Abstract
1. In situ hybridization histochemistry was used to localize nerve growth factor receptor (NGFR) mRNA in the adult rat basal forebrain. 2. In emulsion-dipped sections 35S-labeled RNA antisense probes produced a high density of silver grains over cells located in the medial septum, vertical and horizontal limbs of the diagonal band of Broca, and nucleus basalis. 3. This distribution of NGFR mRNA overlaps with the distribution of NGFR protein localized using immunocytochemical techniques. 4. No hybridization signal was detected when sections were hybridized with a 35S-labeled RNA sense (control) probe. 5. We suggest that NGFRs are synthesized in these basal forebrain nuclei and transported to terminal areas where NGF is thought to be bound and internalized, an initial step in the many actions of this neurotrophic factor.