From the article:
Brann and his colleagues found that mice whose neurons don’t make estrogen have impaired spatial reference memory – like a baseball player not knowing where home plate is and what it means to get there – as well as recognition memory and contextual fear memory – so they have trouble remembering what’s hazardous – they report in the Journal of Neuroscience.
Restoring estrogen levels to the brain area rescues these impaired functions, Brann and his colleagues report.
It was known that aromatase, the enzyme that converts testosterone to estrogen, was made in the brain’s hippocampus and cerebral cortex in a variety of species that includes humans, Brann says, and that they all can have memory deficits when aromatase is blocked. Patients who take an aromatase inhibitor for estrogen-dependent breast cancer also have reported memory problems.
Knocking out aromatase also decreased expression of CREB, a major transcription factor known to play a key role in learning and memory, the scientists write, as well as neuron-nourishing brain derived neurotrophic factor, or BDNF.
The scientists say these findings implicate neuron-derived estrogen as a novel neuromodulator, basically a critical messenger one neuron relies on to communicate with others, which is essential to key functions like cognition.