Copper affect the multixenobiotic resistance mechanism (MXR) in embryo and larvae of Rhamdia quelen

Abstract

P-glycoproteins (P-gp) and Multidrug resistance protein (MRP) represent a family of ABC (ATP-binding cassette) transporters responsible for multixenobiotic resistance mechanism (MXR) in aquatic organisms. In the current study the modulation of P-gp and MRP proteins was evaluated in embryo and larvae of Rhamdia quelen fish species exposed to copper. Adult females were exposed by gavage during 60 days to copper (5 mg Cu kg-1) and eggs, embryos, and larvae from exposed and unexposed females were exposed to 30 mg Cu L-1. The activity of ABC transporters was accessed via calcein accumulation assay using the specific inhibitors: Verapamil (P-gp) and MK571 (MRP). P-gp activity was detected in all analyzed stages whereas MRP activity was observed after 36 and 96 hpf. Oocytes from females previously exposed and larvae stages (36 and 96 hpf) accumulated less calcein than no exposed oocytes, showing higher ABC transporters activity. In individuals exposed to copper, a higher inhibitory effect was observed 1 hpf. The modulation of ABC transporter proteins is time dependent throughout the development, and the initial stages are more sensible to copper. These findings highlight the MXR mechanism as a biomarker of pollutant exposure in early stages of development of R. quelen.