In April 2006, RIKEN (理研) (The Institute of Physical and Chemical Research) and Nagoya University (名古屋大学) successfully produced the world’s first model mice for bipolar disorder by genetic engineering.
Bipolar disorder is a mental disorder, affecting possibly one in a hundred people. The pathogenic mechanism, however, has not yet been discovered.
Kato, a member of the research team, proposed that the cause is related to a depletion in Mitochondrial DNA, which produces energy in cells. Pursuing this enquiry, he succeeded in producing the model mice whose mitochondrial DNA is abnormal only in the brain.
A normal mouse is nocturnal, active when it is dark and and dormant when it is light. This model mouse, however, stayed active for some time even in light conditions, and became active before dark. It is recognized that this abnormal behavior in mice is similar to human abnormal behavior in bipolar disorder.
In addition, when given drugs, some mice increased their activity levels, exhibiting bipolar symptoms, while others showed improvement depending on the medication administered.
It was researchers’consensus opinion that there was no established model animal for bipolar disorder until then.
The assumptions regarding Mitochondria DNA’s role in bipolar disorder have been strongly supported in this long-running inquiry. But one of the reasons the development of a curative medicine has been delayed is that there has not been a model animal for bipolar disorder. This first model mouse could contribute to a discovery of the pathogenic mechanism behind bipolar disorder and the development of a medicinal cure.
A patent has been applied for the development of model animals in bipolar disorder research.