Morimoto K, Sato M
Jpn J Physiol. 1982;32(5):855-71. doi: 10.2170/jjphysiol.32.855.
To examine physiological and pharmacological characteristics of synaptic transmission from taste cells to afferent nerve terminals in frog taste organ, changes in the glossopharyngeal nerve discharges and responses to chemical stimulation of the tongue were examined by intra-arterially perfusing the tongue with Ringer solution containing monoamines and their related substances. Noradrenaline (NA), dopamine (DA), and adrenaline (AD) produced an increase in the spontaneous glossopharyngeal nerve discharges as well as an enhancement of taste responses to various kinds of chemical stimuli, but they did not affect tactile response. NA was the most effective of the three. Monoamine-releasing agents, tyramine and 6OHDA, enhanced spontaneous nerve discharges but depressed taste responses. Antimonoaminergic agents, phentolamine and phenoxybenzamine (alpha-blockers), increased nerve discharges and depressed taste responses, but did not affect tactile response. DCI (beta-blocker), except at high concentrations, affected neither nerve discharges nor taste responses. Pre-treatment of frogs with monoamine-depleting agents, alpha-MPT and 6OHDA, depressed taste responses. Reserpine enhanced the effect of alpha-MPT. The depressed taste responses recovered after perfusion of the tongue with NA. From the results obtained, the possibility of NA being a transmitter at the afferent synapse in the frog taste organ was discussed.
为研究青蛙味觉器官中从味觉细胞到传入神经末梢的突触传递的生理和药理学特性，通过向舌内动脉灌注含单胺及其相关物质的林格液，检测了舌咽神经放电的变化以及对舌化学刺激的反应。去甲肾上腺素（NA）、多巴胺（DA）和肾上腺素（AD）使舌咽神经的自发放电增加，同时增强了对各种化学刺激的味觉反应，但它们不影响触觉反应。NA是三者中最有效的。单胺释放剂酪胺和6-羟基多巴胺增强了自发神经放电，但抑制了味觉反应。抗单胺能药物酚妥拉明和苯氧苄胺（α受体阻滞剂）增加了神经放电并抑制了味觉反应，但不影响触觉反应。除高浓度外，DCI（β受体阻滞剂）对神经放电和味觉反应均无影响。用单胺耗竭剂α-甲基酪氨酸和6-羟基多巴胺预处理青蛙，会抑制味觉反应。利血平增强了α-甲基酪氨酸的作用。用NA灌注舌头后，被抑制的味觉反应恢复。根据所得结果，讨论了NA作为青蛙味觉器官传入突触递质的可能性。
