Isolation and characterization of a zebra finch aromatase cDNA: in situ hybridization reveals high aromatase expression in brain

doi:10.1016/0169-328X(94)90136-8

Molecular Brain Research

Volume 24, Issues 1–4, July 1994, Pages 227-237

https://doi.org/10.1016/0169-328X(94)90136-8 Get rights and content

Abstract

The brain regions controlling song are much larger in male than in female zebra finches. This sex difference is thought to arise developmentally when the male's brain is exposed to higher levels of estrogen. The synthesis of estrogen from androgen is catalyzed by aromatase, a key enzyme implicated in song development in the zebra finch. To study the role of estrogen synthesis in the organization of brain regions responsible for song, a cDNA encoding aromatase was isolated from a zebra finch ovarian cDNA library. The 3188 bp cDNA contains a 1527 bp open reading frame with 5′ and 3′ untranslated regions of 116 bp and 1545 bp, respectively. The deduced polypeptide is 509 amino acids in length, and is highly homologous to aromatases reported for chicken (92%), human (72%), mouse (70%), rat (69%) and trout (53%). Northern blot analysis revealed 5.4 kb, 4.8 kb and 3.2 kb aromatase mRNAs in brain and ovary. In situ hybridization histochemistry revealed the expression of aromatase mRNA in ovarian thecal cells of some, but not all, follicles, suggesting that aromatase gene expression is regulated during follicular maturation. In the adult brain, the distribution of aromatase mRNA was surprisingly widespread, and included the preoptic area, hypothalamus, hippocampus and neostriatum. By contrast, little aromatase mRNA expression was noted in the song nuclei (HVC, RA, area X). This study, the first description of aromatase mRNA expression by in situ hybridization in the brain of any species, identifies a surprisingly large number of cells that express aromatase mRNA in the zebra finch telencephalon. This pattern may be a unique feature of all songbirds.

Reference (72)

Adkins-ReganE. et al.
Sexual differentiation of behavior in the zebra finch: effect of early gonadectomy or androgen treatment
Horm. Behav.
(1990)
Adkins-ReganE. et al.
Sex steroid levels in developing and adult male and female zebra finches (Poephila guttata)
Gen. Comp. Endocrinol.
(1990)
BalthazartJ. et al.
Behavioral demasculinization of female quail is induced by estrogens: studies with the new aromatase inhibitor, R76713
Horm. Behav.
(1992)
ChenS. et al.
Functional domains of aromatase cytochrome P450 inferred from comparative analyses of amino acid sequences and substantiated by site-directed mutagenesis experiments
J. Biol. Chem.
(1992)
ChomczynskiP. et al.
Single-step method of RNA isolation by acid guanidinium thiocyanate-phenol-chloroform extraction
Anal. Biochem.
(1987)
FeinbergA.P. et al.
A technique for radiolabeling DNA restriction endonuclease fragments to high specific activity
Anal. Biochem.
(1983)
GahrM. et al.
Immunocytochemical localization of estrogen-binding neurons in the songbird brain
Brain Res.
(1987)
Graham-LorenceS. et al.
Structure-function relationships of human cytochrome P-450 using molecular modeling and site-directed mutagenesis
J. Biol. Chem.
(1991)
HaradaN.
Cloning of a complete cDNA encoding human aromatase: immunochemical identification and sequence analysis
Biochem. Biophys. Res. Commun.
(1988)
KroodsmaD.E.
Song development by castrated marsh wrens
Anim. Behav.
(1986)

LephartE.D. et al.

The structure of cDNA clones encoding the aromatase P-450 isolated from a rat Leydig cell tumor line demonstrates differential processing of aromatase mRNA in rat ovary and a neoplastic cell line

Mol. Cell. Endocrinol.

(1990)

McPhaulM.J. et al.

The expression of a functional cDNA encoding the chicken cytochrome P-450_arom (aromatase) that catalyzes the formation of estrogen from androgen

J. Biol. Chem.

(1988)

Negri-CesiP. et al.

Androgen metabolism in the male hamster — 2. Aromatization of androstenedione in the hypothalamus and in the cerebral cortex; kinetic parameters and effect of exposure to different photoperiods

J. Steroid. Biochem.

(1989)

RyanK.J. et al.

Estrogen formation in the brain

Am. J. Obstet. Gynecol.

(1972)

SouthernE.M.

Detection of specific sequences among DNA fragments separated by gel electrophoresis

J. Mol. Biol.

(1975)

TerashimaM. et al.

Isolation of a full-length cDNA encoding mouse aromatase P450

Arch. Biochem. Biophys.

(1991)

TodaK. et al.

Alternative usage of different poly(A) addition signals for two major species of mRNA encoding human aromatase P-450

FEBS Lett.

(1989)

VockelA. et al.

Sex- and age-related differences in the activity of testosterone-metabolizing enzymes in microdissected nuclei of the zebra finch brain

Brain Res.

(1990)

ZhouD. et al.

A site-directed mutagenesis study of human placental aromatase

J. Biol. Chem.

(1992)

ArnoldA.P.

The effects of castration on song development in zebra finches (Poephila guttata)

J. Exp. Zool.

(1975)

AvivH. et al.

Purification of biologically active globin messenger RNA by chromatography on oligothymidylic acid-cellulose

BalthazartJ. et al.

Distribution of aromatase in the brain of the Japanese quail, ring dove, and zebra finch: an immunocytochemical study

J. Comp. Neurol.

(1990)

CallardG.V. et al.

Phylogenetic distribution of aromatase and other androgen-converting enzymes in the central nervous system

Endocrinology

(1978)

CorbinC.J. et al.

Isolation of a full-length cDNA insert encoding human aromatase system cytochrome P-450 and its expression in nonsteroidogenic cells

Do¨hlerK.D. et al.

Pre- and postnatal influence of an estrogen antagonist and an androgen antagonist on differentiation of the sexually dimorphic nucleus of the preoptic area in male and female rats

Neuroendocrinology

(1986)

ElbrechtA. et al.

Aromatase enzyme activity and sex determination in chickens

Science

(1992)

GahrM. et al.

Estrogen receptors in the avian brain: survey reveals general distribution and forebrain areas unique to songbirds

J. Comp. Neurol.

(1993)

GeorgeF.W. et al.

Aromatase activity in the developing rabbit brain

Endocrinology

(1978)

GonzalezF.J.

The molecular biology of cytochrome P450s

Pharmacol. Rev.

(1989)

GurneyM.E. et al.

Hormone-induced sexual differentiation of brain and behavior in zebra finches

Science

(1980)

GurneyM.E.

Hormonal control of cell form and number in the zebra finch song system

J. Neurosci.

(1981)

HickeyG.J. et al.

Aromatase cytochrome P450 in rat ovarian granulosa cells before and after luteinization: adenosine 3′,5′-monophosphate-dependent and independent regulation

HuangE.S. et al.

Synthesis of sex steroids by cellular components of chicken follicles

Biol. Reprod.

(1979)

HutchisonJ.B. et al.

Sex differences in plasma concentrations of steroids during the sensitive period for brain differentiation in the zebra finch

J. Endocrinol.

(1984)

KelleyD.B. et al.

Projections of a telencephalic auditory nucleus — Field L — in the canary

J. Comp. Neurol.

(1979)

MacLuskyN.J. et al.

Sexual differentiation of the central nervous system

Science

(1981)

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Isolation and characterization of a zebra finch aromatase cDNA: in situ hybridization reveals high aromatase expression in brain

Abstract

Horm. Behav.

Gen. Comp. Endocrinol.

Horm. Behav.

J. Biol. Chem.

Anal. Biochem.

Anal. Biochem.

Brain Res.

J. Biol. Chem.

Biochem. Biophys. Res. Commun.

Anim. Behav.

Mol. Cell. Endocrinol.

J. Biol. Chem.

J. Steroid. Biochem.

Am. J. Obstet. Gynecol.

J. Mol. Biol.

Arch. Biochem. Biophys.

FEBS Lett.

Brain Res.

J. Biol. Chem.

The effects of castration on song development in zebra finches (Poephila guttata)

J. Exp. Zool.

Purification of biologically active globin messenger RNA by chromatography on oligothymidylic acid-cellulose

Distribution of aromatase in the brain of the Japanese quail, ring dove, and zebra finch: an immunocytochemical study

J. Comp. Neurol.

Phylogenetic distribution of aromatase and other androgen-converting enzymes in the central nervous system

Endocrinology

Isolation of a full-length cDNA insert encoding human aromatase system cytochrome P-450 and its expression in nonsteroidogenic cells

Pre- and postnatal influence of an estrogen antagonist and an androgen antagonist on differentiation of the sexually dimorphic nucleus of the preoptic area in male and female rats

Neuroendocrinology

Aromatase enzyme activity and sex determination in chickens

Science

Estrogen receptors in the avian brain: survey reveals general distribution and forebrain areas unique to songbirds

J. Comp. Neurol.

Aromatase activity in the developing rabbit brain

Endocrinology

The molecular biology of cytochrome P450s

Pharmacol. Rev.

Hormone-induced sexual differentiation of brain and behavior in zebra finches

Science

Hormonal control of cell form and number in the zebra finch song system

J. Neurosci.

Aromatase cytochrome P450 in rat ovarian granulosa cells before and after luteinization: adenosine 3′,5′-monophosphate-dependent and independent regulation

Synthesis of sex steroids by cellular components of chicken follicles

Biol. Reprod.

Sex differences in plasma concentrations of steroids during the sensitive period for brain differentiation in the zebra finch

J. Endocrinol.

Projections of a telencephalic auditory nucleus — Field L — in the canary

J. Comp. Neurol.

Sexual differentiation of the central nervous system

Science