neuronal plasticity when exposed to chronic unpredictable mild stress（ CUMS） in adulthood. Methods Litters were randomly assigned to four groups： SSM（ stress sensitive group： a daily 3-hour maternal separation + CUMS）， SRM（ stress resilient group： a daily 15-min maternal separation + CUMS）， CUMS（ only CUMS） and NCM（ normal control group）. On Day 4 of parturition， neonatal pups of SRM and SSM group were separated from their mothers for 1 week. Rats were tested in the open field and their immobility time in forced swimming test on PND56（ the 56th day of post natal）. The adult rats of SRM， SSM and CUMS group were exposed to CUMS for 4 weeks. Then the changes of behaviors were reevaluated， at the same time， immunohistochemistry （IHC） were applied to compare the expression of axonal growth and directional differentiation related protein GAP-43（ growth-associated-protein-43）. Results Compared with NCM group， SSM group showed decreased total distance（ F=8.466， P=0.001） and central distance（ F=4.631， P=0.018）， and increased forcing swimming time（ F=5.201， P=0.012）. While there was no statistical significance in the difference between SRM group and NCM group（ P＞ 0.05）. In the adulthood stimulation， CUMS group showed decreased total distance（ P=0.041） and central distance（ P ＜ 0.001） compared to NCM. SSM group showed decreased total distance（ F=8.868， P=0.010） and central distance（ F=13.175，P＜ 0.001） compared to the CUMS group. The expression of GAP-43 downregulated for SSM group and CUMS group compared to NCM group after exposed to CUMS（ F=9.756，P＜0.001）. Comapred SRM group with CUMS group， there was no statistical significance. Conclusions Early long time maternal deprivation leads adult rats more vulnerable to stress and downregulate the expression of GAP-43 suppressing neuronal plasticity.