Differential regulation of p75 and trkB mRNA expression after depolarizingstimuli or BDNF treatment in basal forebrain neuron cultures

Extensive evidence suggests that BDNF regulates neural function and archite cture after depolarization. Expression of BDNF is increased after depolariz ation, and the ability of BDNF to modulate synaptic function is well docume nted. To further investigate BDNF signaling after activity, we analyzed the effects of depolarization or BDNF treatment on receptor mRNA expression in cultured basal forebrain neurons. Levels of mRNA coding for the cognate BD NF receptor, trkB, as well as the common neurotrophin receptor, p75, were q uantitated simultaneously using a sensitive solution hybridization techniqu e. Depolarization or BDNF treatment increased p75 mRNA expression 94% and 1 95%, respectively. In contrast, trkB message decreased 23% after depolariza tion but was unchanged by BDNF treatment. Together, these changes resulted in significant increases in the p75/trkB ratio after depolarization or BDNF treatment that could alter BDNF binding or signal transduction. (C) 2001 W iley-Liss, Inc.