Kainic acid-induced limbic seizures cause lasting increases in neurope
ptide Y (NPY) expression in hippocampal granule cells/mossy fibers. Th
e 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 kaini
c acid-induced seizures, Y-1 receptor mRNA levels decreased by 80% in
granule cells and concomitantly increased (by 75%) in CA2 pyramidal ne
urons. Subsequently, persistent decreases in Y-1 mRNA were seen, both
in the stratum granulosum and in CA2. Changes in mRNA concentrations w
ere accompanied by a transient, although non-significant, increase in
[I-125][Pro(34)]PYY binding in the molecular layer of the dentate gyru
s after 4-6 h which was succeeded by a tasting decrease in binding whi
ch indicates a persistent down-regulation of Y-1 receptors in hippocam
pal areas in kainic acid-induced epilepsy. (C) 1997 Elsevier Science I
reland Ltd.