Acute and Specific Modulation of Presynaptic Aromatization in the Vertebrate Brain

Estrogens affect a diversity of peripheral and central physiological endpoints. Traditionally,
estrogens were thought to be peripherally derived transcription regulators (i.e. slow acting).
More recently, we have learned that estrogens are also synthesized in neuronal cell bodies and
synaptic terminals and have potent membrane effects, which modulate brain function. However,
the mechanisms that control local steroid concentrations in a temporal and spatial resolution
compatible with their acute actions are poorly understood. Here, using differential
centrifugation followed by enzymatic assay, we provide evidence that estrogen synthesis
within synaptosomes can be modulated more dramatically by phosphorylating conditions,
relative to microsomes. This is the first demonstration of a rapid mechanism that may alter
steroid concentrations within the synapse and may represent a potential mechanism for the
acute control of neurophysiology and behavior.