Female mice prenatally exposed to valproic acid exhibit complex and prolonged social behavior deficits

Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder characterized mainly by deficits in social communication and stereotyped and restricted behavior and interests with a male to female bias of 4.2/1. Social behavior in ASD animal models is commonly analyzed in males, and seldomly in females, using the widely implemented three-chambers test procedure. Here, we implemented a novel procedure, the Live Mouse Tracker (LMT), combining artificial intelligence, machine learning procedures and behavioral measures. We used it on mice that were prenatally exposed to valproic acid (VPA) (450 mg/kg) at embryonic day 12.5, a widely recognized and potent ASD model that we had previously extensively characterized. We focused on female mice offspring, in which social deficits have been rarely documented when using the 3-CT procedure. We recorded several parameters related to social behavior in these mice, continuously for three days in groups of four female mice. Comparisons were made on groups of 4 female mice with the same treatment (4 saline or 4 VPA) or with different treatments (3 saline and 1 VPA). We report that VPA females show several types of social deficits, which are different in nature and magnitude in relation with time. When VPA mice were placed in the LMT alongside saline mice, their social deficits showed significant improvement as early as 1 h from the start of the experiment, lasting up to 3 days throughout the duration of the experiment. Our findings suggest that ASD may be underdiagnosed in females. They also imply that ASD-related social deficits can be ameliorated by the presence of typical individuals.

Sex-dependent alterations of inflammatory factors, oxidative stress, and histopathology of the brain-gut axis in a VPA-induced autistic-like model of rats

INTRODUCTION

In this study, we aimed to investigate the inflammatory factors, oxidative stress, and histopathological consequences of the brain-gut axis in male and female rats prenatally exposed to VPA.

METHODS

Pregnant Wistar rats were randomly divided into two groups. The animals received saline, and valproic acid (VPA) (600 mg/kg, i.p.) on embryonic day 12.5 (E12.5). All offspring were weaned on postnatal day 21, and the experiments were done in male and female rats on day 60. The brain and intestine tissues were extracted to assess histopathology, inflammation, and oxidative stress.

RESULTS

An increase of interleukin-1β (IL-1β) and interleukin-6 (IL-6) and a decrease of interleukin-10 (IL-10) were observed in the two sexes and two tissues of the autistic rats. In the VPA-exposed animals, malondialdehyde (MDA) and protein carbonyl (PC) increased in the brain of both sexes and the intestines of only the males. The total antioxidant capacity (TAC), superoxide dismutase (SOD), and catalase (CAT) significantly decreased in both tissues of male and female autistic groups. Histopathological evaluation showed that the %apoptosis of the cortex in the autistic male and female groups was more than in controls whereas this parameter in the CA1 and CA3 was significant only in the male rats. In the intestine, histopathologic changes were seen only in the male autistic animals.

CONCLUSION

The inflammatory and antioxidant factors were in line in the brain-gut axis in male and female rats prenatally exposed to VPA. Histopathological consequences were more significant in the VPA-exposed male animals.

Vitamin A ameliorates valproic acid-induced autism-like symptoms in developing zebrafish larvae by attenuating oxidative stress and apoptosis

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by social deficits and repetitive/stereotyped behaviors. Prenatal exposure to valproic acid (VPA) has been reported to induce ASD-like symptoms in human and rodents. However, the etiology and pathogenesis of ASD have not been well elucidated. This study aimed to explore the mechanisms underlying VPA-induced ASD-like behaviors using zebrafish model and investigated whether vitamin A could prevent VPA-induced neurotoxicity. Here, zebrafish embryos were exposed to 0, 25 and 50 μM VPA from 4 to 96 h post fertilization (hpf) and the neurotoxicity was assessed. Our results showed that VPA affected the normal development of zebrafish larvae and induced ASD-like behaviors, including reduced locomotor activity, decreased distance near conspecifics, impaired social interaction and repetitive swimming behaviors. Exposure to VPA decreased the GFP signal in transgenic HuC:egfp zebrafish according to the negative effect of VPA on the expression of neurodevelopmental genes. In addition, VPA enhanced oxidative stress by promoting the production of reactive oxygen species (ROS) and hydrogen peroxide (H2O2) and inhibiting the activity of superoxide dismutase, then triggered apoptosis by upregulation of apoptotic genes. These adverse outcomes were mitigated by vitamin A, suggesting that vitamin A rescued VPA-induced ASD-like symptoms by inhibiting oxidative stress and apoptosis. Overall, this study identified vitamin A as a promising strategy for future therapeutic regulator of VPA-induced ASD-like behaviors.

Effect of valproic acid on the formation and migration of cranial neural crest cells at the early developmental stages in rat embryos

Cranial neural crest cells (NCCs) are critical for craniofacial development. The administration of valproic acid (VPA) to pregnant females causes craniofacial malformations in offspring. However, the in vivo influence of VPA on mammalian cranial NCCs remains unclear. In this study, we aimed to elucidate the developmental stage-specific effect of VPA on cranial NCCs through the administration of a single dose of VPA to pregnant rat females immediately prior to the formation of the cranial neural crest (NC). We performed whole-mount immunohistochemistry or in situ hybridization to examine localization changes of gene transcripts associated with the epithelial-mesenchymal transition of the cranial NC (i.e., cranial NCC formation) and cranial NCC migration. The results showed that Hoxa2 mRNA was abnormally detected and Sox9 mRNA expression was decreased in the midbrain-rhombomere (R) 1/2 NC, which forms cranial NCCs that migrate to the frontonasal mass (FNM) and branchial arch (BA) 1, through VPA administration, thus reducing the formation of SNAI2-positive NCCs. Hoxa2-positive NCCs were detected normally in BA2 and abnormally in FNM and BA1, which are normally Hox-free, implying VPA-induced abnormal cranial NCC migration. In vitro verification experiments using the whole embryo culture system revealed that midbrain-R4 NCC migration was abnormal. These results indicate that VPA reduces the formation/delamination of the midbrain-R1/2 NCCs in a developmental stage-specific manner and subsequently causes the abnormal migration of R4 NCCs, which suggests that the abnormal formation and migration of cranial NCCs contribute to the inhibition of axonal elongation in the trigeminal nerve and a reduction in head size.

Investigating the effects of valproic acid on placental epigenetic modifications and development in the CD-1 mouse model

Gestational exposure to the anticonvulsant drug valproic acid (VPA) is associated with congenital malformations and neurodevelopmental disorders through its action as a histone deacetylase inhibitor. VPA can elicit placental toxicity and affect placental growth and development. The objective of this study was to evaluate the impact of maternal exposure to VPA on the mouse placenta following exposure on gestational day (GD) 13 since previous studies have shown that mice exposed at this time during gestation give birth to offspring with an autism spectrum disorder-like phenotype. We exposed CD-1 dams to a teratogenic dose (600 mg/kg) of VPA or saline on GD13 and assessed fetoplacental growth and development on GD18. We evaluated epigenetic modifications, including acetylated histone H4 (H4ac), methylated H3K4 (H3K4me2) using immunohistochemistry, and global DNA methylation in the placenta at 1, 3, and 24 h following maternal exposure on GD13. In utero exposure to VPA on GD13 significantly decreased placental weight and increased fetal resorptions. Moreover, VPA significantly increased the staining intensity of histone H4 acetylation and H3K4 di-methylation across the placenta at 1 and 3 h post maternal dose. Our results also demonstrate that VPA significantly decreased global DNA methylation levels in placental tissue. These results show that gestational exposure to VPA interferes with placental growth and elicits epigenetic modifications, which may play a vital role in VPA-induced developmental toxicity.

Aggravation of cognitive impairments in the valproic acid-induced animal model of autism in BALB/c mice infected with Toxoplasma gondii

PURPOSE

Toxoplasmosis is a disease caused by infection with a type of coccidial protozoan parasite called Toxoplasma gondii. The relationship between toxoplasmosis and cognitive disorders in neurodegenerative diseases has been proven. There is also evidence that children born to Toxoplasma-infected mothers are more likely to develop autism.

METHODS

In the present study, Toxoplasma-infected pregnant BALB/c mice were given valproic acid to induce autism in their male offspring, and their social behaviors, learning, and memory were examined. Chronic toxoplasmosis was established in BALB/c mice by intraperitoneal injection of cyst form of T. gondii. To induce autism, 600 mg/kg of valproic acid was injected intraperitoneally into mice on the 12.5th day of pregnancy. The behavioral experiments, such as social interaction, novel object recognition, and passive avoidance tasks, were performed on male offspring at 50 days.

RESULTS

Toxoplasma and valproic acid during the embryonic period caused social communication deficits and disrupted recognition memory and avoidance memory in offspring. Our findings showed that administering valproic acid to Toxoplasma-infected mothers exacerbates cognitive disorders in their offspring.

Pharmacokinetic characterisation of a valproate Autism Spectrum Disorder rat model in a context of co-exposure to α-Hexabromocyclododecane

Assessing the role of α-hexabromocyclododecane α-HBCDD as a factor of susceptibility for Autism Spectrum disorders by using valproic acid-exposed rat model (VPA) required characterizing VPA pharmacokinetic in the context of α-HBCDD-co-exposure in non-pregnant and pregnant rats. The animals were exposed to α-HBCDD by gavage (100 ng/kg/day) for 12 days. This was followed by a single intraperitoneal dose of VPA (500 mg/kg) or a daily oral dose of VPA (500 mg/kg) for 3 days. Exposure to α-HBCDD did not affect the pharmacokinetics of VPA in pregnant or non-pregnant rats. Surprisingly, VPA administration altered the pharmacokinetics of α-HBCDD. VPA also triggered higher foetal toxicity and lethality with the PO than IP route. α-HBCDD did not aggravate the embryotoxicity observed with VPA, regardless of the route of exposure. Based on this evidence, a single administration of 500 mg/kg IP is the most suitable VPA model to investigate α-HBCDD co-exposure.

Valproic acid elevates HIF-1α-mediated CGB expression and suppresses glucose uptake in BeWo cells

Placental dysfunction can disrupt pregnancy. However, few studies have assessed the effects of chemical-induced toxicity on placental function. Here, we examined the effects of valproic acid (VPA) as a model chemical on production of hormones and on glucose uptake in human choriocarcinoma cell line BeWo. Cells were treated with forskolin to differentiate into syncytiotrophoblasts, which were then treated with VPA for 72 hr. Real-time RT-PCR analysis showed that VPA significantly increased the mRNA expression of chorionic gonadotropin β (CGB), a hormone that is produced by the placenta in the first trimester of pregnancy, relative to that in the forskolin-only group. It also suppressed the increase in intracellular glucose uptake and GLUT1 level observed in the forskolin-only group. RNA-seq analysis and pathway database analysis revealed that VPA consistently decreased the level of HIF-1α protein and expression of its downstream target genes HK2 and ADM in the hypoxia pathway. Cobalt chloride, a HIF-1α inducer, inhibited CGB upregulation in VPA-treated cells and rescued VPA-induced suppression of glucose uptake and GLUT1 level. Thus, HIF-1α-mediated elevation of CGB expression and suppression of glucose uptake by VPA is a novel mechanism of placental dysfunction.

Transcriptome Analysis and Epigenetics Regulation in the Hippocampus and the Prefrontal Cortex of VPA-Induced Rat Model

Autism spectrum disorders (ASD) are a highly heterogeneous group of neurodevelopmental disorders caused by complex interaction between various genes and environmental factors. As the hippocampus and prefrontal cortex are involved in social recognition, they are the regions of the brain implicated in autism. The effects of prenatal exposure to valproic acid (VPA) can induce an ASD phenotype in both humans and rats; this tool is commonly used to model the complexity of ASD symptoms in the laboratory. However, researchers rarely undertake epigenetic regulation of the brain regions using this model. The present study has addressed this gap by examining gene expression abnormalities in the hippocampus and prefrontal cortex in the VPA rat model of ASD. mRNA and miRNA sequencing was performed on samples from the hippocampus and prefrontal cortex of the VPA model of autism. According to the analysis, 3000 mRNAs in the hippocampus and 2187 mRNAs in the prefrontal cortex showed a significant difference in expression between the VPA and saline groups. In addition, there were 115 DE miRNAs in the hippocampus and 14 DE miRNAs in the prefrontal cortex. Further, the predicted and validated target mRNA of DE miRNA enriched pathways involved neurotransmitter uptake, long-term synaptic depression, and AMPA receptor complex (anti-GluA2-b) in the hippocampus; as well as the neuroactive ligand-receptor interaction and regulation of postsynaptic membrane potential in the prefrontal cortex. This revealed the negative regulation network of miRNAs-mRNAs in the hippocampus and prefrontal cortex, while filtering out key genes (miR-10a-5p and Grm3). Finally, the significant variable miR-10a-5p and its negative regulated genes (Grm3) were verified in both brain regions by QPCR. Importantly, the fact that miR-10a-5p downregulated Grm3 in both the hippocampus and the prefrontal cortex may play a potentially significant role in the occurrence and development of autism. This study suggests that the VPA model has the potential to reproduce ASD-related hippocampus and prefrontal cortex abnormalities, at the epigenetic and transcriptional levels. Furthermore, the network of miRNAs-mRNAs was confirmed; this negative regulatory relationship may play a key role in determining the occurrence and development of autism. The study of this topic help better understand the pathogenesis of ASD.

The effects of valproic acid neurotoxicity on aggressive behavior in zebrafish autism model

Valproic acid (VPA) is an effective drug, which is preferred for the treatments of epilepsy and various kinds of seizures. Nonetheless, VPA has many side effects associated with autism spectrum disorder (ASD). Therefore, we conducted molecular and behavior tests in adult proactive zebrafish after VPA exposure to investigate gene transcription changes, social behavior, aggression, anxiety and locomotion. Our findings revealed that VPA exposure generates ASD-like phenotypes and behaviors: genes associated with autism, such as adsl, mbd5 and shank3a altered; social interaction deficit. Further behavioral patterns suggest that VPA exposure induces decreases in aggression and increases the anxiety behavior and body cortisol significantly. VPA exposure did not affect locomotor activity in zebrafish. Additionally, we used correlative analyses to investigate the robustness between the ASD-related genes and the different behavior tests, results showed that ASD-related genes are negatively associated with aggressive behavior. Our study demonstrated that aggressive behavior assay is a better predictor of behavior for neurotoxicology of VPA.

Effect of Moringa oleifera leaf extract on valproate-induced oxidative damage in muscle

Valproic acid (VPA) is a drug used for the treatment of epilepsy worldwide. Depending on usage, it can cause complications such as coagulopathies, hepatotoxicity, and encephalopathy. Moringa oleifera has been shown to have antitumor, anti-inflammatory, antiulcer, antispasmodic, diuretic, antihypertensive, antidiabetic, and hepatoprotective activities. The current study investigated the effects of Moringa leaves extract (70% ethanol) on antioxidant systems against valproate-induced oxidative damage in muscle tissues of rats. Female Sprague Dawley rats were randomly divided into four groups. Group I: control group; Group II: animals given only Moringa extract; Group III: animals that received only sodium valproate; Group IV: animals administered with sodium valproate + Moringa extract. Moringa extract and sodium valproate were administered orally. Muscle tissues were collected after sacrificing the animals. Biochemical analysis of muscle tissue homogenates of the valproate group revealed elevated levels/activities of lipid peroxidation, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, lactate dehydrogenase, catalase, glutathione reductase, glutathione-S-transferase, reactive oxygen species, total oxidant status, oxidative stress index, glucose-6-phosphate dehydrogenase, sialic acid, protein carbonyl, nitric oxide, and myeloperoxidase. While glutathione, superoxide dismutase, glutathione peroxidase, total antioxidant status, aryl esterase and sodium/potassium ATPase were decreased. The administration of Moringa extract reversed these biochemical changes. These results indicate that Moringa leaves extract had a protective effect on muscle tissues against valproate-induced damage.

Toxicity and teratogenicity effects of valproic acid on zebrafish (Danio rerio) embryos in relation to autism spectrum disorder

Valproic acid (VPA) is a widely prescribed antiepileptic drug with various medicinal efficacies. Accumulated evidence implied that prenatal exposure to VPA is highly associated with autism spectrum disorder (ASD). In this study, the zebrafish were exposed to a set of VPA concentrations (0, 5, 10, 20, 40, 80, 160, 320, 640, 1280, and 2560 μM) at 5 h post fertilization (hpf) to 120 hpf. The adverse effects of VPA were extensively studied through the evaluations on the mortality, heartbeats, spontaneous tail coiling, and hatching rate. Morphological observations were conducted at 120 hpf, following the exposure termination. Basic locomotor responses and anxiety-like behavioral alterations evaluated for behavioral impairments are the hallmark feature of ASD. The exposure to VPA at teratogenic concentrations reduced the aforementioned parameters in a dose-dependent manner (p ≤ .05). At the selected non-teratogenic concentrations of VPA, the treated larvae demonstrated profound alterations of basic locomotor responses. No significant changes of anxiety and thigmotactic behaviors were observed on the VPA-treated fish compared to the control (p ≥ .005). This study depicted that embryonic zebrafish exposure to VPA produced significant toxicity and teratogenicity effects as well as the alterations of basic behavioral responses. Overall, this study provides a fundamental insight of the toxicity effects at morphological and behavioral levels to facilitate the understanding of ASD mechanisms at different molecular levels.

Syringic acid alleviates valproic acid induced autism via activation of p38 mitogen-activated protein kinase: Possible molecular approach

Autism spectrum disorder (ASD) is a multifactorial neurodevelopmental disorder characterized by restrictive and repetitive behavior followed by impairment in social, verbal, and non-verbal interaction and communication. Valproic acid (VPA) is a well-known anti-epileptic drug, but its prenatal exposure to animals causes social impairment, neurotransmitters imbalance, and neuroinflammation with ASD-like phenotypes. Syringic acid (SA) is a polyphenolic compound with anti-inflammatory, anti-apoptotic, antioxidant, and neuromodulator activity. The purpose of study was to investigate the protective effect of Syringic acid (SA) in prenatal VPA-treated rats through behavioral, neuroinflammation, oxidative stress, neurotransmitters, neuronal integrity, and apoptotic marker. Single dose of VPA was administered 600 mg/kg, i.p. on a gestational day (GD) 12th and SA was administrated from PnD 26th to 54th at the dose of 25, 50, and 100 mg/kg, p.o. On PnD 56th behavioral parameters (Pain sensitivity, open field test, narrow beam walks test and social impairment test) were performed and all animals were sacrificed, and brain tissue was isolated for oxidative stress (GSH, CAT, and LPO), neuroinflammation (TNF-α and IL-6) and neurotransmitters (GABA and Glutamate), histopathology (H&E, Nissl), immunohistochemistry (p38 MAPK) analysis. Rat treated with SA dose-dependently prevented behavioral alteration, restored antioxidant enzymes, neurotransmitters level, decreased neuroinflammatory markers, and improved neuronal integrity. Furthermore, immunohistochemistry confirmed the reduced p38 MAPK marker expression by SA in VPA induced autistic behavior.

Sex-related beneficial effects of exercise on cardiac function and rhythm in autistic rats

BACKGROUND

Cardiovascular diseases are prevalent in autistic patients. As exercise is useful in the treatment of medical conditions, this study aimed to identify the effect of low-intensity endurance exercise (LIEE) and moderate-intensity endurance exercise (MIEE) on cardiovascular events in autistic rats.

METHODS

Valproic acid (VPA) was administrated once on gestational day 12.5 to pregnant rats to produce autism-like symptoms in offspring. Thirty-day-old offspring were divided into 12 groups: Male-CTL, Male-VPA, Male-CTL + LIEE, Male-CTL + MIEE, Male-VPA + LIEE, Male-VPA + MIEE, Female-CTL, Female-VPA, Female-CTL + LIEE, Female-CTL + MIEE, Female-VPA + LIEE, and Female-VPA + MIEE. LIEE and MIEE were performed 5 days a week for 30 days. Twenty-four hours after the last exercise session, electrocardiogram and hemodynamic and cardiac function indices were recorded.

RESULTS

The results indicated that +dp/dt max and contractility index (CI) decreased in the Female-VPA group compared to the Female-CTL group. LIEE increased these parameters in the Female-VPA + LIEE group. However, MIEE normalized CI in the Male-VPA + MIEE compared to the Male-VPA group. Tau increased in the Female-VPA group compared to the Female-CTL group and it decreased in the Female-VPA + MIEE group compared to the Female-VPA group. LIEE and MIEE recovered the reduction of heart rate and the increase in P, R, and T amplitudes in Male-VPA group. LIEE and MIEE increased heart rate variability in the Male-VPA and Female-VPA groups.

CONCLUSIONS

The findings showed that LIEE and MIEE alleviated cardiac dysfunction and disturbances in heart rhythm in the autistic offspring. Exercise may be recommended as a routine program for autistic patients to prevent and treat the harmful cardiovascular consequences of autism.

Antiepileptic drugs are endocrine disruptors for the human fetal testis ex vivo

Valproic acid (VPA) has long been the most widely used antiepileptic drug (AED) for the treatment of epilepsy, bipolar psychiatric disorders, and migraine. However, long-term VPA treatment has several adverse effects on the male reproductive system notably on endocrine functions and/or spermatic parameters. In utero exposure of the fetus to VPA is well known to be associated with a higher risk of several congenital malformations including those of male reproductive organs. Subsequent generations of AEDs, such as carbamazepine (CARB) and lamotrigine (LAM), are considered safer and are currently recommended for women of child-bearing age with epilepsy. Because anomalies of the male genital tract mostly result from endocrine imbalance during fetal life, we hypothesized that AEDs could directly impair testis differentiation. We thus aimed at identifying and characterizing the effects of VPA, CARB, and LAM on the differentiation and function of the different testicular cell types, and at understanding the mechanisms underlying these effects. By using ex vivo culture of first-trimester human fetal testes, we show that VPA induces multiple endocrine disruptive effects, compared with the milder ones caused by CARB and LAM. AED also subtly altered the germ cell lineage in distinct manners. Transcriptomic analysis of VPA-induced alterations highlighted a very broad range of effects on the fetal testis. Overall, our results show that AEDs can behave as endocrine disruptors for the human fetal testis ex vivo. This is consistent with, and likely underlies, the VPA-induced male genital tract masculinization abnormalities observed in patients.

Effects of valproic acid on syncytialization in human placental trophoblast cell lines

The placenta is a critical organ for fetal development and a healthy pregnancy, and has multifaceted functions (e.g., substance exchange and hormone secretion). Syncytialization of trophoblasts is important for maintaining placental functions. Epilepsy is one of the most common neurological conditions worldwide. Therefore, this study aimed to reveal the influence of antiepileptic drugs, including valproic acid (VPA), carbamazepine, lamotrigine, gabapentin, levetiracetam, topiramate, lacosamide, and clobazam, at clinically relevant concentrations on syncytialization using in vitro models of trophoblasts. To induce differentiation into syncytiotrophoblast-like cells, BeWo cells were treated with forskolin. Exposure to VPA was found to dose-dependently influence syncytialization-associated genes (ERVW-1, ERVFRD-1, GJA1, CGB, CSH, SLC1A5, and ABCC4) in differentiated BeWo cells. Herein, the biomarkers between differentiated BeWo cells and the human trophoblast stem model (TSCT) were compared. In particular, MFSD2A levels were low in BeWo cells but abundant in TSCT cells. VPA exposure affected the expression of ERVW-1, ERVFRD-1, GJA1, CSH, MFSD2A, and ABCC4 in differentiated cells (ST-TSCT). Furthermore, VPA exposure attenuated BeWo and TSCT cell fusion. Finally, the relationships between neonatal/placental parameters and the expression of syncytialization markers in human term placentas were analyzed. MFSD2A expression was positively correlated with neonatal body weight, head circumference, chest circumference, and placental weight. Our findings have important implications for better understanding the mechanisms of toxicity of antiepileptic drugs and predicting the risks to placental and fetal development.

Spatiotemporal protein dynamics during early organogenesis in mouse conceptuses treated with valproic acid

Valproic acid (VPA) is an anti-epileptic medication that increases the risk of neural tube defect (NTD) outcomes in infants exposed during gestation. Previous studies into VPA's mechanism of action have focused on alterations in gene expression and metabolism but have failed to consider how exposure changes the abundance of critical developmental proteins over time. This study evaluates the effects of VPA on protein abundance in the developmentally distinct tissues of the mouse visceral yolk sac (VYS) and embryo proper (EMB) using mouse whole embryo culture. Embryos were exposed to 600 μM VPA at 2 h intervals over 10 h during early organogenesis with the aim of identifying protein pathways relevant to VPA's mechanism of action in failed NTC. Protein abundance was measured through tandem mass tag (TMT) labeling followed by liquid chromatography and mass spectrometry. Overall, there were over 1500 proteins with altered abundance after VPA exposure in the EMB or VYS with 428 of these proteins showing previous gene expression associations with VPA exposure. Limited overlap of significant proteins between tissues supported the conclusion of independent roles for the VYS and EMB in response to VPA. Pathway analysis of proteins with increased or decreased abundance identified multiple pathways with mechanistic relevance to NTC and embryonic development including convergent extension, Wnt Signaling/planar cell polarity, cellular migration, cellular proliferation, cell death, and cytoskeletal organization processes as targets of VPA. Clustering of co-regulated proteins to identify shared patterns of protein abundance over time highlighted 4 h and 6/10 h as periods of divergent protein abundance between control and VPA-treated samples in the VYS and EMB, respectively. Overall, this study demonstrated that VPA temporally alters protein content in critical developmental pathways in the VYS and the EMB during early organogenesis in mice.

Combined effects of valproate and naringin on kidney antioxidative markers and serum parameters of kidney function in C57BL6 mice

Valproate is known to disturb the kidney function, and high doses or prolonged intake may cause serum ion imbalance, kidney tubular acidosis, proteinuria, hyperuricosuria, polyuria, polydipsia, and dehydration. The aim of this in vivo study was to see whether naringin would counter the adverse effects of high-dose valproate in C57Bl/6 mice and to which extent. As expected, valproate (150 mg/kg bw a day for 10 days) caused serum hyperkalaemia, more in male than female mice. Naringin reversed (25 mg/kg bw a day for 10 days) the hyperkalaemia and activated antioxidative defence mechanisms (mainly catalase and glutathione), again more efficiently in females. In males naringin combined with valproate was not as effective and even showed some prooxidative effects.

Exposure to Valproic acid (VPA) resulted in alterations in the expression of angiogenic genes (NRP-1, VEGFA, VEGFR-2 and sFlt1) and histological modifications in the placenta of mice (Mus musculus)

Valproic acid (VPA), an anti-epileptic drug (AED), has been reported to exhibit anti-angiogenic properties. This study aimed to examine the impact of VPA on the expression of NRP-1 and additional angiogenic factors, as well as angiogenesis, in mouse placenta. Pregnant mice were divided into four groups: control (K), solvent control (KP), VPA treatment at a dose of 400 mg/kg body weight (BW) (P1), and VPA treatment at a dose of 600 mg/kg BW (P2). The mice were subjected to daily treatment via gavage from embryonic day (E) 9 to E14 and E9 to E16. Histological analysis was performed to evaluate Microvascular Density (MVD) and percentage of the placental labyrinth area. In addition, a comparative analysis of Neuropilin-1 (NRP-1), vascular endothelial growth factor (VEGFA), vascular endothelial growth factor receptor (VEGFR-2), and soluble (sFlt1) expression was conducted in relation to glyceraldehyde-3-phosphate dehydrogenase (GAPDH). The results of the MVD analysis and percentage of labyrinth area in the E14 and E16 placentas indicated that the treated groups were significantly lower than the control group. The relative expression levels of NRP-1, VEGFA, and VEGFR-2 in the treated groups were lower than those in the control group at E14 and E16. Meanwhile, the relative expression of sFlt1 in the treated groups at E16 was significantly higher than in the control group. Changes in the relative expression of these genes inhibit angiogenesis regulation in the mouse placenta, as evidenced by reduced MVD and a smaller percentage of the labyrinth area.

Nervous system development related gene expression regulation in the zebrafish embryo after exposure to valproic acid and retinoic acid: A genome wide approach

The evaluation of chemical and pharmaceutical safety for humans is moving from animal studies to New Approach Methodologies (NAM), reducing animal use and focusing on mechanism of action, whilst enhancing human relevance. In developmental toxicology, the mechanistic approach is facilitated by the assessment of predictive biomarkers, which allow mechanistic pathways perturbation monitoring at the basis of human hazard assessment. In our search for biomarkers of maldevelopment, we focused on chemically-induced perturbation of the retinoic acid signaling pathway (RA-SP), a major pathway implicated in a plethora of developmental processes. A genome-wide expression screening was performed on zebrafish embryos treated with two teratogens, all-trans retinoic acid (ATRA) and valproic acid (VPA), and a non-teratogen reference compound, folic acid (FA). Each compound was found to have a specific mRNA expression profile with 248 genes commonly dysregulated by both teratogenic compounds but not by FA. These genes were implicated in several developmental processes (e.g., the circulatory and nervous system). Given the prominent response of neurodevelopmental gene sets, and the crucial need to better understand developmental neurotoxicity, our study then focused on nervous system development. We found 62 genes that are potential early neurodevelopmental toxicity biomarker candidates. These results advance NAM-based safety assessment evaluation by highlighting the usefulness of the RA-SP in providing early toxicity biomarker candidates.

Prenatally VPA exposure is likely to cause autistic-like behavior in the rats offspring via TREM2 down-regulation to affect the microglial activation and synapse alterations

Microglial dysfunction has been reported in the valproic acid (VPA)-induced autism spectrum disorder (ASD) rat models. However, how does prenatal VPA exposure affect microglia remains to be elucidated. The triggering receptor expressed on myeloid cells 2 (TREM2) is revealed to be implicated in a range of microglia functions. However, reports on the association between TREM2 and VPA-induced ASD rat models are scarce. Our results showed that prenatal VPA exposure induced autistic-like behaviors, downregulated the levels of TREM2, up-regulated microglial activation, dysregulated microglial polarization, and altered synapse in offspring. TREM2 overexpression partly ameliorated microglia dysfunction and autistic-like behaviors in prenatal VPA-exposed rats. Our findings demonstrated that prenatally VPA exposure is likely to cause autistic-like behavior in the rat offspring via TREM2 down-regulation to affect the microglial activation, microglial polarization and synaptic pruning of microglia for the first time.

Sodium valproate exposure influences the expression of pparg in the zebrafish model

Valproic acid (VPA) is an anti-epileptic drug used alone or in combination with other medications to treat seizures, mania, and bipolar disorder. VPA recognized as a teratogenic chemical can cause severe birth defects mainly affecting the brain and spinal cord when administered during pregnancy. However, the potential mechanisms of developmental toxicity are still less studied, and in the present study, the influence of VPA exposure was evaluated on zebrafish early-life stages. Zebrafish were exposed to two sublethal concentrations of sodium valproate (SV) (0.06 mM and 0.15 mM) from 24 hours post-fertilization (hpf) to 96 hpf and the SV teratogenic potential was investigated through morphometric analysis of zebrafish larvae combined with the evaluation of cartilage profile. Moreover, the effect of SV on the transcription level of pparg was also performed. The results of the study showed the teratogenic potential of SV, which disrupts the morphometric signature of the head and body. The marked distortion of cartilage structures was paralleled to a malformation of telencephalon and optic tectum in both concentrations suggesting a high teratogen effect of SV on the brain. These data were further confirmed by the increased expression of pparg in the zebrafish head. Overall, the present study confirms the teratogenic activity of SV in the zebrafish model and, for the first time, points out the potential protective role of pparg in the SV dose-dependent toxicity.

Valproic acid induced liver injury: An insight into molecular toxicological mechanism

Valproic acid (VPA) is an anti-seizure drug that causes idiosyncratic liver injury. 2-propyl-4-pentenoic acid (Δ⁴VPA), a metabolite of VPA, has been implicated in VPA-induced hepatotoxicity. This review summarizes the pathogenesis involved in VPA-induced liver injury. The VPA induce liver injury mainly by i) liberation of Δ⁴VPA metabolites; ii) decrease in glutathione stores and antioxidants, resulting in oxidative stress; iii) inhibition of fatty acid β-oxidation, inducing mitochondrial DNA depletion and hypermethylation; a decrease in proton leak; oxidative phosphorylation impairment and ATP synthesis decrease; iv) induction of fatty liver via inhibition of carnitine palmitoyltransferase I, enhancing nuclear receptor peroxisome proliferator-activated receptor-gamma and acyl-CoA thioesterase 1, and inducing long-chain fatty acid uptake and triglyceride synthesis. VPA administration aggravates liver injury in individuals with metabolic syndromes. Therapeutic drug monitoring, routine serum levels of transaminases, ammonia, and lipid parameters during VPA therapy may thus be beneficial in improving the safety profile or preventing the progression of DILI.

Prenatal, but not postnatal exposure to chlorpyrifos affects social behavior of mice and the excitatory-inhibitory balance in a sex-dependent manner

The balance between excitatory and inhibitory neurotransmitters is essential for proper brain development. An imbalance between these two systems has been associated with neurodevelopmental disorders. On the other hand, literature also associates the massive use of pesticides with the increase of these disorders, with a particular focus on chlorpyrifos (CPF) a world-wide used organophosphate pesticide. This study was aimed at assessing social autistic-like behaviors on mice pre or postnatally exposed to CPF (0 or 1 mg/kg/day), in both sexes. In prenatal exposure, C57BL/6J pregnant mice were exposed to CPF through the diet, between gestational days (GD) 12 and 18, while a positive control group for some autistic behaviors was exposed to valproic acid (VPA) on GD 12 and 13. To assess postnatal exposure, C57BL/6J mice were orally exposed to the vehicle (corn oil) or CPF, from postnatal days (PND) 10-15. Social behavior and gene expression analysis were assessed on PND 45. Results showed social alterations only in males prenatally treated. GABA system was upregulated in CPF-treated females, whereas an increase in both systems was observed in both treated males. These findings suggest that males are more sensitive to prenatal CPF exposure, favoring the sex bias observed in ASD.

Autism-like symptoms by exposure to air pollution and valproic acid-induced in male rats

Exposure to air pollution during prenatal or neonatal periods is associated with autism spectrum disorder (ASD) according to epidemiology studies. Furthermore, prenatal exposure to valproic acid (VPA) has also been found to be associated with an increased prevalence of ASD. To assess the association between simultaneous exposure to VPA and air pollutants, seven exposure groups of rats were included in current study (PM2.5 and gaseous pollutants exposed - high dose of VPA (PGE-high); PM2.5 and gaseous pollutants exposed - low dose of VPA (PGE-low); gaseous pollutants only exposed - high dose of VPA (GE-high); gaseous pollutants only exposed - low dose of VPA (GE-low); clean air exposed - high dose of VPA (CAE-high); clean air exposed - low dose of VPA (CAE-low) and clean air exposed (CAE)). The pollution-exposed rats were exposed to air pollutants from embryonic day (E0) to postnatal day 42 (PND42). In all the induced groups, decreased oxidative stress biomarkers, decreased oxytocin receptor (OXTR) levels, and increased the expression of interleukin 6 (IL-6), interleukin 1β (IL-1β), and tumor necrosis factor alpha (TNF-α) were found. The volumes of the cerebellum, hippocampus, striatum, and prefrontal decreased in all induced groups in comparison to CAE. Additionally, increased numerical density of glial cells and decreased of numerical density of neurons were found in all induced groups. Results show that simultaneous exposure to air pollution and VPA can cause ASD-related behavioral deficits and air pollution reinforced the mechanism of inducing ASD ̉s in VPA-induced rat model of autism.

Prenatal exposure to valproic acid alters Reelin, NGF expressing neuron architecture and impairs social interaction in their autistic-like phenotype male offspring

Maternal exposure to anti-epileptic drug Valproic acid (VPA) during pregnancy increases the risk for the development of autism spectrum disorders (ASD). In this study, we have examined whether prenatal exposure to VPA will alter expression of key genes, synaptic morphology of nerve growth factor (NGF) and Reelin expressing neurons in the cortex of male offspring. To characterize in animal models, rat fetuses were exposed to VPA on 12.5 gestational day. The offspring of the VPA-exposed individuals (42%) resembles ASD-related phenotype (facial malformation, crooked-like tail, flattened paw, toenails and in-turning-ankles). Furthermore, we have observed deficit in social interaction accompanied by deregulation in expression of genes such as Caspase-3, focal adhesion kinase (FAK), Reelin, glial fibrillary acidic protein (GFAP), proliferating cell nuclear antigen (PCNA) and NGF. Subsequently, immunohistochemistry analysis revealed that exposure to VPA alters the cytoarchitecture (area, diameter) and reduced the dendritic arborization of Reelin, NGF expressing neurons in cortex. The compromised neurodevelopment by altered expression of Caspase-3, FAK, Reelin, GFAP, PCNA and NGF may cause defects in neuronal architecture, synaptic formation, synaptic plasticity and neuronal communication which could be linked with observed ASD-like phenotype and deficit social interaction.

Comprehensive Analysis of Metabolic Changes in Male Mice Exposed to Sodium Valproate Based on GC-MS Analysis

Purpose

Sodium valproate (VPA) is the most widely used broad-spectrum antiepileptic first-line drug in clinical practice and is effective against various types of epilepsy. However, VPA can induce severe cardiotoxicity, nephrotoxicity, hepatotoxicity, and neurotoxicity, which limits its use. Metabolomic studies of VPA-induced toxicity have focused primarily on changes in serum and urine metabolites but have not evaluated changes in major organs or tissues.

Methods

Central target tissues (intestine, lung, liver, hippocampus, cerebral cortex, inner ear, spleen, kidney, heart, and serum) were analyzed using gas chromatography mass spectrometry to comprehensively evaluate VPA toxicity in mouse models.

Results

Multivariate analyses, including orthogonal projections of the latent structure and Student’s t test, indicated that depending on the matrix used in the study (the intestine, lung, liver, hippocampus, cerebral cortex, inner ear, spleen, kidney, heart or serum) the number of metabolites differed, the lung being the poorest and the kidney the richest in number.

Conclusion

These metabolites were closely related and were found to participate in 12 key pathways related to amino acid, fatty acid, and energy metabolism, revealing that the toxic mechanism of VPA may involve oxidative stress, inflammation, amino acid metabolism, lipid metabolism, and energy disorder.

Neurogenesis of Subventricular Zone Progenitors in the Premature Cortex of Ferrets Facilitated by Neonatal Valproic Acid Exposure

The present study evaluated the neurogenesis of neonatal valproic acid (VPA) exposure on subventricular zone progenitors of the developing cerebral cortex in ferrets. VPA was injected at a dose of 200 µg/g of body weight into ferret infants on postnatal days 6 and 7. Two different thymidine analogues, 5-ethynyl-2′-deoxyuridine (EdU) and 5-bromo-2′-deoxyuridine (BrdU), were injected with a 48 h interval to label proliferating cells before and after VPA exposure. Two hours after BrdU injection, BrdU single- and EdU/BrdU double-labeled cells, but not EdU single-labeled cells, were significantly denser in both the inner and outer subventricular zones of VPA-exposed infants than in control infants. Notably, more than 97% of BrdU single- and EdU/BrdU double-labeled cells were immunopositive for Pax6, a stable marker for basal radial glia (bRG), in both groups. In contrast, the percentage of cells positively immunostained for Cux1, a postmitotic marker for upper-layer cortical neurons, in both EdU single- and BrdU single-labeled cells, was significantly higher in VPA-exposed infants than in control infants. These findings suggest that neonatal VPA exposure facilitates bRG proliferation, including self-renewal, followed by their differentiation into upper layer cortical neurons in the premature cortex of ferrets.

Alterations of the Hippocampal Networks in Valproic Acid-Induced Rat Autism Model

Autism Spectrum Disorder (ASD) is one of the most frequently diagnosed neurodevelopmental disorders, characterized among others by impairments in social interactions and repetitive behavior. According to one of the leading hypotheses about its origin, ASD is caused by the imbalance of excitatory and inhibitory circuit activity. ASD-related morphological and functional changes can be observed in several brain regions i.e., in the prefrontal cortex and the hippocampus. It is well-established that prenatal valproic-acid (VPA) exposure of rats on day 12.5 leads to neurodevelopmental alterations with autism-like clinical and behavioral symptoms. The aim of this study was to investigate potential changes in the excitability of neuronal networks and individual neurons of the hippocampus elicited by prenatal VPA treatment. As there are marked sex differences in ASD, offspring of both sexes were systematically tested, using two different age groups, to elucidate eventual differences in neurodevelopment after VPA treatment. Excitatory connections and long-term synaptic plasticity as well as intrinsic excitability of CA1 pyramidal cells were examined. Pregnant female Wistar rats received saline or 500 mg/kg VPA i. p. on gestation day 12.5. Brain slices of 6-week-old and 3-month-old offspring were investigated using extra- and intracellular electrophysiological techniques. Field potential- and whole-cell patch clamp recordings were carried out to measure network excitability and single cell activity in the CA1 region hippocampus. Enhanced excitability of hippocampal networks was detected in the 6-week-old VPA-treated male rats; however, this change could not be observed in 3-month-old males. Intrinsic excitability of single neurons, however, was increased in 3-month-old males. In 6-week-old treated females, the most prominent effect of VPA was an increase in voltage sag, to a similar degree to the neurons of the older age group. In 3-month-old females, a network excitability increase could be demonstrated, in a lesser degree than in younger males. It can be concluded, that VPA treatment had diverse effects on hippocampal excitability depending on the sex and the age of the animals. We found that certain alterations manifested in 6-week-old rats were compensated later, on the other hand, other changes persisted until the age of 3 months.

Metabolomics profiling of valproic acid-induced symptoms resembling autism spectrum disorders using 1H NMR spectral analysis in rat model

Prenatal exposure to valproic acid (VPA) has been implicated in the manifestation of autism spectrum disorder (ASD)-like behavioral and functional changes both in human and rodents including mice and rats. The objective of this study was to determine metabolomics profiling and biomarkers related to VPA-induced symptoms resembling ASD using proton nuclear magnetic resonance (1H-NMR) spectral data. VPA was administered to pregnant rats at gestation day 12.5 and effects measured subsequently in male 4-week-old offspring pups. The sociability of VPA-treated animals was significantly diminished and exhibited ASD-like behavior as evidenced by reduction of social adaptation disorder and lack of social interactions. To find biomarkers related to ASD, the following were collected prefrontal brain cortices, urine bladder and blood samples directly from heart puncture. In all samples, principal component analysis (PCA) and partial least-squares discriminant analysis (PLS-DA) displayed significant clustering pattern differences between control and treated groups. Valine, taurine, myo-inositol, 3-hydroxybutyrate and 1,3-dihydroxyacetone were significantly decreased in brain cortices in treated rats. Serum metabolites of glucose, creatine phosphate, lactate, glutamine and threonine were significantly increased in VPA-administered animals. Urinary metabolites of pimelate, 3-hydroxyisovalerate and valerate were significantly reduced in VPA-treated rat, whereas galactose and galactonate levels were elevated. Various metabolites were associated with mitochondrial dysfunction metabolism and central nervous system disorders. Data demonstrated that VPA-induced alterations in endogenous metabolites of serum, urine, and brain cortex which might prove useful as biomarkers for symptoms resembling ASD as a model of this disorder.

Application of high-throughput transcriptomics for mechanism-based biological read-across of short-chain carboxylic acid analogues of valproic acid

Chemical read-across is commonly evaluated without specific knowledge of the biological mechanisms leading to observed adverse outcomes in vivo. Integrating data that indicate shared modes of action in humans will strengthen read-across cases. Here we studied transcriptomic responses of primary human hepatocytes (PHH) to a large panel of carboxylic acids to include detailed mode-of-action data as a proof-of-concept for read-across in risk assessment. In rodents, some carboxylic acids, including valproic acid (VPA), are known to cause hepatic steatosis, whereas others do not. We investigated transcriptomics responses of PHHs exposed for 24 h to 18 structurally different VPA analogues in a concentration range to determine biological similarity in relation to in vivo steatotic potential. Using a targeted high-throughput screening assay, we assessed the differential expression of ~3,000 genes covering relevant biological pathways. Differentially expressed gene analysis revealed differences in potency of carboxylic acids, and expression patterns were highly similar for structurally similar compounds. Strong clustering occurred for steatosis-positive versus steatosis-negative carboxylic acids. To quantitatively define biological read-across, we combined pathway analysis and weighted gene co-expression network analysis. Active carboxylic acids displayed high similarity in gene network modulation. Importantly, free fatty acid synthesis modulation and stress pathway responses are affected by active car­boxylic acids, providing coherent mechanistic underpinning for our findings. Our work shows that transcriptomic analysis of cultured human hepatocytes can reinforce the prediction of liver injury outcome based on quantitative and mechanistic biological data and support its application in read-across.

Factors that influence the quality of metabolomics data in in vitro cell toxicity studies: a systematic survey

REACH (Registration, Evaluation, Authorization and Restriction of Chemicals) is a global strategy and regulation policy of the EU that aims to improve the protection of human health and the environment through the better and earlier identification of the intrinsic properties of chemical substances. It entered into force on 1st June 2007 (EC 1907/2006). REACH and EU policies plead for the use of robust high-throughput "omic" techniques for the in vitro investigation of the toxicity of chemicals that can provide an estimation of their hazards as well as information regarding the underlying mechanisms of toxicity. In agreement with the 3R's principles, cultured cells are nowadays widely used for this purpose, where metabolomics can provide a real-time picture of the metabolic effects caused by exposure of cells to xenobiotics, enabling the estimations about their toxicological hazards. High quality and robust metabolomics data sets are essential for precise and accurate hazard predictions. Currently, the acquisition of consistent and representative metabolomic data is hampered by experimental drawbacks that hinder reproducibility and difficult robust hazard interpretation. Using the differentiated human liver HepG2 cells as model system, and incubating with hepatotoxic (acetaminophen and valproic acid) and non-hepatotoxic compounds (citric acid), we evaluated in-depth the impact of several key experimental factors (namely, cell passage, processing day and storage time, and compound treatment) and instrumental factors (batch effect) on the outcome of an UPLC-MS metabolomic analysis data set. Results showed that processing day and storage time had a significant impact on the retrieved cell's metabolome, while the effect of cell passage was minor. Meta-analysis of results from pathway analysis showed that batch effect corrections and quality control (QC) measures are critical to enable consistent and meaningful estimations of the effects caused by compounds on cells. The quantitative analysis of the changes in metabolic pathways upon bioactive compound treatment remained consistent despite the concurrent causes of metabolomic data variation. Thus, upon appropriate data retrieval and correction and by an innovative metabolic pathway analysis, the metabolic alteration predictions remained conclusive despite the acknowledged sources of variability.

Sodium phenylbutyrate reduces repetitive self-grooming behavior and rescues social and cognitive deficits in mouse models of autism

Autism spectrum disorder (ASD) is a neurodevelopment disorder characterized by deficits in social interaction and restrictive, repetitive, and stereotypical patterns of behavior. However, there is no pharmacological drug that is currently used to target these core ASD symptoms. Sodium phenylbutyrate (NaPB) is a well-known long-term treatment of urea cycle disorders in children. In this study, we assessed the therapeutic effects of NaPB, which is a chemical chaperone as well as histone deacetylase inhibitor on a BTBR T + Itpr3tf/J (BTBR) mice model of ASD. We found that acute and chronic treatment of NaPB remarkably improved, not only core ASD symptoms, including repetitive behaviors and sociability deficit, but also cognitive impairment in the BTBR mice. NaPB substantially induced histone acetylation in the brain of the BTBR mice. Intriguingly, the therapeutic effects of NaPB on autistic-like behaviors, such as repetitive behaviors, impaired sociability, and cognitive deficit also showed in the valproic acid (VPA)-induced mouse model of autism. In addition, pentylenetetrazole (PTZ)-induced seizure was significantly attenuated by NaPB treatment in C57BL/6J and BTBR mice. These findings suggest that NaPB may provide a novel therapeutic approach for the treatment of patients with ASD.

5-HT7 receptor activation rescues impaired synaptic plasticity in an autistic-like rat model induced by prenatal VPA exposure

Autism spectrum disorder (ASD) is a severe life-long neuropsychiatric disorder. Alterations and imbalance of several neurochemical systems may be involved in ASD pathophysiology, of them, serotonergic neurotransmission dysfunction and deficiency may underlie behavioral abnormalities associated with ASD. However, the functional importance of serotonergic receptors, particularly 5HT7 receptors in ASD pathology remains poorly defined. Serotonin receptor subtype 7 (5-HT7R) plays a direct regulatory role in the development and also for the mature function of the brain, therefore, further studies are necessary to elucidate the role of these receptors in the etiology of autism. To address this issue, we combined here behavioral, electrophysiological methods to further characterize the contribution of 5-HT7Rs in the prenatal valproic acid (VPA) exposure-induced impairment in synaptic plasticity and their impact on the associated behavioral changes. This may help to unravel the underlying cellular mechanisms involved in ASD and can lead to new treatment and/or prevention therapies based on the role of the serotonergic system for autism. Findings revealed that compared to control, autistic-like offspring showed increased anxiety-like behavior, reduced social interaction, decreased locomotor activity, and impaired identification of the novel object. However, administration of 5-HT7Rs agonist, LP-211, for 7 consecutive days before testing from postnatal day 21 to 27 reversed all behavioral deficits induced by prenatal exposure to VPA in offspring. Also, both short-term depression and long-term potentiation were impaired in the autistic-like pups, but activation of 5-HT7Rs rescued the LTP impairment in the autistic-like group so that there was no significant difference between the two groups. Blockade of 5-HT7Rs caused LTP impairment following HFS in the autistic-like group. Besides, there was a significant difference in LTD induction following SB-269970 application between the control and the autistic-like groups measured at first 10 min following TPS. Moreover, both the number and the size of retrograde fast blue-labelled neurons in the raphe nuclei were reduced. Overall, these results provide for the first time, as far as we know, functional evidence for the restorative role of 5-HT7Rs activation against prenatal VPA exposure induced behavioral deficits and hippocampal synaptic plasticity impairment. Therefore, these receptors could be a potential and promising pharmacotherapy target for the treatment of autism.

A quantitative in vivo assay for craniofacial developmental toxicity of histone deacetylases

Many bony features of the face develop from endochondral ossification of preexisting collagen-rich cartilage structures. The proper development of these cartilage structures is essential to the morphological formation of the face. The developmental programs governing the formation of the pre-bone facial cartilages are sensitive to chemical compounds that disturb histone acetylation patterns and chromatin structure. We have taken advantage of this fact to develop a quantitative morphological assay of craniofacial developmental toxicity based on the distortion and deterioration of facial cartilage structures in zebrafish larvae upon exposure to increasing concentrations of several well-described histone deacetylase inhibitors. In this assay, we measure the angle formed by the developing ceratohyal bone as a precise, sensitive and quantitative proxy for the overall developmental status of facial cartilages. Using the well-established developmental toxicant and histone deacetylase-inhibiting compound valproic acid along with 12 structurally related compounds, we demonstrate the applicability of the ceratohyal angle assay to investigate structure-activity relationships.

Melatonin attenuates branch chain fatty acid induced apoptosis mediated neurodegeneration

Valproic acid (VPA)-a short branched chain fatty acid (BCFA), is widely recognized as an anticonvulsant and a mood-stabilizing drug, but various adverse effects of VPA have also been investigated. However, the impact of BCFAs aggregation on brain cells, in the pathogenesis of neurodegeneration remains elusive. The objective of this study is to understand the cellular mechanisms underlying VPA-induced neuronal cell death mediated by oxidative stress, and the neuroprotective role of exogenous melatonin treatment on VPA-induced cell death. Neurotoxicity of VPA and protective role exerted by melatonin were assessed in vitro in SH-SY5Y cells and in vivo in the cerebral cortex and cerebellum regions of Wistar rat brain. The results show that melatonin pre-treatment protects the cells from VPA-induced toxicity by exerting an anti-apoptotic and anti-inflammatory effect by regulating apoptotic proteins and pro-inflammatory cytokines. The findings of the present study emphasize novel insights of melatonin as a supplement for the prevention and treatment of neuronal dysfunction induced by VPA.

Perinatal exposure to BDE-47 exacerbated autistic-like behaviors and impairments of dendritic development in a valproic acid-induced rat model of autism

Perinatal exposure to polybrominated diphenyl ethers (PBDEs) may be a potential risk factor for autism spectrum disorders (ASD). BDE-47 is one of the most common PBDEs and poses serious health hazards on the central nervous system (CNS). However, effects of perinatal exposure to BDE-47 on social behaviors and the potential mechanisms are largely unexplored. Thus, we aimed to investigate whether BDE-47 exposure during gestation and lactation led to autistic-like behaviors in offspring rats in the present study. Valproic acid (VPA), which is widely used to establish animal model of ASD, was also adopted to induce autistic-like behaviors. A battery of tests was conducted to evaluate social and repetitive behaviors in offspring rats. We found that perinatal exposure to BDE-47 caused mild autistic-like behaviors in offspring, which were similar but less severe to those observed in pups maternally exposed to VPA. Moreover, perinatal exposure to BDE-47 aggravated the autistic-like behaviors in pups maternally exposed to VPA. Abnormal dendritic development is known to be deeply associated with autistic-like behaviors. Golgi-Cox staining was used to observe the morphological characteristics of dendrites in the prefrontal cortex of pups. We found perinatal exposure to BDE-47 reduced dendritic length and complexity of branching pattern, and spine density in the offspring prefrontal cortex, which may contribute to autistic-like behaviors observed in the present study. Perinatal exposure to BDE-47 also exacerbated the impairments of dendritic development in pups maternally exposed to VPA. Besides, our study also provided the evidence that the inhibition of BDNF-CREB signaling, a key regulator of dendritic development, may be involved in the dendritic impairments induced by perinatal exposure to BDE-47 and/or VPA, and the consequent autistic-like behaviors.

Postnatal AVP treatments prevent social deficit in adolescence of valproic acid-induced rat autism model

Studies have shown that arginine-vasopressin (AVP) is an important neuropeptide regulating social behaviors. The present work aimed to detect changes in the AVP numbers and level in a valproic acid (VPA)-induced rat model of autism and the underlying mechanism of its pathogenesis. Our results indicated that infants exposed to VPA showed obviously impaired communication and repetitive behaviors with reduced number of AVP-ir cells in paraventricular nucleus (PVN) and cerebrospinal fluid (CSF). The postnatal subcutaneous injection of AVP can alleviate social preference deficits and stereotyped behaviors, accompanied with the increase of the AVP concentrations in the CSF. We concluded that AVP system was involved in etiology of VPA-induced autism-like symptoms and postnatal AVP treatment rescued the behavioral deficits,which could be a promising treatment for autism.

The DNA repair protein ATM as a target in autism spectrum disorder

Impairment of the GABAergic system has been reported in epilepsy, autism, attention deficit hyperactivity disorder, and schizophrenia. We recently demonstrated that ataxia telangiectasia mutated (ATM) directly shapes the development of the GABAergic system. Here, we show for the first time to our knowledge how the abnormal expression of ATM affects the pathological condition of autism. We exploited 2 different animal models of autism, the methyl CpG binding protein 2-null (Mecp2y/-) mouse model of Rett syndrome and mice prenatally exposed to valproic acid, and found increased ATM levels. Accordingly, treatment with the specific ATM kinase inhibitor KU55933 (KU) normalized molecular, functional, and behavioral defects in these mouse models, such as (a) delayed GABAergic development, (b) hippocampal hyperexcitability, (c) low cognitive performances, and (d) social impairments. Mechanistically, we demonstrate that KU administration to WT hippocampal neurons leads to (a) higher early growth response 4 activity on Kcc2b promoter, (b) increased expression of Mecp2, and (c) potentiated GABA transmission. These results provide evidence and molecular substrates for the pharmacological development of ATM inhibition in autism spectrum disorders.

Pharmacology profile of F17464, a dopamine D3 receptor preferential antagonist

F17464 (N-(3-{4-[4-(8-Oxo-8H-[1,3]-dioxolo-[4,5-g]-chromen-7-yl)-butyl]-piperazin-1-yl}-phenyl)-methanesulfonamide, hydrochloride) is a new potential antipsychotic with a unique profile. The compound exhibits high affinity for the human dopamine receptor subtype 3 (hD3) (Ki = 0.17 nM) and the serotonin receptor subtype 1a (5-HT1a) (Ki = 0.16 nM) and a >50 fold lower affinity for the human dopamine receptor subtype 2 short and long form (hD2s/l) (Ki = 8.9 and 12.1 nM, respectively). [14C]F17464 dynamic studies show a slower dissociation rate from hD3 receptor (t1/2 = 110 min) than from hD2s receptor (t1/2 = 1.4 min) and functional studies demonstrate that F17464 is a D3 receptor antagonist, 5-HT1a receptor partial agonist. In human dopaminergic neurons F17464 blocks ketamine induced morphological changes, an effect D3 receptor mediated. In vivo F17464 target engagement of both D2 and 5-HT1a receptors is demonstrated in displacement studies in the mouse brain. F17464 increases dopamine release in the rat prefrontal cortex and mouse lateral forebrain - dorsal striatum and seems to reduce the effect of MK801 on % c-fos mRNA medium expressing neurons in cortical and subcortical regions. F17464 also rescues valproate induced impairment in a rat social interaction model of autism. All the neurochemistry and behavioural effects of F17464 are observed in the dose range 0.32-2.5 mg/kg i.p. in both rats and mice. The in vitro - in vivo pharmacology profile of F17464 in preclinical models is discussed in support of a therapeutic use of the compound in schizophrenia and autism.

Valproic acid alters nitric oxide status in neurulating mouse embryos

The molecular bases of the teratogenic effects elicited by valproic acid (VPA) are not fully defined. It was previously shown that inhibition of nitric oxide (NO) synthesis is associated with an enhancement of the teratogenic effects of VPA, while amplification of NO signal by sildenafil prompted a dose-dependent reduction of VPA-induced neural tube defects. In this study, for the first time, the effect of VPA on the NO synthesis was evaluated in mouse embryos during early organogenesis. On gestation day 8, ICR-CD1 mice received 600 mg/kg of VPA. Eight and 24 h later embryos were collected and analyzed for NO synthase (NOS) isoform expression, and for molecular mechanisms involved in their modulation. As main finding, in utero embryonic exposure to VPA determined a time-dependent shift of NOS isoforms expression, with a down regulated expression and activity of constitutive NOS (cNOS) and an increased expression and activity of inducible NOS (iNOS). The teratological relevance of this information remains to be established.

Valproic acid exposure impairs ultrasonic communication in infant, adolescent and adult rats

Persistent deficits of social communication are a hallmark of autism spectrum disorders (ASD). Communication disabilities can be experimentally modeled using rodents' ultrasonic vocalizations (USVs). Although prenatal exposure to valproic acid (VPA) is one of the most widely used animal models of ASD, little is known about communication impairments in this model. We performed a longitudinal study to characterize VPA-induced socio-communicative deficits in male and female rats. USVs were recorded in neonatal rats during maternal separation, in adolescent rats during social play, and in adult rats during social interactions. VPA male and female pups emitted a reduced number of USVs. Their calls were shorter and of an elevated peak frequency. Although social play deficits in adolescent rats were restricted to males only, both males and females demonstrated quantitative and qualitative changes in USVs. Altered vocalization also accompanied deficient social interactions in adult VPA males. In contrast to the adolescents, however, these differences were limited to a reduced number of USVs, but not to the call's structure. Present data suggest that ultrasonic vocalization measurement is a useful tool in detecting lifelong communicative disability in a VPA exposure-induced ASD model. We postulate that USV assessment in female rats may be a more sensitive indicator of juvenile autistic-like disturbances than other behavioral measures.

Heart malformation is an early response to valproic acid in developing zebrafish

Valproic acid (VPA) is a branched short-chain fatty acid primarily used in epilepsy, but is also used in bipolar disorder, migraine, and psychotic disorders. Despite its wide range of use, it is a teratogen resulting in various congenital abnormalities. Although a large number of scientific studies evidenced the teratogenic effects, there are limited data on embryonic exposure to VPA at specific or different stages of early embryogenesis. Based on this, the present study was planned to investigate the embryonic exposure to VPA at specific and different hours post fertilization (hpf) in zebrafish embryonic model. In first set of experiments, embryos from spawning groups of adult zebrafish were exposed to different molar concentrations of VPA at 2.5 hpf, and in the second set of experiments, embryos were exposed to VPA 100 μM at 24 hpf, 36 hpf, 48 hpf, 72 hpf, and 96 hpf. The parameters examined were hatching rate, mortality, morphology, body length, pericardial sac size, heartrate, anatomical changes in heart, skeletal and notochord till 120 hpf. It was observed that the embryos exposed to VPA at 2.5 hpf suffered from cardiac abnormalities including heart malformation, bradycardia, circulatory failure, and pericardial sac enlargement which was more apparent in embryos exposed to 100 μM VPA. In the second set of experiments, embryos exposed to VPA 100 μM at 24 hpf and 36 hpf suffered from heart malformations, but there was no incidence of cardiac malformation in embryos exposed to VPA at 48 hpf, 72 hpf, and 96 hpf. From the results, it was evident that exposure to VPA at early developmental stage of embryogenesis produced congenital cardiac abnormalities. Since VPA is a selective HDAC inhibitor, histone acetylation with aberrant gene expression during cardiogenesis might be the underlying cause of cardiac malformation.

A novel human pluripotent stem cell-based assay to predict developmental toxicity

There is a great need for novel in vitro methods to predict human developmental toxicity to comply with the 3R principles and to improve human safety. Human-induced pluripotent stem cells (hiPSC) are ideal for the development of such methods, because they are easy to retrieve by conversion of adult somatic cells and can differentiate into most cell types of the body. Advanced three-dimensional (3D) cultures of these cells, so-called embryoid bodies (EBs), moreover mimic the early developing embryo. We took advantage of this to develop a novel human toxicity assay to predict chemically induced developmental toxicity, which we termed the PluriBeat assay. We employed three different hiPSC lines from male and female donors and a robust microtiter plate-based method to produce EBs. We differentiated the cells into cardiomyocytes and introduced a scoring system for a quantitative readout of the assay-cardiomyocyte contractions in the EBs observed on day 7. Finally, we tested the three compounds thalidomide (2.3-36 µM), valproic acid (25-300 µM), and epoxiconazole (1.3-20 µM) on beating and size of the EBs. We were able to detect the human-specific teratogenicity of thalidomide and found the rodent toxicant epoxiconazole as more potent than thalidomide in our assay. We conclude that the PluriBeat assay is a novel method for predicting chemicals' adverse effects on embryonic development.

Simvastatin can enhance the osseointegration of titanium rods in ovariectomized rats maintenance treatment with valproic acid

The present work was aimed to evaluate the effect of valproic acid(VPA), simvastatin (SIM)+VPA on Ti(titanium) rods osseointegration in ovariectomized(OVX) rats and further investigation of the possible mechanism. The MC3T3-E1 cells were co-cultured with VPA, SIM + VPA and induced to osteogenesis, and the cell viability, mineralization ability were observed by MTT and ALP staining, Alizarin Red staining and Western blotting. Twelve weeks after bilateral ovariectomy, all animals were randomly divided into three groups: group OVX and VPA, SIM + VPA, and all the rats received Ti implants and animals belong to group VPA, SIM + VPA received valproic acid(300 mg/kg/day), valproic acid(300 mg/kg/day) plus SIM (25 mg/kg/day), respectively, treatment until death at 12 weeks. Micro-CT, histology, biomechanical testing, bone metabolism index and Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) analysis were used to observe the therapeutic effect and explore the possible mechanism. Results shown that VPA decreased new bone formation around the surface of titanium rods and push-out force other than group OVX. Histology, Micro-CT and biochemical analysis results showed combined application of systemic VPA showed harmful effects than OVX group on bone formation in osteopenic rats, with the worse effects on CTX-1, P1NP and microarchitecture as well as biomechanical parameters by down-regulated gene expression of Runx2, OCN, Smad1, BMP-2 and OPG, while up-regulated RANKL. However, after SIM treatment, the above indicators were significantly improved. The present study suggests that systemic use of VPA may bring harm to the stability of titanium implants in osteoporosis, SIM can reverse the negative effect of VPA on the osseointegration of titanium rods in ovariectomized rats.

Micromolar Valproic Acid Doses Preserve Survival and Induce Molecular Alterations in Neurodevelopmental Genes in Two Strains of Zebrafish Larvae

Autism spectrum disorders (ASDs) comprise a genetically heterogeneous group of conditions characterized by a multifaceted range of impairments and multifactorial etiology. Epidemiological studies have identified valproic acid (VPA), an anticonvulsant used to treat epilepsy, as an environmental factor for ASDs. Based on these observations, studies using embryonic exposure to VPA have been conducted in many vertebrate species to model ASD. The zebrafish is emerging as a popular model in biomedical research to study the molecular pathways involved in nervous system disorders. VPA exposure in zebrafish larvae has been shown to produce a plethora of effects on social, motor and anxiety behavior, and several genetic pathways altered by VPA have been described. However, the doses and regimen of administration reported in the literature are very heterogenous, creating contradictory results and posing serious limits to the interpretation of VPA action on neurodevelopment. To shed light on the toxic effect of VPA, we tested micromolar concentrations of VPA, using exposure for 24 and 48 h in two different zebrafish strains. Our results show that micromolar doses of VPA mildly affect embryo survival but are sufficient to induce molecular alterations in neurodevelopmental genes previously shown to be influenced by VPA, with substantial differences between strains.

Similarities between the Effects of Prenatal Chlorpyrifos and Valproic Acid on Ultrasonic Vocalization in Infant Wistar Rats

Background: In recent years, ultrasonic vocalizations (USV) in pups has become established as a good tool for evaluating behaviors related to communication deficits and emotional states observed in autism spectrum disorder (ASD). Prenatal valproic acid (VPA) exposure leads to impairments and social behavior deficits associated with autism, with the effects of VPA being considered as a reliable animal model of ASD. Some studies also suggest that prenatal exposure to chlorpyrifos (CPF) could enhance autistic-like behaviors. Methods: In order to explore these similarities, in the present study we tested whether prenatal exposure to CPF at GD12.5–14.5 produces effects that are comparable to those produced by prenatal VPA exposure at GD12.5 in infant Wistar rats. Using Deep Squeek software, we evaluated total number of USVs, latency to the first call, mean call duration, principal frequency peak, high frequency peak, and type of calls. Results: Consistent with our hypothesis, we found that exposure to both CPF and VPA leads to a significantly smaller number of calls along with a longer latency to produce the first call. No significant effects were found for the remaining dependent variables. Conclusions: These results suggest that prenatal exposure to CPF could produce certain behaviors that are reminiscent of those observed in ASD patients.

Kappa Opioid Receptor-mediated Modulation of Social Responding in Adolescent Rats and in Rats Prenatally Exposed to Valproic Acid

The kappa opioid receptor (KOP) system modulates social play responding, however a paucity of studies have examined effects on social motivation and cognition in the absence of play. Prenatal exposure to the anti-epileptic and mood stabiliser valproic acid (VPA) is associated with impaired social responding and altered gene expression of KOP (oprk1) and dynorphin (pdyn) in several brain regions. The present study examined if pharmacological modulation of KOP altered social motivation and cognition, immediate early gene (IEG) and oprk1-pdyn expression in adolescent male rats and rats prenatally exposed to VPA. In control rats, the KOP antagonist DIPPA enhanced sociability, while both DIPPA and the KOP agonist U50488 decreased social novelty preference. In rats exposed prenatally to VPA, neither U50488 nor DIPPA altered sociability or social novelty preference. Analysis of IEG expression revealed that DIPPA reduced expression of egr-1 expression in the prefrontal cortex of control rats and U50488 increased junb expression in the PFC of both control and VPA-exposed rats. VPA-exposed rats exhibited increased expression of oprk1 and pdyn in the prefrontal cortex and amygdala compared with control rats. DIPPA and U50488 increased oprk1 expression in the amygdala of control rats and decreased oprk1 expression in the prefrontal cortex of VPA-exposed rats. Taken together, these data demonstrate that pharmacological modulation of the KOP system alters social motivation and cognition in control rats, an effect not observed in rats prenatally exposed to VPA. These data provide support that prenatal exposure to VPA is associated with alterations in the expression and functionality of KOP system.

Effects of prenatal exposure to valproic acid or poly(I:C) on ultrasonic vocalizations in rat pups: The role of social cues

Sociocommunicative deficits commonly observed in autism spectrum disorder (ASD) can be experimentally modeled using rodents' ultrasonic vocalizations (USVs). For example, USVs emitted by pups, separated from their mothers and nest, serve as a useful tool to identify autistic-like behaviors during the early period of development. Being sensitive to social context, these neonatal calls may help to reveal reduced social attachment or abnormal processing of social information. The aim of the present study was to characterize quantitative and structural changes in USVs emitted during isolation by male and female rat pups prenatally exposed to either valproic acid (VPA) or poly(I:C). To determine whether those pups differed from controls in sensitivity to social stimuli, isolation-induced USVs were recorded under two bedding conditions, i.e., novel bedding and soiled bedding from their home cages. Our results demonstrated early communication deficits in both models of autism. We reported a reduced number of USVs emitted by both VPA- and poly(I:C)-exposed males and females. Moreover, compared to the controls, VPA (but not poly(I:C)) pups emitted shorter calls with a higher peak frequency. While VPA offspring demonstrated fewer USVs on the "safe" bedding imbued with maternal/nest odors, this calming effect was not observed in poly(I:C) males, suggesting a more specific deficit in social communication. The present results demonstrate that qualitative along with quantitative analyses of neonatal vocalizations are a useful tool for assessing early sociocommunicative deficits in ASD models. Notably, more specific changes in USV emission may be detected when introducing social context.

Valproic Acid Impacts the Growth of Growth Plate Chondrocytes

A range of bone abnormalities including short stature have been reported to be associated with the use of antiepileptic drugs (AEDs) in children. Exactly how AEDs impact skeletal growth, however, is not clear. In the present study, rat growth plate chondrocytes were cultured to study the effects of AEDs, including valproic acid (VPA), oxcarbazepine (OXA), levetiracetam (LEV), lamotrigine (LTG), and topiramate (TPM) on the skeletal growth. VPA markedly reduced the number of chondrocytes by apoptosiswhile other AEDs had no effect. The apoptosis associated noncleaved and cleaved caspase 3, and caspases were increased by exposure to VPA, which up-regulated cyclooxygenase 2 (COX-2) mRNA and protein levels likely through histone acetylation. The COX-2 inhibitor NS-398 attenuated the effects of VPA up-regulating COX-2 expression and decreased VPA-induced caspase 3 expression. The use of VPA in children should be closely monitored or replaced, where appropriate, by AEDs which do not apparently affect the growth plate chondrocytes.