AVALTOX

Eina informàtica per l'autoaprenentage i autoavaluació sobre Metodologia d'Avaluació Experimental de la ToxicitatGrup d'Innovació Docent ORFIL

Developmental neurotoxicity of MDMA. A systematic literature review summarized in a putative adverse outcome pathway

The increasing use of illegal drugs by pregnant women causes a public health concern because it is associated with health risks for mothers and their developing children. One of such drugs is MDMA (3,4-methylenedioxymethamphetamine) or ecstasy due to its high consumption in relevant age and sex groups and its adverse effects on human and rodent developing brains. To Journal Pre-proof 2 thoroughly review the current knowledge on the developmentally neurotoxic potential of MDMA we systematically collected and summarized articles investigating developmental neurotoxicity (DNT) of MDMA in humans and animals in in vivo and in vitro. In addition, we summarized the findings in a putative adverse outcome pathway (AOP). From an initial 299 articles retrieved from the bibliographic databases Web of Science, PubMed and DART, we selected 39 articles according to inclusion/exclusion criteria for data collection after title/abstract and full text screening. Of these 3 where epidemiological studies, 34 where in vivo studies in mice and rats and 2 were in vitro studies. The three epidemiological studies reported from the same longitudinal study and suggested that MDMA exposure during pregnancy impairs neuromotor function in infants. In rat, postnatal exposure towards MDMA also caused locomotor deficits as well as impaired spatial learning that might be associated with decreased serotonin levels in the hippocampus. In vitro MDMA caused cytotoxicity at high concentrations and effects on the serotonergic and neuritogenic alterations at lower concentrations which are in line with some of the in vivo alterations observed. Considering the adverse outcomes of developmental MDMA described in humans and in rodents we summarized the first putative AOP on developmental compound exposure leading to impaired neuromotor function in children. For generation of this AOP, MDMA exposure was taken as a model compound. In addition, we hypothesized a second AOP involving developmental disturbance of the dopaminergic system. However, further in vitro mechanistic studies are needed to understand the molecular initiating event(s) (MIE) triggering the downstream cascades and obtain consistent evidences causally linking the adverse outcome to effects at the cellular, organ and organism level

Implementation of a functional endpoint to the zebrafish embryotoxicity test to evaluate craniofacial abnormalities

The inclusion of a read-out to detect functional consequences of craniofacial alterations in the zebrafish embryotoxicity test will allow to evaluate these alterations which are difficult to assess morphologically, and to detect alterations in cranial nerves functions leading to impairment of jaw movements. In this study we have established an ingestion test in zebrafish larvae younger than 120 hpf. To overcome the challenge of evaluating larvae which still do not present independent feeding behaviour, we have tested the ability of 72, 96 or 102 hpf larvae to ingest food mixed with fluorescent microspheres under several conditions (dark/light, with/without shaking) to find the best experimental set-up for the test. We have included the investigation of two substances as potential positive controls: ketoconazole and tricaine. Ketoconazole 10 μM exposure during development produced significant embryotoxic effects including a characteristic craniofacial alteration pattern consisting in impaired development of brain, nasal cavity, mouth opening and jaw, as well as a significant decrease in food intake. Tricaine exposure at 380 μM during the food availability period significantly decreased the food intake. The method proposed will be a useful alternative tool to animal testing to detect compounds inducing adverse effects on craniofacial development

Migración de neutrófilos en larvas de pez cebra expuestos a extractos de sofrito de tomate

Neutrophils migration in zebrafish larvae exposed to tomato sofrito extracts. The main of this study was to evaluate the anti-inflammatory activity of tomato sofrito extracts, as well as standard compounds present in the Mediterranean diet, using an optimized experimental model based on zebrafish larvae. Neutrophil migration in zebrafish larvae 96 hours post fertilization was induced by a cut in the caudal fin and enhanced by adding lipopolysaccharide and was visualized and quantified by image analysis. The anti-inflammatory effect of tomato extract and the compounds used was correlated by the percentage decrease in the migration of neutrophils. The results showed that, tomato extract showed a reduction in neutrophil migration of 40% compared to the control group. Moreover, chlorogenic acid and cyanidin present in tomato sofrito sauce showed a decrease in neutrophil migration of 66.7% and 62.5% respectively. These percentages are comparable to the results observed in trials with anti-inflammatory drugs such as indomethacin and piroxicam. The results show that tomato sofrito extract has possible anti-inflammatory activity demonstrated by the reduction of neutrophil migration, furthermore the model was sensitive and valid to be applied in complex food matrices

Assessment of Developmental Delay in the Zebrafish embryo Teratogenicity Assay

In this study we analyzed some aspects of the assessment of developmental delay in the zebrafish embryotoxicity/teratogenicity test and explored the suitability of acetylcholinesterase (AChE) activity as a biochemical marker and as a higher throughput alternative to morphological endpoints such as head-trunk angle, tail length and morphological score. Embryos were exposed from 4 to 52 h post-fertilization (hpf) to a selection of known embryotoxic/teratogen compounds (valproic acid, retinoic acid, caffeine, sodium salicylate, glucose, hydroxyurea, methoxyacetic acid, boric acid and paraoxon-methyl) over a concentration range. They were evaluated for AChE activity, head-trunk angle, tail length and several qualitative parameters integrated in a morphological score. In general, the different patterns of the concentration-response curves allowed distinguishing between chemicals that produced growth retardation (valproic and methoxyacetic acid) and chemicals that produced non-growth-delay related malformations. An acceptable correlation between the morphological score, AChE activity and head-trunk angle as markers of developmental delay was observed, being AChE activity particularly sensitive to detect delay in the absence of malformations

Evaluation of anti-inflammatory activity of food compounds using zebrafish

Podeu consultar el llibre complet a: http://hdl.handle.net/2445/128014The principal aim of this work was to optimize and apply a zebrafish experimental model for the screening of anti-inflammatory substances present in the Mediterranean diet. The zebrafish is an organism widely used in various fields of experimental biology. The inflammation is easily inducible, reproducible and visualized in their early stages of development. Specifically, the migration of neutrophils to the injured caudal fin, one of the first steps of the inflammatory response, is quantitatively measured by image analysis. The anti-inflammatory effect of natural compounds can be evaluated as a decrease of migration. Adverse effects triggered by inflammation are mainly mediated by reactive oxygen species. The anti-oxidant activity of compounds was evaluated in zebrafish embryo measuring their protective effect against tert-butyl hydroperoxide toxicity. Several phenolic compounds have been assayed. Our results showed that the compounds with the greatest decrease on neutrophil migration were chlorogenic acid and cyanidin. The activity of these two polyphenols was quite similar to that observed with anti-inflammatory drugs (indomethacin, piroxicam) and NADPH oxidase inhibitor compounds (dibenzoidolium, apocynin). The anti-inflammatory and the anti-oxidant activity of the assayed polyphenols did not show a clear correlation

Zebrafish as a model for developmental toxicity assessment

Podeu consultar el llibre complet a: http://hdl.handle.net/2445/67430The zebrafish embryo has emerged as promising alternative model for traditional in vivo developmental toxicological screening due to their advantageous characteristics as their small size and transparency. In this paper, we reviewed the applicability of the zebrafish embryo model in some relevant areas to human t oxicology as developmental toxicity, cardiovascular toxicity and neurotoxicity (behavioral assessment). Despite the promising results, further optimization and testing of more substances as well as a harmonized methodology is needed to streamline the metho ds and make the assay conducive to medium - throughput

Cardiovascular effects of PCB 126 (3,3',4,4',5-pentachlorobiphenyl) in zebrafish embryos and impact of co-exposure to redox modulating chemicals

The developing cardiovascular system of zebrafish is a sensitive target for many environmental pollutants, including dioxin-like compounds and pesticides. Some polychlorinated biphenyls (PCBs) can compromise the cardiovascular endothelial function by activating oxidative stress-sensitive signaling pathways. Therefore, we exposed zebrafish embryos to PCB126 or to several redox-modulating chemicals to study their ability to modulate the dysmorphogenesis produced by PCB126. PCB126 produced a concentration-dependent induction of pericardial edema and circulatory failure, and a concentration-dependent reduction of cardiac output and body length at 80 hours post fertilization (hpf). Among several modulators tested, the effects of PCB126 could be both positively and negatively modulated by different compounds; co-treatment with -tocopherol (vitamin E liposoluble) prevented the adverse effects of PCB126 in pericardial edema, whereas co-treatment with sodium nitroprusside (a vasodilator compound) significantly worsened PCB126 effects. Gene expression analysis showed an up-regulation of cyp1a, hsp70, and gstp1, indicative of PCB126 interaction with the aryl hydrocarbon receptor (AhR), while the transcription of antioxidant genes (sod1, sod2; cat and gpx1a) was not affected. Further studies are necessary to understand the role of oxidative stress in the developmental toxicity of low concentrations of PCB126 (25 nM). Our results give insights into the use of zebrafish embryos for exploring mechanisms underlying the oxidative potential of environmental pollutants

Modulation and Protection Effects of Antioxidant Compounds against Oxidant Induced Developmental Toxicity in Zebrafish

The antioxidant effect of compounds is regularly evaluated by in vitro assays that do not have the capability to predict in vivo protective activity or to determine their underlying mechanisms of action. The aim of this study was to develop an experimental system to evaluate the in vivo protective effects of different antioxidant compounds, based on the zebrafish embryo test. Zebrafish embryos were exposed to tert-butyl hydroperoxide (tBOOH), tetrachlorohydroquinone (TCHQ) and lipopolysaccharides from Escherichia coli (LPS), chemicals that are known inducers of oxidative stress in zebrafish. The developmental toxic effects (lethality or dysmorphogenesis) induced by these chemicals were modulated with n-acetyl l-cysteine and Nω-nitro l-arginine methyl ester hydrochloride, dimethyl maleate and dl-buthionine sulfoximine in order to validate the oxidant mechanism of oxidative stress inducers. The oxidant effects of tBOOH, TCHQ, and LPS were confirmed by the determination of significant differences in the comparison between the concentration-response curves of the oxidative stress inducers and of the modulators of antioxidant status. This concept was also applied to the study of the effects of well-known antioxidants, such as vitamin E, quercetin, and lipoic acid. Our results confirm the zebrafish model as an in vivo useful tool to test the protective effects of antioxidant compounds

Developmental effects and genotoxicity of ten water disinfection by-products in zebrafish

Disinfection by-products are contaminants produced during drinking water disinfection. Several DBPs have been implicated in a variety of toxic effects, mainly carcinogenic and genotoxic effects. Moreover, DBPs exposure has also been associated with an increased risk of developmental effects. In this study, the developmental toxicity and genotoxicity of 10 DBPs (4 trihalomethanes [THMs], 5 haloacetic acids [HAAs] and sodium bromate) in the zebrafish embryo model were evaluated. Embryos exposed for 72 hours were observed for different endpoints such as growth, hatching success, malformations and lethality. THMs exposure resulted in adverse developmental effects and a significant reduced tail length. Two HAAs, tribromoacetic acid and dichloroacetic acid, along with sodium bromate were found to cause a significant increase in malformation rate. Chloroform,chlorodibromomethane and sodium bromate produced a weak induction of DNA damage to whole embryos. However, developmental effects occurred at a range of concentrations (20 100 μg/mL)several orders of magnitude above the levels that can be attained in fetal blood in humans exposed to chlorinated water. In conclusion, the teratogenic and genotoxic activity observed by some DBPs in zebrafish reinforce the view that there is a weak capacity of disinfection products to cause developmental effects at environmentally relevant concentrations