Neurotrophin-3 (NT-3) is a neurotrophic factor in the NGF family of neurotrophins. NT-3 has activity on certain neurons of the peripheral and central nervous systems, supporting survival and differentiation of e, Xenopus/Amphibian,isting and new neurons. Neurotrophins function primarily to regulate naturally occurring cell death of neurons during development. Two additional structurally homologous neurotrophic factors have been identified: brain-derived neurotrophic factor (BDNF) and neurotrophic 4 (NT-4), also designated NT-5.