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  1. Article ; Online: Activation of PXR, CAR and PPARα by pyrethroid pesticides and the effect of metabolism by rat liver microsomes

    Chieri Fujino / Yoko Watanabe / Seigo Sanoh / Hiroyuki Nakajima / Naoto Uramaru / Hiroyuki Kojima / Kouichi Yoshinari / Shigeru Ohta / Shigeyuki Kitamura

    Heliyon, Vol 5, Iss 9, Pp e02466- (2019)

    2019  

    Abstract: In this study, we used reporter gene assays in COS-1 cells to examine the activation of rat pregnane X receptor (PXR), rat constitutive androstane receptor (CAR) and rat peroxisome-proliferator activated receptor (PPAR)α by pyrethroid pesticides, and to ... ...

    Abstract In this study, we used reporter gene assays in COS-1 cells to examine the activation of rat pregnane X receptor (PXR), rat constitutive androstane receptor (CAR) and rat peroxisome-proliferator activated receptor (PPAR)α by pyrethroid pesticides, and to understand the effects of metabolic modification on their activities. All eight pyrethroids tested in this study showed rat PXR agonistic activity; deltamethrin was the most potent, followed by cis-permethrin and cypermethrin. However, when the pyrethroids were incubated with rat liver microsomes, their rat PXR activities were decreased to various extents. Cis- and trans-permethrin showed weak rat CAR agonistic activity, while the other pyrethroids were inactive. However, fenvalerate showed dose-dependent inverse agonistic activity toward rat CAR, and this activity was reduced after metabolism. None of the pyrethroids showed rat PPARα agonistic activity, but a metabolite of cis-/trans-permethrin and phenothrin, 3-phenoxybenzoic acid, activated rat PPARα. Since PXR, CAR and PPARα regulate various xenobiotic/endobiotic-metabolizing enzymes, activation of these receptors by pyrethroids may result in endocrine disruption due to changes of hormone-metabolizing activities.
    Keywords Environmental health ; Environmental science ; Pesticide ; Toxicology ; CAR ; Liver microsomes ; Science (General) ; Q1-390 ; Social sciences (General) ; H1-99
    Subject code 571
    Language English
    Publishing date 2019-09-01T00:00:00Z
    Publisher Elsevier
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article: Profiling of bisphenol A and eight of its analogues on transcriptional activity via human nuclear receptors

    Kojima, Hiroyuki / Shinji Takeuchi / Seigo Sanoh / Katsuhiro Okuda / Shigeyuki Kitamura / Naoto Uramaru / Kazumi Sugihara / Kouichi Yoshinari

    Toxicology. 2019 Feb. 01, v. 413

    2019  

    Abstract: Several bisphenol A (BPA) analogues have been detected in environmental samples, foodstuffs, and/or human biological samples, and there is concern regarding their potential endocrine-disrupting effects. In this study, we characterized the agonistic and/ ... ...

    Abstract Several bisphenol A (BPA) analogues have been detected in environmental samples, foodstuffs, and/or human biological samples, and there is concern regarding their potential endocrine-disrupting effects. In this study, we characterized the agonistic and/or antagonistic activities of BPA and eight its analogues against human estrogen receptors (ERα/β), androgen receptor (AR), glucocorticoid receptor (GR), pregnane X receptor (PXR), and constitutive androstane receptor (CAR). All the test compounds, except for bisphenol P (BPP), showed both ERα and ERβ agonistic activities, with bisphenol AF (BPAF) being the most potent. On the other hand, BPAF and BPP showed ERα and ERβ antagonistic activities. Interestingly, their ER activities demonstrated a preference toward ERβ. All the test compounds, except for bisphenol S, showed AR antagonistic activities, with bisphenol E being the most potent. Weak GR antagonistic activities were also found in BPA and five its analogues. PXR agonistic activity was observed in the six compounds, with bisphenol Z being the most potent. Results of the CAR assay revealed that BPA and five its analogues acted as CAR inverse agonists. Taken together, these results suggested that BPA analogues demonstrate multiple effects via human nuclear receptors in a similar manner to BPA, and several analogues might have more potent endocrine-disrupting activity than does BPA.
    Keywords agonists ; androgen receptors ; androstanes ; bisphenol A ; bisphenol S ; estrogen receptors ; foods ; glucocorticoid receptors ; humans ; pregnanes ; transcription (genetics)
    Language English
    Dates of publication 2019-0201
    Size p. 48-55.
    Publishing place Elsevier B.V.
    Document type Article
    ZDB-ID 184557-3
    ISSN 1879-3185 ; 0300-483X
    ISSN (online) 1879-3185
    ISSN 0300-483X
    DOI 10.1016/j.tox.2018.12.001
    Database NAL-Catalogue (AGRICOLA)

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    In stock of ZB MED Cologne/Königswinter

    Zs.A 888: Show issues Location:
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  3. Article: Comparative study of hydrolytic metabolism of dimethyl phthalate, dibutyl phthalate and di(2-ethylhexyl) phthalate by microsomes of various rat tissues

    Ozaki, Hitomi / Kazumi Sugihara / Kyoko Moriguchi / Naoto Uramaru / Shigeru Ohta / Shigeyuki Kitamura / Tomomichi Sone / Yoko Watanabe

    Food and chemical toxicology. 2017 Feb., v. 100

    2017  

    Abstract: Phthalates are used in food packaging, and are transferred to foods as contaminants. In this study, we examined the hydrolytic metabolism of dimethyl phthalate (DMP), dibutyl phthalate (DBP) and di(2-ethylhexyl) phthalate (DEHP) by rat tissue microsomes. ...

    Abstract Phthalates are used in food packaging, and are transferred to foods as contaminants. In this study, we examined the hydrolytic metabolism of dimethyl phthalate (DMP), dibutyl phthalate (DBP) and di(2-ethylhexyl) phthalate (DEHP) by rat tissue microsomes. We found that carboxylesterase and lipase contribute differently to these activities. When DMP, DBP and DEHP were incubated with rat liver microsomes, DBP was most effectively hydrolyzed to the phthalate monoester, followed by DMP, and the activity toward DEHP was marginal. In contrast, small-intestinal microsomes exhibited relatively higher activity toward long-side-chain phthalates. Pancreatic microsomes showed high activity toward DEHP and DBP. Liver microsomal hydrolase activity toward DMP was markedly inhibited by bis(4-nitrophenyl)phosphate, and could be extracted with Triton X-100. The activity toward DBP and DEHP was partly inhibited by carboxylesterase inhibitor, and was partly solubilized with Triton X-100. Ces1e, Ces1d and Ces1f expressed in COS cells exhibited the highest hydrolase activity toward DBP, showing a similar pattern to that of liver microsomes. Ces1e showed activity towards DMP and DEHP. Pancreatic lipase also hydrolyzed DBP and DEHP. Thus, carboxylesterase and lipase contribute differently to phthalate hydrolysis: short-side-chain phthalates are mainly hydrolyzed by carboxylesterase and long-side-chain phthalates are mainly hydrolyzed by lipase.
    Keywords carboxylesterase ; dibutyl phthalate ; dimethyl phthalate ; food packaging ; foods ; hydrolysis ; liver ; liver microsomes ; metabolism ; octoxynol ; phosphates ; rats ; solubilization ; tissues ; toxicology ; triacylglycerol lipase
    Language English
    Dates of publication 2017-02
    Size p. 217-224.
    Publishing place Elsevier Ltd
    Document type Article
    ZDB-ID 782617-5
    ISSN 1873-6351 ; 0278-6915
    ISSN (online) 1873-6351
    ISSN 0278-6915
    DOI 10.1016/j.fct.2016.12.019
    Database NAL-Catalogue (AGRICOLA)

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    In stock of ZB MED Bonn / Germany

    Z 4035: Show issues

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  4. Article: Comparative study on transcriptional activity of 17 parabens mediated by estrogen receptor α and β and androgen receptor

    Watanabe, Yoko / Hiroyuki Kojima / Naoto Uramaru / Shigeru Ohta / Shigeyuki Kitamura / Shinji Takeuchi

    Food and chemical toxicology. 2013 July, v. 57

    2013  

    Abstract: The structure-activity relationships of parabens which are widely used as preservatives for transcriptional activities mediated by human estrogen receptor α (hERα), hERβ and androgen receptor (hAR) were investigated. Fourteen of 17 parabens exhibited ... ...

    Abstract The structure-activity relationships of parabens which are widely used as preservatives for transcriptional activities mediated by human estrogen receptor α (hERα), hERβ and androgen receptor (hAR) were investigated. Fourteen of 17 parabens exhibited hERα and/or hERβ agonistic activity at concentrations of ⩽1×10−5M, whereas none of the 17 parabens showed AR agonistic or antagonistic activity. Among 12 parabens with linear alkyl chains ranging in length from C1 to C12, heptylparaben (C7) and pentylparaben (C5) showed the most potent ERα and ERβ agonistic activity in the order of 10−7M and 10−8M, respectively, and the activities decreased in a stepwise manner as the alkyl chain was shortened to C1 or lengthened to C12. Most parabens showing estrogenic activity exhibited ERβ-agonistic activity at lower concentrations than those inducing ERα-agonistic activity. The estrogenic activity of butylparaben was markedly decreased by incubation with rat liver microsomes, and the decrease of activity was blocked by a carboxylesterase inhibitor. These results indicate that parabens are selective agonists for ERβ over ERα; their interactions with ERα/β are dependent on the size and bulkiness of the alkyl groups; and they are metabolized by carboxylesterases, leading to attenuation of their estrogenic activity.
    Keywords agonists ; androgen receptors ; carboxylesterase ; estrogen receptors ; estrogenic properties ; humans ; liver microsomes ; preservatives ; rats ; structure-activity relationships ; toxicology ; transcription (genetics)
    Language English
    Dates of publication 2013-07
    Size p. 227-234.
    Publishing place Elsevier Ltd
    Document type Article
    ZDB-ID 782617-5
    ISSN 1873-6351 ; 0278-6915
    ISSN (online) 1873-6351
    ISSN 0278-6915
    DOI 10.1016/j.fct.2013.03.036
    Database NAL-Catalogue (AGRICOLA)

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    In stock of ZB MED Bonn / Germany

    Z 4035: Show issues

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