Department of Otolaryngology and Rocky Mountain Taste and Smell Center, University of Colorado School of Medicine, Aurora, CO, USA.
Chem Senses. 2020 Oct 9;45(7):533-539. doi: 10.1093/chemse/bjaa044.
Studies have suggested that communication between taste cells shapes the gustatory signal before transmission to the brain. To further explore the possibility of intragemmal signal modulation, we adopted an optogenetic approach to stimulate sour-sensitive (Type III) taste cells using mice expressing Cre recombinase under a specific Type III cell promoter, Pkd2l1 (polycystic kidney disease-2-like 1), crossed with mice expressing Cre-dependent channelrhodopsin (ChR2). The application of blue light onto the tongue allowed for the specific stimulation of Type III cells and circumvented the nonspecific effects of chemical stimulation. To understand whether taste modality information is preprocessed in the taste bud before transmission to the sensory nerves, we recorded chorda tympani nerve activity during light and/or chemical tastant application to the tongue. To assess intragemmal modulation, we compared nerve responses to various tastants with or without concurrent light-induced activation of the Type III cells. Our results show that light significantly decreased taste responses to sweet, bitter, salty, and acidic stimuli. On the contrary, the light response was not consistently affected by sweet or bitter stimuli, suggesting that activation of Type II cells does not affect nerve responses to stimuli that activate Type III cells.
研究表明，味觉细胞之间的通讯在向大脑传递信号之前就已经形成了味觉信号。为了进一步探索细胞内信号调制的可能性，我们采用光遗传学方法，使用在特定的 III 型细胞启动子 Pkd2l1（多囊肾病 2 样 1）下表达 Cre 重组酶的小鼠，与表达 Cre 依赖性通道视紫红质（ChR2）的小鼠杂交，来刺激酸敏感（III 型）味觉细胞。将蓝光应用于舌头上可以特异性地刺激 III 型细胞，避免了化学刺激的非特异性影响。为了了解味觉模式信息是否在向感觉神经传递之前在味蕾中进行预处理，我们在向舌头上应用光和/或化学味觉刺激物的同时记录了鼓索神经的活动。为了评估细胞内调制，我们比较了有或没有同时激活 III 型细胞的情况下，神经对各种味觉刺激物的反应。我们的结果表明，光显著降低了对甜味、苦味、咸味和酸味刺激的味觉反应。相反，光反应不受甜味或苦味刺激的一致影响，这表明 II 型细胞的激活不会影响激活 III 型细胞的刺激物对神经的反应。
