COEXPRESSION OF TRKB AND TRKC RECEPTORS IN CNS NEURONS SUGGESTS REGULATION BY MULTIPLE NEUROTROPHINS

USING double-label in situ hybridization, we have explored the possibi lity that individual CNS neurones can co-express mRNAs for the high-af finity receptors of brain-derived neurotrophic factor and neurotrophin -3, TrkB and TrkC, respectively. The vast majority of TrkC mRNA-contai ning neurones in the hippocampal formation and cerebral cortex were al so labelled for TrkB mRNA. Cells expressing only TrkB or TrkC mRNA wer e very scarce in these regions, representing < 15% of all labelled cel ls. These findings suggest that the same cortical or hippocampal neuro ne can be regulated by several members of the neurotrophin family, whi ch may be important both during development and in response to physiol ogical activity and pathological conditions.