Development of sympathetic neurons: Neurotransmitter plasticity and differentiation factors

Abstract

This chapter examines the way sympathetic neurons acquire their adult complement of transmitters to determine whether the neurotransmitter phenotype of sympathetic neurons is plastic during development in vivo as in vitro. The neurotransmitter plasticity displayed by sympathetic neurons is not unique. Examination of the development of transmitter properties has disclosed a number of examples of altered expressions of transmitter synthetic enzymes and neuropeptides, and it suggests that not only quantitative but also qualitative changes in transmitter expressions are common. The chapter presents a hypothesis that the local environment, rather than the target, provides the instructive cues that result in the acquisition of the adult transmitter phenotype. Significant progress has been made in identifying the differentiation factors that affect the sympathetic neurotransmitter phenotype. Two of these, leukemia inhibitory factor (LIF) and ciliary neurotrophic factor (CNTF), are members of a recently described family of cytokines, and they have actions on hematopoietic cells and neurons, including sympathetic, sensory, and motor neurons. The present challenge is to define where and how these cytokines and other differentiation factors normally act to influence the properties of not only sympathetic neurons but also other classes of responsive neurons. © 1994, Elsevier Science Publishers, B.V.