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DENAMIC: screening developmental neurotoxicity of low-dose chemical mixtures



Principle investigators:
Project leader:
Marieke Meijer, M.Sc.
Milou Dingemans, Ph.D.
R.H.S. Westerink, Ph.D.
Milou Dingemans, Ph.D.
Project description: 

This research takes place within the multi-disciplinary EU collaborative project DENAMIC (Developmental Neurotoxicity Assessment of Mixtures in Children). The aim of this project is to evaluate and develop screening methods for chemical-induced developmental neurotoxicity and to improve assessment of exposures and effects. To this aim a dual approach is followed by the DENAMIC consortium consisting of 13 partners (universities, research institutes and SMEs). Hazard characterization for developmental neurotoxicity by chemicals and low-dose mixtures using newly developed experimental approaches (in vitro and in vivo studies) will be combined with the study of associations between neurodevelopment and exposure to these chemicals in large EU epidemiological cohorts. In both the experimental and epidemiological part of DENAMIC, biomarkers for developmental neurotoxicity will be developed. There is particular attention for the exposure to environmental pollutants and possible neurotoxic effects at low doses and in mixtures. The Neurotoxicology Research Group at IRAS will focus on the effects of single chemicals and mixtures in in vitro screening tools for developmental neurotoxicity.

A reference set of chemicals will be used for the evaluation of in vitro screens for developmental neurotoxicity. The reference set consists of known (developmentally) neurotoxic compounds as well as emerging chemicals for which the (developmentally) neurotoxic potential is suspected or unknown. Effects of the reference chemicals on cell viability of neuronotypic cell lines will be performed for concentration range-finding and as initial screening of toxicity. Based on these results, chemicals will be selected for additional screening for inter- and intracellular neurotoxicity and for effect assessment of in vitro developmental processes using fluorescent imaging approaches. Binary mixtures and human milk extracts are included to mimic real-life exposure situations and to investigate mixture toxicity.In addition to neuronotypic cell lines, neural progenitor cells will be used as an in vitro model for the developing brain. Furthermore, for evaluation of the in vitro tools, synaptic plasticity will be investigated ex vivo in brain tissues from developmentally exposed mice.
Through all stages of life, including prenatal development, humans are exposed to numerous chemicals via the environment. Various recent epidemiological studies indicate that low-dose chemical exposure during brain development can have adverse effects on cognitive development in childhood. Evidence exists that environmental exposure to chemicals also plays a role in (subclinical) effects on learning and risk for developmental disorders in children (e.g. ADHD, autism spectrum disorders and anxiety disorders). The DENAMIC project is ultimately focused on reducing such effects of environmental exposure to low-dose chemical mixtures in children by improving screening tools for exposure and effect assessment.
Recent publications:
- Dingemans MML, Schutte MG, Wiersma DM, de Groot A, van Kleef RGDM, Wijnolts FM, Westerink RHS (2016). Chronic 14-day exposure to insecticides or methylmercury modulates neuronal activity in primary rat cortical cultures. Neurotoxicology 57, 194-202.
- Hendriks, H.S., Koolen, L.A., Dingemans, M.M.L., Viberg, H., Lee, I., Leonards, P.E., Ramakers, G.M., Westerink, R.H.S. Effects of neonatal exposure to the flame retardant tetrabromobisphenol-A, aluminum diethylphosphinate or zinc stannate on long-term potentiation and synaptic protein levels in mice. Archives of Toxicology 89, 2345-2354 (2015).
- Meijer, M., Brandsema, J.A., Nieuwenhuis, D., Wijnolts, F.M.J., Dingemans, M.M.L., Westerink, R.H.S. Inhibition of Voltage-Gated Calcium Channels After Subchronic and Repeated Exposure of PC12 Cells to Different Classes of Insecticides. Toxicological Sciences 147, 607-617.
- Meijer, M., Hendriks, H.S., Heusinkveld, H.J., Langeveld, W.T., Westerink, R.H.S. Comparison of plate reader-based methods with fluorescence microscopy for measurements of intracellular calcium levels for the assessment of in vitro neurotoxicity. Neurotoxicology 45, 31-37 (2014).
- Meijer, M., Dingemans, M.M.L., van den Berg, M., Westerink, R.H.S. Inhibition of voltage-gated calcium channels as common mode of action for (mixtures of) distinct classes of insecticides. Toxicological Sciences 141, 103-111 (2014).
- Meijer, M., Hamers, T., Westerink, R.H.S. Acute disturbance of calcium homeostasis in PC12 cells as a novel mechanism of action for (sub)micromolar concentrations of organophosphate insecticides. Neurotoxicology 43, 110-116 (2014).
- Gassmann, K., Schreiber, T., Dingemans, M.M.L., Krause, G., Roderigo, C., Giersiefer, S., Schuwald, J., Moors, M., Unfried, K., Bergman, A., Westerink, R.H.S., Rose, C.R., Fritsche, E. BDE-47 and 6-OH-BDE-47 modulate calcium homeostasis in primary fetal human neural progenitor cells via ryanodine receptor-independent mechanisms. Archives of Toxicology 88, 1537-1548 (2014).
- de Groot, M.W.G.D.M., Dingemans, M.M.L., Rus, K.H., de Groot, A., Westerink, R.H.S. Characterization of calcium responses and electrical activity in differentiating mouse neural progenitor cells in vitro. Toxicological Sciences 137, 428-435 (2014).
- de Groot, M.W.G.D.M., Westerink, R.H.S., Dingemans, M.M.L. Don´t judge a neuron only by its cover: neuronal function in in vitro developmental neurotoxicity testing. Toxicological Sciences 132, 1-7 (2013).
- Langeveld, W.T., Meijer, M., Westerink, R.H.S. Differential effects of 20 non-dioxin-like PCBs on basal and depolarisation-evoked intracellular calcium levels in PC12 cells. Toxicological Sciences 126, 487-496 (2012).
- Hondebrink, L., Meulenbelt, J., Rietjens, S.J., Meijer, M., Westerink, R.H.S. Methamphetamine, amphetamine, MDMA ('ecstasy'), MDA and mCPP modulate electrical and cholinergic input in PC12 cells. Neurotoxicology 33, 255-260 (2012).
- Dingemans, M.M.L., van den Berg, M., Westerink, R.H.S. Neurotoxicity of PBDEs: Dingemans et al. respond. Environmental Health Perspectives 119, a331-a332 (2011).
-  Dingemans, M.M.L., van den Berg, M., Westerink, R.H.S. Neurotoxicity of brominated flame retardants: (in-)direct effects of parent and hydroxylated polybrominated diphenyl ethers on the (developing) nervous system. Environmental Health Perspectives 119, 900-907 (2011).
- Hondebrink, L., Meulenbelt, J., Meijer, M., van den Berg, M., Westerink, R.H.S. High concentrations of MDMA (‘ecstasy’) and its metabolite MDA inhibit calcium influx and depolarization-evoked vesicular dopamine release in PC12 cells. Neuropharmacology 61, 202-208 (2011).
- Dingemans, M.M.L. (2010). Neurotoxicity of PBDEs and metabolites: concern for the developing brain? ISBN 978-90-393-5290-8. Awarded by the Netherlands Society for Toxicology with the ‘Joep van den Bercken Prize‘ for the best PhD thesis of the year in the field of Toxicology.
- Dingemans, M.M.L., Heusinkveld, H.J., van den Berg, M., Bergman, A., Westerink, R.H.S. Bromination pattern of hydroxylated metabolites of BDE-47 affects their potency to release calcium from intracellular stores in PC12 cells. Environmental Health Perspectives 118, 519-525 (2010).
- Dingemans, M.M.L., van den Berg, M., Bergman, A., Westerink, R.H.S. Calcium-related processes involved in the inhibition of depolarization-evoked calcium increase by hydroxylated PBDEs in PC12 cells. Toxicological Sciences 114, 302-309 (2010).
- Dingemans, M.M.L., Heusinkveld, H.J., de Groot, A., Bergman, Å., van den Berg, M., Westerink, R.H.S.  Hexabromocyclododecane inhibits depolarization-induced increase in intracellular calcium levels and neurotransmitter release in PC12 cells. Toxicological Sciences 107, 490-497 (2009).
- Dingemans, M.M.L., de Groot, A., van Kleef, R.G.D.M., Bergman, Å., van den Berg, M., Vijverberg, H.P.M., Westerink, R.H.S. Hydroxylation Increases the Neurotoxic Potential of BDE-47 to Affect Exocytosis and Calcium Homeostasis in PC12 Cells. Environmental Health Perspectives 116, 637-643 (2008).
- Dingemans, M.M.L., Ramakers, G.M.J., Gardoni, F., van Kleef, R.G.D.M., Bergman, Å., Di Luca, M., van den Berg, M., Westerink, R.H.S., Vijverberg, H.P.M. Neonatal exposure to brominated flame retardant BDE-47 reduces long-term potentiation and postsynaptic protein levels in mouse hippocampus. Environmental Health Perspectives, 115, 865-870 (2007).
- Prof. E. Fritsche, Institut für umweltmedizinische Forschung, Heinrich-Heine-Universität Düsseldorf, Germany
- Dr. G.M.J. Ramakers, Rudolf Magnus Institute, University Medical Centre Utrecht
- DENAMIC partners