Department of Bio-Science, Faculty of Bio-Science, Nagahama Institute of Bio-Science and Technology.
Biomed Res. 2021;42(2):43-51. doi: 10.2220/biomedres.42.43.
The perception of tastes is sensed by the receptors that stimulate sensory cells. We previously reported that TRPA1 and TRPV1 channels expressed in the oral cavity of mammals, are activated by the auto-oxidized product of epigallocatechin gallate (oxiEGCG), a major astringent catechin in green tea. Here, we investigated and compared the sensitivity of TRPA1 and TRPV1 from various animals to astringent polyphenols. We selected three polyphenols, oxiEGCG, tannic acid and myricetin. HEK293T cells expressing TRPA1 or TRPV1 from mammal, bird, reptile, amphibian, and fish, were analyzed for their activation by the Ca-imaging. We found the apparent diversity in the polyphenol-sensitivity among various animals. Mammalian TRPs showed relatively higher sensitivity to polyphenols, and especially, human TRPA1 and TRPV1 could be activated by all of three polyphenols at 20 μM. Reptile TRP channels, however, were insensitive to any polyphenols examined. Moreover, the polyphenol-sensitivity of zebrafish TRPA1 and TRPV1 was quite different from that of medaka TRP channels. Since many polyphenols are present in plants and the sensing of polyphenols using TRP channels in the oral cavity might cause astringent taste, the observed diversity of the polyphenol-sensitivity of TRP channels might be involved in the divergence in the food habit of various animals.
味觉的感知是由刺激感觉细胞的受体来感知的。我们之前报道过，哺乳动物口腔中表达的 TRPA1 和 TRPV1 通道被表没食子儿茶素没食子酸酯（oxiEGCG）的自氧化产物激活，oxiEGCG 是绿茶中主要的涩味儿茶素。在这里，我们研究并比较了 TRPA1 和 TRPV1 对涩味儿多酚的敏感性。我们选择了三种多酚，oxiEGCG、单宁酸和杨梅素。用 Ca2+成像法分析了表达来自哺乳动物、鸟类、爬行动物、两栖动物和鱼类的 TRPA1 或 TRPV1 的 HEK293T 细胞对它们的激活情况。我们发现不同动物之间多酚敏感性存在明显的多样性。哺乳动物 TRP 对多酚表现出相对较高的敏感性，特别是人源 TRPA1 和 TRPV1 可以被三种多酚在 20 μM 时激活。然而，爬行动物的 TRP 通道对所有测试的多酚都不敏感。此外，斑马鱼 TRPA1 和 TRPV1 的多酚敏感性与 medaka TRP 通道的多酚敏感性有很大不同。由于许多多酚存在于植物中，口腔中使用 TRP 通道来感知多酚可能会产生涩味，因此观察到的 TRP 通道对多酚的敏感性的多样性可能与各种动物的食物习性的差异有关。
