Oxidative Stress Toxicogenomics Behavioral Toxicology Environmental Toxicology

Given the widespread global use of hair dyes, which contain chemicals like aromatic amines and oxidative agents, understanding their toxic potential is a critical component of assessing human safety. Drosophila melanogaster served as a model organism due to its well-characterized genome, conserved neurological pathways, and ease of genetic tractability. The flies were exposed to three treatment concentrations of the hair dye (0.05%, 0.5%, and 2.0%). The study assessed overall survival rates and observed climbing ability of the flies using the negative geotaxis assay. Flies were exposed to various concentrations of the dye through dietary administration, and survival was monitored over a 7-day period for the pilot study and a 5-day period for the main study. The relative expression of several key genes including Spitz(Spi), Wingless(Wnt), Eiger(egr), Forkhead box(FOXO), Hedgehog(HH), and Kelch-like ECH-associate protein 1(Keap1) was analyzed. Results demonstrated a dose-dependent response of the organism. The locomotor behavior analysis showed declining climbing ability of the flies at increasing concentrations. The Spi gene, associated with the EGFR pathway, showed a significant increase at the highest (2.0%) concentration. Wnt gene was significantly decreased at the 0.5% and 2.0% concentrations while Eiger gene was increased. The transcription factor FOXO was decreased while the signaling gene HH was significantly increased at high concentrations, indicating the activation of stress-induced and developmental response mechanisms. Conversely, the stress regulator Keap1, involved in the Nrf2 pathway was decreased at the 0.5% and 2.0% concentrations. These findings collectively establish that exposure to the hair dye induces significant neurotoxicity and disturbs fundamental regulatory mechanisms in Drosophila melanogaster, highlighting the need for accurate toxicological evaluation of these cosmetic products.