Protective effect of quercetin on carp cardiac damage caused by difenoconazole via alleviating oxidative damage, inflammatory responses, and apoptosis

Pollution of aquatic environment by difenoconazole (DFZ) significantly affects survival and safety of freshwater aquaculture. Due to its anti-inflammatory and antioxidant properties, plant-derived quercetin (QUE) is often used as a dietary supplement. The main purpose of this study was to explore the protective effect of QUE on heart damage caused by exposure to pesticide DFZ and the potential mechanisms of these effects. This study found that QUE could effectively reduce the myocardial enzyme spectrum index of carp after exposure to DFZ, increase the levels of total antioxidant capacity (T-AOC), glutathione (GSH), and catalase (CAT), inhibit the content of malondialdehyde (MDA), and increase the transcription levels of superoxide dismutase (sod), glutathione peroxidase (gsh-px), and cat. By reducing the expression of keap1, QUE increased the transcription levels of nrf2 and nqo-1, reduced the production of reactive oxygen species (ROS) in the heart after exposure to DFZ, and restored the redox homeostasis of the heart. QUE upregulated the expression of anti-inflammatory cytokines il-10 and tgf-β1 levels, downregulated the transcription levels of pro-inflammatory factor inos, il-1β, il-6 and tnf-α, and alleviated the in vivo redox imbalance caused by exposure to DFZ, leading to myocardial interstitial inflammatory cell infiltration. The results showed that QUE inhibited the apoptosis after exposure to DFZ by affecting the expression of apoptotic factors in the mitochondrial apoptotic pathway. In summary, QUE can effectively decrease myocardial injury caused by exposure to DFZ in aquatic environment. •The pesticide difenoconazole can cause carp cardiac pathological damage.•Quercetin can reduce cardiac tissue damage induced by difenoconazole.•Quercetin may reduce oxidative stress, inflammation and apoptosis.