Oxidative Stress in Kidney of Zebrafish due to Individual and Combined Exposure to Amoxicillin, Arsenic, and Fluoride: Involving Nrf2-Keap1-ARE Pathway.

Abstract

Toxic manifestations of different antibiotics and metal compounds have been studied comprehensively in the last decades; however, their co-toxicity on aquatic organisms is poorly investigated. This study aimed to evaluate the oxidative stress imposed on zebrafish kidney tissue when exposed to amoxicillin (AMX, 10 μg/L) alone or in combination with 50 μg/L of As₂O₃ (equivalent to 37.87 μg/L of As) and/or 15 mg/L of NaF (equivalent to 6.8 mg/L of F) for 15 days. We observed increased levels of cellular ROS, MDA, and GSH along with increased activity of CAT enzyme in all the treated groups. Disrupted histoarchitecture, including degeneration of tubular cells, vacuolation, and necrotic spots, was indicative of oxidative damage. mRNA expression of stress responsive genes like nrf2, gpx1, hsp70, keap1, nqo1, cat, and ho1 corroborated the data. Translocation of Nrf2 from cytoplasm to nucleus and its subsequent expression was higher for all the treated groups. Moreover, the mixture effects of AMX + As + F were more severe than the other combinations, while unique exposure with AMX had minimum effects. Highlighting the involvement of the Nrf2-Keap1-ARE pathway, these findings make us aware of the synergistic response of AMX, As, and F in the ecosystem, putting forward a great threat to humankind.