COEXPRESSION OF NEUROTROPHINS AND THEIR RECEPTORS IN NEURONS OF THE CENTRAL-NERVOUS-SYSTEM

Nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) are neuronal survival molecules which utilize the Trk family of tyros ine kinase receptors. Using double-label in situ hybridization, we dem onstrate that mRNAs for BDNF and its high-affinity receptor TrkB are c oexpressed in hippocampal and cortical neurons. Also, a large number o f neurons in these areas coexpress NGF and BDNF mRNAs. Epileptic seizu res lead to increased levels of both BDNF/TrkB and NGF/BDNF mRNAs in d ouble-labeled cells. Our results show that individual neurons of the c entral nervous system can coexpress neurotrophins and their receptors and produce two neurotrophic factors. These factors could support neur onal survival after brain insults, not only via retrograde transport b ut also through autocrine mechanisms.