Towards a glutamate hypothesis of depression: an emerging frontier of neuropsychopharmacology for mood disorders

Neuropharmacology. 2012 Jan;62(1):63-77. doi: 10.1016/j.neuropharm.2011.07.036. Epub 2011 Aug 3.

Abstract

Half a century after the first formulation of the monoamine hypothesis, compelling evidence implies that long-term changes in an array of brain areas and circuits mediating complex cognitive-emotional behaviors represent the biological underpinnings of mood/anxiety disorders. A large number of clinical studies suggest that pathophysiology is associated with dysfunction of the predominant glutamatergic system, malfunction in the mechanisms regulating clearance and metabolism of glutamate, and cytoarchitectural/morphological maladaptive changes in a number of brain areas mediating cognitive-emotional behaviors. Concurrently, a wealth of data from animal models have shown that different types of environmental stress enhance glutamate release/transmission in limbic/cortical areas and exert powerful structural effects, inducing dendritic remodeling, reduction of synapses and possibly volumetric reductions resembling those observed in depressed patients. Because a vast majority of neurons and synapses in these areas and circuits use glutamate as neurotransmitter, it would be limiting to maintain that glutamate is in some way 'involved' in mood/anxiety disorders; rather it should be recognized that the glutamatergic system is a primary mediator of psychiatric pathology and, potentially, also a final common pathway for the therapeutic action of antidepressant agents. A paradigm shift from a monoamine hypothesis of depression to a neuroplasticity hypothesis focused on glutamate may represent a substantial advancement in the working hypothesis that drives research for new drugs and therapies. Importantly, despite the availability of multiple classes of drugs with monoamine-based mechanisms of action, there remains a large percentage of patients who fail to achieve a sustained remission of depressive symptoms. The unmet need for improved pharmacotherapies for treatment-resistant depression means there is a large space for the development of new compounds with novel mechanisms of action such as glutamate transmission and related pathways. This article is part of a Special Issue entitled 'Anxiety and Depression'.

Publication types

  • Review

MeSH terms

  • Animals
  • Antidepressive Agents / pharmacology
  • Antidepressive Agents / therapeutic use
  • Brain / drug effects
  • Brain / metabolism*
  • Drug Evaluation, Preclinical
  • Glucocorticoids / metabolism
  • Glutamic Acid / metabolism*
  • Humans
  • Magnetic Resonance Spectroscopy
  • Mood Disorders / drug therapy
  • Mood Disorders / metabolism*
  • Mood Disorders / pathology
  • Receptors, N-Methyl-D-Aspartate / metabolism
  • Synaptic Transmission / drug effects
  • gamma-Aminobutyric Acid / metabolism

Substances

  • Antidepressive Agents
  • Glucocorticoids
  • Receptors, N-Methyl-D-Aspartate
  • Glutamic Acid
  • gamma-Aminobutyric Acid