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Iwashita K, Hosokawa Y, Ihara R, Miyamoto T, Otani M, Abe J, Asano K, Mercier O, Miyata K, Barlow S. Flumioxazin, a PPO inhibitor: A weight-of-evidence consideration of its mode of action as a developmental toxicant in the rat and its relevance to humans. Toxicology 2022; 472:153160. [DOI: 10.1016/j.tox.2022.153160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Revised: 03/15/2022] [Accepted: 03/17/2022] [Indexed: 10/18/2022]
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Asano K, Takahashi Y, Ueno M, Fukuda T, Otani M, Kitamoto S, Tomigahara Y. Lack of human relevance for rat developmental toxicity of flumioxazin is revealed by comparative heme synthesis assay using embryonic erythroid cells derived from human and rat pluripotent stem cells. J Toxicol Sci 2022; 47:125-138. [DOI: 10.2131/jts.47.125] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- Koji Asano
- Environmental Health Science Laboratory, Sumitomo Chemical Co., Ltd
| | | | - Manako Ueno
- Bioscience Research Laboratory, Sumitomo Chemical Co., Ltd
| | - Takako Fukuda
- Bioscience Research Laboratory, Sumitomo Chemical Co., Ltd
| | - Mitsuhiro Otani
- Environmental Health Science Laboratory, Sumitomo Chemical Co., Ltd
| | - Sachiko Kitamoto
- Environmental Health Science Laboratory, Sumitomo Chemical Co., Ltd
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Halder S, Kar R, Chakraborty S, Banerjee BD. Chromium Exposure in Late Gestation Period Caused Increased Levels of Cr in Brain Tissue: Association with Alteration of Activity and Gene Expression of Antioxidant Enzymes of F1 and F2 Generation Mice. Biol Trace Elem Res 2021; 199:2635-2643. [PMID: 32892319 DOI: 10.1007/s12011-020-02367-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 09/01/2020] [Indexed: 11/28/2022]
Abstract
Chromium is a micronutrient which has found frequent use as supplements during pregnancy and could have a role in altering the antioxidant status in the brain. The present study was undertaken to estimate chromium levels in the brain, antioxidant enzyme activity with their gene expression, and learning and memory parameters on F1 and F2 generation mice when the F0 was exposed to chromium. The chromium levels in the brain were estimated using atomic absorption spectrophotometer. The enzyme activity of glutathione-s-transferase (GST) and catalase (CAT) was estimated and their gene expression was evaluated using RT-PCR. The spatial memory was tested using Morris water maze. The learning and recall memory was tested using the step down latency paradigm. The chromium levels were significantly raised in animals treated with Cr per se in F1 generation and quercetin cotreatment reduced the Cr levels in brain significantly. The enzyme activity of GST was significantly less in Cr-treated animals of both generations and this effect was significantly reversed on cotreatment with quercetin. The gene expression of GST matched the enzyme activity. However, catalase activity did not show significant decrease with Cr but cotreatment with quercetin resulted in significant decrease compared with control and this effect was not matched by its gene expression. We observed no significant change in learning and memory parameters in both generations following Cr exposure. Thus, this study demonstrates that chromium exposure in gestation causes changes in enzyme activity especially GST and this change was matched by change in gene expression in GST but not CAT. There was no effect on memory at the given dose.
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Affiliation(s)
- Sumita Halder
- Department of Pharmacology, University College of Medical Sciences and G. T. B. Hospital, New Delhi, 110095, India.
| | - Rajarshi Kar
- Department of Biochemistry, University College of Medical Sciences and G. T. B. Hospital, New Delhi, 110095, India
| | - Sucharita Chakraborty
- Geological Oceanographic Division, National Institute of Oceanograhy, Panaji, Goa, India
- Department of Geology and Geophysics, Indian Institute of Technology, Kharagpur, India
| | - Basu D Banerjee
- Department of Biochemistry, University College of Medical Sciences and G. T. B. Hospital, New Delhi, 110095, India
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Kawamura S, Otani M, Miyamoto T, Abe J, Ihara R, Inawaka K, Fantel AG. Different effects of an N-phenylimide herbicide on heme biosynthesis between human and rat erythroid cells. Reprod Toxicol 2021; 99:27-38. [PMID: 33249232 DOI: 10.1016/j.reprotox.2020.11.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 10/28/2020] [Accepted: 11/22/2020] [Indexed: 01/10/2023]
Abstract
Rat developmental toxicity including embryolethality and teratogenicity (mainly ventricular septal defects and wavy ribs) were produced by S-53482, an N-phenylimide herbicide that inhibits protoporphyrinogen oxidase (PPO) common to chlorophyll and heme biosynthesis. The sequence of key biological events in the mode of action has been elucidated as follows: inhibition of PPO interferes with normal heme synthesis, which causes loss of blood cells leading to fetal anemia, embryolethality and the development of malformations. In this study we investigated whether the rat is a relevant model for the assessment of the human hazard of the herbicide. To study effects on heme biosynthesis, human erythroleukemia, human cord blood, and rat erythroleukemia cells were treated with the herbicide during red cell differentiation. Protoporphyrin IX, a marker of PPO inhibition, and heme were determined. We investigated whether synchronous maturation of primitive erythropoiesis, which can contribute to massive losses of embryonic blood, occurs in rats. The population of primitive erythroblasts was observed on gestational days 11 through 14. Heme production was suppressed in rat erythroid cells. In contrast, heme reduction was not seen in both human erythroid cells when PPO was inhibited. Rats underwent synchronous maturation in primitive erythropoiesis. Our results combined with epidemiological findings that patients with deficient PPO are not anemic led us to conclude that human erythroblasts are resistant to the herbicide. It is suggested that the rat would be an inappropriate model for assessing the developmental toxicity of S-53482 in humans as rats are specifically sensitive to PPO inhibition by the herbicide.
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Affiliation(s)
- Satoshi Kawamura
- Environmental Health Science Laboratory, Sumitomo Chemical Co., Ltd., 1-98, Kasugade-naka 3-chome, Konohana-ku, Osaka, 554-8558, Japan.
| | - Mitsuhiro Otani
- Environmental Health Science Laboratory, Sumitomo Chemical Co., Ltd., 1-98, Kasugade-naka 3-chome, Konohana-ku, Osaka, 554-8558, Japan
| | - Taiki Miyamoto
- Environmental Health Science Laboratory, Sumitomo Chemical Co., Ltd., 1-98, Kasugade-naka 3-chome, Konohana-ku, Osaka, 554-8558, Japan
| | - Jun Abe
- Environmental Health Science Laboratory, Sumitomo Chemical Co., Ltd., 1-98, Kasugade-naka 3-chome, Konohana-ku, Osaka, 554-8558, Japan
| | - Ryo Ihara
- Environmental Health Science Laboratory, Sumitomo Chemical Co., Ltd., 1-98, Kasugade-naka 3-chome, Konohana-ku, Osaka, 554-8558, Japan
| | - Kunifumi Inawaka
- Environmental Health Science Laboratory, Sumitomo Chemical Co., Ltd., 1-98, Kasugade-naka 3-chome, Konohana-ku, Osaka, 554-8558, Japan
| | - Alan G Fantel
- Department of Pediatrics, University of Washington, 1959 NE Pacific St. Box 366320, Seattle, WA 98195-6320, USA
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Abe J, Isobe N, Mikata K, Nagahori H, Naito Y, Saji H, Ono M, Kawamura S. Flumioxazin metabolism in pregnant animals and cell-based protoporphyrinogen IX oxidase (PPO) inhibition assay of fetal metabolites in various animal species to elucidate the mechanism of the rat-specific developmental toxicity. Toxicol Appl Pharmacol 2017; 339:34-41. [PMID: 29198728 DOI: 10.1016/j.taap.2017.11.028] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Revised: 11/28/2017] [Accepted: 11/29/2017] [Indexed: 02/02/2023]
Abstract
Flumioxazin, an N-phenylimide herbicide, inhibits protoporphyrinogen oxidase (PPO), a key enzyme in heme biosynthesis in mammals, and causes rat-specific developmental toxicity. The mechanism has mainly been clarified, but no research has yet focused on the contribution of its metabolites. We therefore conducted in vivo metabolism studies in pregnant rats and rabbits, and found 6 major known metabolites in excreta. There was no major rat-specific metabolite. The most abundant component in rat fetuses was APF, followed by flumioxazin and 5 identified metabolites. The concentrations of flumioxazin and these metabolites in fetuses were lower in rabbits than in rats. In vitro PPO inhibition assays with rat and human liver mitochondria showed that flumioxazin is a more potent PPO inhibitor than the metabolites. There were no species differences in relative intensity of PPO inhibition among flumioxazin and these metabolites. Based on the results of these in vivo and in vitro experiments, we concluded that flumioxazin is the causal substance of the rat-specific developmental toxicity. As a more reliable test system for research on in vitro PPO inhibition, cell-based assays with rat, rabbit, monkey, and human hepatocytes were performed. The results were consistent with those of the mitochondrial assays, and rats were more sensitive to PPO inhibition by flumioxazin than humans, while rabbits and monkeys were almost insensitive. From these results, the species difference in the developmental toxicity was concluded to be due to the difference in sensitivity of PPO to flumioxazin, and rats were confirmed to be the most sensitive of these species.
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Affiliation(s)
- Jun Abe
- Environmental Health Science Laboratory, Sumitomo Chemical Co., Ltd., 1-98, 3-Chome, Kasugade-Naka, Konohana-Ku, Osaka 554-8558, Japan.
| | - Naohiko Isobe
- Environmental Health Science Laboratory, Sumitomo Chemical Co., Ltd., 1-98, 3-Chome, Kasugade-Naka, Konohana-Ku, Osaka 554-8558, Japan
| | - Kazuki Mikata
- Environmental Health Science Laboratory, Sumitomo Chemical Co., Ltd., 1-98, 3-Chome, Kasugade-Naka, Konohana-Ku, Osaka 554-8558, Japan
| | - Hirohisa Nagahori
- Environmental Health Science Laboratory, Sumitomo Chemical Co., Ltd., 1-98, 3-Chome, Kasugade-Naka, Konohana-Ku, Osaka 554-8558, Japan
| | - Yoshikazu Naito
- Environmental Health Science Laboratory, Sumitomo Chemical Co., Ltd., 1-98, 3-Chome, Kasugade-Naka, Konohana-Ku, Osaka 554-8558, Japan
| | - Hideo Saji
- Department of Patho-Functional Bioanalysis, Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29, Yoshida Shimoadachi-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Masahiro Ono
- Department of Patho-Functional Bioanalysis, Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29, Yoshida Shimoadachi-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Satoshi Kawamura
- Environmental Health Science Laboratory, Sumitomo Chemical Co., Ltd., 1-98, 3-Chome, Kasugade-Naka, Konohana-Ku, Osaka 554-8558, Japan
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