The Journal of Toxicological Sciences
Online ISSN : 1880-3989
Print ISSN : 0388-1350
ISSN-L : 0388-1350
Volume 44 , Issue 5
Showing 1-5 articles out of 5 articles from the selected issue
Original Article
  • Bodong Li, Haibo Xie, Xian Wang, Xiaodong Yang, Ling Yang, Jiaxiang Zh ...
    2019 Volume 44 Issue 5 Pages 317-326
    Published: 2019
    Released: May 08, 2019
    JOURNALS FREE ACCESS FULL-TEXT HTML

    The purpose of this study was to explore whether renal endothelial cell injury is associated with oxidative stress in trichloroethylene (TCE)-induced immune kidney damage by detecting adhesion molecules and oxidative stress indexes. In this study, a mouse model of skin sensitization with the antioxidant Tempol was used to explore the mechanism. Blood urea nitrogen (BUN), creatinine (Cre), and histological examination were used for kidney function evaluation. Kidney homogenates were used for detecting renal nitric oxide (NO), nitric oxide synthase (NOS), superoxide dismutase (SOD) and malondialdehyde (MDA). Renal endothelial nitric oxide synthase (eNOS), E-selectin, vascular cell adhesion molecule (VCAM-1) and intercellular adhesion molecule (ICAM-1) protein levels were measured by immunohistochemical and Western blot. We found that BUN and Cre levels increased in the TCE sensitization positive group and the TCE+Tempol sensitization positive group. In the TCE sensitization positive group, a partial area of vacuolar degeneration and lysed epithelial cells were observed in renal tubules. In TCE+Tempol sensitization positive group, small areas were also found to be vacuolar degenerated and renal tubules were dissolved. Renal NO, NOS, SOD and eNOS levels decreased and MDA levels increased, renal E-selectin, VCAM-1and ICAM-1 protein levels increased in the TCE sensitization positive group and the TCE+Tempol sensitization positive group. Tempol attenuated TCE induced up-regulation of MDA, E-selectin, VCAM-1and ICAM-1 and down-regulation of NO, NOS, SOD and eNOS. In conclusion, trichloroethylene-sensitized mice renal immune injury is associated with the renal endothelial cells’ oxidative stress state.

Letter
  • Tomoya Fujie, Fukuta Takenaka, Eiko Yoshida, Shuji Yasuike, Yasuyuki F ...
    2019 Volume 44 Issue 5 Pages 327-333
    Published: 2019
    Released: May 08, 2019
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    Metallothionein (MT) is a low-molecular-weight, cysteine-rich, and metal-binding protein that protects cells from the cytotoxic effects of heavy metals and reactive oxygen species. Previously, we found that transcriptional induction of endothelial MT-1A was mediated by not only the metal-regulatory transcription factor 1 (MTF-1)-metal responsive element (MRE) pathway but also the nuclear factor-erythroid 2-related factor 2 (Nrf2)-antioxidant response element/electrophile responsive element (ARE) pathway, whereas that of MT-2A was mediated only by the MTF-1-MRE pathway, using the organopnictogen compounds tris(pentafluorophenyl)stibane, tris(pentafluorophenyl)arsane, and tris(pentafluorophenyl)phosphane as molecular probes in vascular endothelial cells. In the present study, we investigated the binding sites of MTF-1 and Nrf2 in the promoter regions of MTs in cultured bovine aortic endothelial cells treated with these organopnictogen compounds. We propose potential mechanisms underlying transcriptional induction of endothelial MT isoforms. Specifically, both MRE activation by MTF-1 and that of ARE in the promoter region of the MT-2A gene by Nrf2 are involved in transcriptional induction of MT-1A, whereas only MRE activation by MTF-1 or other transcriptional factor(s) is required for transcriptional induction of MT-2A in vascular endothelial cells.

Original Article
  • Do-Hee Kim, Juthika Kundu, In Gyeong Chae, Jong Kwon Lee, Jung Sun Heo ...
    2019 Volume 44 Issue 5 Pages 335-345
    Published: 2019
    Released: May 08, 2019
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    Titanium dioxide nanoparticles (TiO2-NPs) are used to improve the aesthetic of toothpaste. While TiO2-NPs have been used safely in toothpaste products for a long time, there haven’t been studies to determine whether absorption of TiO2-NPs by the mucous membranes in the mouth induces pathogenic conditions. Here, we assessed whether TiO2-NPs induce cyclooxygenase-2 (COX-2) and investigated the molecular mechanisms underlying the pro-inflammatory effect of TiO2-NPs on human periodontal ligament (PDL) cells. Treatment of PDL cells with TiO2-NPs led to induction of both COX-2 mRNA and protein expression. TiO2-NPs stimulated the nuclear translocation of nuclear factor-kappaB (NF-κB) as well as its DNA binding by inducing phosphorylation and subsequent degradation of the inhibitory protein IκBα in PDL cells. TiO2-NPs treatment resulted in rapid activation of extracellular signal-regulated kinase (ERK)1/2 and Akt, which could be upstream of NF-κB. Treatment of PDL cells with both the MEK1/2 inhibitor U0126 and the PI3K inhibitor LY294002 strongly attenuated TiO2-NPs-induced activation of NF-κB, and also the expression of COX-2. PDL cells treated with TiO2-NPs exhibited increased accumulation of intracellular reactive oxygen species (ROS). Pretreatment of cells with ROS scavenger N-acetyl cysteine (NAC) abrogated the stimulatory effect of TiO2-NPs on p65, p50, and COX-2 expression. In conclusion, ROS, concomitantly overproduced by TiO2-NPs, induce COX-2 expression through activation of NF-κB signaling, which may contribute to the inflammatory effect of PDL cells.

Original Article
  • Akira Kubota, Yusuke K. Kawai, Natsumi Yamashita, Jae Seung Lee, Daisu ...
    2019 Volume 44 Issue 5 Pages 347-356
    Published: 2019
    Released: May 08, 2019
    JOURNALS FREE ACCESS FULL-TEXT HTML

    Increasing use of zebrafish in biomedical, toxicological and developmental studies requires explicit knowledge of cytochrome P450 (CYP), given the central role of CYP in oxidative biotransformation of xenobiotics and many regulatory molecules. A full complement of CYP genes in zebrafish and their transcript expression during early development have already been examined. Here we established a comprehensive picture of CYP gene expression in the adult zebrafish liver using a RNA-seq technique. Transcriptional profiling of a full complement of CYP genes revealed that CYP2AD2, CYP3A65, CYP1A, CYP2P9 and CYP2Y3 are major CYP genes expressed in the adult zebrafish liver in both sexes. Quantitative real-time RT-PCR analysis for selected CYP genes further supported our RNA-seq data. There were significant sex differences in the transcript levels for CYP1A, CYP1B1, CYP1D1 and CYP2N13, with males having higher expression levels than those in females in all cases. A similar feature of gender-specific expression was observed for CYP2AD2 and CYP2P9, suggesting sex-specific regulation of constitutive expression of some CYP genes in the adult zebrafish liver. The present study revealed several “orphan” CYP genes as dominant isozymes at transcript levels in the adult zebrafish liver, implying crucial roles of these CYP genes in liver physiology and drug metabolism. The current results establish a foundation for studies with zebrafish in drug discovery and toxicology.

Original Article
  • Takaharu Tanaka, Yasunori Masubuchi, Rena Okada, Kota Nakajima, Kazuki ...
    2019 Volume 44 Issue 5 Pages 357-372
    Published: 2019
    Released: May 08, 2019
    JOURNALS FREE ACCESS FULL-TEXT HTML

    Developmental hypothyroidism as a model of autism spectrum disorders disrupts hippocampal neurogenesis through the adult stage. The present study investigated the ameliorating effect of postweaning exposure to antioxidant on the hypothyroidism-induced disruptive neurogenesis. Mated female Sprague-Dawley rats were treated with 0 or 10 ppm 6-propyl-2-thiouracil (PTU) as an anti-thyroid agent in drinking water from gestational day 6 to postnatal day (PND) 21 on weaning. PTU-exposed male offspring were fed either basal diet, diet containing α-glycosyl isoquercitrin (AGIQ) at 5,000 ppm or α-lipoic acid (ALA) at 1,000 ppm as an antioxidant from PND 21 to PND 77. PTU-exposure decreased DCX+ and NeuN+ granule cell lineage subpopulations, synaptic plasticity-related FOS+ granule cells, and hilar PVALB+ and GAD67+ GABAergic interneurons, increased hilar SST+ and CALB2+ interneurons, and upregulated Gria3, Otx2, and antioxidant enzyme genes in the dentate gyrus on PND 77. These results suggest disruption of neurogenesis remained in relation with increase of oxidative stress and compensatory responses to the disruption at the adult stage. AGIQ recovered expression of some antioxidant enzyme genes and was effective for restoration of NeuN+ postmitotic granule cells and PVALB+ and SST+ interneurons. In contrast, ALA was effective for restoration of all interneuron subpopulations, as well as postmitotic granule cells, and upregulated Grin2a that may play a role for the restoration. Both antioxidants recovered expression of Otx2 and AGIQ-alone recovered Gria3, suggesting a reversal of disruptive neurogenesis by compensatory responses. Thus, postweaning antioxidant exposure may be effective for ameliorating developmental hypothyroidism-induced disruptive neurogenesis by restoring the function of regulatory system.

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