Institutes of Nursing and Health, College of Nursing and Health, Henan University, Kaifeng, China.
Henan International Joint Laboratory of Nuclear Protein Regulation, Henan University, Kaifeng, China.
Chem Senses. 2020 May 21;45(4):249-259. doi: 10.1093/chemse/bjaa015.
The chorda tympani (CT) nerve is exceptionally responsive to NaCl. Amiloride, an epithelial Na+ channel (ENaC) blocker, consistently and significantly decreases the NaCl responsiveness of the CT but not the glossopharyngeal (GL) nerve in the rat. Here, we examined whether amiloride would suppress the NaCl responsiveness of the CT when it cross-reinnervated the posterior tongue (PT). Whole-nerve electrophysiological recording was performed to investigate the response properties of the intact (CTsham), regenerated (CTr), and cross-regenerated (CT-PT) CT in male rats to NaCl mixed with and without amiloride and common taste stimuli. The intact (GLsham) and regenerated (GLr) GL were also examined. The CT responses of the CT-PT group did not differ from those of the GLr and GLsham groups, but did differ from those of the CTr and CTsham groups for some stimuli. Importantly, the responsiveness of the cross-regenerated CT to a series of NaCl concentrations was not suppressed by amiloride treatment, which significantly decreased the response to NaCl in the CTr and CTsham groups and had no effect in the GLr and GLsham groups. This suggests that the cross-regenerated CT adopts the taste response properties of the GL as opposed to those of the regenerated CT or intact CT. This work replicates the 5 decade-old findings of Oakley and importantly extends them by providing compelling evidence that the presence of functional ENaCs, essential for sodium taste recognition in regenerated taste receptor cells, depends on the reinnervated lingual region and not on the reinnervating gustatory nerve, at least in the rat.
鼓索神经对 NaCl 异常敏感。阿米洛利是一种上皮钠离子通道 (ENaC) 阻滞剂，它能持续显著降低 CT 对 NaCl 的反应性，但对大鼠的舌咽神经 (GL) 没有影响。在这里，我们研究了当 CT 交叉再支配舌后区 (PT) 时，阿米洛利是否会抑制 CT 的 NaCl 反应性。采用全神经电生理记录方法，研究了正常（CTsham）、再生（CTr）和交叉再生（CT-PT）CT 对含或不含阿米洛利以及常见味觉刺激物的混合 NaCl 的反应特性，同时还研究了正常（GLsham）和再生（GLr）GL。CT-PT 组的 CT 反应与 GLr 和 GLsham 组没有差异，但与 CTr 和 CTsham 组的某些刺激物有差异。重要的是，阿米洛利处理并没有抑制交叉再生 CT 对一系列 NaCl 浓度的反应性，而阿米洛利处理显著降低了 CTr 和 CTsham 组对 NaCl 的反应性，对 GLr 和 GLsham 组没有影响。这表明，交叉再生的 CT 采用了 GL 的味觉反应特性，而不是再生 CT 或正常 CT 的反应特性。这项工作复制了 Oakley 等人 50 年前的发现，并且通过提供有力的证据重要地扩展了这些发现，即功能性 ENaC 的存在对于再生味觉感受器细胞中的钠味觉识别至关重要，而这种存在依赖于再支配的舌区域，而不是再支配的味觉神经，至少在大鼠中是这样。
