Perinatal exposure to nonylphenol impairs dendritic outgrowth of cerebellar Purkinje cells in progeny

Prenatal exposure to corn oil, CMC-Na or DMSO affects physical development and multi-organ functions in fetal mice

Corn oil, sodium carboxymethyl cellulose (CMC-Na), and dimethyl sulfoxide (DMSO) are widely used as solvents or suspensions in animal experiments, but the effects of prenatal exposure to them on fetal development have not been reported. In this study, Kunming mice were given a conventional dose of corn oil (9.2g/kg·d), CMC-Na (0.05g/kg·d) or DMSO (0.088g/kg·d) during gestation days 10-18, and the pregnancy outcome, fetal physical development, serum phenotype, and multi-organ function changes were observed. The results showed that corn oil decreased serum triglyceride level in males but increased their serum testosterone and CORT levels, and affected female placenta and female/male multi-organ functions (mainly bone, liver, kidney). CMC-Na increased female/male body lengths and tail lengths, decreased serum glucose and total cholesterol levels in males as well as increased their serum LDL-C/HDL-C ratio and testosterone level, decreased female serum bile acid level, and affected male/female placenta and multi-organ functions (mainly bone, liver, hippocampus). DMSO decreased male body weight and serum glucose level, decreased male/female serum bile acid levels, and affected male/female placenta and multi-organs functions (mainly bone, hippocampus, adrenal gland). In conclusion, prenatal exposure to a conventional dose of corn oil, CMC-Na or DMSO could affect fetal physical development and multi-organ functions, and has the characteristics of "multi-pathway, multi-organ and multi-target". This study provides the experimental basis for the rational selection of solvents or suspensions in pharmacology and toxicology studies. DATA AVAILABILITY: Data will be made available on request.

Developmental exposure to chlorpyrifos causes neuroinflammation via necroptosis in mouse hippocampus and human microglial cell line

Neurodevelopmental exposure to chlorpyrifos (CPF) could increase risks for neurological disorders, such as autism spectrum disorder, cognitive impairment, or attention deficit hyperactivity disorder. The potential involvement of microglia reactive to inflammatory stimuli in these neurological disorders has been generally reported. However, the concrete effects and potential mechanisms of microglia dysfunction triggered by developmental CPF exposure remain unclear. Therefore, we established mouse and human embryonic microglial cells (HMC3 cell) models of developmental CPF exposure to evaluate the effects of developmental CPF exposure on neuroinflammation and underlying mechanisms. The results showed that developmental exposure to CPF enhanced the expression of Iba1 in hippocampus. CPF treatment increased inflammatory cytokines levels and TSPO expression in hippocampus and HMC3 cells. The levels of necroptosis and necroptosis-related signaling RIPK/MLKL were increased in hippocampus and HMC3 cells following CPF exposure. Furthermore, the expression of TLR4/TRIF signaling was increased in hippocampus and HMC3 cells subjected to CPF exposure. Notably, the increased levels of TLR4/TRIF signaling, RIPK/MLKL signaling, necroptosis and pro-inflammatory cytokines induced by CPF treatment were remarkably inhibited by TAK-242 (a specific TLR4 inhibitor). Additionally, the necroptosis and pro-inflammatory cytokines production induced by CPF treatment were significantly relieved by Nec-1 (a specific RIPK1 inhibitor). In general, the above results suggested that activated microglia in hippocampus subjected to developmental CPF exposure underwent RIPK1/MLKL-mediated necroptosis regulated by TLR4/TRIF signaling.

Relationship between exposure of alkylphenols in serum of pregnant women during early pregnancy and adverse birth outcomes

Alkylphenols are a type of endocrine disruptors, which are commonly found in personal care products, food, and water and are more harmful to the human body. To investigate the relationship between exposure of alkylphenols in serum of pregnant women during early pregnancy and adverse birth outcomes, a total of 2035 healthy pregnant women and their neonates were recruited in the birth cohort of Zhuang nationality in Guangxi from 2015 to 2018. The peripheral venous blood samples were collected from pregnant women in early pregnancy; the concentrations of nonylphenol (NP), 4-nonylphenol (4-N-NP), 4-tert-octylphenol (4-T-OP), and 4-n-octylphenol (4-N-OP) in serum were detected by ultra-performance liquid performance chromatography-tandem mass spectrometry (UPLC-MS). Binary logistic regression showed that NP [OR = 1.40 (95% CI: 1.00, 1.94)] was positively associated with preterm birth. Restricted cubic spline analyses showed that logNP and log4-T-OP had non-linearity associations with preterm birth (logNP: P_overall = 0.006, P_non-linear = 0.003; log4-T-OP: P_overall = 0.004, P_non-linear = 0.002). Multiple linear regression analysis showed that maternal serum concentration of NP was negatively associated with birth weight of perinatal infants (β = -14.68, 95% CI: -29.18, -0.19), which may be sensitive in male neonates (β = -26.18, 95% CI: -47.33, -5.02). The findings demonstrate that nonylphenol is a risk factor of preterm birth, and nonylphenol is negatively associated with the birth weight in male infants.

Behavioral disorders caused by nonylphenol and strategies for protection

Nonylphenol (NP) is widely used in daily production and life due to its good emulsification. In this review, we discuss toxicology studies that examined behavioral disorders caused by NP, the corresponding toxicological mechanisms in the central nervous system (CNS), and strategies for protection. Available in vitro and in vivo evidence suggests that exposure to NP during adulthood or early childhood is associated with cognitive dysfunction, including depression-like behaviors, anxiety-like behaviors, and impaired learning and memory. The main mechanisms underlying NP-related cognitive disorders include inflammation, destruction of synaptic plasticity, and destruction of important signaling pathways that affect the synthesis and secretion of neurotransmitters. The effects and mechanisms of NP exposure on CNS-mediated reproductive function, including interference with the expression of hormones, proteins, and enzymes, are discussed. Other abnormal behaviors such as locomotor activity and swimming behavior are also described. Several measures to prevent NP neurotoxicity are summarized. These measures are based on the toxicological mechanisms underlying NP exposure and include external protection and internal self-regulation of the nervous system. Finally, a new treatment idea is proposed based on the gut-brain axis. Characterizing the behavioral changes and underlying toxicity mechanisms associated with NP exposure and investigating the possible methods of treatment will help to expand the understanding of these mechanisms and could lead to more effective treatments.

Perinatal exposure to nonylphenol promotes proliferation of granule cell precursors in offspring cerebellum: Involvement of the activation of Notch2 signaling

Nonylphenol (NP), a widely diffused persistent organic pollutant (POP), has been shown to impair cerebellar development and cause cerebellum-dependent behavioral and motor deficits. The precise proliferation of granule cell precursors (GCPs), the source of granular cells (GCs), is required for normal development of cerebellum. Thus, we established an animal model of perinatal exposure to NP, investigated the effect of NP exposure on the cerebellar GCPs proliferation, and explored the potential mechanism involved. Our results showed that perinatal exposure to NP increased cerebellar weight, area, and internal granular cell layer (IGL) thickness in offspring rats. Perinatal exposure to NP also resulted in the GCPs hyperproliferation in the external granular layer (EGL) of the developing cerebellum, which may underlie the above-mentioned cerebellar alterations. However, our results suggested that perinatal exposure to NP had no effects on the length of GCPs proliferation. Meanwhile, perinatal exposure to NP also increased the activation of Notch2 signaling, the regulator of GCPs proliferation. In conclusion, our results supported the idea that exposure to NP caused the hyperproliferation of GCPs in the developing cerebellum. Furthermore, our study also provided the evidence that the activation of Notch2 signaling may be involved in the GCPs hyperproliferation.

Perinatal exposure to nonylphenol delayed myelination in offspring cerebellum

As a stable environmental contaminant, nonylphenol (NP) has been shown to induce some neurological deficits in the cerebellum, although the underlying mechanism is still unknown. In the present study, we aimed to investigate the effects of perinatal exposure to NP on myelination, an important process essential for the intact cerebellar function, in the offspring cerebellum. Exposure to NP delayed the myelination in the offspring cerebellum during perinatal period. The myelination recovered in the cerebellum of offspring exposed to NP over time, and returned to normal in adulthood. In addition, perinatal exposure to NP reduced mature oligodendrocytes (myelin-forming glial cells) and increased astrocytes in the offspring cerebellum. BMP signaling is believed to negatively regulate oligodendrogliogenesis and myelination. In the present study, BMP4, p-Smad1/5, and ID4, key members of BMP signaling, were increased in the cerebellum of offspring exposed to NP. Taken together, these lines of evidence suggest that the activation of BMP signaling may underlie the decreased oligodendrogliogenesis and increased astrogliogenesis, and the consequent delay of myelination in the cerebellum of offspring perinatally exposed to NP.

Dynamic monitoring of depressive behavior induced by nonylphenol and its effect on synaptic plasticity in rats

The etiology of depression is not known, it is thought that endocrine-disrupting chemicals (EDCs) contribute to the disease. Results of our previous research have shown that nonylphenol (NP), a well-known EDC, has neurotoxic effects, however, whether NP can induce depressive behavior by affecting synaptic plasticity has not yet been clearly elucidated. The depressive behavior induced by subchronic exposure to NP and its effect on the neuronal synaptic plasticity in rats are dynamically observed. Thirty Sprague-Dawley rats were randomly divided into 3 groups: control group (C, corn oil), NP group (NP, 4 mg/kg), and depression model group (D, corticosterone 20 mg/kg). There were 8 rats in each group. The depressive behavior of rats was tested by sucrose preference test, open-field test, and forced swimming test once a month for 3 months. The serum levels of brain-derived neurotrophic factor (BDNF) and corticosterone were detected by ELISA assay, and cellular morphological changes were observed by hematoxylin-eosin (HE) staining. The number of nerve cells, the length of dendrites, and the density of dendritic spines were observed by Golgi staining, and the synaptic cleft width, the postsynaptic density (PSD) thickness, and the synaptic interface curvature were observed by transmission electron microscope. Compared with the control group, the consumption of sucrose solution decreased in the NP group at the 2nd and 3rd month compared to the 1st month (F = 9.887, P = 0.002). The number of central square entries, the central square duration, and the total distance of movement were all decreased, and the decreasing degrees at the 3rd month were greater than those at the 1st month (F = 21.191, P < 0.001; F = 9.836, P = 0.002). The time of immobility for the NP group at the 1st month was higher than that in the control group (F = 6.912, P = 0.002). The expression of BDNF in the NP-treated group was higher than the control, while the expression of corticosterone in the NP-treated group was lower than the control. In the NP group, the cytoplasm of nerve cells contracted and appeared disordered. The neuron arrangement was disordered, and the number of cells, the length of the apex, the length of the basal dendrites, and the dendritic spine density were all lower in the NP group than those in the control group. The PSD thickness, the synaptic cleft width, and synaptic interface curvatures were all decreased in the NP group when compared to the control group. Subchronic exposure to 4 mg/kg NP led to depressive behavior in rats, and the depressive behavior and alterations in synaptic plasticity were more obvious with longer exposure time.