Chlorfenapyr Induces Hepatotoxicity Associated With Oxidative Stress and Mitochondrial Dysfunction Involving Keap1/Nrf2 Signaling

Chlorfenapyr (CHL) is a widely used pyrrole insecticide, but its hepatotoxic effects and underlying mechanisms remain incompletely understood. This study investigated the toxic effects of CHL on rat liver and BRL-3A hepatocytes and explored the involvement of the Keap1/Nrf2 signaling pathway. Rats were administered CHL (10, 20, or 30 mg/kg) by oral gavage for 24 h, and BRL-3A cells were exposed to CHL (5, 10, or 50 μM). CHL treatment significantly increased the liver weight index and serum ALT and AST levels and induced hepatocyte swelling, degeneration, and apoptosis in rats, accompanied by reduced ATP content and decreased expression of mitochondrial proteins. Consistently, CHL exposure reduced cell viability, promoted apoptosis, and impaired mitochondrial function in BRL-3A cells. In both in vivo and in vitro models, CHL markedly increased ROS and MDA levels while decreasing SOD activity and GSH content, indicating severe oxidative stress and impaired antioxidant capacity. Mechanistically, CHL increased Keap1 expression and suppressed Nrf2 signaling, as evidenced by reduced expression of Nrf2 and its downstream antioxidant proteins HO-1 and NQO1, together with decreased nuclear accumulation of Nrf2. Furthermore, treatment with the Nrf2 activator tBHQ partially restored Nrf2 signaling, promoted nuclear translocation of Nrf2, and alleviated oxidative stress, mitochondrial dysfunction, and apoptosis in CHL-treated cells. These findings demonstrate that CHL induces hepatotoxicity associated with oxidative stress, mitochondrial dysfunction, and hepatocyte apoptosis, at least in part through disruption of the Keap1/Nrf2 signaling pathway, and suggest that activation of Nrf2 may represent a potential strategy for mitigating CHL-induced liver injury.