Gene expression profiles of multiple brain regions in rats differ between developmental and postpubertal exposure to valproic acid.

We have previously reported that the valproic acid (VPA)-induced disruption pattern of hippocampal adult neurogenesis differs between developmental and 28-day postpubertal exposure. In the present study, we performed brain region-specific global gene expression profiling to compare the profiles of VPA-induced neurotoxicity between developmental and postpubertal exposure. Offspring exposed to VPA at 0, 667, and 2000 parts per million (ppm) via maternal drinking water from gestational day 6 until weaning (postnatal day 21) were examined, along with male rats orally administered VPA at 0, 200, and 900 mg/kg body weight for 28 days starting at 5 weeks old.

Downregulation of low-density lipoprotein receptor class A domain-containing protein 4 (Ldlrad4) in the liver of rats treated with nongenotoxic hepatocarcinogen to induce transforming growth factor β signaling promoting cell proliferation and suppressing apoptosis in early hepatocarcinogenesis.

We previously found downregulation of low-density lipoprotein receptor class A domain-containing protein 4 (LDLRAD4), a negative regulator of transforming growth factor (TGF)-β signaling, in glutathione S-transferase placental form (GST-P) expressing ( ) pre-neoplastic lesions produced by treatment with nongenotoxic hepatocarcinogens for up to 90 days in rats. Here, we investigated the relationship between LDLRAD4 downregulation and TGFβ signaling in nongenotoxic hepatocarcinogenesis. The transcripts of Tgfb and Hb-egf increased after ≥28 days of treatment.

[Transcriptomics-driven Evaluation on Liver Toxicity Using Adverse Outcome Pathways (AOP)].

Because the liver is the primary target organ for chemicals and pharmaceuticals, evaluation of these substances' liver toxicity is of critical importance. New evaluation methods without animal testing (i.e.

Differential responses on energy metabolic pathway reprogramming between genotoxic and non-genotoxic hepatocarcinogens in rat liver cells.

To clarify difference in the responses on the reprogramming of metabolism toward carcinogenesis between genotoxic and non-genotoxic hepatocarcinogens in the liver, rats were repeatedly administered genotoxic hepatocarcinogens (-nitrosodiethylamine, aflatoxin B, -nitrosopyrrolidine, or carbadox) or non-genotoxic hepatocarcinogens (carbon tetrachloride, thioacetamide, or methapyrilene hydrochloride) for 28, 84, or 90 days. Non-genotoxic hepatocarcinogens revealed transcript expression changes suggestive of suppressed mitochondrial oxidative phosphorylation (OXPHOS) after 28 days and increased glutathione -transferase placental form-positive (GST-P) foci downregulating adenosine triphosphate (ATP) synthase subunit beta, mitochondrial precursor (ATPB), compared with genotoxic hepatocarcinogens after 84 or 90 days, suggesting that non-genotoxic hepatocarcinogens are prone to suppress OXPHOS from the early stage of treatment, which is in contrast to genotoxic hepatocarcinogens. Both genotoxic and non-genotoxic hepatocarcinogens upregulated glycolytic enzyme genes and increased cellular membrane solute carrier family 2, facilitated glucose transporter member 1 (GLUT1) expression in GST-P foci for up to 90 days, suggesting induction of a metabolic shift from OXPHOS to glycolysis at early hepatocarcinogenesis by hepatocarcinogens unrelated to genotoxic potential.

Genetic toxicology in silico protocol.

In silico toxicology (IST) approaches to rapidly assess chemical hazard, and usage of such methods is increasing in all applications but especially for regulatory submissions, such as for assessing chemicals under REACH as well as the ICH M7 guideline for drug impurities. There are a number of obstacles to performing an IST assessment, including uncertainty in how such an assessment and associated expert review should be performed or what is fit for purpose, as well as a lack of confidence that the results will be accepted by colleagues, collaborators and regulatory authorities. To address this, a project to develop a series of IST protocols for different hazard endpoints has been initiated and this paper describes the genetic toxicity in silico (GIST) protocol.

Twenty-eight-day repeated oral doses of sodium valproic acid increases neural stem cells and suppresses differentiation of granule cell lineages in adult hippocampal neurogenesis of postpubertal rats.

Developmental exposure to valproic acid (VPA), a model compound for experimental autism, has shown to primarily target GABAergic interneuron subpopulations in hippocampal neurogenesis of rat offspring. The VPA-exposed animals had revealed late effects on granule cell lineages, involving progenitor cell proliferation and synaptic plasticity. To investigate the possibility whether hippocampal neurogenesis in postpubertal rats in a protocol of 28-day repeated exposure is affected in relation with the property of a developmental neurotoxicant by developmental exposure, VPA was orally administered to 5-week-old male rats at 0, 200, 800 and 900 mg/kg body weight/day for 28 days.

Expression Characteristics of Genes Hypermethylated and Downregulated in Rat Liver Specific to Nongenotoxic Hepatocarcinogens.

This study examined hypermethylated and downregulated genes specific to carbon tetrachloride (CCl4) by Methyl-Seq analysis combined with expression microarray analysis in the liver of rats treated with CCl4 or N-nitrosodiethylamine (DEN) for 28 days, by excluding those with DEN. Among 52 genes, Ldlrad4, Proc, Cdh17, and Nfia were confirmed to show promoter-region hypermethylation by methylation-specific quantitative PCR analysis on day 28. The transcript levels of these 4 genes decreased by real-time reverse transcription-PCR analysis in the livers of rats treated with nongenotoxic hepatocarcinogens for up to 90 days compared with untreated controls and genotoxic hepatocarcinogens.

In silico toxicology protocols.

The present publication surveys several applications of in silico (i.e., computational) toxicology approaches across different industries and institutions.

Erratum to: The OECD validation program of the H295R steroidogenesis assay: Phase 3. Final inter-laboratory validation study.

In the original article wrong unites were quoted in Table 3 (page 508) and Table 4 (page 510) as well as in the paragraph 3.2 Core chemical exposure experiments on page 509. Also in paragraph 2.

Differential effects between developmental and postpubertal exposure to N-methyl-N-nitrosourea on progenitor cell proliferation of rat hippocampal neurogenesis in relation to COX2 expression in granule cells.

This study was performed to compare the exposure effects of N-methyl-N-nitrosourea (MNU), a cytocidal agent of proliferating cells, on rat hippocampal neurogenesis between developmental and postpubertal periods. Developmental exposure through maternal drinking water from gestational day 6 to day 21 after delivery on weaning decreased GFAP-immunoreactive stem cells and increased immunoreactive cells indicative of subsequent progenitor and postmitotic immature neuronal populations, TUNEL or p21 stem/progenitor cells and COX2 granule cells, on postnatal day (PND) 21. On PND 77 after cessation of developmental exposure, NeuN postmitotic granule cells decreased in number.

Maternal Exposure to Valproic Acid Primarily Targets Interneurons Followed by Late Effects on Neurogenesis in the Hippocampal Dentate Gyrus in Rat Offspring.

Valproic acid (VPA) is used to establish models of experimental autism. The present study investigated the developmental exposure effect of VPA on postnatal hippocampal neurogenesis in accordance with the exposure scheme of OECD Test Guideline 426 adopted for developmental neurotoxicity. Pregnant rats were administered drinking water containing 0, 667, or 2000 ppm VPA from gestational day 6 until day 21 post-delivery.

Immunohistochemistry of aberrant neuronal development induced by 6-propyl-2-thiouracil in rats.

6-Propyl-2-thiouracil (PTU)-induced hypothyroidism disrupts neuronal/glial development. This study sought to identify the sensitive immunohistochemical parameters of developmental neurotoxicity (DNT) following PTU-exposure, as well as their responses in a 28-day toxicity study in adults. In the developmental exposure study, pregnant rats were treated with 0, 1, 3, and 10ppm PTU in drinking water from gestational day 6 to postnatal day (PND) 21 and pups were examined on PNDs 21 and 77.

Global gene expression profiles in brain regions reflecting abnormal neuronal and glial functions targeting myelin sheaths after 28-day exposure to cuprizone in rats.

Both developmental and postpubertal cuprizone (CPZ) exposure impairs hippocampal neurogenesis in rats. We previously found that developmental CPZ exposure alters the expression of genes related to neurogenesis, myelination, and synaptic transmission in specific brain regions of offspring. Here, we examined neuronal and glial toxicity profiles in response to postpubertal CPZ exposure by using expression microarray analysis in the hippocampal dentate gyrus, corpus callosum, cerebral cortex, and cerebellar vermis of 5-week-old male rats exposed to 0, 120, and 600mg/kg CPZ for 28days.

Simpler alternative to CARCINOscreen(®) based on quantitative PCR (qPCR).

Carcinogenicity of chemicals in our environment is one of the most important health hazards to humans. Recently, a microarray-based short-term prediction system for the hepatocarcinogenicity of chemicals, named CARCINOscreen(®), was developed. Although the system is a promising tool reported to have an ability to predict hepatocarcinogenicity in rats with 92.

Developmental cuprizone exposure impairs oligodendrocyte lineages differentially in cortical and white matter tissues and suppresses glutamatergic neurogenesis signals and synaptic plasticity in the hippocampal dentate gyrus of rats.

Developmental cuprizone (CPZ) exposure impairs rat hippocampal neurogenesis. Here, we captured the developmental neurotoxicity profile of CPZ using a region-specific expression microarray analysis in the hippocampal dentate gyrus, corpus callosum, cerebral cortex and cerebellar vermis of rat offspring exposed to 0, 0.1, or 0.

Cuprizone decreases intermediate and late-stage progenitor cells in hippocampal neurogenesis of rats in a framework of 28-day oral dose toxicity study.

Developmental exposure to cuprizone (CPZ), a demyelinating agent, impairs intermediate-stage neurogenesis in the hippocampal dentate gyrus of rat offspring. To investigate the possibility of alterations in adult neurogenesis following postpubertal exposure to CPZ in a framework of general toxicity studies, CPZ was orally administered to 5-week-old male rats at 0, 120, or 600mg/kg body weight/day for 28days. In the subgranular zone (SGZ), 600mg/kg CPZ increased the number of cleaved caspase-3(+) apoptotic cells.

Gene expression profiling of the hippocampal dentate gyrus in an adult toxicity study captures a variety of neurodevelopmental dysfunctions in rat models of hypothyroidism.

We previously found that developmental hypothyroidism changed the expression of genes in the rat hippocampal dentate gyrus, a brain region where adult neurogenesis is known to occur. In the present study, we performed brain region-specific global gene expression profiling in an adult rat hypothyroidism model to see if it reflected the developmental neurotoxicity we saw in the developmental hypothyroidism model. Starting when male rats were 5 weeks old, we administered 6-propyl-2-thiouracil at a doses of 0, 0.

Developmental exposure to cuprizone reduces intermediate-stage progenitor cells and cholinergic signals in the hippocampal neurogenesis in rat offspring.

The exposure to cuprizone (CPZ) leads to demyelination in the central nervous system in rodents. To examine the developmental effects of CPZ exposure on hippocampal neurogenesis, pregnant rats were treated with 0, 0.1 or 0.

Gene expression profile of brain regions reflecting aberrations in nervous system development targeting the process of neurite extension of rat offspring exposed developmentally to glycidol.

We previously found that exposure to glycidol at 1000 ppm in drinking water caused axonopathy in maternal rats and aberrations in late-stage hippocampal neurogenesis, targeting the process of neurite extension in offspring. To identify the profile of developmental neurotoxicity of glycidol, pregnant Sprague-Dawley rats were given drinking water containing glycidol from gestational day 6 until weaning on day 21 after delivery, and offspring at 0, 300 and 1000 ppm were subjected to region-specific global gene expression profiling. Four brain regions were selected to represent both cerebral and cerebellar tissues, i.

Glycidol induces axonopathy and aberrations of hippocampal neurogenesis affecting late-stage differentiation by exposure to rats in a framework of 28-day toxicity study.

Developmental exposure to glycidol induces aberrations of late-stage neurogenesis in the hippocampal dentate gyrus of rat offspring, whereas maternal animals develop axonopathy. To investigate the possibility whether similar effects on adult neurogenesis could be induced by exposure in a framework of 28-day toxicity study, glycidol was orally administered to 5-week-old male Sprague-Dawley rats by gavage at 0, 30 or 200 mg/kg for 28 days. At 200 mg/kg, animals revealed progressively worsening gait abnormalities as well as histopathological and immunohistochemical changes suggestive of axonal injury as evidenced by generation of neurofilament-L(+) spheroids in the cerebellar granule layer and dorsal funiculus of the medulla oblongata, central chromatolysis in the trigeminal nerve ganglion cells and axonal degeneration in the sciatic nerves.

Methacarn as a whole brain fixative for gene and protein expression analyses of specific brain regions in rats.

For molecular analysis in anatomically-specific brain regions for rodent studies, it is necessary to establish a fast and accurate procedure for tissue sampling to achieve high integrity and expression fidelity of extracted molecules. The present study was performed to examine suitability of whole brain fixation with methacarn and subsequent tissue sampling using punch-biopsy devices for gene expression analysis in rats. After fixation, each specific region, i.

Glycidol induces axonopathy by adult-stage exposure and aberration of hippocampal neurogenesis affecting late-stage differentiation by developmental exposure in rats.

To investigate the neurotoxicity profile of glycidol and its effect on developmental hippocampal neurogenesis, pregnant Sprague Dawley rats were given drinking water containing 0, 100, 300, or 1000 ppm glycidol from gestational day 6 until weaning on day 21 after delivery. At 1000 ppm, dams showed progressively worsening gait abnormalities, and histopathological examination showed generation of neurofilament-L(+) spheroids in the cerebellar granule layer and dorsal funiculus of the medulla oblongata, central chromatolysis in the trigeminal nerve ganglion cells, and axonal degeneration in the sciatic nerves. Decreased dihydropyrimidinase-like 3(+) immature granule cells in the subgranular zone (SGZ) and increased immature reelin(+) or calbindin-2(+) γ-aminobutyric acid-ergic interneurons and neuron-specific nuclear protein (NeuN)(+) mature neurons were found in the dentate hilus of the offspring of the 1000 ppm group on weaning.

The OECD validation program of the H295R steroidogenesis assay: Phase 3. Final inter-laboratory validation study.

Unlabelled: BACKGROUND, GOALS, AND SCOPE: In response to increasing concerns regarding the potential of chemicals to interact with the endocrine system of humans and wildlife, various national and international programs have been initiated with the aim to develop new guidelines for the screening and testing of these chemicals in vertebrates. Here, we report on the validation of an in vitro assay, the H295R steroidogenesis assay, to detect chemicals with the potential to inhibit or induce the production of the sex steroid hormones testosterone (T) and 17β-estradiol (E2) in preparation for the development of an Organization for Economic Cooperation and Development (OECD) test guideline.

Methods: A previously optimized and pre-validated protocol was used to assess the potential of 28 chemicals of diverse structures and properties to validate the H295R steroidogenesis assay.

Relationship between the results of in vitro receptor binding assay to human estrogen receptor alpha and in vivo uterotrophic assay: comparative study with 65 selected chemicals.

For screening chemicals possessing endocrine disrupting potencies, the uterotrophic assay has been placed in a higher level in the OECD testing framework than the ER binding assay to detect ER-mediated activities. However, there are no studies that can demonstrate a clear relationship between these assays. In order to clarify the relationship between the in vitro ER binding and in vivo uterotrophic assays and to determine meaningful binding potency from the ER binding assay, we compared the results from these assays for 65 chemicals spanning a variety of chemicals classes.