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Earl Gray L. Biologically relevant reductions in fetal testosterone and Insl3 induced by in utero exposure to high levels of di-isononyl phthalate (DINP) in male rats. Toxicol Appl Pharmacol 2023; 465:116454. [PMID: 36921846 PMCID: PMC10405973 DOI: 10.1016/j.taap.2023.116454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Revised: 03/02/2023] [Accepted: 03/04/2023] [Indexed: 03/16/2023]
Abstract
Some phthalate esters alter male rat reproductive development during sexual differentiation by interfering with fetal testis maturation resulting in reduced Leydig Cell synthesis of testosterone and insulin-like 3 (Insl3) hormones. Gene transcripts associated with steroid hormone and cholesterol transport, and cholesterol synthesis and lipid metabolism also are reduced. These alterations cause permanent malformations of hormone-dependent tissues, sperm production and fertility in male offspring; effects known as the "Phthalate Syndrome." We have shown that administration of a high dose of 750 mg diisononyl phthalate (750 mg/kg/d DINP) during sex differentiation reduced fetal testis testosterone production (T Prod), testis gene expression and induced a low incidence of reproductive malformations in male rat offspring. In the current study we administered DINP at even higher dose levels (1.0 and 1.5 g/kg/d) from gestational day (GD) 14 to postnatal (PND) 3 to determine if these effects were dose related and if the magnitude of the effects could be predicted from a statistical model of fetal testosterone production (T Prod) and Insl3 mRNA levels. These models were previously developed using dipentyl phthalate (DPeP) data from fetal T Prod and postnatal studies. We found that the severity of the demasculinizing effects on the androgen-dependent organs and gubernaculum by DINP were accurately predicted from the statistical models of fetal T prod and Insl3 mRNA, respectively. Taken together, our results indicate that reductions fetal T prod and Insl3 predict the severity of demasculinizing effects in utero exposure to the phthalates DINP and DPeP regardless of potency.
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Affiliation(s)
- L Earl Gray
- Reproductive And Developmental Toxicology Branch, PHITD, CPHEA, Office of Research and Development, US Environmental Protection Agency, Research Triangle Park, Mail Drop-72, NC 27711, United States of America.
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Garcia A, Gaju O, Bowerman AF, Buck SA, Evans JR, Furbank RT, Gilliham M, Millar AH, Pogson BJ, Reynolds MP, Ruan Y, Taylor NL, Tyerman SD, Atkin OK. Enhancing crop yields through improvements in the efficiency of photosynthesis and respiration. New Phytol 2023; 237:60-77. [PMID: 36251512 PMCID: PMC10100352 DOI: 10.1111/nph.18545] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Accepted: 09/15/2022] [Indexed: 06/06/2023]
Abstract
The rate with which crop yields per hectare increase each year is plateauing at the same time that human population growth and other factors increase food demand. Increasing yield potential (Y p ) of crops is vital to address these challenges. In this review, we explore a component ofY p that has yet to be optimised - that being improvements in the efficiency with which light energy is converted into biomass (ε c ) via modifications to CO2 fixed per unit quantum of light (α), efficiency of respiratory ATP production (ε prod ) and efficiency of ATP use (ε use ). For α, targets include changes in photoprotective machinery, ribulose bisphosphate carboxylase/oxygenase kinetics and photorespiratory pathways. There is also potential forε prod to be increased via targeted changes to the expression of the alternative oxidase and mitochondrial uncoupling pathways. Similarly, there are possibilities to improveε use via changes to the ATP costs of phloem loading, nutrient uptake, futile cycles and/or protein/membrane turnover. Recently developed high-throughput measurements of respiration can serve as a proxy for the cumulative energy cost of these processes. There are thus exciting opportunities to use our growing knowledge of factors influencing the efficiency of photosynthesis and respiration to create a step-change in yield potential of globally important crops.
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Affiliation(s)
- Andres Garcia
- ARC Centre of Excellence in Plant Energy Biology, Research School of BiologyThe Australian National UniversityCanberraACT2601Australia
- Division of Plant Sciences, Research School of BiologyAustralian National UniversityCanberraACT2601Australia
| | - Oorbessy Gaju
- ARC Centre of Excellence in Plant Energy Biology, Research School of BiologyThe Australian National UniversityCanberraACT2601Australia
- College of Science, Lincoln Institute for Agri‐Food TechnologyUniversity of LincolnLincolnshireLN2 2LGUK
| | - Andrew F. Bowerman
- ARC Centre of Excellence in Plant Energy Biology, Research School of BiologyThe Australian National UniversityCanberraACT2601Australia
- Division of Plant Sciences, Research School of BiologyAustralian National UniversityCanberraACT2601Australia
| | - Sally A. Buck
- ARC Centre of Excellence in Plant Energy Biology, Research School of BiologyThe Australian National UniversityCanberraACT2601Australia
- Division of Plant Sciences, Research School of BiologyAustralian National UniversityCanberraACT2601Australia
| | - John R. Evans
- Division of Plant Sciences, Research School of BiologyAustralian National UniversityCanberraACT2601Australia
- ARC Centre of Excellence for Translational Photosynthesis, Research School of BiologyThe Australian National UniversityCanberraACT2601Australia
| | - Robert T. Furbank
- Division of Plant Sciences, Research School of BiologyAustralian National UniversityCanberraACT2601Australia
- ARC Centre of Excellence for Translational Photosynthesis, Research School of BiologyThe Australian National UniversityCanberraACT2601Australia
| | - Matthew Gilliham
- ARC Centre of Excellence in Plant Energy Biology, School of Agriculture, Food and Wine & Waite Research InstituteUniversity of AdelaideGlen OsmondSA5064Australia
| | - A. Harvey Millar
- ARC Centre of Excellence in Plant Energy Biology, School of Molecular Sciences & Institute of AgricultureThe University of Western AustraliaCrawleyWA6009Australia
| | - Barry J. Pogson
- ARC Centre of Excellence in Plant Energy Biology, Research School of BiologyThe Australian National UniversityCanberraACT2601Australia
- Division of Plant Sciences, Research School of BiologyAustralian National UniversityCanberraACT2601Australia
| | - Matthew P. Reynolds
- International Maize and Wheat Improvement Center (CIMMYT)Km. 45, Carretera Mexico, El BatanTexcoco56237Mexico
| | - Yong‐Ling Ruan
- Division of Plant Sciences, Research School of BiologyAustralian National UniversityCanberraACT2601Australia
| | - Nicolas L. Taylor
- ARC Centre of Excellence in Plant Energy Biology, School of Molecular Sciences & Institute of AgricultureThe University of Western AustraliaCrawleyWA6009Australia
| | - Stephen D. Tyerman
- ARC Centre of Excellence in Plant Energy Biology, School of Agriculture, Food and Wine & Waite Research InstituteUniversity of AdelaideGlen OsmondSA5064Australia
| | - Owen K. Atkin
- ARC Centre of Excellence in Plant Energy Biology, Research School of BiologyThe Australian National UniversityCanberraACT2601Australia
- Division of Plant Sciences, Research School of BiologyAustralian National UniversityCanberraACT2601Australia
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3
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Ito T, Miwa C, Haga Y, Kubo M, Itoh T, Yamamoto K, Mise S, Goto E, Tsuzuki H, Matsumura C, Nakano T, Inui H. Enantioselective metabolism of chiral polychlorinated biphenyl 2,2',3,4,4',5',6-Heptachlorobiphenyl (CB183) by human and rat CYP2B subfamilies. Chemosphere 2022; 308:136349. [PMID: 36084836 DOI: 10.1016/j.chemosphere.2022.136349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2022] [Revised: 08/10/2022] [Accepted: 09/02/2022] [Indexed: 06/15/2023]
Abstract
Chiral polychlorinated biphenyls (PCBs) have atropisomers that have different axial chiralities and exist as racemic mixtures. However, biochemical processes often result in the unequal accumulation of these atropisomers in organisms. This phenomenon leads to enantiospecific toxicity enhancement or reduction because either of the atropisomers mainly affects toxicity expression. Enantioselective accumulation is caused by cytochrome P450 (CYP, P450) monooxygenases, especially the CYP2B subfamilies. Therefore, this study investigates the metabolism of a chiral PCB in vitro. Both atropisomers isolated from racemic 2,2',3,4,4',5',6-heptachlorobiphenyl (CB183) were metabolized by human CYP2B6, but not rat CYP2B1. This may be due to the difference in the size of the substrate-binding cavities of CYP2B6 and CYP2B1. The stable accommodation of (-)-CB183 in the cavity without any steric hindrance explained the preferential metabolism of (-)-CB183 compared to (+)-CB183. Two hydroxylated metabolites, 3'-OH-CB183 and 5-OH-CB183, were identified. The docking study showed that the 3'-position of the trichlorophenyl ring closely approaches the heme of CYP2B6. To our knowledge, this is the first study to elucidate the structural basis of chiral PCB metabolism by P450 isozymes. These results will help promote the precise toxicity evaluation of chiral PCBs and provide an explanation of the structural basis of chiral PCB metabolism.
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Affiliation(s)
- Terushi Ito
- Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodaicho, Nada-ku, Kobe, Hyogo, 657-8501, Japan
| | - Chiharu Miwa
- Faculty of Agriculture, Kobe University, 1-1 Rokkodaicho, Nada-ku, Kobe, Hyogo, 657-8501, Japan
| | - Yuki Haga
- Hyogo Prefectural Institute of Environmental Sciences, 3-1-18 Yukihiracho, Suma-ku, Kobe, Hyogo, 654-0037, Japan
| | - Makoto Kubo
- Laboratory of Drug Design and Medicinal Chemistry, Showa Pharmaceutical University, 3-3165 Higashi-Tamagawagakuen, Machida, Tokyo, 194-8543, Japan
| | - Toshimasa Itoh
- Laboratory of Drug Design and Medicinal Chemistry, Showa Pharmaceutical University, 3-3165 Higashi-Tamagawagakuen, Machida, Tokyo, 194-8543, Japan
| | - Keiko Yamamoto
- Laboratory of Drug Design and Medicinal Chemistry, Showa Pharmaceutical University, 3-3165 Higashi-Tamagawagakuen, Machida, Tokyo, 194-8543, Japan
| | - Shintaro Mise
- Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodaicho, Nada-ku, Kobe, Hyogo, 657-8501, Japan
| | - Erika Goto
- Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodaicho, Nada-ku, Kobe, Hyogo, 657-8501, Japan
| | - Harunobu Tsuzuki
- Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodaicho, Nada-ku, Kobe, Hyogo, 657-8501, Japan
| | - Chisato Matsumura
- Hyogo Prefectural Institute of Environmental Sciences, 3-1-18 Yukihiracho, Suma-ku, Kobe, Hyogo, 654-0037, Japan
| | - Takeshi Nakano
- Research Center for Environmental Preservation, Osaka University, 2-4 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Hideyuki Inui
- Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodaicho, Nada-ku, Kobe, Hyogo, 657-8501, Japan; Biosignal Research Center, Kobe University, 1-1 Rokkodaicho, Nada-ku, Kobe, Hyogo, 657-8501, Japan.
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Inui H, Ito T, Miwa C, Haga Y, Kubo M, Itoh T, Yamamoto K, Miyaoka M, Mori T, Tsuzuki H, Mise S, Goto E, Matsumura C, Nakano T. Differences in Enantioselective Hydroxylation of 2,2',3,6-Tetrachlorobiphenyl (CB45) and 2,2',3,4',6-Pentachlorobiphenyl (CB91) by Human and Rat CYP2B Subfamilies. Environ Sci Technol 2022; 56:10204-10215. [PMID: 35801261 DOI: 10.1021/acs.est.2c01155] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Although polychlorinated biphenyls (PCBs) were commercially banned half a century ago, contamination of the environment and organisms by PCBs is still observed. PCBs show high persistence and bioaccumulation, resulting in toxicity. Among PCBs, chiral PCBs with more than three chlorine atoms at the ortho-position exhibit developmental and neurodevelopmental toxicity. Because toxicity is dependent on the atropisomer, atropisomer-specific metabolism is vital in determining toxicity. However, structural information on enantioselective metabolism remains elusive. Cytochrome P450 (CYP, P450) monooxygenases, particularly human CYP2B6 and rat CYP2B1, metabolize separated atropisomers of 2,2',3,6-tetrachlorobiphenyl (CB45) and 2,2',3,4',6-pentachlorobiphenyl (CB91) to dechlorinated and hydroxylated metabolites. Docking studies using human CYP2B6 predict 4'-hydroxy (OH)-CB45 from (aR)-CB45 as a major metabolite of CB45. Di-OH- and dechlorinated OH-metabolites from human CYP2B6 and rat CYP2B1 are also detected. Several hydroxylated metabolites are derived from CB91 by both P450s; 5-OH-CB91 is predicted as a major metabolite. CB91 dechlorination is also detected by identifying 3-OH-CB51. A stable conformation of PCBs in the substrate-binding cavity and close distance to P450 heme are responsible for high metabolizing activities. As hydroxylation and dechlorination change PCB toxicity, this approach helps understand the possible toxicity of chiral PCBs in mammals.
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Affiliation(s)
- Hideyuki Inui
- Biosignal Research Center, Kobe University, 1-1 Rokkodaicho, Nada-ku, Kobe, Hyogo 657-8501, Japan
- Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodaicho, Nada-ku, Kobe, Hyogo 657-8501, Japan
| | - Terushi Ito
- Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodaicho, Nada-ku, Kobe, Hyogo 657-8501, Japan
| | - Chiharu Miwa
- Faculty of Agriculture, Kobe University, 1-1 Rokkodaicho, Nada-ku, Kobe, Hyogo 657-8501, Japan
| | - Yuki Haga
- Hyogo Prefectural Institute of Environmental Sciences, 3-1-18 Yukihiracho, Suma-ku, Kobe, Hyogo 654-0037, Japan
| | - Makoto Kubo
- Laboratory of Drug Design and Medicinal Chemistry, Showa Pharmaceutical University, 3-3165 Higashi-Tamagawagakuen, Machida, Tokyo 194-8543, Japan
| | - Toshimasa Itoh
- Laboratory of Drug Design and Medicinal Chemistry, Showa Pharmaceutical University, 3-3165 Higashi-Tamagawagakuen, Machida, Tokyo 194-8543, Japan
| | - Keiko Yamamoto
- Laboratory of Drug Design and Medicinal Chemistry, Showa Pharmaceutical University, 3-3165 Higashi-Tamagawagakuen, Machida, Tokyo 194-8543, Japan
| | - Masayuki Miyaoka
- Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Tadashi Mori
- Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Harunobu Tsuzuki
- Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodaicho, Nada-ku, Kobe, Hyogo 657-8501, Japan
| | - Shintaro Mise
- Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodaicho, Nada-ku, Kobe, Hyogo 657-8501, Japan
| | - Erika Goto
- Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodaicho, Nada-ku, Kobe, Hyogo 657-8501, Japan
| | - Chisato Matsumura
- Hyogo Prefectural Institute of Environmental Sciences, 3-1-18 Yukihiracho, Suma-ku, Kobe, Hyogo 654-0037, Japan
| | - Takeshi Nakano
- Research Center for Environmental Preservation, Osaka University, 2-4 Yamadaoka, Suita, Osaka 565-0871, Japan
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Kucey AS, Velenosi TJ, Tonial NC, Tieu A, RaoPeters AAE, Urquhart BL. The effect of chronic kidney disease on CYP2B expression and activity in male Wistar rats. Pharmacol Res Perspect 2019; 7:e00475. [PMID: 31049204 PMCID: PMC6484215 DOI: 10.1002/prp2.475] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Accepted: 04/02/2019] [Indexed: 12/17/2022] Open
Abstract
Chronic kidney disease (CKD) is characterized by progressive reduction in kidney function over time. CKD affects greater than 10% of the population and its incidence is on the rise due to the growing prevalence of its risk factors. Previous studies demonstrated CKD alters nonrenal clearance of drugs in addition to reducing renal clearance. We assessed the function and expression of hepatic CYP2B enzymes using a rat model of CKD. CKD was induced in Wistar rats by supplementing their chow with adenine and confirmed through the detection of elevated uremic toxins in plasma. Liver enzymes AST and ALT were unchanged by the adenine diet. Bupropion was used as a probe substrate for hepatic CYP2B function using rat liver microsomes. The resulting metabolite, hydroxy-bupropion, and bupropion were quantified by ultra-performance liquid chromatography coupled to time-of-flight mass spectrometry. Level of mRNA and protein were determined by RT-PCR and Western blot, respectively. The results of our study demonstrate that CYP2B1 is downregulated in a rat model of CKD. CYP2B1 mRNA level was significantly decreased (88%, P < 0.001) in CKD relative to control. Similarly, maximal enzymatic velocity (Vmax) for CYP2B was decreased by 46% in CKD relative to control (P < 0.0001). Previous studies involving patients with CKD demonstrated altered bupropion pharmacokinetics compared to control. Hence, our results suggest that these alterations may be mediated by attenuated CYP2B hepatic metabolism. This finding may partially explain the alterations in pharmacokinetics and nonrenal drug clearance frequently observed in patients with CKD.
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Affiliation(s)
- Andrew S. Kucey
- Department of Physiology and PharmacologySchulich School of Medicine and DentistryLondonOntarioCanada
| | - Thomas J. Velenosi
- Department of Physiology and PharmacologySchulich School of Medicine and DentistryLondonOntarioCanada
| | - Nicholas C. Tonial
- Department of Physiology and PharmacologySchulich School of Medicine and DentistryLondonOntarioCanada
| | - Alvin Tieu
- Department of Physiology and PharmacologySchulich School of Medicine and DentistryLondonOntarioCanada
| | - Adrien A. E. RaoPeters
- Department of Physiology and PharmacologySchulich School of Medicine and DentistryLondonOntarioCanada
| | - Brad L. Urquhart
- Department of Physiology and PharmacologySchulich School of Medicine and DentistryLondonOntarioCanada
- Lawson Health Research InstituteLondonOntarioCanada
- Department of Medicine Division of NephrologySchulich School of Medicine and DentistryLondonOntarioCanada
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Migliaccio V, Scudiero R, Sica R, Lionetti L, Putti R. Oxidative stress and mitochondrial uncoupling protein 2 expression in hepatic steatosis induced by exposure to xenobiotic DDE and high fat diet in male Wistar rats. PLoS One 2019; 14:e0215955. [PMID: 31022254 PMCID: PMC6483212 DOI: 10.1371/journal.pone.0215955] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Accepted: 04/11/2019] [Indexed: 02/07/2023] Open
Abstract
Oxidative stress plays a key role in steatohepatitis induced by both xenobiotic agents and high fat diet (HFD). The present study aimed to evaluate hepatic oxidative stress and anti-oxidant systems response in rats exposed to HFD and/or non-toxic dose of dichlorodiphenyldichloroethylene (DDE), the first metabolite of dichlorodiphenyltrichloroethane. Groups of 8 rats were so treated for 4 weeks: 1- standard diet (N group); 2- standard diet plus DDE (10 mg/kg b.w.) (N+DDE group); 3- HFD (D group); 4- HFD plus DDE (D+DDE group). Oxidative stress was analyzed by determining malondialdehyde as lipid peroxidation product, while the anti-oxidant systems were evaluating by measuring the levels of the principal cytosolic and mitochondrial antioxidant proteins and enzymes, namely superoxide dismutase 1 and 2 (SOD1, SOD2), glutathione peroxidase 1 (GPx1) and uncoupling protein 2 (UCP2) involved in the control of hepatic reactive oxygens species (ROS) accumulation. The results showed malondialdehyde accumulation in livers of all groups, confirming the pro-oxidant effects of both HFD and DDE, but with a greater effect of DDE in absence of HFD. In addition, we found different levels of the analyzed anti-oxidant systems in the different groups. DDE mainly induced UCP2 and SOD2, while HFD mainly induced GPx1. Noteworthy, in the condition of simultaneous exposure to DDE and HFD, the anti-oxidant response was more similar to the one induced by HFD than to the response induced by DDE. Present findings confirmed that both HFD and xenobiotic exposure induced hepatic oxidative stress and showed that the anti-oxidant defense response was not the same in the diverse groups, suggesting that UCP2 induction could be an adaptive response to limit excessive ROS damage, mainly in condition of xenobiotic exposure.
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Affiliation(s)
- Vincenzo Migliaccio
- Department of Biology, University of Naples, Federico II, Naples, Italy
- Department of Chemistry and Biology “Adolfo Zambelli”, University of Salerno, Fisciano, Italy
| | - Rosaria Scudiero
- Department of Biology, University of Naples, Federico II, Naples, Italy
| | - Raffaella Sica
- Department of Biology, University of Naples, Federico II, Naples, Italy
| | - Lillà Lionetti
- Department of Chemistry and Biology “Adolfo Zambelli”, University of Salerno, Fisciano, Italy
| | - Rosalba Putti
- Department of Biology, University of Naples, Federico II, Naples, Italy
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Abstract
Careful choice of the animal model is essential, if research is to be conducted efficiently, by using the minimum number of animals in order to provide the maximum amount of information. Inbred strains of rodents provide an excellent way of controlling and investigating genetic variation in characters of interest and in response to experimental treatments. Outbred stocks, in which genetic and non-genetic factors are inextricably mixed, are much less suitable, because random and uncontrolled genetic variation tends to obscure any treatment responses. In some cases, the use of inbred strains has led to major advances in scientific understanding. The specific example given here is in the understanding of host–parasite relationships but, more generally, inbred strains have been of critical importance in research which has resulted in the award of at least 17 Nobel prizes. And yet, despite the extensive literature on the properties and scientific value of inbred strains, many scientists continue to use outbred stocks in the mistaken belief that the use of such animals will, in some mysterious way, make their research more applicable to humans. There is really no evidence that this is so, and there is much evidence that the use of inbred strains has been highly successful in many disciplines.
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Affiliation(s)
- Michael F W Festing
- FRAME, Russell & Burch House, 96-98 North Sherwood Street, Nottingham NG1 4EE, UK
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Dong H, Lu G, Yan Z, Liu J, Nkoom M, Yang H. Responses of antioxidant and biotransformation enzymes in Carassius carassius exposed to hexabromocyclododecane. Environ Toxicol Pharmacol 2018; 62:46-53. [PMID: 29960092 DOI: 10.1016/j.etap.2018.06.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Revised: 06/04/2018] [Accepted: 06/24/2018] [Indexed: 06/08/2023]
Abstract
The ubiquitous existence of hexabromocyclododecane (HBCD) in environmental matrices has made it attractive to both field investigators as well as laboratory researchers. However, literature on the biological effects caused by HBCD on aquatic vertebrates seldom exist. This has inevitably increased the difficulty of toxicological assessment in the aquatic environment. Juvenile crucian carp (Carassius carassius) were exposed (flow-through) to different concentrations of technical HBCD (nominal 2, 20, 200 μg L-1) for 7 days to determine the responses of antioxidant and biotransformation enzymes. HBCD was found to be increasingly bioconcentrated in the fish livers as time proceeds. Also, the contribution of α-HBCD exhibited an enhancement from 13% in the exposure solutions to 24% in crucian carp, still much lower than in wild fishes (ca. 80%). HBCD induced activities of antioxidant enzymes in most cases, as well as increased level of lipid peroxidation. In contrast to the weak response of 7-ethoxyresorufin-O-deethylase (EROD), 7-pentoxyresorufin-O-depentylase (PROD) activity was generally induced in a time-dependent manner with peaks at day 2. Phase II enzyme Glutathione-S-transferase (GST) showed a dose-dependent induction with maximums in the 20 μg L-1 treatment at all the four timepoints of 1, 2, 4 and 7 days. Some enzymatic responses showed good associations, indicating coordinated functions. To sum up, tHBCD exposure in the present circumstance had produced an ecological stress to crucian carp. The low levels of biotransformation and slow rates of bioisomerization suggest a possible long-term toxic effect, especially around HBCD point sources.
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Affiliation(s)
- Huike Dong
- Key Laboratory of Integrated Regulation and Resources Development of Shallow Lakes of Ministry of Education, College of Environment, Hohai University, Nanjing 210098, China
| | - Guanghua Lu
- Key Laboratory of Integrated Regulation and Resources Development of Shallow Lakes of Ministry of Education, College of Environment, Hohai University, Nanjing 210098, China; Water Conservancy Project & Civil Engineering College, Tibet Agriculture & Animal Husbandry University, Linzhi 860000, China.
| | - Zhenhua Yan
- Key Laboratory of Integrated Regulation and Resources Development of Shallow Lakes of Ministry of Education, College of Environment, Hohai University, Nanjing 210098, China
| | - Jianchao Liu
- Key Laboratory of Integrated Regulation and Resources Development of Shallow Lakes of Ministry of Education, College of Environment, Hohai University, Nanjing 210098, China
| | - Matthew Nkoom
- Key Laboratory of Integrated Regulation and Resources Development of Shallow Lakes of Ministry of Education, College of Environment, Hohai University, Nanjing 210098, China
| | - Haohan Yang
- Key Laboratory of Integrated Regulation and Resources Development of Shallow Lakes of Ministry of Education, College of Environment, Hohai University, Nanjing 210098, China
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Gong Y, Zhang H, Geng N, Xing L, Fan J, Luo Y, Song X, Ren X, Wang F, Chen J. Short-chain chlorinated paraffins (SCCPs) induced thyroid disruption by enhancement of hepatic thyroid hormone influx and degradation in male Sprague Dawley rats. Sci Total Environ 2018; 625:657-666. [PMID: 29304504 DOI: 10.1016/j.scitotenv.2017.12.251] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2017] [Revised: 12/20/2017] [Accepted: 12/21/2017] [Indexed: 05/22/2023]
Abstract
Short-chain chlorinated paraffins (SCCPs) are known to disturb thyroid hormone (TH) homeostasis in rodents. However, the mechanism remains to be fully characterized. In this study, male Sprague Dawley rats received SCCPs (0, 1, 10, or 100mg/kg/day) via gavage once a day for consecutive 28days. Plasma and hepatic TH concentrations, thyrocyte structure, as well as thyroid and hepatic mRNA and protein levels of genes associated with TH homeostasis were examined. Moreover, we performed molecular docking to predict interactions between constitutive androstane receptor (CAR), a key regulator in xenobiotic-induced TH metabolism, with different SCCP molecules. Exposure to SCCPs significantly decreased the circulating free thyroxine (T4) and triiodothyronine (T3) levels, but increased thyroid-stimulating hormone (TSH) levels by a feedback mechanism. Decreased hepatic T4 and increased hepatic T3 levels were also seen after 100mg/kg/day SCCPs exposure. SCCPs didn't show any significant effects on the expression of thyroid TH synthesis genes or thyrocyte structure. However, stimulation effects were observed for mRNA and protein levels of hepatic uridine diphosphoglucuronosyl transferase (UGT) 1A1 and organic anion transporter 2, suggesting an accelerated TH metabolism in rat liver. The increased cytochrome P450 2B1 but not 1A1 mRNA and protein levels indicated that the CAR signaling was activated by SCCPs exposure. According to docking analysis, SCCPs form hydrophobic interactions with CAR and the binding affinity shows dependency on chlorine content. Overall, our data showed that CAR implicated enhancement of hepatic TH influx and degradation could be the main cause for SCCPs induced TH deficiency in male rats.
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Affiliation(s)
- Yufeng Gong
- CAS Key Laboratory of Separation Sciences for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Haijun Zhang
- CAS Key Laboratory of Separation Sciences for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Ningbo Geng
- CAS Key Laboratory of Separation Sciences for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Liguo Xing
- Safety Evaluation Center of Shenyang Research Institute of Chemical Industry Ltd., Shenyang 110021, China
| | - Jingfeng Fan
- National Marine Environmental Monitoring Center, Dalian 116023, China
| | - Yun Luo
- CAS Key Laboratory of Separation Sciences for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xiaoyao Song
- CAS Key Laboratory of Separation Sciences for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Xiaoqian Ren
- CAS Key Laboratory of Separation Sciences for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Feidi Wang
- CAS Key Laboratory of Separation Sciences for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jiping Chen
- CAS Key Laboratory of Separation Sciences for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
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10
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Cho SJ, Kim SB, Cho HJ, Chong S, Chung SJ, Kang IM, Lee JI, Yoon IS, Kim DD. Effects of Nonalcoholic Fatty Liver Disease on Hepatic CYP2B1 and in Vivo Bupropion Disposition in Rats Fed a High-Fat or Methionine/Choline-Deficient Diet. J Agric Food Chem 2016; 64:5598-5606. [PMID: 27321734 DOI: 10.1021/acs.jafc.6b01663] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Nonalcoholic fatty liver disease (NAFLD) refers to hepatic pathologies, including simple fatty liver (SFL), nonalcoholic steatohepatitis (NASH), fibrosis, and cirrhosis, that may progress to hepatocellular carcinoma. These liver disease states may affect the activity and expression levels of drug-metabolizing enzymes, potentially resulting in an alteration in the pharmacokinetics, therapeutic efficacy, and safety of drugs. This study investigated the hepatic cytochrome P450 (CYP) 2B1-modulating effect of a specific NAFLD state in dietary rat models. Sprague-Dawley rats were given a methionine/choline-deficient (MCD) or high-fat (HF) diet to induce NASH and SFL, respectively. The induction of these disease states was confirmed by plasma chemistry and liver histological analysis. Both the protein and mRNA levels of hepatic CYP2B1 were considerably reduced in MCD diet-fed rats; however, they were similar between the HF diet-fed and control rats. Consistently, the enzyme-kinetic and pharmacokinetic parameters for CYP2B1-mediated bupropion metabolism were considerably reduced in MCD diet-fed rats; however, they were also similar between the HF diet-fed and control rats. These results may promote a better understanding of the influence of NAFLD on CYP2B1-mediated metabolism, which could have important implications for the safety and pharmacokinetics of drug substrates for the CYP2B subfamily in patients with NAFLD.
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Affiliation(s)
- Sung-Joon Cho
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University , Seoul 08826, Republic of Korea
| | - Sang-Bum Kim
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University , Seoul 08826, Republic of Korea
| | - Hyun-Jong Cho
- College of Pharmacy, Kangwon National University , Gangwon 24341, Republic of Korea
| | - Saeho Chong
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University , Seoul 08826, Republic of Korea
| | - Suk-Jae Chung
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University , Seoul 08826, Republic of Korea
| | - Il-Mo Kang
- Advanced Geo-materials R&D Department, Korea Institute of Geoscience and Mineral Resources, Pohang Branch , Gyeongbuk 37559, Republic of Korea
| | - Jangik Ike Lee
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University , Seoul 08826, Republic of Korea
| | - In-Soo Yoon
- College of Pharmacy and Natural Medicine Research Institute, Mokpo National University , Jeonnam 58554, Republic of Korea
| | - Dae-Duk Kim
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University , Seoul 08826, Republic of Korea
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11
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de-Miranda AS, Kuriyama SN, da-Silva CS, do-Nascimento MSC, Parente TEM, Paumgartten FJR. Thyroid hormone disruption and cognitive impairment in rats exposed to PBDE during postnatal development. Reprod Toxicol 2016; 63:114-24. [PMID: 27233481 DOI: 10.1016/j.reprotox.2016.05.017] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Revised: 05/04/2016] [Accepted: 05/20/2016] [Indexed: 01/04/2023]
Abstract
Polybrominated diphenyl ether flame-retardants (PBDEs) are thyroid-disrupting environmental chemicals. We investigated the effects of postnatal exposure to DE-71 (a mixture of tetra- and penta-brominated congeners), n-propylthiouracil (PTU) and thyroxine (T4) replacement on open-field (OF) and radial maze (RAM) tests. Wistar rats (5 males/5 females per litter, 32 litters) were treated orally (PND 5-22) with PTU (4mg/kg bw/d), DE-71 (30mg/kg bw/d), with and without co-administration of T4 (15μg/kg bw/d, sc). PTU depressed T4 serum levels and body weight gain and enlarged thyroid gland. Although decreasing T4 levels, DE-71 did not change thyroid and body weights. PTU-treated rats showed hyperactivity (PND 42 and 70), and working and reference memory learning deficits (RAM, PND 100). Although not altering motor activity and working memory, DE-71 caused a reference memory deficit (females only). T4 co-administration averted hypothyroxinemia and long-term cognitive deficits caused by PTU and DE-71.
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Affiliation(s)
- Andressa S de-Miranda
- Laboratory of Environmental Toxicology, National School of Public Health, Oswaldo Cruz Foundation, Rio de Janeiro, RJ 21040-361, Brazil
| | - Sergio N Kuriyama
- Laboratory of Environmental Toxicology, National School of Public Health, Oswaldo Cruz Foundation, Rio de Janeiro, RJ 21040-361, Brazil
| | - Camille S da-Silva
- Laboratory of Environmental Toxicology, National School of Public Health, Oswaldo Cruz Foundation, Rio de Janeiro, RJ 21040-361, Brazil
| | - Monicke S C do-Nascimento
- Laboratory of Environmental Toxicology, National School of Public Health, Oswaldo Cruz Foundation, Rio de Janeiro, RJ 21040-361, Brazil
| | - Thiago E M Parente
- Laboratory of Environmental Toxicology, National School of Public Health, Oswaldo Cruz Foundation, Rio de Janeiro, RJ 21040-361, Brazil
| | - Francisco J R Paumgartten
- Laboratory of Environmental Toxicology, National School of Public Health, Oswaldo Cruz Foundation, Rio de Janeiro, RJ 21040-361, Brazil.
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12
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Gregoraszczuk EL, Dobrzanska G, Karpeta A. Effects of 2,2',4,4'-tetrabromodiphenyl ether (BDE47) on the enzymes of phase I (CYP2B1/2) and phase II (SULT1A and COMT) metabolism, and differences in the action of parent BDE-47 and its hydroxylated metabolites, 5-OH-BDE-47 and 6-OH-BDE47, on steroid secretion by luteal cells. Environ Toxicol Pharmacol 2015; 40:498-507. [PMID: 26310508 DOI: 10.1016/j.etap.2015.07.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Revised: 07/02/2015] [Accepted: 07/08/2015] [Indexed: 06/04/2023]
Abstract
UNLABELLED In this study we determined the effects of BDE-47 on the expression and activity of phase I (CYP2B1/2) and phase II (SULT1A and COMT) enzymes, and assessed the actions of BDE-47 and its metabolites on luteal steroidogenesis. Luteal cells collected during early (ELP), middle (MLP) and late (LLP) luteal phase were exposed to BDE-47 (0.5, 25, and 50ng/ml) or metabolites (2.5, 5 and 25ng/ml). BDE-47 decreased CYP2B1/2 activity and expression but had no effect on SULT1A or COMT. BDE-47 exerted a stimulatory action on estrogen secretion in MLP and an inhibitory in LLP, but had no effect on progesterone secretion. 5-OH-BDE-47 and 6-OH-BDE-47 decreased progesterone, but had no effect on estrogen secretion. CONCLUSIONS The inhibitory effect of BDE-47 on CYP2B1/2 suggests the possibility of BDE-47 accumulation in the corpus luteum; by affecting steroid secretion and steroidogenesis enzymes, BDE-47 and its metabolites can be responsible for shortening luteal phase.
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Affiliation(s)
- E L Gregoraszczuk
- Department of Physiology and Toxicology of Reproduction, Chair of Animal Physiology, Institute of Zoology, Jagiellonian University, Gronostajowa 9, 30-387 Krakow, Poland.
| | - G Dobrzanska
- Department of Physiology and Toxicology of Reproduction, Chair of Animal Physiology, Institute of Zoology, Jagiellonian University, Gronostajowa 9, 30-387 Krakow, Poland
| | - A Karpeta
- Department of Physiology and Toxicology of Reproduction, Chair of Animal Physiology, Institute of Zoology, Jagiellonian University, Gronostajowa 9, 30-387 Krakow, Poland
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13
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Larsen K, Najle R, Lifschitz A, Maté ML, Lanusse C, Virkel GL. Effects of Sublethal Exposure to a Glyphosate-Based Herbicide Formulation on Metabolic Activities of Different Xenobiotic-Metabolizing Enzymes in Rats. Int J Toxicol 2014; 33:307-318. [PMID: 24985121 DOI: 10.1177/1091581814540481] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2023]
Abstract
The activities of different xenobiotic-metabolizing enzymes in liver subcellular fractions from Wistar rats exposed to a glyphosate (GLP)-based herbicide (Roundup full II) were evaluated in this work. Exposure to the herbicide triggered protective mechanisms against oxidative stress (increased glutathione peroxidase activity and total glutathione levels). Liver microsomes from both male and female rats exposed to the herbicide had lower (45%-54%, P < 0.01) hepatic cytochrome P450 (CYP) levels compared to their respective control animals. In female rats, the hepatic 7-ethoxycoumarin O-deethylase (a general CYP-dependent enzyme activity) was 57% higher (P < 0.05) in herbicide-exposed compared to control animals. Conversely, this enzyme activity was 58% lower (P < 0.05) in male rats receiving the herbicide. Lower (P < 0.05) 7-ethoxyresorufin O-deethlyase (EROD, CYP1A1/2 dependent) and oleandomycin triacetate (TAO) N-demethylase (CYP3A dependent) enzyme activities were observed in liver microsomes from exposed male rats. Conversely, in females receiving the herbicide, EROD increased (123%-168%, P < 0.05), whereas TAO N-demethylase did not change. A higher (158%-179%, P < 0.01) benzyloxyresorufin O-debenzylase (a CYP2B-dependent enzyme activity) activity was only observed in herbicide-exposed female rats. In herbicide-exposed rats, the hepatic S-oxidation of methimazole (flavin monooxygenase dependent) was 49% to 62% lower (P < 0.001), whereas the carbonyl reduction of menadione (a cytosolic carbonyl reductase-dependent activity) was higher (P < 0.05). Exposure to the herbicide had no effects on enzymatic activities dependent on carboxylesterases, glutathione transferases, and uridinediphospho-glucuronosyltransferases. This research demonstrated certain biochemical modifications after exposure to a GLP-based herbicide. Such modifications may affect the metabolic fate of different endobiotic and xenobiotic substances. The pharmacotoxicological significance of these findings remains to be clarified.
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Affiliation(s)
- Karen Larsen
- Laboratorio de Biología y Ecotoxicología, Facultad de Ciencias Veterinarias, UNCPBA, Tandil, Argentina
- Laboratorio de Farmacología, Facultad de Ciencias Veterinarias (UNCPBA), Centro de Investigación Veterinaria Tandil (CIVETAN-CONICET), Tandil, Argentina
| | - Roberto Najle
- Laboratorio de Biología y Ecotoxicología, Facultad de Ciencias Veterinarias, UNCPBA, Tandil, Argentina
| | - Adrián Lifschitz
- Laboratorio de Farmacología, Facultad de Ciencias Veterinarias (UNCPBA), Centro de Investigación Veterinaria Tandil (CIVETAN-CONICET), Tandil, Argentina
| | - María L Maté
- Laboratorio de Farmacología, Facultad de Ciencias Veterinarias (UNCPBA), Centro de Investigación Veterinaria Tandil (CIVETAN-CONICET), Tandil, Argentina
| | - Carlos Lanusse
- Laboratorio de Farmacología, Facultad de Ciencias Veterinarias (UNCPBA), Centro de Investigación Veterinaria Tandil (CIVETAN-CONICET), Tandil, Argentina
| | - Guillermo L Virkel
- Laboratorio de Farmacología, Facultad de Ciencias Veterinarias (UNCPBA), Centro de Investigación Veterinaria Tandil (CIVETAN-CONICET), Tandil, Argentina
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14
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Binder S, Lewis AL, Löhr JM, Keese M. Extravascular use of drug-eluting beads: A promising approach in compartment-based tumor therapy. World J Gastroenterol 2013; 19:7586-7593. [PMID: 24282349 PMCID: PMC3837257 DOI: 10.3748/wjg.v19.i43.7586] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2013] [Revised: 09/05/2013] [Accepted: 09/17/2013] [Indexed: 02/06/2023] Open
Abstract
Intraperitoneal carcinomatosis (PC) may occur with several tumor entities. The prognosis of patients suffering from PC is usually poor. Present treatment depends on the cancer entity and includes systemic chemotherapy, radiation therapy, hormonal therapy and surgical resection. Only few patients may also benefit from hyperthermic intraperitoneal chemotherapy with a complete tumor remission. These therapies are often accompanied by severe systemic side-effects. One approach to reduce side effects is to target chemotherapeutic agents to the tumor with carrier devices. Promising experimental results have been achieved using drug-eluting beads (DEBs). A series of in vitro and in vitro experiments has been conducted to determine the suitability of their extravascular use. These encapsulation devices were able to harbor CYP2B1 producing cells and to shield them from the hosts immune system when injected intratumorally. In this way ifosfamide - which is transformed into its active metabolites by CYP2B1 - could be successfully targeted into pancreatic tumor growths. Furthermore DEBs can be used to target chemotherapeutics into the abdominal cavity for treatment of PC. If CYP2B1 producing cells are proven to be save for usage in man and if local toxic effects of chemotherapeutics can be controlled, DEBs will become promising tools in compartment-based anticancer treatment.
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15
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Lu Z, Ma G, Veinot JGC, Wong CS. Disruption of biomolecule function by nanoparticles: how do gold nanoparticles affect Phase I biotransformation of persistent organic pollutants? Chemosphere 2013; 93:123-32. [PMID: 23763865 DOI: 10.1016/j.chemosphere.2013.05.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2013] [Revised: 04/23/2013] [Accepted: 05/02/2013] [Indexed: 05/22/2023]
Abstract
The potential influence of nanoparticles on cytochrome P-450 (CYP) isozyme mediated Phase I biotransformation of persistent organic pollutants (POPs) in vitro was investigated using citrate-capped gold nanoparticles (AuNPs) and 2,2',3,5',6-pentachlorobiphenyl (PCB 95) as the probe nanoparticle and compound, respectively. AuNPs affected the biotransformation activity of rat CYP2B1 and changed the atropisomeric composition of PCB 95, depending on the incubation time and the AuNP concentration. Electrostatic repulsion between citrate-coated AuNPs and rat CYP2B1 may influence the active conformation of the isozyme and consequently affect its activity and stereoselectivity. In addition, the effects of AuNPs on rat CYP2B1 activity also appeared to be through interference with the CYP catalytic cycle's electron transfer chain. Incubations with AuNPs had a decline in buffer conductance and an absorbance band red shift of AuNPs, from electrostatic interactions of K(+) with negatively-charged AuNP aggregates. These ionic strength changes affected the formation rate of nicotinamide adenine dinucleotide phosphate, which provides electrons for the oxidative reaction cycle, and the biotransformation activity and stereoselectivity of CYP. This study suggests that charged nanoparticles may be able to alter the functions of biomolecules directly, by electrostatic interaction, or indirectly, by changes to the surrounding ionic strength. These factors should be taken into account for further understanding and prediction of the environmental behavior and fate of POPs and nanoparticles.
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Affiliation(s)
- Zhe Lu
- Department of Chemistry, University of Manitoba, Winnipeg, MB, Canada R3T 2N2
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16
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Yang J, An J, Li M, Hou X, Qiu X. Characterization of chicken cytochrome P450 1A4 and 1A5: inter-paralog comparisons of substrate preference and inhibitor selectivity. Comp Biochem Physiol C Toxicol Pharmacol 2013; 157:337-43. [PMID: 23474502 DOI: 10.1016/j.cbpc.2013.02.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2012] [Revised: 02/23/2013] [Accepted: 02/25/2013] [Indexed: 12/17/2022]
Abstract
The chicken (Gallus gallus) is one of the most economically important domestic animals and also an avian model species. Chickens have two CYP1A genes (CYP1A4 and CYP1A5) which are orthologous to mammalian CYP1A1 and CYP1A2. Although the importance of chicken CYP1As in metabolism of endogenous compounds and xenobiotics is well recognized, their enzymatic properties, substrate preference and inhibitor selectivity remain poorly understood. In this study, functional enzymes of chicken CYP1A4 and CYP1A5 were successfully produced in Escherichia coli (E. coli). The substrate preference and inhibitor specificity of the two chicken CYP1As were compared. Kinetic results showed that the enzymatic parameters (K(m), V(max), V(max)/K(m)) for ethoxyresorufin O-deethylase (EROD) and benzyloxyresorufin O-debenzylase (BROD) differed between CYP1A4 and CYP1A5, while no significant difference was observed for methoxyresorufin O-demethylase (MROD). Lower K(m) of CYP1A4 for BROD suggests that CYP1A4 has a greater binding affinity to benzyloxyresorufin than either ethoxyresorufin or methoxyresorufin. The highest V(max)/K(m) ratio was seen in BROD activity for CYP1A4 and in MROD for CYP1A5 respectively. These results indicate that substrate preference of chicken CYP1As is more notably distinguished by BROD activity and CYP1A5 prefers shorter alkoxyresorufins resembling its mammalian ortholog CYP1A2. Differential patterns of MROD inhibition were observed between CYP1As and among the five CYP inhibitors (α-naphthoflavone, furafylline, piperonyl butoxide, erythromycin and ketoconazole). α-Naphthoflavone was determined to be a potent MROD inhibitor of both CYP1A4 and CYP1A5. In contrast, no or only a trace inhibitory effect (<15%) was observed by erythromycin at a concentration of 500 μM. Stronger inhibition of MROD activity was found in CYP1A5 than CYP1A4 by relatively small molecules α-naphthoflavone, piperonyl butoxide and furafylline. AROD kinetics and inhibition profiles between chicken CYP1A4 and CYP1A5 demonstrate that the two paralogous members of the CYP1A subfamily have distinct enzymatic properties, reflecting differences in the active site geometry between CYP1A4 and CYP1A5. These findings suggest that CYP1A4 and CYP1A5 play partially overlapping but distinctly different physiological and toxicological roles in the chicken.
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Affiliation(s)
- Jiannan Yang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
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17
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Li H, Wang YG, Ma ZC, Zhou SS, Liang QD, Xiao CR, Tan HL, Tang XL, Li H, Shen GL, Zhang BL, Gao Y. [Effect of shenfu injection on CYP450s of rat liver]. Yao Xue Xue Bao 2013; 48:728-733. [PMID: 23888697] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The paper is to report the study of the effect of Shenfu injection on the enzyme activity of liver CYP450 and its mRNA level of rat liver. Microsome of rat liver was prepared after intravenous administration of Shenfu injection for 7 days. The enzyme activity was quantified by Cocktail method. Meanwhile, the mRNA expression of CYP1A2, CYP2B1/2, CYP2C11 and CYP3A1 in the liver was detected by RT-PCR. Shenfu injection obviously induced the enzyme activities of CYP2B and CYP2C. Meantime Shenfu injection decreased the enzyme activities of CYP1A2 and CYP3A. The mRNA levels of CYP2B and CYP2C were also induced in rats treated with Shenfu injection. But it obviously inhibited the mRNA level of CYP1A2 and CYP3A. Since the enzyme activity and mRNA level were obviously changed after administration, the potential effect of drug-drug interaction should be concerned.
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Affiliation(s)
- Han Li
- Tianjin University of Traditional Chinese Medicine, Tianjin 300193, China
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18
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Tabrez S, Ahmad M. Cytochrome P450 system as potential biomarkers of certain toxicants: comparison between plant and animal models. Environ Monit Assess 2013; 185:2977-2987. [PMID: 22773083 DOI: 10.1007/s10661-012-2765-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2012] [Accepted: 06/25/2012] [Indexed: 06/01/2023]
Abstract
In present study, we measured the activities of some selected cytochrome P450 isozymes like ethoxyresorufin-o-deethylase (EROD), pentoxyresorufin-o-deethylase (PROD), and N-nitrosodimethylamine demethylase (NDMA-d) treating experimental rats with different environmental toxicants, namely trichloroethylene (TCE), heavy metal mixture, and ethyl alcohol individually or in combination and by exposing the Allium cepa bulbs to increasing concentration of TCE for 48 h. In animal system, NDMA-d activity displayed a remarkable amplification by 4.2-fold in the liver of alcohol ingested rats compared with control animals. TCE intake also resulted in a marked increase of around 3.8-fold and 1.2-fold in rats' NDMA-d activity in the liver and kidney, respectively. In onion bulbs, an amazing rise in the activity of test enzymes was recorded in a dose-dependent manner. Among the said enzymes, PROD showed maximum increase up to the extent of 22-fold in comparison with control at 20 ppm of TCE exposure, whereas NDMA-d and EROD showed 11- and 9-fold increase in enzymatic activity, respectively, compared with the control. Based on this study, we conclude and advocate that all the selected isozymes of CYP450 system, viz. PROD, NDMA-d, and EROD can act as potent biomarkers in plant system for assessing the TCE pollution.
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Affiliation(s)
- Shams Tabrez
- King Fahd Medical Research Center, King Abdulaziz University, Jeddah 21589, Saudi Arabia.
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19
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Kamiyama N, Yamamoto M, Saiga H, Ma JS, Ohshima J, Machimura S, Sasai M, Kimura T, Ueda Y, Kayama H, Takeda K. CREBH determines the severity of sulpyrine-induced fatal shock. PLoS One 2013; 8:e55800. [PMID: 23409047 PMCID: PMC3567110 DOI: 10.1371/journal.pone.0055800] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2012] [Accepted: 01/02/2013] [Indexed: 11/18/2022] Open
Abstract
Although the pyrazolone derivative sulpyrine is widely used as an antipyretic analgesic drug, side effects, including fatal shock, have been reported. However, the molecular mechanism underlying such a severe side effect is largely unclear. Here, we report that the transcription factor CREBH that is highly expressed in the liver plays an important role in fatal shock induced by sulpyrine in mice. CREBH-deficient mice were resistant to experimental fatal sulpyrine shock. We found that sulpyrine-induced expression of cytochrome P450 2B (CYP2B) family genes, which are involved in sulpyrine metabolism, in the liver was severely impaired in CREBH-deficient mice. Moreover, introduction of CYP2B in CREBH-deficient liver restored susceptibility to sulpyrine. Furthermore, ectopic expression of CREBH up-regulated CYP2B10 promoter activity, and in vivo knockdown of CREBH in wild-type mice conferred a significant resistance to fatal sulpyrine shock. These data demonstrate that CREBH is a positive regulator of CYP2B in response to sulpyrine administration, which possibly results in fatal shock.
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Affiliation(s)
- Naganori Kamiyama
- Department of Microbiology and Immunology, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan
- Laboratory of Mucosal Immunology, WPI Immunology Frontier Research Center, Osaka University, Suita, Osaka, Japan
- Laboratory of Immunoparasitology, WPI Immunology Frontier Research Center, Osaka University, Suita, Osaka, Japan
- Department of Immunoparasitology, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka, Japan
| | - Masahiro Yamamoto
- Department of Microbiology and Immunology, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan
- Laboratory of Mucosal Immunology, WPI Immunology Frontier Research Center, Osaka University, Suita, Osaka, Japan
- Laboratory of Immunoparasitology, WPI Immunology Frontier Research Center, Osaka University, Suita, Osaka, Japan
- Department of Immunoparasitology, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka, Japan
- Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Kawaguchi, Saitama, Japan
- * E-mail: (MY); (KT)
| | - Hiroyuki Saiga
- Department of Microbiology and Immunology, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan
- Laboratory of Mucosal Immunology, WPI Immunology Frontier Research Center, Osaka University, Suita, Osaka, Japan
| | - Ji Su Ma
- Department of Microbiology and Immunology, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan
- Laboratory of Mucosal Immunology, WPI Immunology Frontier Research Center, Osaka University, Suita, Osaka, Japan
- Laboratory of Immunoparasitology, WPI Immunology Frontier Research Center, Osaka University, Suita, Osaka, Japan
- Department of Immunoparasitology, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka, Japan
| | - Jun Ohshima
- Department of Microbiology and Immunology, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan
- Laboratory of Mucosal Immunology, WPI Immunology Frontier Research Center, Osaka University, Suita, Osaka, Japan
- Laboratory of Immunoparasitology, WPI Immunology Frontier Research Center, Osaka University, Suita, Osaka, Japan
- Department of Immunoparasitology, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka, Japan
| | - Sakaaki Machimura
- Department of Microbiology and Immunology, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan
- Laboratory of Mucosal Immunology, WPI Immunology Frontier Research Center, Osaka University, Suita, Osaka, Japan
- Laboratory of Immunoparasitology, WPI Immunology Frontier Research Center, Osaka University, Suita, Osaka, Japan
- Department of Immunoparasitology, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka, Japan
| | - Miwa Sasai
- Laboratory of Immunoparasitology, WPI Immunology Frontier Research Center, Osaka University, Suita, Osaka, Japan
- Department of Immunoparasitology, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka, Japan
| | - Taishi Kimura
- Department of Microbiology and Immunology, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan
- Laboratory of Mucosal Immunology, WPI Immunology Frontier Research Center, Osaka University, Suita, Osaka, Japan
| | - Yoshiyasu Ueda
- Department of Microbiology and Immunology, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan
- Laboratory of Mucosal Immunology, WPI Immunology Frontier Research Center, Osaka University, Suita, Osaka, Japan
| | - Hisako Kayama
- Department of Microbiology and Immunology, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan
- Laboratory of Mucosal Immunology, WPI Immunology Frontier Research Center, Osaka University, Suita, Osaka, Japan
- Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Kawaguchi, Saitama, Japan
| | - Kiyoshi Takeda
- Department of Microbiology and Immunology, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan
- Laboratory of Mucosal Immunology, WPI Immunology Frontier Research Center, Osaka University, Suita, Osaka, Japan
- Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Kawaguchi, Saitama, Japan
- * E-mail: (MY); (KT)
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Tatematsu K, Koide A, Morimura K, Fukushima S, Mori Y. The enhancing effect of ethanol on the mutagenic activation of N-nitrosomethylbenzylamine by cytochrome P450 2A in the rat oesophagus. Mutagenesis 2013; 28:161-9. [PMID: 23325793 DOI: 10.1093/mutage/ges066] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Alcohol consumption is frequently associated with various cancers and the enhancement of the metabolic activation of carcinogens has been proposed as a mechanism underlying this relationship. The ethanol-induced enhancement of N-nitrosodiethylamine (DEN)-mediated carcinogenesis can be attributed to an increase in hepatic activity. However, the mechanism of elevation of N-nitrosomethylbenzylamine (NMBA)-induced tumorigenesis remains unclear. To elucidate the mechanism underlying the role of ethanol in the enhancement of NMBA-induced oesophageal carcinogenesis, we evaluated the hepatic and extrahepatic levels of the cytochrome P450 (CYP) and mutagenic activation of environmental carcinogens by immunoblot analyses and Ames preincubation test, respectively, in F344 rats treated with ethanol. Five weeks of treatment with 10% ethanol added to the drinking water or two intragastric treatments with 50% ethanol, both resulted in elevated levels of CYP2E1 (1.5- to 2.3-fold) and mutagenic activities of DEN, N-nitrosodimethylamine and N-nitrosopyrrolidine in the presence of rat liver S9 (1.5- to 2.4-fold). This was not the case with CYP1A1/2, CYP2A1/2, CYP2B1/2 or CYP3A2, nor with the activities of 2-amino-3-methylimidazo[4,5-f]quinoline, 3-amino-1-methyl-5H-pyrido[4,3-b]indole, aflatoxin B(1) or other N-nitroso compounds (NOCs), including NMBA. Ethanol-induced elevations of CYP2A and CYP2E1 were observed in the oesophagus (up to 1.7- and 2.3-fold) and kidney (up to 1.5- and 1.8-fold), but not in the lung or colon. In oesophagus and kidney, the mutagenic activities of NMBA and four NOCs were markedly increased (1.3- to 2.4-fold) in treated rats. The application of several CYP inhibitors revealed that CYP2A were likely to contribute to the enhancing effect of ethanol on NMBA activation in the rat oesophagus and kidney, but that CYP2E1 failed to do so. These results showed that the enhancing effect of ethanol on NMBA-induced oesophageal carcinogenesis could be attributed to an increase in the metabolic activation of NMBA by oesophageal CYP2A during the initiation phase, and that this occurred independently of CYP2E1.
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Affiliation(s)
- Kenjiro Tatematsu
- Laboratory of Radiochemistry, Gifu Pharmaceutical University, 6-1, Mitahora-higashi 5-chome, Gifu 502-8585, Japan
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Lu Z, Kania-Korwel I, Lehmler HJ, Wong CS. Stereoselective formation of mono- and dihydroxylated polychlorinated biphenyls by rat cytochrome P450 2B1. Environ Sci Technol 2013; 47:12184-92. [PMID: 24060104 PMCID: PMC3870094 DOI: 10.1021/es402838f] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Changes in atropisomer composition of chiral polychlorinated biphenyls (PCBs) and their mono- and dihydroxylated metabolites (OH- and diOH-PCBs) via rat cytochrome P450 2B1 (CYP2B1) mediated biotransformation were investigated in vitro. Rat CYP2B1 could stereoselectively biotransform chiral PCBs to generate meta-OH-PCBs as the major metabolites after 60 min incubations. Nonracemic enantiomer fractions (EFs: concentration ratios of the (+)-atropisomer or the first-eluting atropisomer over the total concentrations of two atropisomers) of 5-OH-PCBs, were 0.17, 0.20, 0.85, 0.77, and 0.41 for incubations with PCBs 91, 95, 132, 136, and 149, respectively. CYP-mediated stereoselective formation of diOH-PCBs from OH-PCBs was observed for the first time. After 60 min stereoselective biotransformation, the EFs of both 4-OH-PCB 95 and 5-OH-PCB 95 changed from racemic (i.e., 0.50) to 0.62 and 0.46, respectively. These transformations generated statistically nonracemic 4,5-diOH-PCB 95, with EFs of 0.53 and 0.58 for 4-OH-PCB 95 and 5-OH-PCB 95 incubations, respectively. Biotransformation of PCBs 91 and 136 also generated 4,5-diOH-PCB 91 and 4,5-diOH-PCB 136, respectively. These in vitro results were consistent with that observed for stereoselective PCB biotransformation by rat liver microsomes and in vivo. Biotransformation interference between two atropisomers of PCB 136 was investigated for the first time in this study. The biotransformation process of (-)-PCB 136 was significantly disrupted by the presence of (+)-PCB 136 but not the other way around. Thus, stereoselective metabolism of chiral PCBs and OH-PCBs by CYPs is a major mechanism for atropisomer composition change of PCBs and their metabolites in the environment, with the degree of composition change dependent, at least in part, on stereoselective interference of atropisomers with each other at the enzyme level.
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Affiliation(s)
- Zhe Lu
- Department of Chemistry, University of Manitoba, Winnipeg, MB, R3T 2N2, Canada
| | - Izabela Kania-Korwel
- Department of Occupational and Environmental Health, College of Public Health, University of Iowa, Iowa City, Iowa 52242,United States
| | - Hans-Joachim Lehmler
- Department of Occupational and Environmental Health, College of Public Health, University of Iowa, Iowa City, Iowa 52242,United States
- Corresponding authors: Lehmler--Phone: +1-319-335-4310; Fax: +1-319-335-4290; Wong--Phone: +1-204-786-9335; Fax: +1-204-775-2114;
| | - Charles S. Wong
- Department of Chemistry, University of Manitoba, Winnipeg, MB, R3T 2N2, Canada
- Department of Environmental Studies and Sciences and Department of Chemistry, Richardson College for the Environment, University of Winnipeg, Winnipeg, MB, R3B 2E9, Canada
- Corresponding authors: Lehmler--Phone: +1-319-335-4310; Fax: +1-319-335-4290; Wong--Phone: +1-204-786-9335; Fax: +1-204-775-2114;
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Pogrmic-Majkic K, Kaisarevic S, Fa S, Dakic V, Glisic B, Hrubik J, Kovacevic R. Atrazine effects on antioxidant status and xenobiotic metabolizing enzymes after oral administration in peripubertal male rat. Environ Toxicol Pharmacol 2012; 34:495-501. [PMID: 22797327 DOI: 10.1016/j.etap.2012.06.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2011] [Revised: 06/06/2012] [Accepted: 06/18/2012] [Indexed: 06/01/2023]
Abstract
Previously, we reported that in vivo applied atrazine from postnatal day 23 to 50 induced strong inhibition of testicular steroidogenesis. Therefore, the aim of the present study was to investigate, in the same experimental model, the oxidative status in androgen-producing testicular interstitial compartment characterized by diminished steroidogenesis. In parallel, we determined activities of antioxidative and cytochrome P450 (CYP) xenobiotic-metabolizing enzymes in liver. To confirm the results on atrazine induced-inhibition of testicular androgenesis, we measured ex vivo production of androgen in Leydig cells. The results revealed decreased activity of antioxidant enzymes, especially glutathione S-transferase (GST), but also glutathione peroxidase (GSH-Px) and catalase (CAT) in testicular interstitial cells, in parallel with strongly diminished ex vivo basal and agonist-stimulated Leydig cell androgenesis. In liver, atrazine increased the activity of GSH-Px, GST, and CYP1A1/2 enzyme, but not lipid peroxidation. These results indicate that atrazine markedly affects both antioxidant status and androgenesis in peripubertal rats.
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Affiliation(s)
- Kristina Pogrmic-Majkic
- Laboratory for Ecotoxicology (LECOTOX), Department of Biology and Ecology, University of Novi Sad Faculty of Sciences, 21000 Novi Sad, Serbia.
| | - Sonja Kaisarevic
- Laboratory for Ecotoxicology (LECOTOX), Department of Biology and Ecology, University of Novi Sad Faculty of Sciences, 21000 Novi Sad, Serbia
| | - Svetlana Fa
- Laboratory for Ecotoxicology (LECOTOX), Department of Biology and Ecology, University of Novi Sad Faculty of Sciences, 21000 Novi Sad, Serbia
| | - Vanja Dakic
- Laboratory for Ecotoxicology (LECOTOX), Department of Biology and Ecology, University of Novi Sad Faculty of Sciences, 21000 Novi Sad, Serbia
| | - Branka Glisic
- Laboratory for Ecotoxicology (LECOTOX), Department of Biology and Ecology, University of Novi Sad Faculty of Sciences, 21000 Novi Sad, Serbia
| | - Jelena Hrubik
- Laboratory for Ecotoxicology (LECOTOX), Department of Biology and Ecology, University of Novi Sad Faculty of Sciences, 21000 Novi Sad, Serbia
| | - Radmila Kovacevic
- Laboratory for Ecotoxicology (LECOTOX), Department of Biology and Ecology, University of Novi Sad Faculty of Sciences, 21000 Novi Sad, Serbia
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Kubota A, Watanabe MX, Kim EY, Yoneda K, Tanabe S, Iwata H. Accumulation of dioxins and induction of cytochrome P450 1A4/1A5 enzyme activities in common cormorants from Lake Biwa, Japan: temporal trends and validation of national regulation on dioxins emission. Environ Pollut 2012; 168:131-137. [PMID: 22610036 DOI: 10.1016/j.envpol.2012.04.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/29/2012] [Revised: 04/11/2012] [Accepted: 04/12/2012] [Indexed: 06/01/2023]
Abstract
To validate the outcome of the national regulation on dioxins emission implemented in 1999, this study investigated temporal trends of chlorinated dioxins and related compounds (DRCs) in liver of common cormorants (Phalacrocorax carbo) collected from Lake Biwa, Japan between 2001 and 2008, as a part of the "Survey on the State of Dioxins Accumulation in Wildlife" conducted by the Ministry of the Environment, Japan. We also measured a biomarker of DRCs exposure, the cytochrome P450 1A (CYP1A)-dependent O-dealkylation activity of alkoxyresorufins (AROD), including methoxy-, ethoxy-, pentoxy- and benzyloxy-resorufins in the samples over 2001-2007. Neither TEQ nor AROD activity showed any clear declining trend over the time period, although the emission of DRCs during the corresponding period was estimated to be apparently decreasing. Our data indicate that the concentration of recalcitrant DRCs in the cormorant during 2001-2008 was scarcely affected by the national regulation on dioxins emission.
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Affiliation(s)
- Akira Kubota
- Center for Marine Environmental Studies, Ehime University, 2-5 Bunkyo-cho, Matsuyama 790-8577, Japan
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Krajka-Kuźniak V, Szaefer H, Ignatowicz E, Adamska T, Baer-Dubowska W. Beetroot juice protects against N-nitrosodiethylamine-induced liver injury in rats. Food Chem Toxicol 2012; 50:2027-33. [PMID: 22465004 DOI: 10.1016/j.fct.2012.03.062] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Revised: 03/16/2012] [Accepted: 03/17/2012] [Indexed: 01/27/2023]
Abstract
Red beetroot, a common ingredient of diet, is a rich source of a specific class of antioxidants, betalains. Our previous studies have shown the protective role of beetroot juice against carcinogen induced oxidative stress in rats. The aim of this study was to examine the effect of long term feeding (28 days) with beetroot juice on phase I and phase II enzymes, DNA damage and liver injury induced by hepatocarcinogenic N-nitrosodiethylamine (NDEA). Long term feeding with beetroot juice decreased the activities of enzymatic markers of cytochrome P450, CYP1A1/1A2 and CYP2E1. NDEA treatment also reduced the activities of these enzymes, but increased the activity of CYP2B. Moreover, combined treatment with beetroot juice and NDEA enhanced significantly CYP2B only. Modulation of P450 enzyme activities was accompanied by changes in the relevant proteins levels. Increased level and activity of NQO1 was the most significant change among phase II enzymes. Beetroot juice reduced the DNA damage increased as the result of NDEA treatment, as well as the biomarkers of liver injury. Collectively, these results confirm the protective effect of beetroot juice against oxidative damage shown in our previous studies and indicate that metabolic alterations induced by beetroot feeding may protect against liver damage.
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Murtomaa-Hautala M, Korkalainen M, Pelkonen O, Hegde N, Pohjanvirta R, Huitu O, Henttonen H, Rautio A, Viitala P, Viluksela M. Significant interspecies differences in induction profiles of hepatic CYP enzymes by TCDD in bank and field voles. Environ Toxicol Chem 2012; 31:663-671. [PMID: 22213473 DOI: 10.1002/etc.1737] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2011] [Revised: 09/22/2011] [Accepted: 11/09/2011] [Indexed: 05/31/2023]
Abstract
The gene expression and induction of cytochrome P450 (CYP)-enzymes following 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) peroral administration was studied in the livers of two wild vole species--the bank vole (Myodes glareolus) and the field vole (Microtus agrestis). The dioxin-sensitive C57BL/6 mouse was used as a reference. Doses of 0.05, 0.5, 5.0, and 50 µg/kg were applied to ascertain a dose-response relationship, and the dose of 50 µg/kg was applied to the study time course for up to 96 h. The cytochrome P450 1A1 (CYP1A1) mRNA expression showed an expected dose-dependent increase equally in both vole species. Bank voles expressed notably higher CYP2A mRNA levels as compared with field voles. Both species exhibited dose-dependent increases in putative CYP1A-, CYP2B-, and CYP2A-associated activities as measured by fluorometric assays for ethoxyresorufin-O-deethylase (EROD), penthoxyresorufin-O-depenthylase (PROD), and 7-ethoxycoumarin-O-deethylase (ECOD), respectively. Putative CYP2A-associated coumarin-7-hydroxylase (COH) activity showed a slight increase at the two highest doses of TCDD in field voles but not in bank voles, and their basal COH activity was only one-fourth or less of that in field voles. Overall, however, bank voles tended to exhibit higher CYP-associated enzyme activities measured at the two largest doses of TCDD than field voles. A western blot analysis of aryl hydrocarbon receptor (AhR) revealed that the two vole species had differential band patterns, suggesting dissimilar structures for their AhRs.
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Kravchenko LV, Aksenov IV, Trusov NV, Guseva GV, Avren'eva LI. [Effects of dietary fat level on the xenobiotic metabolism enzymes activity and antioxidant enzymes in rats]. Vopr Pitan 2012; 81:24-29. [PMID: 22642161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Male Wistar rats received fat-free diet or diets containing 5, 10 and 30% of fat (sunflower oil + lard, 1:1) for 4 weeks. The direct relationship between dietary fat level and ethoxyresorufin O-dealkylase activity of CYP1A1, methoxyresorufin O-dealkylase activity of CYP1A2, pentoxyresorufin O-dealkylase activity of CYP2B1 and testosterone 6beta-hydroxylase activity of CYP3A was found. Activities of key enzymes of phase II xenobiotic metabolism (total activity of glutathione transferase, activity of UDP-glucuronosyle transferase) and antioxidant enzymes (catalase, glutathione peroxidase, glutathione reductase, paraoxonase-1 and heme oxygenase-1) also increased with higher dietary fat level.
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Lu Z, Wong CS. Factors affecting phase I stereoselective biotransformation of chiral polychlorinated biphenyls by rat cytochrome P-450 2B1 isozyme. Environ Sci Technol 2011; 45:8298-8305. [PMID: 21863805 DOI: 10.1021/es200673q] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
In vitro incubations of rat cytochrome P-450 (CYP) 2B1 isozyme with three chiral polychlorinated biphenyl (PCB) congeners (PCBs 45, 95, and 132) were performed to investigate factors affecting phase I stereoselective biotransformation. Rat CYP2B1 preferentially biotransformed the second-eluting atropisomers of PCBs 45 and 95 at low substrate concentration ranges (≤15 μM). Biotransformation competition by different congeners was also observed, with increasing competition at higher chlorination. Competition decreased the biotransformation rates of each congener stereoselectively, affecting atropisomeric composition. No atropisomeric enrichment was observed for PCB 132 upon incubation of the racemate. However, under the same conditions, significant differences in biotransformation kinetics were observed in individual atropisomer incubations, indicating that (+)-PCB 132 and (-)-PCB 132 were competitively biotransformed. Homology modeling and docking studies suggested that each atropisomer had different interactions with rat CYP2B1 and could dock with the isozyme at different locations. This is one possible explanation for stereoselective biotransformation and competition of chiral PCBs at the molecular level. Our results suggest that the lack of predictive capability for stereoselectivity of PCBs and other chiral pollutants in biota may be due to competitive and/or inhibitory activities of different substrates, including individual enantiomers of the same compound.
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Affiliation(s)
- Zhe Lu
- Department of Chemistry, University of Manitoba , Winnipeg, Manitoba R3T 2N2, Canada
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Cooper HLR, Groves JT. Molecular probes of the mechanism of cytochrome P450. Oxygen traps a substrate radical intermediate. Arch Biochem Biophys 2011; 507:111-8. [PMID: 21075070 PMCID: PMC3041850 DOI: 10.1016/j.abb.2010.11.001] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2010] [Revised: 11/05/2010] [Accepted: 11/05/2010] [Indexed: 01/05/2023]
Abstract
The diagnostic substrate tetramethylcyclopropane (TMCP) has been reexamined as a substrate with three drug- and xenobiotic-metabolizing cytochrome P450 enzymes, human CYP2E1, CYP3A4 and rat CYP2B1. The major hydroxylation product in all cases was the unrearranged primary alcohol along with smaller amounts of a rearranged tertiary alcohol. Significantly, another ring-opened product, diacetone alcohol, was also observed. With CYP2E1 this product accounted for 20% of the total turnover. Diacetone alcohol also was detected as a product from TMCP with a biomimetic model catalyst, FeTMPyP, but not with a ruthenium porphyrin catalyst. Lifetimes of the intermediate radicals were determined from the ratios of rearranged and unrearranged products to be 120, 13 and 1ps for CYP2E1, CYP3A4 and CYP2B1, respectively, corresponding to rebound rates of 0.9×10(10)s(-1), 7.2×10(10)s(-1) and 1.0×10(12)s(-1). For the model iron porphyrin, FeTMPyP, a radical lifetime of 81ps and a rebound rate of 1.2×10(10)s(-1) were determined. These apparent radical lifetimes are consistent with earlier reports with a variety of CYP enzymes and radical clock substrates, however, the large amounts of diacetone alcohol with CYP2E1 and the iron porphyrin suggest that for these systems a considerable amount of the intermediate carbon radical is trapped by molecular oxygen. These results add to the view that cage escape of the intermediate carbon radical in [Fe(IV)-OH ()R] can compete with cage collapse to form a C-O bond. The results could be significant with regard to our understanding of iron-catalyzed C-H hydroxylation, the observation of P450-dependent peroxidation and the development of oxidative stress, especially for CYP2E1.
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Affiliation(s)
| | - John T. Groves
- Department of Chemistry, Princeton University, Princeton NJ 08544 USA
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Spearow JL, Kota RS, Ostrach DJ. Environmental contaminant effects on juvenile striped bass in the San Francisco Estuary, California, USA. Environ Toxicol Chem 2011; 30:393-402. [PMID: 21038432 DOI: 10.1002/etc.386] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The decline of pelagic organisms in the San Francisco Estuary (SFE) (California, USA) is attributed to several factors, including water diversions, invasive species, and exposure to environmental toxicants. The present study evaluated the effects of environmental contaminants on liver vitellogenin, metallothionein, 7-ethoxyresorufin-O-deethylase (EROD), and benzyloxyresorufin O-deethylase (BROD) activity in juvenile striped bass (Morone saxitilis) in the SFE. Analysis of juvenile striped bass liver extracts revealed site-specific elevations of vitellogenin, metallothionein, and EROD biomarkers across the estuary. Although some striped bass in the estuary showed EROD activity similar to unhandled hatchery controls, several sites in the estuary showed significantly higher EROD activity that was in the range of beta-naphthoflavone (BNF)-injected, positive controls. Overall, EROD activity averaged 283% higher in estuary fish than in hatchery controls. Chemical analyses of extracts from semipermeable membrane devices (SPMDs) deployed in the estuary for one month showed elevated polyaromatic hydrocarbon (PAH) levels. Semipermeable membrane devices extract injections-induced metallothionein and BROD in striped bass livers. These data show that environmental exposures are impacting EROD and other biomarkers in the SFE striped bass population. Previous studies in our laboratory have associated poor larval development with maternal transfer of environmental contaminants. Further studies are needed to monitor contaminant exposures by the use of biomarkers and to integrate them into a more effective pelagic species recovery plan in the SFE.
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Affiliation(s)
- Jimmy L Spearow
- Pathobiology, Conservation and Population Biology Laboratory, University of California Davis, California, USA
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Abstract
CONTEXT Byrsocarpus coccineus Schum. and Thonn. (Connaraceae) is a scandent shrub widely employed as a medicinal remedy for various disease conditions in West Africa. OBJECTIVE This study evaluated fractions of B. coccineus for modulation of cytochrome P450 (CYP) enzyme activity, cytokine production, and proliferation. MATERIALS AND METHODS The BROD (benzyloxyresorufin O-debenzylase) and BFCOD (benzyloxy-4-[trifluoromethyl]-coumarin O-debenzyloxylase) assays were used to evaluate effect on CYP2B1/2 and CYP3A4 enzyme activity. Effects on cytokine production and proliferation of HT29 cells were investigated using interferon expression assay and MTT (3-3[4,5-dimethyl-2-thiazolyl]-2-5-diphenyl-2H-tetrazolium bromide) assay, respectively. RESULTS Fractions derived from the organic solvent extraction of B. coccineus produced significant (p<0.05) stimulation of human hepatic CYP2B1/2 activity in the BROD assay. The greatest effects were elicited at 1 ng/mL corresponding to ∼ 3-fold stimulation of enzyme activity. Enhancement of CYP3A4 enzyme activity was also observed in the BFCOD assay. Other fractions from the organic extract showed significant antiproliferative effects on HT29 cells at 100 μg/mL. Fractions obtained from the aqueous extract of B. coccineus (1 µg/µL) significantly stimulated the expression of IFNα2a and IFNβ in peripheral blood mononuclear cells (PBMC), causing a maximum 26-fold increase of IFNα2a-transcript. DISCUSSION AND CONCLUSION The effect on CYP suggests that B. coccineus may reduce the therapeutic efficacy of co-administered drugs. This justifies the need for proper education of patients by healthcare practitioners on the outcomes of drug-herb interactions. This study identifies several in vitro activities that could underlie the attributed uses of this plant in traditional African medicine (TAM).
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Affiliation(s)
- Abidemi J Akindele
- Department of Pharmacology, Faculty of Basic Medical Sciences, College of Medicine, University of Lagos, Lagos, Nigeria.
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Liao T, Yang F, Hui Y, Cheng W, Xiong G, Jin S, Wang J, Xu Y. Multi-endpoint toxicities on Chinese rare minnow (Gobiocypris rarus) fed with different diets. Environ Toxicol Pharmacol 2011; 31:70-78. [PMID: 21787671 DOI: 10.1016/j.etap.2010.09.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2009] [Revised: 07/30/2010] [Accepted: 09/04/2010] [Indexed: 05/31/2023]
Abstract
To compare the effects of three diets, rare minnow was fed with three diets from 30 dph to mature period. The activities of EROD, PROD, SOD and GST were measured in the WBHs as well as Vtg and TBARS concentrations at 60 dph. The rest fish were fed until adulthood for breeding studies. The group A served as the control group. It was found that Vtg, GST and EROD were significantly increased in the groups B and C, but SOD, TBARS and PROD levels were significantly increased only in the group C. In the adulthood, Vtg was significantly induced in the males in the group C. In generation F1, inhibition of CAT D activities and decrease of reproductive success were only found in pellet A group, but not in pellet B group. These findings indicate that the selection of diet is extremely important to assure veracity of the experiment results.
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Affiliation(s)
- Tao Liao
- Institute for Farm Products Processing and Nuclear-Agricultural Technology, Hubei Academy of Agricultural Sciences, Hubei Innovation Center of Agricultural Science and Technology, 8# Nanhu YaoYuan Road, Wuhan 430064, China
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32
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Liu H, Tian N, Arany I, Bigler SA, Waxman DJ, Shah SV, Baliga R. Cytochrome P450 2B1 mediates complement-dependent sublytic injury in a model of membranous nephropathy. J Biol Chem 2010; 285:40901-10. [PMID: 20947506 PMCID: PMC3003390 DOI: 10.1074/jbc.m110.165498] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2010] [Revised: 09/27/2010] [Indexed: 11/06/2022] Open
Abstract
Membranous nephropathy is a disease that affects the filtering units of the kidney, the glomeruli, and results in proteinuria accompanied by loss of kidney function. Passive Heymann nephritis is an experimental model that mimics membranous nephropathy in humans, wherein the glomerular epithelial cell (GEC) injury induced by complement C5b-9 leads to proteinuria. We examined the role of cytochrome P450 2B1 (CYP2B1) in this complement-mediated sublytic injury. Overexpression of CYP2B1 in GECs significantly increased the formation of reactive oxygen species, cytotoxicity, and collapse of the actin cytoskeleton following treatment with anti-tubular brush-border antiserum (anti-Fx1A). In contrast, silencing of CYP2B1 markedly attenuated anti-Fx1A-induced reactive oxygen species generation and cytotoxicity with preservation of the actin cytoskeleton. Gelsolin, which maintains an organized actin cytoskeleton, was significantly decreased by complement C5b-9-mediated injury but was preserved in CYP2B1-silenced cells. In rats injected with anti-Fx1A, the cytochrome P450 inhibitor cimetidine blocked an increase in catalytic iron and ROS generation, reduced the formation of malondialdehyde adducts, maintained a normal distribution of nephrin in the glomeruli, and provided significant protection at the onset of proteinuria. Thus, GEC CYP2B1 contributes to complement C5b-9-mediated injury and plays an important role in the pathogenesis of passive Heymann nephritis.
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Affiliation(s)
- Hua Liu
- From the Departments of Pediatrics and
| | - Niu Tian
- From the Departments of Pediatrics and
| | | | - Steven A. Bigler
- Pathology, University of Mississippi Medical Center, Jackson, Mississippi 39216
| | - David J. Waxman
- the Division of Cell and Molecular Biology, Department of Biology, Boston University, Boston, Massachusetts 02215, and
| | - Sudhir V. Shah
- the Division of Nephrology, Department of Internal Medicine, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205
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Della Torre C, Corsi I, Nardi F, Perra G, Tomasino MP, Focardi S. Transcriptional and post-transcriptional response of drug-metabolizing enzymes to PAHs contamination in red mullet (Mullus barbatus, Linnaeus, 1758): a field study. Mar Environ Res 2010; 70:95-101. [PMID: 20417960 DOI: 10.1016/j.marenvres.2010.03.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2009] [Revised: 03/18/2010] [Accepted: 03/25/2010] [Indexed: 05/29/2023]
Abstract
Aim of this study was to evaluate the responsiveness of red mullet (Mullus barbatus) liver detoxification enzymes to PAHs at transcriptional and post-transcriptional levels in the field. Fish were captured in the north-eastern Adriatic Sea, close to an oil refinery. Sixteen PAHs (EPA) were determined in sediments and fish fillets; transcription levels of cyp1a, cyp3a and abcc2 genes and EROD, BROD, B(a)PMO, BFCOD, GST and UDPGT enzymatic activities were measured. Levels of PAHs in sediments reflect the oil pollution gradient of the area, with weak correspondence in fish fillets. cyp1a gene transcription and EROD, B(a)PMO and BFCOD activities were significantly induced in the oil refinery site, and a slight up-regulation of cyp3a and abcc2 was also observed. GST and UDPGT remained unchanged. The present study provides the first data on detoxification responses at transcriptional levels in the liver of red mullet and confirms phase I enzymes as suitable biomarkers of exposure to PAHs in field studies.
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Affiliation(s)
- Camilla Della Torre
- Department of Environmental Sciences "G. Sarfatti", University of Siena, Via Mattioli 4, 53100 Siena, Italy.
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Khokhar JY, Miksys SL, Tyndale RF. Rat brain CYP2B induction by nicotine is persistent and does not involve nicotinic acetylcholine receptors. Brain Res 2010; 1348:1-9. [PMID: 20599831 DOI: 10.1016/j.brainres.2010.06.035] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2010] [Revised: 05/06/2010] [Accepted: 06/15/2010] [Indexed: 11/19/2022]
Abstract
CYP2B is a drug-metabolizing enzyme expressed in the liver and brain that metabolizes a variety of centrally acting drugs (e.g. propofol, bupropion and nicotine), endogenous neurochemicals (e.g. serotonin and testosterone) and toxins (e.g. chlorpyrifos). Human CYP2B6 is found at higher levels in the brains of smokers, and 7-day nicotine treatment induces rat brain CYP2B while not altering hepatic CYP2B. We characterized the time course of rat brain CYP2B induction by nicotine and determined if nicotinic acetylcholine receptors (nAChRs) mediated this induction. Rats were treated once daily with 1mg/kg nicotine base or saline s.c. for 1 or 7days and sacrificed from 30minutes to 7days after the last injection. One-day nicotine treatment did not induce brain CYP2B, whereas 7-day nicotine treatment significantly increased CYP2B expression for up to 24hours in the frontal cortex and brainstem; these levels returned to baseline by 7days post-treatment. CYP2B activity was also higher at 24hours in these regions. No change was seen in the cerebellar CYP2B levels or in vivo activity following nicotine treatment. Time of day of treatment and sacrifice altered the magnitude of brain CYP2B induction while chlorisondamine, an irreversible nAChR blocker, pre-treatment did not block CYP2B induction. Seven-day nicotine treatment resulted in an induction of rat brain CYP2B protein and in vivo activity for up to 24hours, which would suggest greater local drug metabolism by brain CYP2B. Humans or animals exposed to nicotine may have altered therapeutic drug response, brain levels of neurotransmitters and/or neurotoxicity.
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Affiliation(s)
- Jibran Y Khokhar
- Centre for Addiction and Mental Health (CAMH), Toronto, and Departments of Pharmacology and Toxicology and Psychiatry, University of Toronto, Toronto, Ontario, Canada
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Oberg M, Westerholm E, Fattore E, Stern N, Hanberg A, Haglund P, Wiberg K, Bergendorff A, Håkansson H. Toxicity of Bromkal 70-5DE, a technical mixture of polybrominated diphenyl ethers, following 28 d of oral exposure in rats and impact of analysed impurities. Chemosphere 2010; 80:137-143. [PMID: 20447676 DOI: 10.1016/j.chemosphere.2010.04.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2009] [Revised: 02/26/2010] [Accepted: 04/02/2010] [Indexed: 05/29/2023]
Abstract
The subacute toxicity of a commercial polybrominated diphenyl ether (PBDE) preparation, Bromkal 70-5DE, was investigated. In addition to a vehicle control, the mixture was given orally to male and female Sprague-Dawley rats for 28 d at three dose levels; 2.5, 25 and 250 mg kg(-1) b.w.d(-1). The observed effects include increased hepatic EROD activity (from 2.5 mg kg(-1)d(-1)); increased liver weight (males), increased PROD activity and depletion of hepatic retinoids (from 25 mg kg(-1)d(-1)); and increased liver weight (females), marked histological changes in the liver and lungs, as well as increased serum parameters such as total protein, cholesterol and albumin (from 250 mg kg(-1)d(-1)). Chemical analysis of the PBDE mixture with gas chromatography/mass spectrometry (GS/MS) showed impurities of polybrominated dibenzofurans and to a lesser extent dibenzodioxins, in total levels of about 7.0 microg g(-1) of Bromkal technical mixture. The animals were thereby exposed to an estimated dose of dioxin-like equivalents corresponding to 1.3-131 ng TEQ kg(-1) b.w.d(-1). It cannot be ruled out that this level of impurities can explain the hepatic EROD induction and hepatic retinoid depletion, which are considered typical markers of toxicity mediated via the aryl hydrocarbon receptor (AhR).
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Affiliation(s)
- Mattias Oberg
- Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
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36
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Mustacich DJ, Leonard SW, Patel NK, Traber MG. Alpha-tocopherol beta-oxidation localized to rat liver mitochondria. Free Radic Biol Med 2010; 48:73-81. [PMID: 19819327 PMCID: PMC2818260 DOI: 10.1016/j.freeradbiomed.2009.10.024] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2009] [Revised: 09/21/2009] [Accepted: 10/04/2009] [Indexed: 12/14/2022]
Abstract
Approximately 40% of Americans take dietary supplements, including vitamin E (alpha-tocopherol). Unlike other fat-soluble vitamins, alpha-tocopherol is not accumulated to toxic levels. Rather tissue levels are tightly regulated, in part via increased hepatic metabolism and excretion that could, theoretically, alter metabolism of drugs, environmental toxins, and other nutrients. To date, in vivo subcellular location(s) of alpha-tocopherol metabolism have not been identified. The proposed pathway of alpha-tocopherol metabolism proceeds via omega-hydroxylation to 13'-OH-alpha-tocopherol, followed by successive rounds of beta-oxidation to form alpha-CEHC. To test the hypothesis that alpha-tocopherol omega-hydroxylation occurs in microsomes while beta-oxidation occurs in peroxisomes, rats received daily injections of vehicle, 10 mg alpha-tocopherol, or 10 mg trolox/100 g body wt for 3 days, and then microsomes, mitochondria, and peroxisomes were isolated from liver homogenates. Homogenate alpha-tocopherol levels increased 16-fold in alpha-tocopherol-injected rats, while remaining unchanged in trolox- or vehicle-injected rats. Total alpha-tocopherol recovered in the three subcellular fractions represented 93+/-4% of homogenate alpha-tocopherol levels. In alpha-tocopherol-injected rats, microsome alpha-tocopherol levels increased 28-fold, while mitochondria and peroxisome levels increased 8- and 3-fold, respectively, indicating greater partitioning of alpha-tocopherol to the microsomes with increasing liver alpha-tocopherol. In alpha-tocopherol-injected rats, microsome 13'-OH-alpha-tocopherol levels increased 24-fold compared to controls, and were 7-fold greater than 13'-OH-alpha-tocopherol levels in peroxisome and mitochondrial fractions of alpha-tocopherol-injected rats. An unexpected finding was that alpha-CEHC, the end product of alpha-tocopherol metabolism, was found almost exclusively in mitochondria. These data are the first to indicate a mitochondrial role in alpha-tocopherol metabolism.
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Affiliation(s)
- Debbie J Mustacich
- Linus Pauling Institute, 571 Weniger Hall, Oregon State University, Corvallis, OR 97331, USA.
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Brausch JM, Blackwell BR, Beall BN, Caudillo C, Kolli V, Godard-Codding C, Cox SB, Cobb G, Smith PN. Effects of polycyclic aromatic hydrocarbons in northern bobwhite quail (Colinus virginianus). J Toxicol Environ Health A 2010; 73:540-551. [PMID: 20391134 DOI: 10.1080/15287390903566559] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Polycyclic aromatic hydrocarbons (PAH) are ubiquitous contaminants of aquatic and terrestrial ecosystems, and are known to induce biochemical alterations in exposed organisms. Aside from a variety of adverse physiological effects associated with exposure to petroleum products, oils, and oil sludges, little is known about the effects of individual PAH on birds. Acute toxicity of naphthalene, pyrene, and benz[a]anthracene (BAA) was examined in adult northern bobwhite quail (Colinus virginianus). Additionally, subacute (8 d) and subchronic (60 d) studies were conducted to assess alterations in metabolic enzyme activity. Neither naphthalene, nor pyrene, nor BAA exposure via oral gavage produced acute toxicity up to the limit dose of 2 g/kg body weight. In the subacute study, quail provided feed containing the highest concentration of BAA for 5 d had significantly increased renal ethoxyresorufin O-deeththylase (EROD) activity compared to controls. Following a 3-d recovery period, significant increases between 10 and 100 mg/kg of BAA in feed existed for both hepatic EROD and pentoxyresorufin O-deethylase (PROD) activity compared to controls. Subchronic exposure to BAA (ranging from 0.1 to 10 mg/kg) also resulted in a significant rise of EROD and PROD in both kidney and liver tissue compared to controls. Though the individual PAH used in this study were not acutely toxic, these results confirm that these individual PAH induce alterations in metabolic enzyme activity in northern bobwhite quail.
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Affiliation(s)
- John M Brausch
- Institute of Environmental and Human Health, Department of Environmental Toxicology, Texas Tech University, Lubbock, Texas, USA
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Barton HA, Tang J, Sey YM, Stanko JP, Murrell RN, Rockett JC, Dix DJ. Metabolism of myclobutanil and triadimefon by human and rat cytochrome P450 enzymes and liver microsomes. Xenobiotica 2009; 36:793-806. [PMID: 16971344 DOI: 10.1080/00498250600821292] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Metabolism of two triazole-containing antifungal azoles was studied using expressed human and rat cytochrome P450s (CYP) and liver microsomes. Substrate depletion methods were used due to the complex array of metabolites produced from myclobutanil and triadimefon. Myclobutanil was metabolized more rapidly than triadimefon, which is consistent with metabolism of the n-butyl side-chain in the former and the t-butyl group in the latter compound. Human and rat CYP2C and CYP3A enzymes were the most active. Metabolism was similar in microsomes prepared from livers of control and low-dose rats. High-dose (115 mg kg-1 day-1 of triadimefon or 150 mg kg-1 day-1 of myclobutanil) rats showed increased liver weight, induction of total CYP, and increased metabolism of the two triazoles, though the apparent Km appeared unchanged relative to the control. These data identify CYP enzymes important for the metabolization of these two triazoles. Estimated hepatic clearances suggest that CYP induction may have limited impact in vivo.
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Affiliation(s)
- H A Barton
- National Center for Computational Toxicology, Office of Research and Development, US Environmental Protection Agency, Research Triangle Park, NC 27711, USA.
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Parente TEM, De-Oliveira ACAX, Beghini DG, Chapeaurouge DA, Perales J, Paumgartten FJR. Lack of constitutive and inducible ethoxyresorufin-O-deethylase activity in the liver of suckermouth armored catfish (Hypostomus affinis and Hypostomus auroguttatus, Loricariidae). Comp Biochem Physiol C Toxicol Pharmacol 2009; 150:252-60. [PMID: 19460462 DOI: 10.1016/j.cbpc.2009.05.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2009] [Revised: 05/07/2009] [Accepted: 05/08/2009] [Indexed: 11/21/2022]
Abstract
We investigated the presence and inducibility of CYP1A in suckermouth catfish (Hypostomus affinis and Hypostomus auroguttatus, Loricariidae), tilapia (Oreochromis niloticus, Cichlidae) and mice (Mus musculus, Muridae). Alkoxyresorufin-O-dealkylases (EROD, MROD, PROD and BROD) were detected and proved to be inducible (beta-naphthoflavone, BNF or dimethylbenz[a]anthracene, DMBA, 50 mg/kg bw ip) in liver microsomes from tilapia and mice. In loricariids, alkoxyresorufin-O-dealkylases were either undetectable (MROD/EROD) or very low (PROD/BROD), and so they remained after treatment with BNF or DMBA. Ethoxycoumarin-O-deethylase (ECOD) was recorded in all species and proved not to be inducible by BNF or DMBA. In loricariids and tilapia, ECOD was not depressed by a concentration of alpha-naphthoflavone (CYP1A-inhibitor) that markedly depressed EROD in tilapia. A CYP1A-like protein was detected by a monoclonal antibody in rats, mice and tilapia, but not in loricariids. A polyclonal antibody, however, detected a CYP1A-like protein in liver microsomes of loricariids. Suckermouth catfish, rats, mice and tilapia express a protein reactive with a polyclonal antibody against trout CYP3A. Loricariids and tilapia exhibited marked genotoxic responses (enhanced incidence of micronucleated erythrocytes) following treatment DMBA (50 mg/kg bw ip), a promutagen activated by CYP1A/1B. Therefore, although not exhibiting EROD, a CYP1A-mediated activity, loricariids converted DMBA into its genotoxic metabolites. Our findings suggest that the CYP1A-like protein of locariid catfish recognizes DMBA, but not ethoxyresorufin, as a substrate.
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Affiliation(s)
- T E M Parente
- Laboratory of Environmental Toxicology, Department of Biological Sciences, National School of Public Health, Av Brasil 4036 (EXCAM), Rio de Janeiro, RJ 21040-361, Brazil
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Warner NA, Martin JW, Wong CS. Chiral polychlorinated biphenyls are biotransformed enantioselectively by mammalian cytochrome P-450 isozymes to form hydroxylated metabolites. Environ Sci Technol 2009; 43:114-21. [PMID: 19209593 DOI: 10.1021/es802237u] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
In vitro incubations of purified rat cytochrome P-450 (CYP) 2B1 and human CYP 2B6 were performed to determine if CYP isozymes biotransform polychlorinated biphenyls (PCBs) enantioselectively. Enantioselective metabolism of chiral PCBs 45, 84, 91, 95, 132, and 136 and production of hydroxylated PCB metabolites (OH-PCBs) were observed, while no changes in PCB 183 atropisomer composition were observed for either isozyme. Enantiomer fractions (EFs) of parent PCBs, individually incubated as racemates at 25 ng/mL initial concentration, with rat CYP 2B1 ranged from 0.353 to 0.822. Enantioselectivity was also observed for PCBs 45 (EF = 0.437) and 132 (EF = 0.537) incubated at that concentration with human CYP 2B6. Both atropisomers of chiral PCBs appeared to be biotransformed simultaneously by rat CYP 2B1, except for (+)-PCB 132, but at different rates. Hydroxylated PCBs were identified using gas chromatography-high resolution mass spectrometry for all chiral PCBs enantioselectively transformed by CYPs. These metabolites did not correspond to any commercially available authentic standards, supporting the hypothesis that many unidentified OH-PCBs detected in wildlife may have arisen from in vivo biotransformation of chiral PCBs. A rough estimate suggested that more than half of the total congener metabolized by rat CYP 2B1 was converted to OH-PCBs. Similar concentration decreases were observed for congeners incubated with human CYP 2B6, but less OH-PCBs were formed. Formation of OH-PCBs via an enantioselective OH insertion mechanism was suggested, and may be a source of the unidentified OH-PCBs currently found in the environment.
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Affiliation(s)
- Nicholas A Warner
- Polar Environmental Centre, Norwegian Institute of Air Research, Tromsø NO-9296, Norway
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Haduch A, Wójcikowski J, Daniel WA. Effect of selected antidepressant drugs on cytochrome P450 2B (CYP2B) in rat liver. An in vitro and in vivo study. Pharmacol Rep 2008; 60:957-965. [PMID: 19211989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2008] [Revised: 12/05/2008] [Indexed: 05/27/2023]
Abstract
The aim of the present study was to investigate the influence of antidepressants with different chemical structures and mechanisms of action affecting serotonergic and/or noradrenergic systems - tricyclic antidepressant drugs (TAD), selective serotonin reuptake inhibitors (SSRIs) and novel antidepressants (mirtazapine, nefazodone) - on the activity of rat CYP2B measured as the rate of 16beta-hydroxylation of testosterone. The reaction was studied in control liver microsomes in the presence of antidepressants, as well as in microsomes of rats treated intraperitoneally for one day or two weeks (twice a day) with pharmacological doses (mg/kg) of the drugs (imipramine, amitriptyline, clomipramine, nefazodone 10; desipramine, fluoxetine, sertraline 5; mirtazapine 3). The obtained K(i) values indicated that nefazodone and the SSRIs sertraline and fluoxetine were the most potent inhibitors of the studied reaction (K(i) = 10-20 microM). The inhibitory effects of TADs were modest (K(i) = 62-85 microM), while mirtazapine was a very weak inhibitor of CYP2B activity (K(i) = 286 microM). After a one-day exposure of rats to the investigated antidepressants, a significant increase in CYP2B activity was only observed after sertraline exposure (300% of the control). Chronic treatment with the antidepressants led to a significant enhancement of CYP2B activity after sertraline, fluoxetine and desipramine (580, 200 and 150% of the control, respectively) treatment, which positively correlated with the observed elevation in CYP2B protein levels. In summary, two different mechanisms of the antidepressant-CYP2B interaction are postulated: 1) a direct inhibition of CYP2B shown in vitro by nefazodone, SSRIs and TADs; 2) in vivo induction of CYP2B produced by prolonged administration of SSRIs and desipramine, which suggests their influence on enzyme regulation. The marked CYP2B-induction produced by SSRIs corresponds with their selective serotonin reuptake inhibition, while the effect of desipramine corresponds with its selective inhibition of noradrenaline reuptake.
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Affiliation(s)
- Anna Haduch
- Department of Pharmacokinetics and Drug Metabolism, Institute of Pharmacology, Polish Academy of Sciences, Smetna 12, PL 31-343 Kraków, Poland
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Della Torre C, Corsi I, Arukwe A, Valoti M, Focardi S. Interactions of 2,4,6-trinitrotoluene (TNT) with xenobiotic biotransformation system in European eel Anguilla anguilla (Linnaeus, 1758). Ecotoxicol Environ Saf 2008; 71:798-805. [PMID: 18407354 DOI: 10.1016/j.ecoenv.2008.03.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2007] [Revised: 02/29/2008] [Accepted: 03/01/2008] [Indexed: 05/26/2023]
Abstract
The aim of the present study was to investigate the interaction of 2,4,6-trinitrotoluene (TNT) with liver biotransformation enzymes in European eel Anguilla anguilla (Linnaeus, 1758). Eels were exposed to 0.5, 1 and 2.5mg/l nominal concentrations of TNT for 6 and 24h. Modulation of CYP1A1, UDPGT and GST genes was investigated by real-time PCR. Total CYP450 content, NADPH cytochrome c reductase activity, CYP1A and CYP2B-like activities, such as EROD, MROD and BROD, as well as GST and UDPGT activities, were measured by biochemical assays. An in vitro study was performed on EROD in order to evaluate catalytic modulation by TNT. No modulation of the CYP1A1 gene or protein was observed in TNT-exposed eels. On the other hand, a significant decline of EROD and MROD activities was observed in vivo. An increase in NADPH cyt c reductase, and phase II enzymes (UDPGT and GST) were observed at both gene expression and activity levels. The overall results indicated that TNT is a potential competitive inhibitor of CYP1A activities. A TNT metabolic pathway involving NADPH cyt c reductase and phase II enzymes is also suggested.
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Affiliation(s)
- Camilla Della Torre
- Department of Environmental Sciences G. Sarfatti, University of Siena, Via Mattioli 4, 53100 Siena, Italy.
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Hodek P, Bortek-Dohalská L, Sopko B, Sulc M, Smrcek S, Hudecek J, Janků J, Stiborová M. Structural requirements for inhibitors of cytochromes P450 2B: Assessment of the enzyme interaction with diamondoids. J Enzyme Inhib Med Chem 2008; 20:25-33. [PMID: 15895681 DOI: 10.1080/14756360400024324] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
The series of diamondoids: adamantane, diamantane, triamantane, 2-isopropenyl-2-methyladamantane and 3-isopropenyl-3-methyldiamantane (3-IPMDIA), were employed to elucidate the molecular basis of their interaction with the active site of cytochromes P450 (CYP) of a 2B subfamily. These potent inhibitors of CYP2B enzymes were docked into the homology model of CYP2B4. Apparent dissociation constants calculated for the complexes of CYP2B4 with docked diamandoids agreed closely with the experimental data showing inhibition potency of the compounds and their binding affinity to CYP2B4. Superimposed structures of docked diamondoids mapped binding site residues. As they are mainly non-polar residues, the hydrophobicity plays the major role in the binding of diamondoids. Overlapping structure of diamondoids defined an elliptical binding cavity (5.9A inner diameter, 7.9A length) forming an angle of approximately 43 degrees with the heme plane. CYP2B specific diamondoids, namely 3-IPMDIA, showing the highest binding affinity, should be considered for a potential clinical use.
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Affiliation(s)
- Petr Hodek
- Department of Biochemistry, Faculty of Science, Charles University, Hlavova 2030, Prague 2 CZ-12840, Czech Republic.
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Shaban Z, Soliman M, El-Shazly S, El-Bohi K, Abdelazeez A, Kehelo K, Kim HS, Muzandu K, Ishizuka M, Kazusaka A, Fujita S. AhR and PPARa: antagonistic effects on CYP2B and CYP3A, and additive inhibitory effects on CYP2C11. Xenobiotica 2008; 35:51-68. [PMID: 15788368 DOI: 10.1080/00498250400021804] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that mediates a spectrum of toxic and biological effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and related compounds. The peroxisome proliferator-activated receptor alpha (PPARalpha) is a member of the nuclear receptor super-family of ligand-activated transcription factors and it functions as an obligate heterodimer with retinoid X-receptor alpha RXRalpha. The aim was to investigate whether the negative cross-talk recently proposed by the present authors between AhR and PPARalpha on CYP4A and CYP1A has any impact on other cytochrome P450 enzymes. Treatment of male Wistar rats with a PPARalpha ligand clofibric acid (CA) induced CYP2B1/2 and CYP3A proteins, activities, and the mRNA expression of CYP2B1, CYP2B2, CYP3A1 and CYP3A2, and suppressed CYP2C11 protein, activities and mRNA expression. AhR ligand Sudan III (S.III) treatment decreased basal and CA-induced CYP2B, CYP3A and CYP2C11 protein, activities and mRNA expression. To the best of the authors' knowledge, this is the first study showing the presence of mutual effects of AhR and PPARalpha on CYP2B and CYP3A and an additive inhibitory effect on CYP2C11 in the livers of male rats.
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Affiliation(s)
- Z Shaban
- Laboratory of Toxicology, Department of Environmental Veterinary Sciences Graduate, School of Veterinary Medicine, Hokkaido University, Sapporo, Japan
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45
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Abstract
To determine the cytochrome P450 (CYP) primarily expressed after styrene exposure, seven forms of hepatic CYP mRNA in rats treated with 600 mg kg(-1) styrene were examined. CYP1A2, CYP2B1/2, CYP2E1 and CYP3A2 mRNA were observed using real-time LightCycler PCR. The amount of CYP2B1 mRNA was significantly increased, 47-fold compared with controls, suggesting that this CYP is the primary cytochrome P450 in rats exposed to styrene. Significant increases in the amount of CYP2E1, CYP1A2 and CYP2B2 mRNA were also observed after styrene exposure, and their increase levels were 3.1-, 1.7- and 1.7-fold higher than controls, respectively. Western blot analysis also indicated that the protein levels of CYP2B1, CYP2B2, CYP2E1 and CYP1A2 showed clear increases after styrene treatment, corresponding to their mRNA expression. CYP2C11 mRNA decreased significantly in rats after styrene exposure. CYP1A1 was detected at the mRNA level in rat liver, but it was not detected at the protein level. The expression of epoxide hydrolase (EH), involved in Phase I drug metabolism, was also examined. EH mRNA increased 2-fold compared with controls after styrene exposure. Styrene thus appears to be a chemical compound that induces multiple CYPs. The results demonstrate that CYP2B1 is the primarily induced CYP form by styrene treatment to rats at acute toxic level.
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Affiliation(s)
- F Hirasawa
- Department of Biochemistry, Akita University School of Medicine, Japan
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46
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Fry JR, Hammond AH, Jassi KL, Bass AE, Bruce G, Laughton C, Shaw PN, Bylov IE, Kovalenko SM. Selectivity of 7-alkoxycoumarins as probe substrates for rat hepatic cytochrome P450 forms is influenced by the substitution pattern on the coumarin nucleus. Xenobiotica 2008; 34:707-22. [PMID: 15690760 DOI: 10.1080/00498250400003463] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
1. The O-dealkylation of 7-alkoxycoumarins is widely used as an assay to characterize cytochrome P450 (CYP) activity. These substrates can also undergo oxidative attack at additional sites on the coumarin nucleus, which may influence their apparent selectivity for particular CYP forms. 2. Accordingly, the effect of blockade of these additional sites was investigated on the selectivity towards rat hepatic CYP forms, with emphasis on the CYP1A and 2B forms. 3. Blockade of the 3-/4- and 6-positions resulted in substrates for which the CYP1A1/2 selectivity of the unsubstituted 7-alkoxycoumarins was altered to a CYP2B selectivity; this was achieved with little overall change in the molecular dimensions of the substrate. Limited analysis of other inducible CYP forms indicated at most only small effects of structure modification on activity. 4. The findings suggest that the sensitivity of probe substrates for CYP forms may be limited by the occurrence of competing side reactions of the substrate, and that better probes may be derived by blocking the sites of these side reactions.
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Affiliation(s)
- J R Fry
- School of Biomedical Sciences, Medical School, Queen's Medical Centre, Nottingham NG7 2UH, UK.
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47
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Ringel M, Oesch F, Gerl M, Klebach M, Quint M, Bader A, Böttger T, Hengstler JG. Permissive and suppressive effects of dexamethasone on enzyme induction in hepatocyte co-cultures. Xenobiotica 2008; 32:653-66. [PMID: 12296987 DOI: 10.1080/00498250210144811] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
1. Steroids are known to act as permissive factors in hepatocytes. This study shows that dexamethasone (DEX) is a permissive factor for induction of CYP2B1/2, CYP3A1, CYP2A1 and probably also CYP2C11 in cultures with primary rat hepatocytes. 2. The induction factor of phenobarbital (PB)-induced formation of 16beta-hydroxytestosterone (OHT), a testosterone biotransformation product predominantly formed by CYP2B1, is increased 18-fold by the addition of 32 nM DEX to the culture medium. Interestingly, higher concentrations of DEX up to 1000 nM led to a concentration-dependent maximally 5-fold decrease (p = 0.002) of phenobarbital-induced 16beta-OHT formation compared with the effect observed with 32 nM DEX. Thus, DEX shows permissive and suppressive effects on enzyme induction depending on the concentration of the glucocorticoid. 3. Qualitatively similar but smaller permissive and suppressive effects of DEX were observed for PB-induced CYP3A1 activity as evidenced by formation of 2beta-, 6beta- and 15beta-OHT. 4. DEX is a permissive factor for induction of CYP2A1 activity by 3-methylcholanthrene (3MC), as evidenced by the formation of 7alpha-OHT. Without addition of DEX, 3MC did not induce formation of 7alpha-OHT, whereas an almost 3-fold induction occurred in the presence of DEX. In contrast to CYP2B and CYP3A, concentrations up to 1000 nM DEX were not suppressive for the induction of CYP2A1. 5. We described recently a technique that allows preparation of cultures from cryopreserved hepatocytes. An almost identical influence of dexamethasone on enzyme induction was observed here in cultures from cryopreserved compared with freshly isolated hepatocytes. 6. Cultures with primary hepatocyte cultures represent a well-established technique for the study of drug-drug interactions. However, a large interlaboratory variation is known. Our study provides evidence that differences in glucocorticoid concentration in the culture medium contribute to this variation.
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Affiliation(s)
- M Ringel
- Institute of Toxicology, Obere Zahlbacher Str. 67, D-55131 Mainz, Germany
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48
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Abstract
1. The metabolism of diallyl disulphide was investigated in vitro with rat and human liver cell subfractions and ex vivo with an isolated perfused rat liver. 2. Diallyl disulphide was oxidized to diallylthiosulphinate by rat liver microsomes with an apparent K(m) = 0.86 +/- 0.1 mM and an apparent V(max) = 0.47 +/- 0.12 nmol min(-1) mg(-1) protein (mean +/- SE). Both cytochrome P450 (CYP) and flavin-containing monooxygenases were involved, with CYP2B1/2 and CYP2E1 being the most active CYP enzymes. 3. In rat and man, microsomal oxidation of allylmethyl sulphide to allylmethyl sulphoxide and allylmethyl sulphone also occurred, although at a low rate. Diallyl disulphide was also metabolized to allylglutathione sulphide and allylmercaptan. In addition, diallylthiosulphinate reacted non-enzymatically with glutathione to form allylglutathione sulphide. 4. When an isolated rat liver was perfused with diallyl disulphide, the metabolites allyl mercaptan, allylmethyl sulphide, allylmethyl sulphoxide, allylmethyl sulphone and allylglutathione sulphide were detected primarily within the liver tissue, with only small amounts of metabolites found in the bile and perfusion medium. The pharmacokinetic parameters for diallyl disulphide were t(1/2) = 6.09 min; AUC(0- infinity ) = 4.77 min mmol l(-1); clearance = 34.22 ml min(-1). 5. A scheme for the metabolism of diallyl disulphide in rat and man is proposed.
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Affiliation(s)
- E Germain
- Unité Mixte de Recherche de Toxicologie Alimentaire, Institut National de Recherche Agronomique--Université de Bourgogne, Dijon Cedex, France
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49
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Wahl M, Lahni B, Guenther R, Kuch B, Yang L, Straehle U, Strack S, Weiss C. A technical mixture of 2,2',4,4'-tetrabromo diphenyl ether (BDE47) and brominated furans triggers aryl hydrocarbon receptor (AhR) mediated gene expression and toxicity. Chemosphere 2008; 73:209-215. [PMID: 18619640 DOI: 10.1016/j.chemosphere.2008.05.025] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2008] [Revised: 04/30/2008] [Accepted: 05/05/2008] [Indexed: 05/26/2023]
Abstract
Polybrominated diphenyl ethers (PBDE) are found as ubiquitous contaminants in the environment, e.g., in sediments and biota as well as in human blood samples and mother's milk. PBDEs are neuro- and developmental toxins, disturb the endocrine system and some are even carcinogenic. Structural similarities of PBDEs with dioxin-like compounds, e.g., 2,3,7,8-tetrachloro-dibenzodioxin (TCDD), have raised concern about a possible "dioxin-like" action of PBDEs. TCDD exerts its toxicity via binding to and activation of the aryl hydrocarbon receptor (AhR). AhR ligands are in contrast to PBDEs usually coplanar compounds. Thus, PBDEs are not likely to be strong AhR agonists. The aim of this study was to analyze the effects of the most abundant PBDE congener, 2,2',4,4'-tetrabromo diphenyl ether (BDE47), on AhR activity and signaling. Initially, we measured cytochrome P450 1A1 (Cyp1A1) induction as a readout for AhR activation by BDE47. Low grade purified BDE47 increased CYP1A1 levels in transformed and primary rat hepatocytes and human hepatoma cells. Chemical analysis of the BDE47 sample identified trace contaminations with brominated furans such as 2,3,7,8-tetrabromo dibenzodioxin (TBDF), which most likely were responsible for the observed activation of AhR. Subsequently, the BDE47 mixture was studied for its effect on AhR mediated toxicity and global gene expression. Indeed, in rat hepatoma cells and in zebrafish embryos the BDE47 mixture provoked changes in gene expression and toxicity similar to known AhR agonists. In addition to the dioxin-like actions, the BDE47 sample enhanced Cyp2B and Cyp3A expression suggesting that commercial PBDE mixtures, which also often contain brominated furans, may disturb cellular homeostasis at multiple levels.
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Affiliation(s)
- M Wahl
- Institute of Toxicology and Genetics (ITG), Research Center Karlsruhe (FZK), Hermann-von-Helmholtz-Platz 1, Eggenstein-Leopoldshafen, Germany
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50
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Marsili L, Casini S, Bucalossi D, Porcelloni S, Maltese S, Fossi MC. Use of immunofluorescence technique in cultured fibroblasts from Mediterranean cetaceans as new "in vitro" tool to investigate effects of environmental contaminants. Mar Environ Res 2008; 66:151-153. [PMID: 18396327 DOI: 10.1016/j.marenvres.2008.02.068] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The aim of the present study was to propose the immunofluorescence technique in cultured fibroblasts from Mediterranean cetaceans as a new "in vitro" tool to explore the susceptibility of these marine mammals to different xenobiotic compounds. The cell lines were cultured from integument biopsies of free-ranging and stranded cetaceans (dead within 12h). Using the indirect immunofluorescence assay, we detected endogenous proteins induced by different contaminants. Here we present the method used for qualitative and quantitative evaluation of cytochromes P450 (CYP1A1 and CYP2B) induced by some POPs (DDTs and PCBs) and emerging contaminants (PBDEs) in fibroblast cell cultures of striped dolphin (Stenella coeruleoalba) and bottlenose dolphin (Tursiops truncatus). Immunofluorescence was quantified with a specially designed Olympus macro, DetectIntZ. A major result was the possibility of using this "in vitro" assay to quantify induction of endogenous proteins.
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Affiliation(s)
- Letizia Marsili
- Department of Environmental Sciences G Sarfatti, Siena University, Via Mattioli 4, Siena, Italy.
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