Department of Psychology and Program in Neuroscience, Florida State University, Tallahassee, Florida 32306-4301, USA.
J Neurophysiol. 2012 Nov;108(9):2405-18. doi: 10.1152/jn.00114.2012. Epub 2012 Aug 15.
Sour and salt taste interactions are not well understood in the peripheral gustatory system. Therefore, we investigated the interaction of acetic acid and NaCl on taste processing by rat chorda tympani neurons. We recorded multi-unit responses from the severed chorda tympani nerve (CT) and single-cell responses from intact narrowly tuned and broadly tuned salt-sensitive neurons in the geniculate ganglion simultaneously with stimulus-evoked summated potentials to signal when the stimulus contacted the lingual epithelium. Artificial saliva served as the rinse and solvent for all stimuli [0.3 M NH(4)Cl, 0.5 M sucrose, 0.1 M NaCl, 0.01 M citric acid, 0.02 M quinine hydrochloride (QHCl), 0.1 M KCl, 0.003-0.1 M acetic acid, and 0.003-0.1 M acetic acid mixed with 0.1 M NaCl]. We used benzamil to assess NaCl responses mediated by the epithelial sodium channel (ENaC). The CT nerve responses to acetic acid/NaCl mixtures were less than those predicted by summing the component responses. Single-unit analyses revealed that acetic acid activated acid-generalist neurons exclusively in a concentration-dependent manner: increasing acid concentration increased response frequency and decreased response latency in a parallel fashion. Acetic acid suppressed NaCl responses in ENaC-dependent NaCl-specialist neurons, whereas acetic acid-NaCl mixtures were additive in acid-generalist neurons. These data suggest that acetic acid attenuates sodium responses in ENaC-expressing-taste cells in contact with NaCl-specialist neurons, whereas acetic acid-NaCl mixtures activate distinct receptor/cellular mechanisms on taste cells in contact with acid-generalist neurons. We speculate that NaCl-specialist neurons are in contact with type I cells, whereas acid-generalist neurons are in contact with type III cells in fungiform taste buds.
在周围味觉系统中，酸和盐的味觉相互作用还没有被很好地理解。因此，我们研究了醋酸和 NaCl 对大鼠鼓索神经（CT）味觉细胞的相互作用。我们同时记录了切断的鼓索神经（CT）的多单位反应和从完整的、窄调谐和宽调谐盐敏感神经元中记录的单细胞反应，以及刺激诱发的总和电位，以信号提示刺激接触舌上皮。人工唾液作为所有刺激物的冲洗液和溶剂[0.3 M NH 4 Cl、0.5 M 蔗糖、0.1 M NaCl、0.01 M 柠檬酸、0.02 M 奎宁盐酸盐（QHCl）、0.1 M KCl、0.003-0.1 M 醋酸和 0.003-0.1 M 醋酸与 0.1 M NaCl 混合]。我们使用苯甲脒来评估由上皮钠离子通道（ENaC）介导的 NaCl 反应。CT 神经对醋酸/NaCl 混合物的反应小于各成分反应的总和。单细胞分析显示，醋酸以浓度依赖的方式激活酸通用神经元：增加酸浓度以平行的方式增加反应频率并降低反应潜伏期。醋酸抑制 ENaC 依赖性 NaCl 特异神经元的 NaCl 反应，而醋酸-NaCl 混合物在酸通用神经元中是相加的。这些数据表明，醋酸在接触 NaCl 特异神经元的 ENaC 表达味觉细胞中减弱钠反应，而醋酸-NaCl 混合物在接触酸通用神经元的味觉细胞上激活不同的受体/细胞机制。我们推测 NaCl 特异神经元与 I 型细胞接触，而酸通用神经元与味形味觉的 III 型细胞接触。
