Serotonergic cells of the rat raphe nuclei express mRNA of tyrosine kinaseB (trkB), the high-affinity receptor for brain derived neurotrophic factor(BDNF)

Here we have studied the distribution of mRNA for tyrosine kinase B (trkB). the high-affinity receptor for brain-derived neurotrophic factor (BDNF) am ongst serotonergic cell bodies of the raphe nuclei and their ascending proj ections into the dorsal hippocampus in the rat brain. Previous studies have shown that BDNF has got trophic action on serotonergic neurons. In the pre sent study, we provide evidence that serotonergic neurons express mRNA for the functional receptor of BDNF, trkB. Intracerebro-ventricular (i.c.v.) in jection of the 5-HT-specific neurotoxin, 5,7-dihydroxytryptamine, which les ions serotonergic cell bodies in the raphe nuclei as well as their ascendin g projections into the dorsal hippocampus. caused a dramatic loss of trkB m RNA from serotonergic cell bodies of the dorsal raphe nucleus. In contrast. there was no change in the abundance of trkB mRNA within the dorsal hippoc ampus. These findings provide direct evidence for the expression of trkB mR NA by serotonergic neurons and suggest distinct mechanisms of action of BDN F upon serotonergic neurons at the levels of their cell bodies and terminal projection sites. (C) 2001 Elsevier Science B.V. All rights reserved.