Abstract
Purpose::
Neuropeptide Y (NPY), an inhibitory neuropeptide expressed by a moderately dense population of wide-field amacrine and displaced amacrine cells in the rodent retina, acts through multiple (Y1-y6) G-protein-coupled receptors. The purpose of this study was to determine the cellular localization of Y5 receptor in the mouse retina.
Methods::
Polyclonal antisera were raised in rabbit against the mouse Y5 (285-298) receptor and affinity purified using a sepharose affinity column. Y5 immunolabelling was abolished with pre-incubation of the antibody with 10-6M synthetic Y5 (285-298) peptide. Single and double-label immunohistochemistry with antibodies to Y5 and calcium binding protein (CaBP), or Y5 and monoclonal antibody A60 which specifically recognizes the DNA-binding, neuron-specific protein NeuN, were used to characterize Y5 expression in the mouse retina.
Results::
Specific Y5 immunoreactivity was localized to processes in the outer plexiform layer. Immunoreactivity was also prominent in cell processes located throughout the inner plexiform layer and faintly immunoreactive cell bodies in the ganglion cells layer (GCL). Y5 immunoreactivity was observed in fiber bundles in the fiber layer, optic nerve head and optic nerve. Double-label immunohistochemical experiments with CaBP, a horizontal cell marker, confirmed that Y5 immunoreactivity in the outer retina is localized to horizontal cell processes. Double-label immunohistochemical experiments with NeuN, a ganglion cell marker, demonstrated that Y5 immunoreactivity in the GCL was localized to ganglion cells.
Conclusions::
Y5 immunoreactivity in the mouse retina is localized to horizontal cells and ganglion cells indicating that NPY acts on Y5 receptors to modulate multiple neuronal pathways in the mammalian retina.
Keywords: horizontal cells • ganglion cells • neuropeptides