DORSAL-ROOT GANGLION NEURONS REQUIRE FUNCTIONAL NEUROTROPHIN RECEPTORS FOR SURVIVAL DURING DEVELOPMENT

Neurotrophins are the most profound known regulators of survival in th e developing peripheral nervous system. Within dorsal root ganglia, th e signalling receptors for the different members of the neurotrophin f amily are distributed in distinct patterns suggesting regulation of di fferent functional classes of sensory neurons. Abnormalities observed in neurotrophin receptor mutant mice have confirmed this idea. Both tr kA (-/-) and trkC (-/-) mice have striking neurological defecits refer rable to subpopulations of DRG neurons which have distinct axon projec tions in the periphery. These results thus generalize concepts of depe ndence on target-derived factors based on extensive work With the prot otypical neurotrophin, nerve growth factor. Further analysis of these animals also provides evidence for more complex developmental mechanis ms including dependence on locally synthesized neurotrophins at early developmental stages and plasticity of neurotrophin receptor expressio n.