Steroid receptors in the adult zebra finch syrinx: a sex difference in androgen receptor mRNA, minimal expression of estrogen receptor α and aromatase

The zebra finch syrinx (sound production organ) is a sexually dimorphic component of the song system. Only male zebra finches sing, and in parallel, the overall mass and size of fibers in the two largest syrinx muscles are greater in males than females. Despite these obvious sexual dimorphisms, litt...

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Bibliographic Details
Published in:General and comparative endocrinology 2004-04, Vol.136 (2), p.192-199
Main Authors: Veney, Sean L., Wade, Juli
Format: Article
Language:English
Subjects:
Animals
Aromatase - genetics
Aromatase assay
Estrogen Receptor alpha
Female
Gene Expression
In Situ Hybridization
Male
Ovary - chemistry
Oviducts - chemistry
Receptors, Androgen - genetics
Receptors, Estrogen - genetics
RNA, Messenger - analysis
Sex Characteristics
Singing behavior
Songbird
Songbirds - metabolism
Steroid hormones
Taeniopygia guttata
Trachea - chemistry
Vocalization, Animal
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Summary:The zebra finch syrinx (sound production organ) is a sexually dimorphic component of the song system. Only male zebra finches sing, and in parallel, the overall mass and size of fibers in the two largest syrinx muscles are greater in males than females. Despite these obvious sexual dimorphisms, little is known about the role of steroid hormones in the maintenance of the structure and/or function of the syrinx. In this report, we used in situ hybridization to assess the expression of androgen receptor (AR), estrogen receptor α (ERα), and aromatase (AROM) mRNAs in the syrinx of adult male and female zebra finches. Increased AR mRNA expression was noted in males compared to females in two regions, over the ventralis muscle and in a band of connective tissue neighboring cartilage (perichondria). In contrast, we did not detect specific ERα or AROM mRNA expression within the syrinx. However, substantial ERα mRNA was present in oviduct, and aromatase mRNA was expressed at high levels in ovary. In parallel, an assay for AROM detected activity in ovary, but not in syrinx tissue from males or females. Taken together, these data suggest that the adult syrinx is sensitive to androgens; that sex differences in function and morphology of the syrinx may in part be due to increased expression of AR in males compared to females. In contrast, estrogen receptor α and AROM appear to have limited roles.
ISSN:0016-6480
1095-6840
DOI:10.1016/j.ygcen.2003.12.017