Sunflower seed protein (SFSP) is rich in aromatic amino acids.The purpose of this study was to explore the effect on production of dopamine (DA) and 5-hydroxytryptamine (5-HT) in brain and the antidepressant-like effect of SFSP when it was used as the main protein source of dietary food.C57BL/6J mice were fed with food which soy protein (model control,MOD),sunflower seed protein (SFSP),and whey protein (WPC,positive control) as the main protein source,respectively,for 2 months.The chronic unpredictable mild stress (CUMS) model was established to induce depression in mice.The normal group (CON,10 animals/group) was not exposed to the CUMS model.SFSP significantly prevented the decrease of sucrose preference rate,the increase of immobility time in the tail suspension test and forced swimming test and improved anxiety behavior in the open field test and elevated plus maze test caused by CUMS.The effect was not different from whey protein.SFSP also increased the levels of 5-HT,DA,norepinephrine and brain-derived neurotrophic factor in hippocampus,increased serum tryptophan,phenylalanine,tyrosine concentrations and the ratio of tryptophan over large neutral amino acids.At the same time,it reduced the level of corticosterone in plasma,increased the superoxide dismutase,glutathione peroxidase and catalase activity,and reduced the malondialdehyde and reactive oxygen species levels in cortex of depressed mice.SFSP played a role in preventing depression by increasing the absorption of aromatic amino acids,increasing monoamine neurotransmitters concentrations in hippocampus,and preventing oxidative stress in cortex.