Ghrelin,a 28 amino acid hormone mainly produced in the stomach,has neuroprotective and neurogenesis effects.Even though ghrelin could enhance glioma cells motility in vitro,it still largely unknown whether ghrelin could affect the newborn neurons migration and neurites growth.There In the present study,we investigated the effect of ghrelin on newborn neurons that differentiated from midbrain neural stem cells.NSCs were isolated from the rat embryos brain on embryonic day 14.5.NSCs were treated with 0.1 μM ghrelin for 7 days in vitro.Expressions of β-tubulin Ⅲ,DCX and PSA-NCAM were detected by immunofluorescent staining.Rac1 which regulate migration and neurites growth were detected by western bolts.The diameter of neurosphere and the length of process were measured by Image Pro Plus software.Mito Tracker was used to reflect the mitochondrial localization.The peripheral diameter of neurosphere was longer in ghrelin treatment group(385.85±48.78 μm)than control(290.67±41.74μm)(P<0.05).We also found that the length of process in ghrelin treatment group(440.11±59.25 μm)was longer compared with control(341.16±64.34 μm)(P<0.05).Mitochondria were more dispersedly in process.Ghrelin increased the percentage of DCX-positive and PSA-NCAM-positive cells.The Rac1 protein level was upregulated by ghrelin.Ghrelin could enhance NSCs and newborn neurons migration and promote neurites growth.The underlying mechanism may be referred to Rac1 GTPase.