Differential age-dependent trophic responses of nodose, sensory, and sympathetic neurons to neurotrophins and GDNF: potencies for neurite extension in explant culture.

Abstract

The age-dependent trophic responses of sympathetic, sensory, and nodose neurons to the neurotrophins NGF, BDNF, and NT-3 and to glial cell line-derived neurotrophic factor (GDNF) were examined by an explant culture system. Superior cervical ganglia (SCG), dorsal root ganglia (DRG), and nodose ganglia (NG) were removed from rat embryos (E18), neonatals (< or = 1 day old), young adults (3-6 months old), and aged adults (> 24 months old). The ganglia were cultured with and without each neurotrophic factor; the neurite extension and neurite density were then assessed. The SCG from rats of all ages were significantly influenced by NGF, NT-3, and GDNF; the effects of NT-3 and GDNF were reduced after maturation. The DRG from embryos and neonates were influenced by all neurotrophic factors; however, the effects of BDNF and NT-3 disappeared after maturation. The GDNF showed little effect on adult DRG and no effect on aged DRG. The effect of NGF was preserved over all ages of DRG. The NG from embryonic rats were significantly responsive to BDNF and GDNF; their effects decreased in the neonatal NG, but a minimum effect remained in the aged NG. These results indicate that age-dependent profiles of trophic effects differ extensively among the lineages of the peripheral nervous system and also among the individual neurotrophic factors.