Abstract
Neurotrophin molecules have been shown to play important roles in the survival of neurons during devel opment. Most early studies concentrated on the initially discovered factor—nerve growth factor. Recent work has demonstrated that nerve growth factor belongs to a family of neurotrophins that include brain-derived neurotrophic factor, neurotrophin-3, and neurotrophin-4/5. These neurotrophins exert their action via high- affinity receptors known as trks (trkA, trkB, and trkC). A major goal of present research is to identify the neuronal locus of different trks to permit inferences about the specificity of action of the different growth factors. However, recent evidence suggests complex relationships between neurotrophins and trk receptors. These issues are explored in the context of dorsal root ganglion cells and motor neurons. Functional studies of the effects of nerve growth factor on its target cells, the nociceptive afferents, illustrate that this neurotro phin plays a role in development and function, which goes well beyond its classical role in promoting the survival of neurons during the early phases of development. The Neuroscientist 1:26-34, 1995