Cholinergic Neurons of the Nucleus basalis Express Elevated Levels of Nerve Growth Factor Receptor mRNA in Senile Dementia of the Alzheimer Type

Magnocellular cholinergic neurons in the nucleus basalis of Meynert (nbM) undergo a profound and selective degeneration in patients with senile dementia of the Alzheimer type (SDAT). We show by in situ hybridization that nerve growth factor (NGF) which promotes the survival of basal-forebrain cholinergic neurons is expressed in hippocampal neurons in SDAT brains at levels not significantly different from those in age-matched controls. In situ hybridization was also used to document the expression of NGF receptor (NGFR) mRNA in magnocellular neurons of the nbM in both SDAT and age-matched control brains. Computerized image analysis of the in situ hybridization results showed that the surviving magnocellular neurons in the nbM of SDAT brains contained 3-fold higher levels of NGFR mRNA compared to age-matched controls. This indicates that in SDAT, the expression of NGFR mRNA is upregulated in magnocellular neurons of the nbM; it further suggests that these neurons respond to exogenously added NGF.