Figure 10. Schematic diagram of the proposed pathway through which IGF-1 induces expression of Brn-4 and neuronal differentiation of hippocampal NSCs.

IGF-1 binds to its receptor in the membrane of NSCs. Then PI3K/Akt are phosphorylated. Subsequently, mTOR, the downstream signal molecule of PI3K/Akt, is activated. As found in this study, mTOR mediated the expression of Brn-4 and neurogenesis function of hippocampal NSCs induced by IGF-1, whereas its downstream effectors are needed to be clarified further.