The heterodimeric protein T1R2/T1R3 is a chemoreceptor mediating taste perception of sugars, several amino acids, and non-caloric sweeteners in humans and many other vertebrate species. The T1R2 and T1R3 proteins are expressed not only in the oral cavity, but also in the intestine, pancreas, liver, adipose tissue, and in structures of the central nervous system, which suggests their involvement in functions other than gustatory perception. In this study, we analyzed the role of the T1R3 protein in regulation of glucose metabolism in experiments with the gene-knockout mouse strain C57BL/6J-Tas1r3tm1Rfm (Tas1r3-/-), with a deletion of the Tas1r3 gene encoding T1R3, and the control strain C57BL/6ByJ with the intact gene. Glucose tolerance was measured in euglycemic or food-deprived mice after intraperitoneal or intragastric glucose administration. We have shown that in the Tas1r3-/- strain, in addition to the disappearance of taste preference for sucrose, glucose tolerance is also substantially reduced, and insulin resistance is observed. The effect of the Tas1r3 gene knockout on glucose utilization was more pronounced in the euglycemic state than after food deprivation. The baseline glucose level after food deprivation was lower in the Tas1r3-/- strain than in the control strain, which suggests that T1R3 is involved in regulation of endogenous glucose production. These data suggest that the T1R3-mediated glucoreception interacts with the KATP-dependent mechanisms of regulation of the glucose metabolism, and that the main role is likely played by T1R3 expressed in the pancreas and possibly in the central nervous system, but not in the intestinal mucosa, as it was suggested earlier.

中文翻译：

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T1R3受体蛋白对不同血糖水平小鼠糖代谢调控的参与

异二聚体蛋白 T1R2/T1R3 是一种化学感受器，可介导人类和许多其他脊椎动物物种对糖、几种氨基酸和无热量甜味剂的味觉感知。T1R2 和 T1R3 蛋白不仅在口腔中表达，还在肠、胰腺、肝脏、脂肪组织和中枢神经系统结构中表达，这表明它们参与味觉以外的功能。在本研究中，我们在基因敲除小鼠 C57BL/6J-Tas1r3tm1Rfm (Tas1r3-/-) 实验中分析了 T1R3 蛋白在调节葡萄糖代谢中的作用，缺失了编码 T1R3 的 Tas1r3 基因，以及具有完整基因的对照菌株 C57BL/6ByJ。在腹膜内或胃内施用葡萄糖后，在正常血糖或食物剥夺的小鼠中测量葡萄糖耐量。我们已经表明，在 Tas1r3-/- 菌株中，除了对蔗糖的味觉偏好消失之外，葡萄糖耐量也显着降低，并观察到胰岛素抵抗。Tas1r3 基因敲除对葡萄糖利用的影响在正常血糖状态下比食物剥夺后更明显。Tas1r3-/- 菌株在食物剥夺后的基线葡萄糖水平低于对照菌株，这表明 T1R3 参与了内源性葡萄糖产生的调节。这些数据表明，T1R3 介导的葡萄糖感受与 KATP 依赖的葡萄糖代谢调节机制相互作用，主要作用可能由在胰腺和中枢神经系统中表达的 T1R3 发挥作用，但不在肠道中粘膜，正如之前所建议的那样。