McCaughey Stuart A
Department of Anatomy and Cell Biology, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, 19104, United States; Center for Medical Education, Ball State University, Muncie, IN, 47306, United States.
Neurosci Res. 2019 Apr;141:43-51. doi: 10.1016/j.neures.2018.03.006. Epub 2018 Mar 23.
Different gustatory papilla types vary in their locations on the tongue. Distinctions have often made between types, but variation within fungiform papillae has seldom been explored. Here, regional differences in fungiform papillae were investigated by flowing solutions selectively over either an anterior fungiform (AF, tongue tip) or a posterior fungiform (PF, middle third) region as taste-evoked activity was measured in the chorda tympani nerve of C57BL/6J (B6) mice. Significantly larger responses were evoked by NaCl applied to the AF than PF region, and the ENaC blocker amiloride reduced the NaCl response size only for the former. Umami synergy, based on co-presenting MSG and IMP, was larger for the AF than PF region. The regions did not differ in response size to sour chemicals, but responses to l-lysine, l-arginine, sucrose, and tetrasodium pyrophosphate were larger for the AF than PF region. Thus, fungiform papillae on the tongue tip differed from those found further back in their transduction mechanisms for salty and umami compounds. Gustatory sensitivity also showed regional variation, albeit with a complex relationship to palatability and taste quality. Overall, the data support a regional organization for the mouse tongue, with different functional zones for the anterior, middle, and posterior thirds.
不同类型的味觉乳头在舌头上的位置各不相同。人们常常对不同类型的味觉乳头进行区分，但对于菌状乳头内部的差异却鲜有研究。在此，研究人员通过选择性地将溶液流过C57BL/6J（B6）小鼠鼓索神经中测量味觉诱发活动时的前菌状乳头（AF，舌尖）或后菌状乳头（PF，舌前三分之一中部）区域，来研究菌状乳头的区域差异。与PF区域相比，将NaCl应用于AF区域时诱发的反应明显更大，并且ENaC阻滞剂amiloride仅降低了前者对NaCl的反应大小。基于同时呈现味精（MSG）和肌苷酸（IMP）的鲜味协同效应，AF区域比PF区域更大。这两个区域对酸味化学物质的反应大小没有差异，但AF区域对L-赖氨酸、L-精氨酸、蔗糖和焦磷酸四钠的反应比PF区域更大。因此，舌尖上的菌状乳头在对咸味和鲜味化合物的转导机制上与更靠后的菌状乳头不同。味觉敏感性也表现出区域差异，尽管它与适口性和味觉质量之间存在复杂的关系。总体而言，这些数据支持小鼠舌头存在区域组织，其前三分之一、中部和后三分之一具有不同的功能区。
