The researchers found if they changed the diet of the fruit fly (increasing sugar, removing taste of sugar, increasing protein, changing sugar for complex carbohydrate), this drastically altered how well the fruit fly could taste subsequent sugar after a few days.
“We found that when flies ate unsweetened food, this made sugary food taste much more intense,” Professor Wang said.
“Then we looked at all the proteins that changed in the fruit fly ‘tongue’ in response to diet, and we investigated what was happening,” Professor Neely said.
They found the sensation of taste is controlled by dopamine (the “reward” neuromodulator). The researchers then mapped the pathway and found the same pathways that are well established as controlling learning and memory or promoting long life also enhance taste sensation.
“While this work was conducted in fruit flies, the molecules involved are conserved through to humans. We know humans also experience changes in taste perception in response to diet, so it’s possible the whole process is conserved; we will have to see,” Professor Wang said.
The research published in Cell reports, is a follow up study to Professor’s Neely’s work testing the effects of artificial sweeteners. That research found artificial sweeteners activate a neuronal starvation pathway, and end up promoting increased food intake, especially when combined with a low-carb diet.
“Our first studies were focused on how different food additives impact the brain, and from this we found taste changed in response to diet, so here we followed up that observation and describe how that works,” Professor Neely said. “Turns out the fly ‘tongue’ itself is remembering what has come before, which is kind of neat.”