Aromatase in the cerebral cortex, hippocampus, and mid-brain: ontogeny and developmental implications

Area of Science:

• Neuroendocrinology
• Developmental Neuroscience
• Biochemistry

Background:

• Estrogen is crucial for brain development and function.
• The presence and role of local estrogen biosynthesis in the brain are not fully understood.
• Aromatase is the key enzyme responsible for estrogen synthesis.

Purpose of the Study:

• To investigate the presence and activity of aromatase in the developing rodent brain.
• To determine the specific brain regions and developmental stages where aromatase activity is detected.
• To explore the potential role of local estrogen biosynthesis in brain sexual differentiation.

Main Methods:

• Explant cultures of newborn mouse and rat brain tissue.
• Homogenates of rat brain regions from birth to 51 days of age.
• Measurement of aromatase activity using radiolabeled androgen substrates.

Main Results:

• Aromatase activity was detected in explants from mouse and rat brain regions including the preoptic area, cingulate cortex, and midbrain.
• Estrogen biosynthesis was not observed in cerebellum or spinal cord explants.
• Aromatase activity was highest in the hypothalamus-preoptic area and amygdala, and significantly higher in early postnatal life, declining in adults.
• Activity was detected in hypothalamus, amygdala, hippocampus, cingulate cortex, and midbrain from birth.

Conclusions:

• Developing rodent brains, particularly neo- and archicortex regions, possess the capacity for local estrogen biosynthesis.
• Aromatase activity is developmentally regulated and region-specific within the brain.
• These findings support a role for local estrogen production in the sexual differentiation of higher brain functions.