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Developmental sex differences in brain aromatase activity are related to androgen level.

Authors
Type
Published Article
Journal
Developmental Brain Research
0165-3806
Publisher
Elsevier
Publication Date
Volume
57
Issue
2
Pages
187–195
Identifiers
PMID: 2073719
Source
Medline
License
Unknown

Abstract

Sex differences in the metabolism of testosterone (T) in the developing brain of quail were examined using an in vitro microassay. During each developmental stage (day before hatching, hatching and 2 days after hatching) aromatase activity was higher in hypothalamic areas than in a control neostriatal area. There was no sex difference in oestradiol-17 beta (E2) formation in the late embryonic brain or at hatching. But aromatase activity in the male preoptic-anterior hypothalamic area was 50% higher than in females by day 2. No regional differences in brain 5 beta-reductase activity were detected at any of the developmental stages sampled. There was a sex difference in production of catabolic 5 beta-reduced metabolites. Male 5 beta-reductase activity declined continuously from high embryonic levels in all areas, whereas female enzyme activity showed an increase at hatching. In contrast to plasma progesterone, levels of T were higher in the male than in the female by day 1 after hatching. We suggest that elevated circulating T in the male after hatching may account for the sexual dimorphism in brain aromatase activity.

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