Stress has been suggested to disturb the 5-hydroxytryptamine system and decrease neurogenesis,which contribute to the development of depression.Few studies have investigated the effect of predator stress,a type of psychological stress,on depression and hippocampal neurogenesis in adult mice;we therefore investigated this in the present study.A total of 35 adult male Kunming mice were allocated to a cat stress group,cat odor stress group,cat stress + fluoxetine group,cat odor stress + fluoxetine group,or a control group (no stress/treatment).After 12 days of cat stress or cat odor stress,behavioral correlates of depression were measured using the open field test,elevated plus maze test,and dark-avoidance test.The concentrations of hippocampal 5-hydroxytryptamine and 5-hydroxyindoleacetic acid were measured using high-performance liquid chromatography-electrochemical detection.Neurogenesis was also analyzed using a bromodeoxyuridine and doublecortin double-immunostaining method.Cat stress and cat odor stress induced depression-like behaviors;this effect was stronger in the cat stress model.Furthermore,compared with the control group,cat stress mice exhibited lower 5-hydroxytryptamine concentrations,higher 5-hydroxyindoleacetic acid concentrations,and significantly fewer bromodeoxyuridine+/doublecortin+-labeled cells in the dentate gyrus,which was indicative of less neurogenesis.Tne changes observed in the cat stress group were not seen in the cat stress + fluoxetine group,which suggests that the effects of predator stress on depression and neurogenesis were reversed by fluoxetine.Taken together,our results indicate that depression-like behaviors induced by predator stress are associated with the inhibition of hippocampal neurogenesis.