Astringent Effects of Red Wine Associated with Responses of Aquaporins Found in Human Tongue and Salivary Tissues

Aquaporin (AQP) water channels facilitate fluid transport across cell membranes, are implicated in rodent oral water sensing, and were examined in the human tongue for their modulation by mouthfeel compounds and ensuing effects on perception and saliva tribology. Immunohistochemistry demonstrated abundant AQP1 and AQP2 and moderate AQP5 in human tongue and high AQP5 in salivary gland. Trained human tasting panels evaluated astringency intensities; results correlated with wine tannin measures and inhibition of AQP1 water flux (R2 ≥ 0.9). Wine tannin extract additions of 1 g/L reduced cell swelling −125 ± 20% (SE) (P P P < 0.006). Osmotic swelling assays identified wines, red wine polyphenols, alum sulfate, and tannic acidall archetypal astringentsas inhibitors of AQP1 and to a lesser extent AQP5. Astringent block of AQPs present in tongue and salivary gland suggests a mechanistic role of water flux in drying sensations, beyond the established changes in saliva resulting from tannin and proline-rich-protein interactions. Insights into AQPs as molecular components of mouthfeel could inform fundamental debates on how astringent phenomena arise and increase understanding of nutrient sensing and uptake as found within the digestive tract and throughout the body.水通道蛋白（Aquaporin，AQP）是一类介导流体跨细胞膜转运的通道蛋白，其参与啮齿类动物的口腔水感知过程。本研究针对人类舌组织中的AQP展开探究，分析口感化合物对其功能的调控作用，以及该调控对味觉感知与唾液摩擦学特性的后续影响。免疫组织化学检测结果显示，人类舌组织中大量表达AQP1与AQP2，中等水平表达AQP5；而唾液腺组织中则高表达AQP5。经过专业训练的人类感官品评小组对样品的涩感强度进行了量化评估，所得结果与葡萄酒单宁含量测定值以及AQP1水通道通量抑制率呈显著相关（决定系数R²≥0.9）。添加1 g/L的葡萄酒单宁提取物可使细胞肿胀程度降低125 ± 20%（标准误SE），差异具有统计学意义（P < 0.006）。渗透压肿胀实验证实，葡萄酒、红酒多酚、硫酸铝以及单宁酸——均为典型的涩感诱发剂——可抑制AQP1的通道活性，对AQP5的抑制作用相对较弱。舌组织与唾液腺中表达的AQP可被涩感物质阻断，这一结果表明，水通道通量在口腔干燥感的产生机制中扮演了关键角色，而非仅依赖于此前已证实的、由单宁与富脯氨酸蛋白相互作用所引发的唾液成分改变。本研究揭示了AQP作为口感感知分子组分的重要作用，可为涩感现象的产生机制这一基础科学议题提供新的研究视角，同时也有助于加深我们对消化道乃至全身范围内营养物质感知与摄取过程的理解。