Effect of inhibitory avoidance training on [H-3]-glutamate binding in the hippocampus and parietal cortex of rats

Glutamate receptors have been implicated in memory formation. The aim of th e present study was to determine the effect of inhibitory avoidance trainin g on specific [H-3]-glutamate binding to membranes obtained from the hippoc ampus or parietal cortex of rats. Adult male Wistar rats were trained (0.5- mA footshock) in a step-down inhibitory avoidance task and were sacrificed 0, 5, 15 or 60 min after training. Hippocampus and parietal cortex were dis sected and membranes were prepared and incubated with 350 nM [H-3]-glutamat e (N = 4-6 per group). Inhibitory avoidance training induced a 29% increase in glutamate binding in hippocampal membranes obtained from rats sacrifice d at 5 min (P<0.01), but not at 0, 15. or 60 min after training, and did no t affect glutamate binding in membranes obtained from the parietal cortex. These results are consistent with previous evidence for the involvement of glutamatergic synaptic modification in the hippocampus in the early steps o f memory formation.