High affinity neurotrophin receptors in cholinergic neurons in the human brain.

Tyrosine protein kinases TrkA and TrkC are signal-transducing receptors for nerve growth factor (NGF) and neurotrophin-3 (NT-3), respectively. In the human brain postmortem, using sequential immunohistochemistry, we detected the presence of TrkA and TrkC on 99% and 95% of cholinergic neurons from the basal forebrain and on some cholinergic neurons (22% and 16%, respectively) from the striatum, but not on those from the mesencephalon. These results suggest that some cholinergic neurons, particularly those of the nucleus basalis of Meynert, may be sensitive to both NGF and NT-3 in the human brain. The sensitivity of cholinergic neurons to these two neurotrophins may have a special interest in therapeutic strategies for Alzheimer's disease.