By contrast, in the two models of chronic neurodegeneration in which brain aromatase has been examined — hyperten¬sion61 and sciatic nerve chronic constriction injury60 — the expression of the enzyme is enhanced in neurons and not in astrocytes. However, aromatase expression is increased in astrocytes in the human prefrontal cor¬tex in the late stages of Alzheimer’s disease29. Thus, at least in some cases, aromatase expression is induced in astrocytes under chronic neurodegenerative conditions. The factors that induce the expression of aromatase in neurons and astrocytes after brain injury remain to be identified125.