Two geneticists have found that fruit flies respond in the same way to "crack" cocaine as do other animals, including humans. Because humans and fruit flies use many similar biochemical pathways, this discovery suggests that the flies may help scientists unravel the molecular basis of cocaine addiction in people. It may also lay the foundation for highly specific drugs to treat cocaine addiction.
The research, performed by Dr. Jay Hirsh and Colleen McClung of the University of Virginia in Charlottesville, grew out of the group's long-term genetic studies on brain receptors and neurotransmitters--such as dopamine and serotonin--involved in learning, memory, and motor function. Their current findings are featured in a cover story in the January 15 issue of Current Biology.
Cocaine is one of the most powerfully addictive street drugs. Extensive studies on rodents and monkeys have provided little information about the molecular processes that underlie cocaine's behavioral and addictive effects. Using fruit flies in such studies offers several advantages. The genetics of the flies have been intensively studied for 80 years, providing researchers with a rich information base from which to devise and interpret experiments. Not insignificantly, research on flies is cheaper, easier, and faster than similar studies on mammals.
The flies, formally called Drosophila melanogaster, reacted in striking and reproducible ways in response to different levels of cocaine. They also became "sensitized" to the drug, a physiological process thought to be involved in human drug addiction.
"This study shows that the nature of the changes in the Drosophila brain and
nervous system in response to cocaine are probably very similar to those that
occur in the human brain. This gives us a new tool to learn more about brain
receptors and neurotransmitters, and also to better understand the genetic and
Contact: Alisa Zapp Machalek
NIH/National Institute of General Medical Sciences