Effects of pyridaben on the spleen and T lymphocytes and intervention strategy in grass carp (Ctenopharyngodon idella).

The widespread use of pyridaben (PDB) poses serious threat to aquatic organism health. 6-Gingerol, a bioactive component of ginger, has been demonstrated to possess both antioxidant and immunomodulatory properties. However, the effects of spleen injury of PDB in aquatic species and the potential mitigating effects of 6-Gingerol remain insufficiently characterized. The present study aimed to characterize the toxic effects of PDB on the spleen of grass carp and to evaluate whether 6-Gingerol could effectively counteract PDB-induced toxicity. The results showed that PDB exposure could induce splenic erythrocyte extravasation, vacuolization, interstitial arrangement loose and apoptosis. Flow cytometry further revealed that PDB exposure decreased the proportion of splenic CD4 T-lymphocytes by 9.47% while increasing CD8 T-lymphocytes by 5.91%. In contrast, 6-Gingerol treatment reversed above pathological spleen injury and recover splenic CD4/CD8 T lymphocytes disturbance. Meanwhile, PDB exposure could disrupt mitochondrial morphology in grass carp spleen, accompanied by the suppression of glycometabolism-related genes and reduction in ATP levels. In contrast, treatment with 6-Gingerol effectively mitigated these PDB-induced mitochondrial dysfunctions. Further analyses confirm that 6-Gingerol inhibits PDB-induced reactive oxygen species (ROS) overload and 8-hydroxy-2'-deoxyguanosine (8-OHdG) overproduction, accompanied restoration of Nrf2 nuclear accumulation. Importantly, 6-Gingerol positively regulates AMP-activated protein kinase (AMPK) to counteract PDB-induced decline of peroxisome proliferator-activated receptor-gamma coactivator 1 α (PGC1α) in spleen. In conclusion, our results suggest that 6-Gingerol alleviates PDB-induced immunotoxicity and protects mitochondrial function in grass carp, an effect associated with the regulation of the AMPK signaling pathway. These findings provide theoretical basis for understanding the aquatic toxicity induced by PDB and offer new insights into the protective strategy of 6-Gingerol against toxic substances.