Reference : Brain testosterone metabolism during ontogeny in the zebra finch.
Scientific journals : Article
Life sciences : Zoology
Social & behavioral sciences, psychology : Neurosciences & behavior
Brain testosterone metabolism during ontogeny in the zebra finch.
Balthazart, Jacques mailto [> > > >]
Schumacher, M. [> > > >]
Prove, E. [ > > ]
Brain Research
Elsevier Science
Yes (verified by ORBi)
The Netherlands
[en] 3-Oxo-5-alpha-Steroid 4-Dehydrogenase/metabolism ; Age Factors ; Animals ; Birds/metabolism ; Brain/metabolism ; Female ; Kinetics ; Male ; Oxidation-Reduction ; Oxidoreductases/metabolism ; Sex Characteristics ; Testosterone/metabolism ; Vocalization, Animal/physiology
[en] The testosterone metabolism in different parts of the brain and in the syrinx was studied by an in vitro radioenzyme assay in male and female zebra finch (Taeniopygia guttata castanotis) at various ages between 1 day post-hatch and adulthood. The 5 beta-reductase appeared in all experiments as the main enzyme involved in testosterone metabolism. Two experiments allowed to determine the kinetic parameters of the 5 beta-reductase. It was shown that the Vmax of the 5 beta-reduction is much higher in very young animals than in adults but that the Km of the enzyme is smaller (higher affinity) in the latter than in the former. A major decrease of 5 beta-reductase activity is observed during the ontogeny of both males and females in all the tissue samples which were studied including the hypothalamus and brain regions containing nuclei of the song system. This high reductase activity which produces behaviorally inactive compounds is likely to play a protective role during the sexual differentiation of the birds and in this way prevent the masculinization in females of the song system by the relatively high levels of circulating androgens.

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