Odor-induced cAMP production in Drosophila melanogaster olfactory sensory neurons

Insect odorant receptors are seven transmembrane domain proteins that form cation channels, whose functional properties such as receptor sensitivity are subject to regulation by intracellular signaling cascades. Here, we used the cAMP fluorescent indicator Epac1-camps to investigate the occurrence of odor-induced cAMP production in olfactory sensory neurons (OSNs) of Drosophila melanogaster. We show that stimulation of the receptor complex with an odor mixture or with the synthetic agonist VUAA1 induces a cAMP response. Moreover, we show that while the intracellular Ca2+ concentration influences cAMP production, the OSN-specific receptor OrX is necessary to elicit cAMP responses in Ca2+-free conditions. These results provide direct evidence of a relationship between odorant receptor stimulation and cAMP production in olfactory sensory neurons in the fruit fly antenna and show that this method can be used to further investigate the role that this second messenger plays in insect olfaction.