Abstract: The purpose of this study is to investigate the effect of microinjecti-on of 2-amino-5-phospho-novalerate (APV), N-methyl-D-aspartate(NMD-A) receptor antagonist, to the CA_3 region of the rat hippocampus on thesynaptic efficacy and relative conditioned behavior during establishmentof conditioned drinking response. The results showed that microinjection of APV caused significantlysuppression of the synaptic efficacy and the establishment of conditioneddrinking response. Moreover, the development level of long-term potenti-ation (LTP) is in advance of the development level of correlative condi-tioned behavior. These results indicated that the NMDA receptor is in-volved in the development of learning-dependent LTP.

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