Phosphorylation processes mediate rapid changes of brain aromatase activity.

Area of Science:

• Neuroendocrinology
• Molecular Endocrinology
• Reproductive Biology

Background:

• Aromatase (estrogen synthase) is crucial for testosterone's reproductive actions.
• Its regulation in the quail brain, particularly the medial preoptic nucleus (POM), is key to male sexual behavior.
• Understanding estrogen's rapid signaling mechanisms in the brain is important.

Purpose of the Study:

• To investigate the distribution and regulation of aromatase in the quail brain.
• To explore the rapid, calcium-dependent regulation of aromatase activity.
• To understand how local estrogen production impacts neuronal physiology.

Main Methods:

• Radioenzyme assays on microdissected brain areas.
• Immunocytochemistry and in situ hybridization.
• RT-PCR.
• Hypothalamic homogenate and explant studies with calcium and kinase modulators.

Main Results:

• High aromatase activity (AA) is localized in the POM, a steroid-sensitive area critical for male sexual behavior.
• AA is rapidly down-regulated by conditions enhancing protein phosphorylation (Ca2+, Mg2+, ATP).
• AA is rapidly and reversibly regulated by high Ca2+ levels in hypothalamic explants, suggesting neurotransmitter influence.

Conclusions:

• Aromatase synthesis and activity in the quail brain are subject to rapid, calcium-dependent regulation.
• Local estrogen production can be quickly modulated by neuronal activity.
• This rapid regulation allows for non-genomic estrogen signaling, similar to neurotransmitters.