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Cloning of the zebra finch androgen synthetic enzyme CYP17: A study of its neural expression throughout posthatch development
Author(s) -
London Sarah E.,
Boulter Jim,
Schlinger Barney A.
Publication year - 2003
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.10936
Subject(s) - zebra finch , aromatase , biology , neuroactive steroid , songbird , in situ hybridization , androgen , cloning (programming) , sexual differentiation , estrogen , medicine , endocrinology , neural substrate , neuroscience , messenger rna , genetics , gene , hormone , receptor , gabaa receptor , paleontology , cognition , cancer , breast cancer , computer science , programming language
Male zebra finches develop a robust neural song system that supports singing, but females have a minimal song circuit and do not sing. Estrogens masculinize the song circuit and are especially potent during the first 3 weeks of posthatch development. The gonads do not seem to supply the masculinizing steroids, implying that another tissue synthesizes steroids. Evidence suggests that the brain is capable of synthesizing neurosteroids, which in developing zebra finches may be required for song system differentiation. Aromatase, the enzyme that synthesizes estrogen from androgen, is equally abundant in male and female brains. To investigate further the potential for neurosteroidogenesis in the zebra finch brain, we cloned and examined the expression of 17α‐hydroxylase/17,20 lyase (CYP17), the enzyme that synthesizes the androgenic substrate for aromatase. We used Northern blots, reverse transcription‐polymerase chain reaction, and in situ hybridization to show that CYP17 is transcribed in developing and adult brains. CYP17 is transcribed at developmental stages and in brain areas potentially important to aspects of the developing song system, although no sex difference was detected in mRNA levels. Our results support the hypothesis that neurosteroids may act to influence brain organization and function in the zebra finch. J. Comp. Neurol. 467:496–508, 2003. © 2003 Wiley‐Liss, Inc.