A common brain chemical is enough to keep a fruit fly up at night. Scientists know that the chemical, a neurotransmitter called GABA, is important for the human sleep cycle. But a new study is the first to show the chemical also controls whether a Drosophila melanogaster nods off or tosses and turns all night.
The research, published in the March Nature Neuroscience, shows that a receptor for GABA controls whether fruit flies fall asleep, just as it does in humans. But the receptor, found in cells that control wakefulness, doesn’t influence whether the fruit flies stay asleep or determine how long they slumber, says Leslie Griffith, a neuroscientist at Brandeis University in Waltham, Mass.
Fruit flies with mutations in the GABA receptor, which is encoded by a gene called Rdl, fell asleep faster than normal fruit flies. An epilepsy drug called carbamazepine has the opposite effect, keeping fruit flies awake. A common side effect of carbamazepine is insomnia.
GABA receptors form channels that help generate electric currents in some brain cells, enabling communication between neurons. The mutation in the Rdl GABA receptor causes the channel to stay open, blocking wake signals and giving Mr. Sandman more time to work his magic. Carbamazepine works like a quick-reset button, closing the channel and allowing the cell to fire messages quickly.
The discovery may lead to better drugs for people with certain types of insomnia, Griffith says.