RESUMEN
The NOD-like receptor family pyrin domain-containing protein 3 (NLRP3) inflammasome triggers the maturation of interleukin-1ß (IL-1ß) and is implicated in the pathogenesis of various inflammatory diseases. Urolithin A, a gut microbial metabolite of ellagic acid, reportedly exerts antiinflammatory effects in vitro and in vivo. However, whether urolithin A suppresses NLRP3 inflammasome activation is unclear. In this study, urolithin A inhibited the cleavage of NLRP3 inflammasome agonist-induced caspase-1, maturation of IL-1ß, and activation of pyroptosis in lipopolysaccharide-primed mouse bone marrow-derived macrophages. Urolithin A reduced generation of intracellular and mitochondrial reactive oxygen species (ROS) and restricted the interaction between thioredoxin-interacting protein and NLRP3, which attenuated NLRP3 inflammasome activation. Urolithin A administration prevented monosodium urate-induced peritonitis in mice. Collectively, these findings indicate that urolithin A suppresses NLRP3 inflammasome activation, at least partially, by repressing the generation of intracellular and mitochondrial ROS.
Asunto(s)
Cumarinas , Inflamasomas , Interleucina-1beta , Proteína con Dominio Pirina 3 de la Familia NLR , Peritonitis , Especies Reactivas de Oxígeno , Ácido Úrico , Animales , Proteína con Dominio Pirina 3 de la Familia NLR/metabolismo , Cumarinas/farmacología , Cumarinas/química , Especies Reactivas de Oxígeno/metabolismo , Peritonitis/tratamiento farmacológico , Peritonitis/metabolismo , Peritonitis/inducido químicamente , Ácido Úrico/metabolismo , Inflamasomas/metabolismo , Ratones , Interleucina-1beta/metabolismo , Macrófagos/efectos de los fármacos , Macrófagos/metabolismo , Ratones Endogámicos C57BL , Caspasa 1/metabolismo , Masculino , Mitocondrias/efectos de los fármacos , Mitocondrias/metabolismo , Lipopolisacáridos , Piroptosis/efectos de los fármacos , Proteínas Portadoras , TiorredoxinasRESUMEN
We investigated VEGF expression in the uterus during the estrous cycle in the golden hamster (Mesocricetus auratus). Reverse transcription polymerase chain reaction of genes expressed in the uterus revealed the presence of at least three different VEGF isoforms (hamster VEGF188, VEGF164, and VEGF120). They were highly homologous to the respective mouse and human isoforms. Furthermore, VEGF164 and VEGF120 were predominantly expressed in the hamster uterus during the estrous cycle. In situ hybridization revealed that VEGF is expressed only in the luminal and glandular epithelium of the endometrium but not in the stromal cells or myometrium. The positive reaction of luminal and glandular epithelial cells on day 4 of the estrous cycle (day 1 = day of ovulation) was a little stronger than that of other days of the cycle. These findings suggest that VEGF molecules are secreted by endometrial epithelial cells and play an important role in the maintenance of blood vessels in the endometrial stroma. These results also suggest that uterine changes, such as edema, observed from day 4 to day 1 of the estrous cycle, are expected to occur primarily through the action of VEGF secreted by the uterine endometrial epithelium in preparation for subsequent embryo implantation.
Asunto(s)
Útero , Factor A de Crecimiento Endotelial Vascular , Cricetinae , Femenino , Humanos , Animales , Ratones , Factor A de Crecimiento Endotelial Vascular/genética , Factor A de Crecimiento Endotelial Vascular/metabolismo , Mesocricetus , Útero/metabolismo , Factores de Crecimiento Endotelial Vascular/metabolismo , Endometrio/metabolismo , Ciclo Estral , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismoRESUMEN
Smoking is a risk factor for adult-onset Crohn's disease (CD). Although passive smoking from family members is a major concern, especially in pediatric CD, the number of existing epidemiological studies is limited. This multicenter case-control study aimed to assess the effects of familial smoking on pediatric CD. We examined 22 pediatric CD cases and 135 controls. The subjects' mothers were given a self-administered questionnaire about family smoking before disease onset in the CD group or the corresponding period in the control group. Univariable logistic regression model was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs), whereas dose-response relationship analyses were performed for more in-depth evaluations. Univariable analyses indicated that passive smoking from the mother (OR, 2.09; 95% CI, 0.61-7.10) was not a significant, but a candidate risk factor for developing pediatric CD. In contrast, the dose-response relationship analyses revealed that passive smoking from the mother (OR, 1.17; 95% CI, 1.04-1.31) was significantly associated with pediatric CD. Therefore, passive smoking from the mother may be predominantly associated with the development of pediatric CD. Further follow-up studies comprising environmental measurements of passive smoking exposure doses and genetic factors interaction analysis are necessary.
Asunto(s)
Enfermedad de Crohn/epidemiología , Madres , Fumar/efectos adversos , Contaminación por Humo de Tabaco/efectos adversos , Adulto , Estudios de Casos y Controles , Niño , Enfermedad de Crohn/etiología , Femenino , Humanos , Recién Nacido , Japón/epidemiología , Masculino , Embarazo , Efectos Tardíos de la Exposición Prenatal , Factores de Riesgo , Fumar/epidemiología , Contaminación por Humo de Tabaco/estadística & datos numéricosRESUMEN
Crohn's disease is one of the systemic autoimmune diseases. It commonly affects the small intestine and colon but may involve any portion of the gastrointestinal tract from the mouth to the anus. The most affected area by Crohn's disease is the distal part of the small intestine, in which the bile acid molecules are most efficiently reabsorbed. Bile acids form mixed micelles together with fatty acids, which function as a transport vehicle to deliver fatty acids to the apical membrane of enterocytes for absorption. Therefore, if the terminal ileum is impaired, bile acid malabsorption may occur, which may cause congenital diarrhoea in Crohn's disease. Similarly, the impairment of the terminal ileum also induces fatty acid malabsorption, which may influence the role of fatty acids in Crohn's disease. In contrast, a recent study reported that multidrug resistance protein 1 (MDR1) regulated effector T-cell function in the ileum from bile acid-driven oxidative stress and MDR1 loss of function in a subset of patients with Crohn's disease. However, the role of consumption of fatty acids in Crohn's disease remains to be fully elucidated. This review is aimed at providing an overview of some recent developments in research of Crohn's disease from comprehensive perspective with a focus on the connection between disease location and behaviour, lipid diets, and bile acid malabsorption.
Asunto(s)
Ácidos y Sales Biliares/metabolismo , Enfermedad de Crohn/metabolismo , Enterocitos/fisiología , Ácidos Grasos/metabolismo , Tracto Gastrointestinal/metabolismo , Metabolismo de los Lípidos , Linfocitos T/fisiología , Miembro 1 de la Subfamilia B de Casetes de Unión a ATP/genética , Animales , Enfermedad de Crohn/genética , Dieta , Tracto Gastrointestinal/patología , Humanos , Estrés OxidativoRESUMEN
Urolithin A, a gut microbial metabolite of ellagic acid, is reported to exert anti-inflammatory effects in vitro and in vivo. However, complete mechanisms underlying the regulation of inflammatory responses by urolithin A remain unclear. This study aimed to evaluate the anti-inflammatory potential of urolithin A and its underlying mechanisms in lipopolysaccharide (LPS)-stimulated RAW264 macrophages. Urolithin A significantly attenuated the pro-inflammatory mediator production in LPS-stimulated RAW264 and mouse peritoneal macrophages. This compound significantly suppressed the LPS-elicited nuclear factor-κB (NF-κB) and activator protein-1 (AP-1) activation. The phosphorylation of Akt and c-Jun N-terminal kinase (JNK) was also inhibited by the treatment with urolithin A. Through experiments using kinase inhibitors, urolithin A abolished the LPS-induced phosphatidylinositol 3-kinase (PI3-K)/Akt/NF-κB and JNK/AP-1 signaling pathways, resulting in suppression of pro-inflammatory mediator production. Furthermore, treatment with this compound significantly reduced the intracellular accumulation of reactive oxygen species, which are known to act as secondary messengers in the activation of redox-sensitive transcription factors NF-κB and AP-1. Urolithin A treatment also diminished the LPS-evoked activation of NADPH oxidase (NOX), which is the main source of reactive oxygen species in activated macrophages. The inhibition of this activity by urolithin A led to the prevention of LPS-elicited NF-κB and AP-1 activation as well as Akt and JNK phosphorylation, resulting in the reduction of pro-inflammatory mediator production. Collectively, these results indicate that urolithin A treatment attenuates pro-inflammatory mediator production by suppressing NOX-derived reactive oxygen species-mediated PI3-K/Akt/NF-κB and JNK/AP-1 signaling pathways in LPS-stimulated macrophages.
Asunto(s)
Antiinflamatorios/farmacología , Cumarinas/farmacología , Inflamación/tratamiento farmacológico , NADPH Oxidasas/antagonistas & inhibidores , Transducción de Señal/efectos de los fármacos , Animales , Antiinflamatorios/uso terapéutico , Cumarinas/uso terapéutico , Inflamación/inmunología , Mediadores de Inflamación/metabolismo , Proteínas Quinasas JNK Activadas por Mitógenos/metabolismo , Lipopolisacáridos/inmunología , Masculino , Ratones , Ratones Endogámicos ICR , Modelos Animales , NADPH Oxidasas/metabolismo , FN-kappa B/metabolismo , Peritoneo/citología , Fosfatidilinositol 3-Quinasa/metabolismo , Fosforilación/efectos de los fármacos , Cultivo Primario de Células , Proteínas Proto-Oncogénicas c-akt/metabolismo , Células RAW 264.7 , Especies Reactivas de Oxígeno/inmunología , Especies Reactivas de Oxígeno/metabolismo , Transducción de Señal/inmunología , Factor de Transcripción AP-1/metabolismo , Proteínas Quinasas p38 Activadas por Mitógenos/metabolismoRESUMEN
Significant differences in findings were seen between the intake amounts of iodine-131 that were derived from direct measurements and the estimated intake from environmental monitoring data at the Fukushima accident. To clarify these discrepancies, we have investigated the iodine-131 and tellurium-132 body burdens of five human subjects, who after being exposed to a radioactive plume, underwent 21.5 h whole body counter measurements at Fukui Prefectural Hospital, so clear intake scenario and thyroid counter measurement data were available. To determine the iodine-131 and tellurium-132 body burdens, we introduced a new method of whole body counter calibration composed of a self-consistent approach with the time-dependent correction efficiency factors concept. The ratios of iodine-131 to tellurium-132, ranging from 0.96 ± 0.05 to 2.29 ± 0.38, were consistent with results of the environmental measurements. The 24 h iodine uptake values ranging from 12.1-16.0% were within euthyroid range in Japanese people. These results suggest, even if the relatively low thyroid iodine uptake in the Japanese population was taken into consideration, that there is no doubt about the consistency between direct measurements and environmental monitoring data. Adequate intake scenario is suggested to be principally important to estimate the inhaled radioactivity in areas in or around nuclear accidents.
Asunto(s)
Accidente Nuclear de Fukushima , Radioisótopos de Yodo/farmacocinética , Monitoreo de Radiación/métodos , Radioisótopos/farmacocinética , Telurio/farmacocinética , Adulto , Calibración , Femenino , Humanos , Japón , Masculino , Persona de Mediana Edad , Radiactividad , Glándula Tiroides/efectos de la radiación , Factores de Tiempo , Recuento Corporal TotalRESUMEN
Nasunin is a major anthocyanin in eggplant peel. The purpose of this study was to examine the anti-inflammatory effects of nasunin in lipopolysaccharide (LPS)-stimulated RAW264 macrophages and to identify the molecular mechanisms underlying these effects. We found that nasunin reduced the LPS-induced secretion of tumor necrosis factor-α, interleukin-6 and nitric oxide, and expression of inducible nitric oxide synthase in a dose-dependent manner. Nasunin diminished LPS-induced nuclear factor-κB (NF-κB) activation by suppressing the degradation of inhibitor of κB-α and nuclear translocation of p65 subunit of NF-κB. Nasunin also attenuated the phosphorylation of Akt and p38, signaling molecules involved in pro-inflammatory mediator production. Moreover, nasunin inhibited the intracellular accumulation of ROS, leading to the suppression of NF-κB activation, Akt and p38 phosphorylation, and subsequent pro-inflammatory mediator production. These findings suggest that nasunin exerts an anti-inflammatory effect and this effect is mediated, at least in part, by its antioxidant activity.
Asunto(s)
Antocianinas/farmacología , Mediadores de Inflamación/metabolismo , Lipopolisacáridos/farmacología , Sistema de Señalización de MAP Quinasas/efectos de los fármacos , Macrófagos/efectos de los fármacos , Especies Reactivas de Oxígeno/metabolismo , Animales , Activación Enzimática/efectos de los fármacos , Regulación Enzimológica de la Expresión Génica/efectos de los fármacos , Lipopolisacáridos/antagonistas & inhibidores , Macrófagos/citología , Macrófagos/metabolismo , Ratones , FN-kappa B/metabolismo , Óxido Nítrico/biosíntesis , Óxido Nítrico Sintasa de Tipo II/metabolismo , Fosfatidilinositol 3-Quinasas/metabolismo , Proteínas Proto-Oncogénicas c-akt/metabolismo , Células RAW 264.7 , Proteínas Quinasas p38 Activadas por Mitógenos/metabolismoRESUMEN
Normalized nucleotide and amino acid contents of complete genome sequences can be visualized as radar charts. The shapes of these charts depict the characteristics of an organism's genome. The normalized values calculated from the genome sequence theoretically exclude experimental errors. Further, because normalization is independent of both target size and kind, this procedure is applicable not only to single genes but also to whole genomes, which consist of a huge number of different genes. In this review, we discuss the applications of the normalization of the nucleotide and predicted amino acid contents of complete genomes to the investigation of genome structure and to evolutionary research from primitive organisms to Homo sapiens. Some of the results could never have been obtained from the analysis of individual nucleotide or amino acid sequences but were revealed only after the normalization of nucleotide and amino acid contents was applied to genome research. The discovery that genome structure was homogeneous was obtained only after normalization methods were applied to the nucleotide or predicted amino acid contents of genome sequences. Normalization procedures are also applicable to evolutionary research. Thus, normalization of the contents of whole genomes is a useful procedure that can help to characterize organisms.
RESUMEN
BACKGROUND: Mongolia is changing lifestyle, unhealthy habits, increase of air pollution, increasing life expectancy have led to an up rise of chronic respiratory diseases. Over 10 years ago, the prevalence of asthma and allergic rhinoconjunctivitis in Mongolia were in the lower range reported from previous studies. OBJECTIVE: The main aim of the survey is to know the prevalence of asthma and allergic rhinitis among adult population of Ulaanbaatar city, Mongolia and their risk factors. METHODS: Total of approximately 1,200 adults aged 20 years and over were planned to be randomly selected. The questionnaire was developed on the basis of WHO Protocol for Assessment of Prevalence of Major Respiratory Diseases and modified by local risk factors assessment and by other international survey approach including Global Initiative for Asthma and European Community Respiratory Health Survey. RESULTS: Prevalence of current wheezer in all age group was 15.7% (95% CI: 14.7-16.8). Age and sex segregated distribution of current wheezer were defined among male and female and prevalence was 14.5% (95% CI: 13.3-16.2) in male and female 16.6% (95% CI: 15.2-18.3) respectively. Prevalence of diagnosed asthma among adults was 4.7% (95% CI: 4.3-5.6) in all age group, 3% (95% CI: 2.4-3.7) in male and 6.8% (95% CI: 5.8-7.9) in female. Prevalence of rhinoconjunctivitis was 14.6% in all age group. 28.4% out of subjects with allergic rhinitis has current asthma, while 11.6% of subjects without allergic rhinitis has asthma (p < 0.01). CONCLUSION: The prevalence of asthma increased for one decade in Ulaanbaatar. Prevalence of diagnosed asthma is approximately 5% and current wheezer is approximately 15% in adults of population, which is close to other Asia and European countries. Allergic rhinitis is a risk factor for asthma.
RESUMEN
The anti-diabetic effect of perilla (shiso) tea was evaluated in vivo. When shiso tea was given to model rats that spontaneously developed diabetes mellitus (DM), the development of DM was decelerated. In oral glucose tolerance tests, the disappearance of blood glucose in rats administered shiso tea was reinforced. These results suggest that habitual drinking of shiso tea is effective in preventing the onset of diabetes.
Asunto(s)
Bebidas , Diabetes Mellitus/prevención & control , Conducta de Ingestión de Líquido , Perilla/química , Animales , Peso Corporal/efectos de los fármacos , Diabetes Mellitus/sangre , Diabetes Mellitus/patología , Diabetes Mellitus/fisiopatología , Islotes Pancreáticos/efectos de los fármacos , Islotes Pancreáticos/patología , Masculino , Tamaño de los Órganos/efectos de los fármacos , Ratas , Ratas Sprague-Dawley , Factores de TiempoRESUMEN
OBJECTIVE: The objective of this study is to provide basic information on the metabolic fate of five trialkyltins, namely, trimethyltin, triethyltin, tripropyltin, tributyltin, and trioctyltin, in rats. METHODS: The levels of trialkyltin and its metabolites in the liver, kidneys, brain, and blood of rats and mice were determined 24h after single oral treatment with trimethyltin, triethyltin, tripropyltin, tributyltin, and trioctyltin by gas chromatography. The doses (as tin) of the trialkyltin compounds were 2.98 mg/kg for trimethyltin and triethyltin, 18.23 mg/kg for tripropyltin and tributyltin and 24.09 mg/kg for trioctyltin. RESULTS: For the trimethyltin and triethyltin treatments, no metabolites of either trialkyltin accumulated in the organs, except for the kidney in the triethyltin treatment. The levels of trimethyltin and triethyltin in the blood of the rats were markedly higher than those of the mice. For the tripropyltin and tributyltin treatments, the predominant metabolites in the liver and kidneys were found to be dialkyltins. Furthermore, despite the higher dose, the level of total tin in the organs 24 h after treatment with trioctyltin were markedly lower than those of the other trialkyltins tested. CONCLUSION: There are clear differences in the metabolic fates of the tin metabolites of the five trialkyItins studied. These results should be considered when carrying out toxicological research on trialkyltins.
Asunto(s)
Compuestos de Trialquiltina/administración & dosificación , Compuestos de Trialquiltina/farmacocinética , Administración Oral , Animales , Cromatografía de Gases , Masculino , Ratones , Ratones Endogámicos , Ratas , Ratas Wistar , Especificidad de la Especie , Factores de Tiempo , Distribución TisularRESUMEN
The metabolic fate of tributyltin and triphenyltin may contribute to the toxicity of these chemicals. We used human hepatic cytochrome P-450 (CYP) systems to confirm the specific CYP(s) involved in the in vitro metabolism of tributyltin and triphenyltin. There were no significant sex differences in the metabolic pattern of tributyltin or triphenyltin, indicating that the CYP(s) responsible for the metabolism of these chemicals in humans is/are not sex-specific form(s). Six major drug-metabolizing isoforms of cDNA-expressed human CYPs and the CYP2C subfamily were tested to determine their metabolic capacities for tributyltin and triphenyltin. CYP2C9, 2C18, 2C19, and 3A4 significantly mediated both dealkylation and dearylation of these triorganotins. Furthermore, the metabolism of tributyltin and triphenyltin was significantly inhibited in vitro by pretreatment with selective inhibitors, azamulin for CYP3A4 and N-3-benzylnirvanol for CYP2C19. Since the CYP2C18 content of hepatic microsomes in humans is relatively low, CYP2C9, 2C19, and 3A4 might be the main isoforms of CYP that are responsible for tributyltin and triphenyltin metabolism in the human liver.
Asunto(s)
Sistema Enzimático del Citocromo P-450/metabolismo , Compuestos Orgánicos de Estaño/metabolismo , Compuestos de Trialquiltina/metabolismo , Biotransformación , Hidrocarburos Aromáticos con Puentes/farmacología , Inhibidores Enzimáticos del Citocromo P-450 , Sistema Enzimático del Citocromo P-450/biosíntesis , ADN Complementario/biosíntesis , ADN Complementario/genética , Inhibidores Enzimáticos/farmacología , Femenino , Humanos , Isoenzimas/metabolismo , Hígado/enzimología , Hígado/metabolismo , Masculino , Mefenitoína/análogos & derivados , Mefenitoína/farmacología , Microsomas Hepáticos/enzimología , Proteínas Recombinantes/metabolismo , Triazoles/farmacologíaRESUMEN
Tributyltin is metabolized by cytochrome P-450 (CYP) system enzymes, and its metabolic fate may contribute to the toxicity of the chemical. In the present study, it is examined whether sex differences in the metabolism of tributyltin exist in rats. In addition, the in vivo and in vitro metabolism of tributyltin was investigated using rat hepatic CYP systems to confirm the principal CYP involved. A significant sex difference in metabolism occurred both in vivo and in vitro, suggesting that one of the CYPs responsible for tributyltin metabolism in rats is male specific or predominant at least. Eight cDNA-expressed rat CYPs, including typical phenobarbital (PB)-inducible forms and members of the CYP2C subfamily, were tested to determine their capability for tributyltin metabolism. Among the enzymes studied, a statistically significant dealkylation of tributyltin was mediated by CYP2C6 and 2C11. Furthermore, the sex difference in metabolism disappeared in vitro after anti-rat CYP2C11 antibody pretreatment because CYP2C11 is a major male-specific form in rats. These results indicate that CYP2C6 is the principal CYP for tributyltin metabolism in female rats, whereas CYP2C11 as well as 2C6 is involved in tributyltin metabolism in male rats, and it is suggested that CYP2C11 is responsible for the significant sex difference in the metabolism of tributyltin observed in rats.
Asunto(s)
Hidrocarburo de Aril Hidroxilasas/metabolismo , Sistema Enzimático del Citocromo P-450/metabolismo , Microsomas Hepáticos/enzimología , Esteroide 16-alfa-Hidroxilasa/metabolismo , Esteroide 21-Hidroxilasa/metabolismo , Compuestos de Trialquiltina/farmacocinética , Animales , Hidrocarburo de Aril Hidroxilasas/biosíntesis , Sistema Enzimático del Citocromo P-450/biosíntesis , Familia 2 del Citocromo P450 , ADN Complementario/biosíntesis , Femenino , Inactivación Metabólica , Masculino , Ratas , Ratas Wistar , Caracteres Sexuales , Esteroide 16-alfa-Hidroxilasa/biosíntesis , Esteroide 21-Hidroxilasa/biosíntesisRESUMEN
The in vivo and in vitro metabolism of triphenyltin using rat hepatic cytochrome P-450 (CYP) systems was investigated to confirm the specific CYP that is closely related to triphenyltin metabolism. No significant sex differences occurred between the in vivo and in vitro metabolic patterns of the chemical, indicating that the principal CYP for triphenyltin metabolism in rats is not a sex-specific form of CYP. In addition, seven types of complementary DNA (cDNA)-expressed rat CYPs, typical phenobarbital (PB)-inducible forms and the CYP2C subfamily were tested to determine the activity of triphenyltin metabolism. Among the CYP isoforms studied, although CYP2B1 had a small metabolic capacity, a marked dearylation of the chemical was induced by CYP2C6. Furthermore, anti-rat CYP2C6 antibodies and cimetidine, a selective CYP2C6 inhibitor, inhibited triphenyltin dearylation activity in the hepatic microsomes of rats. Taken together, these findings suggest that CYP2C6 is the principal CYP for the triphenyltin metabolism in rats.
Asunto(s)
Antiinfecciosos/metabolismo , Antiinfecciosos/toxicidad , Sistema Enzimático del Citocromo P-450/biosíntesis , Sistema Enzimático del Citocromo P-450/farmacología , Compuestos Orgánicos de Estaño/metabolismo , Compuestos Orgánicos de Estaño/toxicidad , Esteroide 21-Hidroxilasa/biosíntesis , Esteroide 21-Hidroxilasa/farmacología , Animales , Familia 2 del Citocromo P450 , Femenino , Hígado , Masculino , Microsomas Hepáticos/enzimología , Ratas , Ratas WistarRESUMEN
Tributyltin and triphenyltin are metabolized by cytochrome P-450 system enzymes, and their metabolic fate may contribute to the toxicity of the chemicals. In the current study, the in vitro metabolism of tributyltin and triphenyltin by rat, hamster and human hepatic microsomes was investigated to elucidate the metabolic competence for these compounds in humans. The metabolic reaction using microsome-NADPH system that is usually conducted was not applicable to in vitro metabolism of organotins, especially triphenyltin. We therefore examined the effects of dithiothreitol (DTT), one of the antioxidants for sulfhydryl groups, to determine the in vitro metabolism of tributyltin and triphenyltin. As a result, the treatment with 0.1 mM DTT in vitro increased the activity of the microsomal monooxygenase system for metabolism of tributyltin as well as triphenyltin; the total yield of tributyltin and triphenyltin metabolites as tin increased, respectively, by approximately 1.8 and 8.9 times for rat, 2.1 and 1.2 times for hamster, and 1.6 and 1.5 times for human. It is suggested that the organotins directly inactivate cytochrome P-450 because of the interaction with critical sulfhydryl groups of the hemoprotein. We confirmed the utility of this in vitro metabolic system using DTT in the hepatic microsomes of phenobarbital (PB)-pretreated and untreated hamsters. Thus, the in vitro metabolic system described here was applied to a comparative study of the metabolism of organotins in rats, hamsters and humans. Tributyltin was metabolized more readily than triphenyltin in all the species. In humans, the in vitro metabolic pattern resembled that of hamsters, which were susceptible to in vivo triphenyltin toxicity because of incompetent metabolism. It is possible that the hamster is a qualitatively and quantitatively suitable animal model for exploring the influence of tributyltin and triphenyltin in humans.
Asunto(s)
Microsomas Hepáticos/metabolismo , Compuestos Orgánicos de Estaño/metabolismo , Compuestos de Trialquiltina/metabolismo , Adulto , Anciano , Animales , Cricetinae , Sistema Enzimático del Citocromo P-450/metabolismo , Femenino , Humanos , Técnicas In Vitro , Masculino , Persona de Mediana Edad , Compuestos Orgánicos de Estaño/toxicidad , Ratas , Ratas Wistar , Especificidad de la Especie , Compuestos de Trialquiltina/toxicidadRESUMEN
The metabolism of tetraphenyltin in rat liver and kidney has been examined. Tetraphenyltin and its metabolites in the tissue were determined periodically for 96 h after a single oral dose of 55.4 mg kg(-1) of tetraphenyltin by gas chromatography. The gas chromatographic method was able to determine simultaneously both inorganic tin and phenyltin compounds. Although initial (at 24 h) levels of tetraphenyltin in the liver approximated four times those in the kidneys, the levels of tetraphenyltin decreased more rapidly with time than those in the kidneys. These findings show that the tetraphenyltin accumulated more rapidly and highly in the liver, but was metabolized faster than that in the kidney. The levels of total tin in the liver 24 h after treatment were distinctly lower than those of di- or triphenyltin treatments in our previous studies and none of the animals showed characteristic symptoms. The toxic potencies of organotins generally correlate with accumulation of the chemicals. These results imply that the slight toxicities of tetraphenyltin might be due to the relatively low uptake of tin compounds after ingestion. The highest tin concentration among the metabolites of tetraphenyltin in the tissue, especially in liver, was observed as diphenyltin throughout the time period studied. These results suggest that part of the administered tetraphenyltin may cause some harmful effects as diphenyltin in rats, and this must be taken into consideration in toxicological research on tetraphenyltin.