Differential dopaminergic modulation of the antennal lobe of Drosophila melanogaster.

Olfaction plays a key role in the ability of organisms to monitor their ever-changing chemical environment. Dopamine is a key modulator of the mammalian and insect nervous systems, including the fruit fly Drosophila melanogaster. While there are few indications for dopamine signaling in the fly's first-order olfactory processing center, the antennal lobe (AL), the role of dopamine in Drosophila early olfactory processing remains unknown. Here we reveal broad dopamine receptor expression in key AL cell types. Dopamine application differentially modulates AL output in an odor-dependent manner. Furthermore, we identify AL-innervating neurons expressing the marker for dopaminergic cells, tyrosine hydroxylase, and show that activation of these neurons leads to dopamine release in the AL. Finally, we find that endogenous dopamine release affects AL output in a similar manner to dopamine application.