Neurotrophin-3 selectively increases cultured Purkinje cell survival

Nerve growth factor (NGF) has been shown to promote the survival of cultured cerebellar Purkinje cells, when tested in conjunction with metabotropic receptor activation. In the present study, we examined the effects of neurotrophin-3 (NT-3) and brain-derived neurotrophic factor (BDNF). Following in vitro exposure to NT-3 for 6 days, survival of the calbindin positive Purkinje cells was increased, relative to vehicle-treated controls. The total number of neurons was not affected. These observations suggest a specific action of NT-3 on the Purkinje cell population. Moreover, autoradiographic analysis revealed high affinity [125I]NT-3 binding sites, consistent with a direct action of this neurotrophin. Simultaneous treatment with a metabotropic receptor agonist did not alter the NT-3-elicited increase in cell number. This suggests that NT-3 regulates Purkinje cell survival by a mechanism distinct from the NGF response. When tested alone, or in the presence of metabotropic agonist, BDNF did not affect Purkinje cell number.