A high-protein diet readily leads to anxiety and depression,and autonomous behaviors are an important avenue to judge anxiety and depression.In this study,we investigated the intervention effect of different doses of L-theanine (100,200 and 400 mg/(kg mb·d)) (intragastric administration for 40 days) on behavioral changes in SD rats (SPF grade,male,6 weeks old) fed five experimental diets with different protein-to-energy (P:E) ratios of 20%,30%,40% and 50% through open field and light/dark box tests and physiological and biochemical characteriz...