Neuropeptide Y (NPY) or fragment NPY 13–36, but not NPY 18–36, inhibit retinotectal transfer in cane toads Bufo marinus

Abstract

Previous work suggests that retinotectal information processing is influenced by pretectotectal ipsilateral projections. Neuropeptide Y (NPY) participates in the pretectotectal transmission. The present investigation demonstrates that administration of porcine NPY to the tectal surface causes a profound and prolonged attenuation of the initial excitatory N1 wave of the summated tectal surface field potential (FP) evoked by diffuse light off stimulation. The FP's on response was affected as well, but was less sensitive to NPY. Administration of the fragment NPY 13–36, a Y2 receptor agonist, had a smaller effect than did NPY. Fragment NPY 18–36, however, showed no comparable influences. The data suggest that NPY in the cane toad's pretectotectal pathway controls retinotectal transmission in an inhibitory manner via a Y2 receptor mechanism.