Neurogenesis in postnatal mouse dorsal root ganglia

Neurogenesis continues in various regions of the central nervous system (CN S) throughout life. As the mitogen basic fibroblast growth factor (bFGF) ca n proliferate neuronal precursors of CNS neurons in culture, and is also up regulated within adult dorsal root ganglia following axotomy, it is possibl e that the postnatal dorsal root ganglia contain bFGF-responsive neuronal p recursors. We undertook cell culture of postnatal mouse dorsal root ganglia to demonstrate neurogenesis. Basic FGF induced a cellular proliferative re sponse in dorsal root ganglia cell culture. After 2 weeks in serum-free med ium containing bFGF, neurons were rarely observed. However, following remov al of bFGF and addition of trophic factors, many cells were observed that m orphologically resembled dorsal root ganglia neurons, stained for neuronal markers, and generated action potentials. Furthermore, bromodeoxyuridine, u sed as a marker of cytogenesis, was detected in neurofilament-160(+) and/or microtubule-associated protein-2(+) cells that morphologically resembled n eurons. In addition to bFGF, epidermal growth factor, nerve growth factor, and sonic hedgehog were also capable of generating spherical cell clusters that contained cells that stained for neuronal markers following the additi on of trophic factors. These results suggest that early postnatal dorsal ro ot ganglia contain neural precursors that appear to proliferate in response to various factors and can then be induced to differentiate into neurons. In conclusion, the existence of neural precursors and the possibility of ne urogenesis in postnatal dorsal root ganglia may provide a greater range of plasticity available to somatosensory systems during growth or following in jury, perhaps to replace ineffectual or dying neurons. (C) 2001 Academic Pr ess.