Xenoestrogen interference with sex-steroid binding proteins in plasma from arctic charr (Salvelinus alpinus L.)

We have previously identified a high-affinity sex?steroid binding protein (SBP) in plasma from male, female and juvenile Arctic charr (Salvelinus alpinus L.). This study focuses on interactions between Arctic charr SBP (acSBP) and several known or suspected xenoestrogens. The test compounds (ethinylestradiol, diethylstilbestrol, genistein, zearalenone, 4-t-octylphenol, bisphenol A and o,p'?DDT) were all able to displace tritiated 17/beta-estradiol from the sex-steroid binding site at the acSBP in a competitive and dose dependent manner. The acSBP affinities for the tested xenobiotics ranged over several orders of magnitude but were consistently lower than that of 17(3?estradiol (about 100-1000000-fold less potent). The relative binding affinities (RBAs) for xenoestrogens were independent of both sex and maturation status, as well as individual variations of acSBP binding affinity.