Estrogen Receptor- in Quail: Cloning, Tissue Expression and Neuroanatomical Distribution Agne ` s Foidart, 1 Bernard Lakaye, 1 Thierry Grisar, 1 Gregory F. Ball, 2 Jacques Balthazart 1 1 Laboratory of Biochemistry, University of Lie ` ge, 17 place Delcour, Bat. L1, B-4020 Lie ` ge, Belgium 2 Department of Psychology; Behavioral Neuroendocrinology Group, Johns Hopkins University, Baltimore, Maryland 21218 Received 10 December 1998; accepted 3 March 1999 ABSTRACT: A partial estrogen receptor- (ER) 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 ER that contains a com- plete 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 ER sequences previously described in mammals and with the ER sequences identified in a selection of mammalian and avian species. The analysis by Northern blotting of the ER mRNA expression in the brain and kidneys revealed the presence of several transcripts. The presence of ER identified by reverse transcriptase–polymerase chain reaction demonstrated a widespread distribution quite different from the dis- tribution of ER. The complete neuroanatomical distri- bution of ER mRNA as determined by in situ hybrid- ization with 35 S- and 33 P-labeled oligoprobes is also presented. Transcripts are present in many nuclei im- plicated in the control of reproduction such as the me- dial preoptic nucleus, the nucleus striae terminalis, and the nucleus taeniae, the avian homologue of the amyg- dala. These data demonstrate the presence of ER 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. © 1999 John Wiley & Sons, Inc. J Neurobiol 40: 327–342, 1999 Keywords: estrogen receptor-; ER mRNA; in situ hybridization; northern blot; RT-PCR; hypothalamus; neuroanatomical distribution; Japanese quail; Coturnix japonica Estrogens play a key role in the control of female and male reproductive physiology, of sexual behavior as well as other physiological process such as bone cal- cification, memory, or cognition (McEwen et al., 1997; Cooke et al., 1998). However, until recently, there has been some confusion about the mechanisms of estrogen action given that estrogens have biological effects in tissues such as the telencephalon or bladder that appear to be devoid of the intracellular receptors needed for physiological responses to estrogen. Al- though estrogens can have rapid nongenomic effects in the central nervous system (Ramirez et al., 1996; Mermelstein et al., 1996; Joe ¨ls, 1997), most of their actions during development and in adulthood are thought to be mediated by a ligand-activated nuclear transcription factor, the estrogen receptor (ER), that Correspondence to: J. Balthazart Contract grant sponsor: NIMH; contract grant number: R01 MH50388 Contract grant sponsor: Belgian FRFC; contract grant number: 9.4565.96F Contract grant sponsor: University of Lie `ge Contract grant sponsor: Belgian FNRS; contract grant number: 1.5.081.98 Contract grant sponsor: NATO; contract grant number: CRG 973000 © 1999 John Wiley & Sons, Inc. CCC 0022-3034/99/030327-16 327