October 21, 2008

Modified Receptor Boosts Dopamine Release

U.S. scientists say they've genetically modified a brain receptor in mice, causing neurons to increase the release of dopamine, making the mice hyperactive.

Researchers led by California Institute of Technology Professor Henry Lester and postdoctoral researcher Ryan Drenan genetically modified a type of brain receptor cell in mice to make it hypersensitive to nicotine.

Receptors of similar types are mostly found on neurons producing the neurotransmitter dopamine, the researchers said. When nicotine binds with those receptor cells, the neurons on which they sit release dopamine.

"We were able to not only isolate this receptor's function, but also to amplify it," said Drenan, "and that allowed us to see exactly what it and it alone is capable of doing in the brain."

They discovered that in mice with the hypersensitive receptors, even low doses of nicotine resulted in a significant release of dopamine, causing the mice to become hyperactive.

The researchers said their findings might be useful in understanding the causes of human hyperactivity such as that observed in attention-deficit hyperactivity disorder.

The study that included scientists from the University of Colorado at Boulder, Rockefeller University, the University of Utah and Targacept, a pharmaceutical company was published in the journal Neuron.