NTF3 and Parkinson disease: In this regard, transplantation of rat neural stem cells endogenously expressing neurotrophin-3 (rNSC-NT3) into Parkinsonian rats treated with 6-hydroxydopamine (6-OHDA) by Gu et al. was shown to improve their spatial learning ability and protect dopamine neurons in the substantia nigra, reversing the main symptoms of PD [113].