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3beta-HSD activates DHEA in the songbird brain
Barney A Schlinger1, Devaleena S Pradhan, Kiran K Soma
1Department of Physiological Science, Laboratory of Neuroendocrinology of the Brain Research Institute, UCLA, Los Angeles, CA 90095, USA. schling@lifesci.ucla.edu
Neurochemistry International
|July 24, 2007
Summary
Dehydroepiandrosterone (DHEA) is a key prohormone in songbirds, with its conversion enzyme, 3beta-hydroxysteroid dehydrogenase/isomerase (3beta-HSD), highly active in the brain. This highlights DHEA's role in songbird behavior and neuroplasticity.
Area of Science:
- Neuroendocrinology
- Avian Biology
- Steroid Biochemistry
Background:
- Dehydroepiandrosterone (DHEA) is an abundant human prohormone, but its functions remain unclear due to low levels in common lab animals.
- Avian studies reveal DHEA is a significant circulating prohormone in songbirds.
- The enzyme 3beta-hydroxysteroid dehydrogenase/isomerase (3beta-HSD) is highly expressed in the songbird brain, converting DHEA to active androgens.
Purpose of the Study:
- To review evidence on the activity and expression of 3beta-HSD in the songbird brain.
- To examine seasonal and stress-related changes in circulating DHEA levels in songbirds.
- To explore the role of DHEA in song behavior and neural circuit development.
Main Methods:
- Biochemical and molecular studies of 3beta-HSD activity and expression in the songbird brain.
- Analysis of circulating DHEA levels in captive and wild songbird species under various conditions.
- Behavioral and neurobiological assessments following DHEA administration.
Main Results:
- Neural 3beta-HSD activity is widespread in the songbird brain, with region-specific responses to sex, stress, and season.
- Circulating DHEA levels exhibit seasonal and stress-dependent variations in songbirds.
- DHEA treatment enhances song behavior and promotes the growth of song-controlling neural circuits.
- Brain 3beta-HSD and aromatase collaborate to locally produce androgens and estrogens from DHEA, crucial for behavior and neuroplasticity.
Conclusions:
- DHEA is a vital prohormone in songbirds, metabolized in the brain by 3beta-HSD and aromatase to regulate behavior and neuroplasticity.
- 3beta-HSD is a critical enzyme in the songbird brain, mediating DHEA's effects.
- DHEA may be synthesized in the songbird brain or sourced from gonads/adrenals, similar to humans.
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