Nerve growth factor enhances dendritic arborization of sympathetic ganglion cells in developing mammals

Recent observations have suggested that the dendritic arbors of sympathetic ganglion cells may be regulated by interactions with their peripheral targets (Voyvodic, 1987a; Yawo, 1987). In order to assess a potential mechanism for such interactions, I have investigated the effects of the target-derived trophic molecule for sympathetic ganglion cells on the development of dendrites in the rat superior cervical ganglion. Systemic treatment of neonatal animals with NGF for 1 or 2 weeks results in a striking expansion of ganglion cell dendritic arbors, as revealed by intracellular staining with HRP. During this period, neurons in treated animals extend new primary dendrites, and the length and branching of existing dendrites are increased compared to age-matched controls. These results support the idea that targets may regulate ganglion cell arbors via elaboration of NGF, and suggest an explanation for the correlation between animal size and dendritic complexity noted in several recent studies (Purves and Lichtman, 1985a; Snider, 1987; Voyvodic, 1987a).