Brain Norepinephrine System as a Target for Antidepressant and Mood Stabilizing Medications

There are numerous lines of evidence pointing to norepinephrine being of crucial importance in pathophysiology of anxiety and mood disorders. First, norepinephrine projections innervate the limbic system, suggesting the involvement of norepinephrine in the regulation of emotions and cognition. Second, norepinephrine closely interacts with serotonin and dopamine systems, which also play very important roles in the regulation of mood. Third, it has been shown that various agents which increase norepinephrine availability, such as norepinephrine reuptake inhibitors, are also effective antidepressant drugs. And fourth, the depletion of norepinephrine causes a resurgence of depressive symptoms after successful treatment with noradrenergic antidepressant drugs. These observations suggest that the intensification of norepinephrine transmission can be beneficial in the treatment of affective disorders. However, various psychotropic medications have indirect effect on norepinephrine transmission. This review examines the effects of psychiatric medications on the norepinephrine system and proposes how they might be used to improve treatment outcome.