Increased expression of estrogen receptor α and β in the nucleus basalis of Meynert in Alzheimer’s disease

The human nucleus basalis of Meynert (NBM) is severely affected in Alzheimer’s disease (AD). Since estrogens may reduce both the risk and severity of AD, possibly by an action on the cholinergic system, we determined whether estrogen receptors are present in the human NBM and what their changes are in normal aging and in AD. ERα was expressed to a higher degree than ERβ and was localized mainly in the cell nucleus, while ERβ was mainly confined to the cytoplasm. A significant positive correlation between the percentage of ERα nuclear positive neurons and age was found in men but not in women, whereas the proportion of ERβ cytoplasm positive cells increased during aging in both sexes. In AD the proportion of neurons showing nuclear staining for both ERα and β and cytoplasmic staining for ERβ was markedly increased. The percentage of ERβ nuclear positive neurons increased in AD only in women but not in men. The ApoE genotype had no effect on ER expression in the NBM in AD. In conclusion, whereas only minor sex- and age-related changes in both ERs were found in the human NBM, a clear upregulation of ERα and β was observed in AD.