Simon S A, Elliott E J, Erickson R P, Holland V F
Department of Neurobiology, Duke University, Durham, NC 27710.
Brain Res. 1993 Jul 2;615(2):218-28. doi: 10.1016/0006-8993(93)90031-h.
Each chorda tympani (CT) nerve innervates taste cells in fungiform papillae on one side of the anterior two-thirds of mammalian tongues. In this study, three effects of unilateral CT transection were investigated: (1) the persistence of taste cells on the ipsilateral and contralateral sides; (2) the ability of the CT to modulate ion transport across the ipsilateral and contralateral sides of canine lingual lingual epithelia; and (3) the effect on contralateral CT responses. Unilateral transection of dog CT caused the mean number of taste buds/fungiform papilla on the ipsilateral side to decrease from five to zero by 29-30 days after surgery. Taste buds reappeared after 44 days but in reduced numbers (two taste buds/papilla). This reappearance of taste buds after 44 days is consistent with the time predicted for the CT to regenerate and reach the anterior portion of the tongue. The number of taste buds/papilla remained unchanged on the contralateral side. Measurements of the short-circuit current (Isc) across both ipsilateral and contralateral sections of isolated canine lingual epithelia were performed at various times after unilateral CT transection. Both sides responded similarly. The Isc began to decline after 3 days, reached a minimum after approximately 18 days (approximately 40% of control Isc) and increased to control values after approximately 40 days. This includes experiments performed 30 days after surgery, when no taste buds were present on the ipsilateral side and the Isc was 80% of control values. For all times after CT transection, amiloride, an epithelial Na+ channel blocker, inhibited Isc. Thus, epithelial cells in dog tongue have amiloride-inhibitable pathways. These results show that proteins involved in active Na+ transport across lingual epithelial can be modulated by CT nerve fibers.
每一条鼓索神经（CT）支配哺乳动物舌头前三分之二一侧的菌状乳头中的味觉细胞。在本研究中，研究了单侧CT横断的三种效应：（1）同侧和对侧味觉细胞的存留情况；（2）CT调节犬舌上皮同侧和对侧离子转运的能力；（3）对侧CT反应的影响。犬CT单侧横断后，术后29 - 30天同侧味蕾/菌状乳头的平均数量从5个降至0个。44天后味蕾重新出现，但数量减少（每个乳头2个味蕾）。44天后味蕾的重新出现与预测的CT再生并到达舌前部的时间一致。对侧味蕾/乳头的数量保持不变。在单侧CT横断后的不同时间，对分离的犬舌上皮的同侧和对侧部分进行短路电流（Isc）测量。两侧反应相似。Isc在3天后开始下降，约18天后达到最低值（约为对照Isc的40%），约40天后增加到对照值。这包括术后30天进行的实验，此时同侧没有味蕾，Isc为对照值的80%。在CT横断后的所有时间，上皮钠通道阻滞剂氨氯地平均抑制Isc。因此，犬舌中的上皮细胞具有氨氯地平可抑制的途径。这些结果表明，参与舌上皮主动钠转运的蛋白质可被CT神经纤维调节。
