Fig. 3.
Citronellal facilitates activation of TrpA1-positive gustatory neurons by NMM at the suboptimal concentration of 1 mM. (A) Typical examples of extracellular action potential recordings of taste neurons in I-type sensilla. The viability of non-responding neurons in WT and TrpA1ins was examined by exposure to 1 mM berberine that stimulates TrpA1-independent bitter signaling in the same neuron as shown in (C). (B) Bar graphs represent averages of spiking frequencies from in (A). (C) Reintroduction of Drosophila TrpA1 cDNAs differentially restored the neuronal responses to a mixture of 2 mM citronellal and 1 mM NMM. (D) A summary of experiments in (C). (E) Neuronal responses to berberine and caffeine were not enhanced by citronellal, unlike NMM. The number of experiments is presented in grey on each bar (B, D, and E). p < 0.001, ANOVA Tukey test.