Glutamate Models of Psychosis: from Theory to Treatment
Bita Moghaddam
University of Pittsburgh
Disturbances in glutamate-mediated neurotransmission are implicated in
a range of psychiatric disorders including schizophrenia, substance abuse,
and mood disorders. Glutamatergic involvement in of schizophrenia was initially
based on the ability of N-methyl-D-aspartate receptor antagonists to induce
schizophrenia-like symptoms, as well as emergent literature documenting
disturbances of glutamate-related gene expression and metabolic pathways
in pscyhosis. Our animal models modeling studies have long implicated excess
glutamate in cortical and hippocampal regions in the pathophysiology of
schizophrenia.Although the idea of hyperfunctionality of glutamate synapses
is counterintuitive to some traditional views on glutamate neurotransmission
and schizophrenia (e.g. that glutamate is hypofunctional in schizophrenia),
the mechanism has gained acceptance because it is now consistent with a
number of clinical findings in schizophrenia. At a theoretical level, this
hyperfunctionality may serve as a common pathway for the diverse genetic
causes of the illness and is consistent with inflammatory and neurotoxic
processes including apoptosis that may mediate cortical and hippocampal
atrophy. Based on our findings, reducing glutamate neurotransmission in
schizophrenia through modulatory mechanisms such as agonists of metabotropic
glutamate receptor 2 (mGlu2) has been in the pipeline for more than a decade.
While the approach of reducing glutamate availability may not provide long-term
efficacy for treating psychosis and other symptoms in chronically ill patients,
recent work suggests that it may be a useful approach as a prevention strategy
in individuals at high risk for schizophrenia or during the early stages
of the illness.
Related
papers:
Moghaddam, B. (2013) A mechanistic approach to preventing schizophrenia
in at-risk individuals. Neuron, 78(1): 1-3.
Moghaddam,
B., Javitt, D. (2012) From revolution to evolution: the glutamate hypothesis of
schizophrenia and its implications for treatment. Neuropsychopharmcology
Reviews, 37(1):4-15.
Wood,
J., Kim, Y.B., Moghaddam, B.
(2012) Disruption of prefrontal cortex large scale neuronal activity by
different classes of psychotomimetic drugs. Journal of Neuroscience, 32(9): 3022-31.Link
Jackson, M.E., Homayoun, H., Moghaddam, B. (2004) NMDA receptor hypofunction
produces concomitant firing rate potentiation and burst activity reduction
in the prefrontal cortex. Proceedings of the National Academy of Sciences
(USA), 101:8467-8472. Link