CHANGES OF NMDA RECEPTOR-BINDING IN SPONTANEOUSLY EPILEPTIC RAT AND PARENT STRAINS

We measured the binding of -[(+/-)2-carboxypiperazin-4-yl]propyl-1-pho sphonic acid ([H-3]CPP), a competitive ligand for N-methyl-D-aspartate (NMDA) receptors, in double mutant spontaneously epileptic rats (SER: zi/zi, tm/tm) and their parent strains, zitter rats and tremor Tats, and WTC rats (control rats from tremor rats derived from Kyoto:Wistar rats) before and after the onset of seizures in tremor rats and SER. S ignificantly lower [H-3]CPP binding receptor density (B(max)) was foun d in the cortex of SER and zitter rats at 12-15 weeks of age than in t hat of WTC rats and tremor rats, and at 4 weeks of age the Bmax in zit ter rats was lower than that in the other strains. The reduction of Bm ax in SER at 12-15 weeks of age may reflect a down regulation of NMDA receptors due to repetitive tonic seizures in SER.