Silybin mitigated liver and brain damage after difenoconazole exposure: Crosstalk between oxidative stress, inflammation, ferroptosis and apoptosis.

Long-term residue of difenoconazole (DFZ) in the environment caused multiple organ damage to aquatic organisms. Due to the potential hepatoprotective and neuroprotective properties of silybin (SIL), we hypothesized that SIL could alleviate growth inhibition, liver, and brain damage in carp induced by DFZ exposure. The in vivo experiments were divided into the Control group, the SIL group, the DFZ group and the DFZ + SIL group. The exposure concentration of DFZ was 0.39 mg/L, and the therapeutic dose of SIL was 400 mg/kg. The whole experiment lasted for 30 days. SIL was also found to reduce hepatic injury and lipid metabolism based on H&E staining, oil red O staining, and measurement of serum and liver tissue levels of ALT, AST, LDH, TG, and TC. Similarly, SIL reduced brain damage after DFZ exposure, according to H&E staining and detection transcription level of the ZO-1, ZO-2, occludin, and Claudin7 in carp brain. In terms of mechanism, the results showed that SIL inhibited the excessive production of ROS in liver and brain tissues, increased the activity of antioxidant enzymes (T-AOC, SOD, CAT) and resist oxidative stress. Also, SIL promoted the production of anti-inflammatory factors (TGF-β1 and IL-10) and inhibited the expression of pro-inflammatory factors (TNF-α and IL-6) to reduce the inflammatory response in liver and brain tissues caused by DFZ. ln terms of ferroptosis, by lowering iron levels, upregulating ferroptosis-related genes (GPX4, SIC7A11, GCLC), and downregulating the expression of NCOA4, STEAP3, COX2, and P53, SIL was able to inhibit ferroptosis of liver and brain tissues of carp. In addition, SIL restored the reduced mitochondrial membrane potential (MMP) level and inhibited apoptosis as measured by MMP level detection, TUNEL staining, and apoptosis gene transcript levels. In this study, we analyzed the interactions between genes and proteins associated with oxidative stress, inflammation, ferroptosis and apoptosis using the String database and ranked the nodes in the network using the Cytoscape plugin Cytohubba, and found that P53, Caspase3, TNF-α, IL-6 and Bcl-2 were the key hub genes. Our study not only revealed the multiple pharmacological activities of SIL, but also provided a reference for the prevention and reduction pesticide hazards to aquatic organisms.