Neuropeptide Y: A Novel Olfactory Modulator in Zebrafish, Danio rerio

Abstract

Neuropeptide Y (NPY) has been implicated as a neuromodulator mediating a variety of physiological functions including anxiety, 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 innervate in discrete glomeruli in the olfactory bulb. These NPY neurons seem to form synaptic terminals in the olfactory glomeruli since they are colocalized with synaptic vesicle protein SV2. With a view to interrogate the functional role of NPY in olfaction, we have developed an aversive olfactory assay using zebrafish larvae. The 78 h old larvae showed distinct aversion following treatment with l-cysteine. However, larvae pre-treated with BIBP-3226, a small molecule that serves as NPY receptor antagonist, failed to respond to l-cysteine treatment. For the first time, our data suggest the involvement of endogenous NPY and Y1 receptors in the process of olfaction in zebrafish.