Given these observations, it can be assumed that NT-3 and NT-4 do not directly affect the occurrence of discogenic pain and the development of IVD degenerative disease of the L/S spine; rather, they exert an indirect effect, acting as activators of several signaling pathways and thereby changing the expression profiles of other neurotrophic factors that are more important in the neo-inversion process. This evidence concerns the gene NTF3 and neurodegenerative disease.