Estradiol-17β and Bisphenol a Differentially Affect Growth and Mineralization in Early Life Stages of Seabass

Abstract

Natural and synthetic estrogens are contaminants present in aquatic ecosystems. They can have significant consequences on the estrogen-sensitive functions of larval organisms, including skeletal development and growth. Synthetic polyphenols represent a group of environmental xenoestrogens capable of binding the receptors for the natural hormone estradiol-17β (E2). To better understand how (xeno-)estrogens can affect the skeleton in fish species with high ecological and commercial interest, young larvae of the seabass were experimentally exposed for 7 days to E2 and Bisphenol A (BPA), both used at the regulatory concentration of surface water quality or at a concentration 100 times higher. Skeletal mineralization levels were evaluated using Alizarin red staining, and expression of several genes playing key roles in growth, skeletogenesis and estrogen signaling pathways was assessed by qPCR. Our results show that E2 exerts an overall negative effect on skeletal mineralization at environmental concentrations, correlated with an increase in the expression of genes associated only with osteoblast bone cells. BPA exposure inhibited mineralization with less severe effects and modified bone homeostasis by regulating the expression of gene encoding osteoblasts and osteoclasts markers. Our results demonstrate biological effect of environmentally relevant concentration of E2 and BPA on the skeletal growth of larval seabass.

Keywords: Bone mineralization, Bisphenol A, Estradiol-17β, Estrogen signaling, Seabass Dicentrarchus labrax