Bipolar Disorder (BPD or manic-depressive illness) is one of the most serious of all mental disorders, affecting millions of individuals worldwide.
Affected individuals alternate between states of deep depression and mania. While depression is characterized by persistent and long-term sadness or despair, mania is a mental state characterized by great excitement, flight of ideas, a decreased need for sleep, and, sometimes, uncontrollable behavior, hallucinations, or delusions. BPD likely arises from the complex interaction of multiple genes and environmental factors. Unlike some brain diseases, no single gene has been implicated in BPD.
A major limitation to progress in research and treatment has been the lack of an appropriate animal model for BPD. This work was developed to create such a model based on a genetically engineered defect in the GluR6 gene. The glutamate receptor 6 (GluR6 or GRIK2, one of the kainate receptors) gene resides in a genetic linkage region (6q21) associated with BPD. Kainate receptors respond to the neurotransmitter glutamate, and recent research in mood disorders suggests that the glutamatergic system may play a role in causing mood disorders.