Identification of a Single Pair of Interneurons for Bitter Taste Processing in the Drosophila Brain
Identification of a Single Pair of Interneurons for Bitter Taste Processing in the Drosophila Brain
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DOI：
10.1016/j.cub.2018.01.084
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发表时间：
2018-03-19
期刊：
影响因子：
9.2
通讯作者：
VijayRaghavan, K.
中科院分区：
文献类型：
--
作者：
Bohra, Ali Asgar;Kallman, Benjamin R.;VijayRaghavan, K.
果蝇由于其大脑的神经解剖结构相对简单，且具有强大的遗传和转基因技术，已成为研究味觉系统组织和功能的优秀模型系统。因此，在分子和细胞水平上，对味觉信息的外周检测和编码已经有了很大的了解。相比之下，人们对处理这些信息并诱导行为适当运动输出的中枢神经回路知之甚少。在这里，我们通过特定驱动系将功能行为测试与靶向转基因表达结合起来，以鉴定位于大脑食管下带的单个双侧同源的苦味敏感中间神经元对。解剖和功能数据表明，这些中间神经元接受来自苦味敏感味觉受体神经元的特定突触输入。靶向转基因激活和灭活实验表明，这些苦味敏感中间神经元可以在很大程度上抑制对食欲刺激（如糖和水）的喙部伸展反射。这些功能实验，以及钙成像研究和钙调制光激活比率积分器（CaMPARI）标记，表明这些一级局部中间神经元在抑制对苦味的反应中发生的喙延伸反射中起重要作用。综上所述，我们的研究提出了成年果蝇苦味敏感味觉回路中一个关键味觉中间神经元的细胞鉴定和功能表征。
Drosophila has become an excellent model system for investigating the organization and function of the gustatory system due to the relatively simple neuroanatomical organization of its brain and the availability of powerful genetic and transgenic technology. Thus, at the molecular and cellular levels, a great deal of insight into the peripheral detection and coding of gustatory information has already been attained. In contrast, much less is known about the central neural circuits that process this information and induce behaviorally appropriate motor output. Here, we combine functional behavioral tests with targeted transgene expression through specific driver lines to identify a single bilaterally homologous pair of bitter-sensitive interneurons that are located in the subesophageal zone of the brain. Anatomical and functional data indicate that these interneurons receive specific synaptic input from bitter-sensitive gustatory receptor neurons. Targeted transgenic activation and inactivation experiments show that these bitter-sensitive interneurons can largely suppress the proboscis extension reflex to appetitive stimuli, such as sugar and water. These functional experiments, together with calcium-imaging studies and calcium-modulated photoactivatable ratiometric integrator (CaMPARI) labeling, indicate that these first-order local interneurons play an important role in the inhibition of the proboscis extension reflex that occurs in response to bitter tastants. Taken together, our studies present a cellular identification and functional characterization of a key gustatory interneuron in the bitter-sensitive gustatory circuitry of the adult fly.