CHANGES IN PROTEIN-SYNTHESIS AND SYNTHESIS OF THE SYNAPTIC VESICLE PROTEIN, SYNAPTOPHYSIN, IN ENTORHINAL CORTEX FOLLOWING INDUCTION OF LONG-TERM POTENTIATION IN DENTATE GYRUS - AN AGE-RELATED STUDY IN THE RAT

We have examined protein synthesis in entorhinal cortex following indu ction of long-term potentiation (LTP) in perforant path-granule cell s ynapses. The data presented here indicate that there was an increase i n [S-35]methionine labelling of TCA-precipitated proteins and [S-35]me thionine labelling of synaptophysin in the ipsilateral entorhinal cort ex 40 min after induction of LTP in dentate gyrus. Intraventricular in jection of both the NMDA antagonist, D-amino-phosphonovalerate, and th e protein synthesis inhibitor, anisomycin reduced protein synthesis th ough the decrease caused by anisomycin was much more profound. Both ag ents blocked induction of LTP and the increase in protein synthesis an d synaptophysin synthesis which accompanied LTP. These data indicate a close coupling of increased protein synthesis in the entorhinal corte x and expression of LTP in the dentate gyrus. This coupling was furthe r suggested by the absence of an LTP-associated increase in protein sy nthesis in aged animals, in which LTP was markedly attenuated. The pos sibility that these changes impact on morphological changes which acco mpany LTP is discussed. (C) 1997 Elsevier Science Ltd.