CELLULAR-LOCALIZATION OF NEUROPEPTIDE-Y RECEPTORS IN THE RAT HIPPOCAMPUS - LONG-TERM EFFECTS OF LIMBIC SEIZURES

To clarify the cellular localization of neuropeptide-Y receptor subtyp es in the dentate gyrus and CA3 sector of the rat dorsal hippocampus a nd their changes after kainic acid-induced seizures, we used receptor autoradiography to measure [I-125]PYY binding to Y-1 and Y-2 receptors after colchicine treatment. Fifteen days after colchicine infusion in the dorsal hippocampus granule cells and their messy fibres degenerat ed while the hilar interneurons and CA3 pyramidal cells were spared. T his treatment markedly decreased [I-125]PYY binding to Y-1 receptors i n the molecular layer of the dentate gyrus (-82%) and in the hilus (-7 0%). [I-125]PYY binding to Y-2 receptors was reduced by 40% and 48%, r espectively, in the CA3 region and in the hilus. Thirty days after kai nic acid treatment, [I-125]PYY binding to Y-1 receptors was decreased by 35% in the molecular layer of the dentate gyrus whereas the binding to Y-2 receptors was increased by 116% in the hilus. The effect of co lchicine in kainic acid-treated rats indicates that these plastic chan ges occur selectively on granule cell projections.