Conserved gene expression patterns reveal structural homology between the mammalian and avian hippocampus

Neuropeptide Y (NPY) has been implicated as a neuromodulator mediating a number of physiological functions including anxiety, processing of gustatory information and energy homeostasis. We find that a subset of olfactory sensory neurons (OSNs) in zebrafish express NPY from early development through adulthood. Co-localization studies with OSN type markers suggest that NPY is limited to ciliated OSNs. These NPY-positive OSNs terminate in discrete glomeruli in the olfactory bulb and co-localize with the synaptic vesicle protein SV2. With a view to interrogate the functional role of NPY in olfaction, we have developed an aversive olfactory assay in zebrafish larvae. Larvae treated with a small molecule NPY receptor antagonist fail to respond to aversive olfactory signals. Our data implicates for the first time and a direct function for NPY in olfaction.