Chlorpyrifos-induced dopaminergic damage in Drosophila melanogaster assessed by gene expression, AChE assay, and negative geotaxis using a new feeding device

We developed a new and simple feeding device for Drosophila melanogaster. In addition, we tested three negative geotaxis methods (measuring the percentage of the flies able to climb 8 cm in 8 s, measuring the distance climbed in 3 s, and measuring the distance climbed in 8 s). The flies were exposed to chlorpyrifos (CPF) using the new feeding device. Our results demonstrated that the three methods for measuring negative geotaxis could be used interchangeably with respect to the needs and conditions of the experiments; however, we recommend the 8 s method with PAST software because the other two methods were carried out using manual measurements. The use of this free software makes the process more accurate with no additional cost. We found that CPF caused impairment in locomotor activity, reduction in AChE activity, and disturbance of the dopaminergic pathways in D. melanogaster, suggesting that CPF toxicity is not confined to the cholinergic system. This study provides a new system to study neurodegenerative damage using a user-friendly and no-cost software for measuring climbing activity in D. melanogaster.