Metyrosine is an inhibitor of tyrosine hydroxylase. In vivo, metyrosine (200 mg/kg) reduces norepinephrine and dopamine levels in rat brain and disrupts conditioned avoidance behavior in a dose-dependent manner. Metyrosine reduces dopamine transporter knockdown-induced hyperactivity and rearing behavior and increases exploratory behavior in a hole board assay in a mouse model of bipolar disorder mania. It reduces hypertension induced by dexamethasone and cyclosporin in rats. Metyrosine also inhibits norepinephrine production and increases plasma levels of leptin in fasted and fed mice.