A taste receptor required for the caffeine response in vivo

TitleA taste receptor required for the caffeine response in vivo
Publication TypeJournal Article
Year of Publication2006
AuthorsMoon SJ, Köttgen M, Jiao Y, Xu H, Montell C
JournalCurr Biol
Volume16
Pagination1812-7
Date Published2006 Sep 19
ISSN0960-9822
KeywordsAnimals, Caffeine, Chemoreceptor Cells, Drosophila, Drosophila Proteins, Gene Deletion, Neurons, Afferent, Phosphodiesterase Inhibitors, Receptors, G-Protein-Coupled, Theobromine
Abstract

Caffeine is a methylxanthine present in the coffee tree, tea plant, and other naturally occurring sources and is among the most commonly consumed drugs worldwide. Whereas the pharmacological action of caffeine has been studied extensively, relatively little is known concerning the molecular mechanism through which this substance is detected as a bitter compound. Unlike most tastants, which are detected through cell-surface G protein-coupled receptors, it has been proposed that caffeine and related methylxanthines activate taste-receptor cells through inhibition of a cyclic nucleotide phosphodiesterase (PDE) . Here, we show that the gustatory receptor Gr66a is expressed in the dendrites of Drosophila gustatory receptor neurons and is essential for the caffeine response. In a behavioral assay, the aversion to caffeine was specifically disrupted in flies missing Gr66a. Caffeine-induced action potentials were also eliminated, as was the response to theophylline, the methylxanthine in tea. The Gr66a mutant exhibited normal tastant-induced action potentials upon presentation of theobromine, a methylxanthine in cocoa. Given that theobromine and caffeine inhibit PDEs with equal potencies , these data further support the role of Gr66a rather than a PDE in mediating the caffeine response. Gr66a is the first gustatory receptor shown to be essential for caffeine-induced behavior and activity of gustatory receptor cells in vivo.

DOI10.1016/j.cub.2006.07.024
Alternate JournalCurr. Biol.
PubMed ID16979558
Grant ListDC007864 / DC / NIDCD NIH HHS / United States