NGF and excitatory neurotransmitters regulate survival and morphogenesis of cultured cerebellar Purkinje cells

Abstract

The development of cerebellar Purkinje cells is subject to regulation by multiple epigenetic signals. To define mechanisms by which trophic and presynaptic stimulation may potentially regulate Purkinje cell ontogeny, we studied the effects of NGF and excitatory transmitters on Purkinje cell survival and morphological maturation in dissociated cell culture. Purkinje cells were identified by expression of vitamin D-dependent calcium-binding protein and by their characteristic morphology. NGF receptors were selectively localized to Purkinje cells by both ligand and monoclonal antibody binding, suggesting responsivity to the trophic agent. Simultaneous exposure to depolarizing agents and NGF specifically enhanced Purkinje cell survival in culture. NGF, in combination with either high potassium or veratridine markedly increased survival of Purkinje cells. Furthermore, NGF together with the excitatory neurotransmitters aspartate or glutamate promoted a 2-fold increase in survival. In addition, NGF increased Purkinje cell size and promoted neurite elaboration. These effects required simultaneous exposure to NGF and either aspartate, glutamate, or pharmacologic depolarizing agents. Effects on survival or neurite elaboration were not evoked by exposure to trophic factors or transmitters alone. Our results suggest a novel mechanism for regulation of development, in which trophic factor and afferent stimulation interact to promote survival and morphogenesis of developing Purkinje cells.