Altered expression of NPY-Y-1 receptors in kainic acid induced epilepsy in rats

Kainic acid-induced limbic seizures cause lasting increases in neuropeptide Y (NPY) expression in hippocampal granule cells/mossy fibers. The expression of NPY-Y-1 receptors in these neurons were investigated, using in situ hybridization for Y-1 mRNA and receptor autoradiography with the Y-1-specific ligand [I-125]Pro(34)]PYY. Six hours after kainic acid-induced seizures, Y-1 receptor mRNA levels decreased by 80% in granule cells and concomitantly increased (by 75%) in CA2 pyramidal neurons. Subsequently, persistent decreases in Y-1 mRNA were seen, both in the stratum granulosum and in CA2. Changes in mRNA concentrations were accompanied by a transient, although non-significant, increase in [I-125][Pro(34)]PYY binding in the molecular layer of the dentate gyrus after 4-6 h which was succeeded by a tasting decrease in binding which indicates a persistent down-regulation of Y-1 receptors in hippocampal areas in kainic acid-induced epilepsy. (C) 1997 Elsevier Science Ireland Ltd.