Objective To investigate the effects of high-fat feeding during pregnancy and lactation on the behaviors and learning memory in adult male offspring,as well as explore its possible mechanisms.Methods Female SD rats were exposed to either high fat diet (HF) or normal diet (ND) during pregnancy and lactation period.From weaning,all male offspring were fed with ND until 120-day.The offspring whose mothers were fed with HF or ND received 14 d chronic unpredictable mild stress (CUMS) or normal circumstance,and being divided into ND group,ND+CUMS group,HF group and HF+CUMS group(9 rats in each group).The Open-field test,sucrose preference test and forced swimming test were used to evaluate the depressive-like behaviors,and Morris water maze test was employed to assess the learning and memory ability.Moreover,blood samples were taken via chronically implanted cardiac catheters for measurement of adrenocorticotropic hormone (ACTH) and corticosterone (CORT) levels in another set of DN group and HF group with normal circumstance during baseline and restraint stress (1 h).Results (1) Compared with the ND group,the sucrose preference in the HF group were decreased (P＜0.05).Compared with ND group,ND +CUMS group showed more serious depressive-like behavior.Vertical score in open-field test (11.36±8.25) and sucrose preference(0.63±0.04) of HF+CUMS group,were lower than those of the ND+CUMS group ((17.12±7.54),(0.73±0.05),respectively).The immobility time in forced swimming test of HF+CUMS group ((33.16±6.35)s) were longer than that of ND+CUMS group ((25.74±7.31) s).(2) In Morris water maze test,the crossing platform times of the HF group was less than those of the HF group.Compared with ND+CUMS group,the target quadrant time,effective area residence time and crossing platform times of HF+CUMS group were decreased significantly (P＜0.05).(3)There was no differences in basal ACTH and CORT between ND group and HF group (P＞0.05).Both ND group and HF group exhibited significantly elevated levels of plasma ACHT and CORT during restraint,but without significant difference between these two groups (P＞ 0.05).Within 3 h after restraint,the HF group showed significant increase of ACTH and CORT compared with ND group(P＜0.05).Conclusion As one kind of distress in early life,high-fat geeding through pregnancy and lactation increase the susceptibility and severity of depressive-like behaviors in adult offspring,as well as reducing the learning and memory ability,and the activity of hypothalamic-pituitary-adrenal axis activity during stress may contribute to the changes.