCs) is a significant, and increasing, societal challenge. Declining fertility rates together with rising incidence rates of reproductive disorders and other endocrine-related diseases underscores the urgency in taking more action. Addressing the growing threat of EDCs in our environment demands robust and reliable test methods to assess a broad variety of endpoints relevant for endocrine disruption. EDCs also require effective regulatory frameworks, especially as the current move towards greater reliance on non-animal methods in chemical testing puts to test the current paradigm for EDC identification, which requires that an adverse effect is observed in an intact organism. Although great advances have been made in the field of predictive toxicology, disruption to the endocrine system and subsequent adverse health effects may prove particularly difficult to predict without traditional animal models. The MERLON project seeks to expedite progress by integrating multispecies molecular research, new approach methodologies (NAMs), human clinical epidemiology, and systems biology to furnish mechanistic insights and explore ways forward for NAM-based identification of EDCs. The focus is on sexual development and function, from foetal sex differentiation of the reproductive system through mini-puberty and puberty to sexual maturity. The project aims are geared towards closing existing knowledge gaps in understanding the effects of EDCs on human health to ultimately support effective regulation of EDCs in the European Union and beyond.

Association of postnatal exposure to mixture of bisphenol A, Di-n-butyl phthalate and Di-(2-ethylhexyl) phthalate with Children's IQ at 5 Years of age: Mothers and Children's environmental health (MOCEH) study

Early childhood is important for neurodevelopment, and exposure to endocrine disruptors such as bisphenol A (BPA) and phthalates in this period may cause neurodevelopmental disorders and delays. The present study examined the association between exposure to mixtures of BPA and three metabolites of phthalates in early childhood and IQ at 5 years of age. The Mother and Children's Environmental Health (MOCEH) study is a prospective birth cohort study conducted in Korea with 1751 pregnant women enrolled from 2006 to 2010. After excluding those without relevant data, 47 children were included in the final analysis. We measured children's urinary concentrations of metabolites of endocrine-disrupting chemicals (Bisphenol A, mono-(2-ethyl-5-oxohexyl) phthalate, mono-(2-ethyl-5-hydroxyhexyl) phthalate and mono-(2-ethyl-5-butyl) phthalate) at ages of 24 and 36 months. We evaluated the children's IQ with the Korean Wechsler Intelligence Test at the age of 5 years. After adjusting for potential confounders, a multiple linear regression was conducted to examine the associations between individual endocrine-disrupting chemicals and the IQ of the children. Weighted Quantile Sum (WQS) regression and quantile-based g-computation were used to assess the association between IQ at age 5 and exposure to mixtures of BPA and phthalates. In the single-chemical analyses, mono-(2-ethyl-5-butyl) phthalate exposure at 36 months was adversely associated with children's IQ (β = -4.93, 95% confidence interval (CI): -9.22, -0.64). In the WQS regression and quantile-based g-computation analyses, exposure to the mixture of BPA and phthalates was associated with lower IQ [β = -9.13 (P-value = 0.05) and β = -9.18 (P-value = 0.05), respectively]. The largest contributor to the overall association was exposure to mono-(2-ethyl-5-butyl) phthalate at 36 months. In the present study, postnatal exposure to mixtures of BPA and three metabolites of phthalates was associated with decreased IQ of children at age 5.

Cytokines as mediators of the associations of prenatal exposure to phenols, parabens, and phthalates with internalizing behaviours at age 3 in boys: A mixture exposure and mediation approach

Childhood internalizing disorders refer to inwardly focused negative behaviours such as anxiety, depression, and somatic complains. Interactions between psychosocial, genetic, and environmental risk factors adversely impact neurodevelopment and can contribute to internalizing disorders. While prenatal exposure to single endocrine disruptors (EDs) is associated with internalizing behaviours in infants, the associations with prenatal exposure to EDs in mixture remain poorly addressed. In addition, the biological mediators of EDs in mixture effects on internalizing behaviours remain unexplored. EDs do not only interfere with endocrine function, but also with immune function and inflammatory processes. Based on this body of evidence, we hypothetised that inflammation at birth is a plausible biological pathway through which prenatal exposure to EDs in mixture could operate to influence offspring internalizing behaviours. Based on the EDEN birth cohort, we investigated whether exposure to a mixture of EDs increased the odds of internalizing disorders in 459 boy infants at age 3, and whether the pro-inflammatory cytokines IL-1β, IL-6, and TNF-α measured at birth were mediators of this effect. To determine both the joint and individual associations of prenatal exposure to EDs with infant internalizing behaviours and the possible mediating role of cytokines, we used the counterfactual hierarchical Bayesian Kernel Machine Regression (BKMR) regression-causal mediation analysis. We show that prenatal exposure to a complex mixture of EDs has limited effects on internalizing behaviours in boys at age 3. We also show that IL-1β, IL-6, and TNF-α are unlikely mediators or suppressors of ED mixture effects on internalizing behaviours in boys at age 3. Further studies on larger cohorts are warranted to refine the deleterious effects of EDs in mixtures on internalizing behaviours and identify possible mediating pathways.

Is alumina suitable for solid phase extraction of catecholamines from brain tissue?

Occupational and environmental toxicology specialists find catecholamine fluctuations in brain tissue relevant for research of neurotoxicity, such as that induced by manganese or zinc, pesticides, industrial solvents, plastic, air pollution, or irradiation. Considering that catecholamine tissue concentrations are generally very low, their extraction requires a reliable and optimal method that will achieve maximum recovery and minimise other interferences. This study aimed to evaluate whether the aluminium (III) oxide (Al2O3, alumina) based cartridges designed for catecholamine isolation from plasma could be used for solid-phase extraction (SPE) of catecholamine from the brain tissue. To do that, we homogenised Wistar rat brain tissue with perchloric acid and compared three extraction techniques: SPE, the routine filtration through a 0.22 µm membrane filter, and their combination. In the extracts, we compared relative chromatographic catecholamine mobility measured with high performance liquid chromatography with electrochemical detection. Chromatographic patterns for norepinephrine and epinephrine were similar regardless of the extraction technique, which indicates that the alumina cartridge is good enough to isolate them from brain tissue. However, the dopamine pattern was unsatisfactory, and further experiments are needed to identify the issue and optimise the protocol.

Estradiol and progesterone in female reward-learning, addiction, and therapeutic interventions

Sex steroid hormones like estradiol (E2) and progesterone (P4) guide the sexual organization and activation of the developing brain and control female reproductive behavior throughout the lifecycle; importantly, these hormones modulate functional activity of not just the endocrine system, but most of the nervous system including the brain reward system. The effects of E2 and P4 can be seen in the processing of and memory for rewarding stimuli and in the development of compulsive reward-seeking behaviors like those seen in substance use disorders. Women are at increased risk of developing substance use disorders; however, the origins of this sex difference are not well understood and therapeutic interventions targeting ovarian hormones have produced conflicting results. This article reviews the contribution of the E2 and P4 in females to functional modulation of the brain reward system, their possible roles in origins of addiction vulnerability, and the development and treatment of compulsive reward-seeking behaviors.