The Protective Effect of Naringenin against Lead-Induced Hepatotoxicity in Rats: Mechanisms Involving Oxidative Stress Mitigation, Activation of PINK1/Parkin and Nrf2/NQO1 Pathways, and Autophagy Induction.

Lead (Pb), a persistent and highly toxic environmental contaminant, induces severe multi-organ toxicity, with the liver as a primary target. Naringenin (Nar), a natural flavonoid with established antioxidant properties, shows potential in mitigating chemical-induced liver injury; however, its protective mechanism against Pb hepatotoxicity remains unclear. This study investigated the hepatoprotective effects and underlying mechanisms of Nar in Pb-exposed rats. Thirty-six five-week-old male Sprague-Dawley rats were randomly assigned to six groups (n = 6): control, three Pb-treated groups (15, 30, and 60 mg/kg), co-treatment group (60 mg/kg Pb + 50 mg/kg Nar), and Nar-alone group (50 mg/kg). After 8 weeks, Pb exposure induced significant liver injury, evidenced by histopathological lesions (e.g., central venous congestion and inflammation), elevated serum levels of ALT, AST, and LDH, and oxidative stress (increased MDA; decreased CAT, T-SOD, and GSH). At the molecular level, Pb exposure suppressed the Nrf2/NQO1 pathway, upregulated Keap1, and impaired autophagic flux, as indicated by a decreased LC3-II/LC3-I ratio, accumulated p62, and a disrupted PINK1/Parkin pathway. Corroborating the impaired flux, transmission electron microscopy (TEM) revealed an accumulation of autophagic vacuoles, indicative of blocked autophagic degradation. Crucially, Nar co-treatment effectively mitigated these Pb-induced disturbances by activating the Nrf2/NQO1 pathway to counteract oxidative stress and restored autophagic flux, which was supported by the reversal of p62 accumulation and normalization of the LC3-II/LC3-I ratio. In conclusion, Nar protects against Pb-induced hepatotoxicity by concurrently alleviating oxidative stress and restoring autophagic function, supporting its potential as a therapeutic agent.