Prenatal and breastfeeding exposure to low dose of diethylhexyl phthalate induces behavioral deficits and exacerbates oxidative stress in rat hippocampus

Gender associations between phthalate exposure and biomarkers of oxidative stress: A prospective cohort study

Previous epidemiologic research has shown that phthalate exposure in pregnant women is related to adverse birth outcomes in a sex-specific manner. However, the biological mechanism of phthalate exposure that causes these birth outcomes remains poorly defined. In this research, we investigated the association between phthalate exposure and placental oxidative stress in a large population-based cohort study, aiming to initially explore the relationship between phthalate exposure and gene expression in placental oxidative stress in a sex-specific manner. Quantitative PCR was performed to measure the expression of placental inflammatory mRNAs (HO-1, HIF1α, and GRP78) in 2469 placentae. The multiple linear regression models were used to investigate the associations between mRNA and urinary phthalate monoesters. Phthalate metabolites monomethyl phthalate (MMP) and mono-n-butyl phthalate (MBP) were positively correlated with higher HIF1α expression in placentae of male fetuses (p < .05). Mono-benzyl phthalate (MBzP) increased the expression of HO-1, HIF1α, and GRP78 in placentae of male fetuses, and mono-(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) up-regulated the expression of HIF1α and GRP78. Additionally, mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP) was negatively correlated with HO-1, HIF1α, and GRP78 in placentae of female fetuses. Maternal phthalate exposure was associated with oxidative stress variations in placental tissues. The associations were closer in the placentas of male fetuses than in that of female ones. The placenta oxidative stress is worth further investigation as a potential mediator of maternal exposure-induced disease risk in children.

Mitigating effect of ferulic acid on di-(2-ethylhexyl) phthalate-induced neurocognitive dysfunction in male rats with a comprehensive in silico survey

Di-(2-ethylhexyl) phthalate (DEHP) is the most abundant phthalate threatening public health-induced neurotoxicity. This neurotoxicity is associated with behavioral and biochemical deficits in male rats. Our study investigated the neuroprotective effect of ferulic acid (FA) on male rats exposed to DEHP. Thirty-two male Wistar rats were assigned to four groups. Group I control rats received corn oil, group II intoxicated rats received 300 mg/kg of DEHP, group III received 300 mg/kg of DEHP + 50 mg/kg of FA, and group IV received 50 mg/kg of FA, all agents administrated daily per os for 30 days. Anxiety-like behavior, spatial working memory, and recognition memory were assessed. Also, brain oxidative stress biomarkers, including brain malondialdehyde (MDA), reduced glutathione (GSH), nitric oxide (NO), superoxide dismutase (SOD), brain-derived neurotrophic factor (BDNF) as well as heme oxygenase-1 (HO-1) were measured. Moreover, brain histopathology examinations associated with immunohistochemistry determination of brain caspase-3 were also evaluated. Furthermore, docking simulation was adapted to understand the inhibitory role of FA on caspase-3 and NO synthase. Compared to DEHP-intoxicated rats, FA-treated rats displayed improved cognitive memory associated with a reduced anxious state. Also, the redox state was maintained with increased BNDF levels. These changes were confirmed by restoring the normal architecture of brain tissue and a decrement in the immunohistochemistry caspase-3. In conclusion, FA has potent antioxidant and antiapoptotic properties that confirm the neuroprotective activity of FA, with a possible prospect for its therapeutic capabilities and nutritional supplement value.

Sub-acute administration of metal-organic Framework-5 induces behavioral impairments and augments the levels of oxidative stress and inflammation in the brain of rats

Metal-organic frameworks (MOFs) are known as potential pharmaceutical carriers because of their structure. Here, we evaluated the sub-acute administrations of MOF-5 on behavioral parameters, oxidative stress, and inflammation levels in rats. Thirty-two male Wistar rats received four injections of saline or MOF-5 at different doses which were 1, 10, and 50 mg/kg via caudal vein. Y-Maze and Morris-Water Maze (MWM) tests were used to explore working memory and spatial learning and memory, respectively. The antioxidant capacity and oxidative stress level of brain samples were assessed by ferric reducing antioxidant power (FRAP) and thiobarbituric acid-reacting substance (TBARS) assay, respectively. The expression levels of GFAP, IL-1β, and TNF-α were also measured by quantitative real-time reverse-transcription PCR (qRT-PCR). Sub-acute administration of MOF-5 reduced the spatial learning and memory as well as working memory, dose-dependently. The levels of FRAP were significantly reduced in rats treated with MOF-5 at higher doses. The Malondialdehyde (MDA) levels increased at the dose of 50 mg/kg. Additionally, the expression levels of IL-1β and TNF-α were significantly elevated in the rats' brains that were treated with MOF-5. Our findings indicate that sub-acute administration of MOF-5 induces cognitive impairment dose-dependently which might be partly mediated by increasing oxidative stress and inflammation.

Di (2-ethylhexyl) phthalate alters neurobehavioral responses and oxidative status, architecture, and GFAP and BDNF signaling in juvenile rat's brain: Protective role of Coenzyme10

Di-(2-ethylhexyl) phthalate (DEHP), a phthalate plasticizer, is widely spread in the environment, presenting hazards to human health and food safety. Hence, this study examined the probable preventive role of coenzyme10 (CQ10) (10 mg/kg.b.wt) against DEHP (500 mg/kg.wt) - induced neurotoxic and neurobehavioral impacts in juvenile (34 ± 1.01g and 3 weeks old) male Sprague Dawley rats in 35-days oral dosing trial. The results indicated that CQ10 significantly protected against DEHP-induced memory impairment, anxiety, depression, spatial learning disorders, and repetitive/stereotypic-like behavior. Besides, the DEHP-induced depletion in dopamine and gamma amino butyric acid levels was significantly restored by CQ10. Moreover, CQ10 significantly protected against the exhaustion of CAT, GPx, SOD, GSH, and GSH/GSSG ratio, as well as the increase in malondialdehyde, Caspas-3, interleukin-6, and tumor necrosis factor-alpha brain content accompanying with DEHP exposure. Furthermore, CQ10 significantly protected the brain from the DEHP-induced neurodegenerative alterations. Also, the increased immunoexpression of brain-derived neurotrophic factor, not glial fibrillary acidic protein, in the cerebral, hippocampal, and cerebellar brain tissues due to DEHP exposure was alleviated with CQ10. This study's findings provide conclusive evidence that CQ10 has the potential to be used as an efficient natural protective agent against the neurobehavioral and neurotoxic consequences of DEHP.

Clostridium butyricum Alleviates DEHP Plasticizer-Induced Learning and Memory Impairment in Mice via Gut-Brain Axis

Di-(2-ethylhexyl) phthalate (DEHP) plasticizer, a well-known environmental and food pollutant, has neurotoxicity. However, it is unknown whether DEHP leads to learning and memory impairment through gut-brain axis and whether Clostridium butyricum can alleviate this impairment. Here, C57BL/6 mice were exposed to DEHP and treated with C. butyricum. Learning and memory abilities were evaluated through the Morris water maze. The levels of synaptic proteins, inflammatory cytokines, and 5-hydroxytryptamine (5-HT) were detected by immunohistochemistry or ELISA. Gut microbiota were analyzed through 16S rRNA sequencing. C. butyricum alleviated DEHP-induced learning and memory impairment and restored synaptic proteins. It significantly relieved DEHP-induced inflammation and recovered 5-HT levels. C. butyricum recovered the richness of the gut microbiota decreased by DEHP, with the Bifidobacterium genus increasing the most. Overall, C. butyricum alleviated DEHP-induced learning and memory impairment due to reduced inflammation and increased 5-HT secretion, which was partly attributed to the recovery of gut microbiota.

Neurotoxicity and the potential molecular mechanisms of mono-2-ethylhexyl phthalic acid (MEHP) in zebrafish

Mono-2-ethylhexyl phthalic acid (MEHP) is the most toxic metabolite of plasticizer di-2-ethylhexyl phthalic acid (DEHP), and there is limited information available on the effects of MEHP on neurotoxicity. This study aims to examine the neurotoxicity of MEHP and preliminarily explore its potential molecular mechanisms. We found that MEHP impeded the growth of zebrafish embryos and the neurodevelopmental-related gene expression at environmentally relevant concentrations. MEHP exposure also induces oxidative stress response and brain cell apoptosis accompanied by a decrease in acetylcholinesterase (AChE) activity in zebrafish larvae. RNA-Seq and bioinformatics analysis showed that MEHP treatment altered the nervous system, neurogenic diseases, and visual perception pathways. The locomotor activity in dark-to-light cycles and phototaxis test confirmed the abnormal neural behavior of zebrafish larvae. Besides, the immune system has produced a large number of differentially expressed genes related to neural regulation. Inflammatory factor IL1β and IL-17 signaling pathways highly respond to MEHP, indicating that inflammation caused by immune system imbalance is a potential mechanism of MEHP-induced neurotoxicity. This study expands the understanding of the toxicity and molecular mechanisms of MEHP, providing a new perspective for in-depth neurotoxicity exploration of similar compounds.

Region- and age-specific effects of perinatal phthalate exposure on developmental cell death and adult anatomy of dorsal and ventral hippocampus and associated cognitive behaviors

Humans are exposed to phthalates, a class of endocrine-disrupting chemicals used in food packaging/processing, PVC plastics, and personal care products. Gestational exposure may lead to adverse neurodevelopmental outcomes. In a rat model, perinatal exposure to an environmentally relevant mixture and dose of phthalates leads to increased developmental apoptosis in the medial prefrontal cortex (mPFC) and a subsequent reduction in neurons and in cognitive flexibility measured in adults of both sexes (Sellinger et al., 2021b; Kougias et al., 2018b). However, whether these effects generalize to other cognitive regions, like the hippocampus, is less well understood as existing studies used single phthalates at large doses, unrepresentative of human exposure. In the current study, patterns of naturally occurring cell death were first established in the dorsal and ventral hippocampal subfields (CA3 and CA1). Both dorsal and ventral CA3 reached high levels of cell death on P2 while levels in dorsal and ventral CA1 peaked on P5 in both sexes. Exposure to a phthalate mixture (0.2 and 1 mg/kg/day) throughout gestation through postnatal day 10 resulted in subtle age- and region-specific decreases in developmental cell death, however there were no significant changes in adult neuron number or associated behaviors: the Morris water maze and social recognition. Therefore, perinatal exposure to a low dose mixture of phthalates does not result in the dramatic structural and behavioral changes seen with high doses of single phthalates. This study also adds to our understanding of the distinct neurodevelopmental effects of phthalates on different brain regions.

Di(2-ethylhexyl) phthalate and microplastics cause necroptosis and apoptosis in hepatocytes of mice by inducing oxidative stress

Di(2-ethylhexyl) phthalate (DEHP) is a plasticizer and an endocrine disruptor. Microplastics (MPs) are pathogenic small plastic particles and abundant in the aqueous environment. The problem of residual hazards of plastic products is worthy of study, especially the joint exposure of a variety of plastic-related products to the toxic effect. We used 200 mg/kg DEHP and 10 mg/L MPs to establish exposure model in vivo and 2 mM DEHP and 200 μg/L MPs to establish AML12 cell exposure model in vitro. In vivo study results showed that compared with the control group (NC) group, DEHP and MPs significantly increased the contents of malondialdehyde and hydrogen peroxide, and significantly decreased the contents of glutathione and the activity of superoxide dismutase, total antioxidant capacity, catalase and glutathione peroxidase. The level of oxidative stress was further aggravated after combined exposure. The reactive oxygen species level of AML12 exposed to DEHP and MPs in vitro was significantly higher than NC group, and the combined exposure was significantly higher than the single exposure. The in vivo and in vitro also confirmed that DEHP and MPs could significantly increase the mRNA and protein levels of apoptosis markers and necroptosis markers and there was an additive effect. After N-acetylcysteine treatment in vitro, the above-mentioned oxidative stress level and cell damage decreased significantly. This study provided a reference for advocating the reduction of the mixed use of plastic products, and provided a basis for preventing the harm of plastic products residues.

Association between phthalate exposure and the risk of depressive symptoms in the adult population of the United States

Previous research has suggested an association between phthalate exposure and depressive symptoms, but the evidence is limited. Our study aimed to examine the association between phthalate exposure and the risk of depressive symptoms in the US adult population. We used data from the National Health and Nutrition Examination Survey (NHANES) from 2005 to 2018 to analyze the association between urinary phthalates and depressive symptoms. We included 11 urinary phthalate metabolites in our analysis and used the 9-item Patient Health Questionnaire (PHQ-9) to assess the presence of depression among study participants. Participants were divided into quartiles for each urinary phthalate metabolite, and we evaluated the association using a generalized linear mixed model with a logit link and binary distribution. A total of 7340 participants were included in the final analysis. After controlling for potential confounders, we found a positive association between the molar sum of di (2-ethylhexyl) phthalate (DEHP) metabolites and depressive symptoms, with an odds ratio of 1.30 (95% CI = 1.02-1.66) for the highest compared to the lowest quartile. In addition, we found positive associations of mono (2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) and mono (2-ethyl-5-carboxypentyl) phthalate (MECPP) with depressive symptoms, with odds ratios of 1.43 (95% CI = 1.12-1.81, p for trend = 0.02) and 1.44 (95% CI = 1.13-1.84, p for trend = 0.02), respectively, for the highest compared to the lowest quartile. In conclusion, this study is the first to identify a positive association between DEHP metabolites and the risk of depressive symptoms in the general adult population in the United States.

Urinary di-(2-ethylhexyl) phthalate metabolites are independently related to serum neurofilament light chain, a biomarker of neurological diseases, in adults: results from NHANES 2013-2014

Di (2-ethylhexyl) phthalate (DEHP) is a chemical commonly used in the manufacturing of plastics and can pose human health risks, including endocrine disruption, reproductive toxicity, and potential carcinogenic effects. Children may be particularly vulnerable to the harmful effects of DEHP. Early exposure to DEHP has been linked to potential behavioral and learning problems. However, there are no reports to date on whether DEHP exposure in adulthood has neurotoxic effects. Serum neurofilament light chain (NfL), a protein released into the blood after neuroaxonal damage, has been shown to be a reliable biomarker for many neurological diseases. To date, no study has examined the relationship between DEHP exposure and NfL. For the present study, we selected 619 adults (aged ≥ 20 years) from the 2013-2014 National Health and Nutrition Examination Survey (NHANES) to examine the association between urinary DEHP metabolites and serum NfL. We reported higher urinary levels of ln-mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), ln-mono(2-ethyl-5-oxohexyl) phthalate (MEOHP), and ln-mono(2-ethyl-5-carboxypentyl) phthalate (MECPP), and ln-ΣDEHP levels were associated with higher serum levels of ln-NfL (ΣDEHP: β-coefficient = 0. 075; S.E. = 0.026; P = 0.011). When we divided ΣDEHP into quartiles, mean NfL concentrations increased with quartiles of MEHHP (P for trend = 0.023). The association was more pronounced in males, non-Hispanic white race, higher income, and BMI < 25. In conclusion, higher DEHP exposure was positively associated with higher serum NfL in adults from NHANES 2013-2014. If this finding is causal, it is possible that DEHP exposure in adulthood may also induce neurological damage. Although the causality of this observation and the clinical significance are uncertain, our findings suggest that additional research is needed on DEHP exposure, serum NfL, and neurological disease in adults.

Cognitive and hippocampal effects of adult male mice exposure to environmentally relevant doses of phthalates

We recently showed that chronic exposure of adult male mice to environmental doses of DEHP alone or in a phthalate mixture altered blood brain barrier integrity and induced an inflammatory profile in the hippocampus. Here, we investigate whether such exposure alters hippocampus-dependent behavior and underlying cellular mechanisms. Adult C57BL/6 J male mice were continuously exposed orally to the vehicle or DEHP alone (5 or 50 μg/kg/d) or to DEHP (5 μg/kg/d) in a phthalate mixture. In the Morris water maze, males showed reduced latencies across days to find the platform in the cue and spatial reference memory tasks, regardless of their treatment group. In the probe test, DEHP-50 exposed males displayed a higher latency to find the platform quadrant. In the temporal order memory test, males exposed to DEHP alone or in a phthalate mixture were unable to discriminate between the most recently and previously seen objects. They also displayed reduced ability to show a preference for the new object in the novel object recognition test. These behavioral alterations were associated with a lowered dendritic spine density and protein levels of glutamate receptors and postsynaptic markers, and increased protein levels of the presynaptic synaptophysin in the hippocampus. Metabolomic analysis of the hippocampus indicated changes in amino acid levels including reduced tryptophan and L-kynurenine and elevated NAD + levels, respectively, a precursor, intermediate and endproduct of the kynurenine pathway of tryptophan metabolism. Interestingly, the protein amounts of the xenobiotic aryl hydrocarbon receptor, a target of this metabolic pathway, were elevated in the CA1 area. These data indicate that chronic exposure of adult male mice to environmental doses of DEHP alone or in a phthalate mixture impacted hippocampal function and structure, associated with modifications in amino acid metabolites with a potential involvement of the kynurenine pathway of tryptophan metabolism.

Dose-dependent toxic effects of di-(2-ethylhexyl) phthalate in male rats: Focus on behavioral alterations and inducing TLR4/NF-κB signaling pathway

Di -(2-ethylhexyl) phthalate (DEHP) is a widely used phthalate that possesses a public health concern. Different concentrations of DEHP, including 50, 300, and 750 mg/kg, were administrated orally for 28 days in male rats. Body weight and vital organs weight were measured as well as anxiety-like behavior, short and long-term memory were investigated. Brain inflammatory cytokines, including IL-1β, TLR4, NF-κB, TNF-α, and IL1-6, were assessed. Brain caspase-3, neuropeptide-Y (NPY), and brain histopathology were also evaluated. DEHP triggers the release of pro-inflammatory cytokines via inducing the nuclear translocation of the signaling pathway; TLR 4/ NF-κB leads to cognitive impairment and neurodegeneration, which is confirmed by the impaired brain architecture. Also, DEHP upgrades the expression levels of brain caspase-3 and NPY. In conclusion, exposure to high doses of DEHP persuades great toxicity visualized by behavioral, biochemical, and histological impairments when compared to the low dose.

Association between urinary phthalate metabolites and hyperuricemia in US adults

Phthalate metabolites have been detected from urine in most of the US population and have become a public health problem. However, the association between phthalate metabolites and hyperuricemia has been scarcely studied so far. We aimed to evaluate if phthalate metabolites were associated with hyperuricemia in US adults. A total of 8816 participants of the National Health and Nutrition Examination Survey (NHANES) from 2005 to 2018 were included in our study. We used multivariable logistic regression models and restricted cubic spline (RCS) models to explore the association between urinary phthalate metabolites and hyperuricemia. Then, stratified analyses were conducted by sex and age. The prevalence of hyperuricemia in the study sample was 20.35%. Compared to the lowest quantile, the odds ratios (ORs) and 95% confidence intervals (CIs) for hyperuricemia were all statistically significant in following phthalate metabolites: 1.34 (1.13-1.58) for the second quartile in Mono-isobutyl phthalate (MiBP), 1.21 (1.01-1.46) for the highest quartile in Mono-(carboxyoctyl) phthalate (MCOP), 0.66 (0.56-0.76) for the second quartile in Mono-(2-ethyl)-hexyl phthalate (MEHP), 1.22 (1.05-1.43) for quartile 2 in Benzyl butyl phthalate (ΣBBP), and 1.43 (1.22-1.66) for the third quartile in high molecular-weight phthalate (ΣHigh MWP), respectively. Our results indicate that several urinary phthalate metabolites are positively associated with the odds of hyperuricemia.

Lycopene ameliorates DEHP exposure-induced renal pyroptosis through the Nrf2/Keap-1/NLRP3/Caspase-1 axis

Di (2-ethylhexyl) phthalate (DEHP) is commonly used as a plasticizer in plastic products, and due to its unique chemical composition, it frequently dissolves and enters the environment. Lycopene as a natural carotenoid has been shown to have powerful antioxidant capacity and strong kidney protection. This study aimed to investigate the role of the interplay between oxidative stress and the classical pyroptosis pathway in LYC alleviating DEHP-induced renal injury. ICR mice were given DEHP (500 mg/kg/d or 1000 mg/kg/d) and/or LYC (5 mg/kg/d) for 28 days to explore the underlying mechanisms of this hypothesis. Our results indicated that DEHP caused the shedding of renal tubular epithelial cells, increased the content of kidney injury molecule-1 (Kim-1) and neutrophil gelatinase-associated lipocalin (NGAL) in the tissue, the decrease of antioxidant activity markers and the increase of oxidative stress indexes. It is gratifying that LYC alleviates DEHP-induced renal injury. The expression of nuclear factor erythrocyte 2-related factor 2 (Nrf2) and its downstream target genes is improved in DEHP induced renal injury through LYC mediated protection. Meanwhile, LYC supplementation can inhibit DEHP-induced Caspase-1/NLRP3-dependent pyroptosis and inflammatory responses. Taken together, DEHP administration resulted in nephrotoxicity, but these changes ameliorated by LYC may through crosstalk between the Nrf2/Keap-1/NLRP3/Caspase-1 pathway. Our study provides new evidence that LYC protects against kidney injury caused by DEHP.

Impact of endocrine disruptors from mother's diet on immuno-hormonal orchestration of brain development and introduction of the virtual human twin tool

Diet has long been known to modify physiology during development and adulthood. However, due to a growing number of manufactured contaminants and additives over the last few decades, diet has increasingly become a source of exposure to chemicals that has been associated with adverse health risks. Sources of food contaminants include the environment, crops treated with agrochemicals, inappropriate storage (e.g., mycotoxins) and migration of xenobiotics from food packaging and food production equipment. Hence, consumers are exposed to a mixture of xenobiotics, some of which are endocrine disruptors (EDs). The complex interactions between immune function and brain development and their orchestration by steroid hormones are insufficiently understood in human populations, and little is known about the impact on immune-brain interactions by transplacental fetal exposure to EDs via maternal diet. To help to identify the key data gaps, this paper aims to present (a) how transplacental EDs modify immune system and brain development, and (b) how these mechanisms may correlate with diseases such as autism and disturbances of lateral brain development. Attention is given to disturbances of the subplate, a transient structure of crucial significance in brain development. Additionally, we describe cutting edge approaches to investigate the developmental neurotoxicity of EDs, such as the application of artificial intelligence and comprehensive modelling. In the future, highly complex investigations will be performed using virtual brain models constructed using sophisticated multi-physics/multi-scale modelling strategies based on patient and synthetic data, which will enable a greater understanding of healthy or disturbed brain development.

Exposure to di (2-ethylhexyl) phthalate causes locomotor increase and anxiety-like behavior via induction of oxidative stress in brain

Di (2-ethylhexyl) phthalate (DEHP) is one of the most prevalent xenoestrogen endocrine disruptor in daily life. A growing number of studies showed that DEHP could exhibit long-term adverse health effects on the human body, particularly in the liver, kidneys, heart and reproductive systems. However, the impact of oral intake of DEHP on the nervous system is extremely limited. In the present study, the adult C57BL/6J male mice were intragastrically administered with two dosages of DEHP for 35 days. The behavioral parameters were assessed using the elevated plus maze and open-field test. The mRNA expression levels of neuropeptides and the oxidative stress-associated proteins were detected by qPCR and western blot seperately. The histopathologic alterations of the brain were observed by H&E and Nissl staining. The results demonstrated that DEHP exposure could result in neurobehavioral impairments such as locomotor increase and anxiety-like behavior. Furthermore, pathological damages were clearly observed in the cerebral cortex and hippocampus, accompanied by a decrease in neuropeptides and an increase in oxidative stress, which were all positively correlated with the dose of DEHP. Together, these findings provide valuable clues into the DEHP-induced neurotoxicity.

An insight into sex-specific neurotoxicity and molecular mechanisms of DEHP: A critical review

Di-2-Ethylhexyl Phthalate (DEHP) is often used as an additive in polyvinyl chloride (PVC) to give plastics flexibility, which makes DEHP widely used in food packaging, daily necessities, medical equipment, and other products. However, due to the unstable combination of DEHP and polymer, it will migrate to the environment in the materials and eventually contact the human body. It has been recorded that low-dose DEHP will increase neurotoxicity in the nervous system, and the human health effects of DEHP have been paid attention to because of the extensive exposure to DEHP and its high absorption during brain development. In this study, we review the evidence that DEHP exposure is associated with neurodevelopmental abnormalities and neurological diseases based on human epidemiological and animal behavioral studies. Besides, we also summarized the oxidative damage, apoptosis, and signal transduction disorder related to neurobehavioral abnormalities and nerve injury, and described the potential mechanisms of neurotoxicity caused by DEHP. Overall, we found exposure to DEHP during the critical developmental period will increase the risk of neurobehavioral abnormalities, depression, and autism spectrum disorders. This effect is sex-specific and will continue to adulthood and even have an intergenerational effect. However, the research results on the sex-dependence of DEHP neurotoxicity are inconsistent, and there is a lack of systematic mechanisms research as theoretical support. Future investigations need to be carried out in a large-scale population and model organisms to produce more consistent and convincing results. And we emphasize the importance of mechanism research, which can enhance the understanding of the environmental and human health risks of DEHP exposure.

Prenatal stress induces a depressive-like phenotype in adolescent rats: The key role of TGF-β1 pathway

Stressful experiences early in life, especially in the prenatal period, can increase the risk to develop depression during adolescence. However, there may be important qualitative and quantitative differences in outcome of prenatal stress (PNS), where some individuals exposed to PNS are vulnerable and develop a depressive-like phenotype, while others appear to be resilient. PNS exposure, a well-established rat model of early life stress, is known to increase vulnerability to depression and a recent study demonstrated a strong interaction between transforming growth factor-β1 (TGF-β1) gene and PNS in the pathogenesis of depression. Moreover, it is well-known that the exposure to early life stress experiences induces brain oxidative damage by increasing nitric oxide levels and decreasing antioxidant factors. In the present work, we examined the role of TGF-β1 pathway in an animal model of adolescent depression induced by PNS obtained by exposing pregnant females to a stressful condition during the last week of gestation. We performed behavioral tests to identify vulnerable or resilient subjects in the obtained litters (postnatal day, PND &gt; 35) and we carried out molecular analyses on hippocampus, a brain area with a key role in the pathogenesis of depression. We found that female, but not male, PNS adolescent rats exhibited a depressive-like behavior in forced swim test (FST), whereas both male and female PNS rats showed a deficit of recognition memory as assessed by novel object recognition test (NOR). Interestingly, we found an increased expression of type 2 TGF-β1 receptor (TGFβ-R2) in the hippocampus of both male and female resilient PNS rats, with higher plasma TGF-β1 levels in male, but not in female, PNS rats. Furthermore, PNS induced the activation of oxidative stress pathways by increasing inducible nitric oxide synthase (iNOS), NADPH oxidase 1 (NOX1) and NOX2 levels in the hippocampus of both male and female PNS adolescent rats. Our data suggest that high levels of TGF-β1 and its receptor TGFβ-R2 can significantly increase the resiliency of adolescent rats to PNS, suggesting that TGF-β1 pathway might represent a novel pharmacological target to prevent adolescent depression in rats.

Hippocampal AMPA receptors mediate the impairment of spatial learning and memory in prenatally stressed offspring rats

Numerous studies have shown that prenatal stress (PS) induces learning and memory deficits in offspring, yet the specific mechanisms and effective interventions remain limited. Chewing has been known as one of the active coping strategies to suppress stress, but its effects during PS on learning and memory are unknown. The purpose of this study was to investigate the role of hippocampal AMPA receptors in the adverse effects of PS on spatial learning and memory, and whether chewing during PS could prevent these effects in prenatally stressed adult offspring rats. Prenatal restraint stress with or without chewing to dams during the day 11-20 of pregnancy was used to analyze the impact of different treatments for offspring. The spatial learning and memory were tested by the Morris water maze. The mRNA and protein expression of AMPA receptors in the hippocampus were measured by qRT-PCR and Western blot, respectively. The methylation of AMPA receptors was detected by bisulfite sequencing PCR. Our results revealed that PS impaired spatial learning acquisition and memory retrieval in adult offspring rats, but chewing could relieve this effect. Hippocampal GluA1-4 expression was significantly reduced in prenatally stressed offspring, while there were no changes in the methylation level of GluA2 and GluA4 promoters. Moreover, chewing increased PS-induced suppression of AMPA receptors in the hippocampus. In short, hippocampal AMPA receptors mediate the impairment of spatial learning and memory in prenatally stressed offspring, whereas chewing during PS could ameliorate PS-induced memory deficits.

Effects of Di-2-Ethylhexyl Phthalate on Central Nervous System Functions: A Narrative Review

BACKGROUND

Phthalates are widely used in the plastics industry. Di-2-Ethylhexyl Phthalate (DEHP) is one of the most important phthalate metabolites that disrupt the function of endocrine glands. Exposure to DEHP causes numerous effects on animals, humans, and the environment. Low doses of DEHP increase neurotoxicity in the nervous system that has arisen deep concerns due to the widespread nature of DEHP exposure and its high absorption during brain development.

OBJECTIVE

In this review article, we evaluated the impacts of DEHP exposure from birth to adulthood on neurobehavioral damages. Then, the possible mechanisms of DEHP-induced neurobehavioral impairment were discussed.

METHODOLOGY

Peer-reviewed articles were extracted through Embase, PubMed, and Google Scholar till the year 2021.

RESULTS

The results showed that exposure to DEHP during pregnancy and infancy leads to memory loss and irreversible nervous system damage.

CONCLUSION

Overall, it seems that increased levels of oxidative stress and inflammatory mediators possess a pivotal role in DEHP-induced neurobehavioral impairment.