Geometric Framework for nutrition on Sucrose Taste Sensitization in Drosophila

Numerous studies show dietary carbohydrates (C) affect the sensation of sweetness. However, protein (P) is one of the most critical macronutrients in the diet as well. It is still unclear how carbohydrates and proteins interact to influence sweet taste sensitivity. Here, we use the nutritional geometry framework (NGF) to tackle this problem in Drosophila melanogaster. Our results showed that the combination of high protein and low carbohydrates caused higher taste responses to sucrose stimuli in both sexes. Additionally, transcriptome analysis revealed that the gene expression of glycine, serine, and threonine pathway in the high-protein, low-carbohydrate diet was significantly upregulated, compared to a diet with low protein, and high carbohydrate. We confirmed that serine and threonine supplementation in the high-carbohydrate, low-protein diet enhanced the sucrose sensitivity of flies. Our results demonstrate that sucrose taste sensitivity is affected by the dietary balance of protein and carbohydrates possibly mediated by the change in serine, and threonine. The high protein, low carbohydrate diets enhanced sucrose taste sensitivity. Overall design: Brain mRNA profiles of 4-7-day old flies treated with low protein and high carbohydrates diet(P:C=0:1,360g/L) that caused lower taste responses to sucrose stimuli and high protein and low carbohydrates diet(P:C=1:2,360g/L) that induced higher taste responses to sucrose stimuli.

诸多研究表明，膳食碳水化合物（carbohydrates, C）可影响甜味感知。蛋白质（protein, P）同样是膳食中最为关键的宏量营养素之一，然而目前尚不明确二者如何相互作用，进而调控甜味味觉敏感性。本研究借助营养几何框架（nutritional geometry framework, NGF），以黑腹果蝇（Drosophila melanogaster）为模型开展相关研究。结果显示，高蛋白与低碳水的膳食组合可使雌雄果蝇对蔗糖刺激的味觉响应均显著增强。转录组分析表明，相较于低蛋白高碳水膳食，高蛋白低碳水膳食中甘氨酸、丝氨酸与苏氨酸代谢通路的基因表达水平显著上调。本研究进一步证实，在低蛋白高碳水膳食中添加丝氨酸与苏氨酸，可提升果蝇的蔗糖味觉敏感性。综上，蔗糖味觉敏感性受膳食蛋白质与碳水化合物平衡的调控，其潜在机制可能与丝氨酸和苏氨酸的代谢变化相关，而高蛋白低碳水膳食可增强蔗糖味觉敏感性。整体实验设计：对饲喂两种膳食的4-7日龄果蝇进行脑mRNA转录组分析，其中一组饲喂低蛋白高碳水膳食（P:C=0:1, 360g/L），该膳食会降低果蝇对蔗糖刺激的味觉响应；另一组饲喂高蛋白低碳水膳食（P:C=1:2, 360g/L），该膳食可增强果蝇对蔗糖刺激的味觉响应。