Reshaping of Sweet Taste Sensation and Feeding by a High Sugar Diet Christina E. May, Anoumid Vaziri, Monica Dus, University of Michigan
Over the past decades our diets have become sweeter because of the use of sugar as a food additive: today over 75% of foods sold at grocery stores contain added sugar (1). During the same time, daily calorie intake increased by 20%. Taste sensation can change with diet (2, 3). For example, high dietary sodium alters the intensity for salt perception and promotes higher sodium intake (4, 5). Similarly, exposure to savory or bitter foods changes taste preference in humans (6), rodents , and invertebrates (7, 8). Whether high dietary sweetness alters sweet taste sensation however, is unknown. Here we asked whether high dietary sugar decreases sweet taste function to promote overconsumption and obesity. To tackle this question, we exploited the relative simplicity of the Drosophila taste system, where the sweet-sensing cells are neurons that project directly to the brain. We show that fruit flies fed a high sugar diet show a dulled sense of sweet taste because of lower responses of the sweet taste neurons to sugar and that this deficit is caused by high dietary sugars, not obesity. By monitoring feeding behavior at high resolution and using opto- and neurogenetics manipulations of sweet taste cell activity, we show the dulling of sweet taste leads to overfeeding and obesity. Preventing a decrease in sweet taste sensation rescues feeding and fat accumulation in animals exposed to the high sugar diet. Our results implicate deficits in sweet taste as drivers of obesity and begin to map the neural underpinnings through which exposure to high dietary sugar reshapes taste function and behavior.
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