Targeting Glycogen Synthase Kinase-3 in the CNS: Implications for the Development of New Treatments for Mood Disorders

There exists an immediate need to develop novel medications for the treatment of mood disorders such as bipolar disorder and depression. Initial interest in glycogen synthase kinase-3 (GSK-3) as a target for the treatment of mood disorders arose from the finding that the mood stabilizing drug lithium directly inhibited the enzyme. More recent preclinical evidence implicates the modulation of GSK- 3 in either the direct or downstream mechanism of action of many other mood stabilizer and antidepressant medications currently in use. One of the cellular targets of GSK-3, which may mediate some of the effects of lithium and other drugs, is β-catenin, a transcription factor that is rapidly degraded when GSK-3 is active. Recent rodent behavioral data (both genetic and pharmacological) supports GSK-3 representing a therapeutically relevant target of lithium. This includes antidepressant-like behavior in the forced swim test and antimaniclike response to amphetamine following administration of the GSK-3 inhibitor AR-A014418, a findings that is concomitant with an increase in brain β-catenin. The evidence described in this review suggests that regulating GSK-3 may represent a target for novel medications to treat mood disorders.