Effect of 17α-ethinylestradiol (EE2) as a reproductive endocrine disruptor in the fish Aequidens metae

Abstract

The 17α-ethinylestradiol (EE2) is a synthetic steroid that interferes with the reproductive endocrine system of fish. This study evaluated the effect of EE2 as a possible endocrine disruptor in adult Aequidens metae females and males exposed to 0.5, 5, 50, and 250 ng/L for 21 days. Negative control and solvent control (ethanol) were included. After exposure, blood was collected to determine plasma calcium and phosphorus, and somatic indices and histology changes were evaluated in the gonads and liver. The gonadosomatic and hepatosomatic indices did not present significant differences. At histological level, congestion, interstitial fibrosis, apoptosis, atresia, and vitellogenic material were found in the ovary. At the testicular level, accumulation of melanomacrophage material, testicular degeneration, interstitial fibrosis, atrophy and thickening of the interstitial wall were observed. In the liver, in both sexes, was observed greater degenerative pyknosis, activation of macrophages, apoptosis, infiltrations, dilatation and congestion compared with the control groups. Females did not show significant differences in plasma calcium and phosphorus between treatments. The males exposed to the three highest EE2 concentrations had significantly higher values in plasma calcium compared to control group. Regarding plasma phosphorus, in males exposed to 250 ng/L there were differences compared to control groups. The results allow inferring that this species is sensitive to endocrine disruption effects generated by EE2 and that the determination of biochemical parameters such as plasma calcium and phosphorus ions can be used as additional biomarkers of the health status of fish exposed to xenobiotics.