Journal of Neuroscience, Vol 11, 428-434, Copyright © 1991 by Society for Neuroscience
Increased AMPA-sensitive quisqualate receptor binding and reduced NMDA receptor binding in epileptic human hippocampus
DA Hosford, BJ Crain, Z Cao, DW Bonhaus, AH Friedman, MM Okazaki, JV Nadler and JO McNamara
Division of Neurology, Duke University Medical Center, Durham, North Carolina 27710.
Based on results from the kindling model of epilepsy, we hypothesized that
enhanced binding of radioligands to the NMDA receptor and decreased binding
to the alpha-amino-3-hydroxy-5-methyl-4- isoxazolepropionate
(AMPA)-sensitive quisqualate (ASQ) receptor would be found within epileptic
hippocampi of humans with complex partial epilepsy (CPE). To test these
hypotheses, we used tissue that was surgically removed from patients with
intractable CPE, and control tissue that was obtained at autopsy. We used
autoradiographic techniques to measure ASQ receptor binding (with 3H-AMPA
as the radioligand) and binding to 2 sites on the NMDA receptor/channel
complex: the agonist recognition site (with 3H-glutamate) and the
phencyclidine (PCP) binding site that resides within the NMDA channel [with
3H-N-(1-[thienyl]cyclohexyl) piperidine (TCP) in the presence of saturating
concentrations of NMDA and glycine]. Measurements of receptor binding were
corrected for pathologic alterations in neuronal density. Contrary to our
expectations, ASQ receptor binding was significantly increased (100%; p
less than 0.02) in the dentate gyrus stratum moleculare in patients with
CPE (n = 8), and it was unchanged in other hippocampal regions. In nearby
sections from the same specimens, binding was significantly decreased to
the agonist recognition site of the NMDA receptor in the stratum oriens of
area CA3 (46%; p less than 0.05) and was also decreased to the PCP site in
the stratum radiatum and stratum oriens of CA3 (44% and 74%, respectively;
p less than 0.05). The increase in ASQ receptor binding may contribute to
hyperexcitability in these epileptic patients.(ABSTRACT TRUNCATED AT 250
WORDS)