The Journal of Toxicological Sciences
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Volume 32 , Issue 5
December
Showing 1-12 articles out of 12 articles from the selected issue
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Review
  • Kiyoshi NAGATA, Hiroyuki SUZUKI, Shuhei SAKAGUCHI
    Volume 32 (2007) Issue 5 Pages 453-468
    Released: January 16, 2008
    JOURNALS FREE ACCESS
    This review showed the common pathogenic mechanism in the development of non-alcoholic or alcoholic steatohepatitis. In particular, we describe the role of innate immune system and oxidative stress caused by gut-derived endotoxin. Gut-derived endotoxin plays an important role in alcoholic liver injury. It was reported that acute ethanol administration reduced activation of Kupffer cells. It is therefore possible that alcohol-induced hepatocellular damage occurs as a result of bacterial or endotoxin translocation under a reduction of the reticuloendothelial system (RES) function in alcoholic liver disease (ALD). On the other hand, recently, attention has been directed toward the effect of ethanol ingestion on Kupffer cell function, which is stimulated by gut-derived endotoxin via mechanisms dependent on increased gut permeability and the possible relationship between Kupffer cells and alcohol-induced liver injury. It is generally accepted that activation of the innate immune system and increased release of proinflammatory cytokines and other mediators plays an important role in the development of ALD. It was shown that Kupffer cells activation by endotoxin via Toll-like receptor (TLR-4) is involved in alcohol-induced liver injury and that ethanol-induced oxidative stress is important in the regulation of transcription factor NF-κB activation and that cytokine production by Kupffer cells. TNF-α and free radicals are produced in early alcohol-induced liver injury. In support of this finding, the pathology caused by alcohol was blocked nearly completely in TNF-α receptor 1. Many pathways have been suggested to contribute to the ability of ethanol to induce a state of oxidative stress. One central pathway appears to be the induction of the CYP2E1 form of cytochrome P450 enzymes by ethanol. Initial efforts to clarify the mechanisms that promote the progression from steatosis to steatohepatitis somewhat artificially divides disease mechanisms into "first and second" hit. The best candidates for these second hits were considered to be oxidative stress (CYP2E1 induction) and associated lipid peroxidation and cyokines, principally, TNF-α. Some of the most definitive data on the importance of the innate immune system or oxidative stress in the pathogenesis of liver disease come from studies of alcoholic and non-alcoholic steatohepatitis in animals.
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Original Article
  • Naoki KIYOSAWA, Takeki UEHARA, Weihua GAO, Ko OMURA, Mitsuhiro HIRODE, ...
    Volume 32 (2007) Issue 5 Pages 469-486
    Released: January 16, 2008
    JOURNALS FREE ACCESS
    To identify candidate biomarker gene sets to evaluate the potential risk of chemical-induced glutathione depletion in livers, we conducted microarray analysis on rat livers administered with phorone (40, 120 and 400 mg/kg), a prototypical glutathione depletor. Hepatic glutathione content was measured and glutathione depletion-responsive gene probe sets (GSH probe sets) were identified using Affymetrix Rat Genome 230 2.0 GeneChip by the following procedure. First, probe sets, whose signal values were inversely correlated with hepatic glutathione content throughout the experimental period, were statistically identified. Next, probe sets, whose average signal values were greater than 1.5-fold compared to those of controls 3 hr after phorone treatment, were selected. Finally, probe sets without unique Entrez Gene ID were removed, ending up with 161 probe sets in total. The usefulness of the identified GSH probe sets was verified by a toxicogenomics database. It was shown that signal profiles of the GSH probe sets in rats treated with bromobenzene were strongly altered compared with other chemicals. Focusing on bromobenzene, time-course profiles of hepatic glutathione content and gene expression revealed that the change in gene expression profile was marked after the bromobenzene treatment, whereas hepatic glutathione content had recovered after initial acute depletion, suggesting that the gene expression profile did not reflect the hepatic glutathione content itself, but rather reflects a perturbation of glutathione homeostasis. The identified GSH probe sets would be useful for detecting glutathione-depleting risk of chemicals from microarray data.
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  • Eric J. BUENZ, Brent A. BAUER, Timothy J. MOTLEY, Paul J. LIMBURG
    Volume 32 (2007) Issue 5 Pages 487-493
    Released: January 16, 2008
    JOURNALS FREE ACCESS
    During a recent botanical expedition in the Seychelles archipelago we identified healers using Diospyros seychellarum as a tonic. Since this plant lacks any medicinal record in the current literature, we assessed the cytotoxic potential of D. seychellarum. Using Jurkat cells as a model system we show, by flow cytometry, that treatment with the leaf extract results in mitochondrial depolarization and subsequent loss of cellular membrane integrity. Additionally, by transmission electron microscopy, we show that treatment with the extract results in chromatin condensation, mitochondrial swelling, and loss of nuclear membrane integrity. Through these morphological and biochemical observations we concluded that the extract of Diospyros seychellarum is able to induce apoptosis. While it is difficult to extrapolate a potential pharmacologic function based on the ethnomedical use as a tonic, the ability of this extract to induce apoptosis warrants further investigation of the medicinal properties of this plant.
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  • Ryohei YOKOI, Satoshi SUDA, Kazuo KOBAYASHI, Junji KURODA, Hiroshi KUS ...
    Volume 32 (2007) Issue 5 Pages 495-503
    Released: January 16, 2008
    JOURNALS FREE ACCESS
    The effects of exposure of pregnant rats to methyl methanesulfonate (MMS), an alkylating agent, during the pregastrulation period on embryonic and placental development were investigated. SD rats were treated orally with a single dose of MMS (200 mg/kg) in the morning of gestation days 0, 1, 2, 3, 4, 5, or 6 (GD0 to GD6 groups, respectively). The uterine contents including fetuses and placentas of the dams were examined on gestation day 20. The individual fetuses and placentas were weighed, and the fetuses were examined for external, visceral and skeletal anomalies. The progress of ossification was also evaluated. Both pre- and postimplantation embryonic mortalities were higher in the GD0 group than in the control group. The postimplantation loss was also increased for the GD3, GD4 and GD6 groups. Fetal malformations were rare in survivors of all the MMS-treated groups. Intrauterine growth retardation was apparent for fetuses in groups GD5 and GD6. In addition, placental weight was reduced in the GD6 group, but it was increased in the GD0 group. Effects of MMS on embryonic mortality or on fetal or placental growth were absent or minimal in the GD1 and GD2 groups. These results suggest that the susceptibility of rat embryos to MMS varies during the pregastrulation period.
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  • Wang ZHIPENG, Li MINGKAI, Cui SHUYU, Jia MIN, Meng JINGRU, Ma XUE, Wu ...
    Volume 32 (2007) Issue 5 Pages 505-514
    Released: January 16, 2008
    JOURNALS FREE ACCESS
    Potential toxicity of CoQ10 was studied in rats by oral gavage for 90 days at 500, 1500, and 3000 mg/kg·day. A 15-day recovery period after the administration period was investigated. Body weight and food consumption were measured throughout the study. Meanwhile, clinical observations were recorded. Hematological and blood chemistry parameters were evaluated at both the end of the dosing period and the end of the recovery period. Gross-pathologic and histopathologic examination was performed on select tissues from all animals. No adverse changes in mortality and clinical signs occurred. The body weights of males in the 1500 mg/kg dosage group were slightly reducted; likewise, the food consumption in 3000 mg/kg female rats decreased, but this is not a dose-dependent behavior. Significant change of liver function (TRIGL) and CHOL did not show a dose-dependent effect. Weight of ovary and ovary-to-body weight ratio decreased in the 1500 mg/kg dosage groups. Meanwhile, the uterus -to-body weight ratio increased the in 3000 mg/kg dosage groups. However, there were no significant histopathological changes observed in ovary and uterus: so they were not considered to be adverse. It suggested that CoQ10 is relatively safe on the test dosage administration. Nevertheless, appetite the body weight, blood lipid and liver function should be observed during long-term clinical administration of this drug with high dosage. Overall, CoQ10 was well tolerated by male and female rats at dose levels up to 3000 mg/kg·day.
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  • Toshinori YAMAMOTO, Ikuo HORII, Takemi YOSHIDA
    Volume 32 (2007) Issue 5 Pages 515-528
    Released: January 16, 2008
    JOURNALS FREE ACCESS
    High-resolution Magic Angle Spinning (Hr-MAS) 1H-NMR spectroscopy was used to analyze intact testicular tissues ex vivo and to investigate the toxicological effects of ethylene glycol monomethyl ether (EGME), a well-known spermatocytes toxicant, on male reproductive organs by NMR-based metabonomic analysis. Especially, we reported the first Hr-MAS 1H-NMR spectra of epididymis. Sexually matured male rats were treated with 50 and 2,000 mg/kg EGME, and body weight, reproductive organs weight, histopathology and plasma biochemistry were examined at 6 and 24 hr after administration. Two multivariate statistical methods, namely, unsupervised PCA and supervised PLS-DA, indicated that the balance of endogenous metabolites was perturbed in both reproductive organs and biofluids. In the testes, lactate, creatine and glutathione were mainly affected by EGME treatment. In urine and plasma, altered excretions of the TCA cycle intermediates (2-oxoglutarate, citrate and succinate) and the ketone-bodies (acetoacetate and β-hydroxybutyrate) were also observed. The finding in current integrated metabonomic analysis of both intact tissues and biofluids suggested that EGME-induced testicular toxicity was attributed to perturbation of the energy supply processes, suppression of the TCA cycle, or oxidative stress. Furthermore, Hr-MAS 1H-NMR proved useful to investigate the molecular snapshot of biological tissues and the mechanism of toxicity.
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  • Yoshihide SATOMI, Kazuko SAKAGUCHI, Yoshinori KASAHARA, Fumiaki AKAHOR ...
    Volume 32 (2007) Issue 5 Pages 529-553
    Released: January 16, 2008
    JOURNALS FREE ACCESS
    Although paraquat (PQ) is widely known to induce pulmonary fibrosis, the molecular mechanisms are poorly understood. Therefore, to bring a new dimension to the elucidation of the mechanisms, we conducted microarray experiments to investigate the expression profiles of 1,090 genes in the lungs during the progressive phase of PQ-induced pulmonary fibrosis in rats. After several s.c. injections of PQ, rats were divided into a fibrogenic group and a non-fibrogenic group. Time-course gene expression analysis of the fibrogenic group showed altered gene regulation throughout the experimental period. The expression levels of many cell membrane channel, transporter, and receptor genes were substantially altered. These genes were classified into two categories: polyamine transporter- and electrolyte/fluid balance-related genes. Moreover, comparative analysis of the fibrogenic and the non-fibrogenic group revealed 36 genes with significantly different patterns of expression, including the pro-apoptotic gene Bad. This indicates that Bad is a key factor in apoptosis and that apoptosis provides a major turning point in PQ-induced pulmonary fibrosis. Notably, subtypes of transforming growth factor (TGF)-β genes that are considered to play a pivotal role in fibrogenesis showed no differences in expression between the two groups, though TGF-β3 was markedly induced in both groups. These results provide novel and extensive insights into the molecular mechanisms that lead to pulmonary fibrosis after exposure to PQ.
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Letter
  • Yoshiko IKAWA, Taeko YONEKAWA, Yukie OHKUNI, Mariko KURIBAYASHI, Katsu ...
    Volume 32 (2007) Issue 5 Pages 555-564
    Released: January 16, 2008
    JOURNALS FREE ACCESS
    The effects of histamine and its receptor antagonists on mouse bone marrow cells (MBMC) and MC3T3-E1 cells were studied to elucidate the precise molecular mechanisms underlying histamine activities in the respective cell types. The studied parameters were osteoclast differentiation and expressions of receptor activator of nuclear factor κB ligand (RANKL), histamine receptors (HR), and osteoblast differentiation markers. The osteoclastogenesis was assessed by TRAP-dye method. Expressions of RANKL, HR and the osteoblast differentiation markers were evaluated by RT-PCR analysis. In MBMC, 1 μM histamine doubled the number of osteoclast-like cells in a dose-dependent manner. Expressions of RANKL peaked at histamine concentrations of 1 μM and 0.1 μM in MBMC and MC3T3-E1, respectively. H1R antagonist, but not H2R antagonist, inhibited RANKL expressions induced by histamine in MC3T3-E1. Histamine induced expressions of cell differentiation markers in MC3T3-E1, but not in MBMC, under the conditions that RANKL expressions were induced by histamine in both types of cells. These results indicate the following: (1) Histamine induction of osteoclastogenesis is mediated by RANKL expressed via H1R, but not via H2R in mouse osteoblast-like cells; (2) and the major target of histamine action is the RANKL-RANK signaling pathway in osteocytes. This observation is consistent with the traditionally recognized histamine action of bone resorption at the osteoclast site.
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  • Yasumoto MIZOGUCHI, Ema SANO, Ryo KAMATA, Tetsuya MATSUOKA, Yuzo ASANO
    Volume 32 (2007) Issue 5 Pages 565-570
    Released: January 16, 2008
    JOURNALS FREE ACCESS
    The purpose of the present investigation is to evaluate the restraining effects of protecting jackets attached from the pre-mating period and thereafter up to completion of the fetal organogenesis in rabbits. Forty (40) Kbl:NZW mated rabbits 6 to 10 months of age were divided into 2 groups of 20 animals each. Animals in the treatment group (hereinafter referred to as JK group) were dressed in protecting jackets from Day −9 prior to mating (hereinafter referred to as GD −9) to GD 19 and another group of animals without protecting jackets was used as a control. The major restraining effects noted were decreases in body weight gain and food consumption, which were marked in the first 9 days of jacket-attachment during the pre-mating period. The decrease in body weight was still apparent over the whole gestation period. However, the mean body weight of the JK group finally reached the baseline level of the study at around GD 11. These findings demonstrated that the restraining effects in the present study persisted longer than those in the previous study, in which protecting jackets were used from GD 0 to GD 19 or GD 6 to GD 19. The fertility function and cesarean section findings were comparable to those in the control group. It may be concluded that the use of protecting jackets from GD −9 to GD 19 induced more prolonged effects on body weight loss than in previous findings where the jackets were attached from GD 0 to GD 19 or GD 6 to GD 19 and the time of starting the acclimation with the jackets appears to play a great role in reducing body weight loss.
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  • Reiko TANAKA
    Volume 32 (2007) Issue 5 Pages 571-574
    Released: January 16, 2008
    JOURNALS FREE ACCESS
    The inhibitory effects of xanthone on genotoxicity induced by paraquat and NaNO2 in cultured Chinese hamster lung (CHL) cells were examined. Xanthone forms the central core of xanthones. Xanthones are present in mangosteen, which is widely used as health food because of its many pharmacological properties. Paraquat (PQ, a superoxide anion generator) and NaNO2 induce genotoxic effects, including sister chromatid exchange (SCE) and decreased cell cycle rate, in CHL cells. Xanthone inhibited the genotoxic effects of PQ and NaNO2 at concentrations of more than 5 μM. The present results suggested the potent antigenotoxic effects of xanthones in mangosteens.
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  • Shinya MAENOSONO, Toshimasa SUZUKI, Soichiro SAITA
    Volume 32 (2007) Issue 5 Pages 575-579
    Released: January 16, 2008
    JOURNALS FREE ACCESS
    A mutagenicity test was conducted on water-soluble FePt nanoparticles capped with tetramethylammonium hydroxide in a bacterial reverse mutation assay using Salmonella typhimurium strains TA98, TA100, TA1535 and TA1537, and Escherichia coli strain WP2uvrA/pKM101, with and without metabolic activation by S9 mix in the preincubation method. Mutagenicity was weakly positive in the TA100 strain without S9 mix (maximum specific activity was 61.6 revertants/mg), but negative in other cases.
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Toxicogenomics/proteomics Report
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