[A review of brain aromatase].

Aromatase catalyzes the conversion of androgen to estrogen. This enzyme has been primarily localized in the neurons of specific areas of limbic system and hypothalamus of the brain. Astrocytes may also express this enzyme. Studies show that the gene expression of aromatase is driven by multiple tissue-specific exons, and the effective concentration of brain estrogen depends on the expression of brain aromatase. The locally produced estrogen plays an important role in the regulation of synaptogenesis, density of dendritic spine and the expression of neurotrophic factors and/or their receptors. Estrogen can also protect brain cells from the damages of neurotoxins and can greatly improve the deficits of learning and memory resulted from neurodegenerative disorders such as Alzheimer's diseases.