RESUMEN
The obesogen hypothesis states that together with an energy imbalance between calories consumed and calories expended, exposure to environmental compounds early in life or throughout lifetime might have an influence on obesity development. In this work, we propose a new approach for obesogen screening, i.e., the use of transcriptomics in the 3T3-L1 pre-adipocyte cell line. Based on the data from a previous study of our group using a lipid accumulation based adipocyte differentiation assay, several human-relevant obesogenic compounds were selected: reference obesogens (Rosiglitazone, Tributyltin), test obesogens (Butylbenzyl phthalate, butylparaben, propylparaben, Bisphenol A), and non-obesogens (Ethylene Brassylate, Bis (2-ethylhexyl)phthalate). The high stability and reproducibility of the 3T3-L1 gene transcription patterns over different experiments and cell batches is demonstrated by this study. Obesogens and non-obesogen gene transcription profiles were clearly distinguished using hierarchical clustering. Furthermore, a gradual distinction corresponding to differences in induction of lipid accumulation could be made between test and reference obesogens based on transcription patterns, indicating the potential use of this strategy for classification of obesogens. Marker genes that are able to distinguish between non, test, and reference obesogens were identified. Well-known genes involved in adipocyte differentiation as well as genes with unknown functions were selected, implying a potential adipocyte-related function of the latter. Cell-physiological lipid accumulation was well estimated based on transcription levels of the marker genes, indicating the biological relevance of omics data. In conclusion, this study shows the high relevance and reproducibility of this 3T3-L1 based in vitro toxicogenomics tool for classification of obesogens and biomarker discovery. Although the results presented here are promising, further confirmation of the predictive value of the set of candidate biomarkers identified as well as the validation of their clinical role will be needed.
Asunto(s)
Obesidad/inducido químicamente , Toxicogenética , Células 3T3-L1 , Adipocitos/citología , Adipocitos/efectos de los fármacos , Animales , Diferenciación Celular , Humanos , Ratones , Análisis de Secuencia por Matrices de Oligonucleótidos , Reproducibilidad de los Resultados , Transcripción GenéticaRESUMEN
INTRODUCTION: Persistent Organic Pollutants (POPs) accumulate in adipose tissue and some are described to possess endocrine disrupting capacities. Therefore, it is important to evaluate their effects on key endocrine pathways in adipose tissue (AT), to further evaluate their potential role in metabolic pathologies such as obesity. OBJECTIVES: THE AIM IS TWOFOLD: (i) evaluate gene expression levels of obesity marker genes, i.e. the adipokines leptin (LEP), adiponectin (ADIPOQ) and Tumor Necrosis Factor α (TNFα) and the nuclear receptor, Peroxisome Proliferator Activated Receptor γ (PPARγ) in paired subcutaneous (SAT) and visceral (VAT) AT of obese subjects (n = 50) and to relate these values to serum concentrations of LEP and ADIPOQ (ii) evaluate the association of expression levels of marker genes in AT and serum with POP concentrations in AT. RESULTS AND CONCLUSIONS: Leptin and adiponectin levels in serum were positively correlated to respectively expression levels of leptin in SAT and adiponectin in VAT. Our study shows more significant correlations between gene expression of obesity marker genes and POP concentrations in VAT compared to SAT. Since VAT is more important than SAT in pathologies associated with obesity, this suggests that POPs are able to influence the association between obesity and the development of associated pathologies. Moreover, this finding reveals the importance of VAT when investigating the obesogen hypothesis. Concerning PPARγ expression in VAT, negative correlations with polychlorinated biphenyls (PCBs) concentrations were found in non T2D patients. LEP serum concentrations correlated with several PCBs in women whereas in men no correlations were found. This strengthens the potential importance of gender differences in obesity and within the obesogen hypothesis.
Asunto(s)
Tejido Adiposo/metabolismo , Expresión Génica , Obesidad/genética , Obesidad/metabolismo , Adolescente , Adulto , Biomarcadores/sangre , Biomarcadores/metabolismo , Femenino , Humanos , Grasa Intraabdominal/metabolismo , Masculino , Persona de Mediana Edad , Grasa Subcutánea/metabolismo , Adulto JovenRESUMEN
Recently the environmental obesogen hypothesis has been formulated, proposing a role for endocrine disrupting compounds (EDCs) in the development of obesity. To evaluate this hypothesis, a screening system for obesogenic compounds is urgently needed. In this study, we suggest a standardised protocol for obesogen screening based on the 3T3-L1 cell line, a well-characterised adipogenesis model, and direct fluorescent measurement using Nile red lipid staining technique. In a first phase, we characterised the assay using the acknowledged obesogens rosiglitazone and tributyltin. Based on the obtained dose-response curves for these model compounds, a lipid accumulation threshold value was calculated to ensure the biological relevance and reliability of statistically significant effects. This threshold based method was combined with the well described strictly standardized mean difference (SSMD) method for classification of non-, weak- or strong obesogenic compounds. In the next step, a range of EDCs, used in personal and household care products (parabens, musks, phthalates and alkylphenol compounds), were tested to further evaluate the obesogenicity screening assay for its discriminative power and sensitivity. Additionally, the peroxisome proliferator activated receptor γ (PPARγ) dependency of the positive compounds was evaluated using PPARγ activation and antagonist experiments. Our results showed the adipogenic potential of all tested parabens, several musks and phthalate compounds and bisphenol A (BPA). PPARγ activation was associated with adipogenesis for parabens, phthalates and BPA, however not required for obesogenic effects induced by Tonalide, indicating the role of other obesogenic mechanisms for this compound.
Asunto(s)
Disruptores Endocrinos/efectos adversos , Disruptores Endocrinos/análisis , Obesidad/inducido químicamente , PPAR gamma/metabolismo , Células 3T3-L1 , Adipocitos/efectos de los fármacos , Adipocitos/metabolismo , Adipocitos/patología , Animales , Diferenciación Celular/efectos de los fármacos , Insulina/farmacología , Ratones , Obesidad/genética , PPAR gamma/antagonistas & inhibidores , PPAR gamma/genética , Estándares de Referencia , Coloración y Etiquetado , Activación Transcripcional/efectos de los fármacos , Activación Transcripcional/genéticaRESUMEN
BACKGROUND: The metabolic disruptor hypothesis postulates that environmental pollutants may be risk factors for metabolic diseases. Because insulin resistance is involved in most metabolic diseases and current health care prevention programs predominantly target insulin resistance or risk factors thereof, a critical analysis of the role of pollutants in insulin resistance might be important for future management of metabolic diseases. OBJECTIVES: We aimed to critically review the available information linking pollutant exposure to insulin resistance and to open the discussion on future perspectives for metabolic disruptor identification and prioritization strategies. METHODS: We searched PubMed and Web of Science for experimental studies reporting on linkages between environmental pollutants and insulin resistance and identified a total of 23 studies as the prime literature. DISCUSSION: Recent studies specifically designed to investigate the effect of pollutants on insulin sensitivity show a potential causation of insulin resistance. Based on these studies, a summary of viable test systems and end points can be composed, allowing insight into what is missing and what is needed to create a standardized insulin resistance toxicity testing strategy. CONCLUSIONS: It is clear that current research predominantly relies on top-down identification of insulin resistance-inducing metabolic disruptors and that the development of dedicated in vitro or ex vivo screens to allow animal sparing and time- and cost-effective bottom-up screening is a major future research need.
Asunto(s)
Exposición a Riesgos Ambientales/estadística & datos numéricos , Contaminantes Ambientales/toxicidad , Resistencia a la Insulina/fisiología , Enfermedades Metabólicas/inducido químicamente , Enfermedades Metabólicas/epidemiología , Enfermedades Metabólicas/fisiopatología , Pruebas de Toxicidad/métodos , Humanos , PubMed , Proyectos de Investigación/tendencias , Factores de RiesgoRESUMEN
Environmental pollutants have recently emerged as potential risk factors for metabolic diseases, urging systematic investigation of pollutant effects on metabolic disease processes. To enable risk assessment of these so-called metabolic disruptors the use of stable, robust and well-defined cell based screening systems has recently been encouraged. Since beta-cell (dys)functionality is central in diabetes pathophysiology, the need to develop beta-cell based pollutant screening systems is evident. In this context, the present research evaluated the strengths and weaknesses of the INS-1 832/13 pancreatic beta-cell line as diabetogenic pollutant screening system with a focus on beta-cell function. After optimization of exposure conditions, positive (exendin-4, glibenclamide) and negative (diazoxide) control compounds for acute insulin secretion responses were tested and those with the most profound effects were selected to allow potency estimations and ranking of pollutants. This was followed by a first explorative screening of acute bisphenol A and bis(2-ethylhexyl)phthalate effects. The same approach was applied for chronic exposures, focusing primarily on evaluation of acknowledged chronic stimulators (diazoxide, T0901317, exendin-4) or inhibitors (glibenclamide) of insulin secretion responses to select the most responsive ones for use as control compounds in a chronic pollutant testing framework. Our results showed that INS-1 832/13 cells responded conform previous observations regarding acute effects of control compounds on insulin secretion, while bisphenol A and bis(2-ethylhexyl)phthalate had limited acute effects. Furthermore, chronic exposure to known beta-cell reactive compounds resulted in deviating insulin secretion and insulin content profiles compared to previous reports. In conclusion, this INS-1 subclone appears to lack certain characteristics needed to respond appropriately to acute pollutant exposure or long term exposure to known beta-cell reactive compounds and thus seems to be, in our setting, inadequate as a diabetogenic pollutant screening system.
Asunto(s)
Células Secretoras de Insulina/efectos de los fármacos , Células Secretoras de Insulina/metabolismo , Compuestos de Bencidrilo/toxicidad , Línea Celular , Diazóxido/toxicidad , Exenatida , Gliburida/toxicidad , Humanos , Hidrocarburos Fluorados/toxicidad , Insulina/metabolismo , Secreción de Insulina , Péptidos/toxicidad , Fenoles/toxicidad , Ácidos Ftálicos/toxicidad , Sulfonamidas/toxicidad , Ponzoñas/toxicidadRESUMEN
Obesogenic compounds are chemicals that have an influence on obesity development. This study was designed to unravel the molecular mechanisms of the model obesogen TBT, using microarray analysis in the 3T3-L1 in vitro system, and to evaluate the use of toxicogenomics for obesogen screening. The microarray results revealed enrichment of Gene Ontology terms involved in energy and fat metabolism after 10 days of TBT exposure. Pathway analysis unveiled PPAR signalling pathway as the sole pathway significantly enriched after 1 day and the most significantly enriched pathway after 10 days of exposure. To our knowledge, this is the first study delivering an in depth mechanistic outline of the mode of action of TBT as an obesogen, combining effects on both cell physiological and gene expression level. Furthermore, our results show that combining transcriptomics with 3T3-L1 cells is a promising tool for screening of potential obesogenic compounds.
Asunto(s)
Metabolismo Energético/efectos de los fármacos , Metabolismo de los Lípidos/efectos de los fármacos , Obesidad/inducido químicamente , Compuestos de Trialquiltina/farmacología , Células 3T3 , Adipocitos/efectos de los fármacos , Adipocitos/metabolismo , Adipoquinas/genética , Animales , Línea Celular , Colesterol/metabolismo , Estrógenos/metabolismo , Expresión Génica , Glucocorticoides/genética , Glucocorticoides/metabolismo , Ratones , Receptores Activados del Proliferador del Peroxisoma/metabolismo , Transducción de Señal , Triglicéridos/metabolismo , Proteínas Wnt/metabolismo , Vía de Señalización WntRESUMEN
This study was designed to evaluate if the rat H4IIE hepatoma cell line is a physiologically relevant model to study hepatic insulin responses to hint at its prospective application in pollutant-related insulin resistance research. DNA microarray analysis, real-time PCR and flow cytometric cell cycle analysis were used to assess the relevance of the insulin response in H4IIE cells. Insulin dose dependently stimulated H4IIE growth and time dependently altered the expression of the known insulin responsive genes: Fasn, Pck1 and Irs2. Microarray analysis performed on cells exposed to insulin (100nM) for 6h and 24h showed that genes related to carbohydrate and lipid metabolism were most profoundly afflicted, in accordance with in vivo hepatic insulin action. Since changes in carbohydrate and lipid metabolism are pivotal in the pathogenesis of insulin resistance, the presence of a physiological relevant insulin response in H4IIE cells pleads for further testing of its potential use in research on pollutant-driven insulin resistance.
Asunto(s)
Carcinoma Hepatocelular/metabolismo , Resistencia a la Insulina , Neoplasias Hepáticas/metabolismo , Animales , Metabolismo de los Hidratos de Carbono/efectos de los fármacos , Ciclo Celular , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Citometría de Flujo , Metabolismo de los Lípidos/efectos de los fármacos , Hígado/metabolismo , Análisis de Secuencia por Matrices de Oligonucleótidos , Ratas , Reacción en Cadena en Tiempo Real de la Polimerasa , Transducción de Señal/efectos de los fármacosRESUMEN
The need for implementation of effects on steroid synthesis and hormone processing in screening batteries of endocrine disruptive compounds is widely acknowledged. In this perspective, hormone profiling in the H295R adrenocortical cell system is extensively examined and recently OECD validated (TG 456) as a replacement of the minced testis assay. To further elucidate the complete mechanisms and endocrine responsiveness of this cell system, microarray-based gene expression profiling of the cAMP response pathway, one of the major pathways in steroidogenesis regulation, was examined in H295R cells. Next to the steroid synthesis pathway, a broader lipid metabolic pathway, including cholesterol uptake/biosynthesis, hormone metabolization and many hormone and nuclear receptors, are sensitive towards cAMP stimulation in this cell system. Moreover, these pathways were clearly dose and time responsive, indicating early regulation (10 h) of cholesterol uptake and mobilization genes and later expression (24-48 h) of cholesterol biosynthesis and steroid synthesis. Transcription network analysis suggested several important transcription factors that could be involved in regulation of the steroid hormone pathway, of which HNF4α, a broader lipid metabolism related transcription factor, might indicate some new transcription regulation patterns in this cell line. Overall we can conclude that the time dependent gene expression patterns of the strongly coordinated cholesterol supply and steroidogenesis pathways in the H295R cell system seem to reflect well the in vivo ACTH/cAMP signalling cascade in adrenal cells. Moreover, the completeness of the steroidogenic related pathways in terms of gene expression sensitivity, indicates the H295R cell line as a promising cell line in omics-based endocrine disruption screening.
Asunto(s)
Corticoesteroides/biosíntesis , Corteza Suprarrenal/efectos de los fármacos , Pruebas de Toxicidad/métodos , Corteza Suprarrenal/citología , Corteza Suprarrenal/metabolismo , Hormona Adrenocorticotrópica/biosíntesis , Vías Biosintéticas/efectos de los fármacos , Línea Celular , Colesterol/biosíntesis , AMP Cíclico/metabolismo , Humanos , Análisis de Secuencia por Matrices de Oligonucleótidos/métodos , Pruebas de Toxicidad/normasRESUMEN
In vitro estrogenicity screens are believed to provide a first prioritization step in hazard characterization of endocrine disrupting chemicals. When applied to complex environmental matrices or mixture samples, they have been indicated valuable in estimating the overall estrogen-mimicking load. In this study, the performance of an adapted format of the classical E-screen or MCF-7 cell proliferation assay was profoundly evaluated to rank pure compounds as well as influents and effluents of sewage treatment plants (STPs) according to estrogenic activity. In this adapted format, flow cytometric cell cycle analysis was used to allow evaluation of the MCF-7 cell proliferative effects after only 24 h of exposure. With an average EC(50) value of 2 pM and CV of 22%, this assay appears as a sensitive and reproducible system for evaluation of estrogenic activity. Moreover, estrogenic responses of 17 pure compounds corresponded well, qualitatively and quantitatively, with other in vitro and in vivo estrogenicity screens, such as the classical E-screen (R(2)=0.98), the estrogen receptor (ER) binding (R(2)=0.84) and the ER transcription activation assay (R(2)=0.87). To evaluate the applicability of this assay for complex samples, influents and effluents of 10 STPs covering different treatment processes, were compared and ranked according to estrogenic removal efficiencies. Activated sludge treatment with phosphorus and nitrogen removal appeared most effective in eliminating estrogenic activity, followed by activated sludge, lagoon and filter bed. This is well in agreement with previous findings based on chemical analysis or biological activity screens. Moreover, ER blocking experiments indicated that cell proliferative responses were mainly ER mediated, illustrating that the complexity of the end point, cell proliferation, compared to other ER screens, does not hamper the interpretation of the results. Therefore, this study, among other E-screen studies, supports the use of MCF-7 cell proliferation as estrogenicity screen for pure compounds and complex samples.
Asunto(s)
Disruptores Endocrinos/toxicidad , Estrógenos/toxicidad , Citometría de Flujo , Contaminantes Químicos del Agua/toxicidad , Bioensayo , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Disruptores Endocrinos/química , Monitoreo del Ambiente , Estrógenos/química , Humanos , Receptores de Estrógenos/metabolismo , Aguas del Alcantarillado/química , Eliminación de Residuos Líquidos , Contaminantes Químicos del Agua/químicaRESUMEN
Trichlorfon (TRC) is the most common organophosphorous insecticide used in aquaculture practices in Southeast Asian countries. Indiscriminate use of TRC can either damage or alter the enzymatic and hormonal activities in the living organisms. In this present study, therefore, toxicogenomic analyses using real time PCR was used to characterize expression levels of various genes in Pangasianodon hypophthalmus after exposure to three concentrations, the 96 h 1/100LC(50) (0.01 mg/L), the 96 h 110LC(50) (0.1 mg/L) and the 96 h 12LC(50) (0.5 mg/L) of TRC for 6 h, 24 h, 96 h, 7 days, 14 days, 28 days and 56 days respectively. The expression kinetics of stress and other cellular toxicity representative genes such as heat shock protein70 (HSP70), growth hormone, acetylcholinesterase (AChE), trypsinogen, cytochrome P4501B (CYP1B) and cytochrome oxidase subunit 1 (COI) were investigated in liver and gills. TRC at a level of 0.1 mg/L and 0.5 mg/L induced a time and dose-dependent increase in the expression of the HSP70, COI and CYPIB while the transcript level of AChE, growth hormone and trypsinogen were significantly down-regulated. These results could permit to develop a "molecular biomarker system" which can be applied as a first-tier method of identifying contaminant exposure before effects at population level occur.
Asunto(s)
Bagres/metabolismo , Proteínas de Peces/metabolismo , Expresión Génica/efectos de los fármacos , Insecticidas/toxicidad , Triclorfón/toxicidad , Animales , Biomarcadores/metabolismo , Bagres/genética , Bagres/crecimiento & desarrollo , Exposición a Riesgos Ambientales , Proteínas de Peces/genética , HumanosRESUMEN
Gene delivery has become an increasingly important strategy for treating a variety of human diseases, including infections, genetic disorders and tumours. To avoid the difficulties of using viral carriers, more and more non-viral gene delivery nanoparticles are developed. Among these new approaches polyethylene imine (PEI) is currently considered as one of the most effective polymer based method solution and considered as the gold standard. The toxicity of nanoparticles is a major concern when used for medical application. In this study we chose two nanoparticles for an in depth toxicological and ecotoxicological evaluation, one well characterized, PEI, and another novel polymer, poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA). In the present study we have assessed the toxicity of these cation nanoparticles as such and of the polyplexes - nanoparticles covered with DNA. As these nanoparticles are also frequently used in high volumes in various industries and as such may enter in the environment, we also made an initial assessment of ecotoxicological effects assessment. The following nanoparticles related aspects have been studied during the project: development and characterization, ecotoxicity, general toxicity and specific toxicity. To this end a battery of different tests was used. The conclusion of these tests is that toxicity is varying between different nanoparticles and between different DNA covering ratios. In general, in the different systems tested, the PEI polymer is more toxic than the PDMAEMA polymer. The same difference is seen for the polyplexes and the higher the charge ratio, the more toxic are the polyplexes. Our study also clearly shows the need for a broad spectrum of toxicity assays for a comprehensive risk assessment. Our study has performed such a comprehensive analysis of two biomedical nanoparticles.
Asunto(s)
Contaminantes Ambientales/toxicidad , Nanopartículas/toxicidad , Polietileneimina/toxicidad , Ácidos Polimetacrílicos/toxicidad , Anomalías Inducidas por Medicamentos/embriología , Animales , Refuerzo Biomédico , Línea Celular , Citocinas/metabolismo , Escherichia coli/efectos de los fármacos , Escherichia coli/genética , Eucariontes/efectos de los fármacos , Expresión Génica/efectos de los fármacos , Perfilación de la Expresión Génica , Técnicas de Transferencia de Gen , Hepatocitos/efectos de los fármacos , Humanos , Nanopartículas/química , Polietileneimina/química , Ácidos Polimetacrílicos/química , Piel/efectos de los fármacos , Pruebas de Toxicidad/métodos , XenopusRESUMEN
To study the reliability between in vitro and in vivo data collected downstream 2 sewage treatment plants (STP) as well as from bleached kraft mill industry (BKME), 5 rivers (3 impacted and 2 references) were investigated in the Walloon region (southern of Belgium). For the in vitro part of the work, water samples were collected to measure the estrogenicity of the 'out' effluent compared to reference sample point by MCF-7 assay. Results indicated significant estrogenicity of effluents from STP and BKME and a weak estrogenicity in reference sites. However, estradiol equivalents (EEQ) estimated into rivers were probably too low to impact wild population. Chemical analysis of 13 compounds of interest indicated that extraction procedure used in this study gave low recoveries of estrogen-like xenobiotics, leading to probably under-estimated MCF-7 responses. Surprisingly, a full scan mode has revealed an unexpected compound in the sample of BKME which was: 7-isopropyl-1,1,4a-trimethyl-1,2,3,4a,9,10,10a-octahydrophenanthrene, a product of pulp mill manufacture. In parallel to in vitro, in vivo assessment of estrogenic impact of effluent was followed on the gudgeon (Gobio gobio). Samples were achieved during 2 different periods of the reproductive cycle, resting period (RP) and pre-spawning period (pSP). Unspecific physiological parameters to estrogenic exposure (gonadosomatic index and systematic testis cell counting) displayed no significant differences related to endocrine disruption of the reproductive tract, only differences were correlated with the reproductive state of fish (RP versus pSP). Concerning the potent biomarker of estrogen exposure, vitellogenin (vtg), only basal induction was revealed but not related to estrogenic exposure. Nevertheless, vtg over-expression was found for male fish presenting a feminization of the reproductive tract captured downstream the STP station of Wégnez in the Vesdre River. Intersexuality, another indicator of the estrogenicity impact in fish, was observed in every site. Actually, ovotestis was systematically formed by protoplasmic oocyte observed in low percentage in every group analysed (impacted and references). Moreover, in fish captured in Wégnez, oocyte diameter was significantly higher compared to the other groups. In this study, only moderate to none impact in population of gudgeon was noticed. Moreover, in this case no discrepancy between in vitro and vivo was viewed although both approaches revealed gaps in monitoring effluent incidence into the environment. We should remain careful in the interpretation when only partial approaches are used in order to characterize impact in the aquatic milieu.
Asunto(s)
Ecosistema , Disruptores Endocrinos/efectos adversos , Estrógenos no Esteroides/efectos adversos , Residuos Industriales/efectos adversos , Contaminantes Químicos del Agua/efectos adversos , Animales , Animales Salvajes , Bélgica , Línea Celular Tumoral , Trastornos del Desarrollo Sexual/inducido químicamente , Trastornos del Desarrollo Sexual/patología , Disruptores Endocrinos/análisis , Exposición a Riesgos Ambientales/efectos adversos , Exposición a Riesgos Ambientales/análisis , Monitoreo del Ambiente/métodos , Estrógenos no Esteroides/análisis , Femenino , Peces/fisiología , Gónadas/efectos de los fármacos , Gónadas/crecimiento & desarrollo , Gónadas/patología , Humanos , Residuos Industriales/análisis , Papel , Reproducibilidad de los Resultados , Ríos , Aguas del Alcantarillado , Eliminación de Residuos Líquidos , Contaminantes Químicos del Agua/análisisRESUMEN
Biomonitoring allows an integrated evaluation of different aspects of exposure, accumulation and effects to environmental pollution, simultaneously accounting for the natural variety between individuals in an ecosystem. In this study, the effects of increased metal accumulation were evaluated at the biochemical level in terms of two biomarker responses in the great tit (Parus major), a small insectivorous songbird, along an established metal pollution gradient. Metal concentrations in internal tissues (liver and kidney) and blood indicated that lead and cadmium were the most important metals in the pollution gradient under study. At the biochemical level, induction of metal binding protein metallothionein (MT) in liver and kidney reflected cadmium concentrations in these tissues (R(2)=0.42 and R(2)=0.94 respectively, n=19), although in kidney, MT induction was not sufficient to complex all cadmium present. Secondly, the activity of the enzyme delta-aminolevulinic acid dehydratase (ALAd) in blood decreased exponentially in response to increased lead accumulation (R(2)=0.70, n=18) and represents therefore a specific effect marker for lead exposure. In the highest polluted area, an ALAd inhibition of 85% was reported. Since a higher metal exposure resulted in an increased metal accumulation and subsequent biomarker responses in a dose-dependent way, this study indicates the applicability of ALAd and MT levels in great tits for biomonitoring responses to heavy metal pollution.
Asunto(s)
Aves , Contaminantes Ambientales/farmacocinética , Riñón/efectos de los fármacos , Hígado/efectos de los fármacos , Metalotioneína/farmacología , Metales Pesados/farmacocinética , Porfobilinógeno Sintasa/farmacocinética , Animales , Biomarcadores/análisis , Cadmio/sangre , Cadmio/farmacocinética , Relación Dosis-Respuesta a Droga , Monitoreo del Ambiente , Contaminantes Ambientales/sangre , Geografía , Riñón/metabolismo , Plomo/sangre , Plomo/farmacocinética , Hígado/metabolismo , Metalotioneína/sangre , Metales Pesados/sangre , Porfobilinógeno Sintasa/antagonistas & inhibidores , Porfobilinógeno Sintasa/sangre , Distribución Tisular , Zinc/sangre , Zinc/farmacocinéticaRESUMEN
We investigated estrogen-like properties of five perfluorinated compounds using a combination of three in vitro assays. By means of an E-screen assay, we detected the proliferation-promoting capacity of the fluorotelomer alcohols 1H,1H,2H,2H-perfluorooctan-1-ol (6:2 FTOH) and 1H,1H,2H,2H-perfluoro-decan-1-ol (8:2 FTOH). The more widely environmentally distributed compounds perfluoro-1-octane sulfonate, perfluorooctanoic acid, and perfluorononanoic acid did not seem to possess this hormone-dependent proliferation capacity. We investigated cell cycle dynamics using flow cytometric analyses of the DNA content of the nuclei of MCF-7 breast cancer cells. Exposure to both fluorotelomer alcohols stimulated resting MCF-7 cells to reenter the synthesis phase (S-phase) of the cell cycle. After only 24 hr of treatment, we observed significant increases in the percentage of cells in the S-phase. In order to further investigate the resemblance of the newly detected xenoestrogens to the reference compound 17beta-estradiol (E2), gene expression of a number of estrogen-responsive genes was analyzed by real-time polymerase chain reaction. With E2, as well as 4-nonylphenol and the fluorotelomer alcohols, we observed up-regulation of trefoil factor 1, progesterone receptor, and PDZK1 and down-regulation of ERBB2 gene expression. We observed small but relevant up-regulation of the estrogen receptor as a consequence of exposures to 6:2 FTOH or 8:2 FTOH. The latter finding suggests an alternative mode of action of the fluorotelomer alcohols compared with that of E2. This study clearly underlines the need for future in vivo testing for specific endocrine-related end points.