high-salt(HS)diet is strongly associated with increased blood pressure and cardiovascular disease.It is well documented that HS diet is accompanied by changes in cognitive,emotional,and cardiovascular function.Additionally,studies have shown that HS diet increases oxidative stress,which is believed to be associated with change of synaptic plasticity.Hypothesis is that the deficits of learning and memory due to HS diet may be induced by increased oxidative stress.Here,we tested the effect of high salt on anxiety,learning-memory function,oxidative stress and the expression of proteins related to synaptic plasticity in male C57BL/6J mice.Adult mice were fed normal-salt(control; 0.4%NaCl),HS(8%NaCl)diets for 4wk or 7wk(HS-4W; HS-7W).It was found that HS diet for 4wk was sufficient to cause damage to the long-term context memory,and short-term memory impairment occurred in a high salt diet after 7 weeks.Additionally,levels of ROS and H2O2 in the hippocampus were significantly increased,while activities of catalase and superoxide dismutase were decreased in the HS diet mice.On the other hand,the mice from HS-4W and HS-7W group exhibited significant reductions of synapsin I(SYS)and synaptophysin(SYP)in the hippocampus.The low activation of ERK1/ERK2 was founded in the hippocampus after high salt diet,which may also contribute to synaptic plasticity.Taken together,these data demonstrate that HS diets for different time cause variable memory impairment and the change of synaptic plasticity,which may be associated with a redox imbalance in the hippocampus.