London, May 12 : Researchers at the University of Georgia have discovered a fruit fly avoidance mechanism that could lead to new ways to control pain in humans.
At first, fruit flies are so attracted to food that they eat like horses. Hatching inside over-ripe fruit where they were laid, they feed wildly in the sugar-rich environment until nature sends them an offer they can't refuse.
However, they can't really stay in the rotting fruit where they are laid because not only do they risk drowning in the ripening fluid, they are increasingly exposed to harmful microorganisms that can kill them.
In order to survive, they leave the fruit, wander off and burrow into the earth where they avoid the food
Only then can the larvae grow and hatch into flies that will take wing to lay their own eggs.
Now, researchers have discovered for the first time that the important developmental switch from food attraction to aversion in the fruit fly larva is controlled by a timing mechanism in the brain and its sensory system.
They have shown how this important avoidance mechanism has been recruited into evolutionary processes to promote development and could one day lead to new methods of controlling pain in humans and other animals.
"The findings provide an intriguing glimpse into how an animal modulates its chemosensory properties and behaviours in coordination with development," Nature quoted Ping Shen, an assistant professor in the department of cellular biology at UGA and a member of the Biomedical and Health Sciences Institute, as saying.
"Fruit fly larvae are like tadpoles-they have to migrate from their first habitat to stay alive and flourish. What we found was that a molecular timing switch tells them when to quit eating and burrow into the earth. We also found that the same switch can trigger strong cooperative behaviour in the flies," Shen added.
With the help of cutting-edge imaging techniques developed by co-author Andrew Sornborger of the Faculty of Engineering and the department of mathematics and his colleagues, the researchers have imaged the fruit fly with unprecedented sensitivity.
"Analysis techniques have lagged behind image acquisition technology. This work addresses that gap. With our methods we have been able to image the inner workings of the nervous systems in real time amid massive amounts of data," Sornborger said.
Researchers found that the change from eating to non-eating is controlled by a timing mechanism that switches on a fructose sensor and involves a channel protein called PAIN, known to respond to noxious stimuli such as heat and horseradish.
They that said that while all this may seem extremely specialized since it involves fruit flies, that's far from the case.
The molecules at work in this system have counterparts in mammalian models that have been implicated in many psychological processes and behaviours such as the response to food and alcohol and the suppression of anxiety and pain.
Now, researchers hope that understanding the system in the fly could therefore lead to the development of new pain relievers that might do far less harm to the organism involved while shutting down pain at its most basic level.
The research was published in the journal Nature Neuroscience.