Distribution and cellular localization of sea bream estrogen receptors in calcified tissues

In teleost fish, estradiol has been shown to induce calcium mobilization from internal stores, in particular the scales. In the present study, we have localized the estrogen receptor proteins (α, βa and βb) in the scales of juvenile and adult sea bream, using immunohistochemistry with ER isoform-specific antibodies. The ERs co-localized in cells of the scale posterior region that also expressed TRACP, the putative osteoclasts. These results suggest that the calcium mobilising action of estradiol on fish scales is via its direct action on osteoclasts.European Social Fund and National Funds under the project POCTI/CVT/39355/2001 from the Portuguese Foundation for Science and Technology (FCT). PP was funded by the FCT grant POCTI/SFRH/ BD/5198/2001. MDE was in receipt of a PRODEP grant, Programa de Desenvolvimento Educativo para Portugal (medida5/concurso 2/acção5.3/2001)