Taste receptor cells use multiple signaling pathways to detect chemicals in potential food items. These cells are functionally grouped into different types: Type I cells act as support cells and have glial-like properties; Type II cells detect bitter, sweet, and umami taste stimuli; and Type III cells detect sour and salty stimuli. We have identified a new population of taste cells that are broadly tuned to multiple taste stimuli including bitter, sweet, sour, and umami. The goal of this study was to characterize these broadly responsive (BR) taste cells. We used an IP₃R3-KO mouse (does not release calcium (Ca²⁺) from internal stores in Type II cells when stimulated with bitter, sweet, or umami stimuli) to characterize the BR cells without any potentially confounding input from Type II cells. Using live cell Ca²⁺ imaging in isolated taste cells from the IP₃R3-KO mouse, we found that BR cells are a subset of Type III cells that respond to sour stimuli but also use a PLCβ signaling pathway to respond to bitter, sweet, and umami stimuli. Unlike Type II cells, individual BR cells are broadly tuned and respond to multiple stimuli across different taste modalities. Live cell imaging in a PLCβ3-KO mouse confirmed that BR cells use this signaling pathway to respond to bitter, sweet, and umami stimuli. Short term behavioral assays revealed that BR cells make significant contributions to taste driven behaviors and found that loss of either PLCβ3 in BR cells or IP₃R3 in Type II cells caused similar behavioral deficits to bitter, sweet, and umami stimuli. Analysis of c-Fos activity in the nucleus of the solitary tract (NTS) also demonstrated that functional Type II and BR cells are required for normal stimulus induced expression.

味觉受体细胞使用多种信号通路来检测潜在食品中的化学物质。这些细胞在功能上分为不同的类型：I型细胞充当支持细胞并具有神经胶质样特性。II型细胞可检测到苦味，甜味和鲜味刺激。III型细胞可检测到酸味和咸味刺激。我们已经确定了新的味觉细胞群，这些味觉细胞广泛地适应了多种味觉刺激，包括苦味，甜味，酸味和鲜味。这项研究的目的是表征这些广泛反应（BR）味觉细胞。我们使用了IP ₃ R3-KO鼠标（不释放钙（Ca ²⁺）（通过苦味，甜味或鲜味刺激刺激后从II型细胞内部存储）来表征BR细胞，而不会从II型细胞产生任何潜在的混淆输入。在来自IP _3的分离的味觉细胞中使用活细胞Ca ²⁺成像在R3-KO小鼠中，我们发现BR细胞是III型细胞的子集，对酸性刺激有反应，但也使用PLCβ信号通路对苦味，甜味和鲜味刺激做出反应。与II型细胞不同，单个BR细胞经过广泛调节，可对不同口味模式下的多种刺激做出反应。PLCβ3-KO小鼠中的活细胞成像证实，BR细胞使用此信号通路来响应苦味，甜味和鲜味刺激。短期行为分析表明，BR细胞对味觉驱动行为做出了重要贡献，并发现BR细胞中PLCβ3或IP _3的丧失II型细胞中的R3对苦味，甜味和鲜味刺激引起相似的行为缺陷。分析孤立道（NTS）核中的c-Fos活性还表明，正常刺激诱导表达需要功能性II型和BR细胞。