A darting mouse may hold an important clue in the development of Attention Deficit Hyperactivity Disorder (ADHD), autism and bipolar disorder, according to a study by a Vanderbilt University-led research team recently published in the Proceedings of the National Academy of Sciences.
The transgenic mouse, into which was inserted a rare human genetic variation in the dopamine transporter (DAT), could lead to improvements in the diagnosis and treatment of these all-too-common brain disorders, said Randy Blakely, Ph.D., the report's senior author.
The mutation, which has been found in people with ADHD, autism and bipolar disorder, affects the function of DAT, a protein that regulates the brain's supply of the neurotransmitter by removing excess dopamine from the synapse, or the space between nerve cells.
The DAT mutation causes the transporter to become "leaky" and spew out dopamine like "a vacuum cleaner in reverse," said Blakely, Allan D. Bass Professor of Pharmacology.
While mice with leaky DAT proteins have too much dopamine hanging around their synapses, surprisingly they aren't particularly hyperactive, possibly because DAT can still remove some of the dopamine.
But the mice exhibit an unusual "darting behavior." While their wild-type littermates are docile and quite unresponsive when researchers pick them up, those with the mutation "take off."
"Early on," Blakely said, "we could tell which ones carried the mutation by observing this response." Heightened anxiety does not appear to be the cause.
Blakely and his colleagues wonder whether this behavior is a form of "impulsivity." Rather than acting on their memories of being picked up a lot, the mice are opting for an inappropriate escape strategy.
Normal mice also stand up a lot to explore their cage. This "rearing" behavior is exacerbated by stimulant drugs. But not in these mice.
"We wonder whether this may be a sign that their behavior is driven less by searching for clues to appropriate behavior versus acting on innate impulses," Blakely said.
Go here to see the original:
'Darting' mice may hold clues to ADHD, autism, bipolar disorder