Pyrroloquinoline quinone promotes growth and intestinal health and alleviates tris(1,3-dichloro-2-propyl) phosphate-induced hepatic oxidative stress in zebrafish

Pyrroloquinoline quinone (PQQ) is a newly discovered redox coenzyme possessing multiple biological activities, whose role in nutritional and physiological regulation in fish remains elusive. In this study, we explored how the dietary PQQ influenced the growth, intestinal health and oxidative stress of liver triggered by tris(1,3-dichloro-2-propyl) phosphate (TDCPP) in zebrafish, which was accomplished through a long-term feeding trial (experiment 1) and a short-term stress trial (experiment 2). In experiment 1, two-month-old zebrafish were fed experimental diets either involving 0.4 mg/kg (low PQQ, LP) or 1.6 mg/kg PQQ center dot Na2 (high PQQ, HP), or a basal diet (CNT) for four weeks. It showed that compared to the zebrafish in the CNT group, those in the LP and HP groups exhibited remarkably improved growth performance, whose feed conversion ratio was lower, while specific growth rate and weight gain rate higher. No significant intestinal pathological symptoms were found among groups, albeit the prominently increased villus height of zebrafish in LP and HP groups than the CNT zebrafish. Dietary PQQ led to great phylum-and genus-level modulation of intestinal microflora and made it more balanced. In experiment 2, four-month-old adult zebrafish were fed a basal diet (control group), a basal diet under TDCPP exposure (TDCPP group), a HP diet under TDCPP exposure (TDCPP+PQQ group), or a HP diet (PQQ group) for one week. After the stress trial, significant intrahepatic pathological symptoms were found in the TDCPP group, while TDCPP+PQQ and PQQ groups exhibited no significant stress injury. Further analysis implied that dietary PQQ significantly alleviated the TDCPP-triggered intrahepatic oxidative stress of zebrafish by elevating the antioxidation-related gene levels, potentiating the antioxidant enzyme activities and maintaining appropriate level of apoptosis. Taken together, this study suggested that PQQ could improve growth performance and in-testinal health and alleviate the TDCPP-induced liver oxidative stress in zebrafish.