Estrogen receptor-β in quail: Cloning, tissue expression and neuroanatomical distribution

A partial estrogen receptor-β (ERβ) cDNA had been previously cloned and sequenced in Japanese quail. The 3'- and 5'-rapid amplification of cDNA ends techniques were used here to identify a cDNA sequence of the quail ERβ that contains a complete open reading frame. For the first time in an avian species, this cDNA sequence and the corresponding amino acid sequence are described. They are compared with the known ERβ sequences previously described in mammals and with the ERα sequences identified in a selection of mammalian and avian species. The analysis by Northern blotting of the ERβ mRNA expression in the brain and kidneys revealed the presence of several transcripts. The presence of ERβ identified by reverse transcriptase- polymerase chain reaction demonstrated a widespread distribution quite different from the distribution of ERα. The complete neuroanatomical distribution of ERβ mRNA as determined by in situ hybridization with ³⁵S- and ³³P-labeled oligoprobes is also presented. Transcripts are present in many nuclei implicated in the control of reproduction such as the medial preoptic nucleus, the nucleus striae terminalis, and the nucleus taeniae, the avian homologue of the amygdala. These data demonstrate the presence of ERβ in a nonmammalian species and indicate that the (neuro)-anatomical distribution of this receptor type has been conserved in these two classes of vertebrates. The role of this receptor in the control of reproduction and other physiological processes should now be investigated.