DISTRIBUTION OF ANDROGEN RECEPTOR-IMMUNOREACTIVE CELLS IN THE QUAIL FOREBRAIN AND THEIR RELATIONSHIP WITH AROMATASE IMMUNOREACTIVITY

The distribution of androgen receptor-like immunoreactive (AR-ir) cell s in the quail brain was analyzed by immunocytochemistry with the use of the affinity-purified antibody PG-21-19A raised against a synthetic peptide representing the first 21 N-terminal amino acids of the rat a nd human AR. This antibody is known to bind to the receptor in the abs ence as well as in the presence of endogenous ligands, and it was ther efore expected that a more complete and accurate characterization of A R-ir cells would be obtained in comparison with previous studies using an antibody that preferentially recognizes the occupied receptor. Sel ected sections were double labeled for aromatase (ARO) by a technique that uses alkaline phosphatase as the reporter enzyme and Fast blue as the chromogen, AR-ir material was detected in the nucleus of cells lo cated in a variety of brain areas in the preoptic region and the hypot halamus including the medial preoptic (POM), the supraoptic, the parav entricular (PVN), and the ventromedial (VMN) nuclei, but also in the t uberculum olfactorium, the nucleus accumbens/ventral striatum, the nuc leus taeniae, the tuberal hypothalamus, the substantia grisea centrali s (GCt), and the locus ceruleus, Cells exhibiting a dense AR-ir label were also detected in the nucleus intercollicularis, Preincubation of the primary antibody with an excess of the synthetic peptide used for immunization completely eliminated this nuclear staining. A significan t number of AR-ir cells in the POM, VMN, PVN, and tuberal hypothalamus also contained ARO-ir material in their cytoplasm, These data confirm and extend previous studies localizing AR in the avian brain, and rai se questions about the possible regulation by androgens of the metabol izing enzyme aromatase. (C) 1998 John Wiley & Sons, Inc.