Prenatal Exposure to Bisphenol A and/or Diethylhexyl Phthalate Impacts Brain Monoamine Levels in Rat Offspring.

This study examines the sex-specific effects of gestational exposure (days 6-21) to endocrine-disrupting chemicals such as bisphenol A (BPA), diethylhexyl phthalate (DEHP), or their combination on brain monoamine levels that play an important role in regulating behavior. Pregnant Sprague-Dawley rats were orally administered saline, low doses (5 µg/kg BW/day) of BPA or DEHP, and their combination or a high dose (7.5 mg/kg BW/day) of DEHP alone or in combination with BPA during pregnancy. The offspring were subjected to a behavioral test and sacrificed in adulthood, and the brains were analyzed for neurotransmitter levels. In the paraventricular nucleus, there was a marked reduction in dopamine levels (p < 0.01) in male offspring from the BPA, DEHP, and B + D (HD) groups, which correlated well with their shock probe defensive burying times. Neurotransmitter changes in all brain regions examined were significant in female offspring, with DEHP (HD) females being affected the most, followed by the B + D groups. BPA and/or DEHP (LD) increased monoamine turnover in a region-specific manner in male offspring (p < 0.05). Overall, prenatal exposure to BPA, DEHP, or their combination alters monoamine levels in a brain region-specific, sex-specific, and dose-dependent manner, which could have implications for their behavioral and neuroendocrine effects.

Prenatal diethylhexylphthalate exposure disturbs adult Leydig cell function via epigenetic downregulation of METTL4 expression in male rats.

Prenatal exposure to diethylhexyl phthalate (DEHP) has been linked with a decline in testosterone levels in adult male rats, but the underlying mechanism remains unclear. We investigated the potential epigenetic regulation, particularly focusing on N6-methyladenosine (m6A) modification, as a possible mechanism. Dams were gavaged with DEHP (0, 10, 100, and 750 mg/kg/day) from gestational day 14 to day 21. The male offspring were examined at the age of 56 days. Prenatal DEHP administration at 750 mg/kg/day caused a decline in testosterone concentrations, an elevation in follicle-stimulating hormone, a downregulated expression of CYP11A1 HSD3B2, without affecting Leydig cell numbers. Interestingly, Methyltransferase Like 4 (METTL4), an m6A methyltransferase, was downregulated, while there were no changes in METTL3 and METTL14. Moreover, CYP11A1 showed m6A reduction in response to prenatal DEHP exposure. Additionally, METTL4 expression increased postnatally, peaking in adulthood. Knockdown of METTL4 resulted in the downregulation of CYP11A1 and HSD3B2 and an increase in SCARB1 expression. Furthermore, the increase in autophagy protection in adult Leydig cells induced by prenatal DEHP exposure was not affected by 3-methyladenosine (3MA) treatment, indicating a potential protective role of autophagy in response to DEHP exposure. In conclusion, prenatal DEHP exposure reduces testosterone by downregulating CYP11A1 and HSD3B2 via m6A epigenetic regulation and induction of autophagy protection in adult Leydig cells as a response to DEHP exposure.

Diethylhexyl phthalate exposure amplifies oxidant and inflammatory response in fetal hyperglycemia model predisposing insulin resistance in zebrafish embryos.

Exposure of zebrafish embryos to glucose is a suitable model for the fetal hyperglycemia seen in gestational diabetes. Diethylhexyl phthalate (DEHP), which is considered an endocrine-disrupting chemical, is one of the most common phthalate derivatives used in stretching plastic and is encountered in every area where plastic is used in daily life. In the present study, the effects of DEHP on pathways related to insulin resistance and obesity were examined in zebrafish embryos exposed to glucose as a fetal hyperglycemia model. Zebrafish embryos were exposed to DEHP, glucose, and glucose + DEHP for 72 h post-fertilization (hpf), and developmental parameters and locomotor activities were monitored. At 72 hpf ins, lepa, pparγ, atf4a, and il-6 expressions were determined by RT-PCR. Glucose, lipid peroxidation (LPO), nitric oxide (NO) levels, glutathione S-transferase (GST), superoxide dismutase (SOD), and acetylcholine esterase (AChE) activities were measured spectrophotometrically. Compared with the control group, glucose, LPO, GST activity, il6, and atf4a expressions increased in all exposure groups, while body length, locomotor, and SOD activities decreased. While AChE activity decreased in the DEHP and glucose groups, it increased in the glucose + DEHP group. Although glucose exposure increased pparγ and lepa expressions, DEHP significantly decreased the expressions of pparγ and lepa both in the DEHP and glucose + DEHP groups. Our findings showed that DEHP amplified oxidant and inflammatory responses in this fetal hyperglycemia model, predisposing insulin resistance in zebrafish embryos.

Repeated Human Exposure to Semivolatile Organic Compounds by Inhalation: Novel Protocol for a Nonrandomized Study.

BACKGROUND: Semivolatile organic compounds (SVOCs) comprise several different chemical families used mainly as additives in many everyday products. SVOCs can be released into the air as aerosols and deposit on particulate matter during use by dispersion, evaporation, or abrasion. Phthalates are SVOCs of growing concern due to their endocrine-disrupting effects. Human data on the absorption, distribution, metabolism, and excretion (ADME) of these compounds upon inhalation are almost nonexistent. OBJECTIVE: The goal of this study is to develop a method for repeated inhalation exposures to SVOCs to characterize their ADME in humans. METHODS: We will use diethylhexyl phthalate (DEHP), a major indoor air pollutant, as a model SVOC in this novel protocol. The Swiss official Commission on Ethics in Human Research, Canton de Vaud, approved the study on October 14, 2020 (project-ID 2020-01095). Participants (n=10) will be repeatedly exposed (2 short daily exposures over 4 days) to isotope-labeled DEHP (DEHP-d4) to distinguish administered exposures from background exposures. DEHP-d4 aerosols will be generated with a small, portable, aerosol-generating device. Participants will inhale DEHP-d4-containing aerosols themselves with this device at home. Air concentrations of the airborne phthalates will be less than or equal to their occupational exposure limit (OEL). DEHP-d4 and its metabolites will be quantified in urine and blood before, during, and after exposure. RESULTS: Our developed device can generate DEHP-d4 aerosols with diameters of 2.5 µm or smaller and a mean DEHP-d4 mass of 1.4 (SD 0.2) µg per puff (n=6). As of May 2023, we have enrolled 5 participants. CONCLUSIONS: The portable device can be used to generate phthalate aerosols for repeated exposure in human studies. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/51020.

Tissue-specific accumulation of DEHP and involvement of endogenous arachidonic acid in DEHP-induced spleen information and injury.

The plasticizer Diethylhexyl phthalate (DEHP), one of the most common contaminants, is widely detected in environmental and biological samples. However, the accumulation of DEHP in tissue and the molecular mechanisms underlying its physiological damage in the spleen of aquatic organisms have not yet been reported. In this study, gas chromatography-mass spectrometry (GC-MS), histology and multi-omics analysis were used to investigate DEHP exposure-induced alterations in transcriptomic profiles and metabolic network of zebrafish model. After exposure to DEHP, higher concentrations of DEHP were found in the intestine, liver and spleen. Anatomical and histological analyses showed that the zebrafish spleen index was significantly increased and inflammatory damage was observed. Increased splenic neutrophil counts indicate inflammation and tissue damage. Transcriptomic filtering showed that 3579 genes were significantly altered. Metabolomic analysis detected 543 differential metabolites. Multi-omics annotation results indicated that arachidonic acid and 12-Hydroperoxyicosatetraenoic acid (HPETE) are involved in the key inflammatory pathway "Inflammatory mediator regulation of TRP channels". This study demonstrated the accumulation characteristics of DEHP in aquatic zebrafish and the mechanisms of inflammation and tissue damage in the spleen which involve endogenous arachidonic acid. This will provide theoretical basis and data support for health risk assessments and tissue damage of DEHP.

The active phthalate metabolite, DHEP, induces proliferation and metastasis of prostate cancer cells via upregulation of ß-catenin and downregulation of KLF7.

Phthalates such as DHEP are among the widely used compounds in industry. It has been shown that DHEP can convey various biological consequences in mammalian cells, among them, the carcinogenic effects of DHEP are emphasized. The present study aimed to assess the impact of DHEP exposure on the proliferation and invasiveness of DU145 prostate cancer cells through in vitro and in vivo models. The DU145 cells were treated with increasing concentrations of DHEP and the tumorigenic parameters were analyzed. KLF7 as a probable mediator of the effect of DHEP was either overexpressed or knocked down in DU145 to evaluate the probable impact of KLF7 on the biological effects of DHEP. The effect of DHEP was also studied in a DU145 xenograft tumor model. The moderate doses of DHEP increased the proliferation and migration of DU145 cells. In the case of gene expression patterns, DHEP reduced the levels of p53 and KLF7 while elevated the expression of ß-catenin. The knock-down of KLF7 conveyed comparable effects to that of DHEP to some degree and increased the proliferation of DU145 cells, while the transduction of KLF7 increased the expressions of p53 and p21 along with controlling the tumor size. The present study demonstrated the potential of DHEP in increasing the tumorigenic properties of DU145 cells along with a focus on the underlying mechanisms. Sustained exposure to DHEP can cause a dysregulation in balance between oncogenes and tumor suppressor genes which is the hallmark of malignant transformation. Thus, special considerations seem necessary for the safe exploitation of phthalates.

Association between phthalate exposure and obesity risk: A meta-analysis of observational studies.

According to epidemiological studies, phthalate exposure is associated with an increased risk of obesity in children and adults; however, these observations remain debatable. Therefore, we performed a systematic review and meta-analysis of the current literature to explore the effects of phthalate exposure on obesity. A systematic search was performed from inception to July 2022 in PubMed, EMBASE, Scopus, and Web of Science. Quality assessment was completed using criteria modified from Newcastle-Ottawa Scale (NOS) for the included studies. Meta-analysis showed that childhood exposure to MnBP, MBP, MEP, MiBP, and MECPP was positively correlated with obesity. In adults, MMP, MEP, and MiBP were positively correlated with adult abdominal obesity, while MEHHP, MECPP, and MCOP were positively correlated with adult general obesity. Subgroup analysis revealed that the positive correlation was particularly significant in women, as well as in Europe and the United States. Overall, a substantial association exists between phthalate exposure and obesity in children and adults. Sex and study site may provide limited sources of heterogeneity.

Bis(2-ethylhexyl) phthalate transfer from polyvinyl chloride sheet to several kinds of particles.

Bis(2-ethylhexyl) phthalate (DEHP) transfer from a polyvinyl chloride (PVC) sheet to 9 kinds of particles, namely, polyethylene particles (1-10, 45-53, 90-106 µm), soda lime glass particles (1-38, 45-53, 90-106 µm), black forest soil, carbon black, and cotton linter, for the particle weights of 0.3, 1, 3, and 12 mg/cm2, were determined for 1, 3, 7, and 14 days using a passive flux sampler (PFS), as well as standard dust. Transfer amounts to small polyethylene particles (1-10 µm), black forest soil, and carbon black were large (8.5, 16, and 48 µg/mg-particle, respectively, for 0.3 mg/cm2 for 14 days) and were similar to standard house dust (35 µg/mg-particle). On the other hand, transfer amount to large polyethylene particles (0.056-0.12 µg/mg-particle), soda lime glass (0.18-0.31 µg/mg-particle), and cotton linter (0.42-0.78 µg/mg-particle) were much lower. The DEHP transfer amount to the particles was proportional to the surface area of the particles, but not associated with the organic content. The DEHP transfer amount per surface area to small polyethylene particles was larger than that of other particles, suggesting the contribution of absorption into the polyethylene particle. However, for the larger polyethylene particles with different manufacturing process that may have different crystallinity, the contribution of absorption was small. The amount of DEHP transferred to soda lime glass did not differ from 1 to 14 days, suggesting that an adsorption equilibrium was reached after 1 day. The estimated value of particle/gas partition coefficients of DEHP, Kpg, of small polyethylene, black forest soil and carbon black were much higher (3.6, 7.1, and 18 m3/mg, respectively) than those of large polyethylene and soda lime glass particles (0.028-0.11 m3/mg).

Effects of cadmium and diethylhexyl phthalate on skin microbiota of Rana chinensis tadpoles.

Skin microbiotas play a crucial role in the health, homeostasis, and immune function of amphibians. The contaminants in water could affect the structure and composition of microbial communities. The effects of coexisting pollutants on frogs cannot be adequately explained by a single exposure due to the coexistence of Cd and DEHP in the environment. Following exposure to Cd and/or DEHP, we examined the histological characteristics of Rana chensinensis tadpoles. We also used the 16S rRNA gene sequencing technique to assess the relative abundance of skin microbial communities among tadpoles from each treatment group. Our findings indicate that R. chensinensis' skin experienced some degree of injury due to exposure to Cd and DEHP, which led to the imbalance of their skin microbial community homeostasis and thus interfered with the normal trial status of the host. That may eventually lead to the decline of the amphibian population.

DEHP mediates drug resistance by metabolic reprogramming in colorectal cancer cells.

Long-term exposure to diethylhexyl phthalate (DEHP), an endocrine-disrupting chemical (EDCs) and plasticizer widely used in consumer products, has been reported to be significantly positively correlated with increased risks of different human diseases, including various cancers, while the potential effect of DEHP on colorectal cancer progression was little studied. In the present study, we showed that DEHP could trigger the metabolic reprogramming of colorectal cancer cells, promote cell growth and decrease fluorouracil (5-FU) sensitivity. Mechanistic studies indicated that DEHP could reduce glycolysis activity and increase oxidative phosphorylation (OXPHOS) in SW620 cells. In addition, in vivo experiments showed that DEHP promoted tumorigenic progression and decreased survival time in mice. Collectively, our findings suggest that DEHP may be a potent risk factor for colorectal cancer development.

Induction of Caspase-dependent Apoptosis in Rat Bone Marrow Mesenchymal Stem Cells Due to Di-2-Ethylhexyl Phthalate Toxicity was Found to Arrest the Cell Cycle at the G1 Stage.

BACKGROUND: Di-(2-ethylhexyl) phthalate (DEHP) is used as a plasticizer in polyvinyl chloride products which is widely utilized. Previously we found, DEHP reduced the viability and proliferation ability of bone marrow mesenchymal stem cells (BMSCs). OBJECTIVE: In the present study, the mechanism of DEHP toxicity was investigated. METHODS: Rat BMSCs were cultured up to 3rd passage and their viability was determined after treatment with 100 and 500 µM of DEHP for 24 and 48 hours. The levels of sodium, potassium, and calcium as well as induction of apoptosis were investigated. Using flow cytometry, cell cycle analysis was performed and the expression of genes involved in the cell cycle was evaluated using reverse transcriptase-PCR. Data were analyzed and p < 0.05 was taken as the level of significance. RESULTS: Although the viability and electrolyte level of BMSCs were not affected with 100 µM of DEHP, this environmental pollution induced caspase-dependent apoptosis in a concentration-dependent manner. In both of the concentrations, DEHP arrests the cell cycle at the G0/G1 phase, and the expression of Cdk2 and Cdk4 was significantly reduced whereas an over-expression of P53 was observed. However, the expression of the raf1 gene remained unchanged. CONCLUSION: DEHP induces caspase-dependent apoptosis in BMSCs and arrests the cell cycle due to the reduction of Cdk2 and Cdk4 expression via over-expression of P53.

[Diethylhexyl phthalate induces anxiety-like behavior and learning and memory impairment in mice probably by damaging blood-brain barrier].

OBJECTIVE: To investigate the effects of diethylhexyl phthalate (DEHP) exposure on anxiety-like behaviors and learning and memory ability in mice and explore the underlying mechanism. METHODS: Forty male ICR mice were randomized equally into control group (0 mg/kg) and 10, 50 and 100 mg/kg DEHP exposure groups, in which the mice were exposed to DEHP at the indicated doses by gavage for 4 weeks. After the treatments, the mice were assessed for behavioral changes using open filed test, elevated plus-maze and Morris water maze test. Brain tissues were collected from the mice for determination of malondialdehyde (MDA) content, pathologies and expressions of ZO-1 and occludin in the hippocampus. RESULTS: Compared with the control group, the mice with DEHP exposure for 4 weeks exhibited no significant body weight change (P>0.05) but presented with obvious behavioral changes, manifested by reduced movement distance (P < 0.05) and time spent in the center of the open field (P < 0.05), reduced movement distance (P < 0.05) and time spent in the open arm of the elevated maze (P < 0.05), significantly increased latency of searching for the platform (P < 0.05), and decreased frequency of crossing the platform (P < 0.05). HE staining showed obvious vertebral cell death in the hippocampal CA1 to CA3 regions of the mice with DEHP exposure. The exposed mice showed significantly increased MDA content and decreased expressions of ZO-1 and occludin at both the mRNA and protein levels in the hippocampus (P < 0.05 or 0.01). Multivariate linear regression analysis suggested a close correlation between anxiety-like behaviors and learning and memory abilities in DEHP-exposed mice. CONCLUSION: DEHP exposure may cause damages of the blood-brain barrier and the pyramidal cells in the hippocampus of mice, thereby inducing anxiety-like behaviors and learning and memory impairment.

Microorganisms in the reproductive system and probiotic's regulatory effects on reproductive health.

The presence of microbial communities in the reproductive tract has been revealed, and this resident microbiota is involved in the maintenance of health. Intentional modulation via probiotics has been proposed as a possible strategy to enhance reproductive health and reduce the risk of diseases. The male seminal microbiota has been suggested as an important factor that influences a couple's health, pregnancy outcomes, and offspring health. Probiotics have been reported to play a role in male fertility and to affect the health of mothers and offspring. While the female reproductive microbiota is more complicated and has been identified in both the upper and lower reproductive systems, they together contribute to health maintenance. Probiotics have shown regulatory effects on the female reproductive tract, thereby contributing to homeostasis of the tract and influencing the health of offspring. Further, through transmission of bacteria or through other indirect mechanisms, the parent's reproductive microbiota and probiotic intervention influence infant gut colonization and immunity development, with potential health consequences. In vitro and in vivo studies have explored the mechanisms underlying the benefits of probiotic administration and intervention, and an array of positive results, such as modulation of microbiota composition, regulation of metabolism, promotion of the epithelial barrier, and improvement of immune function, have been observed. Herein, we review the state of the art in reproductive system microbiota and its role in health and reproduction, as well as the beneficial effects of probiotics on reproductive health and their contributions to the prevention of associated diseases.

Associating diethylhexyl phthalate to gestational diabetes mellitus via adverse outcome pathways using a network-based approach.

Gestational diabetes mellitus (GDM) is a common pregnancy complication that is harmful to both the woman and fetus. Several epidemiological studies have found that exposure to diethylhexyl phthalate (DEHP), an endocrine disruptor ubiquitous in the environment, may be associated with GDM. This study aims to investigate the mechanism between DEHP and GDM using the adverse outcome pathway (AOP) framework, which can integrate information from different sources to elucidate the causal pathways between chemicals and adverse outcomes. We applied a network-based workflow to integrate diverse information to generate computational AOPs and accelerate the AOP development. The interactions among DEHP, genes, phenotypes, and GDM were retrieved from several publicly available databases, including the Comparative Toxicogenomics Database (CTD), Computational Toxicology (CompTox) Chemicals Dashboard, DisGeNET, MalaCards, Gene Ontology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG). Based on the above interactions, a DEHP-Gene-Phenotype-GDM network consisting of 52 nodes and 227 edges was formed to support AOP construction. The filtered genes and phenotypes were assembled as molecular initiating events (MIEs) and key events (KEs) according to the upstream and downstream relationships, generating a computational AOP (cAOP) network. Based on the Organization for Economic Co-operation and Development handbook of AOPs, a cAOP was assessed and applied to determine the effects of DEHP on GDM. DEHP could increase TNF-α, downregulate the glucose uptake process, and lead to GDM. Overall, this study revealed the utility of computational methods in integrating a variety of datasets, supporting AOP development, and facilitating a better understanding of the underlying mechanism of exposure to chemicals on human health.

Impacts of diethylhexyl phthalate and overfeeding on physical fitness and lipid mobilization in Danio rerio (zebrafish).

As the prevalence of obesity has steadily increased on a global scale, research has shifted to explore potential contributors to this pandemic beyond overeating and lack of exercise. Environmental chemical contaminants, known as obesogens, alter metabolic processes and exacerbate the obese phenotype. Diethylhexyl phthalate (DEHP) is a common chemical plasticizer found in medical supplies, food packaging, and polyvinyl materials, and has been identified as a probable obesogen. This study investigated the hypothesis that co-exposure to DEHP and overfeeding would result in decreased lipid mobilization and physical fitness in Danio rerio (zebrafish). Four treatment groups were randomly assigned: Regular Fed (control, 10 mg/fish/day with 0 mg/kg DEHP), Overfed (20 mg/fish/day with 0 mg/kg DEHP), Regular Fed + DEHP (10 mg/fish/day with 3 mg/kg DEHP), Overfed + DEHP (20 mg/fish/day with 3 mg/kg DEHP). After 24 weeks, swim tunnel assays were conducted on half of the zebrafish from each treatment to measure critical swimming speeds (Ucrit); the other fish were euthanized without swimming. Body mass index (BMI) was measured, and tissues were collected for blood lipid characterization and gene expression analyses. Co-exposure to DEHP and overfeeding decreased swim performance as measured by Ucrit. While no differences in blood lipids were observed with DEHP exposure, differential expression of genes related to lipid metabolism and utilization in the gastrointestinal and liver tissue suggests alterations in metabolism and lipid packaging, which may impact utilization and ability to mobilize lipid reserves during physical activity following chronic exposures.

Association of phthalate exposure with autistic traits in children.

BACKGROUND: Phthalates are synthetic chemicals with endocrine-disrupting properties. They are reportedly associated with various neurotoxic outcomes. Studies on exposure to phthalates and children's autistic traits have shown inconsistent results with respect to sex and susceptible time periods. We investigated the association of phthalate exposure during the prenatal period and childhood with autistic traits over time using a birth cohort in South Korea. METHODS: Five phthalate metabolites were measured during mid-term pregnancy and children's follow-up at ages of 4, 6, and 8 years among a total of 547 mother-child pairs. The social communication questionnaire (SCQ) was used to assess autistic traits of children at each time point. The relationship between phthalate metabolites and SCQ scores were analyzed by exposure windows and sex. RESULTS: A 2.7 fold increase in di-(2-ethylhexyl) phthalate metabolite levels, mono-(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) and mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP) during pregnancy was associated with increased SCQ scores at 4 years by 8.5% (95% confidence intervals [CI]: 1.9%, 15.5%) and 7.4% (95% CI: 0.3%, 15.0%), respectively, but not at the age of 6 or 8 years. Moreover, MEHHP levels at ages of 4 and 8 years were associated with increased SCQ scores at 8 years by 9.9% (95% CI: 1.8%, 18.6%) and 9.6% (95% CI: 1.3%, 18.6%), respectively. Boys showed stronger associations between phthalate exposure and SCQ scores than girls. CONCLUSION: The study suggested different susceptible time windows of phthalate exposure: exposure during pregnancy is associated with autistic traits in young children, whereas exposure during early childhood years leads to autistic traits in school-aged children, particularly boys.

[Influence of Different Soil Conditioner on the Transfer and Transformation of Cadmium and Phthalate Esters in Soil].

This study examines the existing common form of soil pollution, combined organic and inorganic pollution. Cadmium (Cd) is the most important inorganic element in soil pollution. Due to the widespread use of plastic film, phthalates have become the main organic pollutants in soil. Pot experiments were conducted with purple soil from southwest China, and Chinese cabbage was used as a biological indicator. Different concentration gradients of Cd and diethylhexyl phthalate (DEHP) was used as foreign pollutants. The soil was treated with one of the six common soil conditioners, namely potassium feldspar powder, oyster shell powder, biological carbon powder (biochar), calcium, potassium carbonate, and calcium phosphate, to examine the effect of conditioners on cadmium morphology, DEHP content in contaminated soil, and cadmium and DEHP absorption in Chinese cabbage. The results showed that biochar is the optimal soil conditioner for the remediation of cadmium-phthalate composite pollution in purple soil. Subsequently, the effects of soil biochar content on cadmium pollution and phthalate ester migration were studied. Uncontaminated control soil, Cd-contaminated soil, and DEHP-contaminated soil were examined by pot experiments, and biochar treatments with mass fraction of 0%, 0.5%, 1%, 3%, and 5% added to cadmium contaminated soil were used to determine its influence on Cd morphology and DEHP content of contaminated soil.

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

Diethylhexyl phthalate (DEHP) is one of the most important derivatives of phthalate that has devastating effects on nervous system function. In this study, the effects of exposure with low doses of DEHP during pregnancy and lactation periods have been evaluated in rat's puppies. DEHP at doses 5, 40, 400 µg/kg/day and 300 mg/kg/day was given to mothers by gavage during pregnancy and lactation. The spatial and working memories were evaluated by Morris water maze test and Y maze, respectively. Oxidative stress levels were measured by biochemical tests. Histopathology of hippocampal tissue was assessed using hematoxylin and eosin, Nissl staining, and immunohistofluorescence in 60-days-old puppies. Behavioral data showed that low doses of DEHP decreased the working and spatial memories of male rats. Increased oxidative stress and decreased antioxidant activity were also observed in the hippocampus of rats which received the low doses of DEHP. However, neuronal damage, inflammation, and astrocyte activation were not significantly increased in the hippocampus of rats. Overall, exposure of mothers to low doses of DEHP during pregnancy and lactation cause behavioral deficits, especially in male newborn. The destructive effects of low doses of DEHP might be mediated through increased levels of oxidative stress in the brain.

DEHP Down-Regulates Tshr Gene Expression in Rat Thyroid Tissues and FRTL-5 Rat Thyrocytes: A Potential Mechanism of Thyroid Disruption.

BACKGROUND: Di-2-ethylhexyl phthalate (DEHP) is known to disrupt thyroid hormonal status. However, the underlying molecular mechanism of this disruption is unclear. Therefore, we investigated the direct effects of DEHP on the thyroid gland. METHODS: DEHP (vehicle, 50 mg/kg, and 500 mg/kg) was administered to Sprague-Dawley rats for 2 weeks. The expression of the thyroid hormone synthesis pathway in rat thyroid tissues was analyzed through RNA sequencing analysis, quantitative reverse transcription-polymerase chain reaction (RT-PCR), and immunohistochemical (IHC) staining. DEHP was treated to FRTL-5 rat thyroid cells, and an RT-PCR analysis was performed. A reporter gene assay containing the promoter of thyroid stimulating hormone receptor (TSHR) in Nthy-ori 3-1 human thyroid cells was constructed, and luciferase activity was determined. RESULTS: After DEHP treatment, the free thyroxine (T4) and total T4 levels in rats significantly decreased. RNA sequencing analysis of rat thyroid tissues showed little difference between vehicle and DEHP groups. In the RT-PCR analysis, Tshr expression was significantly lower in both DEHP groups (50 and 500 mg/kg) compared to that in the vehicle group, and IHC staining showed that TSHR expression in the 50 mg/kg DEHP group significantly decreased. DEHP treatment to FRTL-5 cells significantly down-regulated Tshr expression. DEHP treatment also reduced luciferase activity in a reporter gene assay for TSHR. CONCLUSION: Although overall genetic changes in the thyroid hormone synthesis pathway are not clear, DEHP exposure could significantly down-regulate Tshr expression in thyroid glands. Down-regulation of Tshr gene appears to be one of potential mechanisms of thyroid disruption by DEHP exposure.

Mixed plasticizers aggravated apoptosis by NOD2-RIP2-NF-κB pathway in grass carp hepatocytes.

The wide application of plastics led to the wide exposure of plasticizers to the environment. As a new environmental pollutant, plasticizers' toxicity researches were far from enough in fish. To further explore these mechanisms, we used two common plasticizers (Diethylhexyl phthalate (DEHP) and dibutyl phthalate (DBP) expose to grass carp hepatocytes (L8824). The results showed that the mRNA levels of NOD2-RIP2-NF-κB signal pathway and its downstream inflammatory genes were significantly increased compared to those in control group. Then, the levels of mRNAs and proteins of apoptosis markers were changed, and hepatocytes apoptosis was induced. After DBP and DEHP exposure together, there were higher levels of inflammatory factors and the proportion of apoptotic cells. After NOD2 inhibitor treatment, the phenomena mentioned above were obviously alleviated. We conclude that DBP and DEHP exposure at least partially activated the NOD2-RIP2-NF-κB signal pathway in grass carp hepatocytes, and caused inflammation and apoptosis. In terms of hepatotoxicity, there was synergistic relationship between DBP and DEHP. In addition, we put forward new views on the use of plasticizers: select low toxicity plasticizers, then reduce the types of plasticizers used and reduce the high toxicity level of mixed plasticizers.