Expression of catalytic trkB gene in the striatum and the basal forebrain of patients with Alzheimer's disease: An in situ hybridization study

The expression of catalytic trkB gene, encoding for the high affinity brain-derived neurotrophic factor (BDNF) and neurotrophin-4/5 (NT-4/5) receptor, was studied post mortem in the striatum and the nucleus basalis of Meynert of patients with Alzheimer's disease (AD) and control subjects, using in situ hybridization coupled with choline acetyltransferase immunohistochemistry. Microscopic examination of tissue sections showed labelling on perikarya of neurons but no labelling on glial cells. In the striatum, cholinergic as well as non-cholinergic and, presumably GABAergic, neurons expressed detectable levels of TrkB mRNA, while in the nucleus basalis of Meynert, only cholinergic neurons were labelled. Quantitative analysis of the in situ hybridization signal in cells of these two regions failed to demonstrate any significant difference between AD patients and control subjects. Normal levels of TrkB mRNA in the surviving cholinergic neurons of the nucleus basalis of Meynert suggest that these neurons could respond to an exogenous supply of BDNF and/or NT-4/5. (C) 1997 Elsevier Science Ireland Ltd.