Chapter 5 Developmental changes in the neurotrophic factor survival requirements of peripheral nervous system neurons

Abstract

Publisher Summary This chapter shows that neurons are generated in excess in the developing vertebrate nervous system, and those that are superfluous to requirement are eliminated in a phase of cell death that occurs shortly after they innervate their targets. The proposal that neuronal survival is dependent on and regulated by substances synthesized in limiting amounts by their target fields has been substantiated by work on nerve growth factor (NGF). The tissues innervated by NGF-dependent neurons contain trace quantities of NGF in proportion to their innervation density and these neurons are eliminated in development by function-blocking anti-NGF antibodies or by null mutations in the NGF or NGF receptor tyrosine kinase (trkA) genes. This chapter discusses the neurotrophic factor switching in trigeminal ganglion neurons. Several populations of neural crest-derived sensory neurons change their neurotrophin requirements during the development. The majority of neurons of the jugular ganglion and the neural crest-derived part of the trigeminal ganglion of chicken embryos are supported in culture by BDNF, NT3, and NGF early in their development, and subsequently lose responsiveness to BDNF and NT3, but remain dependent on NGF. This chapter discusses these other populations of sensory neurons and ends with a look at the sympathetic neurons.