Relationship between permeability glycoprotein (P-gp) gene expression and enrofloxacin metabolism in Nile Tilapia

The aim of this study was to analyze the influence of permeability glycoprotein (P-gp) gene expression on enrofloxacin (ENR) metabolism in aquatic animals. Nile Tilapia Oreochomis niloticus were fed different doses of ENR ranging from 0 to 80 mg/kg. The P-gp gene expression levels were determined by quantitative real-time PCR (qRT-PCR) at indicated time points after drug administration. Drug metabolism was determined by HPLC. The P-gp gene expression in liver and kidney was greatly enhanced 30 min after ENR administration at 40 mg/kg, peaked 3 h after drug administration, and then gradually decreased. Thirty minutes after a single oral administration of ENR (0, 20, 40, or 80 mg/kg), the P-gp gene expression increased in a dose-dependent manner. The P-gp gene expression levels in the kidney were significantly higher than those in the liver. Additionally, the metabolic rate of ENR in kidney was more rapid than that in liver. Furthermore, a close correlation was found between P-gp gene expression and ENR concentrations. These results suggest that P-gp may be involved in the ENR metabolism process in Nile Tilapia, providing a novel model for the potential utility of gene expression and drug metabolism studies in aquatic animals.