Neurotrophin receptor expression and responsiveness by postnatal cerebral oligodendroglia

The low affinity neurotrophin receptor (p75) is implicated in promoting oligodendrocytic death after nerve growth factor (NGF) stimulation but NGF and neurotrophin-3 (NT-3) can also potentiate oligodendrocytic survival. We show regional variability in p75 expression within the central nervous system of the postnatal rat; expression is readily detectable by immunohistochemistry upon a subset of CNPase-positive oligodendroglia in optic nerve but not within the cerebrum. Nevertheless, oligodendroglia isolated from the cerebrum and cultured for 16 hours express p75 as well as the trkC but not the TrkA gene. Viability was not, however, influenced by exposure to either NGF or NT-3. Cells overexpressing p75 remained unresponsive to NGF but exhibited potentiated survival with NT-3, correlating with the differential expression profile of their high affinity receptors.