COLLETTE, M.; ANCTIL, M.; Univ. de Montr�al, Montr�al: Presence of estrogen receptor-like immunoreactivities in the cnidarian Renilla koellikeri

Steroid hormones such as estrogens were recently reported in the sea pansy, Renilla koellikeri, and in other anthozoans (corals). Although a role for estrogens in the reproduction of the sea pansy and of scleractinian corals has been proposed, no direct evidence for such a role has yet been produced. In an attempt to identify potential functional targets for an estrogen at the cellular level, we used antibodies against mammalian estrogen receptors to map the distribution of sea pansy estrogen-like receptors by immunohistochemistry. By using antibodies against two different peptide fragments of the human estrogen receptor (hER), we visualized hER-like immunoreactivity in sensory cells of the ectoderm and in mesogleal neurons proximal to the endodermal muscles. Both antibodies reacted with these two types of neurons. Immunoreactivity was strongest in the ectoderm of the whole animal, especially in sensory cells of polyp tentacles. No immunoreactivity was found in gonad tissues. Instead of a role in reproduction, these results suggest a neurotrophic role for estrogens, at least in some subsets of sea pansy neurons, such as has been previously reported for the mammalian central nervous system. As the sea pansy belongs to the most primitive phylum in which nervous systems are present, these results seem to suggest that estrogen receptors were conserved across phylogeny. (Supported by NSERC of Canada to M.A.)