Cloning and Expression of Zebra Finch (Taeniopygia guttata) Steroidogenic Factor 1: Overlap with Hypothalamic but Not with Telencephalic Aromatase

• Published in: Biology of reproduction Vol. 66; no. 4; pp. 1127 - 1133
• Main Authors: AGATE, Robert J, PERLMAN, William R, ARNOLD, Arthur P
• Format: Journal Article
• Language: English
• Published: Madison, WI Society for the Study of Reproduction 01-04-2002
• Subjects: Adrenal Glands - chemistry; Amino Acid Sequence; Animals; Aromatase - genetics; Base Sequence; Biological and medical sciences; Blotting, Northern; Cloning, Molecular; DNA, Complementary - chemistry; DNA, Complementary - isolation & purification; DNA-Binding Proteins - chemistry; DNA-Binding Proteins - genetics; Female; Fushi Tarazu Transcription Factors; Gene Expression; Homeodomain Proteins; Hypothalamus - chemistry; In Situ Hybridization; Male; Molecular Sequence Data; Ovary - chemistry; Receptors, Cytoplasmic and Nuclear; Reverse Transcriptase Polymerase Chain Reaction; Songbirds - genetics; Steroidogenic Factor 1; Telencephalon - chemistry; Testis - chemistry; Transcription Factors - chemistry; Transcription Factors - genetics
• ISSN: 0006-3363; 1529-7268
• DOI: 10.1095/biolreprod66.4.1127

The zebra finch ( Taeniopygia guttata ) brain is highly sexually dimorphic. The organization and production of sex-specific song is considerably influenced by estrogens
and androgens. Because the brain itself expresses several steroidogenic enzymes, the local production of sex steroids may
contribute to sex differences in neural development. Sex steroid production in gonads is directed by a master regulatory factor,
steroidogenic factor 1 (SF1). We have identified a cDNA encoding the homologue of SF1 in the zebra finch and utilized reverse
transcription-polymerase chain reaction and in situ hybridization to examine early and late developmental expression of SF1
in brain and in early gonadal development. We found that SF1 is expressed early in embryonic development in the Rathke pouch,
beginning at stage 15 and extending to at least stage 27 in both males and females. The earliest expression of SF1 in gonads
was found at stage 17 for both males and females and extended to at least stage 27. In brain, we assessed SF1 mRNA expression
in posthatch and adult telencephalon, and we compared SF1 and aromatase mRNA expression in adult hypothalamus. In the telencephalon
and hippocampus, aromatase was expressed independently of SF1, whereas in the hypothalamus, aromatase and SF1 expression were
more closely associated. Expression of SF1 and of aromatase overlapped in restricted regions of the hypothalamus, suggesting
that SF1 may regulate aromatase expression in these regions. These findings suggest that steroidogenesis in the zebra finch
brain may be regulated by both SF1-dependent and SF1-independent mechanisms. No sex differences were detected in SF1 expression
in brain.