Tyrosylleucine (Tyr-Leu, YL) TFA, an orally active dipeptide, exhibits a potent antidepressant-like activity.In Vitro: Tyrosylleucine (Tyr-Leu, YL) increases the amount of cells expressing c-Fos, a marker for neuronal activity, in the dentate gyrus of the hippocampus.In Vivo: Tyrosylleucine (Tyr-Leu, YL) dose-dependently exhibits potent anxiolytic-like activity (0.1-1 mg/kg, i.p.)[2].