The Journal of Toxicological Sciences
Online ISSN : 1880-3989
Print ISSN : 0388-1350
ISSN-L : 0388-1350
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Original Article
  • Tomoaki Tochitani, Akihito Yamashita, Izumi Matsumoto, Mami Kouchi, Yu ...
    2019 Volume 44 Issue 9 Pages 575-584
    Published: 2019
    Released: September 02, 2019
    JOURNALS FREE ACCESS FULL-TEXT HTML

    The adrenal gland is the most common toxicological target of drugs within the endocrine system, and inhibition of adrenal steroidogenesis can be fatal in humans. However, methods to evaluate the adrenal toxicity are limited. The aim of the present study was to verify the usefulness of simultaneous measurement of blood levels of multiple adrenal steroids, including precursors, as a method to evaluate drug effects on adrenal steroidogenesis in cynomolgus monkeys. With this aim, physiological and drug-induced changes in blood levels of adrenal steroids, including cortisol, aldosterone, androgen, and their precursors were examined. First, for physiological changes, intraday and interday changes in blood steroid levels were examined in male and female cynomolgus monkeys. The animals showed circadian changes in steroid levels that are similar to those in humans, while interday changes were relatively small in males. Next, using males, changes in blood steroid levels induced by ketoconazole and metyrapone were examined, which suppress adrenal steroidogenesis via inhibition of CYP enzymes. Consistent with rats and humans, both ketoconazole and metyrapone increased the deoxycorticosterone and deoxycortisol levels, probably via CYP11B1 inhibition, and the increase was observed earlier and with greater dynamic range than the changes in cortisol level. Changes in other steroid levels reflecting the drug mechanisms were also observed. In conclusion, this study showed that in cynomolgus monkeys, simultaneous measurement of blood levels of adrenal steroids, including precursors, can be a valuable method to sensitively evaluate drug effects on adrenal steroidogenesis and to investigate the underlying mechanisms.

Original Article
  • Yusuke Yamamoto, Masaharu Fujita, Sayaka Wanibuchi, Ayako Sato, Miyuki ...
    2019 Volume 44 Issue 9 Pages 585-600
    Published: 2019
    Released: September 02, 2019
    JOURNALS FREE ACCESS FULL-TEXT HTML

    Amino acid derivative reactivity assay (ADRA) has previously been developed as an alternative method to direct peptide reactivity assay (DPRA) to evaluate key event 1 in skin sensitization mechanisms. However, when using alternative methods for skin sensitization, integrated approaches to testing and assessment (IATA) that combine the results of multiple tests evaluating different key events are generally required. To verify whether ADRA can be used in IATA, we replaced DPRA with ADRA in five IATA methods combining DPRA, KeratinoSens, and h-CLAT: (i) the “2 out of 3” approach, (ii) the “3 out of 3” approach, (iii) sequential testing strategy (STS), (iv) integrated testing strategy by scoring approach (ITS-SA), and (v) the “ITS by two methods approach” (ITS-2MA). The prediction accuracy of the “2 out of 3” approach using ADRA (1 mM) and ADRA (0.5 mg/mL) was 90.0% and 91.1%, respectively, for human data, and was very similar to that obtained using DPRA (91.1%). The “3 out of 3” approach also showed good predictability (83.2%) using either ADRA (1 mM) or ADRA (0.5 mg/mL) compared to DPRA. Regarding the accuracy of the prediction of sensitization intensity for the human data by the third classification, prediction accuracy using ADRA was almost the same as STS, ITS-SA, or ITS-2MA using DPRA. As a result, this study showed that ADRA can be used as a test method for key event 1 in the evaluation of skin sensitization by combining multiple alternative methods.

Original Article
  • Tomoaki Tochitani, Akihito Yamashita, Izumi Matsumoto, Mami Kouchi, Yu ...
    2019 Volume 44 Issue 9 Pages 601-610
    Published: 2019
    Released: September 02, 2019
    JOURNALS FREE ACCESS FULL-TEXT HTML

    To verify simultaneous measurement of blood levels of adrenal steroids as a tool to evaluate drug effects on adrenal steroidogenesis, dose- and time-dependent changes in blood levels of corticosterone and its precursors (pregnenolone, progesterone and deoxycorticosterone), as well as their relationship with the pathological changes in the adrenal gland, were examined in rats dosed with ketoconazole (KET). Also examined were whether effects on adrenal steroidogenesis that were not obvious in the blood steroid levels after sole administration of KET could be revealed by post-administration of ACTH, and the correlation between the blood and adrenal steroid levels. Male rats were dosed with 15, 50, or 150 mg/kg of KET for 1 or 7 days with or without ACTH, and the blood and adrenal concentrations of the steroids were measured. KET increased the blood deoxycorticosterone level even at a dose level and time point at which histopathological changes were not obvious. KET-induced changes in blood levels of other steroids were revealed by ACTH, and the blood and adrenal levels were generally correlated especially after ACTH post-administration. Thus, blood levels of adrenal steroids, including precursors, can be a sensitive and early marker of drug effects on the adrenal steroidogenesis that reflect adrenal levels of steroids. The usefulness of the multiple steroid measurement as a method for mechanism investigation of drug effects on the adrenal gland can be further enhanced by ACTH.

Original Article
  • Hitomi Fujishiro, Satoko Hamao, Misaki Isawa, Seiichiro Himeno
    2019 Volume 44 Issue 9 Pages 611-619
    Published: 2019
    Released: September 02, 2019
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    The kidney proximal tubule is a target of many renal toxicants, including cadmium (Cd), and also a place of reabsorption of essential metals in glomerular filtrate to systemic circulation. Although the mechanisms of metal transport in the convoluted proximal tubule (S1 and S2 segments) and the straight proximal tubule (S3 segment) may differ, little is known about the segment-specific modes of metal transport. Here, we utilized immortalized cell lines derived from the S1, S2, and S3 segments of mouse kidney proximal tubules, and examined the segment-specific and direction-dependent transport of Cd and manganese (Mn) using a trans-well culture system. The results showed that the uptakes of Cd2+ and Mn2+ from apical sides were the highest in S3 cells, and Cd2+, Mn2+, and Zn2+ mutually inhibited the apical uptake of each metal. As the expression of ZIP8, a zinc transporter having affinities for Cd2+ and Mn2+, was the highest in S3 cells, ZIP8 may contribute largely to the apical uptakes of these metals. The efficient uptake of Mn2+ from apical side of S3 cells may suggest an important role of ZIP8 in proximal tubule in reabsorption of Mn, an essential metal. Our study demonstrated that S1, S2, and S3 cells provide a useful tool for studying the segment-specific and direction-dependent transport of both toxic and essential metals in the kidney’s proximal tubules.

Original Article
  • Yuan Chen, Xiaoxiao Fei, Chenqiao Ye, Qinqing Qian, Zhiqiu Ye, Siqi Xi ...
    2019 Volume 44 Issue 9 Pages 621-632
    Published: 2019
    Released: September 02, 2019
    JOURNALS FREE ACCESS FULL-TEXT HTML

    In the past few decades, upconversion nanoparticles (abbreviated as UCNPs) have been more widely applied in the biomedical fields, such as in vitro and in vivo upconversion fluorescent bioimaging, photodynamic therapy, biological macromolecular detection, imaging mediated drug delivery and so on. But meanwhile, there is still not much research on the acute toxicity of upconversion nanoparticles in vivo, such as acute hepatotoxicity. In this work, we studied the in vivo biodistribution and acute hepatotoxicity of multimodal targeted contrast agent NaLuF4:Gd,Yb,Er-PEG/PEI-FA nanoprobe, which were synthesized by the solvothermal method and modified with Polyethylene glycol (PEG), Polyetherimide (PEI), folic acid (FA) on the surface. The acute hepatotoxicity in mice was systematically assessed after tail vein injection of different concentration of UCNPs. The results showed that NaLuF4:Gd,Yb,Er-PEG/PEI-FA nanoparticles with an average diameter of 44.5 ± 10.4 nm, and three typical upconversion fluorescence emission bands at 520 nm, 540 nm and 660 nm under the excitation of 980 nm laser. In vivo distribution experiments results demonstrated that approximately 87% of UCNPs injected through the tail vein accumulate in the liver. In the acute hepatotoxicity test, the intravenously injection dose of UCNPs was 10, 40, 70 and 100 mg/kg, respectively. The body weight, blood routine, serum biochemistry, histomorphology and liver oxidative stress were detected and observed no significant acute hepatotoxicity damage under the injection dose of 100 mg/kg. In conclusion, NaLuF4:Gd,Yb,Er-PEG/PEI-FA nanoprobes are safe and reliable, and have potential applications in the field of tumor targeted multimodal imaging.

Original Article
  • Yong Hyun Lee, Dae Young Kim, Sung Hwan Jeong, You Jin Hwang
    2019 Volume 44 Issue 9 Pages 633-641
    Published: 2019
    Released: September 02, 2019
    JOURNALS FREE ACCESS FULL-TEXT HTML

    Asian Sand Dust-Particulate Matter (ASD-PM) aerosol brings large amounts of wind-eroded soil particles containing high concentrations of metallic components caused by industrialization and vehicles. Proinflammatory and cytotoxic cytokines trigger local inflammatory responses and cause a systematically high incidence of cardiovascular and other diseases. Tenascin C (Tn-C) is known to be expressed in damaged tissue or in a developmental stage of tissue. In this study, we examined the expression of Tn-C and Fibronectin in human cancer-cell lines and in liver tissue of mice treated with ASD-PM to investigate the inflammatory and cell-damage effects of ASD-PM. In our in vivo study, mice were intratracheally instilled with saline suspensions of ASD-PM particles. Instillation of these particles was repeated twice a week for 12 weeks and the liver tissues were stained with hematoxylin, eosin, and Masson’s trichrome, and we carried out an IF. Tn-C expression in liver tissues was detected by RT-PCR and western blot analysis. In the results, the expression of Tn-C increased in a dose-dependent manner in both RNA and Immunofluorescence assay (IF). In our in vitro study, A549 and Hep3B cell lines were incubated in culture media with Transforming Growth Factor-Beta1(TGF-β1) and ASD-PM. Immunofluorescence microscopy images showed a two times stronger expression of fluorescence in the ASD-treated group than in that treated with TGF-β1. They also showed a stronger expression of Tn-C in proportion to the concentration of ASD-PM. We confirmed that ASD-PM when inhaled formally migrated to other organs and induced Tn-C expression. ASD-PM containing metals causes expression of Tn-C in liver tissue in proportion to the concentration of ASD-PM.

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