title: Sex differences in the distribution of the steroid receptor coactivator SRC-1 in the song control nuclei of male and female canaries.
abstract: The steroid receptor coactivator SRC-1 modulates ligand-dependent transactivation of several nuclear receptors, including the receptors for sex steroid hormones. The distribution of SRC-1 transcripts was analyzed here by in situ hybridization in coronal sections through the brain of male and female canaries. A broad but heterogeneous distribution of SRC-1 transcripts was observed with high numbers of densely labeled cells being present in many steroid-sensitive areas including the medial preoptic nucleus, several hypothalamic nuclei, five song control nuclei (HVc, the lateral and medial portion of the magnocellular nucleus of the anterior neostriatum, area X and the nucleus uvaeformis) and several catecholaminergic areas (area ventralis of Tsai, substantia nigra, locus coeruleus). The volume of two song control nuclei, HVc and area X were reconstructed based on the boundaries of the cell groups exhibiting a denser SRC-1 expression as compared to the surrounding areas. Sex differences in the expression of SRC-1 were also detected in several song control nuclei. In particular, the volume of HVc based on the high density of SRC-1 expression was significantly larger in males than in females. The effect of steroids on the song control system could be, at least in part, indirect and result from a modulation by steroids of the catecholaminergic inputs to the song control nuclei. The presence of the steroid receptor coactivator SRC-1 in the telencephalic song control nuclei and in the catecholaminergic cell groups that innervate the song system supports the idea that SRC-1 expression could play an active role in the control of singing behavior by modulating estrogen and androgen receptor action at both locations.
authors.affiliation: Center for Cellular and Molecular Neurobiology, Research Group in Behavioral Neuroendocrinology, University of Liège, 17 Place Delcour (Bat. L1), B-4020, Liège, Belgium.
authors.forename: Thierry D
authors.initials: TD
authors.lastname: Charlier
authors.forename: Jacques
authors.initials: J
authors.lastname: Balthazart
authors.forename: Gregory F
authors.initials: GF
authors.lastname: Ball
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism*; D002171:Canaries / Q000378:metabolism*; D005260:Female; D051548:Histone Acetyltransferases; D008297:Male; D056920:Nuclear Receptor Coactivator 1; D012727:Sex Characteristics; D014157:Transcription Factors / Q000032:analysis / Q000096:biosynthesis*; D014828:Vocalization, Animal / Q000502:physiology*
chemical_list: D014157:Transcription Factors; D051548:Histone Acetyltransferases; D056920:Nuclear Receptor Coactivator 1