The effects of neuregulin-1β on neuronal phenotypes of primary cultured dorsal root ganglion neurons by activation of PI3K/Akt

Neuregulin-1β (NRG-1β) signaling has multiple functions in neurons. NRG-1 signaling regulates neuronal development, migration, myelination, and synaptic maintenance. The neuropeptide- and neurofilament (NF)-immunoreactive (IR) neurons are two major phenotypical classes in dorsal root ganglion (DRG). Whether NRG-1β influences DRG neuronal phenotypes remains unknown. To assess the effects of NRG-1β on DRG neuronal phenotypes, dissociated embryonic rat DRG neuronal culture model was established. Primary cultured DRG neurons were exposed to NRG-1β (5 nmol/L), NRG-1β (10 nmol/L), NRG-1β (20 nmol/L), NRG-1β (20 nmol/L) plus LY294002 (10 μmol/L) for 3 days, respectively. The DRG neurons were continuously exposed to growth media as control. After that, all above cultured DRG neurons were processed for double fluorescent labeling of calcitonin gene-related peptide (CGRP) or neurofilament-200 (NF-200) and microtubule associated protein 2 (MAP2). The percentage of CGRP-IR neurons and NF-200-IR neurons was counted. The expression of CGRP mRNA and NF-200 mRNA was analyzed by real time-PCR analysis. The percentage of CGRP-IR neurons but not NF-200-IR neurons increased significantly in the presence of NRG-1β as compared with that in the absence of NRG-1β. The levels of CGRP mRNA but not NF-200 mRNA increased significantly in the presence of NRG-1β as compared with that in the absence of NRG-1β. PI3K inhibitor LY294002 blocked the effects of NRG-1β. These results support an important role for exogenous NRG-1β in induction of the distinct neuronal phenotype response by activation of PI3K/Akt in sensory neurons.

► Dissociated embryonic rat DRG neuronal culture model was established.
► The effects of NRG-1β on DRG neuronal phenotypes was investigated.
► NRG-1β increased CGRP-IR neurons but not NF-200-IR neurons.
► NRG-1β also increased CGRP mRNA but not NF-200 mRNA.