• [Show abstract] [Hide abstract]     ABSTRACT: Insulin-like
growth factor-1 (IGF-1) is a neurotrophic factor expressed in
small dorsal root ganglion (DRG) neurons. IGF-1 promotes
neuronal survival by activating its receptor (IGF-1R). Whether
IGF-1 and its signaling pathways influence the expression of
tyrosine kinase receptors TrkA, TrkB and TrkC in DRG neurons
remains unknown. In the present study, primary cultured DRG
neurons were used to determine the effects of IGF-1 on TrkA,
TrkB and TrkC expression. The involvement of extracellular
signal-regulated protein kinase (ERK1/2) and the effects of
phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathways on
IGF-1 were also evaluated. DRG neurons were cultured for 48h and
then exposed to IGF-1, PD98059 plus IGF-1, LY294002 plus IGF-1,
and PD98059 plus LY294002 plus IGF-1 for an additional 24h. The
DRG neurons were continuously exposed to culture medium as a
control. All cultures were then processed for detection of mRNA
levels of TrkA, TrkB and TrkC using re