Alterations in TrkA, TrkB and TrkC receptor immunoreactivities in parietalcortex and cerebellum in Alzheimer's disease

The neurotrophins nerve growth factor, brain-derived neurotrophic factor an d neurotrophin-3 bind to the tyrosine kinase (trk) receptors trk A, trk B a nd trk C, respectively, with high affinity. We investigated the expression of the trk receptors in the parietal cortex (PC) and cerebellum of patients with Alzheimer's disease (AD) and age-matched controls. Cortical layers II -VI displayed a distinct cellular immunoreactivity for trk A and C with an emphasis in the pyramidal neurons of layers III and V. Trk B immunoreactivi ty was primarily located in the deeper cortical layers with a predominance in layer V. There was a decrease in trk A and C immunoreactivity in the PC of AD cases, while trk B density appeared to be unchanged. In addition, cer ebellar Purkinje cells revealed a distinct immunoreactivity for trk C both in control and AD cases, suggesting trk C may be important in the maintenan ce of these cells in the aged brain. Copyright (C) 2000 S. Karger AG, Basel .