A SINGLE SOCIAL STRESS-EXPERIENCE ALTERS GLUTAMATE RECEPTOR-BINDING IN RAT HIPPOCAMPAL CA3 AREA

The distribution of glutamate receptors in the rat hippocampus was investigated 24 h after the social stress of confrontation with a dominant opponent. AMPA-type glutamate receptors were labeled with the antagonist [H-3]CNQX, and NMDA-type receptors were labeled with the competitive antagonist [H-3]CGP39653. Increased [H-3]CGP39653 labeling was exclusively found in the CA3 stratum radiatum and a decreased [H-3]CNQX labeling was found in several hippocampal areas. Consequently, the ratio NMDA/AMPA binding was significantly increased in CA3 stratum oriens and CA3 stratum radiatum, These results suggest that a single unescapable social stress of defeat alters the impact of the excitatory neurotransmitter glutamate, which is restricted to hippocampal CA3 neurons. Possible consequences of the present findings are discussed.