Corticosterone decreases 3H-glutamate binding in rat hippocampal formation

The effect of in vivo corticosterone manipulation on binding sites for the excitatory neurotransmitter glutamate was determined using radioligand binding to rat brain cryostat sections and crude synaptic membranes. 3H-glutamate binding to regions of the dorsal hippocampal formation was significantly decreased in adrenalectomized animals following 5-10 days of corticosterone treatment. Corticosterone did not alter 3H-glutamate binding in several other brain regions. The loss in 3H-glutamate binding appeared to be due to a decrease in the maximal number of binding sites, with little change in binding affinity. Both chloride-dependent and chloride-independent 3H-glutamate binding sites were decreased by corticosterone treatment. results indicate that corticosterone can selectively alter binding sites for excitatory amino acids in hippocampal tissue.