In flies, consuming a high-sugar diet reduces sensitivity to sweetness

In fruit flies fed a high-sugar diet for a week, a complex that regulates taste-related sensory neurons reprogrammed the neurons to make the flies less sensitive to sweet taste. Half of these changes were not reversed even after the flies returned to a control diet, the study shows, suggesting that the flies’ perception of sweet taste was permanently altered. Anoumid Vaziri and colleagues suggest that these lasting changes can influence animals towards eating habits that promote obesity. Their study focused on the epigenetic regulator Polycomb Repressive Complex 2.1 (PRC2.1), which is also found in humans. While previous research has suggested that unhealthy foods with a lot of sugar, salt, and fat distort human perception of taste, prompting us to indulge in them, the molecular mechanisms underlying this phenomenon have been difficult to identify due to the complexity of taste in mammals. To explore these mechanisms in a simpler organism, Vaziri et al. fed with Drosophila melanogaster flies on a sugary diet (30% sucrose) or a control diet (5% sucrose) for 7 days. Next, they compared the flies’ responses to three different concentrations of sweetness based on how far they extended their proboscis – an established proxy for the taste response commonly used by fruit fly researchers – finding that the flies fed the ad high sugar content showed a substantially reduced response to sweet taste compared to the control group. However, flies with mutations in one or more of the protein components of the PRC2.1 complex showed the same response to sweet taste in both diets, further indicating the important role of this epigenetic regulator in attenuating sugar perception. “The mechanisms we discovered are similar to those that lead to depression and anxiety in people who experience trauma,” says Monica Dus, corresponding author of the study. “In this case, eating sugar changes the taste system so that the animal is forced to make unhealthy food choices, always choosing foods that have a higher sugar content. Over time, this blocked behavior will lead to weight gain. obesity and chronic diseases. ”

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