الفهرس 
ZusammenfassungOnly 14 pages are availabe for public view
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Abstract
Parkinson’s disease (PD) is the second most common neurodegenerative disorder of the elderly affecting approximately 1% of the population older than 60 years old. Numerous epidemiological and animal studies have supported the hypothesis that exposure to pesticides can increase the risk for developing PD, however, the results of these studies are not conclusive. Therefore, the European Food Safety Authority (EFSA) recommended the reassessment of the hypothesis that some pesticides may cause Parkinsonian motor deficits (PMD) using the adverse outcome pathway (AOP) concept. Based on the recommendations of EFSA, this work aimed to establish an AOP-informed and mode-of-action-based human in vitro test battery for hazard identification. Therefore, two test systems were established to obtain dopaminergic neurons, i.e. differentiated human induced pluripotent stem cells (hiPSCs) and Lund human mesencephalic (LUHMES) cells. A test battery based on dopaminergic neurons differentiated from LUHMES cells was successfully established. This human cellular model was used to establish assays based on key events (KEs) of the proposed AOPs using two model compounds for PMD, rotenone and paraquat. Those KEs are represented by the assessment of cell viability based on reductase activity and adenosine triphosphate (ATP) production, proteasomal activity, cytotoxicity and apoptosis. In order to determine the specificity of this test battery, the negative compounds saccharin and diethylene glycol were tested. The concentration- and time-dependent effects of the commonly used organophosphate pesticides chlorpyrifos, parathion, malathion and dichlorvos, as well as their oxon metabolites were investigated using this test battery. Moreover, changes of the metabolome during neuronal differentiation and in response to pesticides on differentiated LUHMES cells were assessed. All organophosphate pesticides and their metabolites affect at least cytotoxicity and cell viability based on reductase activity and ATP levels in the test battery. Thereby, the activity profiles of chlorpyrifos and parathion are similar to that of rotenone, while the effects of malathion and dichlorvos resemble paraquat responses. Furthermore, clear metabolome changes were detected during the neuronal differentiation of LUHMES cells and after exposure to pesticides, which indicate the potential value of implementing this approach for the toxicological assessments in the future. Notably, LUHMES cells seem to be a suitable model to identify if a compound affects early KEs of the AOP leading to PMD. However, future work needs to shed light on the specificity of the effects for dopaminergic neurons.